JPH10238391A - Fuel injection device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stop injection of fuel in a short time during the occurrence of abnormality of a fuel injection valve. SOLUTION: High pressure fuel is fed from a high pressure fuel injection pump 5 to a common rail 3 and fuel is fed from the common rail to each fuel injection valve 1. A control circuit (ECU) 20 decides the occurrence of abnormality of some fuel injection valve based on a common rail fuel pressure detected by the fuel pressure sensor 31. During detection of abnormality, the feed of fuel from the high pressure fuel pump to the common rail is stopped and infection of fuel from a normal fuel injection valve is continued. By this constitution, since fuel stored in the common rail is injected to each cylinder and discharged from the common rail, the pressure of the common rail is lowered in a short time and injection of fuel from the fuel injection valve to which abnormality occurs is completed in a short time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a fuel injection device for an internal combustion engine.

[0002]

2. Description of the Related Art Fuel is supplied from a high-pressure fuel pump to a common accumulator (common rail), and a fuel injection valve for each cylinder is connected to the accumulator to supply high-pressure fuel stored in the accumulator to each cylinder of the internal combustion engine. There is known a so-called common rail type fuel injection device for injecting fuel. In addition, a common rail type fuel injection device includes a means for preventing an engine from being adversely affected when one of the fuel injection valves causes an abnormal injection by a valve-open stick or the like. There is one described in Japanese Unexamined Patent Publication No. Hei.

When the fuel injection valve causes abnormal injection by a valve-opening stick or the like, a large amount of fuel is supplied into the cylinder from the abnormal fuel injection valve, and the combustion of the fuel causes an abnormal cylinder pressure. May rise. When such an abnormal increase in the in-cylinder pressure occurs, the durability of each part of the engine decreases, and in extreme cases, the engine may be damaged. The device disclosed in Japanese Patent Application Laid-Open No. H2-112643 is provided with a plurality of accumulators, a fuel injection valve connected to each accumulator, and a plurality of fuel pumps for supplying fuel to the respective accumulators. When the abnormal injection of the valve is detected, the fuel supply from the fuel pump to the accumulator to which the abnormal fuel injection valve is connected is stopped.

As a result, fuel is no longer supplied to the accumulator connected to the failed fuel injection valve, and after fuel remaining in the accumulator is injected, fuel is injected from the failed fuel injector. Stops. For this reason, according to the above device, the abnormal injection is completed in a relatively short time, and the period during which the engine is exposed to the high in-cylinder pressure due to abnormal combustion is shortened. Can be reduced.

[0005]

However, in the apparatus disclosed in Japanese Patent Application Laid-Open No. 2-112463, the fuel supply to the common rail is stopped, but the fuel stored in the common rail is continuously injected from the fuel injection valve. Until the fuel pressure in the common rail is sufficiently reduced, fuel is injected from the failed fuel injection valve.

[0006] The amount of fuel stored in the common rail increases according to the fuel pressure in the common rail. Moreover, in the common rail type fuel injection device, the fuel pressure in the common rail is generally set high to perform high-pressure fuel injection, and a fuel injection device in which the fuel pressure in the common rail is set to about 150 MPa is also used. Assuming that the fuel pressure in the common rail is P, assuming that the bulk modulus K is constant, the value Q obtained by converting the amount of fuel stored in the common rail having the inner volume V into a value under atmospheric pressure is Q = P × V / K. Therefore, in the common rail type fuel injection device that performs high pressure injection as described above, a large amount of fuel is stored in the common rail even when the common rail internal volume is small. For this reason, Japanese Unexamined Patent Application Publication No.
As in the device disclosed in Japanese Patent Publication No. 3 (1993), simply stopping the fuel supply to the common rail may require a long time until a large amount of fuel stored in the common rail is discharged by the fuel injection and the pressure in the common rail decreases. is there. Moreover,
During this time, the fuel injection from the fuel injection valve in which the abnormality has occurred is continued, so that the period during which the engine is exposed to the abnormal in-cylinder pressure is not necessarily shortened, which causes problems such as a decrease in engine durability.

