JP7749141B2 - Electronic control unit - Google Patents

Description

The present disclosure relates to electronic control devices.

BACKGROUND ART There are known inventions relating to high-pressure fuel supply devices for internal combustion engines, fuel injection control devices, and fuel supply control devices for internal combustion engines (see Patent Documents 1 to 3 listed below).

The high-pressure fuel supply device for an internal combustion engine described in Patent Document 1 below includes a high-pressure pump that pressurizes fuel transferred from a fuel tank, a fuel pressure sensor that detects the pressure of the pressurized fuel, and an injection valve that injects the pressurized fuel into the internal combustion engine (paragraph 0011, claim 1, abstract, and figure 1). This conventional high-pressure fuel supply device for an internal combustion engine supplies a predetermined amount of high-pressure fuel to the internal combustion engine through the injection valve according to its operating state, while feedback-controlling the pressurized fuel pressure so that the detected fuel pressure becomes a target pressure.

This conventional high-pressure fuel supply device for an internal combustion engine is characterized by comprising a detection means, a holding means, and a control means. The detection means detects an abnormality in the fuel pressure sensor. The holding means forcibly holds the fuel pressure at a predetermined pressure based on the detection of an abnormality in the fuel pressure sensor. After the abnormality in the fuel pressure sensor is detected, the control means estimates the fuel pressure and controls the amount of fuel injected and supplied to the internal combustion engine based on the estimated fuel pressure until the fuel pressure reaches the predetermined pressure.

The fuel injection control device disclosed in the following Patent Document 2 includes an injector that injects fuel into an internal combustion engine, a fuel pressure sensor that detects the pressure of the fuel supplied to the injector, various sensors that detect the operating state of the internal combustion engine, and a fuel supply control unit that calculates the amount of fuel supplied based on signals from the fuel pressure sensor and various sensors and controls the drive of the injector (paragraph 0009, claim 1, abstract, and figure 2). The fuel supply control unit includes an injector valve opening signal generating means, a first drive current supply signal generating means, a first drive current supplying means, a second drive current supplying means, and a fuel pressure sensor failure detecting means.

The injector valve-opening signal generating means calculates a fuel supply amount based on signals from the various sensors and outputs an injector valve-opening signal based on the fuel supply amount. The first drive current supply signal generating means sets a first drive current supply time for supplying a first drive current to the injector valve-opening timing based on a signal from the fuel pressure sensor and outputs a first drive current supply signal. The first drive current supply means supplies a first drive current to the injector based on the injector valve-opening signal from the injector valve-opening signal generating means and the first drive current supply signal from the first drive current supply signal generating means.

The second drive current supplying means supplies a second drive current lower than the first drive current to the injector based on an injector valve-opening signal from the injector valve-opening signal generating means after supplying the first drive current. The fuel pressure sensor failure detecting means detects a failure of the fuel pressure sensor based on a signal from the fuel pressure sensor. The first drive current supply signal generating means sets the first drive current supply time to a predetermined fixed time when the fuel pressure sensor failure detecting means detects a failure of the fuel pressure sensor.

The fuel supply control device for an internal combustion engine described in Patent Document 3 below detects the fuel pressure in a fuel supply pipe that supplies fuel from a fuel pump to a fuel injection valve, and controls the fuel pump so that the detected fuel pressure approaches a target fuel pressure. This conventional fuel supply control device for an internal combustion engine has a response characteristic calculation means, an operation amount calculation means, a control means, a diagnosis means, and a setting means (paragraphs 0020 to 0028, claim 1).

The response characteristic calculation means calculates an operational response characteristic of the fuel pump for controlling the fuel pressure to the target fuel pressure. The manipulated variable calculation means calculates an operational variable of the fuel pump according to the operational response characteristic calculated by the response characteristic calculation means. The control means controls the fuel pump based on the operational variable calculated by the manipulated variable calculation means. The diagnosis means diagnoses a failure of a sensor that detects fuel pressure in the fuel supply pipe.

When the diagnosing means diagnoses that no failure has occurred in the sensor, the setting means sets the fuel pressure corresponding to the operating state of the internal combustion engine as the target fuel pressure and sets the fuel pressure detected by the sensor as the fuel pressure for fuel injection control.On the other hand, when the diagnosing means diagnoses that a failure has occurred in the sensor, the setting means sets the target fuel pressure to a predetermined pressure for failure and sets the operation response characteristic as the fuel pressure for fuel injection control.

Japanese Patent Application Publication No. 11-210532 Japanese Patent Application Laid-Open No. 2007-138772 JP 2013-064378 A

The pressure of fuel supplied to the injector that injects fuel into the engine (fuel pressure) is now required to be increased to, for example, about 35 MPa. Therefore, it is necessary to control the injector so that the drive current increases in accordance with the increased fuel pressure. However, if the fuel pressure sensor that detects the fuel pressure fails or an abnormality occurs in the detected fuel pressure, the drive power of the injector is calculated to be too low based on the abnormal fuel pressure, which can result in the injector valve not opening properly, causing the internal combustion engine to stop or reduce its rotation speed.

The present disclosure provides an electronic control device that can prevent the injector from failing to open when a fuel pressure sensor that detects the pressure of fuel supplied to the injector fails or an abnormal detection value occurs, thereby preventing the engine from stopping or decreasing in rotation speed.

One aspect of the present disclosure is an electronic control device for controlling an engine system including an injector that injects fuel into a combustion chamber of an engine and a fuel pressure sensor that detects the fuel pressure of the fuel supplied to the injector, the electronic control device including: a target fuel pressure calculation unit that calculates a target fuel pressure of the fuel supplied to the injector; a fuel pressure acquisition unit that acquires a fuel pressure detection value of the fuel pressure sensor; a failure detection unit that detects a failure of the fuel pressure sensor based on the fuel pressure detection value; a failure determination unit that determines a failure of the fuel pressure sensor when the detection of the fuel pressure sensor failure continues beyond a first period; and a difference between the target fuel pressure and the fuel pressure detection value and a unit time of the fuel pressure detection value. an abnormality determination unit that determines that the detected fuel pressure value is abnormal if the abnormality in the detected fuel pressure value continues beyond a second period; and a drive current setting unit that sets a drive current for the injector, wherein the drive current setting unit sets a provisional drive current corresponding to the fuel pressure detected value at a time before the fuel pressure sensor failure or the detected value abnormality is detected, as the drive current for the injector during the period from the detection of the fuel pressure sensor failure or the detected value abnormality to the confirmation of the fuel pressure sensor failure or the detected value abnormality.

According to the above-described aspect of the present disclosure, an electronic control device can be provided that can prevent the injector from failing to open when a fuel pressure sensor that detects the fuel pressure of the fuel supplied to the injector fails or an abnormal detection value occurs, thereby preventing the engine from stopping or decreasing in rotation speed.

1 is a schematic configuration diagram of an engine system illustrating an embodiment of an electronic control device of the present disclosure. FIG. 2 is a schematic diagram of a fuel supply system of the engine system of FIG. 1 . FIG. 2 is a block diagram showing a schematic configuration of the electronic control device shown in FIG. 1 ; FIG. 2 is a functional block diagram of the electronic control device of FIG. 1 . FIG. 5 is a flowchart illustrating a control process of the engine system by the electronic control device of FIG. 4 . 5 is a timing chart showing the control of the engine system by the electronic control device of FIG. 4 . FIG. 6 is a flowchart showing details of the process (P08) when a failure or the like is detected in FIG. 5; FIG. 6 is a flowchart showing details of the failure etc. determination process (P09) in FIG. 5 . FIG. 6 is a flowchart showing details of the failure confirmation process (P10) in FIG. 5; FIG. 8 is a flowchart showing a first modification of the process (P08) when a failure or the like is detected in FIG. 7; FIG. 8 is a flowchart showing a second modification of the process (P08) when a failure or the like is detected in FIG. 7; FIG. 5 is a functional block diagram showing a first modified example of the electronic control device shown in FIG. 4 . FIG. 13 is a flowchart illustrating the operation of the electronic control device of the first modified example shown in FIG. 12 . 13 is a timing chart illustrating the operation of the electronic control device of the first modified example shown in FIG. 12 . FIG. 5 is a functional block diagram showing a second modification of the electronic control device shown in FIG. 4 . FIG. 16 is a flowchart illustrating the operation of the electronic control device of the second modified example shown in FIG. 15 . 16 is a timing chart illustrating the operation of the electronic control device of the second modified example shown in FIG. 15 . FIG. 5 is a functional block diagram showing a third modified example of the electronic control device shown in FIG. 4 . FIG. 19 is a flowchart illustrating the operation of the electronic control device of the third modified example shown in FIG. 18 . 19 is a timing chart illustrating the operation of the electronic control device of the third modified example shown in FIG. 18 .

