JPH0861136A - Drive control device for internal combustion engine - Google Patents

Abstract

PURPOSE: To remarkably improve the accuracy of the diagnosis of misfire by eliminating the misfire due to a lack of fuel from the object of the diagnosis of misfire. CONSTITUTION: During the drive of an engine 1, misfire diagnosing processing is carried out in ordinary, but when the residual quantity of the fuel inside of a fuel tank 12 is reduced to a little or zero, the misfire diagnosing processing is stopped by a diagnosis stopping processing. Namely, at the time of stopping the diagnosis, the existence of the air, which is mixed in the fuel F sucked by a fuel pump 13, is detected on the basis of a change of the driving current for driving the fuel pump 13. Residual quantity of the fuel inside of the fuel tank 12 at a small quantity or zero can be thereby detected, and the misfire diagnosing processing is stopped on the basis of this detection.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive control device for an internal combustion engine used as an engine of an automobile,
In particular, the present invention relates to a drive control device for an internal combustion engine having a function of diagnosing misfire of the internal combustion engine.

[0002]

2. Description of the Related Art Generally, a drive control device for an internal combustion engine used as an engine of an automobile or the like is designed to perform engine misfire diagnosis in order to enhance the safety of traveling of the automobile.

Here, the causes of misfire include malfunction or failure of the fuel injection valve for injecting fuel into the combustion chamber of the engine, malfunction or failure of the spark plug for igniting fuel in the combustion chamber of the engine, and spark plug failure. A disconnection of the ignition coil that generates high-voltage electricity may be considered.

Further, in order to detect the misfire caused by such a cause, normally, the combustion pressure in the combustion chamber is monitored by a combustion pressure sensor provided in the cylinder of the engine, and when the combustion pressure is abnormally decreased, the misfire is detected. I am trying to judge. For example, when the fuel is not sufficiently injected into the combustion chamber of the engine due to a failure of the fuel injection valve or the like, the air-fuel mixture in the combustion chamber is diluted, so that ignition by the spark plug or the like is not performed well and the combustion chamber The combustion pressure of is drastically reduced. This is determined to be a misfire.

[0005]

By the way, in the above-mentioned prior art, the misfire diagnosis is carried out based on the combustion pressure of the engine. However, the combustion pressure of the engine is such that the remaining amount of fuel in the fuel tank is small or zero ( There is a case in which the fuel is so-called "out of gas" and the fuel is not sufficiently supplied to the fuel injection valve, which may cause a large decrease.

That is, when the amount of fuel remaining in the fuel tank becomes small and the vehicle bends in a sharp curve, the liquid level of the fuel in the fuel tank inclines, so the fuel supplied to the engine Air may get inside. As a result, the amount of fuel injected from the fuel injection valve into the combustion chamber of the engine is significantly lower than the calculated amount (injection amount during normal operation), and the combustion pressure of the engine is greatly reduced. Further, even when the fuel in the fuel tank is almost zero, the fuel mixed with air is supplied to the engine, so that the combustion pressure of the engine is greatly reduced.

In the misfire diagnosis according to the prior art, a decrease in the combustion pressure of the engine due to such a gas shortage is also diagnosed as a misfire. Therefore, a misfire due to a simple gas shortage and a malfunction or failure of the fuel injection valve or the spark plug. There is a problem that the accuracy of misfire diagnosis is low because it cannot be distinguished from the original misfire due to the cause.

The present invention has been made in view of the above-mentioned problems of the prior art, and it is possible to exclude a misfire caused by a small amount or zero fuel remaining in the fuel tank from the objects of the misfire diagnosis. An object of the present invention is to provide a drive control device for an internal combustion engine that can significantly improve the accuracy of misfire diagnosis.

[0009]

In order to solve the above-mentioned problems, a drive control device for an internal combustion engine according to a first aspect of the present invention includes an internal combustion engine, a fuel tank for storing fuel used in the internal combustion engine, A fuel pump for discharging the fuel in the fuel tank toward the internal combustion engine, and a fuel pipe for delivering the fuel discharged by the fuel pump to the internal combustion engine,
A fuel injection valve for injecting the fuel delivered through the fuel pipe into the internal combustion engine and a misfire diagnosis means for diagnosing a misfire occurring in the internal combustion engine are adopted.

