JP2002221066A - Fuel injection device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel injection device for internal combustion engine capable of diagnosing a failure in a coil driving means of a fuel injection valve furnished with two exciting coils, a valve opening coil and retention coil, and of executing the fuel injection control in accordance with the failed condition in an eventual case when a failure diagnosis is passed. SOLUTION: The fuel injection device of the internal combustion engine is equipped with the fuel injection valve having the valve opening coil and retention coil and a control device, wherein the control device is furnished with a means to sense the peak value of current flowing in the valve opening coil and a means to make a failure diagnosis by judging that the peak amperage or a value based upon it is over the preset failure judgement threshold or below another failure judgement threshold set otherwise, and the failure diagnosing means gives a failure diagnosis when the described condition of the peak amperage lasts exceeding the specified failure judgement period.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection device for an internal combustion engine, and more particularly to a fuel injection device for an internal combustion engine that is suitable for diagnosing a failure of an exciting coil of a fuel injection valve and controlling fuel injection when a failure occurs.

[0002]

2. Description of the Related Art An electromagnetic fuel injection valve provided with an excitation coil is used as a fuel injection valve of a fuel injection device for an internal combustion engine. The fuel injection valve is generated by energizing the excitation coil. The valve element is attracted by the magnetic force generated, the valve element is pulled away from the valve seat, the fuel injection passage is opened, and fuel is injected from a fuel injection hole formed at the tip.

The fuel injection device of the internal combustion engine includes a drive means for intermittently driving the excitation coil in order to operate the fuel injection valve in synchronization with the rotation of the internal combustion engine or the like. The driving means has been proposed in various ways.

For example, Japanese Patent Application Laid-Open No. 11-13524 discloses a drive control system for a fuel injection valve provided with an exciting coil, which is provided with a valve opening current diagnosing means for diagnosing an abnormality in a system for applying a valve opening current to the exciting coil. And providing that when it is diagnosed that an abnormality has occurred in the system that applies the valve-opening current to the exciting coil, it stops supplying the valve-opening current to the fuel injection valve, and applies a holding current to open the fuel injection valve. It is disclosed to provide a backup control means for causing a valve opening current diagnostic means for performing a valve opening current diagnostic on the excitation coil, as a valve opening current diagnosing means, in which a normal current value characteristic and an actually detected current value characteristic are provided. A technique for performing abnormality diagnosis of a system that gives a valve opening current to an exciting coil based on the above is disclosed.

In Japanese Patent Publication No. 4-500399, at least two switching elements which can be controlled independently of each other are provided in a drive control circuit of a solenoid valve for fuel injection in a fuel injection device for an internal combustion engine. To supply different magnitudes of voltage to the solenoid valve,
There is disclosed a technique of performing control to open a solenoid valve by supplying a large voltage and then to maintain a valve open state of the solenoid valve by supplying a low voltage.

[0006]

However, the above two techniques require a boost control circuit to drive the fuel injection valve (solenoid valve), so that the fuel injection device of the internal combustion engine becomes expensive. There is a problem that.

Therefore, in order to provide a simple and inexpensive fuel injection device with the above drive circuit, two exciting coils are employed in the electromagnetic fuel injection valve, one of which is used for opening the valve body and the other is used for opening the valve. An electromagnetic fuel injection valve using an exciting coil for holding the valve body open has been developed, and the fuel injection device includes:
Normally, the energization time of the valve opening excitation coil is corrected according to the power supply voltage and the fuel pressure which is the pressure of the fuel pipe of the internal combustion engine.

For this reason, a fuel injection valve provided with two excitation coils can control the fuel injection amount without requiring an expensive drive circuit. If the drive means, and the holding coil and the holding coil drive means are damaged and the optimal fuel injection function is impaired, there is a problem that the operability and exhaust emission of the internal combustion engine are adversely affected. there were.

Japanese Patent Application Laid-Open No. 11-13524 discloses a valve-opening current diagnostic unit and a backup current-diagnosing unit for diagnosing an abnormality in a system for supplying a valve-opening current to an excitation coil in a drive control system for a fuel injection valve having an excitation coil. It is disclosed to provide control means, but since the fuel injection valve has one excitation coil and requires a boost control circuit, the fuel injection valve includes a valve opening coil and a holding coil. The valve drive control system has a different configuration, and no particular consideration is given to the reliability of the detected current value characteristic.

A fuel injection device for an internal combustion engine according to the present invention has been made in view of the above points, and an object thereof is to provide a fuel injection device having two excitation coils, a valve opening coil and a holding coil. It is an object of the present invention to provide a fuel injection device for an internal combustion engine that can diagnose a failure of a coil driving means of a valve and perform fuel injection control according to the failure state even when the failure is diagnosed.

[0011]

In order to achieve the above object,
A fuel injection device for an internal combustion engine according to the present invention particularly includes a fuel injection valve having a valve opening coil and a holding coil, and a control device, and the control device detects a peak current value flowing through the valve opening coil. Means for determining whether the peak current value or the value based on the peak current value is equal to or greater than a preset failure determination threshold, or is equal to or less than another set failure determination threshold. A means for diagnosing a failure, and a drive circuit for controlling energization of the two coils for opening and closing the fuel injection valve, wherein the failure diagnosis means, the peak current value or a value based on the peak current value, If the above state is continued for a predetermined failure determination period or longer, a failure is diagnosed.

In the fuel injection device for an internal combustion engine according to the present invention having the above-described configuration, the control device includes a failure diagnosis unit for the excitation coil of the fuel injection valve. To properly diagnose a failure and apply the result of the diagnosis to the subsequent control of the fuel injection device to perform appropriate air-fuel ratio control, thereby preventing deterioration in operability and exhaust emission of the internal combustion engine. Can be. In addition, the peak current value flowing through the valve-opening coil is compared with a preset failure determination threshold value for determination, and it is determined whether the peak current value has continued for a predetermined failure determination period or longer. By diagnosing the failure of the valve coil, the reliability of the detected peak current value is secured and the abnormality is diagnosed.
Failure diagnosis can be performed accurately and accurately.

