JPH08100744A - Fuel pressure regulator - Google Patents

Abstract

PURPOSE: To simplify the operation by enabling characteristics of fuel pressure to be mechanically switched with a simple structure. CONSTITUTION: An atmospheric pressure chamber 66 and an intake pipe pressure chamber 67 are formed on the side of a spring chamber 55 by being divided by means of a second diaphragm 65, a push rod 68 is attached to the second diaphragm 65, the end of a spring 62 is locked by inserting the push rod 68 into the spring chamber 55, and the spring load is mechanically increased according to differential pressure between both pressures when the intake pipe pressure is larger than the atmospheric pressure. When a fuel pressure regulator is applied to an engine provided with a supercharger, the fuel pressure level is governed in the non-supercharging range of low load and the supercharging range of high load while being switched to the high or low level.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel pressure regulator which is provided in a fuel injection device for a vehicle engine and which regulates the pressure of fuel that is pressure-fed to an injector, that is, the fuel pressure. And a mechanical fuel pressure regulator.

[0002]

2. Description of the Related Art A fuel supply system for a vehicle engine is
Generally, a fuel pressure regulator is provided in the middle of the fuel system to adjust the fuel pressure applied to the injector in relation to the suction pipe pressure that changes according to the operating state. Thus, the fuel injection amount when fuel is injected from the injector is controlled by the valve opening time of the injector.

In the conventional fuel pressure regulator, the fuel flows into one fuel chamber of the diaphragm, the suction pipe pressure is introduced into the other spring chamber, and the spring load provided in the spring chamber acts on the fuel chamber side. To do. Further, a valve is provided between the diaphragm and the fuel outlet pipe, and when the fuel pressure becomes high or the suction pipe pressure becomes low, the valve is opened and the fuel is returned to the fuel tank to reduce the fuel pressure. When the suction pipe pressure arbitrarily changes depending on the operating state, the fuel pressure is always set higher than the suction pipe pressure by the load of the spring, and the differential pressure between the fuel pressure and the suction pipe pressure is made constant.

Here, the supercharged engine is required to inject a large amount of fuel by the injector to obtain a high output in the supercharging region of high rotation and high load, but in the high revolution region, the valve of the injector is opened. There is a time limit, and it is necessary to inject a large amount of fuel in a short time. However, if the fuel pressure by the fuel pressure regulator is always controlled to a constant differential pressure as described above, in order to inject a large amount of fuel in a short time, there is no choice but to take a method of increasing the diameter of the nozzle of the injector. On the other hand, for example, in a low load non-supercharging region such as idling, fuel saving is required, and therefore it is necessary to finely control the fuel injection of the injector.In this case, if the nozzle diameter is large, fine control is possible. Can not.

Thus, in the engine with the supercharger,
The injector fuel injection requirements differ greatly between the high-load supercharging region and the low-load non-supercharging region. Therefore, as a method of satisfying both of these requirements, it is desired to switch the fuel pressure characteristic by the fuel pressure regulator between high and low depending on the supercharging region and the non-supercharging region.

Conventionally, a fuel pressure regulator capable of switching the fuel pressure characteristic between high and low is disclosed in, for example, Japanese Patent Laid-Open No. 2-136.
There is a prior art of Japanese Patent No. 561. In this prior art,
An electric actuator is attached to a spring receiver on the side opposite to the diaphragm in a spring chamber which is provided with a spring and in which the suction pipe pressure is introduced. In the high rotation or high load region, it is shown that the actuator is actuated by an electric signal to largely change the load of the spring, the fuel pressure is switched to a high characteristic, and the fuel injection amount is increased.

[0007]

By the way, in the above prior art, since the electric actuator is mounted on the spring receiver of the fuel pressure regulator,
The structure becomes complicated. Moreover, it is necessary to operate the actuator by an electric signal. In particular, when the fuel pressure characteristics are changed steplessly, a stepping motor is used as an actuator, which causes a problem that the structure and control become complicated.

In view of the above points, the present invention has an object of simplifying the structure and operation by making it possible to mechanically switch the characteristics of the fuel pressure.

[0009]

In order to achieve this object, a fuel pressure regulator according to claim 1 of the present invention comprises a first fuel pressure regulator.
A pressure chamber is provided with a spring in one of the diaphragms, into which the suction pipe pressure is introduced, and a fuel chamber into which the fuel flows into the other, and the fuel flows out through a valve provided in the first diaphragm. In the regulator,
The spring chamber is divided into an atmospheric pressure chamber and a suction pipe pressure chamber by a second diaphragm, and is attached. A push rod is attached to the second diaphragm, and the push rod is inserted into the spring chamber so that the end of the spring is attached. It is characterized in that it is locked and the spring load is increased according to the pressure difference between the two when the suction pipe pressure is higher than the atmospheric pressure.