A feature of the configuration adopted by the invention of claim 1 is that the misfire diagnosis means includes a diagnosis stop means for stopping the misfire diagnosis process when the remaining fuel amount in the fuel tank becomes small or zero. It is provided.

Further, according to the second aspect of the present invention, whether the diagnosis stopping means has a small amount or zero fuel remaining amount in the fuel tank based on the drive current supplied to drive the fuel pump. It is desirable that the misfire diagnosis process is stopped by detecting whether or not the misfire diagnosis process is stopped.

On the other hand, according to the third aspect of the present invention, the diagnosis stopping means determines whether the remaining amount of fuel in the fuel tank is small or zero based on the liquid level of the fuel in the fuel tank. The misfire diagnosis process may be stopped by detecting

Further, as in the invention of claim 4, from the time when the diagnosis stopping means detects that the remaining amount of fuel in the fuel tank is small or zero, the fuel flows from the fuel pump through the fuel pipe. It is desirable to stop the misfire diagnosis process after a predetermined time corresponding to the time required to reach the fuel injection valve.

[0014]

According to the structure of the first aspect, the misfire diagnosis process is always performed by detecting the combustion pressure of the internal combustion engine and the like while the internal combustion engine is being driven. However, if the amount of fuel remaining in the fuel tank is low or zero,
By stopping the misfire diagnosis processing of the misfire diagnosis means by the diagnosis stopping means, the misfire that occurs due to the small amount or zero amount of fuel remaining in the fuel tank can be detected from the target of the misfire diagnosis processing by the misfire diagnosis means. Can be excluded.

That is, when the remaining amount of fuel in the fuel tank becomes small, the fuel is discharged from the fuel pump in a state in which air is mixed, so that the amount of fuel injected from the fuel injection valve (normal It is significantly smaller than the injection amount). It is possible to prevent the misfire diagnosis means from diagnosing the decrease in the combustion pressure of the internal combustion engine due to such a cause as misfire.

When the remaining amount of fuel in the fuel tank becomes zero, no fuel is discharged from the fuel pump and no fuel is injected from the fuel injection valve. It is possible to reliably prevent the misfire diagnosis means from diagnosing the decrease in the combustion pressure of the internal combustion engine due to such a cause as misfire.

According to the second aspect of the invention, when the remaining amount of fuel in the fuel tank becomes small or zero, air is mixed in the fuel sucked by the fuel pump, so that the load of the fuel pump is increased. It will be reduced. As a result, the drive current supplied to the fuel pump to drive the fuel pump is reduced. Then, the diagnosis stopping means can surely detect whether the remaining amount of fuel in the fuel tank is small or zero by judging the decrease of the drive current, and based on this, the misfire diagnosis process can be performed. You can stop.

On the other hand, according to the third aspect of the invention, when the remaining amount of fuel in the fuel tank becomes small or zero, the liquid level of the fuel decreases correspondingly. Based on this, the diagnosis stopping means can detect whether the remaining amount of fuel in the fuel tank is small or zero, and based on this, the misfire diagnosis process can be stopped.

According to the structure of claim 4, from the time when it is detected that the remaining amount of fuel in the fuel tank is small to the time when the fuel flows from the fuel pump through the fuel pipe and reaches the fuel injection valve. After the elapse of a predetermined time corresponding to the required time, the misfire diagnosis processing by the misfire diagnosis means is stopped.

Here, the time difference is set between the detection of the remaining fuel amount and the stop of the misfire diagnosis process.
After the fuel mixed with air is sucked in by the fuel pump, the air flows through the fuel pipe and reaches the fuel injection valve, which significantly reduces the amount of fuel injected from the fuel injection valve. This is because it takes time until the combustion pressure of the engine is reduced.

As a result, the combustion pressure of the internal combustion engine is reduced due to the amount of remaining fuel in the fuel tank becoming small or zero, and only the misfire caused by this is excluded from the targets of the misfire diagnosis processing. be able to.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS. 1 to 9. In the present embodiment, the case where a drive control device for an internal combustion engine is used as a drive control device for an engine of an automobile is taken as an example. I will give you.

