JPH0211731B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection control device for a multi-cylinder internal combustion engine, particularly a diesel engine, and more particularly to an electronically controlled fuel injection control device having a fuel injection device for each cylinder.

Conventional fuel injection control devices for multi-cylinder internal combustion engines include a fuel injection device using an electric actuator for each cylinder, and fuel injection is individually controlled by control electric signals from the control device (for example,
49-12229). However, if, for example, a failure occurs in the metering system of the fuel injection device and the injection amount becomes uncontrollable, and the injection amount happens to be on the increasing side, the engine will overrun, resulting in an extremely dangerous situation. It does not have any preventive function against this. Furthermore, if a failure occurs that suddenly stops injection to a certain cylinder, the engine cannot maintain balance and abnormal vibrations occur, but this cannot be prevented either.

In particular, if the above-mentioned metering system malfunctions and the injection amount continues to increase and becomes uncontrollable, the engine will overrun, potentially endangering human life. In particular, even the electronic control unit with a computer had a safety function that stopped injection and engine operation in the event of this failure. However, this safety function had the following drawbacks and did not meet the needs of recent users. It is something. In other words, if this failure occurs while driving on a highway, a mountain road in winter, a farm road where people rarely live, or if the engine is being used as a power source for hydraulic equipment for working hydraulic equipment, stop operation. This is to create a secondary danger. Therefore, even if a failure occurs, it is important to continue operating the engine without stopping it and reach a safe location.

An object of the present invention is to provide a fuel injection control device for a multi-cylinder internal combustion engine that can continue operation in a failure operation mode without stopping engine operation even if an abnormality occurs in the fuel in the fuel injection device of any cylinder. It is to provide.

In the present invention, for each fuel injection device provided for each cylinder, the control device determines whether there is an abnormality in fuel injection based on detection data from a sensor that detects the operating state of the engine, and When an abnormality in the fuel injection device is determined, the control device supplies a control electric signal to the fuel injection device of each cylinder in a control mode different from that during normal operation to continue operating the engine.

In this control mode different from normal operation, for example, a control signal to stop fuel injection is sent to a fuel injection device that has experienced an abnormality, and
Stop fuel injection for the fuel injector of at least one other cylinder that has a specific arrangement order relationship between the arrangement order of the cylinder related to the abnormal fuel injection device and the balance of output generation, or A control signal is provided to reduce the number of injections.

Therefore, in the past, if the fuel injection device of any cylinder became abnormal, the operation of the engine had to be stopped, but in the present invention, a control signal for a control mode different from that during normal operation is used. By supplying fuel to each cylinder's fuel injection system, the engine's operating performance will be lower than normal operation, but operation can continue without damage to the engine due to abnormal vibrations caused by unbalanced output between the engine's cylinders. . Therefore, it is possible to prevent various dangers due to engine operation stoppage on expressways, mountain roads in winter, etc., and improve safety functions.

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows an electronically controlled hydraulically driven diesel fuel injection system (for one cylinder) as an example of a fuel injection system for each cylinder according to the present invention.

In FIG. 1, 1 is an injector, 2 is a high pressure source, 3 is a low pressure source, and 4 is a control device. The injector 1 consists of a spool valve 5, a plunger 8, a piston 9, a nozzle 10, first, second, and third solenoid valves 11, 12, 13, a throttle 22, and a check valve 24, and the pressure sources 2 and 3 are a pump and a relief valve. It constitutes a normal constant oil pressure source consisting of a valve, filter, and pressure accumulator. Further, the control device 4 is connected to various sensors (not shown), and the three electromagnetic valves 11, 12,
13.

FIG. 2 shows 6 of the fuel injection control device according to the present invention.
This is an example of a cylinder engine. The engine 100 is equipped with six fuel injection devices 1 including the spool valve 5, plunger 8, piston 9, nozzle 10, solenoid valves 11, 12, 13, etc. shown in FIG.
0 is equipped with sensors for crank angle, water temperature, etc., and is connected to the control device 4. On the other hand, pressure pipes from the hydraulic power sources 2 and 3 shown in FIG. 1 are connected to each fuel injection device 1, and installed pressure sensors are connected to a control device 4. The control device 4 is composed of a microcomputer and a solenoid valve drive circuit, and detects the operating state of the engine using various sensors and performs control according to a program. The control device 4 is capable of independently controlling the fuel injection device 1 of each cylinder. Furthermore, with the recent development of microcomputers, various types of arithmetic processing have become faster, and by utilizing this, it is possible to independently control not only each cylinder but also the injection itself each time in each cylinder.

