JP2000073840A - Fuel injection control device for vehicular internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To permit a vehicular running in a state capable of fuel injection, even if there is any abnormality in a fuel injection system. SOLUTION: The drive circuit 30 for driving an injector is provided separately in addition to an ECU 20 for controlling a fuel injection. The drive circuit 30 controls the fuel injection amount by turning the injector 16 ON or OFF based on an electrification signal IJT sent from the ECU 20 and produces an abnormality diagnosis signal Diag showing whether a current is carried to the injector 16 while synchronizing with the electrification signal IJT and sends the Diag signal to the ECU 20 at each time. The ECU 20 detects the existence/ absence of a misfire at every cylinders. When the misfire is not detected, even if an abnormality diagnosis signal Diag showing a fuel injection system abnormality is outputted from the drive circuit 30, the electrification signal IJT to each cylinder is outputted continuously and the fuel injection by an injector 16 is continued, in the ECU 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection control device for a vehicle internal combustion engine.

[0002]

2. Description of the Related Art In recent years, so-called direct-injection engines for directly injecting fuel into a cylinder (combustion chamber) of an engine have become commercially available. In a direct injection engine, since the fuel pressure is higher than in a conventional port injection engine, the driving current of an injector that injects the high-pressure fuel also increases. Therefore, a drive circuit (EDU: Electric Driver Unit) separate from the electronic control unit (ECU) is provided,
In some cases, an injector energizing signal is transmitted to a driving circuit from the controller, and the driving of the injector is controlled by the driving circuit in accordance with the energizing signal.

Further, in response to a request for performing a self-diagnosis in the engine control system, it is detected whether or not a drive current has flowed through the injector in synchronization with an energization signal, and fuel injection is performed based on an abnormality diagnosis signal corresponding to the detection result. Some systems diagnose a failure of the system (injector-drive circuit system). That is, when the abnormality diagnosis signal is not generated in synchronization with the energization signal, it is determined that the fuel injection system has failed and the energization signal for all cylinders is not output.

[0004]

However, when the signal line for transmitting the abnormality diagnosis signal fails (open or short), the fuel is not injected even if the fuel is normally injected from the injector. For this reason, there is a problem that the vehicle running is inadvertently stopped despite the fact that the fuel injection can be normally performed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problem, and an object of the present invention is to enable a vehicle to travel in a state where fuel injection is possible even if there is an abnormality in a fuel injection system. It is to provide a fuel injection control device for an internal combustion engine that can be used.

[0006]

According to the first aspect of the present invention, there is provided a driving circuit for controlling a driving current of an injector, and injector control means for outputting an energization signal to the driving circuit. Here, the drive circuit is EDU
The injector control means is embodied by an ECU (electronic control unit). Then, the abnormality detecting means detects whether or not a drive current has flowed through the injector, and outputs a signal indicating that the fuel injection system is abnormal when the current does not flow through the injector in synchronization with the energization signal. Further, the misfire detection means detects misfire for each cylinder of the internal combustion engine. The output availability determination means determines whether or not to continuously output the energization signal based on the detection result by the misfire detection means when the abnormality detection means outputs the abnormality signal.

More specifically, as set forth in claim 2, the output permission / inhibition judging means is configured to output the signal when the misfire detection means does not detect a misfire even when the abnormality detection means outputs an abnormal signal. It is determined that the energization signal is output continuously. That is, the fuel injection by the injector is continuously performed.

[0008] In short, when the abnormality detection means outputs an abnormality signal, a misfire should occur if a fuel injection system abnormality has truly occurred. If misfire is not detected in spite of that, it is considered that the fuel injection system abnormality itself is erroneous. For example, when a signal line for transmitting an abnormal signal has an open or short-circuit failure, there is a possibility that an error may be erroneously diagnosed even though the fuel injection system is normal. On the other hand, according to this configuration, it is possible to specify that the misdiagnosis has been made, so that the normal fuel injection can be continued. As a result, even when there is an abnormality in the fuel injection system, the vehicle can be driven in a state where fuel injection is possible.