First, a first embodiment of the present invention will be described with reference to FIGS. 1 to 6. In FIG. 1, reference numeral 1 denotes an engine as an internal combustion engine mounted on an automobile.
Is composed of a cylinder 2, a piston 3, a cylinder head 4 and a crankshaft (not shown) provided on a crankcase, and the like. Inside the cylinder 2, a combustion chamber 5 is provided between the piston 3 and the cylinder head 4. Is defined. An intake port 4A and an exhaust port (not shown) are formed in the cylinder head 4 so as to communicate with the inside of the combustion chamber 5, and an intake valve 6 is provided at the intake port 4A and an exhaust valve (see FIG. (Not shown). further,
An intake pipe 7 for sucking outside air is provided in the intake port 4A of the cylinder head 4, and an air flow meter 8 for measuring the amount of intake air is provided in the middle of the intake pipe 7. In addition,
The air flow meter 8 is connected to a control unit 25 described later, and the measurement result of the intake air amount is output as a detection signal.

The reference numeral 9 indicates the inside of the combustion chamber 5 and the cylinder head 4
The ignition plug 9 is attached to the ignition plug 9 and the ignition plug 9 ignites a mixture of the fuel sucked into the combustion chamber 5 together with the intake air when a high voltage is applied by an ignition coil (not shown). The high combustion pressure is generated by the combustion. Further, the ignition plug 9 is connected to the control unit 25 and ignites at a predetermined timing by an injection pulse signal output from the control unit 25.

Reference numeral 10 denotes a combustion pressure sensor which is located in the vicinity of the spark plug 9 and is attached to the cylinder head 4. The combustion pressure sensor 10 detects the combustion pressure in the combustion chamber 5, and is shown in FIG. It is connected to the control unit 25 as shown. Then, the combustion pressure sensor 10 outputs a detection signal corresponding to the combustion pressure in the combustion chamber 5 to a control unit 25 described later.

Reference numeral 11 denotes a crank angle sensor provided in the crankcase of the engine. The crank angle sensor 1
Reference numeral 1 denotes a rotation angle of the engine 1 and a crank angle for determining the ignition timing of the air-fuel mixture by the spark plug 9, and as shown in FIG.
Connected to 5. Then, the crank angle sensor 11
Outputs a timing signal to the control unit 25 when a crank angle for determining the ignition timing of the air-fuel mixture by the spark plug 9 is detected.

Reference numeral 12 denotes a fuel tank, and the fuel tank 1
A fuel F such as gasoline for use in the engine 1 is stored in the engine 2.

Reference numeral 13 denotes a fuel pump which is provided in the fuel tank 12 and which sucks the fuel F and discharges it toward the engine 1 side. The fuel pump 13 is a pump casing 13A.
The pump unit 13C is installed by the DC motor unit 13B installed inside
Drive the pump casing 13 through the suction port 13D.
The fuel F sucked into A is constantly discharged toward the engine 1 with a constant discharge pressure. The DC motor unit 13B of the fuel pump 13 is connected to the control unit 25, and is driven by the control unit 25 based on ON / OFF of an engine key (not shown).

Reference numeral 14 is a DC motor portion 13 of the fuel pump 13.
A fuel pump drive current detection unit (hereinafter, referred to as “drive current detection unit 14”) for detecting a drive current applied to B is shown. The drive current detection unit 14 is controlled by a power transistor (not shown). The drive current applied to the DC motor 13B is detected and output to the control unit 25.

Reference numeral 15 denotes a fuel pipe for delivering the fuel F discharged by the fuel pump 13 to the engine 1.
One end of the fuel pipe 15 is connected to the discharge port side of the fuel pump 13, and the other end is connected to a fuel injection valve 16 and a pressure regulator 17, which will be described later, provided in the engine 1.

Reference numeral 16 is an intake port 4A of the cylinder head 4.
Shows a fuel injection valve mounted near the front end side of the intake pipe 7 located near the fuel injection valve 16, and the fuel injection valve 16 is the fuel pipe 1
The fuel F delivered by 5 is injected into the combustion chamber 5 of the engine 1. Further, the fuel injection valve 16 is connected to the control unit 25, and is opened / closed at a predetermined timing and at a predetermined valve opening degree based on a drive current from the control unit 25.

