JPS6047838A - Fuel-pressure controlling apparatus for fuel injection type internal-combution engine - Google Patents

Abstract

PURPOSE:To improve the starting and driving performance of an engine, by controlling the fuel injection pressure appropriately and preventing generation of fuel vapor by raising the level of the set pressure of a fuel pressure regulator at the time of high-temperature starting of the engine and lowering the set pressure gradually after starting of the engine. CONSTITUTION:A control apparatus of this invention comprises a regulator 8 which controls the pressure of fuel supplied from a fuel pump to a prescribed value. The regulator 8 returns a part of fuel via a return passage 12 by opening and closing a valve body 21 by the aid of a diaphragm 20 according to the fuel pressure and the resultant pressure of the force of a spring 11 disposed in a vacuum chamber 9 and the negative pressure of intake air introduced via a vacuum passage 12. Here, an electromagnetic vacuum control valve 18 is provided in a relief passage 23 branched from the vacum passage 19. By means of a control circuit 28, to which outputs of a starter switch 15 and sensors 24, 25, 27 for detecting the quantity of intake air, the engine speed and the fuel pressure, respectively, are furnished, the vacuum control valve 18 is controlled to lower the level of negative pressure introduced to the regulator 8 at the time of high- temperature starting of the engin and to cancel the above pressure reduction gradually after starting of the engine.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a combustion pressure control device for a fuel-injected internal combustion engine.

<Conventional technique (Ho)) Injecting and supplying fuel No. 31 from the injection valve to the intake pipe J,
In such an engine, the injection amount can be easily controlled by always keeping constant Bl:l between the injection Q/J pressure and the intake pipe pressure (intake negative pressure). If you try to start the engine again when the engine temperature is quite high after hours of operation, the heat in the engine compartment will overheat the fuel piping, causing the fuel temperature to rise and vapor to rise. This is likely to occur and may interfere with fuel injection.

Figure 1 shows a conventional device that suppresses the generation of vapor by increasing the fuel pressure when the engine runs at high fuel consumption. 1 is installed in the intake pipe, 2 is installed in the intake pipe 1 3 is the fuel tank.
(Refer to Publication No. 94436, etc.) A fuel pump 5, a fuel damper 6, a filter 7, and a pressure regulator 8 are interposed in the middle of the fuel pipe 4 that connects the fuel injection valve 2 and the fuel tank 3. ．． The pressure of the fuel pressure-fed from sl is regulated to a predetermined pressure by a pressure regulator 8, and then supplied to the fuel injection valve 2.

During normal operation, engine suction negative pressure is introduced into the angular pressure air 9 of the pressure regulator 8 through the three-way solenoid valve 10, and when the fuel pressure in the pipe 4 exceeds the combined pressure of the suction negative pressure and the spring 11. , the return passage 12 releases a portion of the fuel from the oil tube 13 to the fuel tank 3, and the differential pressure between the fuel pressure (injection pressure) and the suction negative pressure is maintained constant.

When the engine starts at a high temperature, the water temperature sensor 14 and starter switch 15 detect engine cooling water temperature, etc.
The three-way solenoid valve 10 is switched by the control circuit 16 based on the signals from the three-way solenoid valve 10, and the angular pressure constriction 9 of the pressure regulator 8 is opened.

As a result, the set pressure of the pressure regulator 8 increases and the fuel pressure reaches its maximum level, thus preventing the generation of vapor at the time of high-temperature startup, and ensuring a predetermined injection force from the fuel injection valve 2.

However, with such conventional devices, the fuel pressure is set to the maximum when the engine is started at high temperature, and after a predetermined time after starting, the fuel pressure is switched and set according to the intake negative pressure. Therefore, when the engine starts idling after starting, the injection pressure is suddenly lowered due to the low suction negative pressure during idling. For this reason, although the startability of the engine at high temperatures is maintained well,
When the fuel pressure is changed, the 1lF1 law claw suddenly changes, causing a shock due to torque fluctuations, etc., which causes problems during operation after startup.

(Objective of the Invention) The object of the present invention is to maintain good drivability by avoiding such sudden changes in fuel pressure.

(Structure d5 and operation of the invention) The present invention includes means for detecting engine operating conditions, an injection control circuit that calculates a fuel injection level based on the detected value and outputs an injection signal, and an injection control circuit that is opened and closed by this injection signal. A pressure regulator that sets the fuel pressure supplied to the fuel injection valve according to the engine suction negative pressure, and a negative pressure control valve that controls the negative pressure introduced to the pressure regulator to reduce the pressure. On the other hand, there is a means for detecting the fuel temperature in the fuel pipe 31 in the engine room, a means for detecting engine starting, and a means for detecting the basic fuel pressure in advance in accordance with the pulse width of the injection signal and the engine rotation speed. a correction storage section that stores in advance a correction coefficient corresponding to the fuel temperature and the elapsed time after engine startup; and a correction storage section that stores the negative pressure introduced into the pressure regulator in accordance with these stored values. An arithmetic control circuit that operates the negative pressure control valve is installed, and the 9f7 of the engine with high fuel temperature is provided.
Jz reduces the negative pressure introduced into the pressure regulator when the engine is started, and gradually releases the reduced pressure of the negative pressure introduced after starting.
control the sea urchins.