In another aspect of the fuel injection device for an internal combustion engine according to the present invention, the control device detects a peak current value flowing through the valve opening coil, and detects an operation state of the internal combustion engine. Means for calculating a basic pulse width for driving the valve-opening coil in accordance with the operating state of the internal combustion engine; means for calculating a target valve-opening current value; Means for performing feedback control of the valve-opening coil drive pulse width so as to obtain a value, calculating a difference between the target valve-opening current calculation value and the peak current value, and calculating the current value difference or the current value difference. When the value based on the state is equal to or greater than a preset failure determination threshold, or in a state equal to or less than another preset failure determination threshold,
Means for diagnosing a failure of the fuel injection valve by determining that the valve opening coil is abnormal, wherein the failure diagnosing means determines whether the peak current value or the value based on the peak current value indicates the state for a predetermined failure determination period. When the above is continued, it is characterized that a failure is diagnosed.

The fuel injection device for an internal combustion engine of the present invention configured as described above calculates the difference between the target valve opening current calculation value calculated from the operating state of the internal combustion engine and the peak current value of the valve opening coil. Since the valve-opening coil is determined to be abnormal based on whether the current value difference or a value based on the current value difference is outside a preset failure determination threshold value, the valve-opening coil is determined based on the operability of the internal combustion engine. Abnormalities can be diagnosed.
In addition, since a means for performing feedback control of the valve opening coil drive pulse width so that the peak current value becomes the target valve opening current value is provided, the peak current value or a value based on the peak current value is compared with the target valve opening current value. The air-fuel ratio control of the internal combustion engine is performed by correcting the valve opening coil drive pulse width based on the state of
Deterioration of operability and exhaust emission of the internal combustion engine can be prevented.

In a specific aspect of the fuel injection device for an internal combustion engine according to the present invention, the failure determination period is calculated for each fuel injection or each rotation speed of the internal combustion engine. I have.

Further, in another specific aspect of the fuel injection device for an internal combustion engine according to the present invention, the failure determination threshold value includes a parameter including at least one of a valve opening coil drive pulse width and a power supply voltage. And one of the failure determination thresholds is set as a fixed value.

Still further, in still another aspect of the fuel injection device for an internal combustion engine according to the present invention, the control device detects the presence or absence of a current return (back electromotive force) generated when power supply to the valve opening coil is cut off. If the state in which the current return has not occurred has continued for a predetermined period, the valve opening coil is determined to be abnormal by determining that the valve opening coil is disconnected or short-circuited, and the functional failure of the fuel injection valve is determined. And a current return (back electromotive force) generated when the control device cuts off the power supply to the holding coil.
If the presence / absence is detected and the state in which the current return does not occur continues for a predetermined period, the holding coil is determined to be disconnected or short-circuited, thereby causing the holding coil to be abnormal and causing a malfunction of the fuel injection valve. Is determined, and the failure determination period in a state where the current return does not occur is calculated for each fuel injection or for each rotation speed of the internal combustion engine.

Still another specific aspect of the fuel injection device for an internal combustion engine according to the present invention is that the control device determines that the malfunction of the fuel injection valve due to the abnormality of the valve opening coil. Is characterized in that the supply of the valve-opening coil drive pulse for all cylinders is cut, and the fuel injection control is performed only with the holding coil, and when the fuel injection control is performed only with the holding coil, the holding coil drive pulse width is reduced. It is characterized in that it is corrected to be longer.

Still another specific aspect of the fuel injection device for an internal combustion engine according to the present invention is such that the control device variably controls a pressure (fuel pressure) in a fuel pipe supplied to the internal combustion engine. When the fuel injection control is performed only by the holding coil, the fuel pressure is controlled such that the pressure (fuel pressure) in the fuel pipe supplied to the internal combustion engine becomes equal to or lower than a predetermined value.

Still further, in still another specific embodiment of the fuel injection device for an internal combustion engine according to the present invention, the control device is configured to determine whether a malfunction of the fuel injection valve is determined due to an abnormality in the valve opening coil. Is characterized in that a fuel cut of a cylinder corresponding to the failure determination (cutting of a valve opening coil drive pulse and a holding coil drive pulse supply) is performed, and when a malfunction of the fuel injection valve is determined due to an abnormality of a holding coil. Is characterized in that the fuel cut of the cylinder corresponding to the failure determination is cut (the supply of the valve opening coil drive pulse and the supply of the hold coil drive pulse is cut), and when the function failure of the fuel injection valve is determined, the rotation of the internal combustion engine is determined. When the number of rotations becomes equal to or more than a predetermined rotation, fuel cut of all the cylinders (cutting of the valve opening coil drive pulse and the holding coil drive pulse supply) is performed. Still another specific aspect of the fuel injection device for an internal combustion engine according to the present invention is characterized in that the air-fuel ratio feedback control is not performed when the malfunction of the fuel injection valve is determined. .

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the fuel injection device for an internal combustion engine according to the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a diagram showing the overall control system configuration of a direct injection internal combustion engine provided with the fuel injection device for an internal combustion engine of the present embodiment. In FIG. 1, air taken into an internal combustion engine 1 is taken in from an input section 4 of an air cleaner 3, passes through an intake air meter 5, passes through a throttle valve body 7 provided with a throttle valve 6 for controlling a suction flow rate, and flows through a collector. Enter 8. The throttle valve 6 is connected to a motor 10 for driving the throttle valve 6, and by driving the motor 10, the throttle valve 6 is operated to control the amount of intake air. The intake air reaching the collector 8 is distributed to an intake pipe 19 connected to each cylinder 2 of the internal combustion engine 1 and guided to a combustion chamber 2a in the cylinder 2.

Further, the exhaust gas burned in the combustion chamber 2a of the internal combustion engine 1 is guided to an exhaust pipe 28 and discharged to the outside of the internal combustion engine 1 via a catalyst (not shown). On the other hand, fuel such as gasoline is sucked and pressurized from a fuel tank 11 by a fuel pump 12 and supplied to a fuel system in which a fuel injection valve 13 and a variable fuel pressure regulator 14 for controlling a fuel pressure within a predetermined range are provided. Is done. The fuel is supplied to a fuel injection valve 13 having a fuel injection opening in a combustion chamber 2a of each cylinder 2.
From the combustion chamber 2a. The air flowing into the combustion chamber 2a and the injected fuel are mixed, and
The fuel is ignited by the spark plug 35 by the piezoelectricity from and burned.