Reference numeral 17 is a pressure regulator, and 18 is a control pressure pipe for guiding intake pressure to the pressure regulator 17. The pressure regulator 17 controls the fuel pressure according to the pressure from the control pressure pipe 18, and returns the surplus fuel. It is returned to the fuel tank 12 through the pipe 19.

Reference numeral 20 denotes a fuel gauge provided in the fuel tank 12, and the fuel gauge 20 is provided with a potentiometer 22 supported by the fuel tank 12 via a support member 21.
And an arm 23 rotatably attached to the potentiometer 22 and a float 24 provided on the tip end side of the arm 23. Further, the fuel gauge 20 is arranged such that the float 24 is displaced upward and downward in response to the liquid surface via the arm 23 and the potentiometer 2 is provided.
Detect with 2. In this way, the fuel gauge 20
The amount of remaining fuel in the fuel tank 12 is measured by detecting the height of the liquid surface of the fuel in the fuel tank 12. Further, as shown in FIG. 2, the fuel gauge 20 is connected to a control unit 25 and outputs the remaining fuel amount in the fuel tank 12 to the control unit 25.

Reference numeral 25 denotes a control unit mounted on an automobile, and the control unit 25 is a CP unit.
U, a memory, a timer, etc. are integrally incorporated into the MPU (multi-processing unit), and the input side of the control unit 25 has an air flow meter 8, a combustion pressure sensor 10, a crank angle sensor, as shown in FIG. 1
1, the drive current detector 14 and the fuel gauge 20 are connected, and the output side is connected with the spark plug 9, the fuel pump 13, the fuel injection valve 16 and the like.

On the other hand, the memory 25A of the control unit 25 stores a misfire diagnosis program as a misfire diagnosis means for diagnosing a misfire caused by a malfunction or failure of the fuel injection valve 16 or the engine 1.
The misfire diagnosis program is executed by the crank angle sensor 1
The misfire diagnosis process is performed by reading the detection signal from the combustion pressure sensor 10 and detecting the combustion pressure in the combustion chamber 5 of the engine 1 at a timing based on the timing signal from 1. Furthermore, the misfire diagnosis program includes
A diagnostic stop program (FIG. 4) is provided as a diagnostic stop means for stopping the misfire diagnosis process when the remaining amount of fuel in the fuel tank 12 becomes small or zero. Further, the memory 25A of the control unit 25 stores a fuel transportation time setting map M (FIG. 6).

The drive control system for the engine according to this embodiment has the above-mentioned construction. Next, the misfire diagnosis will be explained.

That is, while the engine 1 is being driven, as shown in FIG. 3, the control unit 25 executes the misfire diagnosis processing by the misfire diagnosis program and the diagnosis stop processing by the diagnosis stop program in parallel. The misfire diagnosis process is stopped when the stop interrupt is generated by the diagnosis stop process, and the misfire diagnosis process is restarted when the restart interrupt is generated by the diagnosis stop process.

Here, the main operation of the misfire diagnosis process will be described. First, the control unit 25 recognizes the timing at which the spark plug 9 is ignited in the combustion chamber 5 of the engine 1 based on the timing signal from the crank angle sensor 11. Then, at this timing, the combustion pressure sensor 1
The detection signal from 0 is read to determine whether or not the combustion pressure is normal. Here, when it is determined that the combustion pressure is abnormally low, it means that the ignition by the spark plug 9 has not been satisfactorily performed, and thus the misfire is diagnosed. When the occurrence of misfire is diagnosed, the main routine is interrupted, and another processing routine for coping with the occurrence of misfire is started. Further, the misfire diagnosis process is stopped by a stop interrupt generated by the diagnosis stop process and restarted by a restart interrupt.

Next, the diagnostic stop program will be described with reference to the flowchart of FIG. In steps 1 to 3 in FIG. 4, the control unit 25 controls the fuel pump 1
The drive current output from the drive current detection unit 14 provided in No. 3 is taken in, and the change amount ΔI of the current value I within a predetermined time is measured. With this, it is detected whether or not air is mixed in the fuel F sucked by the fuel pump 13, and based on this result, it is determined whether or not the remaining fuel amount in the fuel tank 12 is small or zero. .