[0009] In the invention according to claim 3, the output permission / inhibition judging means is configured to output an abnormal signal when the abnormality detecting means outputs an error signal and when the misfire detecting means detects a misfire.
It is determined to stop outputting the energization signal to the misfiring cylinder. That is, the fuel injection by the injector is stopped for the misfired cylinder. That is, in order to protect the drive circuit (EDU), the output of the energization signal to the misfiring cylinder is prohibited, and the overcurrent is prevented from flowing. Of course, fuel can be injected into other cylinders without misfire to enable traveling.

In the invention according to the fourth aspect, even if an abnormality signal is output by the abnormality detection means, when the misfire is not detected by the misfire detection means, only a warning is issued by the warning means. As a result, the user can detect the occurrence of the abnormality and take appropriate measures such as repairing a necessary part.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. The present embodiment is embodied as a fuel injection control system for a vehicle engine, and the engine is configured as a so-called direct injection type engine in which fuel is directly injected from an injector into a combustion chamber. Electronic control unit (hereinafter referred to as E
The CU is mainly composed of, for example, a well-known microcomputer, and a drive circuit (EDU) for driving the injector is provided separately from the ECU. That is, in the case of the direct injection engine, the fuel pressure is higher than that of the port injection engine, and the drive current of the injector is also higher. Therefore, the ECU and the drive circuit are generally provided separately. Hereinafter, the detailed configuration will be described with reference to the drawings.

FIG. 1 is an overall configuration diagram showing an outline of a fuel injection control system according to the present embodiment. In FIG. 1, the internal combustion engine is configured as a four-cylinder four-cycle spark ignition engine (hereinafter, simply referred to as an engine 1), and an intake pipe 2 and an exhaust pipe 3 are connected to the engine 1. The intake pipe 2 is provided with a throttle valve 5 linked to an accelerator pedal (not shown). The opening of the throttle valve 5 is detected by a throttle opening sensor 6. Further, an intake pressure sensor 8 is provided in the surge tank 7 of the intake pipe 2.

A piston 10 which reciprocates in the vertical direction in the figure is disposed in a cylinder 9 constituting a cylinder of the engine 1, and the piston 10 is connected to a crankshaft (not shown) via a connecting rod 11. Above the piston 10, a combustion chamber 13 defined by the cylinder 9 and the cylinder head 12 is formed. The combustion chamber 13 communicates with the intake pipe 2 and the exhaust pipe 3 via an intake valve 14 and an exhaust valve 15, respectively.

An electromagnetically driven injector 16 is provided for each cylinder in the cylinder 9, and fuel (gasoline) is supplied to the injector 16 from a fuel tank (not shown), and the injector 16 directly injects fuel into the combustion chamber 13. I do. Spark plug 17 disposed on cylinder head 12
Is fired by a high voltage for ignition from an igniter (not shown).

The reference position sensor 18 outputs a pulse signal every 720 ° CA according to the rotation state of the crankshaft.
In addition, the rotation angle sensor 19 also detects a finer crank angle (for example, 30 ° C.) in accordance with the rotation state of the crank angle.
A pulse signal is output for each A).

The ECU 20 includes a well-known CPU, ROM, R
AM, backup RAM, input / output interface (I / O), etc., and the throttle opening sensor 6, intake pressure sensor 8, reference position sensor 18, and rotation angle sensor 1 are provided.
9 to detect the engine operating state such as the throttle opening TH, the intake pressure PM, the reference crank position (G signal) and the engine speed Ne. And E
The CU 20 calculates a control signal such as a fuel injection amount and an ignition timing based on the engine operating state, and performs the fuel injection control and the ignition timing control based on the control signal.

The ECU 20 diagnoses an abnormality in the fuel injection system in accordance with an abnormality diagnosis procedure described later, and when it is diagnosed that an abnormality has occurred, the ECU 20 drives the abnormality warning lamp 21 and other warning buzzers (not shown) to detect the abnormality. Warning.

Here, the drive circuit (EDU) 30 controls the drive current of the injector 16 and is controlled by the ECU.
The injector 16 is turned ON or OFF based on the energization signal IJT transmitted from the ECU 20 to control the fuel injection amount. The energization signal IJT is sent for each injector of each cylinder. In addition, the drive circuit 30 generates an abnormality diagnosis signal Diag indicating whether or not a current has flowed through the injector 16 in synchronization with the energization signal IJT, and outputs the Diag signal to the ECU 20.
To each time.

