JPS63246446A - Control device for engine - Google Patents

Abstract

PURPOSE:To suppress the air fuel ratio of the intake air from becoming over- lean by reducing the maximum filling quantity of the intake air to an engine when the fuel discharge quantity from fuel pumps is decreased. CONSTITUTION:Under a high load of an engine 1 judged by a control unit 32, when the fuel discharge quantity is decreased than the preset value due to the failure or the like of a fuel pump 26 or 27, it is detected by a pressure sensor 35. An electromagnetic clutch mechanism 14 is turned off by the operation of the control unit 32 fed with the output signal of this detecting means, a supercharger 15 is stopped operating, and the maximum filling quantity of the intake air filled in the operation chamber 4 of the engine 1 is corrected to be decreased. That is, as the fuel discharge quantity of the fuel pump 26 or 27 is decreased, the maximum filling quantity of the intake air is reduced, thus even if the air fuel ratio of the intake air tends to become over-lean under a high load of the engine 1, it is suppressed by the decreasing correction of the filling quantity of the intake air.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an engine control device, and particularly to measures against abnormalities in a fuel pump that supplies fuel in a fuel tank to an engine.

(Prior Art) Conventionally, as a technology for controlling the operation of this type of fuel pump, for example, as disclosed in Japanese Patent Laid-Open No. 58-48767M, the operating state of the engine is detected and the fuel pump is controlled according to the operating state. It is known that by variable control of the voltage applied to the fuel pump, the voltage applied to the fuel pump is lowered and the operating noise is reduced during low load and low rotation times, including when the engine is idling. .

(Problems to be Solved by the Invention) By the way, by using the concept of the above-mentioned conventional example, for example, in a fuel injection type engine, the fuel discharge t of the fuel pump is variably controlled according to the load condition of the engine, and the engine speed is increased. It is conceivable to increase the accuracy of fuel injection control for injecting fuel from a fuel injection valve into a combustion chamber of an engine by increasing the amount of fuel discharged from a pump in a load range.

However, in that case, the following problem arises.

That is, in general, in a fuel injection type engine, the fuel in the fuel tank is pumped to the fuel injection valve by a fuel pump, and the fuel is injected and supplied to the combustion chamber by opening the fuel injection valve. For some reason, the voltage applied to the fuel pump may drop significantly, or the fuel pump itself may malfunction, causing the amount of fuel discharged from the fuel pump to be lower than normal. When the amount of fuel injected from the fuel injection valve decreases, the actual amount of fuel 9A injected from the fuel injection valve decreases from the target value even though a pulse signal with a normal pulse width is applied to the fuel injection valve. As mentioned above, when the fuel pump's fuel discharge amount is made to correspond to the engine load, the difference between the target value and the actual value of the fuel injection amount becomes so large that it cannot be ignored, especially in the high engine load range. , the intake air-fuel ratio becomes over-lean. As a result, the so-called enriching effect of the exhaust gas purification device disposed in the exhaust system of the engine is impaired, causing a problem in that the temperature thereof rises excessively.

The present invention has been made in view of the above, and its purpose is to appropriately correct the intake air flow to the engine when the fuel discharge layer decreases due to a failure of the fuel pump, etc. as described above. The object of the present invention is to suppress the air-fuel ratio of intake air from becoming overly lean even when the fuel discharge layer from the fuel pump decreases, thereby preventing an excessive temperature rise in the exhaust gas purification device.

(Means for solving the problem) In order to achieve this object, the solution of the present invention is such that when the fuel discharge layer from the fuel pump decreases, the maximum charge of intake air to the engine is reduced accordingly. I have to.

That is, the present invention, as shown in FIG. In an engine equipped with a fuel pump 53 that supplies a fuel metering device 52, a discharge amount reduction detection means 36 is provided to detect when the fuel discharge amount has decreased below a set value due to a failure of the fuel pump 53 or the like.

Further, in response to the output of this detection means 36, the fuel pump 53
The structure includes an intake air filling amount correcting means 37 that corrects the maximum filling amount of intake air to be filled into the combustion chamber 4 of the engine to decrease when the fuel discharge amount of the engine decreases.

