JPH073215B2 - Engine fuel pump controller - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a fuel pump control device for an engine, and more particularly to a rotation control of a fuel pump according to operating conditions of the engine.

(Prior Art) Generally, in an engine based on fuel injection, a fuel pump is electrically driven at a constant rotation speed to discharge fuel, and a pressure relief valve operated by the intake pipe pressure is provided to reduce the intake pipe pressure. The discharge amount of the fuel pump is controlled to be constant by changing the relief amount according to the above. In such a configuration, since the rotation speed of the fuel pump is constant regardless of the operating state of the engine, the resistance due to the electric load relatively increases in the low rotation and low load regions where reduction of fuel is particularly required, Not only is it unfavorable in terms of fuel reduction, but there is a drawback that pump noise is audible when the engine noise is quiet, such as during idle operation.

Also, in low rotation speed and low load operation, a large amount of fuel is relieved by the pressure relief valve because the fuel consumption is small, but since this relief fuel circulates through the fuel pump, this fuel is consumed by the engine. There is a risk that the temperature rises due to the heat of, the error occurs in the fuel injection amount, and accurate air-fuel ratio control cannot be performed.

Therefore, it is conceivable that the rotation speed of the fuel pump is controlled according to the operating state of the engine, and the rotation speed of the fuel pump may be lowered in the low rotation and low load regions. For example, Japanese Patent Laid-Open No. 58-48765. Since the conventional fuel pump operation control device as disclosed in No. 1 is configured to simply reduce the number of revolutions of the fuel pump during idle operation, even if the pump noise during idle rotation can be reduced, It was impossible to precisely control the number of revolutions of the fuel pump according to the operating condition.

Also, the pressure of the fuel supplied from the fuel pump is detected,
A technique for controlling the discharge amount of the fuel pump so that the detected fuel pressure becomes equal to the preset fuel pressure based on the comparison between the detected fuel pressure and the preset fuel pressure is also known. However, the fuel pressure changes after the number of revolutions of the fuel pump changes, so that there is a problem that a response delay occurs in the control.

(Object of the Invention) In view of the above-mentioned circumstances, the present invention is capable of controlling fuel pressure with high responsiveness, and is capable of minimizing drive energy of a fuel pump according to an operating state of the engine. It is an object of the present invention to provide a control device of.

(Structure of the Invention) A control device for an engine fuel pump according to the present invention is
As shown in the figure, a control signal generating means for setting the rotational speed Rc of the fuel pump according to the operating state of the engine and generating a control signal representing the set rotational speed Rc, and control from the control signal generating means. Fuel pump drive means for receiving the signal to drive the fuel pump, fuel pump rotation speed detection means for detecting the rotation speed Rp of the fuel pump driven by the fuel pump drive means, and the fuel pump rotation speed detection means By comparing the detected rotation speed Rp and the set rotation speed Rc detected by, the rotation speed comparison determination means for determining whether or not the detected rotation speed Rp and the set rotation speed Rc, and the rotation speed By the number comparison and determination means, the detected rotation speed Rp and the set rotation speed Rc
If it is determined that the detected rotational speed Rp is the rotational speed correction means for correcting the rotational speed of the fuel pump so that the detected rotational speed Rp matches the set rotational speed Rc, the rotational speed comparison and determination means detects the detected rotational speed Rp. When it is determined that the rotational speed Rp and the set rotational speed Rc match, the fuel pressure detection means for detecting the pressure Fp of the fuel supplied from the fuel pump, and the detected fuel pressure detected by the fuel pressure detection means. By comparing Fp and a preset fuel pressure Fc, the fuel pressure comparison determination means for determining whether or not the detected fuel pressure Fp and the set fuel pressure Fc match, and the fuel pressure comparison determination means When it is determined that the detected fuel pressure Fp and the set fuel pressure Fc are different, the detected fuel pressure Fp is the set fuel pressure Fc.
And a fuel pressure correction means for correcting the fuel pressure so that

(Effects of the Invention) According to the present invention, focusing on the rotational speed of the fuel pump, which has a quicker change response than the fuel pressure, feedback control of the pump rotational speed is first performed to set the pump rotational speed Rp to the set rotational speed Rc.
Since the fuel pressure feedback control is performed after the fuel pressure feedback control is performed, the responsiveness of the fuel pressure feedback control can be improved.

