JP2002332906A - Control device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily make a change for a cylinder discriminating process in starting in accordance with characteristics of an automobile or an engine in a control device for an internal combustion engine. SOLUTION: A cylinder discriminating IC detects a specified rotation position of a shaft crank based on a crank angle signal, and separately from the cylinder discriminating IC, detection of the specified rotation position of the crankshaft is conducted based on the crank angle signal in a process of S120. When the process of S120 is executed, a CPU conducts cylinder discrimination of the internal combustion engine based on result of detection by this process. When the process of S120 is not executed, it conducts cylinder discrimination of the internal combustion engine based on result of detection by the cylinder discriminating IC. When a rotation speed of the shaft crank is large than a prescribed rotation speed, the process of cylinder discrimination is prohibited.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control apparatus for an internal combustion engine that detects a rotational position of a crankshaft to determine a cylinder.

[0002]

2. Description of the Related Art A crank angle signal Ne output from a crank angle sensor and a G signal output from a cam angle sensor are input to an engine control device for controlling an internal combustion engine (engine) for cylinder identification. .

A crank angle sensor includes, for example, a rotor fixed to a crankshaft of an engine, and a
And a pickup coil for detecting passage of a tooth formed at an interval of ° CA. Basically, the crank angle sensor outputs a pulse-like crank angle signal Ne every time the crankshaft rotates by 10 ° C., but a missing tooth portion with two missing teeth is provided on the outer periphery of the rotor. Therefore, when the missing tooth portion comes to a position facing the pickup coil (that is, when the rotational position of the crankshaft comes to the specific rotational position), the pulse interval is tripled (that is, 30 times). ° C A). For example, as described in Japanese Patent Application Laid-Open No. 8-271284, when a missing tooth portion is provided at one position, a period in which the pulse interval becomes longer occurs every 360 ° CA.

A cam angle sensor detects the passage of a rotor fixed to a camshaft of an engine which rotates at a ratio of 1/2 to the rotation of a crankshaft, and the passage of teeth formed at, for example, one place on the outer periphery of the rotor. And a pickup coil to be detected. In this case, the cam angle sensor outputs a pulsed G signal each time the camshaft rotor makes one revolution (ie, every 720 ° C.).

In order to discriminate the cylinder from these signals, it is necessary to perform signal processing at every 10 ° C. synchronized with the crank angle signal Ne. , The processing load of the program increases, which may affect control performance. Therefore, signal processing synchronized with the crank angle signal is conventionally performed by a hardware circuit (IC). I have.

[0006]

In recent years, it has been required to improve the startability of the engine due to regulations and the like, and it is necessary to detect the rotational position of the crankshaft as soon as possible when starting the engine to determine the cylinder. It has become.
For that purpose, it is necessary to develop a method of detecting the rotational position at the start according to the characteristics of the car or engine (number of cylinders, displacement, etc.), and to flexibly respond to such differences between cars and engines , It is desirable to be realized by software for detecting the rotational position. However, if this is attempted to be realized by software, the processing load may increase when the engine rotates at a high speed.

[0007] The present invention is against such a background,
It is an object of the present invention to provide a control device for an internal combustion engine, in which a cylinder discriminating process at the time of starting can be easily changed according to characteristics of an automobile or an engine.

[0008]

Means for Solving the Problems and Effects of the Invention In order to solve the above problems, in a control device for an internal combustion engine according to the present invention (claim 1), a signal processing circuit (hardware circuit) converts a crank angle signal to a crank angle signal. The specific rotation position of the crankshaft is detected based on this, and separately from this signal processing circuit,
The specific rotation position detecting means also detects the specific rotation position of the crankshaft based on the crank angle signal. This specific rotational position detecting means is a functional means realized by the CPU operating based on a program.