A signal indicating the flow rate of the intake air is output from the air meter 5, and the control unit (control device) 15
The throttle valve body 7 has a throttle sensor 1 for detecting the opening degree of the throttle valve 6.
8 is attached, and its output is also input to the control unit 15.

The crank angle sensor 16 is driven to rotate by the cam shaft 27 of the internal combustion engine 1 and detects the rotational position of the crank shaft with an accuracy of at least about 1 to 10 degrees. A signal from the crank angle sensor 16 is also input to the control unit 15. Exhaust pipe 28
The A / F sensor 20 provided in the unit detects and outputs the actual operating air-fuel ratio from the exhaust gas component, and the signal is also input to the control unit 15.

An ignition switch 33 and a control relay 31 are provided between the control unit 15 and the battery 30, and power is input to the control unit 15 via the ignition switch 33 and the control relay 31. Based on each signal of the sensor, the calculation means 26 calculates the fuel injection timing, the injection flow rate (pulse width control of the fuel injection valve), the ignition timing, and the like to control each control unit of the internal combustion engine 1. . Further, a signal is output from the control unit 15 to a warning device 32 including various warning lights.

FIG. 2 shows the failure diagnosis means 15A of the control device 15 relating to the fuel injection device of the internal combustion engine 1 of the present embodiment. The fuel injection valve 13 is composed of two coils, a valve opening coil 13a and a holding coil 13b, and the power from the battery 30 is supplied to the fuses 43a and 43b and the relay 44.
Is led to the valve opening coil 13a and the holding coil 13b of the fuel injection valve 13 through the valve.

The drive of the valve-opening coil 13a is controlled by ON / OFF control of the energization by a drive transistor 46. Similarly, one of the holding coils 13b is turned on and off by the drive transistor 47.
Drive control is performed by performing F control. The valve opening coil 1
The current flowing through 3a is detected via a current detection resistor (shunt resistor) 15d provided downstream of the valve-opening coil drive transistor 46 and a current detection circuit 15b.

The valve-opening coil drive transistor 4
The disconnection diagnosis circuit 15a connected from the upstream side of the circuit 6 detects the presence or absence of a current return that occurs when power is cut off by the valve opening drive transistor 46, and diagnoses a disconnection / short failure of the valve opening coil 13a. When the valve-opening coil 13a is normally energized, the current return occurs immediately after the energization is cut off by the valve-opening drive transistor 46. No return occurs. Similarly, the disconnection diagnosis circuit 15c detects a disconnection / short-circuit failure of the holding coil 13b.

The current detection circuit 15 for the valve opening coil 13a
Based on the valve opening coil current value detected in step b, the valve opening coil disconnection diagnosis means 40b of the failure detection unit 40 diagnoses the valve opening coil abnormal current. The occurrence of the current return detected by the valve opening coil disconnection diagnosis circuit 15a is diagnosed by the valve opening coil disconnection diagnosis means 40a for valve opening coil disconnection / short circuit failure. Similarly, the presence / absence of the current return detected by the holding coil disconnection diagnosis circuit 15c is diagnosed by the holding coil disconnection diagnosis means 40c for valve opening coil disconnection / short circuit failure.

The diagnostic blocks 40a, 40b, 40c
When a failure is detected by any one of the above, the failure determination operation unit 41 makes a failure determination, and the failure control unit 42 performs a failure control in accordance with the failure state in that case. .

FIG. 3 shows an example of an operation in which the fuel injection valve 13 is controlled by a drive pulse signal. As shown in FIG. 3A, a valve opening drive pulse signal is sent to the valve opening coil 13a. A similar holding drive pulse signal is sent to one holding coil 13b. Fuel injection valve 1
3 is normal, the valve opening drive pulse signal is supplied, as shown in FIG.
Power supply voltage is supplied to a.

FIG. 3 (c) schematically shows the operating states of the fuel injection valve 13 when "normal", "when the holding coil system fails", and "when the valve opening coil system fails". ) To (e) are the lift amounts of the INJ injection valve.

The fuel injection valve 13 is opened immediately after the supply of the valve-opening drive pulse by the electromagnetic force of the valve-opening coil 13a, and the holding drive pulse signal is supplied.
b, a power supply voltage is supplied to the fuel injection valve 13. The fuel injection valve 13 is kept open by the electromagnetic force of the holding coil 13b.
The electromagnetic force b disappears, and the fuel injection valve 13 is closed by a spring (not shown) built in the fuel injection valve 13 as shown in FIG.

In the operation control of the fuel injection valve 13,
When a failure occurs in the holding coil control system, the fuel injection valve 13 is opened by the valve opening drive pulse signal. Since the holding drive pulse signal cannot be accurately supplied to the fuel injection valve 13b, the fuel injection valve 13 is not given a force for holding the valve open state.
3 cannot be kept open. As a result, as shown in FIG. 3D, the fuel injection valve 13 closes immediately after the supply of the valve opening pulse is interrupted, regardless of the holding pulse signal time.

On the other hand, when a failure occurs in the valve-opening coil control system, the valve-opening drive pulse signal is accurately supplied to the valve-opening coil 13a even though the valve-opening drive pulse signal is supplied. Can not. Therefore, the fuel injection valve 13 is driven only by the holding drive pulse signal. In this case, since driving by the valve opening coil 13a is not performed,
As shown in FIG. 3E, the valve opening force of the fuel injection valve 13 is weaker than normal, and the valve opening operation is delayed.

FIG. 4 shows an example of the fuel injection characteristics of the fuel injection valve 13. When both the valve-opening drive pulse signal and the holding drive pulse signal are supplied to the fuel injection valve 13, the fuel injection characteristic of the fuel injection valve 13 is the normal injection characteristic (A) in FIG. The fuel injection valve 13 when the holding drive pulse signal is not supplied to the valve 13 and only the valve opening drive pulse signal is supplied (the same operating state as the holding coil system failure)
Is the characteristic (B) of only the valve-opening drive pulse in FIG. 4. In this case, the fuel injection valve 13 maintains the open state of the fuel injection valve 13 as described with reference to FIG. Therefore, the fuel injection flow rate cannot be more than the predetermined flow rate regardless of the holding pulse width. Here, the mechanism that cannot inject more than a predetermined amount is as described with reference to FIG. 3 and will not be described in detail here.