1 is a schematic diagram of an engine system ES showing one embodiment of an electronic control device according to the present disclosure. The engine system ES is mounted on, for example, a vehicle and generates power to drive the vehicle. The engine system ES includes, for example, an intake system 1, a fuel supply system 2, an engine 3, an exhaust system 4, an electronic control unit 5, and an accelerator position sensor 6. In the following description, the electronic control unit 5 will be abbreviated as "ECU 5" where appropriate.

The intake system 1 includes, for example, an intake sensor 11, a throttle valve 12, a collector 13, and an intake manifold 14. The intake sensor 11 detects physical quantities such as the flow rate, temperature, humidity, and pressure of air taken into the intake system 1. The intake sensor 11 is connected to the ECU 5 via wiring and outputs the detected physical quantities to the ECU 5.

The throttle valve 12 includes a valve element, an opening sensor that detects the opening of the valve element, and a motor that drives the valve element. The throttle valve 12 is connected to the ECU 5 via wiring, and the opening is controlled by the ECU 5. A collector 13 distributes the air flowing in through the throttle valve 12 to each branch of the intake manifold 14. The intake manifold 14 supplies the air distributed by the collector 13 to the combustion chamber 31 of the engine 3. The intake manifold 14 is equipped with, for example, an intake pipe pressure sensor (not shown), which detects the pressure of the intake air and outputs the result of that detection to the ECU 5.

Fig. 2 is a schematic diagram of the fuel supply system 2 of the engine system ES of Fig. 1. The fuel supply system 2 includes, for example, a fuel tank 21, a low-pressure fuel pump 22, a regulator 23, a low-pressure fuel supply pipe 24 (low-pressure fuel supply passage), a high-pressure fuel pump 25, a high-pressure fuel supply pipe 26, a common rail 27, a fuel pressure sensor 28, and an injector 29. The fuel tank 21 stores fuel such as gasoline. The low-pressure fuel pump 22 supplies low-pressure fuel to the high-pressure fuel pump 25 or the common rail 27 via the low-pressure fuel supply pipe 24.

When the pressure of the fuel in the low-pressure fuel supply pipe 24 reaches or exceeds a predetermined level, the regulator 23 returns the fuel in the low-pressure fuel supply pipe 24 to the fuel tank 21, thereby regulating the pressure of the fuel in the low-pressure fuel supply pipe 24 to a constant level. The high-pressure fuel pump 25 is driven, for example, by power transmitted from a camshaft of an exhaust cam that drives an exhaust valve 34 of the engine 3. The high-pressure fuel pump 25 increases the pressure of the fuel supplied from the low-pressure fuel pump 22, and supplies the high-pressure fuel to a common rail 27 via a high-pressure fuel supply pipe 26.

The common rail 27 supplies high-pressure fuel supplied from the high-pressure fuel pump 25 via a high-pressure fuel supply pipe 26 to a plurality of injectors 29. The fuel pressure sensor 28, for example, detects the pressure of the fuel supplied to the common rail 27 (fuel pressure). The fuel pressure sensor 28 is connected to the ECU 5, for example, via a wire, and outputs the detection result of the fuel pressure to the ECU 5. The injectors 29 are provided, for example, in each cylinder of the engine 3 and connected to the ECU 5 via a wire. The injectors 29 are controlled by the ECU 5 and inject the fuel supplied from the common rail 27 into the combustion chambers 31 of each cylinder of the engine 3.

The engine 3 is, for example, a four-cylinder engine having four cylinders. The engine 3 is not limited to a direct injection type, and may be, for example, a port injection type or a dual injection type spark ignition internal combustion engine that combines direct injection and port injection. The engine 3 includes, for example, a combustion chamber 31, a piston 32, an intake valve 33, an exhaust valve 34, an ignition coil 35, a spark plug 36, a crank angle sensor 37, and a water temperature sensor 38.

The combustion chamber 31 is a space where a mixture of fuel injected by the injector 29 and air supplied from the intake manifold 14 via an intake valve 33 is combusted. The piston 32 is pushed down by the combustion of the mixture in the combustion chamber 31, causing the crankshaft to rotate. The actuators for the intake valve 33 and the exhaust valve 34 are connected to the ECU 5, for example, via wiring. The actuators for the intake valve 33 and the exhaust valve 34 open and close the intake valve 33 and the exhaust valve 34, respectively, under the control of the ECU 5, for example.

The ignition coil 35 is connected to the ECU 5, for example, via wiring. The ignition coil 35 generates a high voltage under the control of the ECU 5. The spark plug 36 ignites the air-fuel mixture in the combustion chamber 31 by discharging the high voltage generated by the ignition coil 35. The crank angle sensor 37 detects the angle of the crankshaft of the engine 3. The crank angle sensor 37 is connected to the ECU 5, for example, via wiring, and outputs the angle detection result to the ECU 5. The water temperature sensor 38 detects the temperature of the cooling water of the engine 3. The water temperature sensor 38 is connected to the ECU 5, for example, via wiring, and outputs the temperature detection result to the ECU 5.

The exhaust system 4 includes, for example, an exhaust manifold 41, an oxygen sensor 42, and a three-way catalyst 43. The exhaust manifold 41 collects exhaust gas discharged from the combustion chambers 31 of each cylinder via the exhaust valves 34. The oxygen sensor 42 detects the oxygen concentration of the exhaust gas that has passed through the exhaust manifold 41. The oxygen sensor 42 is connected to the ECU 5, for example, via wiring, and outputs the detected oxygen concentration to the ECU 5. The three-way catalyst 43 purifies harmful components in the exhaust gas through oxidation and reduction.

The ECU 5 is an engine control unit that is responsible for overall control of the engine system ES, including, for example, fuel injection by the injectors 29. The ECU 5 calculates the amount of fuel injected by the injectors 29 and other parameters based on engine state quantities, including, for example, the crank rotation angle, throttle opening, engine speed, and fuel pressure, which are obtained from various sensors of the engine system ES, and controls the high-pressure fuel pump 25, the injectors 29, and other parameters.

Fig. 3 is a block diagram showing a schematic configuration of the ECU 5 in Fig. 1. The ECU 5 is configured by a computer including, for example, an input circuit 51, an A/D conversion unit 52, a central processing unit (CPU) 53, a ROM 54, a RAM 55, and an output circuit 56. Note that the ECU 5 can also be configured by an FPGA (Field Programmable Gate Array), which is a rewritable logic circuit, an ASIC (Application Specific Integrated Circuit), which is an application specific integrated circuit, or a combination of a ROM, a RAM, and an FPGA.

The input circuit 51 receives signals SS1, SS2, SS3, etc. output from various sensors, such as the intake sensor 11, the throttle valve 12 opening sensor, the fuel pressure sensor 28, the crank angle sensor 37, the water temperature sensor 38, the oxygen sensor 42, and the accelerator position sensor 6. If the input signal is an analog signal, the input circuit 51 removes noise from the analog signal and outputs the noise-removed analog signal to the A/D converter 52. If the input signal is a digital signal, the input circuit 51 outputs the digital signal as is to the CPU 53. The A/D converter 52 converts the analog signal input from the input circuit 51 into a digital signal and outputs the digital signal to the CPU 53.

