JP2567320Y2 - Fuel supply device for internal combustion engine - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel supply device for an internal combustion engine, and more particularly to a fuel supply device configured to drive and control a fuel pump based on a fuel supply pressure value. Technology to avoid the effects of

[0002]

2. Description of the Related Art Conventionally, in an electronically controlled fuel injection device for an internal combustion engine, the amount of fuel supplied to the engine is controlled by the opening control time of a fuel injection valve. In such a fuel injection device, if the pressure difference between the fuel supply pressure to the fuel injection valve and the intake pressure near the injection hole of the fuel injection valve is not constant, a constant fuel corresponding to the valve opening time of the injection valve is generated. It cannot be supplied. Therefore, the suction negative pressure on the downstream side of the throttle valve is supplied to a reference pressure chamber of a pressure regulator for adjusting a supply pressure (hereinafter, simply referred to as “fuel pressure”) of the fuel pumped from the fuel pump to the fuel injection valve. When the pressure difference between the pressure in the reference pressure chamber and the supply pressure from the fuel pump, that is, the pressure difference between the suction pressure and the fuel pressure of the injection hole portion is equal to or higher than a predetermined value, a return passage for returning fuel to the fuel tank is formed. When opened, the differential pressure is kept constant (see Japanese Patent Application Laid-Open No. 60-212634).

[0003] In the above-described fuel supply device, it is necessary to keep the pressure difference constant even if the required fuel amount increases suddenly. Therefore, the fuel pump is driven with a load larger than necessary. The fuel pump discharges a larger amount of fuel than necessary, and the excess supplied fuel is returned from the pressure regulator to the fuel tank as surplus fuel.

Further, in order to reduce the return fuel amount as much as possible and to reduce the load on the fuel pump, the discharge amount of the fuel pump is controlled based on the operating conditions of the engine corresponding to the required fuel amount of the engine. However, in this case, too, the discharge amount is set to be large so as to absorb the change in the discharge amount due to the variation or deterioration of the fuel pump, and the generation of excess fuel cannot be avoided.

On the other hand, as a technique for avoiding generation of surplus fuel, a sensor for detecting a fuel supply pressure in a fuel supply passage is provided, and a fuel pump is provided at the fuel pressure detected by the sensor so as to obtain a desired differential pressure. There is a system configured to control the discharge amount of the fuel pump so that the discharge amount of the fuel pump corresponds to the required fuel amount of the engine, thereby suppressing the generation of excess fuel.

[0006]

However, in the system in which the detection result of the fuel pressure is fed back to the discharge amount control of the fuel pump as described above, the fuel pressure maintains a constant pressure difference from the fuel pressure in the collector portion of the intake pipe. As shown in FIG. 4, the intake pulsation inside the collector and the injection pulsation of the fuel injection valve are added especially during the steady operation, and the value becomes different from the actual required fuel pressure value. There is a problem that the discharge amount control of the fuel pump cannot be performed.

Therefore, the present invention has been made in view of such a conventional problem, and prevents the influence of pulsation such as intake pulsation and injection pulsation of a fuel injection valve during steady operation, thereby stably controlling the fuel discharge amount. It is an object of the present invention to provide a fuel supply device for an internal combustion engine capable of performing the following.

[0008]

SUMMARY OF THE INVENTION Therefore, the present invention provides a fuel injection valve for injecting fuel into an intake pipe of an engine, a fuel pump for pumping fuel to the fuel injection valve, and a fuel injection valve from the fuel pump. A fuel supply pressure detecting means for detecting a supply pressure of the fuel fed to the intake pipe as a differential pressure with respect to the intake negative pressure in the intake pipe, and a corrected pressure value obtained by weighted averaging the fuel supply pressure value detected by the fuel supply pressure detecting means. Correction pressure value calculation means to be sought, steady operation state detection means for detecting the steady operation state of the engine, and when the steady operation state of the engine is detected,
The correction pressure value calculated by the weighted average by the correction pressure value calculation means is kept constant, and the fuel supply pressure detected by the fuel supply pressure detection means is kept constant in other transient operation states. And a fuel pump control means for controlling a discharge amount of the fuel pump.