Next, when only the holding drive pulse signal is supplied to the fuel injection valve 13 without supplying the valve opening drive pulse signal (the same operating state as the valve opening coil system failure), the fuel injection characteristic of the fuel injection valve 13 is as follows. 4 shows the characteristic (C) of only the holding drive pulse. In this case, as described with reference to FIG. 3, the opening force of the fuel injection valve 13 is impaired, , The rise of the fuel injection flow rate (start of fuel injection injection) is delayed. Here, the mechanism for delaying the rising point of the fuel injection has been described with reference to FIG. 3 and will not be described in detail here.

Further, since the valve opening force is small, the rising point of the fuel injection affects the power supply voltage supplied to the fuel injection valve 13 and the pressure (fuel pressure) of the fuel pipe to which the fuel injection valve 13 is attached. receive. This is because the lower the power supply voltage is, the lower the valve opening force of the fuel injection valve 13 is, and the lower the power supply voltage is, the later the fuel injection rising point is delayed. Also, the higher the fuel pressure, the greater the reaction force against the force direction in which the fuel injection valve 13 is about to open, and the higher the fuel pressure, the more the fuel injection rising point is delayed.

FIG. 5 is an example showing the relationship between the fuel injection valve 13 and the exhaust emission of the internal combustion engine 1. When the holding coil system fails, as described with reference to FIGS. 3 and 4, the desired fuel injection flow rate control cannot be performed.
A desired air-fuel ratio (ratio of the air flow rate and the fuel injection flow rate of the internal combustion engine) cannot be controlled, and not only does the exhaust emission of the internal combustion engine 1 deteriorate, but also the operability of the internal combustion engine 1 deteriorates. Similarly, when the valve opening coil system fails, the desired air-fuel ratio control cannot be performed, and the exhaust emission and the operability of the internal combustion engine 1 deteriorate.

FIG. 6 shows an example of the relationship between the current flowing through the valve opening coil 13a and the pulse width of the valve opening coil drive pulse. The current flowing through the valve-opening coil 13a (hereinafter referred to as valve-opening current) has different characteristics depending on the manufacturing variation of the valve-opening coil 13a, the valve-opening coil power supply line, and the state of the battery voltage serving as the power supply for the valve-opening coil 13a. And the valve opening current has a predetermined variation range even in a normal state.

For example, when the resistance of the valve-opening coil, the inductance of the valve-opening coil, or the resistance of the power supply line is smaller than the reference state with respect to the reference central characteristic (dashed line in the figure) of FIG. As shown in FIG. 6, the valve opening current becomes larger than the central characteristic, and has a characteristic like the maximum characteristic line shown in FIG. On the other hand, the valve opening coil resistance, the valve opening coil inductance,
Alternatively, when the resistance of the power supply line is large, the valve opening current becomes smaller than the central characteristic as shown in FIG.
It has characteristics like the minimum characteristic line shown therein.

However, when the valve opening coil control system fails, the valve opening coil current deviates from the range of the current flowing through the valve opening coil 13a, and the valve opening coil current increases (for example, a ground failure of the valve opening coil power supply line). In the case where a failure and other failure patterns in which the valve-opening current becomes large are plural, the description of each failure pattern is omitted here), the valve-opening current indicated by the upper dotted line in FIG. In the event of a major failure, the characteristic becomes higher than that of the line and the valve opening coil current becomes smaller (for example,
In the case where there are a plurality of failure patterns in which the valve-opening coil power supply line is disconnected and other failure patterns in which the valve-opening current is small, the description of each failure pattern is omitted), which is indicated by the lower dotted line in FIG. Opening current: The characteristics are lower than those of the small failure line. Therefore, when detecting a failure of the valve opening coil 13a, it is sufficient to detect a difference between the normal state and the failure state.

FIG. 7 shows an example of the relationship between the valve opening current and the power supply voltage. The relationship between the power supply voltage and the valve opening current is generally known, and the valve opening current is proportional to the power supply voltage supplied to the fuel injection valve 13. Because of this,
Depending on the power supply voltage value, the valve opening current range may be in the normal state even at the time of failure. Therefore, the valve opening coil 1
In order to detect the failure of 3a, based on the power supply voltage,
It is necessary to detect a failure of the valve opening coil 13a. For example, when the power supply voltage is high, it is necessary to increase the threshold value of the valve opening abnormality determination current, and when the power supply voltage is low, it is necessary to lower the threshold value of the abnormality determination current when the power supply voltage is high.

FIG. 8 shows an example of a control flowchart for judging the valve opening current abnormality shown in FIGS. 6 and 7. In step 71, the power supply voltage supplied to the internal combustion engine is input. In step 72, the fuel injection valve 1
3, the valve opening current IPREF supplied to the valve opening coil 13a.
Is detected. In step 73, a valve opening drive pulse width supplied to the valve opening coil 13a of the fuel injection valve 13 is calculated.

At step 74, the threshold value IPMAX (threshold value for the large opening failure) of the valve opening current abnormal value determination and IP
MIN (valve opening current minor failure threshold) is calculated. Here, the threshold value for judging the valve opening current abnormality is as shown in FIGS.
From the valve opening current characteristics shown in the above, the calculation may be performed using at least one or more parameters of the valve opening pulse width and the power supply voltage, or the setting may be performed using a table or a three-dimensional map.

Here, with respect to the method of calculating the threshold values IPMMAX and IPMIN for determining the valve opening current abnormal value, I
Any one or more of PMMAX and IPMIN may be obtained as a one-point constant. When a one-point constant is used, the I
Although the accuracy of failure detection is lower than that of the calculation method of PMMAX and IPMIN, the CPU calculation load of the calculation means (CPU) 26 of the control device 15 of FIG. It can be greatly reduced.

Threshold value IPM for determining abnormal valve opening current value
The calculation method of AX and IPMIN may be selected according to the fuel injection system configuration and the CPU capability of the failure detection calculation device. For example, in the fuel injection system configuration, the IPREF value detected when the valve opening coil is abnormal indicates an extremely different value from the normal IPREF value, so that the correction based on the valve opening coil pulse width or the power supply voltage described above can be performed. If the failure can be sufficiently detected without performing the above operation, the threshold IPMAX or IPMIN for determining the valve opening current abnormal value by a one-point constant that does not require a relatively large calculation load and ROM capacity of the CPU of the failure detection calculation device. An arithmetic method may be used.