Further, simply by performing feedback control of the pump rotation speed, even if the pump rotation speed Rp matches the set rotation speed Rc, there is a possibility that the fuel pressure may vary due to the variation in the performance of the fuel pump. According to the present invention, since the fuel pressure feedback control is performed after the pump rotation speed feedback control, it is possible to prevent variation in fuel pressure due to variation in fuel pump performance.

Furthermore, according to the present invention, not only can pump noise during idle operation of the engine be reduced, but also drive energy of the fuel pump can be minimized. It is possible to reduce the fuel consumption. Also, the amount of fuel relief through the pressure relief valve is reduced,
It is possible to prevent the temperature rise of the fuel due to a large amount of fuel being relieved and circulated as in the conventional case. Therefore, there is an advantage that an error of the fuel injection amount can be eliminated and an accurate air-fuel ratio control can be secured. .

(Examples) Examples of the present invention will be described in detail below with reference to the drawings.

FIG. 2 is a structural explanatory view of an embodiment of the present invention. The engine 1 includes a piston 2, a high load intake port 3a, a low load intake port 3b, an exhaust port 4, an intake valve 5, an exhaust valve 6 and the like. Is equipped with. The intake system of the engine 1 is of a fuel injection type, and the flow rate of the air sucked from the air cleaner 7 into the intake passage 8 is detected by an air flow meter 9 and introduced into the intake ports 3a and 3b through a throttle valve 10. The fuel atomized and injected from the fuel injection valve 11 provided in the intake port 3a is mixed with air and supplied to the combustion chamber.
The injection amount of fuel injected from the fuel injection valve 11 is the intake air amount Qa detected by the air flow meter 9, the opening degree of the throttle valve 10 detected by the throttle sensor 12, and the engine speed obtained from the engine 1. Ne is used as a basic input, and an output signal from an O ₂ sensor 14 provided in the exhaust passage 13 is used as a feedback signal, which is controlled by a controller 15 including a microcomputer. Reference numeral 16 is a catalyst provided in the exhaust passage 13, and 17 is a valve that closes the high load intake port 3a.

On the other hand, the fuel in the fuel tank 18 is supplied to the fuel pump 20 through the oil supply pipe 19, and the fuel discharged from the fuel pump 20 is supplied to the fuel injection valve 11 through the filter 21. And excess fuel is pressure relief valve 22 and relief passage
It is returned to the upstream side of the fuel pump 20 through 23. Also,
The controller 15 feedback-controls the rotation speed of the fuel pump 20 via the fuel pump drive circuit 24, and further corrects the rotation speed of the fuel pump 20 by a signal obtained from the fuel pressure sensor 25.

The above is an example of the configuration of the fuel pump control apparatus according to the present invention. Next, the operation will be described with reference to the flowchart of FIG. 3 showing the control processing executed by the controller 15.

In FIG. 3, first, at step 31, it is determined whether or not the ignition is ON, and if YES, the routine proceeds to step 32, at which a signal indicating the intake air amount Qa obtained from the air flow meter 9 and the engine speed obtained from the engine 1 are obtained. Input the signal that represents Ne. Next, at step 33, a preset injection map is read to determine the basic injection pulse width, that is, the basic injection amount. Then step 34
In the above, the fuel pump 20 command rotational speed Rc is set based on the basic injection pulse width, and a signal representing the command rotational speed Rc is output to the fuel pump drive circuit 24 as a basic control signal of the fuel pump 20. Is driven (step 35). Next, in step 36, the signal representing the rotational speed Rp output from the fuel pump 20 is read, and in step 37 Rp
Is equal to Rc, and if NO, it is further determined in step 38 whether Rp is larger than Rc. If Rp> Rc, the rotation speed of the fuel pump 20 is decreased in step 39, and if Rp <Rc, the rotation speed of the fuel pump 20 is increased in step 40, and the process returns to step 35.