(Function) With this configuration, in the present invention, when the fuel discharge amount decreases below the set value due to a failure of the fuel pump 53 or the like when the engine is under high load, this is detected by the discharge amount decrease detection means 36, Upon receiving the output signal of the detection means 36, the intake air filling amount correcting means 37 operates, whereby the maximum filling amount d of the intake air filled into the combustion chamber 4 of the engine is corrected to decrease.

In other words, the maximum filling amount of intake air decreases as the fuel discharge layer of the fuel pump 53 decreases, so even if the air-fuel ratio of intake air tends to become overlean when the engine is under high load, this will result in a reduction in the amount of intake air filling. This can be suppressed by correction, and therefore, it is possible to effectively prevent the temperature of the exhaust purification device disposed in the engine exhaust system from rising excessively.

(First example) Embodiments of the present invention will be described below based on the drawings.

FIG. 2 shows the overall configuration of the first embodiment of the present invention, in which reference numeral 1 is a partially supercharged rotary piston engine installed in a 1Ill car, and this engine 1 has a rotor housing 2a and a A working chamber 4 as a combustion chamber defined by a rotor 3 is provided within a housing 2 consisting of a pair of one-noid housings 2b, 2b (only one of which is shown). 5 is an intake passage that supplies intake air into the working chamber 4 of the engine 1; 19 is an exhaust passage that discharges exhaust gas from the working chamber 4; the intake passage 5 is composed of a main passage 6 and a supercharging passage 9; , the upstream ends of both passages 6 and 9 are connected to an air cleaner 10.
It is connected to the. An air flow meter 11 for detecting the amount of air flowing through the main passage 6 is disposed on the upstream side of the main passage 6. Further, the downstream portion of the main passage 6 is divided into a primary passage 7 and a secondary passage 8, and primary and secondary throttle valves 12 and 13 are disposed in these passages 7 and 8, respectively. The intake boat 7a constituting the downstream end of the primary passage 7 is attached to one side housing 2b of the housing 2.
Intake boats (not shown) as downstream ends of the secondary passages 8 are opened in the other side housing.

In addition, an intake boat 9 constituting the downstream end of the supercharging passage 9
a is opened in the one side housing 2b. In addition, in this supercharging passage 9, in order from the upstream side, there are a Roots type supercharging pump 15 which is drivingly connected to the engine 1 via an electromagnetic clutch groove 14 to supercharge the intake air, and a roots type supercharging pump 15 which performs heat exchange between the intake air and the air. an air-cooled intercooler 16 that is cooled by;
A hot wire type air flow sensor 17 that detects the amount of air flowing through the supercharging passage 9 and a rotary valve 18 that rotates in synchronization with the engine 1 to open and close the supercharging passage 9 are provided.

On the other hand, in the exhaust passage 19, a catalytic exhaust purification device 20 for purifying exhaust gas and a silencer 54 are disposed in order from the upstream side thereof. Further, an exhaust boat 19a constituting the upstream end of the exhaust passage 19 is opened to the rotor housing 2a.

Furthermore, a high flow rate injector 22 (fuel injection valve) is disposed in the primary passage 7 of the main passage 6 constituting the intake passage 5 to inject fuel into the passage 7. Further, a wide range injector 21 is attached to the rotor housing 2a of the housing 2 in the engine 1 in order to directly inject and supply fuel into the working chamber 4. Therefore, in this embodiment, the two injectors 21 and 22 constitute a fuel metering device 52 that adjusts the fuel supply trough that is supplied into the working chamber 4 of the engine 1.