To prevent this, it is conceivable to stop the fuel supply to the common rail and stop the fuel injection from the abnormal fuel injector. However, it is generally difficult to stop fuel injection from a fuel injection valve in which abnormal injection has occurred. For example, in the case of abnormal injection in which energization of the fuel injection valve cannot be stopped due to an abnormality in the control circuit or a short circuit in the electric circuit, the fuel injection cannot be stopped by electrical control. Also,
It is difficult to stop the fuel injection by the electric control even in an abnormality where the valve opening state of the fuel injection is mechanically fixed by a foreign object biting or a stick or the like.

SUMMARY OF THE INVENTION In view of the above problems, the present invention stops the fuel injection from a fuel injection valve having an abnormality in a short time when the abnormality occurs in the fuel injection valve, thereby shortening the period of occurrence of the abnormal in-cylinder pressure. It is an object of the present invention to provide a fuel injection device capable of performing the following.

[0009]

According to the first aspect of the present invention, there is provided a fuel pump for increasing the pressure of fuel of an internal combustion engine, a pressure accumulating chamber for storing high-pressure fuel supplied from the fuel pump, and a pressure accumulating chamber. A plurality of fuel injection valves connected to inject the fuel in the accumulator into the internal combustion engine, abnormality detection means for detecting abnormality of the fuel injection valves, and abnormality of any one of the fuel injection valves detected by the abnormality detection means Means for stopping supply of fuel from the fuel pump to the accumulator, and discharging the fuel in the accumulator to the outside of the accumulator when the abnormality of the fuel injection valve is detected by the abnormality detector. A fuel injection device for an internal combustion engine, comprising:

In other words, according to the first aspect of the present invention, when an abnormality occurs in the fuel injection valve, the pressure reducing means does not wait for the fuel pressure to decrease only by the fuel injection from the abnormal fuel injection valve. This positively lowers the fuel pressure in the common rail. As a result, the fuel pressure in the common rail decreases in a short time, and the fuel injection from the fuel injection valve in which the abnormality has occurred stops in a short time.

According to the second aspect of the present invention, the pressure reducing means lowers the fuel pressure in the accumulator by performing fuel injection from all the fuel injection valves including the fuel injection valve in which the abnormality is detected. A fuel injection device according to claim 1 is provided. That is, in the invention of claim 2, the pressure reducing means performs fuel injection from all the fuel injection valves including the fuel injection valve in which the abnormality has occurred. As a result, the fuel stored in the common rail is dispersed and injected into each cylinder, and the fuel pressure in the common rail decreases in a short time. Therefore, fuel injection is stopped in a short time without supplying a large amount of fuel only to the cylinder of the fuel injection valve in which the abnormality has occurred.

According to the third aspect of the present invention, the pressure reducing means further compares the amount of fuel injected from a fuel injection valve other than the fuel injection valve in which the abnormality was detected before the abnormality was detected. The fuel injection device according to claim 2, further comprising an abnormal time increase means for increasing the fuel injection amount. That is, claim 3
According to the second aspect of the present invention, the pressure reducing means of the second aspect further includes an abnormal amount increasing means for increasing a fuel injection amount from a fuel injection valve other than the fuel injection valve in which the abnormality has occurred. As a result, the discharge speed of the fuel in the common rail is increased, and the fuel pressure in the common rail is reduced in a shorter time, so that the fuel injection from the fuel injection valve in which the abnormality has occurred is stopped.

According to the fourth aspect of the present invention, the pressure reducing means further includes an abnormal time retarding means for delaying a fuel injection timing from at least a fuel injection valve other than the fuel injection valve in which the abnormality is detected. A fuel injection device according to any one of claims 2 and 3 is provided. That is, in the invention of claim 4, the pressure reducing means of claim 2 or 3 further comprises an abnormal time delay means for delaying the fuel injection timing of at least the fuel injection valve other than the fuel injection valve in which the abnormality has occurred. ing. As a result, in the cylinders of the fuel injection valves other than the fuel injection valve in which the abnormality has occurred, it is possible to prevent the increase in the in-cylinder pressure while greatly increasing the fuel injection amount. Therefore, the fuel injection amount from the normal fuel injection valve can be further increased, so that the fuel injection can be stopped in a shorter time.