In terms of operation, control signals are sent from the control device 4 to the solenoid valves 11, 12, 1 according to information from various sensors.
3 is output. The spool valve 5 is actuated by the electromagnetic valves 11 and 12, thereby controlling the hydraulic pressure applied to the piston 9 that drives the plunger 8. The plunger 8 piston 9 increases the hydraulic pressure supplied from the pressure source 3 and injects fuel from the nozzle 10. The injection amount is controlled by the solenoid valve 13 according to the control electric signal calculated and output by the control device 4.
opens and closes, and the injected fuel is introduced into the lower part of the plunger 8 in the state shown in FIG. 1 (plunger 8 and piston 9 are raised), and this is done by controlling the time during which this solenoid valve 13 is open. At this time, a throttle 22 is provided to reduce the rate of change in the injection amount with respect to time. The injection device shown here as an example is already well known and its operation is well known, so further detailed explanation will be omitted.

Next, to explain the safety function when an injection abnormality occurs, which is the main focus of the present invention, during normal operation as described above, for example, if the solenoid valve 13 remains open and cannot be reset, or if the throttle 22 falls off. Furthermore, if a short circuit occurs in the signal line of the solenoid valve 13 or a pressure abnormality occurs in a faulty pressure source at the output stage of the control device, the injection amount becomes extremely large and control becomes difficult. As mentioned above, this leads to an overrun of the engine and causes an extremely dangerous phenomenon. The risk is especially high when there is a failure in the control device that affects all six cylinders. Such a state can be properly recognized by the computer based on information from the various sensors described above, such as crank angle, exhaust temperature, exhaust emission, etc. Further, the presence or absence of an abnormality in the injection device for each cylinder can also be determined based on fluctuations in engine speed corresponding to the combustion timing of each cylinder. Therefore, the computer of the control device 4 switches the operating conditions to a failure mode and safely continues the minimum operation while notifying the driver of the failure.

Now, to explain the failure mode operation in more detail, the configuration of the present invention has a major feature in that each cylinder and each injection can be controlled independently and freely as described above. Therefore, when a failure occurs and the number of failed cylinders is small, such as only one, in other words, when there is only one injector with an injection abnormality, only the failed cylinder is stopped and other necessary operations are performed according to the needs of the mechanical and thermal balance of the engine. Injection is also stopped in the cylinders, or injection is stopped intermittently. Furthermore, in order to secure the required torque for the engine as a whole, it is possible to increase or decrease the injection amount in other operating cylinders. In the event of a failure involving all cylinders, the number of cylinders to be activated is determined based on the engine output, and other cylinders are shut down to reduce the overall injection amount. At this time, the position of the operating cylinder may be changed over time in consideration of mechanical balance. As mentioned above, this can be controlled for each injection. In this case as well as in the case of a small number of failures mentioned above, the selection of cylinders to achieve balance is obvious, although it depends on the number of cylinders, the arrangement of the cylinders, the type of engine, and the design parameters of the engine, although it differs from engine to engine. It is possible to set it in advance from

FIG. 3 is a flowchart showing the flow of this control. Particular attention should be paid here to the fact that these controls are repeatedly performed from time to time, and as a result, the conditions can be changed for each injection, as described above.

Next, to explain in more detail with reference to timing diagrams, FIG. 4 shows a known injection device 1.
FIG. 3 is a timing diagram showing the operation of the injector. As can be seen from the figure, three solenoid valve signals are output for one injection. Here, the timing of the engine rotation for one injection is shown in FIG. 5. Here, what is indicated by A in the figure is one injection per cylinder. In the example 1-5
The case of a 6-cylinder engine that explodes in the order -3-6-2-4 is shown.

As an example, we will discuss failure mode operation when the 6th cylinder malfunctions due to an abnormally large injection amount. Figure 6 shows an example of failure mode operation. First, the 6th cylinder, which is in trouble, is de-energized and activated. stop. Furthermore, in order to balance the engine, the 4th and 5th
The cylinders also stop operating and continue to operate.
Since the output is halved here, the injection amount in the first, second, and third cylinders may be increased if necessary and conditions permit.