The two injectors 2'1.22 are communicated with the fuel tank 25 via first and second fuel supply passages 23.24, respectively, and the two fuel supply passages 23.24 are connected to the fuel tank 25, respectively. Injector 21.2
First and second fuel pumps 26 and 27 are provided to supply fuel to the fuel pump 2 (fuel adjustment device 52). Further, both the fuel supply passages 23.24 are connected to the first and second communication passages 28, 29 in the upstream portion of the fuel pump 26.27.
A first fuel switching valve 30 is provided at the branch connection portion between the first communication passage 28 and the second fuel supply passage 24 , and a first fuel switching valve 30 is provided at the branch connection portion between the first communication passage 28 and the second fuel supply passage 24 .
A second fuel switching valve 31 is disposed at the branch connection portion between each injector 21.22 and the fuel pump 26 by switching these fuel switching valves 30.31 to the same ON-OFF state. For example, when both fuel switching valves 30 and 31 are turned ON, the first fuel pump 26 is connected to the wide range injector 21, and the second fuel pump 27 is connected to the high flow rate injector 22. On the other hand, on the other hand, both fuel switching valves 3
0.31 are both turned off, the first fuel pump 26 is communicated with the high flow rate injector 22, and the second fuel pump 27 is communicated with the wide range injector 21, respectively.

An electromagnetic clutch mechanism 14 for controlling the operation of the supercharging ta 15, both injectors 21 and 22, and a fuel pump 26.
27 and fuel switching valves 30 and 31 are operated and controlled by a control unit 32 containing a CPU. This control unit 32 includes the air flow meter 1
1 and air 70-respective output signals of sensor 17 are input. Further, 33 is an engine rotation sensor that detects the rotation speed of the engine 1, 34 is a mileage sensor that detects the mileage of the automobile, and 35 is a pressure sensor that detects the fuel pressure in the second fuel supply passage 24. The output signals of these sensors 33 to 35 are sent to the control unit 3.
2 is entered.

Here, in the control unit 32, the electromagnetic clutch mechanism 14 for controlling the operation of the supercharger 15 is set to 0N.
-OFF switching, 0N-O of both injectors 21.22
A signal for controlling the FF operation, the operation of the fuel pump 26, 27, and the ON/OFF operation of the fuel switching valves 30 and 31 @
The processing procedure will be schematically explained based on FIGS. 3 and 4.

FIG. 3 shows the main routine. In step S1 after the start, the engine rotation speed detected by the engine rotation sensor 33, the intake air 2 detected by the air flow meter 11, and the pressure sensor 35 are detected. After inputting the fuel pressure, steps 82 to 31
Move to 3.

This step 82 to S+3 involves two fuel pumps 26°2
7, and its procedure is performed according to the subroutine shown in FIG. That is,
First, in step $2, the mileage of the automobile detected by the mileage sensor ν34 is read, and in the next step 33, Sa, both the first and second fuel switching valves 30, 31 are switched to the ON state. By turning on the fuel switching valves 30 and 31, for example, the first fuel pump 26 and the second fuel pump 27 are communicated with the wide range injector 21 and the high flow rate injector 22, respectively. Thereafter, the process proceeds to step S5, where it is determined whether or not the mileage is greater than or equal to the first set value. If this determination is No, the process proceeds to the next step 314 in the main routine. Moreover, if the determination becomes YES, the process proceeds to step 36.37, and the first and second fuel switching valves 30.3 are respectively opened.
1 to the OFF state. This fuel switching valve 30
The OFF switching at .degree. 31 causes the first fuel pump 26 to communicate with the high-flow injector 22 and the second fuel pump 27 with the wide-range injector 21, respectively. Further, in step S8, it is determined whether the traveling distance is equal to or greater than a second set value that is larger than the first set value, and when this determination is No, step 31 in the main routine is performed.
On the other hand, if the determination is YES, proceed to step 39.
Proceeding to step 310, the first
and switches the second fuel switching valves 30, 31 to the ON state. Thereafter, in steps 3o to Sea, the same processes as steps 85 to S7 described above are repeated. The switching of the fuel switching valves 30, 31 as described above is achieved by periodically switching the functions of the first and second fuel pumps 26, 27 according to the mileage of the automobile, so that their operating times (operating rates) are made equal. This is done to increase the durability of these pumps 26 and 27.

After such a subroutine, in step S14, one fuel pump 26 (of the first and second fuel pumps 26, 27) that is in communication with the wide range injector 21 is activated.
27) Drive (annihilation pump), then step S'
Proceed to step s to drive the wide area injector 21, and then,
In step S+s, the actual engine speed and intake air amount detected in step S1 are compared against the load characteristics of the engine 1 that have been set in advance according to the engine speed and intake air amount, and the engine It is determined whether the load is in a high load range equal to or higher than the first setting line. Here, if it is determined to be NO due to the low load range of engine 1,
The process directly proceeds to step S+s, but if the determination is YES due to the high load range of the engine 1, the process proceeds to step 317 to drive the other fuel pump 27 (26> (high flow rate pump)) communicating with the high flow rate injector 22. After that, the process proceeds to step S+a. In step S+a, if the fuel pressure detected by the pressure sensor 35 has increased to a predetermined value or more, or if the fuel pressure detected by the pressure sensor 35 has been replaced, the other fuel pump 27
Determine whether the fuel discharge amount in (26) is within the normal value,
If this determination is YES, the process advances to step 52+. Further, when the determination is No, the same fuel pump 27 (26
) has decreased, and the fuel pump 27 (
26), and step S
's, the operation of the fuel F31 pump 27 (26) is stopped by cutting the power to the fuel pump 27 (26), etc., and then in step 820, the electromagnetic clutch @14 is turned off to stop the operation before supercharging. After stopping the operation of 15, the process proceeds to step S21. In step S2+, similarly to step S16, the engine load is determined by comparing the actual engine speed and intake air amount against the load characteristics of the engine 1 set according to the engine speed and intake air amount. It is determined whether or not the load is in a high load range equal to or higher than a second setting line, which is roughly higher than the first setting line. Here, if the determination is No, the control ends as is, while if the determination is YES due to the high load range of the engine 1.
When it is determined that end.

Therefore, in this embodiment, in step Sea in the above flow, the fuel pump 27 is driven in the high load range of the engine 1 based on the fuel pressure in the second fuel supply passage 23 detected by the pressure sensor 35. 26>
A discharge amount drop detection means 36 is configured to detect that the fuel discharge amount of the high flow rate pump (high flow rate pump communicating with the high flow rate injector 22) has decreased below a set value.

Similarly, in step 323, when the output of the discharge amount decrease detection means 36 is received and the fuel discharge amount of the fuel pump 27 (26) has decreased, the maximum amount of intake air filled into the working chamber 4 of the engine 1 is detected. A correction means 37 is configured to correct the filling ♀ to reduce it.

Therefore, in the above embodiment, the load state of the engine 1 is determined based on the engine speed and the intake air amount, and in the low and medium load range of the engine 1, the electromagnetic clutch @ structure 1
4, the supercharger 15 is kept in a stopped state, and intake air is supplied to the working chamber 4 of the engine 1 only from the main passage 6 in the intake passage 5. In addition, in the fuel supply system, the wide range injector 21 is driven, and only one of the two fuel pumps 26, 27, the fuel bong 726 (27>), which operates as a wide range pump, is driven. (27> The thus discharged fuel 11 passes through the first fuel 1 supply passage 23 and is supplied to the above-mentioned wide area injector 21, and directly from the injector 2'1 into the working chamber 4 of the engine 1. Jet-fed.

On the other hand, when the engine 1 shifts to a high load range, the electromagnetic clutch mechanism 1.1 is turned on and the supercharger 15 is activated.
As a result, intake air is supplied to the engine 1 not only through the main passage 6 but also through the supercharging passage 9. Also,
In addition to driving the wide area injector 21 and one fuel pump 26 (27) (wide area pump) as described above, the high flow rate injector 22 is driven, and the other fuel pump is operated as a high flow rate pump. 27 (26)
The fuel discharged from the fuel pump 27 (26) is supplied to the high flow injector 22 through the second fuel supply passage 24, and is injected from the injector 22 into the primary passage 7 of the main passage 6. and is indirectly supplied into the working chamber 4 of the engine 1.