When the specific rotational position detecting means is operating, the control means determines the cylinder of the internal combustion engine based on the detection result by the specific rotational position detecting means, while the specific rotational position detecting means is operating. If not, the cylinder of the internal combustion engine is determined based on the detection result by the signal processing circuit. Then, the first prohibiting means compares the rotation speed of the crankshaft with the first reference rotation speed, and as a result of the comparison, when the rotation speed of the crankshaft is larger than the first reference rotation speed, Operation is prohibited.

That is, according to the control device of the present invention (claim 1), at the time of starting (including the time of restarting from the engine stalled state) when the engine shifts from the stopped state to the operating state, the crank speed (crank) is reduced. Only until the rotation speed of the shaft exceeds the first reference rotation speed, the specific rotation position of the crankshaft is detected by processing by software.

Therefore, in order to improve the startability of the engine, the cylinder discriminating process at the time of starting can be easily changed according to the characteristics of the vehicle or the engine by changing the program. In addition, when the crank rotation speed becomes higher than the first reference rotation speed, the detection processing of the specific rotation position by the program is prohibited, and the detection result by the hardware circuit is used. There is no hanging.

The specific rotational position of the crankshaft should be detected at a predetermined interval (for example, 360 ° C.), but the specific rotational position may be detected at a different interval. In this case, the detection by the specific rotational position detecting means is not performed normally. Therefore, in the control device for an internal combustion engine according to claim 2, the control means determines whether the detection interval of the specific rotation position of the crankshaft by the specific rotation position detection means is normal or abnormal. It is configured to stop the cylinder discrimination based on the detection result by the rotational position detecting means.

According to the control device having the above-described configuration, since the cylinder discrimination based on the erroneous detection result of the specific rotation position is not performed, it is possible to perform the accurate cylinder discrimination. Becomes Further, since the signal level (amplitude) of the crank angle signal decreases as the rotation speed of the crankshaft decreases, the detection accuracy of the crank angle signal decreases when the rotation speed of the crankshaft is low, and the rotation position of the crankshaft decreases. Actually, even if the position is not the specific rotational position, the possibility of erroneously detecting that the position is the specific rotational position tends to increase.

Therefore, in the control device for the internal combustion engine according to the third aspect, the second inhibiting means compares the rotation speed of the crankshaft with the second reference rotation speed, and as a result of the comparison, the rotation of the crankshaft is determined. When the number is smaller than the second reference rotation number, the operation of the specific rotation position detection means is prohibited. According to the control device of the third aspect, the specific rotation position is detected after the rotation speed of the crankshaft becomes higher than the second reference rotation speed and the signal level of the crank angle signal becomes sufficiently high. Is performed, the possibility of erroneous detection is reduced, and unnecessary starting of the processing according to the program can be omitted to reduce the processing load on the CPU.

If the voltage of the power supply for supplying electric power to the control device is low, the signal level of the crank angle signal is reduced. Must be higher. Therefore, in the control device for the internal combustion engine according to claim 4, the rotation speed setting means detects the voltage of the power supply for supplying power to the control device, and sets the second reference rotation speed in accordance with the detected voltage. It is configured to be set. According to the control apparatus for an internal combustion engine according to the fourth aspect, when the power supply voltage is low enough to affect the detection of the specific rotational position, the second reference rotational speed is set to be high. Therefore, the possibility of erroneous detection of the specific rotational position can be reduced.

[0016]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1A is a diagram illustrating a configuration of a control device 20 (hereinafter, simply referred to as “ECU”) of an internal combustion engine as one embodiment. The ECU 20 controls a four-cylinder, four-cycle engine. As shown in FIG. 1, the ECU 20 includes a cylinder discrimination IC 21 and a CPU 22 (microcomputer) that performs various processes (such as an ignition control process and a fuel injection control process) for controlling the engine.