An example of operation in another mode is shown in FIG. In this example, the faulty 6th cylinder stops injection, and the 4th and 5th cylinders operate at a reduced speed to reduce the number of injections. That is,
The fourth cylinder explodes (fuel injection) every other time, and the fifth cylinder explodes every third time. This example is an intermediate operation between normal operation and the example shown in FIG.

As another example of a failure mode, in order to more effectively deal with a relatively minor case such as a loosening of the throttle 22, the metering time of the failed cylinder (solenoid valve 13 Power-on time (Fig. 4 CD)
It is also possible to add something that shortens the .

Further, in the failure mode of the embodiment, the number of cylinders is varied, but it is also possible to vary the number of cylinders while operating all cylinders, or it is of course possible to mix both. The optimal pattern for operating conditions in these failure modes should be selected depending on the target engine, how the engine is used, and the failure situation.

The failure mode in the metering system described in the embodiment is the injection control system (in the illustrated embodiment, the spool valve 5,
It can be seen that even when the plunger 8, piston 9, solenoid valves 11, 12, pressure source 2, relevant output part of the control device 4, etc.) become abnormal and normal injection cannot be performed, by adding a discrimination algorithm, it can be applied almost as is. . In other words, it is possible to prevent the engine from becoming unbalanced by stopping the failed cylinder, and to continue safe operation. However, in this case, care must be taken because it cannot be applied in the case of a failure involving all cylinders, that is, when all cylinders are unable to inject.

Summarizing the above, it can be seen that for all injection device abnormalities, operation can be continued by switching to the appropriate failure mode operation.

For example, an injection device is the simplest device that uses fuel as the hydraulic fluid in a hydraulic system. Needless to say, the present invention can be applied even if the piping etc. are changed, and the structure of the injection device 1 itself may also be different from the illustrated example.

In addition, although a microcomputer is used as the control device in the embodiment, if conditions permit, such as in low-speed engines, it is possible to configure this with an analog circuit, or conversely, it can be configured with a multiprocessor system. is also possible.

Furthermore, for failure modes, it is more effective to switch or combine appropriate modes without being limited to one pattern.

It is also effective to equip an intake shutter, decompressor, etc. during failure mode and control them together.

In the present invention, a control device inputs various sensor information and outputs an actuator signal;
Each cylinder has an injector that can operate independently, and when an injector failure causes an undesirable engine operation, the control device detects this and switches the operation to a failure mode.
For example, in the case of a malfunction in the metering system, the engine can continue to operate safely without stopping the engine with parts that cannot be metered in, and without causing damage to the engine due to abnormal vibrations caused by unbalanced output between each cylinder of the engine. It has the effect of being possible.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a schematic configuration example for one cylinder of a fuel injection device used in an embodiment of the present invention, FIG. 2 is a diagram showing an embodiment of a fuel injection control device for a six-cylinder engine, and FIG. The figure is a flowchart showing the flow of control,
Figure 4 is a timing diagram of the operation of each electromagnetic valve, spool, etc. of the fuel injection device for one injection, Figure 5 is a normal timing diagram of control signals for a six-cylinder engine, and Figures 6 and 7 are The figure is a timing diagram of failure mode operation for control signals of a six-cylinder engine. In the figure, 1... fuel injection device, 2, 3...
Pressure source, 4...Control device, 5...Spool valve, 8
... Plunger, 9 ... Piston, 10 ... Nozzle, 11, 12, 13 ... Solenoid valve, 100 ... Engine.

Claims (1)

[Scope of Claims] 1. A fuel injection device provided for each cylinder that can control fuel injection by an electric signal, a sensor that detects the operating state of the engine, and based on the operating state of the engine detected by the sensor,
It is determined whether or not there is an abnormality in the fuel injection in the fuel injection device of each cylinder, and when it is determined that there is an abnormality in the fuel injection device of any cylinder, the control electric power that is different from that during normal operation, which is necessary to continue operating the engine, is determined. It consists of a control device that supplies signals to the fuel injection device of a predetermined cylinder, and the control device is configured to detect the fuel injection device in which the abnormality has occurred,
and a control electric signal for forcibly restricting fuel injection for a normal fuel injection device of at least one cylinder that has a specific arrangement order relationship in terms of balance between the arrangement order of cylinders related to the fuel injection device and output generation. A fuel injection control device for a multi-cylinder internal combustion engine, characterized by supplying the following: