JPH0251065B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of controlling a fuel injection device for an internal combustion engine, particularly a diesel engine, when the fuel injection device malfunctions.

Electronically controlled fuel injection devices have been widely used so far, and include a pressure system consisting of a piston and a plunger, an injection nozzle, a valve mechanism that mainly controls the operation of the pressure system, and a valve mechanism that adjusts the amount of injection. Each cylinder is provided with an injector device consisting of an actuator and operated by control signals from a control device based on information from various detectors. Because of their good controllability, many of these types use electromagnetic valves for the valve mechanism that controls the pressure feeding system and the actuator that adjusts the injection amount. A solenoid valve is provided specifically for the amount. However, solenoid valves have a higher failure rate than other functional parts, and stopping with the metering solenoid valve open can lead to engine overrun, which is extremely dangerous. In the conventional control method, which is configured to stop the operation of the engine, even if one cylinder fails, the engine will stop because the engine will experience abnormal vibrations and other operational failures. This avoids the primary danger, but if the malfunction occurs on a highway, on a mountain road in winter, or in a field far from the horizon, the secondary danger, that is, the inability to drive, causes an accident. This can lead to problems such as inviting disasters or making it difficult to return home. Therefore, as a recent user need, it is required to be able to return to the destination as far as possible even if driving performance deteriorates. Conventional methods, of course, cannot satisfy this requirement.

This invention provides fuel injection control that allows engine operation to continue without damaging the engine even if a part of the injector device for a certain cylinder, such as a metering solenoid valve (actuator), fails while remaining open. The purpose is to provide a method.

In the present invention, when it is detected that, for example, an actuator for metering control in the injector device for each cylinder has failed while it is in a state where fuel can be supplied, the failure can be performed without stopping the operation of the failed injector device. mode operation, and the amount of fuel supplied to the pump hydraulic oil chamber below the plunger via the failed actuator is metered by controlling the operation of a valve mechanism that allows the piston and plunger to rise. There is.

Therefore, even if a part of the injector device of a certain cylinder fails, there is no need to stop engine operation, and even if acceleration/deceleration performance deteriorates, a state close to normal operation can be maintained, and the engine can continue to operate normally. Damage to the engine due to overrun or abnormal vibrations can also be avoided.

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, numeral 1 indicates an injector device provided for each cylinder, 2 indicates a high pressure source, and 3 indicates a low pressure source as a whole. The injector 1 has a switching valve 5, such as a spool valve, which slides from side to side in the drawing while keeping the inside of the bore 4 oil-tight, and a switching valve 5, such as a spool valve, which keeps the inside of the bore 6 and 7 oil-tight and slides up and down in a substantially integrated state. It consists of a small-diameter plunger 8, a large-diameter piston 9, an injection nozzle 10 that receives the fuel pumped from the plunger 8, and three electromagnetic valves 11, 12, and 13. The inside of the bore 4 on one side of the switching valve 5 forms a switching valve operating oil chamber 14, and this chamber 14 communicates with the low-pressure pressure source 3 via a solenoid valve 11, which is a two-way on-off valve, and piping 15. , the fuel reservoir tank 1 is connected via a solenoid valve 12, which is also a separate on-off valve.
Connect to 6. On the opposite side of the hydraulic fluid chamber 14, the spring 17 moves the switching valve 5 to the left in the figure, that is, to the hydraulic fluid chamber 1.
4 is pushed in the direction of making it smaller. A piston hydraulic fluid chamber 18 is formed by the inside of the bore 4 in the intermediate small diameter portion of the switching valve 5 and the bore 7 above the piston 9. This piston hydraulic oil chamber 18
is selectively communicated with the two ports 19 and 20 depending on which of the two left and right positions the switching valve 5 is in. One port 19 connects to the high pressure source 2 via piping 21, and the other port 20 connects to the throttle 22.
is returned to tank 16 via. A pump hydraulic oil chamber 23 formed in the bore 6 on the lower side of the plunger 8 communicates with the nozzle 10 and also communicates with the check valve 2.
4. The above-mentioned metering solenoid valve 1 which is a two-way on-off valve
3 to a low pressure pressure source 3. Control device 3
The input port 0 is electrically connected to various sensors (not shown), and the output port is electrically connected to the three electromagnetic valves 11, 12, 13,
Send control signals to these.

The pressure sources 2 and 3 include pumps 201 and 301, relief valves 202 and 302, and filters 203 and 30.
3. A normal constant oil pressure source consisting of the accumulators 204 and 304 is constructed.