The CPU 53 executes control logic such as a program stored in the ROM 54 to perform various calculations, diagnoses, and controls using the detection results of each sensor input as digital signals from the input circuit 51 or the A/D conversion unit 52. The CPU 53 temporarily stores the detection results of each sensor, calculation results, diagnosis results, etc. in the RAM 55. The CPU 53 outputs control signals CS1, CS2, CS3, ... including drive currents for the injectors 29 to each unit of the engine system ES, including the injectors 29, via the output circuit 56, based on the calculation results and diagnosis results.

4 is a functional block diagram showing details of the function of outputting the drive current I of the injector 29 in the ECU 5 of FIG. 1. The ECU 5 includes, for example, a target fuel pressure calculation unit 501, a fuel pressure acquisition unit 502, a fault detection unit 503, a fault determination unit 504, an abnormality detection unit 505, an abnormality determination unit 506, and a drive current setting unit 507. In the example shown in FIG. 4, the ECU 5 also includes, for example, a fail-safe processing unit 508, a high-pressure fuel pump control unit 509, a drive current calculation unit 510, and a drive current output unit 511. Note that the respective units of the ECU 5 shown in FIG. 4 represent the respective functions of the ECU 5 realized by, for example, the CPU 53 shown in FIG. 3 executing a program stored in the ROM 54.

Fig. 5 is a flow chart illustrating a control process P of the engine system ES by the ECU 5 of Fig. 4. Fig. 6 is a timing chart when the engine system ES is controlled by the ECU 5 shown in Fig. 4.

6 represents time, and the vertical axis of the top chart represents whether or not a malfunction (fuel pressure sensor malfunction) or an abnormal detected value has been detected in fuel pressure sensor 28. The vertical axis of the second chart from the top of Fig. 6 represents the fuel pressure of fuel supplied to injector 29, with the solid line representing the actual fuel pressure FPr and the dashed dotted line representing the fuel pressure detected value FPs by fuel pressure sensor 28.

The vertical axis of the second chart from the bottom in Fig. 6 is the drive current input to the injector 29, with the solid line representing the drive current controlled by the ECU 5 of this embodiment and the dashed line representing the drive current controlled by the conventional device. The vertical axis of the bottom chart in Fig. 6 is the engine speed of the engine 3, with the solid line representing the engine speed controlled by the ECU 5 of this embodiment and the dashed line representing the engine speed controlled by the conventional device.

The operation of each part of the ECU 5 shown in Fig. 4 will be described below while describing each step of the control process shown in Fig. 5. When the ECU 5 starts the control process P shown in Fig. 5, it executes, for example, a process P01 for calculating a target fuel pressure FPt. In this process P01, a target fuel pressure calculation unit 501 calculates a target fuel pressure FPt of fuel supplied to the injector 29 based on, for example, the intake air amount Qa input to the ECU 5 from the intake sensor 11, the engine speed Ne of the engine 3 based on the rotation angle input to the ECU 5 from the crank angle sensor 37, and the like.

Next, the ECU 5 executes, for example, a process P02 for acquiring the fuel pressure. In this process P02, the fuel pressure acquisition unit 502 acquires, for example, the fuel pressure detection value FPs input from the fuel pressure sensor 28 to the ECU 5. Next, the ECU 5 executes, for example, a process P03 for controlling the high-pressure fuel pump 25.

In process P03, high-pressure fuel pump control unit 509 controls the amount of fuel discharged by high-pressure fuel pump 25 based on signal SS input from, for example, accelerator position sensor 6, an opening sensor of throttle valve 12, crank angle sensor 37, etc. In this way, the pressure of the fuel supplied to injector 29, i.e., the fuel pressure, is controlled to a desired pressure. Here, high-pressure fuel pump control unit 509 may, for example, feedback control the amount of fuel discharged by high-pressure fuel pump 25 so that fuel pressure detection value FPs from fuel pressure sensor 28 matches target fuel pressure FPt.

Next, ECU 5 executes, for example, process P04 for calculating a drive current for injector 29. In process P04, drive current calculation unit 510 calculates a drive current for injector 29 based on, for example, fuel pressure detection value FPs of fuel pressure sensor 28 acquired by fuel pressure acquisition unit 502. Drive current calculation unit 510 also calculates a drive current for injector 29 based on, for example, target fuel pressure FPt calculated by target fuel pressure calculation unit 501 and detected fuel pressure value FPs. More specifically, drive current calculation unit 510 calculates the drive current for injector 29 based on, for example, the difference between target fuel pressure FPt and detected fuel pressure value FPs.

Next, the ECU 5 executes a process P05 in which it determines whether or not a fuel pressure sensor malfunction or an abnormality in the detected value has been detected. In this process P05, the malfunction detection unit 503 detects a fuel pressure sensor malfunction, i.e., a malfunction of the fuel pressure sensor 28, based on the fuel pressure detection value FPs of the fuel pressure sensor 28 acquired by the fuel pressure acquisition unit 502. Here, the fuel pressure sensor malfunction detected by the malfunction detection unit 503 includes, for example, a ground fault or a broken wire in the fuel pressure sensor 28.

In step P05, the abnormality detection unit 505 detects an abnormality in the detected fuel pressure value FPs based on the detected fuel pressure value FPs of the fuel pressure sensor 28 acquired by the fuel pressure acquisition unit 502 and the target fuel pressure FPt calculated by the target fuel pressure calculation unit 501. An abnormality in the detected fuel pressure value FPs of the fuel pressure sensor 28, i.e., an abnormality in the detected fuel pressure value FPs, detected by the abnormality detection unit 505, is, for example, a state in which the difference between the target fuel pressure FPt and the detected fuel pressure value FPs and the amount of change in the detected fuel pressure value FPs per unit time exceed predetermined thresholds. Such an abnormality in the detected fuel pressure value can be caused by, for example, an abnormality in the microcontroller or an input abnormality.

For example, as shown in Figure 6, if no malfunction occurs in the fuel pressure sensor 28 or an abnormality in the fuel pressure detection value FPs occurs until time t1, the malfunction detection unit 503 determines that no malfunction of the fuel pressure sensor or an abnormality in the detection value has been detected (NO) in process P05 before time t1.

In this case, the ECU 5 executes a process P06 for setting a drive current for the injector 29. In this process P06, the drive current setting unit 507 sets a drive current for the injector 29 based on the detected fuel pressure value FPs. More specifically, the drive current setting unit 507 sets the drive current based on the detected fuel pressure value FPs calculated by the drive current calculation unit 510 as the drive current to be output next to the injector 29, until a fuel pressure sensor failure or an abnormal detected value is detected in process P05, for example.

Next, the ECU 5 executes a process P07 for outputting a drive current, for example. In this process P07, the drive current output unit 511 outputs the drive current set by the drive current setting unit 507 to the injector 29. As a result, the injector 29 opens in response to the drive current input from the ECU 5. As a result, as shown in FIGS. 1 and 2 , high-pressure fuel is supplied from the fuel tank 21 by the low-pressure fuel pump 22 to the high-pressure fuel pump 25, and then pressurized by the high-pressure fuel pump 25 and discharged to the common rail 27. The high-pressure fuel is then injected from the injector 29 into the combustion chamber 31 of the engine 3.

The injector 29 is, for example, an in-cylinder direct injection injector that injects fuel multiple times during one cycle of the engine 3. The injector 29 injects fuel into the combustion chamber 31 by opening its valve for a time period specified by a drive current input from the ECU 5. The total fuel injection amount, which is the total amount of fuel injected by the injector 29 during one cycle, can be set in advance, and the injection amount for each of the multiple fuel injections can also be set in advance.

Thereafter, the ECU 5 repeatedly executes the above-described steps P01 to P07 at a predetermined interval until, for example, time t1 shown in Figure 6. Suppose that at time t1, a malfunction of the fuel pressure sensor 28 or an abnormality in the detected fuel pressure value FPs occurs, causing the detected fuel pressure value FPs of the fuel pressure sensor 28, indicated by the dashed line, to suddenly drop, as shown in the second chart from the top in Figure 6. Then, the difference between the detected fuel pressure value FPs and the actual fuel pressure FPr of the fuel supplied to the injector 29, indicated by the solid line, increases.

5, immediately after time t1, the ECU 5 determines whether the failure detection unit 503 has detected a fuel pressure sensor failure (YES), or whether the abnormality detection unit 505 has detected an abnormality in the detected value (YES). In this case, the ECU 5 executes, for example, a failure detection process P08, a failure determination process P09, and a failure determination process P10, as shown in FIG.

7 is a flowchart showing details of the process P08 when a malfunction or the like is detected in FIG. When the ECU 5 starts this process P08, it first executes a process P081 to determine whether a confirmation determination of a fuel pressure sensor malfunction is currently being executed. In this process P081, the malfunction determination unit 504 determines that a confirmation determination of a fuel pressure sensor malfunction is not currently being executed (NO) if, for example, the malfunction detection unit 503 has not detected a fuel pressure sensor malfunction or if a fuel pressure sensor malfunction has already been confirmed.

In this case, the ECU 5 executes, for example, a process P082 for determining whether a determination of an abnormal detected value is currently being performed. In this process P082, the abnormality determination unit 506 determines that a determination of an abnormal detected value is not currently being performed (NO) if, for example, the abnormality detection unit 505 has not detected an abnormal detected value or if an abnormal detected value has already been determined. In this case, the ECU 5 ends process P08 shown in FIG. 7 and executes the next malfunction or other malfunction determination process P09.

On the other hand, in process P081, the fault determination unit 504 determines that a determination of a fuel pressure sensor fault is being executed (YES) if the state (Y) in which the fault detection unit 503 has detected a fuel pressure sensor fault continues and the state has not exceeded the first period TP1, as shown in the top chart of Fig. 6. Similarly, in process P082, the abnormality determination unit 506 determines that a determination of a detected value abnormality is being executed (YES) if the state (Y) in which the abnormality detection unit 505 has detected a detected value abnormality continues and the state has not exceeded the second period TP2.

In these cases, the ECU 5 executes the next process P083. The first period TP1 for determining whether the fuel pressure sensor is malfunctioning and the second period TP2 for determining whether the detected value is abnormal can be set to any period necessary to determine the respective events. Therefore, the first period TP1 and the second period TP2 may be the same or different. For ease of explanation, in FIG. 6, the first period TP1 and the second period TP2 are shown as the same period from time t1 to time t2.

In process P083, the ECU 5 sets a provisional drive current based on the fuel pressure detection value FPs at a time before the detection of the failure or abnormality. In this process P083, the drive current setting unit 507 sets, for example, as the drive current to be output next to the injector 29, a provisional drive current that is different from the drive current based on the fuel pressure detection value FPs of the fuel pressure sensor 28 after the detection of the fuel pressure sensor failure or abnormality.

More specifically, in process P083, drive current setting unit 507 sets, for example, a provisional drive current based on the fuel pressure detection value FPs at a time point before time t1 when a fuel pressure sensor failure or an abnormal detection value is detected, as the drive current to be output next to injector 29. For example, drive current setting unit 507 sets the drive current set in the process immediately before time t1 when a fuel pressure sensor failure or an abnormal detection value is detected, as the provisional drive current.

As a result, as shown by the solid line in the second chart from the bottom in Figure 6, even after time t1 when a fuel pressure sensor failure or an abnormality in the detected value is detected and the detected fuel pressure value FPs and the actual fuel pressure FPr begin to diverge, the drive current output from the ECU 5 to the injector 29 does not change significantly. As a result, it is possible to prevent the injector valve from failing to open when a failure or an abnormality in the detected value occurs in the fuel pressure sensor 28. Therefore, as shown by the solid line in the bottom chart in Figure 6, it is possible to prevent the engine 3 from stalling or reducing its rotation speed even after time t1 when the detected fuel pressure value FPs of the fuel pressure sensor 28 begins to diverge from the actual fuel pressure FPr.

In contrast, in a conventional system, the injector drive current drops sharply in response to a sudden drop in the fuel pressure detected by the fuel pressure sensor after a fuel pressure sensor failure or abnormality occurs, as shown by the dashed line in the second chart from the bottom in Figure 6. As a result, in a conventional system, the drive current corresponding to the fuel pressure detected by the fuel pressure sensor deviates from the drive current corresponding to the actual fuel pressure of the fuel supplied to the injector. Therefore, in a conventional system, insufficient drive current can cause the injector valve to fail to open, which can lead to engine stalls or a drop in engine speed, as shown by the dashed line in the bottom chart in Figure 6.

Thereafter, the ECU 5 ends process P08 shown in Fig. 7 and executes the next malfunction determination process P09. Fig. 8 is a flow chart showing details of the malfunction determination process P09 shown in Fig. 5. When the ECU 5 starts process P09, it first executes process P091 in which it determines whether the duration of the fuel pressure sensor malfunction has exceeded a first period TP1. In process P091, the malfunction determination unit 504 makes a negative (NO) determination, for example, if the malfunction detection unit 503 has not detected a fuel pressure sensor malfunction, if the fuel pressure sensor malfunction has already been determined, or if the duration of the detected fuel pressure sensor malfunction has not exceeded the first period TP1.

The ECU 5 also executes a process P092 in which it is determined whether the duration of the abnormal detection value has exceeded the second period TP2. In this process P092, the abnormality determination unit 506 determines a negative (NO) result, for example, when the abnormality detection unit 505 has not detected an abnormal detection value, when the abnormal detection value has already been determined, or when the duration of the abnormal detection value detection has not exceeded the second period TP2. In this case, the ECU 5 ends the process P09 shown in FIG. 8 and executes the next malfunction confirmation process P10.

On the other hand, in process P091, the malfunction determination unit 504 makes an affirmative (YES) determination if the state (Y) in which the malfunction detection unit 503 has detected a malfunction in the fuel pressure sensor continues and this state has exceeded the first period TP1, for example, as shown in the top chart of Fig. 6. In this case, the malfunction determination unit 504 executes process P093 to determine that the fuel pressure sensor has malfunctioned, and then ends process P09 shown in Fig. 8.

Similarly, in process P092, the abnormality determination unit 506 determines affirmative (YES) if the state (Y) in which the abnormality detection unit 505 has detected an abnormality in the detected value continues and this state has exceeded the second period TP2. In this case, the abnormality determination unit 506 executes process P094 to determine the abnormality in the detected value, and ends process P09 shown in Figure 8. Thereafter, the ECU 5 executes the next malfunction confirmation process P10.

9 is a flowchart showing details of the failure confirmation process P10 in FIG. 5. When the ECU 5 starts this process, it first executes process P101 to determine whether a fuel pressure sensor failure or an abnormal detected value has been confirmed. In process P101, the fail-safe processing unit 508 makes a negative (NO) determination if, for example, the failure confirmation unit 504 has not confirmed a fuel pressure sensor failure or an abnormal detected value.

In this case, in the next process P103, the fail-safe processing unit 508 maintains the drive current to be output next to the injector 29 at the drive current previously output to the injector 29, and outputs this drive current to the drive current setting unit 507. Thereafter, the ECU 5 ends process P10 shown in Fig. 9 and executes processes P06 and P07 shown in Fig. 5. As a result, the drive current setting unit 507 sets a provisional drive current as the drive current to be output to the injector 29 during the period from the detection of a fuel pressure sensor failure or an abnormal detection value until it is confirmed, and thus the provisional drive current is output from the drive current output unit 511 to the injector 29.