[0009]

According to this configuration, during steady operation of the engine,
Since the discharge amount of the fuel pump is controlled based on the corrected pressure value obtained by weighting and averaging the fuel supply pressure value by the corrected pressure value calculating means, it is possible to eliminate the influence of fuel pressure fluctuation due to intake pulsation and fuel injection valve pulsation. Therefore, it is possible to stably control the discharge amount of the fuel pump with a value close to the actual fuel pressure.

In the transient operation, the corrected pressure value obtained by weighted averaging is not used, and the actual fuel supply pressure value detected by the fuel supply pressure detecting means is used as it is. Discharge amount control can be performed.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. In FIG. 2 showing the configuration of one embodiment, fuel in a fuel tank 1 is sucked by a fuel pump 2, and fuel discharged from the fuel pump 2 is pumped to each fuel injection valve 4 via a fuel supply passage 3. Is done.

The fuel injection valve 4 is an electromagnetic fuel injection valve that is energized to open, is energized, is deenergized, and closes. The fuel injection valve 4 corresponds to an engine required fuel amount sent from a control unit 7 described later. Valve opening is controlled in accordance with a drive pulse signal having a predetermined pulse width Ti (valve opening time), and fuel is injected and supplied into an intake pipe downstream of a throttle valve of an engine (not shown).

A fuel filter 5 is provided in the fuel supply passage 3.
And a fuel pressure sensor 6 as fuel supply pressure detecting means for detecting a fuel supply pressure (fuel pressure) PF near the fuel injection valve 4 as a differential pressure with respect to an intake negative pressure in an intake pipe (collector section). Is provided. The fuel pressure PF detected by the fuel pressure sensor 6 is sent to a control unit 7 for controlling the driving of the fuel pump 2, and the voltage VFP applied to the fuel pump 2 is adjusted based on the fuel pressure PF. .

The control unit 7 includes a CPU,
A microcomputer including a ROM, a RAM, an A / D converter, an input / output interface, and the like;
In addition to the detection signal from the fuel pressure sensor 6, it receives input signals from various sensors, calculates the fuel injection amount based on the input signals, and controls the driving of the fuel pump 2. As the various sensors, an air flow meter 8 is provided in an intake duct (not shown).
And outputs a signal corresponding to.

A crank angle sensor 9 is provided, and a reference angle signal REF for each reference angle position (in this embodiment, for each TDC) and a unit angle signal POS for each 1 ° or 2 °.
Is output. Here, the engine rotation speed Ne can be calculated by measuring the cycle of the reference angle signal REF (TDC cycle) or the number of occurrences of the unit angle signal POS within a predetermined time.

Then, the control unit 7 calculates a basic injection pulse width Tp (basic valve opening time) corresponding to the required fuel amount of the engine based on the intake air flow rate Q and the rotational speed Ne. Various correction coefficients COEF are set from information such as Tw, and the basic injection pulse width Tp is corrected with various correction coefficients COEF and the like to set a final injection pulse width Ti. By outputting a drive pulse signal having the injection pulse width Ti to the fuel injection valve 4 at a predetermined timing, the fuel corresponding to the request of the engine can be intermittently supplied to the engine by the valve opening control time of the fuel injection valve 4. To be supplied.

Here, as described above, in order to control the injection amount by the opening time of the fuel injection valve 4, it is necessary to control the fuel pressure PF so that the differential pressure with respect to the intake negative pressure becomes constant. For this purpose, the control unit 7 determines the required discharge amount of the fuel pump 2 and controls the voltage applied to the fuel pump 2 based on the discharge amount. still,
In this embodiment, the control unit 7 has functions as a correction pressure value calculation unit and a fuel pump control unit as shown in the flowchart of FIG.

Next, the discharge amount control of the fuel pump 2 according to the present embodiment will be described with reference to the flowchart of FIG. First, in step 1 (hereinafter referred to as “S1”), the voltage value VPB detected by the fuel pressure sensor 6 is read. Next, in S2, the detected voltage value VPB is changed to the fuel pressure PIN.
Convert to J.

In S3, it is determined whether or not the operating state of the engine is in a steady operating state. That is, specifically, the determination is made based on whether or not the fluctuation amount of the rotation speed Ne obtained from the signal from the crank angle sensor 9 is within a predetermined range. If the engine is in the steady operation state, the process proceeds to S4, and if the engine is in the transient operation state, the process proceeds to S5 and below, and the discharge amount of the fuel pump 2 is controlled based on the fuel pressure PINJ before weighted averaging in S4.