On the other hand, if the determination result in step 37 is Rp = Rc, the fuel pressure Fp output from the fuel pressure sensor 25 in the next step 41.
Read the signal that represents
It is compared whether or not this detected fuel pressure Fp is equal to the preset fuel pressure Fc. If the decision result in the step 42 is NO, the process advances to a step 43.
If Fp <Fc, the rotation speed of the fuel pump 20 is increased in step 40. If Fp> Fc, the pressure relief valve 22 is activated in step 44 to reduce the fuel pressure, and the process proceeds to step 35.
Return to.

Next, when the determination result in step 42 is Fp = Fc, the routine proceeds to step 45, where it is determined whether or not the intake air change amount ΔQa is larger than a preset intake air change amount ΔQb,
If YES, in step 46, the command rotational speed Rc is multiplied by a predetermined proportional constant K. The processing in steps 45 and 46 is performed in order to immediately increase the fuel pressure to, for example, the fuel pressure when the engine is fully opened at the time of sudden acceleration.
It is a process to forcibly increase the rotation of 20. If the determination result of step 45 is NO, that is, if ΔQa ≦ ΔQb, the process returns to step 32.

Next, FIG. 4 shows calculated values of intake air amount Qa and fuel pump speed.
3 is a time chart showing the relationship between Rc, fuel pressure Fp, a correction amount by feedback, and the rotational speed Rp of the fuel pump 20, in which the basic control signal representing Rc shows the steps in FIG. Fuel pump at 40
It shows a state in which the rotational speed is increased by 20 and the pressure relief valve is operated in step 44, whereby the rotational speed of the fuel pump is corrected.

As is clear from the above description, according to the embodiment of the present invention, the rotation speed Rp of the fuel pump 20 is feedback-controlled according to the injection pulse width, and further correction-controlled according to the change of the fuel pressure Fp. Therefore, it is possible to improve the responsiveness of the feedback control of the fuel pressure, and it is also possible to prevent the variation in the fuel pressure due to the variation in the performance of the fuel pump 20. Further, it becomes possible to minimize the driving energy of the fuel pump 20.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of the present invention, FIG. 2 is an explanatory diagram of the configuration of an embodiment of the present invention, FIG. 3 is a flowchart of processing by the controller of the embodiment of FIG. 2, and FIG. It is explanatory drawing explaining operation | movement of an example. 1 ... Engine, 11 ... Fuel injection valve 15 ... Controller, 18 ... Fuel tank 20 ... Fuel pump, 22 ... Pressure relief valve 23 ... Relief passage, 24 ... Fuel pump drive circuit

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Masashi Maruhara 3-1, Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Co., Ltd. (56) Reference JP-A-57-108427 (JP, A)

Claims (1)

[Claims] 1. A control signal generating means for setting a rotational speed Rc of a fuel pump according to an operating condition of an engine and generating a control signal representing the set rotational speed Rc, and a control signal from the control signal generating means. Receiving the fuel pump, driving the fuel pump, fuel pump driving means driven by the fuel pump driving means, the fuel pump rotation speed detecting means for detecting the rotation speed Rp, and the fuel pump rotation speed detecting means. A rotation speed comparison / determination unit that compares the detected rotation speed Rp with the set rotation speed Rc to determine whether the detected rotation speed Rp and the set rotation speed Rc match, When it is determined by the number comparison and determination means that the detected rotation speed Rp and the set rotation speed Rc are different, the rotation speed of the fuel pump is corrected so that the detected rotation speed Rp matches the set rotation speed Rc. Rotation speed correction means When the rotation speed comparison and determination means determines that the detected rotation speed Rp and the set rotation speed Rc match, a fuel pressure detection means that detects a pressure Fp of fuel supplied from a fuel pump, Detected fuel pressure Fp detected by the fuel pressure detection means
And a preset fuel pressure Fc are compared with each other to determine whether or not the detected fuel pressure Fp and the set fuel pressure Fc are coincident with each other, and fuel pressure comparison and determination means, and the fuel pressure comparison and determination. By means, when it is determined that the detected fuel pressure Fp and the set fuel pressure Fc are different, a fuel pressure correction unit that corrects the fuel pressure so that the detected fuel pressure Fp matches the set fuel pressure Fc, A fuel pump control device for an engine, comprising: