WO2010050289A1 - Pressure sensor diagnosing method, and common rail type fuel injection control device - Google Patents

Abstract

Disclosed is a pressure sensor diagnosing method for making it possible to diagnose the presence/absence of abnormality with a simple constitution but without providing any dedicated circuit for diagnosing the action of a pressure sensor.  An electronic control unit (4) feeds fuel injection valves (2-1 to 2-n) acting as a piezo-injector with a predetermined drive current (Is) for a predetermined drive time (ET).  In the ringing of the terminal voltage of the piezo-injector which occurs for the feeding period, the potential difference between a first peak voltage which occurs at first after the power feed and a second peak voltage which occurs next is determined.  A standard rail pressure intrinsic to the potential difference is determined on the basis of a predetermined correlation between the potential difference of the first peak voltage and the second peak voltage and the standard rail pressure.  It is determined that the pressure sensor (11) is abnormal, if the difference from a detected rail pressure obtained by a pressure sensor (11) is larger than a predetermined threshold valve.

Description

Pressure sensor diagnosis method and common rail fuel injection control device

The present invention relates to abnormality diagnosis of a sensor operation, and more particularly, to the realization of abnormality diagnosis with a simple configuration without using dedicated parts.

For example, in an electronic control device for an internal combustion engine of an automobile typified by a diesel engine, various sensors are provided, and detection signals thereof are used for operation control of the internal combustion engine.
As one of such sensors, a pressure sensor for detecting a rail pressure in a common rail fuel injection control device is important for realizing appropriate fuel injection, and various measures for detecting a failure have been proposed. .

As one of the failure diagnosis of the pressure sensor in such a common rail fuel injection control device, for example, in order to diagnose the failure of the pressure sensor, a command to intentionally increase the rail pressure and a command to decrease the energization time of the injector are issued. As a result, there has been proposed a method for estimating that there is no failure in the pressure sensor when it is determined that there is no change in the fuel injection amount and no change in the exhaust gas characteristics (for example, Patent Document 1). Etc.).

However, in the above-described failure diagnosis method, in order to detect a failure of the pressure sensor, it is necessary to command an unnecessary rail pressure increase regardless of the original fuel injection, which not only leads to redundant control operations, For some reason, an unnecessary increase in rail pressure may actually occur, which may affect the fuel injection operation.
Japanese Patent Laid-Open No. 10-325352

The present invention has been made in view of the above circumstances, and a pressure sensor capable of diagnosing the presence or absence of an abnormality with a simple configuration without providing a dedicated circuit for diagnosing the operation of the abnormality or failure of the pressure sensor. A diagnostic method and a common rail fuel injection control device are provided.

According to the first aspect of the present invention, the fuel in the fuel tank is pressurized and pumped to the common rail by the high-pressure pump, and the high-pressure fuel is supplied to the internal combustion engine via the fuel injection valve using the piezo injector connected to the common rail. A pressure sensor diagnosis method in a common rail fuel injection control device, wherein the common rail pressure is controllable based on a detection signal of a pressure sensor that detects the pressure of the common rail. ,
Applying a predetermined drive current to the piezo injector for a predetermined drive time, acquiring a change in a predetermined section of the terminal voltage of the piezo injector that occurs during the energization period, and determining the predetermined terminal voltage of the acquired piezo injector A standard rail pressure to be generated with respect to a change in the section is obtained based on a predetermined correlation between the predetermined change in the terminal voltage and the standard rail pressure,
When the difference between the detected rail pressure obtained by the pressure sensor and the standard rail pressure obtained based on the predetermined correlation is greater than a predetermined threshold, the pressure sensor is determined to be abnormal. A pressure sensor diagnostic method is provided.
According to the second aspect of the present invention, the fuel in the fuel tank is pressurized and pumped to the common rail by the high-pressure pump, and the high-pressure fuel is supplied to the internal combustion engine via the fuel injection valve using the piezo injector connected to the common rail. A common rail fuel injection control device configured to be controllable based on a detection signal of a pressure sensor that detects the pressure of the common rail by an electronic control unit.
The electronic control unit is
Applying a predetermined drive current to the piezo injector for a predetermined drive time, acquiring a change in a predetermined section of the terminal voltage of the piezo injector that occurs during the energization period, and determining the predetermined terminal voltage of the acquired piezo injector A standard rail pressure to be generated for a change in the section is calculated based on a predetermined correlation between the predetermined change in the terminal voltage and the standard rail pressure,
It is determined whether the difference between the detected rail pressure obtained by the pressure sensor and the standard rail pressure obtained based on a predetermined correlation is greater than a predetermined threshold, and the detection obtained by the pressure sensor A common rail fuel configured to determine that the pressure sensor is abnormal when it is determined that the difference between the rail pressure and the standard rail pressure obtained based on a predetermined correlation is greater than a predetermined threshold. An injection control device is provided.
According to the third aspect of the present invention, the fuel in the fuel tank is pressurized and pumped to the common rail by the high-pressure pump, and the high-pressure fuel is supplied to the internal combustion engine via the fuel injection valve using the piezo injector connected to the common rail. A pressure sensor diagnosis method in a common rail fuel injection control device, wherein the common rail pressure is controllable based on a detection signal of a pressure sensor that detects the pressure of the common rail. ,
Pressure sensor diagnosis configured to determine whether or not there is an abnormality in the pressure sensor based on a first peak voltage in the pulsation of the terminal voltage generated after the start of energization of the piezo injector and a terminal voltage at the end of energization of the piezo injector. A method is provided.
According to the fourth aspect of the present invention, the fuel in the fuel tank is pressurized and pumped to the common rail by the high-pressure pump, and the high-pressure fuel is supplied to the internal combustion engine via the fuel injection valve using the piezo injector connected to the common rail. A common rail fuel injection control device configured to be controllable based on a detection signal of a pressure sensor that detects the pressure of the common rail by an electronic control unit.
The electronic control unit is
A common rail type configured to determine the presence or absence of abnormality of the pressure sensor based on the first peak voltage in the pulsation of the terminal voltage generated after the start of energization of the piezo injector and the terminal voltage at the end of energization of the piezo injector. A fuel injection control device is provided.
According to the fifth aspect of the present invention, the fuel in the fuel tank is pressurized and pumped to the common rail by the high-pressure pump, and the high-pressure fuel is supplied to the internal combustion engine via the fuel injection valve using the piezo injector connected to the common rail. A pressure sensor diagnosis method in a common rail fuel injection control device, wherein the common rail pressure is controllable based on a detection signal of a pressure sensor that detects the pressure of the common rail. ,
The pressure sensor is configured to determine whether or not the pressure sensor is abnormal based on a terminal voltage of the piezo injector at the end of energization of the piezo injector and a target voltage of the terminal voltage of the piezo injector at the end of energization. A pressure sensor diagnostic method is provided.
According to the sixth aspect of the present invention, the fuel in the fuel tank is pressurized and pumped to the common rail by the high pressure pump, and the high pressure fuel is supplied to the internal combustion engine via the fuel injection valve using the piezo injector connected to the common rail. A common rail fuel injection control device configured to be controllable based on a detection signal of a pressure sensor that detects the pressure of the common rail by an electronic control unit.
The electronic control unit is
Obtaining the terminal voltage of the piezo injector at the end of energization to the piezo injector, and based on the obtained terminal voltage of the piezo injector and the target voltage of the terminal voltage of the piezo injector at the end of energization of the piezo injector Thus, there is provided a common rail fuel injection control device configured to determine whether or not the pressure sensor is abnormal.
According to the seventh aspect of the present invention, the fuel in the fuel tank is pressurized and pumped to the common rail by the high-pressure pump, and the high-pressure fuel is supplied to the internal combustion engine through the fuel injection valve using the piezo injector connected to the common rail. And the pressure of the common rail is configured to be controllable based on a detection signal of a pressure sensor that detects the pressure of the common rail, and the piezo injector has a terminal voltage at the end of energization. Is a pressure sensor diagnostic method configured such that the applied voltage of the piezo injector is corrected and driven to be controlled so as to be a predetermined target voltage,
There is provided a pressure sensor diagnosis method configured to determine whether or not the pressure sensor is abnormal when a correction amount of an applied voltage at the end of energization of the piezo injector exceeds a predetermined amount.
According to the eighth aspect of the present invention, the fuel in the fuel tank is pressurized and pumped to the common rail by the high pressure pump, and the high pressure fuel is supplied to the internal combustion engine via the fuel injection valve using the piezo injector connected to the common rail. The common rail pressure can be controlled by the electronic control unit based on a detection signal of a pressure sensor for detecting the pressure of the common rail, and when the energization of the piezo injector is completed. A common rail fuel injection control device configured to control the drive of the piezo injector by correcting the applied voltage of the piezo injector so that the terminal voltage at is a predetermined target voltage,
The electronic control unit is
It is determined whether the correction amount of the applied voltage at the end of energization of the piezo injector exceeds a predetermined amount, and when it is determined that the correction amount of the applied voltage at the end of energization of the piezo injector exceeds a predetermined amount, A common rail fuel injection control device configured to determine that a pressure sensor is abnormal is provided.
According to the ninth aspect of the present invention, the fuel in the fuel tank is pressurized and pumped to the common rail by the high pressure pump, and the high pressure fuel is supplied to the internal combustion engine via the fuel injection valve using the piezo injector connected to the common rail. A pressure sensor diagnosis method in a common rail fuel injection control device, wherein the common rail pressure is controllable based on a detection signal of a pressure sensor that detects the pressure of the common rail. ,
There is provided a pressure sensor diagnostic method configured to determine whether or not there is an abnormality in the pressure sensor based on a change in the terminal voltage within a predetermined section in the pulsation of the terminal voltage that occurs after the start of energization of the piezo injector.