To describe the operation of the system according to the present invention described above, in the position shown in the figure, the solenoid valve 11 is closed and the solenoid valve 12 is open, so the low pressure source 3 is separated from the switching valve operating oil chamber 14, and this Chamber 14 communicates with reservoir tank 16 . Therefore, due to the spring 17, the switching valve 5 assumes the left-hand position, and the port 20 is brought into communication with the piston hydraulic oil chamber 18, so that the fuel in this chamber 18 can be released into the reservoir tank 16. In this state, when a signal giving the solenoid valve 13 an opening time of a length corresponding to the injection amount is input from the control device 30, the valve is opened for this period as shown in the figure, and the low pressure source 3
The fuel is introduced into the pump hydraulic oil chamber 23 via the check valve 24 and filled with a predetermined amount, and then the metering solenoid valve 13 is closed. At this time, the piston 9,
Plunger 8 rises.

When the solenoid valve 11 is switched to open and the solenoid valve 12 is switched to close, the hydraulic pressure from the low pressure source 3 acts on the switching valve operating oil chamber 14 via the pipe 15, and at the same time, this chamber 1
4 is separated from the reservoir tank 16. As a result, the switching valve 5 moves to the right in the figure against the spring 17,
Port 20 is closed and port 19 is opened. Thus, the hydraulic pressure from the high pressure source 2 is guided to the piston hydraulic oil chamber 18 via the pipe 21, and the piston 9 and plunger 8 are moved downward by this hydraulic pressure. At this time, the pressure in the pump working oil chamber 23 is theoretically increased to twice the piston-to-plunger cross-sectional area ratio of the hydraulic pressure of the pressure source 2.
Occurs in 3. This ultra-high pressure fuel is prevented from flowing back by the check valve 24, is supplied to the nozzle 10, and is injected into a combustion chamber of an internal combustion engine (not shown).

The above is the operation during normal operation, and this will be further explained with reference to the timing diagram of FIG. 2. Second
When the first solenoid valve 12 is closed and the first solenoid valve 11 is opened at timing A, the switching valve 5 is moved to the right by the hydraulic pressure, and the piston/plunger is subsequently pushed down, so that fuel is injected. do. Next, at timing B, the first solenoid valve 11 is closed,
When the second electromagnetic valve 12 is opened, the switching valve 5 is pushed back to the left. The second solenoid valve 12 is then closed. In this state, the third solenoid valve is opened from timing C and kept open until timing D.
During this time, the plunger and piston are pushed up and the injected fuel is introduced. What is shown in FIG. 1 is the state during this period. When the third solenoid valve is closed at timing D, timing A of the next cycle returns in that state. At this time, it can be seen that the injection amount is controlled at the time CD.
In the case of partial load, the third
Shorten the opening time of the solenoid valve. For example, in fig.
If CD' is set, the plunger and piston will stop rising at point D', and the injected fuel introduced up to that point will become the injection amount for the next injection. If the opening time of the third electromagnetic valve is further shortened, the injection amount will decrease, and if it is made longer, the injection amount will increase. That is, the control device 30 controls the third solenoid valve 13 according to the magnitude of the required load (starting, idling, running, etc.) based on inputted various sensor information such as cooling water temperature and intake air temperature. A signal is supplied to the valve opening time corresponding to the fuel injection amount. Normally, as the load increases, the opening time of the third solenoid valve increases. Further, as described above, in the case of partial load, the control valve opening time becomes CD' as shown by the broken line in FIG.

Next, a method for controlling failure modes will be explained using a similar timing diagram in FIG. What should be noted here is that the third solenoid valve 13 remains open and does not operate. Therefore, the third solenoid valve is not energized and is not shown in the figure.