On the other hand, in process P101, the failsafe processing unit 508 makes an affirmative (YES) determination, for example, when the malfunction determination unit 504 determines that the fuel pressure sensor is malfunctioning or that its detected value is abnormal. In this case, in the next process P102, the failsafe processing unit 508 determines whether the drive current to be output to the injector 29 next is greater than the set value when the fuel pressure sensor malfunction was determined. If the failsafe processing unit 508 determines in process P102 that the drive current is greater than the set value when the fuel pressure sensor malfunction was determined (YES), the failsafe processing unit 508 executes process P104, in which the drive current is gradually reduced and output to the drive current setting unit 507.

Thereafter, the ECU 5 ends the process P10 shown in FIG. 9, and executes the process P06 and the process P07 shown in FIG.

More specifically, for example, until a fuel pressure sensor failure or an abnormality in the detected value is detected, high-pressure fuel pump control unit 509 shown in FIG. 4 performs feedback control to set the amount of fuel discharged from high-pressure fuel pump 25 shown in FIGS. 1 and 2 to injector 29 based on the target fuel pressure FPt calculated by target fuel pressure calculation unit 501 and the fuel pressure detected value FPs of fuel pressure sensor 28. Furthermore, high-pressure fuel pump control unit 509 temporarily suspends feedback control of the fuel discharge amount during the period from detection of a fuel pressure sensor failure or an abnormal detected value to confirmation of the fuel pressure sensor failure or an abnormal detected value, and at that time can perform feedforward control of the fuel discharge amount based on the target fuel pressure FPt at a time before the fuel pressure sensor failure or an abnormal detected value was detected. Furthermore, when a fuel pressure sensor failure or an abnormal detected value is confirmed, high-pressure fuel pump control unit 509 suspends pressurized discharge of fuel from high-pressure fuel pump 25, thereby causing low-pressure fuel pump 22 to supply fuel to injector 29 via low-pressure fuel supply pipe 24. Then, when it is determined that the fuel pressure sensor has failed or the detected value is abnormal, the drive current setting unit 507 gradually reduces the drive current to be output to the injector 29 next from the provisional drive current to the set value at the time of determination of the sensor failure, etc., which is the drive current corresponding to the fuel pressure of the fuel supplied to the injector 29 by the low-pressure fuel pump 22.

On the other hand, if the fail-safe processing unit 508 determines in process P102 that the drive current is equal to or less than the set value at the time of determining the fuel pressure sensor malfunction (NO), it executes process P103 to maintain the drive current, thereby preventing the drive current output from the ECU 5 to the injector 29 from becoming smaller than necessary and preventing the injector 29 from failing to open.

The operation of the ECU 5 of this embodiment will be described below in comparison with a conventional device.

As described above, the ECU 5 of this embodiment is an electronic control device that controls the engine system ES, which includes the injectors 29 that inject fuel into the combustion chambers 31 of the engine 3 and the fuel pressure sensors 28 that detect the pressure of the fuel supplied to the injectors 29. As shown in FIG. 5 , the ECU 5 has a target fuel pressure calculation unit 501, a fuel pressure acquisition unit 502, a fault detection unit 503, a fault determination unit 504, an abnormality detection unit 505, an abnormality determination unit 506, and a drive current setting unit 507. The target fuel pressure calculation unit 501 calculates a target fuel pressure FPt of the fuel supplied to the injectors 29. The fuel pressure acquisition unit 502 acquires the fuel pressure detection value FPs of the fuel pressure sensor 28. The fault detection unit 503 detects a fuel pressure sensor failure, which is a failure of the fuel pressure sensor 28, based on the fuel pressure detection value FPs. A failure determination unit 504 determines a fuel pressure sensor failure when the detection of a fuel pressure sensor failure continues beyond a first period TP1. An abnormality detection unit 505 detects a detected value abnormality, where the difference between the target fuel pressure FPt and the detected fuel pressure value FPs and the amount of change per unit time in the detected fuel pressure value FPs exceed threshold values. An abnormality determination unit 506 determines a detected value abnormality when the detection of the detected value abnormality continues beyond a second period TP2. A drive current setting unit 507 sets a drive current for the injector 29 based on the detected fuel pressure value FPs until the fuel pressure sensor failure or detected value abnormality is detected. Then, during the period from the detection of the fuel pressure sensor failure or detected value abnormality until the detection, the drive current setting unit 507 sets a provisional drive current based on the detected fuel pressure value FPs before the fuel pressure sensor failure or detected value abnormality was detected.

6, even if the fuel pressure sensor 28 malfunctions or has an abnormality in its detection value, causing the fuel pressure detection value FPs by the fuel pressure sensor 28 to deviate from the actual fuel pressure FPr, the above-described configuration prevents a subsequent decrease in the drive current output to the injector 29. Therefore, according to the ECU 5 of this embodiment, when the fuel pressure sensor 28, which detects the fuel pressure of the fuel supplied to the injector 29, malfunctions or has an abnormality in its detection value, the injector 29 can be prevented from opening improperly, thereby preventing the engine 3 from stopping or decreasing in rotation speed.

Furthermore, in the electronic control unit 5 of this embodiment, the drive current setting unit 507 gradually reduces the drive current from the provisional drive current when it is determined that the fuel pressure sensor is malfunctioning or that the detected value is abnormal.

With this configuration, after time t2 when the fuel pressure sensor malfunction or an abnormality in the detected value is confirmed, the drive current output to the injector 29 can be gradually reduced to, for example, a predetermined set value at the time when the fuel pressure sensor malfunction or an abnormality in the detected value is confirmed, as shown by the solid line in the second chart from the bottom in Figure 6. Therefore, according to the ECU 5 of this embodiment, it is possible to reduce the shock when the injector 29 is opened and closed and improve the durability of the injector 29, compared to the conventional device shown by the dashed line in Figure 6, in which the injector drive current is set to a relatively large value, such as the maximum drive current, after the fuel pressure sensor malfunction is confirmed.

The engine system ES controlled by the electronic control unit 5 of this embodiment includes a high-pressure fuel pump 25 that supplies fuel to the injectors 29 and a low-pressure fuel pump 22 that supplies fuel from the fuel tank 21 to the high-pressure fuel pump 25. The ECU 5 also has a high-pressure fuel pump control unit 509 that controls the amount of fuel discharged by the high-pressure fuel pump 25 based on the target fuel pressure FPt. When a fuel pressure sensor malfunction or an abnormal detection value is determined, the high-pressure fuel pump control unit 509 stops the high-pressure fuel pump 25 from pressurizing and discharging the fuel, thereby causing the low-pressure fuel pump 22 to supply the fuel to the injectors 29 via the low-pressure fuel supply pipe 24. When a fuel pressure sensor malfunction or an abnormal detection value is determined, the drive current setting unit 507 gradually reduces the drive current of the injectors 29 from a provisional drive current to a drive current corresponding to the fuel pressure of the fuel supplied to the injectors 29 by the low-pressure fuel pump 22.

With this configuration, as shown by the solid line in the second chart from the bottom in Figure 6, after time t2 when it is determined that the fuel pressure sensor has failed or its detection value is abnormal, the drive current output to the injector 29 can be gradually reduced in accordance with the pressure of the fuel supplied to the injector 29 by the low-pressure fuel pump 22. Therefore, according to the ECU 5 of this embodiment, it is possible to more reliably reduce the shock that occurs when the injector 29 is opened and closed, and to more reliably improve the durability of the injector 29, compared to the conventional device shown by the dashed line in Figure 6, in which the injector drive current is set to a relatively large value, such as the maximum drive current, after it is determined that the fuel pressure sensor has failed.

As described above, according to this embodiment, it is possible to provide an electronic control device 5 that can prevent the injector 29 from failing to open properly when an abnormality occurs in the injector 29 that detects the pressure of the fuel supplied to the injector 29, thereby preventing the engine 3 from stopping or the rotation speed from decreasing, and improving the durability of the injector 29.