According to the first and second embodiments and the ninth embodiment of the present invention, the original rail pressure should be obtained based on the correlation between the change in the terminal voltage of the piezo injector and the rail pressure, and the detection of the pressure sensor Since it is now possible to detect whether there is an abnormality in the pressure sensor by comparing it with the pressure, it is possible to detect the abnormality of the pressure sensor with a simple configuration by software without newly providing a dedicated circuit for diagnosing the presence of abnormality. As a result, it is possible to provide a highly reliable common rail fuel injection control device by applying such a diagnostic method.
According to the third to ninth aspects of the present invention, it is possible to detect the presence or absence of abnormality of the pressure sensor based on the correlation between the terminal voltage and the rail pressure at a predetermined timing when the piezo injector is driven. Therefore, it is possible to realize an abnormality detection of the pressure sensor with a simple configuration by software without newly providing a dedicated circuit for diagnosing the presence / absence of an abnormality, and to apply such a diagnosis method Thus, there is an effect that a highly reliable common rail fuel injection control device can be provided.

It is a block diagram which shows the example of 1 structure of the common rail type fuel-injection control apparatus to which the pressure sensor diagnostic method in embodiment of this invention is applied. The subroutine which shows the whole procedure in the 1st structural example of the pressure sensor diagnostic process in the 1st and 9th form of this invention performed by the electronic control unit which comprises the common rail type fuel-injection control apparatus shown by FIG. It is a flowchart. It is a subroutine flowchart which shows the specific process sequence of the diagnostic process performed in the pressure sensor diagnostic process shown by FIG. It is a subroutine flowchart which shows the specific process sequence of the last diagnostic process performed in the pressure sensor diagnostic process shown by FIG. It is a subroutine flowchart which shows the whole procedure of the pressure sensor diagnostic process in the 2nd structural example of the pressure sensor diagnostic process in the 1st and 9th form. It is a schematic diagram which shows typically the example of a time change of the terminal voltage at the time of the drive of the piezo injector for demonstrating the basic principle of the pressure sensor diagnostic process of the 1st and 9th form. It is a subroutine flowchart which shows the whole procedure of the pressure sensor diagnostic process of the 3rd and 5th form and the 9th form. It is a subroutine flowchart which shows the specific process sequence of the diagnostic process performed in the pressure sensor diagnostic process shown by FIG. It is a subroutine flowchart which shows the specific process sequence of the last diagnostic process performed in the pressure sensor diagnostic process shown by FIG. It is a subroutine flowchart which shows the specific process sequence of the pressure sensor diagnostic process of the 7th and 9th form. It is a schematic diagram which shows typically the example of a time change of the terminal voltage at the time of the drive of the piezo injector for demonstrating the basic principle of the pressure sensor diagnostic process of the 3rd and 5th form and the 9th form. It is a schematic diagram which shows typically the example of a time change of the terminal voltage at the time of the drive of the piezo injector for demonstrating the basic principle in the pressure sensor diagnostic process of the 7th and 9th form.

DESCRIPTION OF SYMBOLS 1 ... Common rail 2-1 to 2-n ... Fuel injection valve 3 ... Diesel engine 4 ... Electronic control unit 11 ... Pressure sensor 50 ... High pressure pump apparatus

Hereinafter, embodiments of the present invention will be described with reference to FIGS.
The members and arrangements described below do not limit the present invention and can be variously modified within the scope of the gist of the present invention.
First, a configuration example of an internal combustion engine injection control apparatus to which the pressure sensor diagnosis method according to the first and ninth embodiments of the present invention is applied will be described with reference to FIG.
Specifically, the internal combustion engine injection control device shown in FIG. 1 is particularly configured as a common rail fuel injection control device.

This common rail fuel injection control device includes a high pressure pump device 50 that pumps high pressure fuel, a common rail 1 that stores the high pressure fuel pumped by the high pressure pump device 50, and a high pressure fuel supplied from the common rail 1 as a diesel engine. A plurality of fuel injection valves 2-1 to 2-n (hereinafter referred to as “engine”) for supplying fuel to three cylinders, and an electronic control unit for executing a fuel injection control process, a pressure sensor diagnosis process (to be described later), and the like (FIG. 1) In this example, the main component is “ECU”.
Such a configuration itself is the same as the basic configuration of this type of fuel injection control apparatus that has been well known.

The high-pressure pump device 50 has a known and well-known configuration in which the supply pump 5, the metering valve 6, and the high-pressure pump 7 are configured as main components.
In this configuration, the fuel in the fuel tank 9 is pumped up by the supply pump 5 and supplied to the high-pressure pump 7 through the metering valve 6. As the metering valve 6, an electromagnetic proportional control valve is used, and the amount of energization is controlled by the electronic control unit 4, so that the flow rate of fuel supplied to the high-pressure pump 7, in other words, the discharge of the high-pressure pump 7. The amount is to be adjusted.
A return valve 8 is provided between the output side of the supply pump 5 and the fuel tank 9 so that surplus fuel on the output side of the supply pump 5 can be returned to the fuel tank 9. .
The supply pump 5 may be provided separately from the high-pressure pump device 50 on the upstream side of the high-pressure pump device 50 or may be provided in the fuel tank 9.

The fuel injection valves 2-1 to 2-n are provided for each cylinder of the engine 3, and are supplied with high-pressure fuel from the common rail 1 and perform fuel injection by injection control by the electronic control unit 4. Yes.
In the embodiment of the present invention, the fuel injection valves 2-1 to 2-n are made using piezo injectors. Such a piezo injector (not shown) is not unique to the present invention, and has a conventional configuration. The electronic control unit 4 controls the driving of the piezo injector, and the high pressure applied to the cylinders of the engine 3. It is possible to inject fuel. The piezo injector generally has a configuration in which the injection holes (not shown) of the fuel injection valves 2-1 to 2-n are opened by application of a drive voltage. In the embodiment of the present invention, Is also assumed to have such a configuration.

The drive control of such a piezo injector is generally roughly divided into two forms (control patterns).
That is, in one of the two control patterns, the drive voltage of the fuel injectors 2-1 to 2-n is set for each rail pressure, and the fuel injector 2-1 is driven with the drive voltage corresponding to the rail pressure. ˜2-n is driven. Such a control pattern is referred to as a “drive voltage selection type” for convenience.

The other control pattern is to drive the fuel injection valves 2-1 to 2-n with a predetermined drive voltage regardless of the rail pressure. Here, the predetermined drive voltage is a drive voltage that enables injection at the maximum rail pressure, and a value obtained in advance by a test or the like is set. Such a control pattern is referred to as a “driving voltage fixed type” for convenience.
Which control pattern is to be selected should be determined in consideration of the type of vehicle and the displacement.

The electronic control unit 4 has, for example, a microcomputer (not shown) having a known and well-known configuration, a storage element (not shown) such as a RAM and a ROM, and a fuel injection valve 2- A circuit (not shown) for energizing and driving 1 to 2-n and a circuit (not shown) for energizing and driving the metering valve 6 and the like are configured as main components.
In addition to the detection signal of the pressure sensor 11 that detects the pressure of the common rail 1 being input to the electronic control unit 4, various detection signals such as the engine speed, the accelerator opening, the engine coolant temperature, and the fuel temperature are received from the engine. 3 is input to be used for operation control 3 and fuel injection control.
Further, the electronic control unit 4 is adapted to read the terminal voltage of the piezo injector that is required in the pressure sensor diagnosis processing in the embodiment of the present invention to be described later.

Next, a first configuration example of the pressure sensor diagnosis process in the first embodiment of the present invention executed by the electronic control unit 4 will be described with reference to FIGS. 2 to 5.
This first configuration example is configured such that the drive control of the fuel injection valves 2-1 to 2-n by the electronic control unit 4 is performed in the drive voltage selection type control pattern described above. It is suitable for the case.
First, FIG. 2 shows an overall procedure of pressure sensor diagnosis processing in the first configuration example in a subroutine flowchart, and the contents thereof will be described below with reference to FIG.