In other words, when starting the engine at a high temperature, the set pressure of the breath regulator is increased to bring the fuel pressure to almost the maximum to suppress the generation of vapor. Gradually lower the constant pressure of the pressure regulator while adjusting the width (corresponding to the load) and rotation speed.

Therefore, the fuel pressure does not drop to zero after starting, and is smoothly switched to the fuel pressure value corresponding to the suction negative pressure in the operating state at that time. As a result, the occurrence of fluctuations of 1 to 1 lux due to VJ changes in fuel pressure can be sufficiently prevented.

(Example) Figures 2 and 3 show an example of the present invention, and are an overall configuration diagram and a control block diagram, in which 17 is an engine body, 1 is an intake pipe,
2 is a fuel injection valve, 3 is a fuel tank, 5 is a fuel pump, 6
7 is a fuel damper, 7 is a fuel filter, 8 is a breather regulator, and 18 is a negative pressure control valve.

In the pressure regulator 8, as in FIG. A valve body 21 attached to a diaphragm 20 responds when the combined pressure with the engine intake negative pressure introduced into the engine is exceeded.
hears the return passage 12, and releases a part of the fuel in the fuel pipe 4 from the oil chamber 13 to the fuel tank 3, regulating the fuel pressure to a predetermined value.

Further, the negative pressure control valve 18 is a solenoid valve, which is installed in the popular passage 23 that connects the upstream side of the throttle valve 22 to the negative pressure passage 19, and is connected to one -C negative pressure passage according to the quantity valve ratio. The inflowing atmospheric air dilutes and reduces the suction negative pressure introduced into the negative pressure chamber 9 of the pressure regulator 8.

On the other hand, 24 is an intake level sensor as a means for detecting engine operating conditions, 25 is also a rotation sensor, ζ14 (built in the distributor 26) is a water temperature sensor that detects the engine cooling water temperature, and 27 is a rotation sensor. fuel pipe 4
A fuel temperature sensor (in the figure, it is installed in the oil chamber 13 of the pressure regulator 8) is a means for detecting the fuel temperature in the engine, and 15 is a starter switch as a means for detecting engine starting. The signal is sent to control circuit 28.

The control circuit 28 includes an injection control circuit 29 that calculates the amount of fuel to be injected based on the intake set signal and the rotational speed signal, and outputs an injection signal to the fuel injection valve 2. A fuel pressure storage unit 30 that stores basic fuel pressure values in advance, a correction storage unit 31 that stores correction coefficients in advance corresponding to the fuel temperature in the fuel pipe 4 and the elapsed time after engine startup; The pressure is introduced into the negative pressure chamber 9 of the pressure regulator 8 according to the stored value of [1 standard negative L -
and a calculation control circuit 32 which calculates the negative pressure control valve 18 and opens and closes the negative pressure control valve 18.

In this case, as shown in FIG.
I! A basic fuel pressure value (expressed as a control value) is stored, which becomes a smaller value as the pulse width P of the four-sword signal and the rotational speed N increase, and the correction storage unit 31 stores, as shown in FIG.
A correction coefficient that becomes smaller as the fuel temperature S becomes smaller and the elapsed time t after engine startup becomes longer is stored.

The arithmetic control circuit 32 receives a time signal from a timer 33 that starts counting time when the starter switch 15 is turned on;
Correction storage section 3 according to the fuel temperature signal from fuel temperature sensor 27
1, and at the same time read the corresponding basic fuel pressure value from the fuel pressure storage unit 30 according to the pulse width of the injection signal and the rotation speed signal from the rotation sensor 25. The negative pressure introduced into the threshold 1 fregulator 8 is calculated from the negative pressure, and the negative pressure control valve 18 is driven to open and close so that the target negative pressure is achieved.

Specifically, the correction coefficient is 0.8, and the basic fuel pressure value is 0.3 (
(see Figures 4 and 5), multiply these by 0.
8X0.3=0.24, and set the negative pressure control valve 18 so that the calculated value 0124 becomes the quantity valve ratio of the negative pressure control valve 18.
The duty is controlled at a predetermined frequency. In this case, if both the correction coefficient and the basic fuel pressure value are 1, the negative pressure control valve 18 is fully opened, closed as it approaches 0, and fully closed when either of them reaches 0.

J: Ru flow I in the above configuration? -1~ as shown in FIG. 6, it is first determined at 101 whether the engine is to be started, and once the engine has started, the elapsed time [1~] starts to be counted at 102.