That is, when the fuel tank 12 is sufficiently filled with the fuel F, air is introduced into the fuel F sucked from the suction port 13D of the fuel pump 13 arranged at the bottom of the fuel tank 12. It does not mix. Therefore, the discharge amount of the fuel pump 13 is always stable, and the current value I of the drive current is
Also is constant as shown by the characteristic line P in FIG.

On the other hand, when the remaining amount of fuel in the fuel tank 12 becomes small or becomes zero and the liquid level of the fuel comes close to the bottom surface of the fuel tank 12, the suction port 1 of the fuel pump 13
Air is mixed in the fuel F sucked from 3D. Then, the discharge amount of the fuel pump 13 is reduced, and the load of the pump portion 13C of the fuel pump 13 is reduced due to the mixture of air, so that the current value I of the drive current is shown by the characteristic line Q in FIG. To decrease.

In order to detect the decrease of the current value I of the drive current supplied to the fuel pump 13, that is, the variation ΔI of the current value I within a predetermined time, in step 1, t1 is set.
Current value I1 of the drive current at time t2 and time t2 (for example, t1
The current value I2 of the drive current at the time point (after a lapse of 20 .mu.s from the time) is detected, and in step 2, the current value I2 is subtracted from the current value I1 to obtain the variation .DELTA.I, and step 3
Then, the change amount ΔI is compared with the predetermined amount A. If the amount of change ΔI is equal to or greater than the predetermined amount A (ΔI ≧ A), it means that air is mixed in the fuel F sucked into the fuel pump 13, so that “YES” is determined and step 4 is executed. If the change amount ΔI is smaller than the predetermined amount A (ΔI <A), it is judged as “NO” because air is not mixed, the process proceeds to step 8 and returns.

Here, the predetermined amount A is the current value I of the drive current.
If the amount of change ΔI is larger than this, it is a known value (for example, 3 A) that can be empirically determined to be a state in which air is mixed in the fuel F sucked into the fuel pump 13, and the preset control is performed. It is stored in the memory 25A of the unit 25.

Next, in step 4, the timer built in the control unit 25 is used to make the current processing wait for the fuel transportation time B. Here, the fuel transportation time B is a time corresponding to the time required for the fuel F to flow from the fuel pump 13 through the fuel pipe 15 to reach the fuel injection valve 16. Further, since the fuel transportation time B varies depending on the engine speed at that time, the basic fuel injection amount into the combustion chamber 5, and the like, the fuel transportation time setting map M as shown in FIG. 6 is referred to. Set time B.

Here, the setting of the fuel transportation time B based on the fuel transportation time setting map M will be described with reference to FIG. First, the control unit 25 determines the rotation speed N of the engine 1 and the basic fuel injection amount Tp based on the detection signals from the crank angle sensor 11, the air flow meter 8 and the like. Then, the points on the characteristic lines r, r, ... Are specified from the rotation speed N and the basic fuel injection amount Tp, and the areas s, s, ... (the portion surrounded by the dotted line in FIG. 6) to which the points belong are identified. Identify. Then, the fuel transportation time B set in advance corresponding to the area s at this time is read.

As described above, the fuel transportation time B is precisely set by the fuel transportation time setting map M, but in general, when both the rotational speed and the basic fuel injection amount are small values (for example, during idling). The fuel transportation time B is set to a long time, and when the rotation speed N and the basic fuel injection amount Tp are both large values (for example, during acceleration), the fuel transportation time B is set to a short time.

In the step 4, while waiting for the fuel transportation time B, the air in the fuel F sucked by the fuel pump 13 flows through the fuel pipe 15 and the fuel injection valve 1
6 will be reached. Then, after the fuel transportation time B has elapsed, the process proceeds to step 5.

Next, in step 5, a stop interrupt for stopping the misfire diagnosis processing which is executed in parallel with the diagnosis stop processing is generated, and the misfire diagnosis processing is stopped.

Next, at step 6, the timer built in the control unit 25 is used to make the current processing wait for the stop maintaining time C. Here, the reason for waiting for the stop maintaining time C is as follows.