At that time, each time the distance traveled by the vehicle is detected by the distance sensor 34 and the value reaches the set value,
By switching the two fuel switching valves 30 and 31, the fuel
One fuel pump 26 (27) of the pumps 26, 27 that was operating as a wide-area pump becomes a high-flow pump, and the other fuel pump 27 (26) that was operating as a high-flow pump becomes a wide-area pump. You can switch between them to suit. For this reason, the operating times (operating rates) of the two fuel pumps 26 and 27 become the same, and therefore the fuel pumps 26 and 27
The durability of the pumps 26, 27 can be improved.

While the other fuel pump 27 (26) (high flow pump) is in operation, the pressure of the fuel supplied from the pump 27 (26) to the high-flow injector 22 via the second fuel supply passage 24 is increased. is detected by the pressure sensor 35,
Based on the detected value of this pressure sensor 35, the fuel pump 2
7. It is determined whether the fuel r1 discharge amount in (26) has decreased below the set value. When this fuel discharge amount decreases, it is assumed that a failure has occurred in the fuel pump 127 (26), and at this time, the drive of the fuel pump 27 (26) is stopped and the N1a clutch machine side 14 is O
The FF operation is performed and the supercharger 15 is deactivated, thereby suppressing the intake air filling amount to the engine 1. However, when the discharge amount from the fuel pump 27 (26) as a high flow rate pump decreases and the amount of fuel injected from the high flow rate injector 22 decreases, the fuel injection rate of 9Am
In response to the decrease in the intake air-fuel ratio in the high load range of the engine 1, the intake air-fuel ratio to the engine 1 is suppressed by stopping the operation of the supercharger 15 and suppressing the charging amount. Over lean can be prevented. Therefore, the enriching effect of the exhaust gas purification device 20 provided in the exhaust passage 19 is ensured well, and the temperature thereof can be prevented from rising excessively.

(Second Embodiment) FIGS. 5 to 7 show the second embodiment. The same parts as in FIG. This is applied to an engine equipped with a machine.

That is, in this embodiment, as shown in FIG. 5, there is no supercharging passage 9 as in the first embodiment, and the intake passage 5' is connected to the primary passage 7' and the main passage 6 in the first embodiment. It has a secondary passage 8'. The intake passage 5' and the exhaust passage 19 intersect, and at the intersection, a turbine 38a and a blower 38b integrated with the turbine 38a are driven and rotated by the energy of the exhaust gas to supercharge the intake air. A turbo supercharger 38 is provided. 39 is
A wastegate valve that opens and closes the bypass passage 38C that bypasses the turbine 38a of the supercharger 38 to control the maximum supercharging pressure of the intake air supercharged by the supercharger 38, and this wastegate valve 39 serves as its actuator. The pressure chamber 40a of this diaphragm device 40 is connected to the intake passage 5' downstream of the blower 38b via a communication passage 41. Further, a solenoid valve 42 is disposed in the communication passage 41 to adjust the degree of dilution of the pressure (supercharging pressure) in the pressure chamber 40a of the diaphragm device 40 with atmospheric pressure.
The pressure chamber 40a of the diaphragm device 40 is controlled to open and close.
By adjusting the pressure, the opening degree of the waste l-gate valve 39 is adjusted to reduce the exhaust gas that bypasses the turbine 38a, thereby adjusting the supercharging pressure of the intake air by the blower 38b. There is.

Further, in this embodiment, a primary injector 433 is provided in the primary passage 7' of the intake passage 5', and a secondary injector 44 is provided in the secondary passage 8'. And these two injectors 43.4
4 are connected in series to each other by a communication passage 45, and communicated with the fuel tank 25' via a fuel supply passage 46 and a fuel return passage 47, and the fuel supply passage 46 has a fuel tank 25' with a Two fuel pumps 48 are provided, and a pressure sensor 35 is disposed downstream of each fuel pump 48 . The fuel supply passage 46 is provided with a fuel filter 49 for filtering the fuel flowing through the fuel supply passage 46.
and a pulsation damper 50 for smoothing discharge pulsations of the fuel discharged from the fuel pump 48. In addition, the fuel return passage 47 is provided with an injection 43 by adjusting the opening degree of the fuel return passage 47.
, 44 in accordance with the intake negative pressure downstream of the throwers 1 to 12 and 13 in the intake passage 5'.