The pressure sensor diagnosis process in the embodiment of the present invention is executed variously for the vehicle operation control in the electronic control unit 4 and is subjected to a subroutine process as one of the control processes.
When the pressure sensor diagnosis process by the electronic control unit 4 is started, first, whether or not the operation state of the vehicle is suitable for performing pressure sensor diagnosis, that is, whether or not the operating state of the engine 3 is stable. In addition, a determination process for determining whether or not the vehicle is in an overrun state is performed (see steps S102 to S112 in FIG. 2).

Hereinafter, the details of each process will be described. First, the electronic control unit 4 acquires the engine coolant temperature change ΔTc (see step S102 in FIG. 2). That is, based on the engine cooling water temperature input to the electronic control unit 4, the amount of change in the engine cooling water temperature in a predetermined unit time (for example, every minute) is calculated and calculated.
Next, it is determined whether or not the water temperature change amount ΔTc acquired by the calculation is smaller than the predetermined water temperature change amount K1 (see step S104 in FIG. 2). If it is determined that the water temperature change amount ΔTc is smaller than the predetermined water temperature change amount K1 (YES) In the case), the process by the electronic control unit 4 proceeds to the process of step S106 described below. On the other hand, in step S104, the electronic control unit 4 causes the engine coolant temperature change amount not to be smaller than the predetermined water temperature change amount K1, in other words, the engine coolant water temperature change amount exceeds the predetermined water temperature change amount K1. Is determined (in the case of NO), a series of processes are terminated, assuming that the operation state of the vehicle is not suitable for performing pressure sensor diagnosis, and the process returns to a main routine (not shown).
Note that K1 does not need to be limited to a specific value because various appropriate values differ depending on the scale of the vehicle and the like. However, in the embodiment of the present invention, for example, K1 = 5 ° C. is set. .

Next, in step S106, the fuel temperature change amount ΔTf is acquired by the electronic control unit 4. That is, based on the fuel temperature input to the electronic control unit 4, the fuel temperature change amount (fuel temperature change amount) ΔTf in a predetermined unit time (for example, one minute interval) is calculated and calculated.
Next, it is determined whether or not the fuel temperature change amount ΔTf acquired by calculation is smaller than the predetermined fuel temperature change amount K2 (see step S108 in FIG. 2), and it is determined that the fuel temperature change amount ΔTf is smaller than the predetermined fuel temperature change amount K2. In the case of (YES), the process by the electronic control unit 4 proceeds to the process of step S110 described below.

On the other hand, in step S108, the electronic control unit 4 determines that the fuel temperature change amount ΔTf is not smaller than the predetermined fuel temperature change amount K2, in other words, the fuel temperature change amount exceeds the predetermined fuel temperature change amount K2. In the case of NO (in the case of NO), the series of processing is terminated assuming that the operation state of the vehicle is not suitable for performing pressure sensor diagnosis, and the process returns to the main routine (not shown).
Note that K2 does not need to be limited to a specific value because various appropriate values differ depending on the scale of the vehicle and the like. However, in the embodiment of the present invention, for example, K2 = 5 ° C. is set. .
As described above, in the embodiment of the present invention, it is determined whether or not the operating state of the engine 3 is in a stable state based on the change amount of the engine cooling water temperature and the change amount of the fuel temperature. .

Next, in step S110, the accelerator opening detection signal is read into the electronic control unit 4, and then the accelerator opening Acc is 0%, that is, whether the accelerator (not shown) is not depressed. Is determined (see step S112 in FIG. 2).
And in step S112, when it is determined by the electronic control unit 4 that the accelerator opening degree Acc is 0% (in the case of YES), it is determined that the vehicle is in an overrun state, and the processing of the electronic control unit 4 is as follows. Proceeding to step S200, a diagnostic process described below is executed, and thereafter, the process once returns to a main routine (not shown).

As described above, the reason why the overrun state is determined before the diagnosis process is substantially performed is as follows.
In the pressure sensor diagnosis process in the first configuration example, as described above, the drive control pattern of the fuel injection valves 2-1 to 2-n by the electronic control unit 4 is a drive voltage selection type. In the case of this drive voltage selection type, the vehicle operating state is an overrun state, that is, in a state where the accelerator (not shown) is not stepped on, in other words, in a state where the accelerator opening is zero, This is because it is considered that performing the diagnosis process minimizes the influence on the vehicle operation and does not give the driver a sense of incongruity. As will be described in detail later, since the energization current to the fuel injection valves 2-1 to 2-n in the diagnosis process is set to be relatively high, depending on the operating state of the vehicle, the fuel injection valve by the diagnosis process This is because injection due to energization of 2-1 to 2-n may cause a large fluctuation in the engine speed, and may cause discomfort to the driver and passengers.

FIG. 3 shows a specific processing procedure of the diagnostic processing in a subroutine flowchart. Hereinafter, the specific processing procedure will be described with reference to FIG.
First, the series of processing shown in FIG. 3 is executed for each of the fuel injection valves 2-1 to 2-n. That is, the series of processing shown in FIG. 3 is executed for each fuel injection valve 2-1 to 2-n in a predetermined order. This is because, in the pressure sensor diagnosis according to the embodiment of the present invention, as will be described in detail later, the result of the diagnosis processing in each of the fuel injection valves 2-1 to 2-n is comprehensively determined, and finally This is because it is determined whether or not the pressure sensor 11 is abnormal.

Thus, when the electronic control unit 4 starts the diagnostic process, a predetermined drive current is supplied to any one of the fuel injection valves 2-1 to 2-n in a predetermined order. The energization drive at Is is started, and energization is continued for a predetermined energization time ET determined in advance (see step S202 in FIG. 3).
Here, with reference to FIG. 6, the basic principle of the diagnostic processing by energizing the predetermined drive current Is in the embodiment of the present invention will be described.
FIG. 6 shows an example of the time change of the terminal voltage when the fuel injection valves 2-1 to 2-n are energized and driven. The horizontal axis represents the elapsed time from the start of energization, the vertical axis represents the voltage, Represents each.

In FIG. 6, a characteristic line represented by a two-dot chain line shows an example of a voltage change in a normal driving state of the fuel injection valves 2-1 to 2-n.
On the other hand, a characteristic line represented by a solid line indicates a voltage change when the fuel injection valves 2-1 to 2-n are driven by the drive current Is.
As a result of intensive research on the relationship between the operation of the piezo injector and the rail pressure, the inventor of the present application has driven the piezo injector with a high drive current higher than a certain value, and the change in the terminal voltage of the piezo injector It came to the conclusion that the same tendency was shown with respect to rail pressure even if the size of the rail was different.

In addition, the inventor of the present application, in the so-called pulsation in which the terminal voltage of the piezo injector changes up and down after the start of energization, the first peak value (the voltage value at the time t1 in FIG. 6) and the first peak value (hereinafter referred to as the peak value) The difference from the second peak value (voltage value at the time t2 in FIG. 6) when the voltage starts to decrease after the voltage decrease after “first peak value”) is a constant correlation with the rail pressure. It led to the conclusion that there is a relationship, and specifically, it is roughly proportional.
Furthermore, not only the correlation between the potential difference between the first peak value and the second peak value as described above and the rail pressure, but also, for example, the potential difference with respect to the first peak value (the first peak value and the second peak value). It came to the conclusion that a similar correlation is established between the absolute value of the ratio of the difference from the peak value and the rail pressure.
The pressure sensor diagnosis in the embodiment of the present invention is based on such knowledge obtained by the inventor of the present application. Generally speaking, a predetermined drive current is supplied to the piezo injector for a predetermined drive time, A change in a predetermined interval of the terminal voltage of the piezo injector that occurs during the period is acquired, and a standard rail pressure to be generated with respect to the change in the predetermined interval of the terminal voltage of the piezo injector is determined by a predetermined piezo injector The detected rail pressure obtained by the pressure sensor 11 based on a predetermined correlation between the change in the terminal voltage in the predetermined section and the standard rail pressure, and the standard rail pressure obtained based on the previous predetermined correlation It can be said that the presence or absence of abnormality of the pressure sensor 11 is diagnosed based on the difference between the two.

Here, returning to the description of FIG. 3, as described above, after driving of one of the fuel injection valves 2-1 to 2-n by energization of the predetermined drive current Is is started, the piezo injector is turned on. The first peak voltage (first peak voltage) V1 of the terminal voltage is detected by the electronic control unit 4, and the value is provisionally read into a predetermined storage area (not shown) in the electronic control unit 4. (See step S204 in FIG. 3).
Here, the first peak voltage V1 is the voltage at the time t1 in the solid characteristic line of the voltage change illustrated in FIG.

Next, the second peak voltage V2 is read in the same manner (see step S206 in 3). That is, the terminal voltage of the piezo injector once decreases after reaching the first peak voltage V1 (see FIG. 6), decreases to some extent, then starts increasing again, and the first peak voltage It becomes a peak at a voltage V2 lower than V1 (see the location at time t2 in FIG. 6), and shows a change that begins to fall again. If the piezo injector is normal, these changes usually appear within a predetermined energization time ET. The predetermined energization time ET is preferably set to an appropriate value based on the test and simulation results together with the predetermined drive current Is.
In step S206, the second peak voltage is detected by the electronic control unit 4 and temporarily stored in a predetermined storage area (not shown) in the electronic control unit 4.