The first solenoid valve 11 is opened at timing A in the figure, and the process leading to injection is the same as in normal operation. Therefore, in normal operation, the second solenoid valve 12 opens immediately after timing A, as shown in B in FIG.
Adjustment by the third electromagnetic valve 13 is enabled and the valve is on standby, but under conditions of failure, the valve opening time is set to be later than this, and the injection amount is controlled using this valve opening time. That is, the timing B is determined by reversing the timing A of the next cycle (the opening time of the first solenoid valve 11) by the same length as the control valve opening time CD of the normal operation in FIG. Open the valve 12. Here, the timing A of the next cycle is calculated from the engine rotation speed, and an estimated timing is used. Therefore, specifically, after the time obtained by subtracting the necessary metering time (equivalent to CD) from the calculated injection interval has elapsed from timing A, the second
This will open the solenoid valve 12. Since the third solenoid valve 13 has already been opened due to a failure, by opening the second solenoid valve 12 in this state and releasing the hydraulic pressure in the switching valve operating oil chamber 14 to the reservoir tank 16. , the switching valve 5 moves to the left by the force of the spring 17, the port 19 closes, and the port 20 opens, so that the piston hydraulic oil chamber 1
8 is released to the reservoir tank 16, and therefore the piston 9 and plunger 8 are pushed up,
Injected fuel from the pressure source 3 is introduced into the pump hydraulic oil chamber 23 through the third electromagnetic valve 13 which is in an open state. After the switching valve 5 has been moved to the left, the second
The solenoid valve 12 is closed, but fuel continues to be introduced. Next, at timing A of the next cycle, that is, injection timing, the eleventh solenoid valve 11 is opened again, the switching valve 5 is moved to the right, and the port 20 is closed. 19 is opened, and injection starts again. Therefore, the injection amount is controlled at timing A of the next cycle.
This is done according to the time of BA. Specifically, the timing A of the next cycle is estimated and calculated,
Then, the time BA goes back is measured by the time from timing A, and it is calculated by the time AB. Similarly to Fig. 2, in the case of a partial load, the result will be as shown by the broken line in the figure, and if timing B is delayed, for example, as shown in B', the control time BA
becomes shorter than B′A, and during that time the stroke that the plunger and piston can ascend becomes smaller, reducing the injection amount. Furthermore, the injection amount decreases as it approaches timing A of the next cycle, and increases as it moves away from it. In this mode, as mentioned before, metering accuracy during acceleration and deceleration is poor. This is because A of the control time BA is the injection timing of the next cycle, and the timing of B is determined by anticipating this. During acceleration and deceleration, the timing of A in the next cycle is expected at timing B. This is because it becomes different from what it was.

However, it is sufficient for the purpose of somehow continuing to operate the engine.

Next, the overall control flow will be explained according to the flowchart shown in FIG. After setting the initial conditions, input various sensor information. Examples include TDC mark, engine speed, accelerator position, cooling water temperature, lubricating oil temperature, intake air temperature, intake air pressure, exhaust temperature, pressure source pressure, etc. As will be described later, an abnormality in the metering solenoid valve 13 is detected based on the sensor information, and if there is no failure, the control device 30 calculates metering and timing in the normal mode, and performs control as shown in FIG. do. Then, sensor information is input again, and calculations are performed moment by moment through this loop. When a failure is discovered, it enters failure mode, calculates metering and timing, and performs control as shown in Figure 3. In a system where the faulty cylinder is known, this may be only the faulty cylinder, otherwise it may be all cylinders. Here, the failure detection method uses, for example, a rotational speed sensor that can detect the instantaneous rotational speed, such as one that outputs a pulse every fixed rotation. The control device 30 monitors this and considers it as abnormal when the rotational fluctuation for each explosion exceeds a predetermined reference fluctuation range. Alternatively, there is a method of providing a piston position sensor to feed back the intake amount.

In the present invention, if the metering actuator fails while still being able to supply fuel, failure mode operation is possible with the same control as above even if a 2-position 3-port solenoid valve is applied to the solenoid valves 11 and 12. become. Regarding the control of the 2-position 3-port solenoid valve in this case, for example, the switching valve hydraulic oil chamber 1
The four sides are used as a common flow path, and the fuel switching valve operating oil chamber 1
The inflow and outflow to 4 are timing A and timing B.
It is carried out to correspond to Further, the present invention can be applied to any method as long as metering and pressure feeding drive are controlled by separate actuators. For example, a solenoid direct-acting type in which the switching valve 5 itself is not actuated by a hydraulic solenoid valve but is moved directly by electromagnetic force can of course be used. Furthermore, it goes without saying that the structure and number of pressure sources and the type of hydraulic oil do not matter, as well as the type of nozzle, and the present invention can also be applied to those with mechanical improvements such as providing a spill circuit in the plunger. is obvious.
Further, although a digital control circuit is used in the embodiment, it is of course possible to implement this with an analog circuit. Further, the metering solenoid valve 13 may be of a different type, and its arrangement may be between the port 20 and the fuel tank instead of between the low pressure source 3 and the check valve 24 as shown in FIG. It may be between the reservoir tank 16 and the reservoir tank 16. However, in this case, the amount of fuel introduced is adjusted not by the metered fuel itself, but by adjusting the amount of hydraulic oil flowing out of the piston hydraulic oil chamber 18. In that case, the metering solenoid valve 13 may be placed either upstream or downstream of the throttle 22. In addition, in this case, the throttle 22 for setting the rising speed of the plunger 8 and piston 9 during metering is not arranged as in the embodiment shown in FIG. For example, it may be moved to the upstream side of the check valve 24.