[0010]

Therefore, according to claim 1 of the present invention, when applied to a supercharged engine, for example, in the low load non-supercharged region, the suction pipe pressure becomes a negative pressure, so that the spring It stretches most and its load becomes smaller. Therefore, the fuel pressure level becomes low, and when the injector opens the valve by the injection signal, the fuel is injected in a small amount, and the fuel injection amount is controlled to be fine and fuel saving. In addition, when the suction pipe pressure becomes higher than the atmospheric pressure in the medium and high load supercharging region, the push rod rushes into the spring chamber through the second diaphragm due to the pressure difference between the suction pipe pressure chamber and the atmospheric pressure chamber, and the spring is pushed. As it compresses, its load increases. Therefore, it is possible to mechanically switch to a high fuel pressure level characteristic, which allows a large amount of fuel to be injected in an increased amount of fuel pressure level in a short time to obtain a high output engine characteristic. Both high and high power requirements are met.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 4, the overall configuration of the supercharged engine will be described. Reference numeral 1 denotes, for example, an engine body of a horizontally opposed engine, in which cylinder heads 3 and rocker covers 4 having a valve operating mechanism are arranged on the left and right banks of a crankcase 2. As an intake system, an air cleaner 5 is communicated with a blower 7a of a turbocharger 7 via an intake duct 6,
The discharge side of the blower 7a is connected to the intake ports of the left and right cylinder heads 3 via an intake pipe 8, a throttle body 10 having a throttle valve 9, and an intake manifold 11.
Further, in the throttle body 10, a passage 13 having an idle adjusting screw 12 and a passage 15 having a first idle solenoid 14 when the air conditioner is used are communicated by bypassing the throttle valve 9, and the intake pipe 8 and the intake manifold 1 are connected.
During the period 1, the passage 17 having the Augiary valve 16 for cold start and warm-up operation is bypassed and communicated.

As an exhaust system, the exhaust manifolds 20 from the exhaust ports of the cylinder heads 3 of the left and right banks are gathered in one exhaust pipe 21, and this exhaust pipe 21 is connected to the turbine 7b of the turbocharger 7, the catalyst 22 and the like. Communicated. Then, the blower 7a is rotationally driven together with the turbine 7b by the energy of the exhaust gas to compress the air and supercharge the air.
Further, a wastegate valve 25 having an actuator 24 is provided in the bypass passage 23 of the turbine 7b, and the discharge side of the blower 7a communicates with the actuator 24 via the boost pressure passage 26, so that the boost pressure rises above a set value. The actuator 24 opens the waste gate valve 25 to control the boost pressure.

In the fuel system, an injector 30 for injecting fuel is installed in the intake port of each cylinder. Further, the fuel A in the fuel tank 31 is supplied to the injector 3 via the filter 34 by the fuel pump 33 provided in the delivery passage 32.
It is fed to the fuel pressure regulator 50 while being pumped to 0.
The fuel pressure regulator 50 mechanically switches the fuel pressure characteristics by using the suction pipe pressure. The fuel pressure regulator 50 adjusts the fuel pressure characteristics while changing the fuel pressure characteristics and returns the fuel A. The passage 35 is configured to circulate back to the fuel tank 31.

As an electronic control system, a crank angle sensor 40 for detecting the engine speed and the like, an air flow meter 41 for detecting the intake air amount, an O2 sensor 42 for detecting the state of the air-fuel ratio, and a throttle sensor 4 for detecting the throttle opening.
3 and the like, and these sensor signals are input to the control unit 44. The control unit 44 calculates the valve opening time at the time of fuel injection according to the operating state, the air-fuel ratio, etc., from the sensor signal, and outputs this injection signal to the injector 30.

Referring to FIG. 1, the fuel pressure regulator 50 will be described in detail. Here, since the suction pipe pressure changes together with the supercharging pressure depending on the engine operating state, the fuel pressure characteristic can be mechanically changed steplessly by changing the spring load using this suction pipe pressure. Therefore, the inside of the case 51 is divided into two by the partition plate 52, one of the partition plates 52 is partitioned into the fuel chamber 54 and the spring chamber 55 by the first diaphragm 53, and the other of the partition plate 52 is separated by the second diaphragm 65 into the atmosphere. It is divided into an atmospheric pressure chamber 66 opened to the inside and a suction pipe pressure chamber 67 for switching the fuel pressure characteristic.