Next, the process of the electronic control unit 4 proceeds to the process of step S208, and the potential difference ΔV between the first peak voltage V1 and the second peak voltage V2 is calculated and calculated.
Next, potential difference / rail pressure conversion processing is performed based on the potential difference calculated as described above (see step S210 in FIG. 3).
In this potential difference / rail pressure conversion process, as described above with reference to FIG. 6, in the driving of the piezo injector by the predetermined drive current Is, the potential difference ΔV between the first peak voltage V1 and the second peak voltage is: This is based on the correlation with the rail pressure at that time.

Specifically, the correlation between the potential difference ΔV and the rail pressure is obtained in advance, and this is mapped, for example, stored in a predetermined storage area (not shown) of the electronic control unit 4, and obtained in step S208. It is preferable that the original rail pressure (standard rail pressure) Pv to be obtained at that time is obtained with respect to the potential difference ΔV. It is preferable that the rail pressure Pv with respect to a certain potential difference ΔV can be obtained by converting the correlation into an arithmetic expression instead of mapping and using the arithmetic expression.

Next, the sensor detection pressure Pac is acquired by the electronic control unit 4 (see step S212 in FIG. 3). That is, the detection signal of the pressure sensor 11 is input to the electronic control unit 4, but the electronic control unit 4 is predetermined based on the input detection signal of the pressure sensor 11. A rail pressure (detected rail pressure) Pac corresponding to the detection signal is determined by an arithmetic expression or a map.

Next, the absolute value L of the difference between the rail pressure Pv obtained by the voltage difference / rail pressure conversion by the electronic control unit 4 and the detected rail pressure Pac based on the detection signal of the pressure sensor 11 is L = | Pv−Pac. Is calculated as | (see S214 in FIG. 3). Hereinafter, L is referred to as “absolute pressure difference” for convenience of explanation.
Then, it is determined by the electronic control unit 4 whether or not the absolute pressure difference L obtained as described above exceeds a predetermined threshold (see step S216 in FIG. 3), and does not exceed the predetermined threshold. When the determination is made (in the case of NO), the pressure sensor 11 is normal and the series of processes is terminated, and the process in the electronic control unit 4 once returns to the main routine (not shown).

On the other hand, when the electronic control unit 4 determines in step S216 that the absolute pressure difference L exceeds the predetermined threshold (in the case of YES), the pressure sensor 11 is abnormal (sensor abnormality). (See step S218 in FIG. 3), the series of processing is terminated, and the processing in the electronic control unit 4 once returns to the main routine (not shown).
Here, the determination that the sensor is abnormal in step S218 is a result of executing the above-described series of diagnostic processing on one of the fuel injection valves 2-1 to 2-n. When it is determined that there is a sensor abnormality in the diagnosis process for multiple fuel injection valves, as will be described later, from the point of view of careful diagnosis, rather than just performing a response process such as abnormality notification immediately by determining that there is an abnormality. In addition, it is preferable to perform processing such as abnormality notification.

In the above processing example, the correlation between the difference ΔV between the first peak voltage V1 and the second peak voltage V2 and the standard rail pressure Pv is expressed as the standard rail pressure to be generated for a certain potential difference ΔV. Although it is used for obtaining, it is also preferable to be described as follows.
That is, as described above, the ratio of the difference ΔV between the first peak voltage V1 and the second peak voltage V2 to the first peak voltage V1, that is, ΔV / V1 and the rail pressure (standard rail pressure) A correlation is also established between the two.
Therefore, every time ΔV / V1 is acquired based on the correlation between ΔV / V1 and the rail pressure (standard rail pressure), the standard rail pressure with respect to ΔV / V1 is obtained (in step S210 of FIG. 3). Correspondingly, the pressure sensor 11 can be diagnosed by performing the same processing from step S214 onward in FIG.

Next, the final diagnosis process will be described with reference to the subroutine flowchart shown in FIG.
In the embodiment of the present invention, as described above, the series of processes shown in FIG. 3 is performed for each of the fuel injection valves 2-1 to 2 -n, in other words, for the engine 3. Even if it is determined that there is a sensor abnormality by the diagnostic processing in that one fuel injection valve, the corresponding processing such as abnormality notification is not immediately performed. As described below, whether or not abnormality notification is necessary is selected in the final diagnosis process.

Hereinafter, the final diagnosis process will be specifically described.
When the processing is started by the electronic control unit 4, first, the previous fuel injectors 2-1 to 2-n stored in a predetermined storage area (not shown) of the electronic control unit 4 are stored. The results J1 to Jn of the diagnosis process shown in FIG. 3 are read (see steps S216 and S218 in FIG. 3 and step S302 in FIG. 4).
Next, among the diagnosis results read out as described above, the number that the diagnosis result is a sensor abnormality (see step S218 in FIG. 3) is counted by the electronic control unit 4, and the count value of the abnormality diagnosis number N is determined (see step S304 in FIG. 4).

Then, the electronic control unit 4 determines whether or not the count value N is greater than the predetermined reference count value Ns (see step S306 in FIG. 4), and the count value N is not greater than the predetermined reference count value Ns. Is determined (NO), the pressure sensor 11 is not abnormal and a series of processes are terminated, and the process returns to a main routine (not shown).
On the other hand, when the electronic control unit 4 determines in step S306 that the count value N is greater than the predetermined reference count value Ns (in the case of YES), the electronic control unit determines that the pressure sensor 11 is abnormal. 4 is notified of abnormality (see step S308 in FIG. 4).
In addition, although it is suitable for abnormality notification to generate | occur | produce an alarm, an abnormality display, etc. suitably, of course, it does not need to be limited to these and should be selected arbitrarily arbitrarily.

Next, a second configuration example will be described with reference to FIG.
The second configuration example is configured such that the drive control of the fuel injection valves 2-1 to 2-n by the electronic control unit 4 is performed by the above-described drive voltage fixed control pattern. It is suitable for the case.
FIG. 5 is a subroutine flowchart showing the overall procedure of the pressure sensor diagnosis process in the second configuration example. First, the overall procedure of the pressure sensor diagnosis process in the first configuration example is shown. The only difference from the subroutine flowchart of FIG. 2 is that the processing of steps S110 and S112 in FIG. 2 is omitted. In FIG. 5, steps having the same processing contents as those in FIG. 2 are denoted by the same step numbers, and detailed description thereof is omitted.

That is, in the second configuration example, when the drive control of the fuel injection valves 2-1 to 2-n by the electronic control unit 4 is performed with a fixed drive voltage control pattern, the engine coolant temperature When the water temperature change amount ΔTc and the fuel temperature change amount ΔTf of the fuel temperature are determined to be smaller than the predetermined values (see steps S102 to S108 in FIG. 5), the diagnostic processing by the electronic control unit 4 (FIG. 5). Step S200) is executed.
Note that the specific contents of the diagnosis processing are as described above with reference to FIGS. 3 and 4, and therefore detailed description thereof is omitted here.

It should be noted that due to aging deterioration of the piezo injector, the change in the terminal voltage becomes such a state that the pressure sensor 11 is determined to be abnormal by the above-described pressure sensor diagnosis process even though the pressure sensor 11 is normal. There is.
As a countermeasure against such a case, as described below, a process of diagnosing the presence or absence of aging deterioration of the piezo injector is executed, and a misdiagnosis that makes the pressure sensor 11 caused by aging deterioration of the piezo injector abnormal is performed. It is also preferable to avoid the occurrence.

That is, first, every time the piezo injector is energized, the electronic control unit 4 acquires the above-described potential difference ΔV between the first peak voltage and the second peak voltage, and the storage element ( (When not shown), when a new potential difference ΔV is acquired, it is compared with the latest ΔV stored in the storage element, and the difference is a predetermined threshold value. If it is A or less, the pressure sensor diagnosis process (see step S200 in FIG. 2) is executed on the assumption that even if there is an aging of the piezo injector, it does not affect the diagnosis result of the pressure sensor diagnosis process.

On the other hand, if the difference between the new potential difference ΔV and the latest ΔV exceeds a predetermined threshold B greater than the predetermined threshold A (predetermined threshold A <predetermined threshold B), pressure sensor diagnosis processing (see step S200 in FIG. 2) is performed. Therefore, the execution of the pressure sensor diagnosis process is postponed.
Here, by setting the predetermined threshold A to a relatively small value (small value) and setting the predetermined threshold B to a relatively large value, it is possible to detect the possibility of aging deterioration of the piezo injector. is there. This is because, due to the aging of the piezo injector, the voltage deviation corresponding to the above-mentioned minute value is gradually accumulated on the terminal voltage of the piezo injector, in other words, the state equivalent to the integration of the minute value deviation. This is because it is considered that the terminal voltage change state suitable for diagnosing the presence or absence of abnormality of the pressure sensor 11 will eventually disappear.