In step 75, the valve opening current IPREF input in step 72 and the threshold values IPMAX and IPMI for valve opening current abnormality determination calculated in step 74 are determined.
Compare with N. When the valve opening current value IPREF is equal to or greater than the abnormal current threshold value IPMAX, or when the valve opening current value IPREF is equal to or less than the abnormal current threshold value IPMIN, the NG counter TIME is incremented.

In step 76, the NG counter TI
ME is a preset failure determination count threshold IPNGC
It is determined whether or not NT has been reached. If the NG counter TIME is equal to or greater than the failure determination threshold IPNGCNT, the routine proceeds to step 77 where the valve opening current diagnosis NG is performed.
Judge.

Here, in the failure determination shown in FIG. 8, when a plurality of fuel injection valves 13 are set in the internal combustion engine, it may be determined that the valve opening current is abnormal for each cylinder. ,
The failure may be detected continuously for all cylinders, and any one or more determination methods may be performed. Further, the failure determination counter T
The IME and the failure determination frequency IPNGCNT are different from each other in that the fuel injection frequency executed until the failure detection is not constant depending on the rotation speed (fuel injection cycle) of the internal combustion engine when the detection is performed based on a simple elapsed time. It is desirable to perform the detection and the determination according to each injection or the rotation speed of the internal combustion engine, and it is possible to provide a failure detection device for the fuel injection valve 13 that is more stable than the simple time determination.

FIGS. 9 to 11 show an example of a means for detecting a failure of the valve-opening coil 13 when the drive control means for driving the valve-opening coil 13a is used. FIG. 9 shows an example of a control block for drive control of the valve opening coil 13a. The current detection circuit 15b is a circuit that holds (peak-holds) a current peak value or a value based on the current peak value flowing through the valve opening coil 13a for a predetermined period. The current detection value calculation unit 172 generates the current detection value by the current detection circuit 15b. The detected peak hold output signal of the current flowing through the valve opening coil 13a is calculated.

On the other hand, the pulse width of the valve-opening coil drive pulse which energizes the valve-opening coil 13a is determined by the operating state detecting means
70, the basic valve opening pulse width calculating means 1
At 71, it is calculated as the basic pulse width. Similarly, the valve opening coil current required for the fuel injection valve 13 to open properly is determined by the target valve opening current value calculating means 173 in accordance with the output signal of the operating state detecting means 170 of the internal combustion engine. It is calculated as a valve opening current value.

Next, in the deviation calculating means 174 between the target valve opening current value and the detected current value, the detected current value calculating means 172 is used.
Then, the deviation between the valve opening coil peak current value calculated by the above and the target valve opening coil current value calculated by the target valve opening current value calculation means 173 is calculated. The valve opening pulse width feedback calculating means 175 performs feedback calculation of the valve opening coil drive pulse width based on the current value deviation calculated by the deviation calculating means 174 or a value calculated based on the current value deviation.

Here, in the feedback calculation, for example, when the target valve opening coil current value> the valve opening coil peak current detection value, a correction is made so as to increase the pulse width of the valve opening coil drive pulse, and the valve opening is actually performed. By increasing the current value flowing through the coil, the target valve opening coil current value is set. If the target valve opening coil current value <the valve opening coil peak current detection value, conversely, correction should be made to shorten the valve opening coil drive pulse width.

The output valve opening pulse width calculating means 176 adds the valve opening coil drive pulse calculated by the valve opening pulse width feedback calculating means 175 to the valve opening coil drive basic pulse width calculated by the basic valve opening pulse width calculating means 171. The feedback calculation value is added to calculate the valve opening coil drive output pulse width, and the valve opening coil 13a of the fuel injection valve 13 is energized.

FIG. 10 shows an example of the relationship between the target valve opening coil current value and the abnormal region of the valve opening coil conduction current in the relationship between the valve opening coil drive pulse width and the valve opening coil current. . The solid line in FIG. 10 indicates the target valve opening coil current value. As described in FIG. 9, the valve opening coil drive pulse is usually set so that the current value flowing to the valve opening coil 13a becomes the target current. Feedback controlled. Therefore, in normal times, the relationship between the drive pulse width for driving the valve opening coil 13a and the maximum current value flowing through the valve opening coil 13a is controlled on the line of the target valve opening coil current value in FIG. become.

The dotted line shown above the target current value line in FIG. 10 indicates that the value of the current flowing through the valve opening coil 13a exceeds the target valve opening current value, and the fuel injection valve 1
The valve opening force of No. 3 becomes larger than a predetermined value, whereby a larger amount of fuel is injected with respect to a desired fuel injection amount, whereby the air-fuel ratio becomes rich. In this case, as the difference between the target valve opening current value and the current value flowing through the valve opening coil 13a is larger,
Difference between target air-fuel ratio and actual air-fuel ratio of internal combustion engine (ΔA / F)
(+ 10%, +20 of the dotted line in the figure)
%).

On the other hand, the dotted line shown below the target current value line in FIG. 10 indicates that the value of the current flowing through the valve opening coil 13a is lower than the target valve opening current value. The valve opening force of No. 13 becomes smaller than a predetermined value, whereby the fuel is injected less than a desired fuel injection amount, so that the air-fuel ratio becomes thin (lean). Again,
Similarly, as the difference between the target valve opening current value and the current value flowing through the valve opening coil 13a increases, the difference (ΔA / F) between the target air-fuel ratio of the internal combustion engine and the actual air-fuel ratio also increases toward the thin side (FIG. 10).
(-10% of the dotted line in the middle, -20%).

In FIG. 10, the shaded portions shown in the upper and lower portions indicate that the deviation between the current value flowing through the valve opening coil 13a and the target valve opening current value becomes large, so that the air-fuel ratio controllability of the internal combustion engine is improved. In a region where the air-fuel ratio rich misfire or lean misfire is caused and the valve-opening coil drive control state exists in that region, as shown in FIG. 5, the drivability and the exhaust emission deteriorate. I will invite you. In such a relationship, by detecting a deviation between the current value flowing through the valve opening coil 13a and the target valve opening current value, a malfunction of the valve opening coil drive control system that causes deterioration in operability and exhaust emission of the internal combustion engine. Can be detected.