In contrast, in the conventional system, when a fuel pressure sensor malfunction is detected, the injector drive current is set to the maximum drive current regardless of time, as shown by the dashed line in the time chart of Figure 6. As a result, in the conventional system, the shock generated when the injector is opened and closed increases, reducing the durability of the injector. Furthermore, in the conventional system, the injector operation before the fuel pressure sensor malfunction is confirmed cannot respond to the actual fuel pressure.

The electronic control device according to the present disclosure is not limited to the ECU 5 according to the above-described embodiment. Hereinafter, several modified examples of the ECU 5 will be described with reference to Figs. 10 to 20 .

Fig. 10 is a flow chart showing a first modification of the process P08 when a failure or the like is detected in Fig. 7. In this modification, the ECU 5 executes processes P084, P085, and P086 instead of process P083 shown in Fig. 7. In process P084, while the ECU 5 is making a definitive determination of the fuel pressure sensor failure or abnormality in the detected value, the ECU 5 determines whether the fuel pressure detected value FPs of the fuel pressure sensor 28 is greater than the fuel pressure detected value FPs before the fuel pressure sensor failure or abnormality was detected.

In step P084, the drive current setting unit 507 compares the most recent fuel pressure detection value FPs obtained after the fuel pressure sensor malfunction or abnormality was detected with the previous fuel pressure detection value FPs obtained a third period prior to the time t1 at which the fuel pressure sensor malfunction or abnormality was detected. The third period may be equal to the execution cycle of the process flow shown in FIG. 5 by the ECU 5, or an integral multiple of the execution cycle of the process flow shown in FIG. 5.

If the drive current setting unit 507 determines in step P084 that the previous fuel pressure detection value FPs before the fuel pressure sensor malfunction or the like is equal to or greater than the most recent fuel pressure detection value FPs after the fuel pressure sensor malfunction or the like is detected (NO), the drive current setting unit 507 executes step P085. In step P085, the drive current setting unit 507 sets the drive current calculated by the drive current calculation unit 510 based on the previous fuel pressure detection value FPs before the fuel pressure sensor malfunction or the like is detected as the provisional drive current to be output to the injector 29, and then ends step P08 shown in FIG.

On the other hand, if the drive current setting unit 507 determines in process P084 that the most recent fuel pressure detection value FPs after the fuel pressure sensor malfunction or the like is detected is greater than the previous fuel pressure detection value FPs before the fuel pressure sensor malfunction or the like is detected (YES), the drive current setting unit 507 executes the next process P086. In this process P086, the drive current setting unit 507 sets the drive current calculated by the drive current calculation unit 510 based on the most recent fuel pressure detection value FPs after the fuel pressure sensor malfunction or the like is detected as the provisional drive current to be output to the injector 29, and then ends process P08 shown in FIG.

10, the drive current setting unit 507 sets the provisional drive current to the drive current calculated based on the most recent fuel pressure detection value FPs or the fuel pressure detection value FPs obtained three periods prior to the detection of the fuel pressure sensor failure or abnormal detection value. With this configuration, the ECU 5 of this modification can achieve the same effects as the ECU 5 of the above-described embodiment, and can more reliably prevent the injector 29 from failing to open, thereby more reliably preventing the engine 3 from stalling or decreasing in rotation speed.

FIG. 11 is a flowchart showing a second modification of the process P08 shown in FIG. 7 when a malfunction or other abnormality is detected. In this modification, the ECU 5 executes processes P087a, P087b, P088, P089a, and P089b instead of process P083 shown in FIG. 7. In process P087a, the drive current calculation unit 510 calculates a first drive current for the injector 29 from the fuel pressure detection value FPs of the fuel pressure sensor 28 immediately after the detection of the fuel pressure sensor malfunction or abnormal detection value. In process P87b, the drive current calculation unit 510 calculates a second drive current for the injector 29 from the fuel pressure detection value FPs of the fuel pressure sensor 28 at a time three periods prior to the detection of the fuel pressure sensor malfunction or abnormal detection value.

Thereafter, the drive current setting unit 507 executes a process P088 in which it determines whether the first drive current calculated by the drive current calculation unit 510 is greater than the second drive current. If the drive current setting unit 507 determines in this process P088 that the first drive current is greater than the second drive current (YES), it executes a process P089a in which it sets the first drive current as the provisional drive current to be output to the injector 29, and then ends the process P08 shown in Fig. 11. On the other hand, if the drive current setting unit 507 determines in process P088 that the second drive current is greater than the first drive current (NO), it executes a process P089b in which it sets the second drive current as the provisional drive current to be output to the injector 29, and then ends the process P08 shown in Fig. 11.

As described above, in the electronic control unit 5 according to the modified example shown in Fig. 11, the drive current setting unit 507 sets the provisional drive current to the greater of the drive current calculated based on the fuel pressure detection value FPs at a time point three periods prior to the time point at which the fuel pressure sensor malfunction or abnormal detection value was detected, and the drive current calculated based on the most recent fuel pressure detection value FPs. This modified ECU 5 can also achieve the same effects as the modified ECU 5 shown in Fig. 10.

Fig. 12 is a functional block diagram showing a first modified example of the ECU 5 shown in Fig. 4. In addition to the components shown in Fig. 4, the ECU 5 of this modified example includes, for example, a fuel injection amount calculation unit 512, a fuel injection amount determination unit 513, an intake air amount acquisition unit 514, an intake air amount determination unit 515, an engine rotation speed acquisition unit 516, an engine rotation speed determination unit 517, and a drive current correction unit 518 shown in Fig. 12.

Fig. 13 is a flowchart illustrating the operation of ECU 5 of Modification 1 shown in Fig. 12. Processes P08A to P08G shown in Fig. 13 are executed, for example, after the drive current setting unit 507 sets a provisional drive current in process P085 or P086 of the failure detection process P08 shown in Fig. 10. In process P08A shown in Fig. 13, the fuel injection amount calculation unit 512 calculates a total fuel injection amount to be injected from the injector 29 and a target fuel injection amount, which is the injection amount for each of the multiple fuel injections performed during one cycle, based on signals input from various sensors of the engine system ES, for example.

Next, in process P08B, the fuel injection amount determination unit 513 determines whether the amount of change in the total fuel injection amount is within a predetermined range, for example, based on the time-series data of the total fuel injection amount, and terminates process P08 if it determines that the amount of change is outside the predetermined range (NO). On the other hand, in process P08B, if the fuel injection amount determination unit 513 determines that the amount of change in the total fuel injection amount is within the predetermined range (YES), the intake air amount acquisition unit 514 executes process P08C to acquire time-series data of the intake air amount of the engine 3 based on the signal input from the intake sensor 11, for example.

Next, in process P08D, intake air amount determination unit 515 determines whether the amount of change in intake air amount is within a predetermined range, and if it determines that it is outside the predetermined range (NO), process P08 is terminated. On the other hand, if intake air amount determination unit 515 determines that it is within the predetermined range (YES) in process P08D, engine speed acquisition unit 516 executes process P08E to acquire the speed of engine 3 based on a signal input from crank angle sensor 37, for example.

Next, in process P08F, the engine speed determination unit 517 determines whether the acquired state in which the engine speed of the engine 3 is lower than the threshold value has continued for more than a predetermined time. If the engine speed determination unit 517 determines that the engine speed of the engine 3 is equal to or higher than a predetermined value or that the state in which the engine speed of the engine 3 has been lower than the predetermined value has continued for less than the predetermined time (NO), the engine speed determination unit 517 ends process P08.

On the other hand, if the engine speed determination unit 517 determines in process P08F that the state in which the speed of the engine 3 has decreased below the predetermined value has continued for more than the predetermined time (YES), the ECU 5 executes the next process P08G. In process P08G, the drive current correction unit 518 corrects the provisional drive current output to the injector 29 so as to increase it when a fuel pressure sensor failure or an abnormality in the detected value is confirmed, and the drive current setting unit 507 sets the provisional drive current corrected by the drive current correction unit 518 as a new provisional drive current.