The cylinder discriminating IC 21 receives the crank angle signal Ne output from the crank angle sensor 30 and the G signal output from the cam angle sensor 31. The crank angle sensor 30 includes a rotor 30a fixed to the crankshaft of the engine, and a pickup coil 30 for detecting passage of teeth formed at intervals of 10 ° on the outer periphery of the rotor 30a.
b. Since the rotor 30a is provided with a missing tooth portion with two missing teeth on the outer periphery, the crank angle signal Ne
Is generated in pulses each time the crankshaft rotates 10 ° (every 10 ° C.), and the rotational position of the crankshaft is changed to a specific rotational position (ie, the toothless portion of the rotor 30a faces the pickup coil 30b). Angle), the pulse interval is tripled (ie, 30 ° C.). Then, portions where the pulse interval becomes long (that is, the pulse signal is lost twice) occur at intervals of 360 ° C.

The cam angle sensor 31 includes a rotor 31a fixed to a camshaft of an engine which rotates at a ratio of 1/2 with respect to the rotation of the crankshaft, and one of the outer circumferences of the rotor 31a.
And a pickup coil 31b for detecting passage of a tooth formed at the location. The G signal is output from the crank angle sensor 30.
At a rate of one time during two rotations of the rotor 30a, and
A period (120) from when the missing tooth is detected by the pickup coil 30b until the crankshaft further rotates 120 °.
(A period of ° CA).

The cylinder discriminating IC 21 corresponds to a "signal processing circuit" in the claims, shapes the waveforms of the crank angle signals Ne and G, detects the rotational position of the crankshaft based on these signals, and performs cylinder discrimination. Signal (TDC signal, etc.)
In addition to the above, a pulse signal for each 30 ° C. (hereinafter referred to as “30 ° A signal”) and a G signal for each 720 ° C.
2 is output. The 30 ° C. A signal is a signal generated by dividing the frequency of the crank angle signal Ne.

In this embodiment, the detection of the specific rotational position of the crankshaft in the normal state (that is, the detection of the missing tooth portion) is carried out by the cylinder discriminating IC 21 as in the prior art. The control is performed by the CPU 22. When the engine is started, the CPU 22 performs processing according to software to detect the rotational position by a method suitable for the characteristics of the engine and the like.

That is, when the crank speed is equal to or lower than the predetermined speed (at the time of starting), the cylinder discriminating IC 2
Cylinder discrimination and engine control are performed using the result of the rotational position detection performed by the CPU 22 without using the result of the rotational position detection by the control unit 1 to improve the startability of the engine. Therefore, a pulse signal (hereinafter, referred to as a “10 ° C. A signal”) at every 10 ° C. for the CPU 22 to detect the rotational position when the engine is started or the like is input from the cylinder determination IC 21 to the CPU 22.

The 10 ° C. signal is a signal obtained by shaping the waveform of the crank angle signal Ne as shown in FIG.
Note that the voltage value of the vehicle-mounted battery is input to the CPU 22 from an A / D converter (not shown). Below, CPU
The processing performed by 22 will be described with reference to the flowcharts of FIGS. Note that a ROM, a RAM (not shown) and the like are connected to the CPU 22, and the CPU 22 performs processing according to a program stored in the ROM.

FIG. 2 is a flowchart showing the initialization processing. The initialization process is performed by the on-board battery (not shown)
It is started when power supply to U20 is started, and performs initial setting of output ports and the like (S10), start setting of interrupt processing (S20), and initialization of RAM (S30).
In the start setting of the interrupt processing in S20, the start of the cylinder discrimination processing (FIG. 3) using the 10 ° C. A signal as the interrupt signal is permitted.

FIG. 3 is a flowchart showing the cylinder discriminating process. This cylinder discriminating process is performed at the time of starting.
It detects the rotational position of the crankshaft, determines the cylinder, and the like. Immediately after the start of the engine, the start of the cylinder discriminating process is permitted in S20, and the cylinder discriminating process is started at the falling timing of the pulse in the 10 ° C. A signal. Whether the activation of the cylinder discrimination process is permitted or prohibited is set by a flag.