FIG. 11 is an example of a control flow chart for controlling the failure detection of the valve opening coil control system based on the relationship shown in FIG. In step 191, FIG.
As shown by the target valve opening current value calculation means 173, the target valve opening coil current value TARGETIP to be supplied to the valve opening coil 13a is calculated in accordance with the operation state of the internal combustion engine. In step 192, the value of the current actually flowing through the valve opening coil 13a is detected by the valve opening current detection circuit 15b. In step 193, the valve-opening coil drive pulse width is calculated according to the valve-opening coil basic pulse width and the value calculated by the valve-opening coil pulse width feedback calculation means as shown in FIG.

In step 194, the difference ΔIP between the target valve opening current value and the current value flowing through the valve opening coil is obtained. In step 195, the current value difference ΔIP and the failure determination threshold value I
Compare with PMAX and IPMIN. Here, an example of failure detection has been described based on a difference ΔIP value between a target valve opening current value and a current value flowing through the valve opening coil. However, failure detection is performed based on a difference between another target valve opening current value and a current value flowing through the valve opening coil. As a method of performing this, a failure determination threshold value IPMAX or IPM is set by setting a table corresponding to the target current value TARGETIP.
A similar failure detection result can be obtained by setting IN and comparing the value with the valve opening current IPREF value.

In step 196, it is determined whether or not the state determined in step 195 is equal to or longer than IPNGCNT for a predetermined period. If it is determined that the state is equal to or longer than IPNGCNT in step 197, it is determined in step 197 that the valve opening coil diagnosis is NG. I do.

As described above, as a method of detecting a current value flowing through the valve opening coil 13a and detecting a failure of the valve opening coil 13a, means for detecting a failure from the electrical characteristics of the valve opening coil 13a shown in FIGS. The means for detecting a failure from the operability and exhaust performance requirements of the internal combustion engine shown in FIGS. 9 to 11 has been described, but any of them can obtain the same effect of detecting a failure of the valve opening coil 13a.

FIG. 12 shows an example of the electrical characteristics of the fuel injection valve 13. The pulse signal shown in FIG.
A drive pulse signal for operating the fuel injection valve 13 for a predetermined period.
3 is supplied with a power supply voltage. The normal and fault signals shown in the middle and lower parts of FIG.
3 schematically shows a voltage signal between a driving circuit 3 and a driving circuit for driving the fuel injection valve 13. During the period in which the drive pulse signal is not supplied, the coil in the fuel injection valve 13 is not energized. Therefore, the voltage has the same voltage value as the power supply voltage. Since the coil in the injection valve 13 is energized, the voltage value becomes ≒ 0V. Fuel injection valve (including coil and connection inside fuel injection valve)
13 is in the normal state, the energization of the pulse signal →
Immediately after the interruption, a back electromotive (current return) occurs due to the characteristics of the coil. Here, the principle of occurrence of the back electromotive force when the coil is energized and then cut off is generally well known, and will not be specifically described here. On the other hand, if the fuel injection valve (including the coil and connection in the fuel injection valve) 13 is disconnected for some reason, the back electromotive does not occur.

FIG. 13 shows an example of a method for detecting a failure of the fuel injection valve 13 using the principle shown in FIG. As shown in FIG. 12, when the fuel injection valve (including the coil and connection in the fuel injection valve) 13 breaks, no back electromotive occurs when the fuel injection valve drive pulse is cut off. The occurrence of back electromotive is detected and the fuel injection valve 13 is detected.
This is an example of detecting a failure of the device.

When a back electromotive occurs after the fuel injection valve driving pulse is cut off, the diagnostic circuit output signal in FIG. 13 generates a one-shot signal for a predetermined period from the fuel injection valve diagnostic circuit. If not, no one-shot signal is generated. By detecting the occurrence of the one-shot signal, the failure of the fuel injection valve 13 can be detected.

Here, the method of determining the failure of the fuel injection valve 13 may be that the failure of the fuel injection valve 13 is determined when the one-shot signal has not been generated for a predetermined period. In the present embodiment, the fuel injection valve 13 has two coils (the valve opening coil 1).
3a and the holding coil 13b).
The fault diagnosis may be performed for at least one coil. In FIG. 13, a method has been described in which the presence / absence of the back electromotive signal is detected, a one-shot signal is generated, and the failure of the fuel injection valve 13 is detected based on the presence / absence of the one-shot signal. The presence / absence of occurrence of an electromotive signal may be detected.

Here, the method of determining the failure of the fuel injection valve 13 will be described with reference to FIG.
As shown in the above, the counter for the presence or absence of the one-shot signal may be detected and determined for each fuel injection or according to the rotation speed of the internal combustion engine. Here, the description of the method of determining the failure has been described in steps 75 and 76 in FIG.

FIG. 14 is an example of a control flow chart of the fuel injection when NG is judged in the diagnosis of the valve opening coil 13a of the fuel injection valve 13 of the present embodiment. In step 91, NG determination is performed in the diagnosis of the valve opening coil 13a of the fuel injection valve 13. When the NG determination is made, in step 92, the supply of the valve opening coil drive pulse for all cylinders is stopped. Let it.

Next, in step 93, the holding coil drive pulse width is corrected. As a result, the same fuel injection flow rate can be ensured only by the holding coil of the fuel injection valve 13 without driving the valve opening coil of the fuel injection valve 13. In step 94, limit correction is performed so that the minimum value of the drive pulse width for driving the fuel injection valve 13 is larger than that in the normal state. By increasing the minimum value, a fuel injection amount equal to or more than a predetermined value can be secured even when the valve opening coil fails, and even when the valve opening coil fails, the internal combustion engine does not stop (stall) and the operation is continued. It becomes possible.

FIG. 15 is an example of a control flowchart of the fuel injection when the NG determination is made in the valve opening coil diagnosis of the fuel injection valve 13 of the present embodiment. Here, a control method different from the control at the time of failure in FIG. 14 will be described. In the step 101, when an NG determination is made in the valve opening coil diagnosis of the fuel injection valve 13 (step 9 in FIG. 14)
(Same as 1), in step 102, the fuel cut of the cylinder determined to be faulty is performed, and the operation of the internal combustion engine with the normal cylinder is performed. Also in this control method, fail-safe control at the time of failure may be performed.