The above-described diagnosis process for the presence or absence of aging deterioration of the piezo injector is performed when YES is determined in step S112 in FIG. 2 or when YES is determined in step S108 in FIG. Although it is conceivable that the process is performed immediately before the execution of the process of S200, the present invention is not limited to this. For example, the process is performed before the process of step S102 of FIG. 2 or FIG. If it is determined that it does not affect the diagnosis result of the pressure sensor diagnosis process, the process after step S102 may be executed.

Next, third to ninth embodiments of the present invention will be described with reference to FIGS. 1 and 7 to 12.
The members and arrangements described below do not limit the present invention and can be variously modified within the scope of the gist of the present invention.
First, the pressure sensor diagnosis method according to the embodiment of the present invention is suitable for being applied to an internal combustion engine injection control apparatus having the configuration described above with reference to FIG.
Here, the configuration of the internal combustion engine injection control apparatus shown in FIG. 1 will be described again.

Specifically, the internal combustion engine injection control device shown in FIG. 1 is particularly configured as a common rail fuel injection control device.
This common rail fuel injection control device includes a high pressure pump device 50 that pumps high pressure fuel, a common rail 1 that stores the high pressure fuel pumped by the high pressure pump device 50, and a high pressure fuel supplied from the common rail 1 as a diesel engine. A plurality of fuel injection valves 2-1 to 2-n (hereinafter referred to as “engine”) for supplying fuel to three cylinders, and an electronic control unit for executing a fuel injection control process, a pressure sensor diagnosis process (to be described later), and the like (FIG. 1) In this example, the main component is “ECU”.
Such a configuration itself is the same as the basic configuration of this type of fuel injection control apparatus that has been well known.

The high-pressure pump device 50 has a known and well-known configuration in which the supply pump 5, the metering valve 6, and the high-pressure pump 7 are configured as main components.
In this configuration, the fuel in the fuel tank 9 is pumped up by the supply pump 5 and supplied to the high-pressure pump 7 through the metering valve 6. As the metering valve 6, an electromagnetic proportional control valve is used, and the amount of energization is controlled by the electronic control unit 4, so that the flow rate of fuel supplied to the high-pressure pump 7, in other words, the discharge of the high-pressure pump 7. The amount is to be adjusted.
A return valve 8 is provided between the output side of the supply pump 5 and the fuel tank 9 so that surplus fuel on the output side of the supply pump 5 can be returned to the fuel tank 9. .
The supply pump 5 may be provided separately from the high-pressure pump device 50 on the upstream side of the high-pressure pump device 50 or may be provided in the fuel tank 9.

The fuel injection valves 2-1 to 2-n are provided for each cylinder of the engine 3, and are supplied with high-pressure fuel from the common rail 1 and perform fuel injection by injection control by the electronic control unit 4. Yes.
In the embodiment of the present invention, the fuel injection valves 2-1 to 2-n are made using piezo injectors. Such a piezo injector (not shown) is not unique to the present invention, and has a conventional configuration. The electronic control unit 4 controls the driving of the piezo injector, and the high pressure applied to the cylinders of the engine 3. It is possible to inject fuel. The piezo injector generally has a configuration in which the injection holes (not shown) of the fuel injection valves 2-1 to 2-n are opened by application of a drive voltage. In the embodiment of the present invention, Is also assumed to have such a configuration.

The drive control of such a piezo injector is generally roughly divided into two forms (control patterns).
That is, in one of the two control patterns, the drive voltage of the fuel injectors 2-1 to 2-n is set for each rail pressure, and the fuel injector 2-1 is driven with the drive voltage corresponding to the rail pressure. ˜2-n is driven. Such a control pattern is referred to as a “drive voltage selection type” for convenience.

The other control pattern is to drive the fuel injection valves 2-1 to 2-n with a predetermined drive voltage regardless of the rail pressure. Here, the predetermined drive voltage is a drive voltage that enables injection at the maximum rail pressure, and a value obtained in advance by a test or the like is set. Such a control pattern is referred to as a “driving voltage fixed type” for convenience.
Which control pattern is to be selected should be determined in consideration of the type of vehicle and the displacement.

The electronic control unit 4 has, for example, a microcomputer (not shown) having a known and well-known configuration, a storage element (not shown) such as a RAM and a ROM, and a fuel injection valve 2- A circuit (not shown) for energizing and driving 1 to 2-n and a circuit (not shown) for energizing and driving the metering valve 6 and the like are configured as main components.
In addition to the detection signal of the pressure sensor 11 that detects the pressure of the common rail 1 being input to the electronic control unit 4, various detection signals such as the engine speed, the accelerator opening, the engine coolant temperature, and the fuel temperature are received from the engine. 3 is input to be used for operation control 3 and fuel injection control.
Further, the electronic control unit 4 is adapted to read the terminal voltage of the piezo injector that is required in the pressure sensor diagnosis processing in the embodiment of the present invention to be described later.

Next, pressure sensor diagnosis processing in the third, fifth, and ninth embodiments of the present invention that is executed by the electronic control unit 4 will be described with reference to FIGS. 7 to 9 and FIG.
First, FIG. 7 shows an overall procedure of pressure sensor diagnosis processing in the first configuration example in a subroutine flowchart, and the contents thereof will be described below with reference to FIG.

The pressure sensor diagnosis process in the embodiment of the present invention is executed variously for the vehicle operation control in the electronic control unit 4 and is subjected to a subroutine process as one of the control processes.
When the pressure sensor diagnosis process by the electronic control unit 4 is started, first, whether or not the operation state of the vehicle is an operation state suitable for performing the pressure sensor diagnosis, that is, the operation state of the engine 3 is stabilized. Is determined (see steps S502 to S512 in FIG. 7).

Hereinafter, the details of each process will be described. First, the electronic control unit 4 obtains the engine coolant temperature change ΔTc (see step S502 in FIG. 7). That is, based on the engine cooling water temperature input to the electronic control unit 4, the amount of change in the engine cooling water temperature in a predetermined unit time (for example, every minute) is calculated and calculated.
Next, it is determined whether or not the water temperature change amount ΔTc acquired by calculation is smaller than the predetermined water temperature change amount K1 (see step S504 in FIG. 7). If it is determined that the water temperature change amount ΔTc is smaller than the predetermined water temperature change amount K1 (YES) In the case), the process by the electronic control unit 4 proceeds to the process of step S506 described below.

On the other hand, at step S504, the electronic control unit 4 causes the engine coolant temperature change amount not to be smaller than the predetermined water temperature change amount K1, in other words, the engine coolant water temperature change amount exceeds the predetermined water temperature change amount K1. Is determined (in the case of NO), a series of processes are terminated, assuming that the operation state of the vehicle is not suitable for performing pressure sensor diagnosis, and the process returns to a main routine (not shown).
Note that K1 does not need to be limited to a specific value because various appropriate values differ depending on the scale of the vehicle and the like. However, in the embodiment of the present invention, for example, K1 = 5 ° C. is set. .

Next, in step S506, the fuel temperature change amount ΔTf is acquired by the electronic control unit 4. That is, based on the fuel temperature input to the electronic control unit 4, the fuel temperature change amount (fuel temperature change amount) ΔTf in a predetermined unit time (for example, one minute interval) is calculated and calculated.
Next, it is determined whether or not the calculated fuel temperature change amount ΔTf is smaller than the predetermined fuel temperature change amount K2 (see step S508 in FIG. 7). If it is determined that the calculated fuel temperature change amount ΔTf is smaller than the predetermined fuel temperature change amount K2 (YES) In the case of (1), the processing by the electronic control unit 4 proceeds to the processing of step S510 described below.

On the other hand, in step S508, the electronic control unit 4 determines that the fuel temperature change amount ΔTf is not smaller than the predetermined fuel temperature change amount K2, in other words, the fuel temperature change amount exceeds the predetermined fuel temperature change amount K2. In the case of NO (in the case of NO), the series of processing is terminated assuming that the operation state of the vehicle is not suitable for performing pressure sensor diagnosis, and the process returns to the main routine (not shown).

Note that K2 does not need to be limited to a specific value because various appropriate values differ depending on the scale of the vehicle and the like. However, in the embodiment of the present invention, for example, K2 = 5 ° C. is set. .
Thus, in the embodiment of the present invention, it is determined whether or not the operating state of the engine 3 is in a stable state based on the amount of change in the engine coolant temperature and the amount of change in the fuel temperature. ing.

Next, in step S510, an elapsed time (energization time) t from the start of energization drive to the piezo injector is acquired, and then whether or not the energization time t exceeds a predetermined energization time Ts is determined. (See step S512 in FIG. 7). The energization time, which is the elapsed time from the start of energization drive, is acquired by a known and known time measuring program executed inside the electronic control unit 4.