The procedure for controlling the drive of the injectors 43, 44 and the fuel pump 48 using the control unit 32' will be explained with reference to FIG.
In the first step S1, the engine speed and the intake air detected by the air flow meter 11 are input, and in the next step S2, the fuel flow rate discharged from the fuel pump 48 and flowing into the injectors 43, 44 is set to "small". Determine whether it is a zone. This determination is made based on the actual engine speed and intake air amount detected in step S1 above, with respect to the load characteristics of the engine 1 that have been set in advance according to the engine speed and the intake air amount, as shown in FIG. This is done by comparing the When this judgment is YES,
Proceeding to step S3, the drive current of the fuel pump 48 is set to a current corresponding to the "small" fuel flow rate, and in step S4, the actual fuel pressure P is detected based on the output signal of the pressure sensor 35. Then, in step S5, the set value P1 corresponding to the case where the fuel flow rate is "small" is read from the memory, and then in step S6, the actual fuel pressure P is compared with the set value P1, and in the next step S7, the set value P1 is compared with the set value P1. Based on the comparison result, it is determined whether the fuel pressure P discharged from the fuel pump 48 is in a normal state as high as the set value P1.

When this determination is YES, and when the determination at step 5.32 is No, the process proceeds to step S8, and similarly to step S2, the fuel flow rate is determined to be "medium" by comparing with the characteristics shown in FIG. ” Determine whether it is in the zone.

If this determination is YES, proceed to step S9,
After setting the drive current of the fuel pump 48 to a current corresponding to the "medium" fuel flow rate, the actual fuel pressure P is detected again in step SIO based on the output signal of the pressure sensor 35, and then in step S! 1 and the fuel flow rate is "medium", the corresponding setting value P2 is read from the memory,
In step 312, the actual fuel pressure P and the set value P2 are compared in magnitude, and in the next step 813, the fuel pressure P discharged from the fuel pump 48 is determined based on the comparison result.
It is determined whether or not it is in a normal state where it is as high as the set value P2.

Roughly speaking, when the above judgment is YES, the above step S
When the determination in step 8 is No, the process proceeds to step 314, and similarly to step S2, it is determined whether the fuel flow rate is in the "large" zone by comparing with the characteristics shown in FIG.

If this determination is YES, the process proceeds to step S's, where the drive current of the fuel pump 48 is set to a current corresponding to the "large" fuel flow rate, and then the actual fuel pressure P is set again in step S's. Then, in step Say, the set value P3 corresponding to the case where the fuel flow rate is "large" is read from the memory, and in step S+a, the above-mentioned actual fuel
! The magnitude of I3+pressure P and set value P3 is compared, and in the next step 319, the fuel pump 48 is adjusted based on the comparison result.
It is determined whether the fuel pressure P discharged from the pump is in a normal state, which is as high as the set value P3.

Then, if it is determined as YES in this step S19,
When the determination in step Sr+ is No, the process proceeds to step 320, and the opening degree of the solenoid valve 42 is adjusted so that the waste gate valve 39 is opened and closed according to the supercharging pressure of the intake air, and the air is supplied to the engine 1. After controlling the boost pressure as usual, the process ends.

On the other hand, if the determination in step Syr313+819 is No, it is assumed that the fuel pressure P in the fuel supply passage 46 has not risen to the normal value due to a failure of the fuel pump 48, etc., and the process proceeds to step 32+. Then, the solenoid valve 42 was controlled to reduce the boost pressure supplied to the engine 1 by adjusting the opening so that the waste gate valve 39 was kept fully open regardless of the intake boost pressure. After that, finish.

Therefore, in this embodiment, step S7r of the above flow
Se3+ S19 constitutes a discharge amount reduction detection means 36' that detects that the fuel discharge amount of the fuel pump 48 has decreased below a set value.

Also, in step 32+, a correction means 37' is provided which corrects so as to reduce the maximum filling base of intake air filled into the working chamber 4 of the engine 1 when the fuel discharge amount of the fuel pump 48 decreases.