What should be noted here is that if a part of the metering circuit other than the solenoid valve malfunctions, for example, the throttle falls off,
Depending on the configuration of the abnormality detection means, there is a possibility that a malfunction of the solenoid valve may be mistakenly detected because the injection amount changes. In such a system, if only that cylinder operates in the failure mode, the third solenoid valve will not be energized, and the metering solenoid valve will remain closed, so the injector will stop injecting into that cylinder. Ru. In other words, it becomes a failure mode operation in which the operation of the abnormal cylinder is stopped. Furthermore, when operating in a high-grade failure mode that avoids stopping the operation, if you later detect that the operation has stopped using the same method, it becomes clear that the failure was not a failure of the solenoid valve (electromagnetic valve). (If the valve is malfunctioning, the accuracy will be lower as mentioned above, but it will operate.) Therefore, for example, by controlling the control timing shown in Figure 5, the opening time of the metering solenoid valve can be changed from the normal CD to CD''. It is best to move to the second failure mode, which is to change and shorten the time.Here, D'' is the case where the plunger and piston rise speed increases due to the dropout of the throttle, and the fuel introduction time becomes shorter. , indicates the proportionally corrected timing. The dash-dotted line in the figure indicates normal operation.

As mentioned above, in the present invention, a pumping drive system,
Each cylinder is equipped with an injector device that has a valve mechanism that controls its operation and a separate actuator for metering, and inputs various sensor information.
In a fuel injection system that outputs signals to control the valve mechanism and actuator from the control device, when a part of the injector device fails in a state where fuel can be supplied, that is, on the injection amount increasing side, the actuator that performs metering or the pressure feeding drive system By operating the valve mechanism that controls the operation in a failure mode, metering is possible, without stopping engine operation, and it is possible to avoid dangers such as overruns caused by failures. Moreover, when using digital circuits, this method basically requires additional configuration,
It also has the advantage that it can be implemented by simply changing the control program without any changes.

[Brief explanation of the drawing]

Figure 1 is a schematic configuration diagram of an embodiment of the present invention, Figure 2 is a control/operation timing diagram in normal mode, and Figure 3 is a diagram of control/operation timing in normal mode.
The figure is a control/operation timing diagram in failure mode, and Figure 4 is a flowchart showing the overall control flow.
FIG. 5 is a control operation timing diagram in a failure mode in another embodiment of the present invention. 1... Injector device, 2, 3... Pressure source,
5...Switching valve, 8...Plunger, 9...Piston, 10...Injection nozzle, 11, 12...First,
Second solenoid valve, 13... metering actuator (third solenoid valve), 30... control device.

Claims (1)

[Scope of Claims] 1. A pressure feeding system that includes a piston and a plunger connected to the piston, and that pumps fuel in a pump operating oil chamber below the plunger under pressure by the piston; An injection nozzle that injects the pumped fuel; and Above the piston. It consists of a valve mechanism that controls the vertical movement of the piston and plunger by changing the oil pressure in the piston hydraulic chamber, and an actuator that adjusts the amount of fuel supplied to the pump hydraulic chamber below the plunger, that is, the amount of fuel injection. In a fuel injection control method for an internal combustion engine in which each cylinder is provided with an injector device that is operated by a control signal from a control device based on information from a detector that detects the operating state of the engine, a portion of the injector device supplies fuel. If a failure occurs while the injector device is in a capable state, the fuel injection amount is controlled by controlling the operation of the above-mentioned metering actuator or the above-mentioned valve mechanism so that at least the operation of the failed injector device can be operated in a failure mode. In the injection control method, the operation of the valve mechanism in the failure mode operation is controlled by reducing the oil pressure in the piston hydraulic oil chamber above the piston to adjust the timing when the plunger can rise to the normal fuel injection timing. 1. A fuel injection control method for an internal combustion engine, characterized in that the amount of fuel supplied to a pump hydraulic oil chamber below a plunger through a faulty metering actuator is controlled so as to start a predetermined amount of time earlier than a predetermined time. 2. A fuel injection control method for an internal combustion engine according to claim 1, wherein the actuator is a solenoid valve.