Here, the predetermined energization time Ts is determined from the viewpoint of securing a sufficient energization time for obtaining a desired terminal voltage (described later in detail) of a piezo injector in a diagnosis process (step S600 in FIG. 7) described later. An appropriate value should be set for each apparatus based on tests, simulations, and the like. In the embodiment of the present invention, Ts is set to about 300 μs.
In step S512, when it is determined that the energization time t is not longer than the predetermined energization time Ts (in the case of NO), the series of processes is terminated, assuming that the current state is not suitable for performing the diagnostic process. Then, the process returns to the main routine (not shown).
On the other hand, in step S512, when it is determined that the energization time t is longer than the predetermined energization time Ts (in the case of YES), the electronic control unit 4 performs the process as being in a state suitable for the diagnosis process. The process proceeds to step S600, where the diagnosis process described below is executed, and thereafter, the process once returns to the main routine (not shown).

FIG. 8 shows a specific processing procedure of the diagnostic processing in a subroutine flowchart. Hereinafter, the specific processing procedure will be described with reference to FIG.
First, the series of processing shown in FIG. 8 is executed for each of the fuel injection valves 2-1 to 2-n. That is, the series of processing shown in FIG. 8 is executed for each fuel injection valve 2-1 to 2-n in a predetermined order. This is because, in the pressure sensor diagnosis according to the embodiment of the present invention, as will be described in detail later, the result of the diagnosis processing in each of the fuel injection valves 2-1 to 2-n is comprehensively determined, and finally This is because it is determined whether or not the pressure sensor 11 is abnormal.

When the diagnostic process is started by the electronic control unit 4, the value of the first peak value V1 (first actually measured voltage) generated after the energization driving of the piezo injector is started is read by the electronic control unit 4 (FIG. 8). (See step S602).
Here, the basic principle of the diagnostic processing in the embodiment of the present invention will be described with reference to FIG.
First, as a result of earnest research on the relationship between the operation of the piezo injector and the rail pressure, the inventor of the present application has caused an abnormality in the output signal due to a failure of the pressure sensor 11 or the like. When a different incorrect rail pressure is recognized and the piezo injector is driven, there is a certain regularity in the change of the terminal voltage of the piezo injector, and by using this, the failure or abnormality of the pressure sensor 11 is diagnosed I came to the conclusion that I can do it.

FIG. 11 shows an example of the time change of the terminal voltage when the piezo injector is energized. The horizontal axis represents the elapsed time from the start of energization, and the ordinate represents the terminal voltage of the piezo injector. .
The characteristic line represented by a solid line in the figure shows an example of the time change of the terminal voltage during energization driving of the piezo injector at a certain rail pressure when the pressure sensor 11 is normal and the entire vehicle operation is also normal. Is.
In other words, the terminal voltage of a piezo injector generally shows a so-called pulsation state that changes up and down after the start of energization. Immediately after the start of energization, the terminal voltage rises at a relatively fast rate of change and reaches a first peak at a certain voltage (Fig. 11 (voltage value at time t1) at 11 and immediately after that, the voltage starts decreasing and decreases with a time change substantially the same as the rising.
The initial peak voltage immediately after the start of energization is referred to as “charging start peak voltage” for convenience.

When the voltage drops to a certain voltage, the voltage starts to rise again, and reaches a second peak at a certain voltage lower than the first peak voltage described above. Thereafter, the voltage is repeatedly moved up and down in the same manner. At time t2, energization is terminated and the piezo injector is discharged, so that the terminal voltage rapidly decreases (see FIG. 11). The terminal voltage of the piezo injector at time t2 is referred to as “discharge start voltage” for convenience.
In practice, the drive control of the piezo injector is such that the voltage reaches a peak at a preset voltage at the above-described time t1, and the voltage at the time t2 when the energization ends is a voltage set in advance as a target. The size of the energizing current of the piezo injector, the energizing time, etc. are set and driven.
Therefore, when the entire vehicle apparatus is in a normal operation state, the voltage V1 at time t1 and the voltage V2 at time t2 are voltages set in advance or voltages within a predetermined deviation range.

On the other hand, when the rail pressure detected by the pressure sensor 11 differs from the actual rail pressure for some reason, the change in the terminal voltage of the piezo injector is the difference between the actual rail pressure and the detected rail pressure by the pressure sensor 11. It changes as described below depending on the magnitude relationship.
That is, first, when the rail pressure detected by the pressure sensor 11 is lower than the actual rail pressure, the change in the terminal voltage of the piezo injector is, for example, as shown by a characteristic line represented by a one-dot chain line in FIG. The voltage V1 at the time t1 is shifted to a voltage higher than that at the normal time, and the shift amount corresponds to the difference from the original rail pressure, while the voltage V2 at the time t2 is the normal time (in FIG. 11). (See the characteristic line for solid lines).

Further, when the rail pressure detected by the pressure sensor 11 is higher than the actual rail pressure, the change in the terminal voltage of the piezo injector is, for example, like a characteristic line represented by a two-dot chain line in FIG. The voltage V1 at the time t1 is substantially the same value as that at the normal time, while the voltage V2 at the time t2 is shifted to a voltage higher than that at the normal time (see the solid characteristic line in FIG. 11). Corresponds to the difference from the original rail pressure.

From these facts, when the difference between the actual voltage V2 at time t2 and the preset target voltage V2T is larger than the predetermined threshold value α, the rail pressure detected by the pressure sensor 11 is greater than the actual rail pressure. It can be determined that the state is abnormal.
Further, when the difference between the actual voltage V1 at time t1 and the actual voltage V2 at time t2 is larger than the predetermined threshold value β, the rail pressure detected by the pressure sensor 11 is abnormally lower than the actual rail pressure. It can be judged that it is in a state.

Here, returning to the description of FIG. 8, the first measured voltage V1 read in step S602 is the voltage at the time t1 described in FIG.
Next, the time t2 described in FIG. 11, that is, in other words, the voltage (second measured voltage) V2 at the end of energization of the piezo injector is read by the electronic control unit 4 and is stored in the electronic control unit 4. It is temporarily stored in a predetermined storage area (not shown) (see step S604 in FIG. 8).

Next, the target second voltage V2T at time t2 (see FIG. 11) stored in advance in a predetermined storage area (not shown) in the electronic control unit 4 is read (see step S606 in FIG. 8).
The target second voltage V2T is determined in advance as described above with reference to FIG. 11, and is stored in a predetermined storage area (not shown) of the electronic control unit 4.

Next, the electronic control unit 4 determines whether or not the difference between the second actually measured voltage and the target second voltage, V2−V2T exceeds a predetermined threshold α (see step S608 in FIG. 8).
If the electronic control unit 4 determines that V2−V2T> α (YES), it is determined that the pressure sensor 11 is abnormal (see step S612 in FIG. 8), and a main routine (not shown) It will return to once.

On the other hand, if it is determined in step S608 that V2−V2T> α is not satisfied (in the case of NO), the difference between the first actual measurement voltage V1 and the second actual measurement voltage V2 acquired previously is a predetermined threshold value β Is determined by the electronic control unit 4 (see step S610 in FIG. 8).
If it is determined that V1-V2> β is satisfied (in the case of YES), it is determined that the pressure sensor 11 is abnormal (see step S612 in FIG. 8), and the process once returns to the main routine (not shown). .

Here, the determination of the sensor abnormality in step S612 is a result of executing the above-described series of diagnostic processing for one of the fuel injection valves 2-1 to 2-n. When it is determined that there is a sensor abnormality in the diagnosis process for multiple fuel injection valves, as will be described later, from the point of view of careful diagnosis, rather than just performing a response process such as abnormality notification immediately by determining that there is an abnormality. In addition, it is preferable to perform processing such as abnormality notification.

Next, the final diagnosis process will be described with reference to the subroutine flowchart shown in FIG.
In the embodiment of the present invention, as described above, the series of processing shown in FIG. 8 is performed for each of the fuel injection valves 2-1 to 2-n, in other words, for each cylinder of the engine 3. Even if it is determined that the sensor is abnormal due to the diagnosis process in the one fuel injection valve, the corresponding process such as abnormality notification is not performed immediately, but as described below. The necessity of abnormality notification is selected by the final diagnosis process.

Hereinafter, the final diagnosis process will be specifically described.
When the processing is started by the electronic control unit 4, first, the previous fuel injectors 2-1 to 2-n stored in a predetermined storage area (not shown) of the electronic control unit 4 are stored. The results J1 to Jn of the diagnosis process shown in FIG. 8 are read (see step S612 in FIG. 8 and step S802 in FIG. 9).
Next, among the diagnostic results read out as described above, the number of diagnosed sensor abnormalities (see step S612 in FIG. 8) is counted by the electronic control unit 4, and the count value of the number of abnormal diagnoses. N is determined (see step S804 in FIG. 9).