[0014]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a diagram showing a schematic configuration of an embodiment when the present invention is applied to an automobile diesel engine. In FIG. 1, reference numeral 1 denotes a fuel injection valve for directly injecting fuel into each cylinder of an internal combustion engine 10 (a four-cylinder diesel engine in this embodiment), and reference numeral 3 denotes a common accumulator (common rail) to which each fuel injection valve 1 is connected. ). The common rail 3 has a function of storing pressurized fuel supplied from a high-pressure fuel injection pump 5 described later and distributing the pressurized fuel to each fuel injection valve 1.

In FIG. 1, reference numeral 7 denotes a fuel tank for storing fuel (light oil in this embodiment) of the engine 10, and reference numeral 9 denotes a low-pressure feed pump for supplying fuel to a high-pressure fuel pump. During operation of the engine, the fuel in the tank 7 is boosted to a constant pressure by the feed pump 9 and supplied to the high-pressure fuel injection pump 5. The fuel discharged from the high-pressure fuel injection pump 5 is supplied to the common rail 3 through the check valve 15 and the high-pressure pipe 17, and further from the common rail 3 to each cylinder of the internal combustion engine via each fuel injection valve 1. It is injected.
In FIG. 1, reference numeral 19 denotes a return fuel pipe for returning leaked fuel from each fuel injection valve 1 to the fuel tank 7.

In FIG. 1, reference numeral 20 denotes an engine control circuit (ECU) for controlling the engine. The ECU 20 is configured as a digital computer having a known configuration in which a read-only memory (ROM), a random access memory (RAM), a microprocessor (CPU), and an input / output port are connected by a bidirectional bus. The ECU 20 controls the opening and closing operation of the suction valve 5a of the high-pressure fuel injection pump 5 to control the fuel oil pressure in the common rail 3 in accordance with the engine load, the number of revolutions, and the like, as will be described later. Further, the ECU 20 controls the valve opening time of the fuel injection valve 1 to perform a fuel injection amount control for controlling an amount of fuel injected into the cylinder. That is, in the present embodiment, the injection rate of the fuel injector 1 is controlled by the common rail fuel pressure, and the fuel injection amount is controlled by the common rail fuel pressure and the valve opening time of the fuel injector 1.

In this embodiment, as described later, E
The CU 20 functions as abnormality detecting means for detecting abnormalities such as abnormal injection of the fuel injection valve 1 and means for stopping fuel supply in the common rail in the event of an abnormality, and as pressure reducing means for lowering fuel pressure in the common rail. Plays the function of. For the above control, an input port of the ECU 20 is provided with a fuel pressure sensor 31 provided on the common rail 3.
, A voltage signal corresponding to the fuel pressure in the common rail 3 is input through an AD converter 34, and an accelerator opening sensor 35 provided on an engine accelerator pedal (not shown).
, A signal corresponding to the operation amount (depressed amount) of the accelerator pedal is input via the AD converter 34. Furthermore,
An input port of the ECU 20 receives a crank rotation angle pulse signal generated according to the crank rotation angle from a crank angle sensor 37 provided on a camshaft (not shown) of the engine.

An output port of the ECU 20 is connected to the fuel injection valves 1 via a drive circuit 40 to control the operation of each of the fuel injection valves 1. Is connected to a solenoid actuator for controlling the opening and closing of the suction valve 5a, and controls the amount of fuel pumped from the pump 5 to the common rail 3. In the present embodiment, the high-pressure fuel injection pump 5 is in the form of a piston pump having two cylinders. The piston in each cylinder of the pump 5 is pressed by a cam formed on the piston drive shaft and reciprocates in the cylinder. In addition, a suction port of each cylinder is provided with a suction valve 5a which is opened and closed by a solenoid actuator. In the present embodiment, the piston drive shaft is driven by a crankshaft (not shown) of the engine 10 and rotates at a half speed of the crankshaft in synchronization with the crankshaft. Further, a cam having two lift portions is formed on a portion of the piston drive shaft of the pump 5 that engages with each piston. The piston of the pump 5 rotates the fuel in synchronization with the stroke of each cylinder of the engine 10. Is discharged. That is, in this embodiment, since a four-cylinder diesel engine is used, the two cylinders of the pump 5
The fuel is pumped to the common rail 3 twice in synchronization with the stroke of the cylinder of the engine (for example, for each exhaust stroke of each cylinder) twice during the rotation of 20 degrees.