When the cylinder discriminating process is started, first, a judgment speed for determining whether or not to perform the cylinder judgment is set based on the battery voltage (S100), and the engine speed and the judgment speed are determined. A comparison is made (S110). The determination rotational speed is defined as a numerical table in a predetermined storage means so as to correspond to the battery voltage and to have a higher value as the battery voltage is lower. The determined rotation speed corresponds to the “second reference rotation speed” in the claims, the processing in S100 corresponds to “rotation speed setting means” in the claims, and the processing in S110 corresponds to the second inhibition means in the claims. Is equivalent to

If the result of determination in S110 is that the crank speed is less than the determined speed (NO), the cylinder discriminating process is temporarily terminated, but if the crank speed is greater than the determined speed (YES). Then, a missing tooth determination is performed (S12).
0). The processing in S120 corresponds to “specific rotational position detecting means” in the claims.

In the missing tooth judgment, the pulse interval is detected by monitoring the interval of the falling timing of the 10 ° A signal. Then, the ratio of the current pulse interval to the previous pulse interval is equal to or greater than a predetermined missing tooth determination value (for example, 1.
If 4 times or more), it is determined that a missing tooth has been detected. The previous pulse interval is stored in the RAM.

If it is determined by the missing tooth determination (S120) that the tooth is missing (S130: YES), it is then determined whether the gap between the missing teeth is normal (S140). In this embodiment, the missing tooth portion is to be detected once each time the crankshaft makes one rotation. However, when the rotation speed temporarily decreases slightly near TDC, the signal level of the crank angle signal Ne becomes lower. As a result, there is a possibility that a portion that is not missing a tooth is determined as a missing tooth. Therefore, by referring to a crank counter described later that indicates the rotation angle of the crankshaft, it is determined in S140 whether or not the interval between the timing when the missing tooth was previously detected and the current timing is normal.

If the gap between the missing teeth is abnormal (S14)
0: NO), the cylinder discriminating process ends once. That is,
The process of S140 is a control of "claim determining whether the detection interval of the specific rotation position of the crankshaft is normal or abnormal, and if it is abnormal, cancels the cylinder determination based on the detection result by the specific rotation position detection means" Functions as a means.

If the tooth gap is normal (S14)
0: YES), the crank counter is cleared ("$ 00" is set) (S150), and the routine goes to S190. In addition,
When a missing tooth is detected for the first time, the detection interval itself of the missing tooth part cannot be defined, so that S is regarded as normal.
The process proceeds to 150.

On the other hand, if it is not determined in S120 that there is a missing tooth (S130: NO), it is determined whether a missing tooth has already been detected (S160). In the initial setting process, the crank counter defined in the RAM has "＄ F
F "is set and the crank counter is cleared when a missing tooth is detected. Therefore, in the process of S160, it is determined whether or not the missing tooth has been detected by referring to whether or not this is" @FF ". I do.

If the missing tooth has been detected (S
160: YES), the crank counter is incremented (S170), and the process proceeds to S190. If a missing tooth has not been detected (S160: NO), "@FF" is set in the crank counter (S180), and then S
Move to 190.

In S190, it is determined whether or not the crank counter is 12 counts. That is, in S190, after the missing tooth portion is detected, the crankshaft is further moved by 120.
It is determined by a crank counter whether or not the motor has rotated by ° C. As a result of this judgment, 12
If the rotation is not 0 ° C. (S190: NO), the injection timing is not reached, and the cylinder discrimination processing ends.
On the other hand, if the motor has been rotated at 120 ° C. A after the detection of the missing tooth (S190: YES), the detection of the missing tooth is performed to determine whether the top dead center of the first cylinder or the fourth cylinder is the top dead center. 1 from time
It is determined whether the G signal has been input during the elapse of 20 ° C. (S200). In the present embodiment, the missing tooth portion is provided so as to be detected at 120 ° C. before the top dead center of the first cylinder and the fourth cylinder.
It is set so that a G signal is generated between the temperature ℃ A and the top dead center of the first cylinder.

The G signal is 120 ° C. A from the detection of the missing tooth.
If it is input during the lapse of time (S200: YE
S) Since it is known that the first cylinder is at the top dead center, fuel injection is performed on the third cylinder and the fourth cylinder in the intake stroke and the exhaust stroke, respectively (S210). On the other hand, when the G signal is not input during the elapse of 120 ° C. A from the detection of the missing tooth (S200: NO), it is known that the fourth cylinder is at the top dead center. Fuel injection is performed on the first cylinder and the second cylinder in the stroke (S220). Note that the processing of S150 to S200 is
It functions as "control means for determining the cylinder of the internal combustion engine based on the detection result by the specific rotational position detecting means".

FIG. 4 is a flowchart showing a cylinder discrimination prohibition process for prohibiting the execution of the above-described cylinder discrimination process when the start of the engine is completed. This cylinder discrimination prohibition processing is performed in synchronization with the rotation of the crankshaft (for example, 30 ° C.
Every). When the engine is started, first, a crank rotation speed is calculated from a time interval corresponding to 30 ° C. (S30).
0), it is determined whether or not the crank rotation speed is equal to or more than a predetermined rotation speed (corresponding to “a first reference rotation speed” in the claims, for example, 500 rpm) (S310).

If the crank rotation speed is not equal to or higher than the predetermined rotation speed (S310: NO), the cylinder discrimination prohibition process is immediately terminated. However, if it is determined that the crank rotation speed is equal to or higher than the predetermined rotation speed. (S310: YES), execution of the cylinder discrimination process is prohibited (S320). That is, S31
0 and the processing of S320 correspond to the "first prohibiting means" in the claims.
Functioning as

FIG. 5 shows whether the engine is stalled or not. If it is determined that the engine is stalled,
9 is a flowchart illustrating engine stall determination processing that permits execution of cylinder determination processing. This engine stall determination process is started at predetermined time intervals (for example, at every 65 ms). When activated, first, it is determined whether or not the crank rotation speed is equal to or higher than a predetermined rotation speed (S400). And
If the rotation speed is equal to or higher than the predetermined rotation speed (S400: YES), the stop counter is cleared (S410), and the process proceeds to S430. The stop counter is a variable for measuring the duration of a state in which the crank speed is equal to or less than a predetermined value. on the other hand,
If the crank speed is less than the predetermined speed (S40)
0: NO), the stop counter is incremented (S42).
0), and then proceed to S430.

In S430, it is determined whether or not an engine stall has occurred. More specifically, it is determined that the engine stall has occurred when the state in which the stop counter is equal to or more than the predetermined value, that is, the crank speed is equal to or less than the predetermined value, is maintained for a predetermined time or more. If the engine is not stalled (S430: NO), the engine stall determination process is immediately terminated. If it is determined that the engine is stalled (S430: YES), execution of the cylinder determination process is permitted (S440).

As described above, in the control device for an internal combustion engine of the present embodiment, the cylinder discriminating IC 21 outputs the crank angle signal Ne.
, The specific rotational position of the crankshaft is detected based on the crank angle signal Ne in the process of S120 separately from the cylinder discriminating IC 21 in the process of S120. Then, the CPU 22 executes S
When the processing of step 120 is operating, the cylinder of the internal combustion engine is determined based on the detection result of this processing.
When the processing in S120 is not operating, the cylinder discrimination I
The cylinder of the internal combustion engine is determined based on the detection result of C21. When the rotation speed of the crankshaft is higher than the predetermined rotation speed (S310: YES), execution of the cylinder determination process including S120 is prohibited.

Therefore, when the engine is started from the stopped state to the operating state (including when the engine is restarted from the engine stall state), the crankshaft of the crankshaft is processed by software until the crank speed exceeds a predetermined speed. The detection of the specific rotational position is performed. For this reason, in order to improve the startability of the engine, a method of detecting the rotational position of the crankshaft suitable for the features (the number of cylinders, the displacement, etc.) of the vehicle or the engine can be easily applied by changing the program. . When the crank rotation speed becomes higher than the predetermined rotation speed, the processing for detecting the specific rotation position by the program is prohibited, and the cylinder discrimination IC
Since the detection result by 21 is used, a large load is not applied to the processing of the program.