Fig. 14 is a timing chart for explaining the operation of the ECU 5 of the first modified example shown in Fig. 12. The timing chart of Fig. 14 includes charts of the intake air amount and the fuel injection amount in addition to the items in the timing chart of Fig. 6.

As described above, the electronic control unit 5 of this modified example includes a fuel injection amount calculation unit 512, an intake air amount acquisition unit 514, an engine rotation speed acquisition unit 516, and a drive current correction unit 518. The fuel injection amount calculation unit 512 calculates the total fuel injection amount of the injector 29. The intake air amount acquisition unit 514 acquires the intake air amount of the engine 3 when the amount of change in the total fuel injection amount is within a predetermined range. The engine rotation speed acquisition unit 516 acquires the rotation speed of the engine 3. The drive current correction unit 518 corrects the provisional drive current so as to increase it when the rotation speed of the engine 3 is lower than a threshold value. The drive current setting unit 507 sets the provisional drive current after correction by the drive current correction unit 518 as a new provisional drive current.

14, when the rotation speed of the engine 3 drops below the threshold value and this state continues for a predetermined time while the intake air amount and fuel injection amount do not change, the provisional drive current is corrected to increase by the drive current correction unit 518. As a result, the drive current of the injector set by the drive current correction unit 518 increases, thereby preventing the engine 3 from stopping or the rotation speed from decreasing.

Fig. 15 is a functional block diagram showing a second modification of the ECU 5 shown in Fig. 4. Fig. 16 is a flowchart illustrating the operation of the ECU 5 of the second modification shown in Fig. 15. Processes P08H to P08J shown in Fig. 16 are executed, for example, after drive current setting unit 507 sets the provisional drive current to the drive current of the injector during the period from detection of a fuel pressure sensor failure or an abnormal detected value to confirmation of the fuel pressure sensor failure or abnormal detected value in process P085 or P086 of the failure detection process P08 shown in Fig. 10.

In addition to the components shown in Fig. 4 , the electronic control device 5 of the second modification includes, for example, a valve-closed state detection unit 521, a valve-closed time calculation unit 522, and a drive current correction unit 523 shown in Fig. 15 . In process P08H shown in Fig. 16 , the valve-closed state detection unit 521 detects the valve-closed state of the injector 29 and outputs the result to the valve-closed time calculation unit 522. The valve-closed state detection unit 521 detects the valve-closed state of the injector 29, for example, based on a signal output from the injector 29 when the injector 29 is closed. The valve-closed time calculation unit 522 calculates a valve-closed time observation value of the injector 29 based on the valve-closed state of the injector 29 input from the valve-closed state detection unit 521. Note that when calculating the valve-closed state observation value, the valve-opening time, which is exclusive of the valve-closed time observation value, is also obvious, and therefore the valve-opening time observation value can be calculated in the same manner as the valve-closed time observation value.

Next, in process P08I, the drive current correction unit 523 determines whether the valve-closed time observation value calculated by the valve-closed time calculation unit 522 is longer than a predetermined valve-closed time (described later), and if it determines that the valve-closed time observation value is shorter than the predetermined valve-closed time (NO), it ends process P08 shown in Fig. 10. On the other hand, in process P08I, if the drive current correction unit 523 determines that the valve-closed time observation value calculated by the valve-closed time calculation unit 522 is longer than the predetermined time (YES), it corrects the provisional drive current set in process P085 or P086 of the failure or other detection process P08 shown in Fig. 10 so as to increase it.

The process in step P08I can also be performed based on the valve-opening time observation value. In this case, for example, drive current correction unit 523 determines whether the valve-opening time observation value calculated by valve-closing time calculation unit 522 is longer than a predetermined valve-opening time. If the drive current correction unit 523 determines that the valve-opening time observation value is longer than the predetermined valve-opening time (NO), the process in step P08 shown in FIG. 10 ends. On the other hand, if the drive current correction unit 523 determines that the valve-opening time observation value calculated by valve- closing time calculation unit 522 is shorter than the predetermined valve-opening time (YES) in step P08I, the drive current correction unit 523 corrects the provisional drive current set in step P085 or P086 of the failure detection process P08 shown in FIG. 10 so as to increase it. The predetermined valve-closing time and the predetermined valve-opening time can be set based on, for example, the total fuel injection amount injected from injector 29 or a target fuel injection amount, which is the injection amount for each of multiple fuel injections performed during one combustion cycle of engine 3.

Fig. 17 is a timing chart illustrating the operation of the ECU 5 of the second modified example shown in Fig. 15. The timing chart of Fig. 17 includes a chart of valve closing time in addition to the items in the timing chart of Fig. 14. The dashed line in the chart of the fuel injection amount in Fig. 14 represents the target fuel injection amount.

As described above, the electronic control unit 5 of this modified example has a valve-closed state detection unit 521, a valve-closed time calculation unit 522, and a drive current correction unit 523. The valve-closed state detection unit 521 detects the closed state of the injector 29. The valve-closed time calculation unit 522 calculates the valve-closed time or the valve-open time of the injector 29 based on the detection result of the valve-closed state. The drive current correction unit 523 increases the provisional drive current when the valve-closed time of the injector 29 is longer than a predetermined valve-closed time or when the valve-open time of the injector 29 is shorter than the predetermined valve-open time.

With this configuration, the ECU 5 of the second modified example can detect a decrease in the actual fuel injection amount (observed valve open time) of the injector 29 using the valve closing detection function of the injector 29. That is, as shown in Figure 17, when the observed valve closing time of the injector 29 is longer than a predetermined valve closing time or when the observed valve opening time of the injector 29 is shorter than a predetermined valve open time, the ECU 5 can detect a decrease in the actual fuel injection amount of the injector 29 and increase the provisional drive current output to the injector 29. As a result, the decrease in the fuel injection amount is resolved, and it is possible to prevent the engine 3 from stopping or decreasing in rotation speed.

Fig. 18 is a functional block diagram showing a third modification of the ECU 5 shown in Fig. 4. Fig. 19 is a flowchart illustrating the operation of the third modification of the ECU 5 shown in Fig. 18. Processes P08K to P08O shown in Fig. 19 are performed, for example, after a provisional drive current is set by drive current setting unit 507 in process P085 or P086 of the failure detection process P08 shown in Fig. 10 during the period from the detection of a fuel pressure sensor failure or an abnormal detected value to the determination of the fuel pressure sensor failure or the abnormal detected value.

4, the ECU 5 of the third modification includes, for example, an intake air amount obtaining unit 531, an intake air amount determining unit 532, a fuel injection amount calculating unit 533, a fuel injection amount determining unit 534, and a drive current correcting unit 535, all of which are shown in Fig. 18. In process P08K shown in Fig. 19, the intake air amount obtaining unit 531 calculates and obtains the intake air amount based on a signal input from the intake sensor 11, for example.

Next, in process P08L, intake air amount determination unit 532 determines whether the amount of change in intake air amount is within a predetermined range, for example, based on time-series data of the intake air amount, and ends process P08 if it determines that it is outside the predetermined range (NO). On the other hand, in process P08L, if intake air amount determination unit 532 determines that it is within the predetermined range (YES), fuel injection amount calculation unit 533 executes process P08M to calculate the total fuel injection amount to be injected from injector 29, for example, based on signals input from various sensors of engine system ES.

Next, in process P08N, fuel injection amount determination unit 534 determines whether the amount of change in the total fuel injection amount is within a predetermined range, for example, based on the time-series data of the fuel injection amount, and ends process P08 if it is determined to be within the predetermined range (NO). On the other hand, if it is determined to be outside the predetermined range (NO) in process P08N, ECU 5 executes the next process P08O. In process P08O, drive current correction unit 535 corrects the provisional drive current output to injector 29 so as to increase it, and drive current setting unit 507 sets the provisional drive current corrected by drive current correction unit 535 as a new provisional drive current.