Further, the ECU 20 controls the discharge flow rate of the fuel oil from the pump by changing the closing timing of the suction valve 5a in the ascent (pressure feeding) stroke of the piston of each cylinder of the pump. That is, the ECU 20 stops energizing the solenoid actuator during the piston descending stroke (suction stroke) of each cylinder and for a predetermined period after the start of the piston ascent stroke (discharge stroke), and maintains the intake valve 5a in the open state. . Thus, in each cylinder, even if the piston enters the discharge stroke, the fuel in the cylinder flows backward from the suction valve 5a to the tank while the suction valve 5a is open, and the fuel pressure in the cylinder does not increase. Then, after the above period elapses, the ECU
Reference numeral 20 energizes the solenoid actuator of the suction valve 5a to close the suction valve 5a. As a result, the pressure in the cylinder rises with the rise of the pump piston, and when the pressure in the cylinder becomes higher than the pressure in the common rail 3, the check valve 15 of each cylinder opens, and the high-pressure fuel oil in the cylinder is supplied to the high-pressure pipe. It is fed to the common rail 3 via the line 17. Once the intake valve 5a is closed, it is pushed by the fuel pressure while the fuel oil pressure in the cylinder is high, and is kept closed.
Accordingly, the amount of fuel pressure fed to the common rail 3 is determined by the closing start timing of the suction valve 5a of the pump 5. For this reason ECU
Reference numeral 20 controls the amount of fuel to be pumped to the common rail 3 by changing the effective stroke of the piston of the pump 5 by adjusting the closing timing of the suction valve 5a of each cylinder of the pump 5 (timing of energizing the solenoid actuator). ing.

In this embodiment, the ECU 20 sets the target common rail fuel pressure based on the relationship stored in the ROM in advance according to the engine load (accelerator opening) and the number of revolutions, and sets the common rail fuel pressure detected by the fuel pressure sensor 31. The discharge amount of the pump 5 is controlled so that the pressure becomes the set target common rail fuel pressure. The ECU 20 also stores a ROM in advance according to the engine load (accelerator opening) and the number of revolutions.
The fuel injection valve 1 controls the valve opening time (fuel injection time) and the injection timing based on the relationship stored in (1).

That is, in this embodiment, the common rail 3
By changing the fuel pressure according to the engine operating conditions, the injection rate of the fuel injector 1 is adjusted according to the operating conditions,
By changing the fuel pressure and the fuel injection time, the fuel injection amount is adjusted according to the operating conditions. For this reason, in the common rail type fuel injection device as in the present embodiment, the fuel pressure in the common rail is in a wide range (for example, 10 in the present embodiment) according to the operating conditions (load, rotation speed) of the engine.
(In the range of from about 1 MPa to about 150 MPa), and may become extremely high during operation.

Next, the operation of reducing the common rail pressure when the fuel injection valve is abnormal in this embodiment will be described. In the present embodiment, when the ECU 20 detects that abnormal injection has occurred due to the valve-open stick of the fuel injection valve or the like, the ECU 20 stops energizing the solenoid of the suction valve 5a of the fuel pump 5 to open the suction valve 5a. . Thereby, the fuel pump 5
The fuel supply to the common rail 3 is stopped. In this state, although the flow of new fuel into the common rail 3 is stopped, a large amount of fuel is stored in the common rail 3 when the pressure in the common rail 3 is high. Therefore, if the engine is stopped when the abnormal injection of the fuel injection valve is detected, the fuel injection from the normal fuel injection valve stops, but the fuel injection from the fuel injection valve that caused the abnormal injection as described above stops. Therefore, a large amount of fuel in the common rail 3 is discharged from the failed fuel injection valve into the cylinder, and combustion continues in this cylinder. Therefore, abnormal combustion occurs for a long time in the cylinder of the fuel injection valve in which the abnormality has occurred, and the in-cylinder pressure increases.

Therefore, in the present embodiment, even when an abnormal injection of the fuel injection valve is detected, the fuel injection from the normal fuel injection valve is continued without stopping, and all the fuel injection valves including the abnormal fuel injection valve are detected. The fuel injection from is performed. This allows
The stored fuel is quickly discharged from the common rail, and the fuel pressure in the common rail decreases in a short time. Therefore, in the present embodiment, the fuel injection from the fuel injection valve in which the abnormality has occurred ends in a short time, and the increase in the in-cylinder pressure due to the abnormal combustion ends in a short time.