Then, it is determined by the electronic control unit 4 whether or not the count value N is greater than the predetermined reference count value Ns (see step S806 in FIG. 9), and the count value N is not greater than the predetermined reference count value Ns. Is determined (NO), the pressure sensor 11 is not abnormal and a series of processes are terminated, and the process returns to a main routine (not shown).
On the other hand, if the electronic control unit 4 determines in step S806 that the count value N is greater than the predetermined reference count value Ns (in the case of YES), it is determined that the pressure sensor 11 is abnormal and the electronic control unit 4 will be notified of abnormality (see step S808 in FIG. 9).
In addition, although it is suitable for abnormality notification to generate | occur | produce an alarm, an abnormality display, etc. suitably, of course, it does not need to be limited to these and should be selected arbitrarily arbitrarily.

Next, seventh and ninth embodiments of the present invention will be described with reference to FIGS.
First, the basic concept of pressure sensor diagnosis processing in the seventh and ninth embodiments of the present invention will be described with reference to FIG.
FIG. 12 shows an example of changes in the terminal voltage when the piezo injector is energized, as in FIG. 11, in which the horizontal axis indicates the elapsed time from the start of energization and the vertical axis indicates the piezo injector voltage. Yes.
In the figure, a solid characteristic line is an example of a change in the terminal voltage of the piezo injector at a certain rail pressure when the pressure sensor 11 is normal and the entire vehicle apparatus is in a normal operating state.
On the other hand, a characteristic line indicated by a two-dot chain line indicates that a terminal pressure of the piezo injector is obtained when the pressure sensor 11 outputs a rail pressure higher than the original rail pressure due to an abnormality in the output of the pressure sensor 11 or the like. An example in which the voltage change is displaced in the direction in which the voltage increases with respect to the original change, that is, the characteristic line of the solid line is shown.
Note that the times t1 and t2 in FIG. 12 are the same as the times t1 and t2 described above with reference to FIG.

By the way, in general, as indicated by the two-dot chain line in FIG. 12, the change in the terminal voltage of the piezo injector shifts from the solid characteristic line indicating the original change. For example, not only abnormality or failure of the pressure sensor 11 but also sufficient variation due to characteristic variations can occur.
That is, because the detected rail pressure differs from the original rail pressure due to variations in the characteristics of the pressure sensor 11, the drive voltage to the piezo injector indicated by the electronic control unit 4 deviates from the original value. It may be like the characteristic line of the dotted line. The two-dot chain characteristic line in FIG. 12 is an example of a change in the terminal voltage of the piezo injector when the rail pressure detected by the pressure sensor 11 is higher than the original correct rail pressure.

From the viewpoint of correcting the change in the driving voltage of the piezo injector due to the variation in the characteristics of the pressure sensor 11 as described above, the driving control of the piezo injector is conventionally performed by correcting the applied voltage of the piezo injector at the time t2 when the energization ends. Has been done.
That is, first, in the drive control of the piezo injector, as described above with reference to FIG. 11, the target second voltage V2T, which is the target voltage at time t2 (see FIG. 11), is determined according to the rail pressure. It has been. When the difference between the actual terminal voltage of the piezo injector detected at time t2 at a certain injection timing and the target second voltage VT is calculated by the electronic control unit 4 as the correction amount U2, the next injection timing is calculated. In FIG. 4, voltage application (voltage correction) taking this correction amount U2 into account is performed on the piezo injector.

That is, when the terminal voltage of the piezo injector at time t2 is higher than the target second voltage VT, an applied voltage that is lower than the previous applied voltage by the correction amount U2 is applied to the piezo injector at the next driving of the piezo injector. (See FIG. 12).
Considering variations in the output characteristics of the pressure sensor 11, variations in the characteristics of the piezo injector, and the like, the terminal voltage of the piezo injector may deviate from the target second voltage VT to some extent, but the correction amount U2 When the size greatly deviates from the range considered to be affected by variations in the characteristics of the pressure sensor 11 and the piezo injector, it can be considered that the pressure sensor 11 is abnormal or faulty.
In the seventh embodiment, paying attention to this point, the pressure sensor 11 is diagnosed based on the magnitude of the correction amount U2.

Next, the specific contents of the pressure sensor diagnosis processing in the seventh and ninth embodiments will be described with reference to FIG.
First, it is premised that voltage correction is performed in the energization control of the piezo injector by the electronic control unit 4 as described above.
Thus, when the processing is started by the electronic control unit 4, first, a predetermined number of correction amounts U2 are stored (see step S702 in FIG. 10).
Here, the correction amount U2 is as described above with reference to FIG.

When the correction amount U2 is stored a predetermined number of times, the average value (hereinafter referred to as “average correction amount U2av”) is calculated by the electronic control unit 4 (see step S704 in FIG. 10).
The absolute value K of the difference between the average correction amount U2av obtained as described above and the latest correction amount U2 at this time is calculated by the electronic control unit 4 (see step S706 in FIG. 8).

Next, whether or not the absolute value K exceeds the predetermined threshold value Ks is determined by the electronic control unit 4 (see step S708 in FIG. 10), and when it is determined that the absolute value K does not exceed the predetermined threshold value Ks (in the case of NO). Will temporarily return to the main routine (not shown), assuming that there is no abnormality in the pressure sensor 11.
On the other hand, when it is determined in step S708 that the absolute value K exceeds the predetermined threshold Ks (in the case of YES), it is determined that the pressure sensor 11 is abnormal (sensor abnormality) (see step S710 in FIG. 10). ), The series of processes is terminated, and the process in the electronic control unit 4 once returns to the main routine (not shown).

Here, since the determination of sensor abnormality in step S710 is a result of executing the above-described series of diagnostic processing on one of the fuel injectors 2-1 to 2-n, this one sensor From the point of view of careful diagnosis, rather than immediately performing a response process such as abnormality notification only by determining that there is an abnormality, as described above with reference to FIG. 9, in the diagnosis process for a plurality of fuel injection valves When it is determined that the sensor is abnormal, it is preferable to perform processing such as abnormality notification. A detailed description of the final diagnosis process shown in FIG. 9 will not be repeated here.

Since the change in the terminal voltage of the piezo injector is used for the failure diagnosis of the pressure sensor, it can be applied to the diagnosis of the pressure sensor in the common rail fuel injection device using the piezo injector.

Claims (25)