For example, since the fuel F in the fuel tank 12 is violently shaken by a strong external vibration and the liquid level of the fuel F is greatly inclined for a moment, air is briefly absorbed in the fuel F sucked by the fuel pump 13. When the air is mixed, the combustion pressure of the engine 1 is reduced even by this momentary mixture of air, and it takes some time for the combustion pressure to return to the normal combustion pressure. This is because it is necessary to maintain the misfire diagnosis process in a stopped state from the time when the combustion pressure decreases to the time when the combustion pressure returns to the normal combustion pressure. Therefore, the stop maintaining time C is set to about 10 seconds, for example. And the stop maintaining time C
Is passed, the process proceeds to step 7.

Next, at step 7, a restart interrupt for restarting the misfire diagnosis processing is generated, and the misfire diagnosis processing is restarted. Then, the process returns in step 8.

Thus, according to the present embodiment, the diagnosis stop program is configured to stop the misfire diagnosis process when the remaining fuel amount in the fuel tank becomes small or zero. When the remaining amount becomes small or becomes zero (so-called gas shortage), the fuel pump 13
It is possible to exclude from the target of the misfire diagnosis process, the misfire that occurs when air is mixed in the fuel F sucked in by the air and the ignition is not satisfactorily ignited by the spark plug 9 due to the air.

For example, when the vehicle runs in a sharp curve when the remaining amount of fuel in the fuel tank 12 is small,
The liquid level of the fuel in the fuel tank 12 is inclined as shown by the chain double-dashed line in FIG. As a result, air may be mixed in the fuel F sucked by the fuel pump 13, and the ignition by the spark plug 9 may not be performed properly. But,
In such a case, since the misfire diagnosis process is stopped by the diagnosis stop process, it is not determined that a misfire has occurred. That is, it is possible to prevent the occurrence of a misfire from being diagnosed simply by causing an automobile in a gas-deficient state to bend in a sharp curve.

Therefore, according to the present embodiment, there is a possibility of causing a serious accident by distinguishing a misfire due to a simple gas shortage or the like and an original misfire due to a malfunction or failure of the fuel injection valve 16 or the spark plug 9. Only certain inherent misfires can be reliably diagnosed, and the accuracy of misfire diagnosis can be greatly improved.

Further, according to the diagnosis stop processing according to the present embodiment, the stop interrupt is generated after the fuel transportation time B has elapsed from the time when air is mixed into the fuel F sucked by the fuel pump 13, and the misfire diagnosis processing is performed. Since the configuration described above is stopped, the misfire diagnosis process can be stopped from the time when the air mixed in the fuel F sucked into the fuel pump 13 actually reaches the fuel injection valve 16. As a result, the misfire diagnosis process can be stopped immediately before the ignition failure occurs due to the inclusion of air in the fuel F. Therefore, the misfire diagnosis process can be accurately stopped from the time when it really needs to be stopped. It is possible to improve the accuracy of the misfire diagnosis.

Next, a second embodiment of the present invention will be described with reference to FIGS. 7 and 8. The feature of this embodiment is that the level of the fuel in the fuel tank is measured in the misfire diagnosis. By doing so, it is detected whether or not the remaining amount of fuel in the fuel tank is small or zero, and the misfire diagnosis process is stopped based on this. In this embodiment, the same components as those in the first embodiment shown in FIGS. 1 and 2 described above are designated by the same reference numerals, and the description thereof will be omitted.

In the figure, 31 indicates a control unit according to the present embodiment mounted on an automobile, and the control unit 31 is an MPU (multiprocessing unit) which is substantially the same as the control unit 25 according to the first embodiment. An air flow meter 8, a combustion pressure sensor 10, a crank angle sensor 11, a fuel gauge 20, etc. are connected to the input side of the control unit 31, and an ignition plug 9, a fuel pump 13, a fuel injection valve 16 etc. are connected to the output side. Are connected.

Further, the memory 31A of the control unit 31 stores a misfire diagnosis program for performing a misfire diagnosis process substantially similar to that described in the first embodiment, and this misfire diagnosis program stores the fuel in the fuel tank 12. A diagnostic stop program is provided as a diagnostic stop means for stopping the misfire diagnosis process when the remaining amount becomes small or zero.

However, the diagnostic stop program (FIG. 8) according to the present embodiment is different from that described in the first embodiment, and the detection signal (hereinafter referred to as "fuel" output from the fuel gauge 20 to the control unit 25 is used. "Remaining signal h")
The remaining fuel amount in the fuel tank 12 is recognized based on the above.