FIG. 2 is an electric circuit diagram showing the configuration of the drive circuit 30. 2, the ECU 20 outputs energization signals IJT1, IJT2, IJT3, and IJT4 for each cylinder, and the energization signals IJT1 to IJT4 are input to the control circuit 31. The output voltage from the battery + B is DC-D
The voltage is boosted by the C converter 32. Transistor 33
a and 33b are turned on only for a predetermined period according to the energization signals IJT1 to IJT4, and apply the voltage of the DC-DC converter 32 to the injector 16.

The control circuit 31 includes energization signals IJT1 to IJT.
During the period in which T4 is applied, while the drive current flowing through the injector 16 at that time is monitored by the terminal voltages of the resistors 34a and 34b, the transistors 35a and 35b are turned on / off so that the current is maintained at a predetermined current value. Control.

Transistor 36 for driving injector
a, 36b, 36c, and 36d have energization signals IJT1 to IJT1
JT4 is supplied respectively. Then, the corresponding transistor 16 is turned on by the energization signal of the logic high level, and a drive current flows through the injector 16, and the energization signal IJT1
駆 動 IJT4 falls, the driving current is cut off.

The control circuit 31 includes resistors 34a, 34
An abnormality diagnosis signal Diag is generated based on the drive current extracted through the terminal voltage of b. Specifically, the drive current is compared with a predetermined threshold value, and energization signals IJT1-IJT
When the drive current increases with the rise of signal No. 4, the abnormality diagnosis signal Diag falls to a logic low level, and when the drive current is cut off with the fall of the energization signals IJT1 to IJT4, the abnormality diagnosis signal Diag changes to a logic high level. It can be launched in. Then, the abnormality diagnosis signal Diag is sequentially taken into the ECU 20.

Next, the operation of this embodiment will be described. First, the basic operation of the present control system will be described with reference to the time chart of FIG. In the engine 1, the combustion process proceeds in the order of # 1, # 3, # 4, and # 2, and the energization signal IJT1 from the ECU 20 in accordance with the combustion order.
To IJT4 are output. At this time, each energization signal IJT
If the drive current flows normally according to 1 to IJT4, that is, if the injector 16 operates normally, a normal abnormality diagnosis signal Diag synchronized with the energization signals IJT1 to IJT4 is output as illustrated.

In FIG. 4, for example, each of the energization signals IJT1-IJT1
At the rise of JT4, abnormality diagnosis signal Diag of the front cylinder
Is monitored, and if the rise of the abnormality diagnosis signal Diag in the front cylinder is confirmed, it is determined that the abnormality is normal.

The ECU 20 basically determines whether or not the fuel injection system is abnormal based on the abnormality diagnosis signal Diag. In such a case, the following situations (a) and (b) can be considered. That is, (a) The abnormality diagnosis signal Diag indicates an abnormality, and a misfire has occurred. (B) The abnormality diagnosis signal Diag indicates an abnormality, but no misfire has occurred.

In this case, in the case of the above (a), it is considered that normal fuel injection by the injector 16 has not been performed, and a warning such as an abnormal occurrence and a measure such as fuel injection stop (fuel cut) are immediately performed. . In contrast, the above (b)
If, the normal fuel injection is being performed, but only the abnormality diagnosis signal Diag is regarded as abnormal due to, for example, disconnection of the signal line. Therefore, the fuel injection stop process is not performed, and only the warning of the occurrence of the abnormality is provided.

In this embodiment, as shown in FIG. 5, the time TTDC between the compression TDCs of the cylinders is measured, and the presence or absence of misfire is determined based on the time TTDC. For example, if a misfire has occurred in cylinder # 3,
The time TTDC (1) between # 1 TDC and # 3 TDC is #
It is longer than the time TTDC (2) between 3TDC and # 4TDC, and this time TTDC (2) is longer than a predetermined misfire determination level. Therefore, misfire in the # 3 cylinder is determined.

6 and 7 show the energization signal I
An abnormality diagnosis signal Diag synchronized with JT1 to IJT4 cannot be obtained, indicating that the signal Diag indicates that an abnormality has occurred. However, the details will be described later.