FIG. 16 is an example of a control flowchart of the fuel pressure when the NG determination is made in the valve opening coil diagnosis of the fuel injection valve 13 of the present embodiment. In step 111,
If NG is determined in the valve opening coil diagnosis of the fuel injection valve 13 (same as step 91 in FIG. 14), in step 112, the pressure in the fuel pipe of the internal combustion engine, that is, the fuel pressure is given an upper limit to INJNGFP. By giving the upper limit to the fuel pressure, the decrease in the valve opening force of the fuel injection valve 13 due to the failure of the valve opening coil 13a of the fuel injection valve 13 is compensated for, and the fuel injection can be reliably performed. Here, the fact that the fuel injection performance of the fuel injection valve 13 is stabilized by lowering the fuel pressure when the valve opening coil 13a fails has been described with reference to FIG. 4 and will not be described in detail here.

FIG. 17 is an example of a control flowchart of the fuel injection when the NG determination is made in the diagnosis of the holding coil of the fuel injection valve 13 of the present embodiment. Step 12
If the NG determination is made in the diagnosis of the holding coil 13b of the fuel injection valve 13 in step 1, fuel is cut off in the cylinder determined to have a failure in step 122, and the internal combustion engine is operated with a normal cylinder.

FIG. 18 is an example of a control flow chart of the fuel injection when an NG determination is made in the diagnosis of the valve opening coil 13a or the holding coil 13b of the fuel injection valve 13 of the present embodiment. In step 131, the fuel injection valve 13
If an NG determination is made in the diagnosis of either the valve opening coil 13a or the holding coil 13b in step 132,
When it is determined that the rotation speed during the internal combustion period is equal to or more than the predetermined value (INJNGNE), the fuel cut of all cylinders is performed.

FIG. 19 is an example of a control flowchart of the air-fuel ratio feedback control of the internal combustion engine when the NG determination is made in the diagnosis of the valve opening coil 13a or the holding coil 13b of the fuel injection valve 13 of the present embodiment. Step 1
If it is determined in step 61 that the NG determination is made in the diagnosis of either the valve opening coil 13a or the holding coil 13b of the fuel injection valve 13 (same as step 131 in FIG. 18), in step 162, the malfunctioning cylinder is determined. Cut fuel. Next, at step 163, the air-fuel ratio feedback control of the internal combustion engine is stopped. This is because, when the fuel is cut by the failure diagnosis, combustion is not performed in the cylinder in which the fuel is cut, so that the air-fuel ratio sensor 20 provided in the exhaust pipe 28 of the internal combustion engine is affected, and the fuel is cut off. If the air-fuel ratio feedback control is performed even during the cut control, the air-fuel ratio control of the internal combustion engine becomes inaccurate. Therefore, by not performing the air-fuel ratio feedback control, it is possible to avoid an inaccurate state of the air-fuel ratio control.

Although some embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and does not depart from the spirit of the present invention described in the claims. Various changes can be made in the design.

[0077]

As can be understood from the above description, the fuel injection device for an internal combustion engine according to the present invention includes a failure diagnosis means for the excitation coil of the fuel injection valve in the control device, and the diagnosis result of the failure diagnosis means is provided. By performing air-fuel ratio control based on
Even when the fuel injection valve fails, a stable operation state of the internal combustion engine can be ensured, and operability and exhaust performance can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing an overall control system configuration of a direct injection internal combustion engine including a fuel injection device for an internal combustion engine according to an embodiment of the present invention.

FIG. 2 is a control block diagram of a failure diagnosis unit of an exciting coil of a fuel injection valve in the fuel injection device for an internal combustion engine of FIG. 1;

FIG. 3 is a diagram illustrating the operation of a two-coil fuel injection valve.

FIG. 4 is a fuel injection characteristic diagram of a two-coil fuel injector.

FIG. 5 is a diagram showing fuel injection characteristics and exhaust performance when the fuel injection device is normal and when it fails.

FIG. 6 is a current characteristic diagram of a valve opening coil of a fuel injection valve.

FIG. 7 is a characteristic diagram showing a relationship between a valve opening coil current and a voltage of the fuel injection valve.

FIG. 8 is a control flowchart of a failure diagnosing means of an exciting coil of the fuel injection valve of FIG. 2;

FIG. 9 is another control block diagram of driving the valve-opening coil of the fuel injection valve in the fuel injection device for the internal combustion engine of FIG. 1;

10 shows the relationship between the target valve opening coil current value and the abnormal region of the valve opening coil conduction current in the relationship between the valve opening coil drive pulse width and the valve opening coil current for driving the valve opening coil of the fuel injection valve of FIG. 9; FIG.

FIG. 11 is a control flowchart of driving a valve opening coil of the fuel injection valve in FIG. 9;

FIG. 12 is an electric characteristic diagram of the fuel injection valve of FIG. 1;

FIG. 13 is a diagram showing an example of a failure diagnosis of the fuel injection valve of FIG. 1;

FIG. 14 is a control flowchart at the time of failure of a holding coil in the failure diagnosis of the fuel injection valve of FIG. 1;

FIG. 15 is a control flowchart at the time of failure of a valve opening coil in failure diagnosis of the fuel injection valve of FIG. 1;

FIG. 16 is a control flowchart of a fuel pressure at the time of failure of a valve opening coil in failure diagnosis of the fuel injection valve of FIG. 1;

FIG. 17 is a control flowchart at the time of failure of a holding coil in the failure diagnosis of the fuel injection valve of FIG. 1;

FIG. 18 is a control flowchart at the time of failure in the failure diagnosis of the fuel injection valve of FIG. 1;

FIG. 19 is a diagram illustrating an example of a failure diagnosis method for a fuel injection valve.