FIG. 2 is a flowchart showing the above-described abnormal-time control operation. This control operation is performed as a routine executed by the ECU 20 at regular intervals. When the routine is started in FIG. 2, it is determined in step 201 whether any of the fuel injection valves is abnormal. In the present embodiment, the presence / absence of an abnormality of the fuel injection valve is detected by an abnormality detection routine (not shown) separately executed by the ECU 20 based on, for example, a common rail pressure drop width before and after fuel injection. More specifically, the ECU 20
The fuel pressure sensor 31 detects the common rail pressure before and after the start of fuel injection to each fuel injection valve, and calculates the fuel pressure drop in the common rail due to fuel injection from each fuel injection valve. If the pressure drop width at the time of fuel injection from a specific fuel injection valve is larger than a predetermined value at the time of fuel injection from another fuel injection valve, an abnormality such as a valve-open stick occurs at this fuel injection valve. Judge that it has occurred.

In the present invention, the method of detecting an abnormality of the fuel injection valve is not limited to the above, and any other method can be used as long as it can detect an abnormality such as abnormal injection of the fuel injection valve. For example, when abnormal fuel injection occurs in a fuel injection valve of a specific cylinder, the combustion pressure in this cylinder increases, and the output torque of only this cylinder increases. For this reason, the rotational speed of the engine crankshaft during the explosion stroke of each cylinder is detected, and if the crankshaft rotation speed during the explosion stroke of a specific cylinder is higher than a predetermined value compared to other cylinders, the fuel of this cylinder is increased. It may be determined that abnormal injection has occurred in the injection valve.

When an abnormal injection occurs in a fuel injection valve of a specific cylinder, the amount of fuel supplied to that cylinder increases as compared with other cylinders. For this reason, in an engine in which an air-fuel ratio sensor that detects the air-fuel ratio of exhaust gas is disposed in the exhaust system, the amount of fuel supplied to each cylinder is directly calculated from the air-fuel ratio of exhaust gas from each cylinder and the exhaust gas flow rate. When this fuel amount is larger than the other cylinders by a predetermined value or more, it may be determined that abnormal injection has occurred in the fuel injection valve of this cylinder.

In FIG. 2, if an abnormality has occurred in the fuel injection valve in step 201, the routine proceeds to step 203, where the energization of the suction valve 5a of the fuel pump 5 is stopped and the intake valve 5a is stopped.
To release. Thereby, the supply of fuel from the fuel pump 5 to the common rail 3 is stopped. After stopping the fuel supply to the common rail 3 as described above, in this routine, the fuel injection from all the fuel injection valves including the fuel injection valve in which the abnormality has occurred is continued. As a result, the fuel stored in the common rail 3 is dispersed and injected into all the cylinders from all the fuel injection valves, and the fuel pressure in the common rail 3 decreases in a short time. For this reason, in this embodiment, it is possible to stop the fuel injection from the fuel injection valve in which the abnormality has occurred in a short time after the abnormality is detected.

It is also possible to connect the common rail 3 to the return pipe 19 via an electromagnetic shutoff valve or the like, and use this electromagnetic shutoff valve as a pressure reducing means. That is, it is possible to discharge the fuel in the common rail to the fuel tank 7 via the return pipe 19 by opening the electromagnetic shut-off valve when an abnormality is detected, and to reduce the pressure in the common rail 3 in a short time. According to the second embodiment, it is not necessary to provide a dedicated electromagnetic shut-off valve for reducing the pressure on the common rail 3, and the fuel pressure in the common rail can be reduced by using another injection valve.

Next, another embodiment of the present invention will be described with reference to FIG. In the embodiment of FIG. 2, the time required for the fuel pressure of the common rail 3 to decrease is shortened by continuing the fuel injection from the normal fuel injection valve when an abnormality occurs. In the present embodiment, not only does the fuel injection from the normal fuel injection valve continue when an abnormality occurs, but at least the amount of fuel injected from the normal fuel injection valve is increased,
Further, the time required for the pressure to decrease is reduced.