The fuel in the fuel tank is pressurized and pumped to the common rail by a high-pressure pump, and high-pressure fuel can be injected into the internal combustion engine through a fuel injection valve using a piezo injector connected to the common rail. A pressure sensor diagnosis method in a common rail fuel injection control device, wherein the pressure is configured to be controllable based on a detection signal of a pressure sensor that detects the pressure of the common rail,
Applying a predetermined drive current to the piezo injector for a predetermined drive time, acquiring a change in a predetermined section of the terminal voltage of the piezo injector that occurs during the energization period, and determining the predetermined terminal voltage of the acquired piezo injector A standard rail pressure to be generated with respect to a change in the section is obtained based on a predetermined correlation between the predetermined change in the terminal voltage and the standard rail pressure,
When the difference between the detected rail pressure obtained by the pressure sensor and the standard rail pressure obtained based on the predetermined correlation is greater than a predetermined threshold, it is determined that the pressure sensor is abnormal. A pressure sensor diagnostic method. The change in the terminal voltage of the piezo injector in a predetermined section is the first peak voltage that appears after the start of energization of the predetermined drive current in the pulsation of the terminal voltage of the piezo injector that occurs during the energization period of the piezo injector to the predetermined drive time. The pressure sensor diagnosis method according to claim 1, wherein the potential difference is a difference in potential between the first and second peak voltages. The change in the terminal voltage of the piezo injector in a predetermined section is the first peak voltage that appears after the start of energization of the predetermined drive current in the pulsation of the terminal voltage of the piezo injector that occurs during the energization period of the piezo injector to the predetermined drive time. The pressure sensor diagnosis method according to claim 1, wherein a potential difference between the first peak voltage and the second peak voltage is a ratio of the first peak voltage to the first peak voltage. The difference between the detected rail pressure obtained by the pressure sensor and the standard rail pressure obtained based on a predetermined correlation is greater than a predetermined threshold in order for each piezo injector provided corresponding to the cylinder of the engine. In a piezo injector exceeding a predetermined number, the difference between the detected rail pressure obtained by the pressure sensor and the standard rail pressure obtained based on a predetermined correlation is greater than a predetermined threshold value. The pressure sensor diagnosis method according to any one of claims 1 to 3, wherein, when judged, the pressure sensor is abnormal. The pressure sensor diagnosis method according to any one of claims 1 to 4, wherein when a driving state of the engine is stable, energization of the piezo injector with a predetermined drive current is started. 6. The engine operating state is determined based on at least one of an engine cooling water temperature change amount, a fuel temperature change amount, and an accelerator opening degree. Pressure sensor diagnostic method. The fuel in the fuel tank is pressurized and pumped to a common rail by a high-pressure pump, and high-pressure fuel can be injected into the internal combustion engine via a fuel injection valve using a piezo injector connected to the common rail. The common rail fuel injection control device is configured so that the pressure of the common rail can be controlled based on a detection signal of a pressure sensor that detects the pressure of the common rail.
The electronic control unit is
Applying a predetermined drive current to the piezo injector for a predetermined drive time, acquiring a change in a predetermined section of the terminal voltage of the piezo injector that occurs during the energization period, and determining the predetermined terminal voltage of the acquired piezo injector A standard rail pressure to be generated for a change in the section is calculated based on a predetermined correlation between the predetermined change in the terminal voltage and the standard rail pressure,
It is determined whether the difference between the detected rail pressure obtained by the pressure sensor and the standard rail pressure obtained based on a predetermined correlation is greater than a predetermined threshold, and the detection obtained by the pressure sensor A common rail fuel characterized by determining that the pressure sensor is abnormal when it is determined that a difference between the rail pressure and a standard rail pressure obtained based on a predetermined correlation is greater than a predetermined threshold. Injection control device. The change in the terminal voltage of the piezo injector in a predetermined section is the first peak voltage that appears after the start of energization of the predetermined drive current in the pulsation of the terminal voltage of the piezo injector that occurs during the energization period of the piezo injector to the predetermined drive time. The common rail fuel injection control device according to claim 7, wherein the potential difference is between the first peak voltage and the second peak voltage. The change in the terminal voltage of the piezo injector in a predetermined section is the first peak voltage that appears after the start of energization of the predetermined drive current in the pulsation of the terminal voltage of the piezo injector that occurs during the energization period of the piezo injector to the predetermined drive time. 8. The common rail fuel injection control device according to claim 7, wherein the potential difference between the first peak voltage and the second peak voltage is a ratio of the first peak voltage to the first peak voltage. Electronic control unit
The difference between the detected rail pressure obtained by the pressure sensor and the standard rail pressure obtained based on a predetermined correlation is greater than a predetermined threshold in order for each piezo injector provided corresponding to the cylinder of the engine. In a piezoelectric injector exceeding a predetermined number, the difference between the detected rail pressure obtained by the pressure sensor and the standard rail pressure obtained based on a predetermined correlation is greater than a predetermined threshold. The common rail fuel injection control device according to any one of claims 7 to 9, wherein when determined, the pressure sensor is determined to be abnormal. The electronic control unit determines whether the engine operating state is stable,
11. The apparatus according to claim 7, wherein when the operating state of the engine is determined to be stable, energization with a predetermined drive current to the piezo injector is started. Common rail fuel injection control device. Electronic control unit
The engine is configured to determine whether or not the engine operating state is stable based on at least one of an engine coolant water temperature variation, a fuel temperature variation, and an accelerator opening. The common rail fuel injection control device according to claim 11. The fuel in the fuel tank is pressurized and pumped to the common rail by a high-pressure pump, and high-pressure fuel can be injected into the internal combustion engine through a fuel injection valve using a piezo injector connected to the common rail. A pressure sensor diagnosis method in a common rail fuel injection control device, wherein the pressure is configured to be controllable based on a detection signal of a pressure sensor that detects the pressure of the common rail,
Pressure sensor diagnosis characterized by determining whether or not there is an abnormality in the pressure sensor based on a first peak voltage in a pulsation of a terminal voltage that occurs after the start of energization of the piezo injector and a terminal voltage at the end of energization of the piezo injector Method. It is characterized that it is determined that the pressure sensor is abnormal when the difference between the first peak voltage in the pulsation of the terminal voltage generated after the start of energization of the piezo injector and the terminal voltage at the end of energization of the piezo injector exceeds a predetermined threshold. The pressure sensor diagnostic method according to claim 13. The fuel in the fuel tank is pressurized and pumped to the common rail by a high-pressure pump, and high-pressure fuel can be injected into the internal combustion engine through a fuel injection valve using a piezo injector connected to the common rail. A pressure sensor diagnosis method in a common rail fuel injection control device, wherein the pressure is configured to be controllable based on a detection signal of a pressure sensor that detects the pressure of the common rail,
Whether the pressure sensor is abnormal is determined based on a terminal voltage of the piezo injector at the end of energization of the piezo injector and a target voltage of the terminal voltage of the piezo injector at the end of energization. Pressure sensor diagnostic method. Determining that the pressure sensor is abnormal when a difference between a terminal voltage of the piezo injector at the end of energization of the piezo injector and a target voltage of the terminal voltage of the piezo injector at the end of energization exceeds a predetermined threshold. The pressure sensor diagnostic method according to claim 15, wherein: The fuel in the fuel tank is pressurized and pumped to the common rail by a high-pressure pump, and high-pressure fuel can be injected into the internal combustion engine through a fuel injection valve using a piezo injector connected to the common rail. The pressure is configured to be controllable based on a detection signal of a pressure sensor that detects the pressure of the common rail, and the piezo injector is configured so that the terminal voltage at the end of energization becomes a predetermined target voltage. A pressure sensor diagnostic method in a common rail fuel injection control device configured to be driven and controlled by correcting an applied voltage of a piezo injector,
A pressure sensor diagnosis method, comprising: determining whether the pressure sensor is abnormal when a correction amount of an applied voltage at the end of energization of the piezo injector exceeds a predetermined amount. 18. The presence / absence of an abnormality in the pressure sensor is determined when an average value of correction amounts for a predetermined number of corrections and an absolute value of a difference between the latest correction amounts exceed a predetermined predetermined amount. Pressure sensor diagnostic method. The fuel in the fuel tank is pressurized and pumped to a common rail by a high-pressure pump, and high-pressure fuel can be injected into the internal combustion engine via a fuel injection valve using a piezo injector connected to the common rail. The common rail fuel injection control device is configured so that the pressure of the common rail can be controlled based on a detection signal of a pressure sensor that detects the pressure of the common rail.
The electronic control unit is
The pressure sensor is configured to determine whether or not the pressure sensor is abnormal based on an initial peak voltage in the pulsation of the terminal voltage generated after the start of energization of the piezo injector and a terminal voltage at the end of energization of the piezo injector. A common rail fuel injection control device. When the difference between the initial peak voltage in the pulsation of the terminal voltage generated after the start of energization of the piezo injector and the terminal voltage at the end of energization of the piezo injector exceeds a predetermined threshold, the electronic control unit 20. The common rail fuel injection control device according to claim 19, wherein the common rail fuel injection control device is configured to make a determination. The fuel in the fuel tank is pressurized and pumped to a common rail by a high-pressure pump, and high-pressure fuel can be injected into the internal combustion engine via a fuel injection valve using a piezo injector connected to the common rail. The common rail fuel injection control device is configured so that the pressure of the common rail can be controlled based on a detection signal of a pressure sensor that detects the pressure of the common rail.
The electronic control unit is
Obtaining the terminal voltage of the piezo injector at the end of energization to the piezo injector, and based on the obtained terminal voltage of the piezo injector and the target voltage of the terminal voltage of the piezo injector at the end of energization of the piezo injector The common rail fuel injection control device is configured to determine whether or not the pressure sensor is abnormal. The electronic control unit takes a terminal voltage of the piezo injector at the end of energization of the piezo injector and a difference between a target voltage of the terminal voltage of the piezo injector at the end of energization of the piezo injector exceeds a predetermined threshold 22. The common rail fuel injection control device according to claim 21, wherein the common rail fuel injection control device is configured to determine that the pressure sensor is abnormal. The fuel in the fuel tank is pressurized and pumped to a common rail by a high-pressure pump, and high-pressure fuel can be injected into the internal combustion engine via a fuel injection valve using a piezo injector connected to the common rail. Thus, the pressure of the common rail is configured to be controllable based on a detection signal of a pressure sensor that detects the pressure of the common rail, and the terminal voltage at the end of energization of the piezo injector is a predetermined target voltage. A common rail fuel injection control device configured to control the drive of the piezo injector by correcting the applied voltage of the piezo injector,
The electronic control unit is
It is determined whether the correction amount of the applied voltage at the end of energization of the piezo injector exceeds a predetermined amount, and when it is determined that the correction amount of the applied voltage at the end of energization of the piezo injector exceeds a predetermined amount, A common rail fuel injection control device configured to determine that the pressure sensor is abnormal. The electronic control unit calculates an average value of correction amounts for a predetermined number of correction times, determines whether or not an absolute value of a difference between the average value and the latest correction amount exceeds a predetermined amount, and the absolute value is 24. The common rail fuel injection control device according to claim 23, wherein the common rail fuel injection control device is configured to determine that the pressure sensor is abnormal when it is determined that the predetermined amount is exceeded. The fuel in the fuel tank is pressurized and pumped to the common rail by a high-pressure pump, and high-pressure fuel can be injected into the internal combustion engine through a fuel injection valve using a piezo injector connected to the common rail. A pressure sensor diagnosis method in a common rail fuel injection control device, wherein the pressure is configured to be controllable based on a detection signal of a pressure sensor that detects the pressure of the common rail,
A pressure sensor diagnostic method, wherein the presence or absence of an abnormality of the pressure sensor is determined based on a change in the terminal voltage within a predetermined section in a pulsation of a terminal voltage generated after the energization of the piezo injector is started.

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