The engine drive control apparatus according to this embodiment has the above-mentioned configuration. Next, the diagnosis stop processing by the diagnosis stop program according to this embodiment will be described with reference to FIG.
As described below, the diagnosis stop program is always executed in parallel with the misfire diagnosis processing by the misfire diagnosis processing program while the engine 1 is being driven.

First, in step 11, the fuel level signal h output from the fuel gauge 20 to the control unit 25 is read, and in step 12, the fuel level signal h is compared with a predetermined value D.

Here, the fuel remaining amount signal h indicates that the fuel tank 1
2 is a signal corresponding to the liquid level height of the fuel F stored in No. 2. As a result, the voltage value of the remaining fuel amount signal h changes in accordance with the change in the liquid level height of the fuel F stored in the fuel tank 12. For example, when the remaining fuel amount in the fuel tank 12 is zero, the remaining fuel amount signal h is 0V, and when the fuel tank 12 is full, the remaining fuel amount signal h is 5V.

Further, the predetermined value D corresponds to a state where air may be mixed in the fuel F sucked by the fuel pump 13 when the liquid level of the fuel F in the fuel tank 12 is lower than this. Is the voltage value of the remaining fuel level signal h
For example, it is set to about 500 mV. The predetermined value D is a known value obtained empirically in the past, and the liquid level of the fuel F in the fuel tank 12 is inclined by the vibration of the vehicle, so that the fuel F sucked by the fuel pump 13 is absorbed. It is set in consideration of the inclusion of air.
The predetermined value D is stored in the memory 31A of the control unit 31 in advance.

Therefore, when the remaining fuel amount signal h is smaller than the predetermined value D, air may be mixed in the fuel F sucked by the fuel pump 13, so that a "YES" determination is made, and the routine proceeds to step 13. On the other hand, the remaining fuel amount signal h is the predetermined value D
In the above case, there is no possibility that air will be mixed in the fuel F sucked by the fuel pump 13, so it is determined to be "NO", the process proceeds to step 17, and the process returns.

Next, in step 13, the timer built in the control unit 25 is used to make the current processing wait for the fuel transportation time B. The fuel transportation time B is the same as that described in the first embodiment. That is, the fuel transportation time B is a time corresponding to the time required for the fuel F to flow from the fuel pump 13 through the fuel pipe 15 to reach the fuel injection valve 16, and the number of revolutions of the engine 1
It is set by the basic fuel injection amount and fuel transportation time setting map.

Next, at step 14, a stop interrupt for stopping the misfire diagnosis processing executed in parallel with the diagnosis stop processing is generated, and the misfire diagnosis processing is stopped.
Then, in step 15, the control unit 25
The current processing is stopped by using the timer built in
Just wait.

Next, at step 16, a restart interrupt for restarting the misfire diagnosis processing is generated to restart the misfire diagnosis processing. Then, the process returns in step 17.

Thus, according to this embodiment, the fuel remaining amount in the fuel tank 12 is small or small on the basis of the fuel remaining amount signal h corresponding to the liquid level height of the fuel F stored in the fuel tank 12. Even if it is configured to recognize whether it is zero and stop the misfire diagnosis process when the remaining fuel amount becomes small or becomes zero, it is possible to obtain substantially the same effect as that of the first embodiment.

In each of the above-mentioned embodiments, the misfire diagnosis process and the diagnosis stop process are executed in parallel, and when the remaining fuel amount in the fuel tank 12 becomes small or zero, the misfire diagnosis process is executed by the diagnosis stop process side. Although it has been described that an interrupt for stopping is generated, the present invention is not limited to this, and the misfire diagnosis process (step 21) and the diagnosis stop process (step 22) as a subroutine are sequentially executed in the main routine shown in FIG. You may do it.

Further, in each of the above embodiments, the combustion pressure sensor 1
Although the misfire diagnosis is described by detecting the combustion pressure in the combustion chamber 5 of the engine 1 using 0, the present invention is not limited to this, and the crank angle sensor, the combustion temperature sensor,
The misfire diagnosis may be performed by various sensors such as a disconnection detector.

Further, the present invention can be applied regardless of whether it is a gasoline vehicle or a diesel vehicle. Further, the present invention is not limited to the drive control device of the engine of the vehicle, but other vehicles or industrial machines. It is also widely applicable as a drive control device for an internal combustion engine.