FIG. 3 is a flowchart showing an abnormality diagnosis routine executed by the ECU 20, which is started, for example, by the compression TDC of each cylinder. In FIG. 3, the ECU 20 first determines in step 101 whether the abnormality diagnosis signal Diag input from the drive circuit 30 indicates a fuel injection system abnormality. For example, when the abnormality diagnosis signal Diag has a waveform as shown in FIG. 6, it is determined from the abnormality diagnosis signal Diag synchronized with the energization signal IJT3 of the # 3 cylinder that the fuel injection system of the cylinder is abnormal. If YES in step 101, the ECU 20 increments the abnormality counter of the corresponding cylinder (# 3 cylinder in FIG. 6) by "1" in step 102. On the other hand, if step 101 is NO, the ECU 20 proceeds to step 103
Clears the abnormal counter to "0".

Next, the ECU 20 determines in step 104 whether or not a misfire has occurred. Here, as described above, each TDC
If the time TTDC between them is longer than the misfire determination level, it is determined that a misfire has occurred. If YES in step 104 (if there is a misfire), the ECU 20 sets the misfire counter of the corresponding cylinder (# 3 cylinder in FIG. 6) to "1" in step 105.
Only increment. If NO (no misfire), the ECU 20 clears the misfire counter to “0” in step 106.

Thereafter, at step 107, the ECU 20 sets the abnormality counter of the corresponding cylinder at that time to a predetermined value (for example, 1).
6) It is determined whether it is the above or not. The ECU 20
In the next step 108, it is determined whether or not the misfire counter of the corresponding cylinder is equal to or more than a predetermined value (for example, 16). In steps 107 and 108, if the current time is the TDC timing of the # 4 cylinder, the abnormality counter and the misfire counter of the # 3 cylinder are determined.

If step 107 is NO,
The ECU 20 terminates this routine without any abnormality in the fuel injection system. For example, in the case of FIG. 4, it is determined that the fuel injection system is normal for all cylinders.

Steps 107 and 108 are both YE
In the case of S, the ECU 20 proceeds to step 109. For example, in FIG. 6, the abnormality counter is integrated with the abnormality of the abnormality diagnosis signal Diag of the # 3 cylinder.
Is determined to be affirmative. If the abnormality is caused by an actual misfire (fuel injection system abnormality), the misfire counter is added up.
8 is affirmatively determined.

Accordingly, in such a case, the ECU 20 determines at step 109 the corresponding cylinder (# 3 cylinder in FIG. 6) at that time.
Output of the energization signal is prohibited. That is, the energization signal for the # 3 cylinder is maintained at the logic low level. Further, in the following step 110, the ECU 20 turns on the abnormality warning lamp 21 to warn the user of the abnormality of the fuel injection system. And, after the treatment of steps 109 and 110,
This routine ends.

If the terminal of the injector 16 connected to the battery + B (+ side) is short-circuited to the ground (GND), the amount of the injector coil is reduced as a resistance component, so that the drive circuit 30 (transistors 35a and 35b) has an excessive amount. There is a concern that the current may flow and the drive circuit 30 may be broken. However, according to the process of step 109, such a problem is avoided.

On the other hand, if step 107 is YES and step 108 is NO, the ECU 20 skips step 109 and proceeds to step 110. That is, for example, when a signal line for transmitting the abnormality diagnosis signal Diag from the drive circuit 30 to the ECU 20 has an open or short failure, as shown in FIG. 7, the abnormality diagnosis signal Diag is always at a logical high level or a logical low level. Will be retained.
In such a case, since the fuel injection by the injector 16 is performed normally, the misfire counter is not integrated, but only the abnormal counter is integrated. Therefore, the fuel injection is not stopped, and only the warning of the occurrence of the abnormality is issued (step 110).

In this embodiment, the injector control means and the misfire detection means are constituted by the ECU 20, and the output permission / non-permission judgment means is constituted by the routine of FIG. Further, the drive circuit 30 constitutes an abnormality detection unit.

According to this embodiment described in detail above, the following effects can be obtained. (A) When the misfire is not detected even if the drive circuit 30 outputs the abnormality diagnosis signal Diag indicating the abnormality of the fuel injection system, the energization signal IJT to each cylinder is continuously output, and the fuel injection by the injector 16 is continued. I decided to. Thus, even if there is an abnormality in the fuel injection system, the vehicle can be driven in a state where fuel injection is possible.

(B) When the abnormality diagnosis signal Diag is output and a misfire is detected, it is determined that the output of the energization signal IJT to the misfiring cylinder is to be stopped. This prevents the drive circuit 30 from being prevented.