As described above, in this embodiment, the ECU 2
0 calculates the fuel injection amount from each fuel injection valve based on the engine load (accelerator opening) and the engine speed, and sets the valve opening time (injection time) of each fuel injection valve so that this fuel injection amount is obtained. ). In the embodiment of FIG. 2, the fuel amount injected from the normal fuel injection valve even after the abnormality is detected is the normal fuel injection amount calculated as described above. On the other hand, in the present embodiment, when an abnormality is detected in one of the fuel injection valves, the amount of fuel injection from normal fuel injection valves other than the fuel injection valve in which the abnormality has occurred is increased. As a result, the amount of fuel discharged from the normal fuel injection valve into each cylinder is larger than in the normal case, so that the fuel pressure in the common rail 3 can be reduced in a shorter time than in the embodiment of FIG. It becomes possible.

When the fuel injection amount from a normal fuel injection valve is increased, the in-cylinder pressure increases even in a normal cylinder due to an increase in combustion pressure, and the output torque increases. In the present embodiment, the increase width of the fuel injection amount from the normal fuel injection valve at the time of abnormality detection is determined so that the output torque and the in-cylinder pressure increase can be in an allowable range. FIG. 3 is a flowchart similar to FIG. 2 illustrating the abnormal-time control operation of the present embodiment. This control operation is performed as a routine executed by the ECU 20 at regular intervals.

When the routine starts in FIG.
In step 301, it is determined whether any of the fuel injection valves is abnormal. In this embodiment as well, as in the embodiment of FIG.
It is detected by a routine executed by U20. If any one of the fuel injection valves is abnormal at step 301, at step 303, the intake valve 5 of the fuel pump 5
A is opened to stop the fuel supply to the common rail, and in step 305, the fuel injection valve in which an abnormality has occurred is determined. Then, in step 307, the value of the increase flag XI is set to 1, and the routine is terminated. Increase flag X
When the value of I is set to 1, in the fuel injection routine separately executed by the ECU 20, the fuel injection amounts from the normal fuel injection valves other than the fuel injection valve having the abnormality determined in step 305 are uniform. The amount is increased at a predetermined rate. If no abnormality has occurred in any of the fuel injection valves in step 301, the routine proceeds to step 309.
Then, the value of the increase flag XI is set to 0, and the routine ends. In this case, a normal amount of fuel injection is performed in a separately executed fuel injection routine.

Next, another embodiment of the present invention will be described. In the embodiment of FIG. 3, the common rail 3 can be shortened in a short time by increasing the fuel injection amount from the normal fuel injection valve.
The internal fuel pressure was decreasing. However, as described above, if the fuel injection amount from the normal fuel injection valve is significantly increased, the in-cylinder pressure and the output torque increase even in the normal cylinder, so that the fuel increase in the embodiment of FIG. The width is naturally limited, and there is a possibility that the time required for the pressure of the common rail 3 to decrease cannot be significantly reduced.

Therefore, in the present embodiment, when an abnormality is detected, the fuel injection amount from a normal fuel injection valve is greatly increased, and the fuel injection timing of each fuel injection valve is retarded to thereby prevent an abnormal increase in the in-cylinder pressure or the like. This prevents a sudden increase in output torque. As is well known, when the fuel injection timing is retarded, the timing at which combustion occurs in the cylinder shifts to the later stage of the explosion stroke, so the exhaust valve opens before the in-cylinder pressure is sufficiently increased. Even if a large amount of fuel is injected, the in-cylinder pressure does not increase. Further, if the injection timing is further retarded, for example, fuel is injected during the exhaust stroke of each cylinder,
Substantially no combustion occurs in each cylinder. Therefore, by delaying the fuel injection timing of each fuel injection valve and greatly increasing the fuel injection amount of the normal fuel injection valve,
The discharge speed of the fuel from the common rail 3 can be further increased as compared with the embodiment of FIG. 3, and the fuel pressure in the common rail 3 can be reduced in a shorter time.

FIG. 4 is a flow chart similar to FIG. 3 showing the abnormal-time control operation of the present embodiment. This control operation is performed as a routine executed by the ECU 20 at regular intervals. When the routine is started in FIG. 4, in step 401, it is determined whether or not any of the fuel injection valves is abnormal. Also in this embodiment, similarly to the embodiment of FIG. 2, the presence or absence of abnormality of each fuel injection valve is detected by a routine separately executed by the ECU 20. If any of the fuel injection valves is abnormal in step 401, the intake valve 5a of the fuel pump 5 is opened in step 403 to stop supplying fuel to the common rail, and an abnormality occurs in step 405. Determine the fuel injector.

In step 407, the value of the increase flag XI is set to 1 as in FIG. 3, and in step 409, the value of the retard flag XR is set to 1, and the routine ends. In the present embodiment, similarly to the embodiment of FIG. 3, when the increase flag XI is set to 1, E is separately set.
According to the fuel injection routine executed by the CU 20, the fuel injection amount from the fuel injection valve in which no abnormality has occurred is uniformly increased at a predetermined rate. In the present embodiment, the increase width of the fuel injection amount is shown in FIG. Is set to be larger than that of the embodiment. Further, when the value of the retard flag XR is set to 1 in step 409, the fuel injection timing of each fuel injection valve is retarded in the fuel injection routine, and for example, the fuel injection is performed during the exhaust stroke of each cylinder. become. As a result, the injected fuel does not contribute to the combustion, and the abnormal increase of the in-cylinder pressure and the increase of the output torque due to the increase of the fuel are prevented.

If no abnormality has occurred in any of the fuel injection valves in step 401, step 41
The values of the flags XI and XR are both set to 0 at 1 and 413, and normal fuel injection is performed in the fuel injection routine.
Although it depends on the type of engine and the fuel pressure in the common rail, according to experiments, for example, when the fuel injection from the normal fuel injection valve is stopped when an abnormality is detected, the fuel pressure in the common rail is sufficiently low. Approximately 10 injection cycles are required for each cylinder before the fuel injection from the fuel injection valve that has dropped and failed is stopped, but the normal fuel injection is also performed from the normal fuel injection valve. Is continued, the pressure in the common rail decreases in approximately five injection cycles. Further, when the fuel injection amount is increased to such an extent that the in-cylinder pressure and output torque of a normal cylinder do not excessively increase when an abnormality is detected, the pressure in the common rail decreases in approximately three to four injection cycles, and the injection timing further increases. It has been confirmed that the common rail pressure drop time can be reduced to about 1 to 2 cycles when the amount of increase is increased by retarding.

[0038]

According to the present invention, the fuel pressure in the common rail is reduced in a short time when an abnormality occurs in the fuel injection, so that the abnormality in the cylinder connected to the fuel injection valve in which the abnormality has occurred is detected. The common effect that the period during which the pressure rise occurs is shortened and the durability of the engine is improved is obtained.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of an embodiment of a fuel injection device of the present invention.

FIG. 2 is a flowchart illustrating an embodiment of an abnormal time control operation of the present invention.

FIG. 3 is a flowchart illustrating an embodiment of an abnormal time control operation of the present invention.

FIG. 4 is a flowchart illustrating an embodiment of an abnormal state control operation of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Fuel injection valve 3 ... Accumulation chamber (common rail) 5 ... Fuel injection pump 10 ... Internal combustion engine 20 ... Control circuit (ECU) 31 ... Fuel pressure sensor

Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02D 45/00 345 F02D 45/00 345K 345L F02M 63/00 F02M 63/00 C

Claims (4)

[Claims] 1. A fuel pump for increasing the pressure of fuel in an internal combustion engine, an accumulator for storing high-pressure fuel supplied from the fuel pump, and a plurality of fuels connected to the accumulator and injecting fuel in the accumulator into the internal combustion engine. An injection valve, abnormality detection means for detecting abnormality of the fuel injection valve, and stopping fuel supply from the fuel pump to the pressure accumulating chamber when abnormality of any one of the fuel injection valves is detected by the abnormality detection means. Means for reducing the fuel pressure in the accumulator by discharging fuel in the accumulator when the abnormality of the fuel injection valve is detected by the abnormality detector. apparatus. 2. The fuel injection according to claim 1, wherein the pressure reducing means reduces the fuel pressure in the accumulator by performing fuel injection from all fuel injection valves including the fuel injection valve in which the abnormality is detected. apparatus. 3. The pressure reducing means further calculates a fuel injection amount from a fuel injection valve other than the fuel injection valve in which the abnormality is detected.
The fuel injection device according to claim 2, further comprising an abnormal time increase unit that increases the amount before the abnormality is detected. 4. An abnormal-time retarding means for delaying fuel injection timing from at least one fuel injection valve other than the fuel injection valve in which the abnormality is detected.
A fuel injection device according to claim 3.