[Explanation of symbols]

13: fuel injection valve, 13a: valve opening coil, 13b: holding coil, 15: control unit (control device), 1
5A: Failure diagnosis means, 26: Calculation means (CPU), 15
a: disconnection diagnosis circuit, 15b: valve opening coil current detection circuit,
15c: Holding coil disconnection diagnosis circuit, 40: Failure detection unit,
40a: valve opening coil disconnection diagnosis means, 40b: valve opening coil abnormal current diagnosis means, 40c: holding coil disconnection diagnosis means,
41: fuel injection valve failure calculation unit, 42: fuel injection valve failure control unit

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Minoru Okubo, Inventor Minami, Hitachinaka-shi, Ibaraki Prefecture 2520 Takaba F-term in the Automotive Equipment Group of Hitachi, Ltd. (Reference) 3G066 AA02 AB02 BA31 BA33 BA51 BA61 CC06U CE25 CE29 DA02 DC04 DC05 DC11 DC14 DC24 3G301 HA01 HA04 JB02 JB08 JB09 LB02 LB04 LC10 MA11 MA24 NA08 NC02 ND15 NE06 NE17 NE19 PA01Z PA11Z PD02Z PE03Z PE08Z PF03Z PG02Z

Claims (17)

[Claims] 1. A fuel injection device for an internal combustion engine comprising: a fuel injection valve having a valve opening coil and a holding coil; and a control device, wherein the control device detects a peak current value flowing through the valve opening coil. Means for determining whether the peak current value or the value based on the peak current value is equal to or greater than a preset failure determination threshold, or is equal to or less than another set failure determination threshold. Means for diagnosing a failure, wherein the failure diagnosis means diagnoses a failure when the peak current value or a value based on the peak current value continues the state for a predetermined failure determination period or more. A fuel injection device for an internal combustion engine. 2. The fuel injection device for an internal combustion engine according to claim 1, wherein the control device includes a drive circuit that controls energization of the two coils that open and close the fuel injection valve. . 3. A fuel injection device for an internal combustion engine, comprising: a fuel injection valve having a valve opening coil and a holding coil; and a control device, wherein the control device detects a peak current value flowing through the valve opening coil. Means for detecting the operating state of the internal combustion engine, means for calculating a basic pulse width for driving the valve opening coil according to the operating state of the internal combustion engine, and calculating a target valve opening current value Means, and means for feedback-controlling the valve-opening coil drive pulse width so that the peak current value becomes the target valve-opening current value. The control device includes the target valve-opening current calculation value and the peak value. Calculating a difference from the current value, a state in which the current value difference or a value based on the current value difference is equal to or greater than a predetermined failure determination threshold,
Or, when the state is equal to or less than another preset failure determination threshold value, the apparatus further comprises means for diagnosing a failure of the fuel injection valve by determining that the valve opening coil is abnormal, wherein the failure diagnosis means comprises the peak current A fuel injection device for an internal combustion engine, characterized in that when a value or a value based on the peak current value continues the state for a predetermined failure determination period or longer, a failure is diagnosed. 4. The internal combustion engine according to claim 1, wherein the failure determination period is calculated for each fuel injection or for each rotation speed of the internal combustion engine. Fuel injection device. 5. The failure determination threshold value is calculated using a parameter including at least one of a valve-opening coil drive pulse width and a power supply voltage. A fuel injection device for an internal combustion engine according to claim 1. 6. The method according to claim 5, wherein one of the failure determination thresholds is set as a fixed value.
3. A fuel injection device for an internal combustion engine according to claim 1. 7. A fuel injection device for an internal combustion engine, comprising: a fuel injection valve having a valve opening coil and a holding coil; and a control device, wherein the control device is generated when power supply to the valve opening coil is cut off. The presence or absence of a current return (back-emergence) is detected, and when the state in which the current return does not occur continues for a predetermined period, it is determined that the valve-opening coil is disconnected or short-circuited. A fuel injection device for an internal combustion engine, which determines a functional failure of the fuel injection valve. 8. A fuel injection device for an internal combustion engine, comprising: a fuel injection valve having a valve opening coil and a holding coil; and a control device, wherein the control device generates a current generated when power supply to the holding coil is cut off. The presence or absence of a return (back electromotive force) is detected, and when the state in which the current return has not occurred has continued for a predetermined period, the holding coil is determined to be disconnected or short-circuited, so that the holding coil is determined to be abnormal and the fuel A fuel injection device for an internal combustion engine, which determines a malfunction of an injection valve. 9. The internal combustion engine according to claim 7, wherein the failure determination period in a state where no current return occurs is calculated for each fuel injection or for each rotation speed of the internal combustion engine. Engine fuel injector diagnostic device. 10. The control device, when it is determined that a malfunction of the fuel injection valve due to an abnormality of the valve opening coil is performed, cuts off supply of a valve opening coil drive pulse to all cylinders, and uses only a holding coil to supply fuel. The fuel injection device for an internal combustion engine according to any one of claims 2 to 9, wherein injection control is performed. 11. The fuel injection device for an internal combustion engine according to claim 10, wherein when the fuel injection control is performed only by the holding coil, the correction is performed so that the holding coil drive pulse width becomes long. 12. The control device includes means for variably controlling a pressure (fuel pressure) in a fuel pipe supplied to the internal combustion engine, and when the fuel injection control is performed only by the holding coil, the control device includes: The fuel injection device for an internal combustion engine according to claim 10, wherein the fuel pressure is controlled such that a pressure (fuel pressure) in the supplied fuel pipe is equal to or less than a predetermined value. 13. When a malfunction of the fuel injection valve is determined due to an abnormality of the valve opening coil, the fuel of the cylinder corresponding to the failure determination is cut (the supply of the valve opening coil drive pulse and the holding coil drive pulse is stopped). The fuel injection device for an internal combustion engine according to any one of claims 2 to 7, wherein the fuel injection device performs cutting. 14. When a functional failure of the fuel injection valve is determined due to an abnormality of the holding coil, the fuel of the cylinder corresponding to the failure determination is cut (the supply of the valve opening coil drive pulse and the holding coil drive pulse is cut off). The fuel injection device for an internal combustion engine according to claim 8, wherein 15. When it is determined that a malfunction of the fuel injection valve has occurred, the fuel of all the cylinders is cut off when the internal combustion engine rotation speed becomes equal to or higher than a predetermined rotation (a valve opening coil driving pulse and a holding coil driving pulse). The fuel injection device for an internal combustion engine according to any one of claims 2 to 12, wherein the supply is cut. 16. The fuel injection device for an internal combustion engine according to claim 13, wherein the air-fuel ratio feedback control is not performed when the malfunction of the fuel injection valve is determined. 17. The valve-opening coil is a coil having a large time change rate of a magnetomotive force given by a product of the number of turns of the coil and a current value flowing through the valve-opening coil, and the holding coil is
The fuel injection device for an internal combustion engine according to any one of claims 1 to 16, wherein the coil has a smaller time change rate of the magnetomotive force than the valve opening coil.