Therefore, in this embodiment, depending on the load state of the engine 1, the drive current of the fuel pump 48 is set to "large", "medium", "r"
/J controller, and the fuel discharge amount is adjusted in three stages, and as the load on the engine 1 increases, the fuel discharge amount increases.

During that time, the fuel pressure P corresponding to the above fuel discharge amount is
is detected by the pressure sensor 35, and when the fuel pressure P is different from the set values P1 to P3 set to correspond to the load state of the engine 1, it is detected by the fuel pump 48.
It was determined that this was due to a failure etc. of solenoid valve 4.
The waste gate valve 39 is held in the fully open state by adjusting the opening degree in step 2, thereby suppressing the intake air supercharging to the engine 1 by the turbo supercharging hole 38, and the air-fuel ratio of the intake air becomes equal to the fuel injection amount gA. The drop in temperature does not cause the exhaust gas purification device 20 to become overlean, thereby preventing an excessive temperature rise in the exhaust gas purification device 20.

In this second embodiment, when the fuel pressure P discharged from the fuel pump 48 decreases, the waste gate valve 39 is kept fully open and intake supercharging is stopped, thereby reducing the intake air charging L to the engine 1. ? However, a supercharging relief valve is provided in the intake passage 5' between the supercharger 38 and the intercooler 16 to open the intake passage 5' to the atmosphere or shut it off. When the fuel pressure P discharged from the fuel pump 4B decreases, the supercharging relief valve may be opened to stop intake supercharging.

Further, in each of the above embodiments, the fuel pumps 27 (26), 4
When the fuel discharge amount in No. 8 decreases, the intake supercharging amount is suppressed, but the present invention can also be applied to a normal naturally aspirated engine that does not perform intake supercharging. . In general, the present invention is of course applicable not only to the rotary piston engine 1 but also to other engines such as a reciprocating engine.

(Effects of the Invention) As explained above, according to the present invention, it is possible to detect that the set value of the fuel discharge amount has decreased due to a malfunction of the fuel pump, etc., and to respond to the decrease in the maximum intake air filling amount to the engine. By reducing and correcting the intake air, it is possible to suppress the intake air-fuel ratio from becoming over lean when the engine is under high load, thereby ensuring the normal enrichment effect of the engine exhaust purification device. This is something that can prevent excessive temperature rise.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of the present invention. 2 to 4 show a first embodiment of the present invention, FIG. 2 is a diagram of its physical structure, FIG. 3 is a flowchart showing the main routine of the processing procedure performed in the control unit, and FIG. is a flowchart showing a subroutine for switching the fuel pump. 5 to 7 show the second embodiment, FIG. 5 is a diagram equivalent to FIG. 2, FIG. 6 is a diagram equivalent to FIG. 3,
FIG. 7 is a characteristic diagram showing the fuel pump drive current switching characteristics with respect to the engine load condition. DESCRIPTION OF SYMBOLS 1... Engine, 4... Working chamber, 5.5'... Intake passage, 15.38... Supercharger, 19... Exhaust passage, 20... Exhaust purification device, 21, 22.43.44・
...Injector, 25.25'...Fuel tank, 2
6,27.48...Fuel pump, 32.32'...
Control [J-le unit, 35...pressure sensor, 36
．． 36'...Discharge amount drop detection means, 37.37'...
・Correction means, 39... waste gate valve, 42.
··solenoid valve.

Claims (1)

[Claims] (1) In an engine equipped with a fuel metering device that adjusts the amount of fuel supplied to a combustion chamber, and a fuel pump that supplies fuel in a fuel tank to the fuel metering device, the fuel discharge of the fuel pump a discharge amount drop detection means for detecting that the amount of discharge has decreased below a set value; and upon receiving the output of the detection means, when the fuel pump discharge amount decreases, the maximum amount of intake air to be filled into the combustion chamber is reduced. 1. A control device for an engine, comprising: an intake air filling amount correcting means for correcting the intake air filling amount.