In S4, the fuel pressure PIN newly obtained in S2
And J _NEW, and the weighted average of the fuel pressure Pinj _old obtained in previous, after calculating the corrected fuel pressure Pinj _ave, the process proceeds to S5. In S5, comparing the computed corrected fuel pressure Pinj _ave a predetermined value, the fuel pump 2 in the direction toward the predetermined value
Of the fuel pump 2 is controlled by increasing the applied voltage VFP. That is, the predetermined value is a constant fuel pressure value for obtaining a desired differential pressure. If the differential pressure changes, the injection amount obtained with respect to the valve opening time of the fuel injection valve 4 changes. Since the injection amount cannot be controlled with high accuracy through the opening time of the fuel injection valve 4, the voltage VFP applied to the fuel pump 2 is controlled to keep the fuel pressure constant so that a desired differential pressure can be obtained. Is what you do.

Specifically, if the corrected fuel pressure PINJ _ave is larger than the predetermined value, the process proceeds to S6, in which the applied voltage VFP is reduced by a predetermined value ΔV so as to reduce the fuel pressure PF, and the corrected fuel pressure PINJ _{ave is} reduced. Is smaller than the predetermined value, the process proceeds to S7, and the applied voltage VFP is increased by a predetermined value ΔV in order to increase the fuel pressure PF. And
Set applied voltage VFP based on a comparison between the corrected fuel pressure Pinj _ave and the predetermined value is actually applied to the fuel pump 2 in the next S8.

As described above, by selectively controlling the discharge amount of the fuel pump 2 in accordance with the operating state of the engine, good responsiveness of the control can be obtained during the transient operation of the engine, and at the same time, during the steady operation of the engine. Since the influence of the fuel pressure fluctuation due to the intake pulsation and the injection pulsation of the fuel injection valve 4 can be eliminated, the discharge amount of the fuel pump 2 can be controlled more stably with a value close to the actual fuel pressure.

In the present embodiment, a sensor capable of detecting the fuel supply pressure as a differential pressure from the intake negative pressure in the intake pipe is used.
The fuel supply pressure and the intake negative pressure may be separately detected by a sensor, and a difference between the respective values may be taken to detect the differential pressure.

[0024]

[Effects of the Invention] As described above, according to the present invention,
When the steady operation state of the engine is detected, the corrected pressure value weighted and averaged by the corrected pressure value calculation means is kept constant, and in other transient operation states, the corrected pressure value is detected by the fuel supply pressure detection means. Fuel pump control means for controlling the discharge amount of the fuel pump so as to maintain the fuel supply pressure constant, it is possible to selectively control the discharge amount of the fuel pump according to the operating state of the engine, During transient operation of the engine, good responsiveness of control can be obtained, and during steady operation of the engine, the influence of fuel pressure fluctuation due to intake pulsation and fuel injection valve pulsation can be eliminated. Accordingly, stable control of the discharge amount of the fuel pump can be performed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a fuel supply device according to the present invention.

FIG. 2 is a system diagram showing the overall configuration of the fuel supply device according to the present invention.

FIG. 3 is a flowchart for explaining a discharge amount control of the fuel pump according to the present invention.

FIG. 4 is an explanatory diagram for explaining a conventional example.

[Explanation of symbols]

 Reference Signs List 1 fuel tank 2 fuel pump 3 fuel supply passage 4 fuel injection valve 5 filter 6 fuel pressure sensor 7 control unit 8 air flow meter 9 crank angle sensor

Claims (1)

(57) [Scope of request for utility model registration] 1. A fuel injection valve for injecting fuel into an intake pipe of an engine, a fuel pump for pumping fuel to the fuel injection valve, and a supply pressure of fuel supplied from the fuel pump to the fuel injection valve in an intake pipe. Fuel supply pressure detecting means for detecting a pressure difference with respect to the intake negative pressure of the engine, correction pressure value calculating means for obtaining a weighted average of the fuel supply pressure values detected by the fuel supply pressure detecting means, and a steady state of the engine. A steady-state operating state detecting means for detecting an operating state; and when the steady-state operating state of the engine is detected, the corrected pressure value averaged by the weighted average by the corrected pressure value calculating means is kept constant. And a fuel pump control means for controlling the discharge amount of the fuel pump so as to keep the fuel supply pressure detected by the fuel supply pressure detection means constant in the transient operation state of The fuel supply apparatus for an internal combustion engine characterized by and.