Further, the control device 20 of this embodiment is configured such that when the detection interval of the specific rotation position of the crankshaft is abnormal (S140: NO), the cylinder discriminating process is immediately terminated. Therefore, it is not necessary to perform the cylinder determination based on the erroneous detection result of the specific rotation position of the crankshaft, and thus it is possible to perform the accurate cylinder determination.

Further, the control device 20 of this embodiment compares the rotational speed of the crankshaft with the determined rotational speed. As a result of the comparison, when the rotational speed of the crankshaft is smaller than the determined rotational speed (S110: NO) ), And is configured to prohibit the missing tooth determination in S120. For this reason, the missing tooth determination is performed after the signal level of the crank angle signal Ne becomes sufficiently high, so that the possibility of erroneous detection of the missing tooth portion is reduced, and the activation of unnecessary processing is omitted by eliminating the CPU. Processing load can be reduced.

Also, the determination rotation speed is set to be higher as the battery voltage is lower (S10
0), it is possible to improve the detection accuracy of the missing tooth portion. As mentioned above, although one Example of this invention was described, this invention is not limited to the said Example, but can take various aspects.

For example, in the above embodiment, the cylinder discriminating process (FIG. 2) by software is prohibited when the crank rotation speed exceeds 500 rpm.
It can be changed appropriately according to the type of engine. Further, in the above-described embodiment, a four-cylinder engine has been described as an example. However, the present invention is not limited to this, and can be applied to a six-cylinder engine or an eight-cylinder engine.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a configuration of a control device for an internal combustion engine according to an embodiment and signals handled by the device.

FIG. 2 is a flowchart illustrating an initialization process.

FIG. 3 is a flowchart illustrating a cylinder discrimination process.

FIG. 4 is a flowchart illustrating a cylinder discrimination prohibition process.

FIG. 5 is a flowchart illustrating engine stall determination processing.

[Explanation of symbols]

 Reference Signs List 20 ... Control device 21 ... Cylinder identification IC 22 ... CPU 30 ... Crank angle sensor 31 ... Cam angle sensor

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3G084 BA00 BA03 CA01 DA04 DA05 DA27 DA30 EA07 EC02 FA36 FA38 FA39

Claims (4)

[Claims] 1. A signal processing circuit for detecting a specific rotational position of a crankshaft based on a crank angle signal generated at each predetermined rotational angle of the crankshaft according to rotation of the crankshaft of the internal combustion engine. A specific rotation position detecting means for detecting the specific rotation position separately from the signal processing circuit based on the crank angle signal according to a program for detecting a specific rotation position of the crankshaft; When the rotational position detecting means is operating, the cylinder of the internal combustion engine is determined based on the detection result by the specific rotational position detecting means. When the specific rotational position detecting means is not operating, the signal processing circuit Control means configured to perform cylinder discrimination of the internal combustion engine based on the detection result; and comparing the rotation speed of the crankshaft with a first reference rotation speed,
When the result of the comparison indicates that the rotation speed of the crankshaft is higher than the first reference rotation speed, the first rotation control device prohibits the operation of the specific rotation position detection device. Control device. 2. The control means determines whether the detection interval of the specific rotation position of the crankshaft by the specific rotation position detection means is normal or abnormal, and when the detection interval is abnormal, the detection result by the specific rotation position detection means The control apparatus for an internal combustion engine according to claim 1, wherein the cylinder discrimination based on (i) is stopped. 3. The rotational speed of the crankshaft is compared with a second reference rotational speed. As a result of the comparison, when the rotational speed of the crankshaft is smaller than the second reference rotational speed, the specific rotational position detecting means is provided. The control device for an internal combustion engine according to claim 1 or 2, further comprising a second prohibition unit that prohibits the operation of (1). 4. A rotation speed setting means for detecting a voltage of a power supply for supplying power to the control device and setting the second reference rotation speed based on the detected voltage. 3. The control device for an internal combustion engine according to claim 1.