Next, at 103, fuel humidity 81 rotation speed N, injection QJ pulse width P1 elapsed time [is detected, and based on these values '1
At 04, the basic fuel pressure value and correction coefficient are read out, and
At step 105, its peak V (which becomes the quantity valve ratio of the negative pressure control valve 18) is calculated.

If this ram is O, go to 106 to 107, and if it is other than 0, go to 108 and go to the f1 pressure control valve 18 based on the canopy V.
The control value of is determined.

Then, a control signal 109 for duty-controlling the negative pressure control valve 18 is output, and the process is repeated until the product V or O is reached.

As a result, the pressure V regulator 8 can be adjusted according to each condition.
The suction negative pressure introduced into the negative pressure chamber 9 of the engine is controlled to be reduced (that is, when starting the engine with high fuel temperature, both the injection pulse width and the rotational speed are at a minimum), the negative pressure control valve 18 is almost fully opened, and the pressure regulator is closed. The negative pressure introduced into the breath regulator 8 is maintained at approximately atmospheric pressure, and the set pressure of the breath regulator 8 is increased.

Therefore, the fuel pressure is set to almost the maximum, and it is possible to sufficiently prevent the generation of vapor during high-temperature starting, thereby ensuring good startability.

After this start, the fuel temperature, elapsed time and rn
The negative pressure control valve 18 is driven in accordance with the operating conditions of pulse width and rotational speed, and the reduction in the negative pressure introduced into the pressure regulator 8 is sequentially released.

Therefore, the set pressure of the pressure regulator 8 is gradually lowered, and the fuel pressure is lowered in accordance with each condition, and when the pressure reduction is finished, the intake is returned to the next operating state. This allows a smooth transition to a fuel pressure value that is compatible with the negative pressure.

Therefore, it is possible to avoid a situation where the set pressure of the prefuge 1 fregulator 8 suddenly changes after the engine is started from a high temperature state as in the conventional example, and the fuel pressure suddenly changes.
As a result, a stable injection pressure can be maintained and fuel injection can be performed satisfactorily, resulting in smooth drivability.

In addition, when starting an engine with a low fuel temperature (1-5, the negative pressure control valve 18 is also used to some extent, but since the pressure for each combustion increases by that amount, the atomization of the injected fuel can be improved). Later, during normal operation, the negative pressure control valve 18 is fully closed and the fuel pressure horn is controlled so that the differential pressure with the suction negative pressure is constant, so that the fuel injection regulation is controlled from the low speed and low load range to the high speed and high load range. It is possible to accurately control W1 of IJ.

(Effects of the invention) When the engine is started at a high temperature, the fuel pressure can be reduced to prevent the generation of vapor, and after the engine has been started, the fuel pressure can be smoothly switched to control the injection pressure to an appropriate level. This has the effect of improving startability and drivability.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of the main parts of a conventional example, FIGS. 2 and 3 are a dimensional overall configuration diagram and control block diagram of an embodiment of the present invention, and FIG.
Figure 5 is a map showing an example of setting the base fuel pressure correction coefficient.
FIG. 6 shows flower 1-. 1... Intake pipe, 2... Fuel @ side valve, 4... Fuel pipe, 5... Fuel pump, 8... Pressure regulator, 14... Water temperature sensor, 15... Starter switch (means for detecting start), 18... negative pressure control valve;
24...Intake hinge (Its that detects operating conditions)
), 25... Rotation sensor, 27... Fuel temperature sensor, 2
8...control circuit, 29...r@sword sub-control circuit 30.
...9&i pressure storage section, 31...correction storage section, 32...
・Arithmetic control circuit. Figure 4 Figure 5 Zuran P+5 Meng Eaves S →

Claims (1)

[Claims] means for detecting engine operating conditions; an injection control circuit that calculates fuel injection quantity based on the detected value and outputs an injection signal; and a fuel injection valve that is opened and closed in accordance with the injection signal;
It is equipped with a pressure regulator that sets the fuel pressure supplied to the fuel injection valve at -C depending on the intake negative pressure of the engine, and a negative pressure control valve that reduces the negative pressure introduced into the pressure regulator. A means for detecting the fuel temperature in the fuel pipe in the room, a means for detecting engine start, and a fuel pressure storage section that stores a base fuel pressure value in advance in accordance with the pulse width of the jet engine and the engine rotation speed. and,
a correction storage unit that stores correction coefficients in advance in accordance with the fuel temperature and the elapsed time after starting the engine; and a correction storage unit that calculates a negative pressure to be introduced into the pressure regulator according to these stored values and drives the negative pressure control valve. J is characterized in that it is equipped with an arithmetic control circuit to reduce the negative pressure introduced into the pressure regulator when starting the engine with high fuel temperature, and to gradually release the reduced pressure of the introduced negative pressure after starting the engine. Fuel injection Q・1 type internal combustion engine +! ! l fuel pressure control device.