(C) When the misfire is not detected even when the abnormality diagnosis signal Diag is output, only the warning by the abnormality warning lamp 21 is performed, so that the user can detect the occurrence of the abnormality and repair the necessary parts. Appropriate action can be taken.

The embodiments of the present invention can be embodied in the following forms other than the above. In the above embodiment, the time TTDC between the compression TDC of each cylinder is measured, and the time TDC is calculated.
Although the presence / absence of a misfire is detected based on TDC, other misfire detection methods can be used. For example, a misfire may be detected from the rate of increase in the number of revolutions immediately after ignition by the spark plug, or a misfire may be detected by measuring an ion current due to combustion.

In the above-described embodiment, the configuration of FIG. 2 is used as the configuration of the driving circuit 30, but the configuration of the driving circuit 30 is not limited to this. For example, in FIG. 2, the configuration may be such that the transistors 33a and 33b for boost control or the transistors 35a and 35b for constant current control are removed.

At the time of misfire detection, it is confirmed that spark generation by the spark plug has been performed, and based on this, it is determined that injection is abnormal by the injector. In this case, it is possible to reliably determine that the cause of the misfire is an injector abnormality. Alternatively, if the diagnosis information indicating that the cause of the misfire is a spark generation failure due to the spark plug is separately stored, the failure diagnosis becomes easier and more reliable.

In the above embodiment, the present invention is applied to a direct injection gasoline engine. However, application to a port injection gasoline engine is also possible. Further, application to a diesel engine is also possible. The point is that any fuel injection control device provided with a drive circuit for controlling the drive current of the injector separately from the electronic control unit (injector control means) can be arbitrarily applied.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing an outline of a fuel injection control system according to an embodiment of the invention.

FIG. 2 is an electric circuit diagram illustrating a configuration of a driving circuit.

FIG. 3 is a flowchart showing an abnormality diagnosis routine.

FIG. 4 is a time chart for explaining a basic operation of fuel injection.

FIG. 5 is a time chart showing the time between TDC of each cylinder.

FIG. 6 is a time chart showing a signal waveform at the time of abnormality diagnosis.

FIG. 7 is a time chart showing a signal waveform at the time of abnormality diagnosis.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Engine (internal combustion engine), 16 ... Injector, 20
... ECU (electronic control unit) constituting injector control means, misfire detection means, output availability determination means, 21 ... abnormality warning light constituting warning means, 30 ... Drive circuit (EDU) constituting abnormality detection means.

 ────────────────────────────────────────────────── ─── Continued on the front page F term (reference) 3G084 AA00 AA01 BA13 BA33 DA26 DA33 EA07 EA11 EB22 FA00 FA19 FA24 FA34 FA38 3G301 HA01 HA02 HA04 JB02 JB08 JB10 LB02 LB04 MA24 NA08 NE23 PC00B PC09B PE02B PE03B PG02B

Claims (4)

[Claims] 1. An electromagnetically driven injector for injecting fuel into an internal combustion engine, a drive circuit for controlling a drive current of the injector, an injector control means for outputting an energization signal to the drive circuit, and the injector To detect whether the drive current has passed
Abnormality detection means for outputting a signal indicating that there is a fuel injection system abnormality when current does not flow through the injector in synchronization with the energization signal; misfire detection means for detecting misfire for each cylinder of the internal combustion engine; An output enable / disable judging means for judging whether or not to continuously output the energization signal based on a detection result by the misfire detecting means when an abnormal signal is output by the detecting means; A fuel control device for an internal combustion engine. 2. The output permission / inhibition judging means judges that the energization signal is to be continuously output even if an abnormality signal is output by the abnormality detection means and no misfire is detected by the misfire detection means. 2. The fuel control control device for an internal combustion engine for a vehicle according to claim 1. 3. The output availability determination means determines to stop outputting the energization signal to a misfiring cylinder when an abnormality signal is output by the abnormality detection means and a misfire is detected by the misfire detection means. The fuel control control device for a vehicle internal combustion engine according to claim 1, wherein 4. A warning means for warning that an abnormality has occurred. Even if an abnormality signal is output by the abnormality detection means, when a misfire is not detected by the misfire detection means, only a warning by the warning means is issued. The fuel injection control device for a vehicle internal combustion engine according to any one of claims 1 to 3.