[0072]

As described above in detail, according to the invention of claim 1, the misfire diagnosis means is provided with a diagnosis stop means for stopping the misfire diagnosis process when the remaining amount of fuel in the fuel tank becomes small or zero. Since the configuration is provided, it is possible to exclude a misfire caused by a small amount of fuel remaining in the fuel tank or zero in the misfire diagnosis. Therefore, it is possible to reliably diagnose only the misfire that is caused by the failure of the fuel injection valve, the ignition system, etc., and it is possible to greatly improve the accuracy and reliability of the misfire diagnosis.

In particular, according to the second aspect of the present invention, in the diagnosis stopping means, it is determined whether the remaining fuel amount in the fuel tank is small or zero based on the drive current supplied to drive the fuel pump. Therefore, based on the detection result, the misfire diagnosis processing by the misfire diagnosis means can be reliably stopped only when the remaining fuel amount in the fuel tank becomes small or zero.

According to the third aspect of the invention, the diagnosis stopping means detects whether the remaining amount of fuel in the fuel tank is small or zero based on the liquid level of the fuel in the fuel tank. Even with such a configuration, the misfire diagnosis processing by the misfire diagnosis means can be reliably stopped only when the remaining fuel amount in the fuel tank becomes small or zero based on the detection result.

Further, according to the invention of claim 4, the combustion pressure of the internal combustion engine is lowered due to the small amount or zero of the remaining fuel amount in the fuel tank, which causes only the misfire. It can be excluded from the target of the misfire diagnosis processing, and the accuracy of the misfire diagnosis can be further improved.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram showing an engine drive control device according to a first embodiment of the present invention.

FIG. 2 is a control block diagram showing a drive control device for an engine according to a first embodiment.

FIG. 3 is an explanatory diagram showing a state in which a misfire diagnosis program and a diagnosis stop program are executed in parallel.

FIG. 4 is a flowchart showing a diagnosis stop process according to the first embodiment.

FIG. 5 is a characteristic diagram showing characteristics of a drive current supplied to a fuel pump.

FIG. 6 is an explanatory diagram showing a fuel transportation time setting map.

FIG. 7 is a control block diagram showing an engine drive controller according to a second embodiment.

FIG. 8 is a flowchart showing a diagnosis stop process according to a second embodiment.

FIG. 9 is a flowchart showing a main routine for activating a misfire diagnosis process and a diagnosis stop process.

[Explanation of reference numerals] 1 engine (internal combustion engine) 12 fuel tank 13 fuel pump 15 fuel pipe 16 fuel injection valve 20 fuel gauge 25, 31 control unit

Claims (4)

[Claims] 1. An internal combustion engine, a fuel tank for storing the fuel used in the internal combustion engine, a fuel pump for discharging the fuel in the fuel tank toward the internal combustion engine, and a fuel pump for discharging the fuel. A fuel pipe for delivering fuel to the internal combustion engine, a fuel injection valve for injecting the fuel delivered by the fuel pipe into the internal combustion engine, and a misfire diagnosing means for diagnosing misfire occurring in the internal combustion engine. In the drive control apparatus for an internal combustion engine, the misfire diagnosis means is provided with a diagnosis stop means for stopping the misfire diagnosis process when the remaining fuel amount in the fuel tank becomes small or zero. Engine drive controller. 2. The diagnostic stop means detects whether the remaining amount of fuel in the fuel tank is small or zero based on a drive current supplied to drive the fuel pump, The drive control device for an internal combustion engine according to claim 1, wherein the misfire diagnosis process is stopped. 3. The diagnostic stopping means detects whether the remaining amount of fuel in the fuel tank is small or zero based on the liquid level height of the fuel in the fuel tank,
The drive control device for an internal combustion engine according to claim 1, wherein the misfire diagnosis process is stopped. 4. The diagnostic stop means detects that the remaining amount of fuel in the fuel tank is small or zero,
The internal combustion engine according to claim 1, wherein the misfire diagnosis process is stopped after a predetermined time corresponding to a time required for the fuel to flow from the fuel pump through the fuel pipe to reach the fuel injection valve. Engine drive controller.