Fig. 20 is a timing chart for explaining the operation of the ECU 5 of the third modified example shown in Fig. 18. In the timing chart of Fig. 20, a chart of the intake air amount and the fuel injection amount is added instead of the chart of the engine speed shown in Fig. 6.

As described above, the electronic control unit 5 of the third modified example includes an intake air amount obtaining unit 531, a fuel injection amount calculating unit 533, and a drive current correcting unit 535. The intake air amount obtaining unit 531 obtains the intake air amount of the engine 3. The fuel injection amount calculating unit 533 calculates the fuel injection amount of the injector 29 when the amount of change in the intake air amount is within a predetermined range. The drive current correcting unit 535 corrects the provisional drive current so as to increase it when the total fuel injection amount has decreased.

For example, if the total fuel injection amount suddenly decreases, the amount of fuel discharged from the high-pressure fuel pump 25 to the injectors 29 may exceed the amount of fuel injected from the injectors 29 into the combustion chambers, causing a sudden increase in fuel pressure in the common rail 27. However, if a malfunction of the fuel pressure sensor 28 or an abnormal detection value is detected, this increase in fuel pressure cannot be detected. However, according to the configuration of the third modification, as shown in Figure 20, if it is detected that the amount of change in the fuel injection amount is outside the predetermined range, the provisional drive current output to the injectors 29 can be increased. As a result, the engine 3 is prevented from stalling or the rotation speed from decreasing due to an increase in fuel pressure.

Above, we have described in detail the embodiments and variations of the electronic control device according to the present disclosure using the drawings, but the specific configuration is not limited to these embodiments and variations, and even if there are design changes, etc., within the scope that does not deviate from the gist of the present disclosure, they are included in the present disclosure.

21 Fuel tank 22 Low-pressure fuel pump 24 Low-pressure fuel supply passage (low-pressure fuel supply pipe)
25 High-pressure fuel pump 28 Fuel pressure sensor 29 Injector 3 Engine 31 Combustion chamber 5 ECU (Electronic Control Unit)
501 Target fuel pressure calculation unit 502 Fuel pressure acquisition unit 503 Failure detection unit 504 Failure determination unit 505 Abnormality detection unit 506 Abnormality determination unit 507 Drive current setting unit 509 High-pressure fuel pump control unit 512 Fuel injection amount calculation unit 514 Intake air amount acquisition unit 516 Engine rotation speed acquisition unit 518 Drive current correction unit 521 Valve closed state detection unit 522 Valve closed time calculation unit 523 Drive current correction unit 531 Intake air amount acquisition unit 533 Fuel injection amount calculation unit 535 Drive current correction unit ES Engine system FPs Fuel pressure detection value FPt Target fuel pressure TP1 First period TP2 Second period

Claims (9)

An electronic control device for controlling an engine system including an injector that injects fuel into a combustion chamber of an engine and a fuel pressure sensor that detects the pressure of the fuel supplied to the injector,
a target fuel pressure calculation unit that calculates a target fuel pressure of the fuel to be supplied to the injector;
a fuel pressure acquisition unit that acquires a fuel pressure detection value of the fuel pressure sensor;
a failure detection unit that detects a failure of the fuel pressure sensor based on the detected fuel pressure value;
a failure determination unit that determines a failure of the fuel pressure sensor when the detection of the failure of the fuel pressure sensor continues beyond a first period;
an abnormality detection unit that detects an abnormality in the detected fuel pressure value based on a difference between the target fuel pressure and the detected fuel pressure value and an amount of change in the detected fuel pressure value per unit time;
an abnormality determination unit that determines the abnormality of the detected fuel pressure value when the abnormality of the detected fuel pressure value continues beyond a second period;
a drive current setting unit that sets a drive current for the injector in accordance with the fuel pressure of the fuel,
the drive current setting unit sets, as the drive current for the injector, a provisional drive current corresponding to the fuel pressure detection value at a time before the fuel pressure sensor failure or the detection of the abnormal detection value is detected, during a period from the detection of the fuel pressure sensor failure or the detection of the abnormal detection value to the confirmation of the fuel pressure sensor failure or the confirmation of the abnormal detection value. The electronic control device described in claim 1, characterized in that the drive current setting unit gradually reduces the drive current of the injector from the provisional drive current when the fuel pressure sensor failure or the detected value abnormality is confirmed. the engine system includes a high-pressure fuel pump that draws in the fuel and discharges it under pressure to the injector, a low-pressure fuel supply passage that bypasses and connects an intake side and a discharge side of the high-pressure fuel pump, and a low-pressure fuel pump that supplies the fuel from a fuel tank to the low-pressure fuel supply passage and the intake side of the high-pressure fuel pump,
the electronic control device has a high-pressure fuel pump control unit that, when a failure of the fuel pressure sensor or an abnormality in the detected value is confirmed, stops pressurizing and discharging the fuel by the high-pressure fuel pump, thereby causing the low-pressure fuel pump to supply the fuel to the injector through the low-pressure fuel supply passage,
3. The electronic control device according to claim 2, wherein, when the fuel pressure sensor malfunctions or the detected value is abnormal, the drive current setting unit gradually reduces the drive current of the injector from the provisional drive current to a predetermined set value corresponding to the fuel pressure value of the fuel supplied to the injector by the low-pressure fuel pump. The electronic control device described in claim 1, characterized in that the provisional drive current is set based on the higher of the most recent fuel pressure detection value and the fuel pressure detection value at a time point three periods prior to the time point at which the fuel pressure sensor failure or the abnormal detection value was detected. The electronic control device described in claim 1, characterized in that the drive current setting unit sets the interim drive current to the larger of the drive current of the injector calculated based on the fuel pressure detection value at a time point going back a third period from the time point when the fuel pressure sensor failure or the abnormal detection value was detected, and the drive current of the injector calculated based on the most recent fuel pressure detection value. a fuel injection amount calculation unit that calculates a fuel injection amount of the injector;
an intake air amount obtaining unit that obtains an intake air amount of the engine when a change amount of the fuel injection amount is within a predetermined range;
an engine rotation speed acquisition unit that acquires the rotation speed of the engine;
2. The electronic control device according to claim 1, further comprising a provisional drive current correction unit that corrects the provisional drive current to increase it when the engine speed is deemed to be lower than a predetermined speed during the period from the detection of a failure of the fuel pressure sensor or the abnormality in the detected value to the confirmation of the fuel pressure sensor failure or the abnormality in the detected value. a target fuel injection amount calculation unit that calculates a total fuel injection amount of the injector in accordance with an intake air amount of the engine; and a valve opening duration calculation unit that determines a valve opening duration for opening the fuel injection valve in accordance with the total fuel injection amount;
a valve-closed state detection unit that detects a valve-closed state of the injector;
a valve closing time calculation unit that calculates a valve closing time observation value or a valve opening time observation value of the injector based on a valve closing state of the injector, and sets a predetermined valve closing time or a predetermined valve opening time in accordance with the valve opening time length,
2. The electronic control device according to claim 1, further comprising a drive current correction unit that corrects the provisional drive current so as to increase it when an observed value of a valve closing time of the injector is longer than the predetermined valve closing time or when an observed value of a valve opening time of the injector is shorter than the predetermined valve opening time. an intake air amount acquisition unit that acquires an intake air amount of the engine;
a fuel injection amount calculation unit that calculates a total fuel injection amount of the injector based on the intake air amount;
2. The electronic control device according to claim 1, further comprising a drive current correction unit that corrects the provisional drive current so as to increase it if the total fuel injection amount is lower than a predetermined value during the period from the detection of a failure of the fuel pressure sensor or the abnormality in the detected value to the confirmation of the failure of the fuel pressure sensor or the confirmation of the abnormality in the detected value. The electronic control device described in claim 8, characterized in that the drive current correction unit corrects the provisional drive current based on the amount of change per unit time in the total fuel injection amount during the period from the detection of a fuel pressure sensor failure or an abnormal detection value to the confirmation of the fuel pressure sensor failure or the confirmation of the abnormal detection value.