In the fuel chamber 54, high-pressure fuel A flows in through a fuel inlet pipe 56 that communicates with the delivery passage 32 from the injector 30, and a fuel outlet pipe 57 that communicates with the return passage 35 extends near the diaphragm 53. It A ball-shaped valve 59 is attached to the attachment 58 at the center of the first diaphragm 53, and a valve seat 60 is provided at the tip of the fuel outlet pipe 57 so as to face the valve 59. The valve 59 opens and closes the valve seat 60 to return the fuel A. The intake pipe pressure Pi is introduced into the spring chamber 55 in communication with the passage 61 from the intake manifold 11, and the spring 6 is attached to the fixture 58 of the first diaphragm 53 in the spring chamber 55.
One end of 2 is locked.

The intake pipe pressure chamber 67 is also the intake manifold 11
The suction pipe pressure Pi is introduced in communication with the passage 61 from
The push rod 6 is provided at the center of the second diaphragm 65 that flexes according to the pressure difference between the suction pipe pressure chamber 67 and the atmospheric pressure chamber 66.
8 is attached. The push rod 68 is inserted into the spring chamber 55 through the hole 52a of the partition plate 52 with the stopper 68a restricting the backward movement, and the other end of the spring 62 is locked to the push rod 68. When the suction pipe pressure Pi becomes larger than the atmospheric pressure Po during supercharging,
By pushing the push rod 68 into the spring chamber 55 and compressing the spring 62 according to the pressure difference between the two, the load is increased by an increasing function with respect to the pressure difference as shown in FIG.

Next, the operation of this embodiment will be described. In a low load region such as idling operation, a small amount of air corresponding to the small opening of the passage 13 of the idle adjusting screw 12 and the throttle valve 9 is sucked in, and the fuel injection amount by the injector 30 is also small. For this reason, the energy of the exhaust gas is small and the turbocharger 7 does not operate, so that the intake pipe pressure Pi of the intake manifold 11 becomes a negative pressure in the state of natural intake.

At this time, in the fuel system, the fuel A in the fuel tank 31 is pressure-fed to the injector 30 by the fuel pump 33, flows into the fuel chamber 54 of the fuel pressure regulator 50, acts on the first diaphragm 53, and acts as the spring chamber 55. The suction pipe pressure Pi of the suction pipe pressure chamber 67 becomes a negative pressure. Therefore, the second diaphragm 65 is sucked by the pressure difference between the suction pipe pressure Pi and the atmospheric pressure Po, and the push rod 68 is at the lowest position where the stopper 68a is engaged with the partition plate 52, and the spring 62 is extended to the maximum. The load becomes the smallest F1 as shown in FIG.

Therefore, the suction pipe pressure Pi of the spring chamber 55
When the fuel pressure Pf of the fuel chamber 54 is higher than that of the spring 62 in which the load is smallest, the valve 59 is opened to return the fuel A, so that the fuel pressure is lowered, and conversely, when the fuel pressure Pf is low. The valve 59 is closed and the fuel pressure rises. As a result, the fuel pressure Pf is adjusted higher than the suction pipe pressure Pi by the spring load F1 as shown in FIG. 3, and in this case, the spring load F1 has the lowest fuel pressure level. Therefore, when the injector 30 is opened by the injection signal, it is possible to inject a small amount of fuel due to the lowest fuel pressure level, and the fuel injection amount is controlled to be fine and fuel saving.

In the middle and high load regions, the amount of air and fuel increases and the energy of exhaust gas increases, so that the turbocharger 7
Rotates at high speed to compress the air sucked from the air cleaner and supply the compressed air to the cylinder so that the suction pipe pressure Pi becomes a positive pressure.
At this time, if the suction pipe pressure Pi becomes higher than the atmospheric pressure Po,
In the fuel pressure regulator 50, the second diaphragm 65
Is pushed by the pressure difference between the two, and therefore the push rod 68 rushes into the spring chamber 55 and the spring load is
It increases to F2 in FIG. Therefore, the fuel pressure level becomes a high fuel pressure shown in FIG. 3, and the fuel is easily discharged from the injector 30.

In the high load region where the supercharging pressure is the highest, the load of the spring 62 is the largest F3 in FIG. 2, and the fuel level is the highest fuel pressure as shown in FIG. Therefore, even if the valve opening time of the injector 30 is the same as the non-supercharging region,
A large amount of fuel can be injected as the fuel pressure level increases. Therefore, even at high rotation speed, a large amount of fuel is injected in a short time to obtain high output engine characteristics.

[0023]

As described above, in the fuel pressure regulator according to the first aspect of the present invention, the atmospheric pressure chamber and the suction pipe pressure chamber are attached to the spring chamber side by being partitioned by the second diaphragm. , The push rod is attached to the second diaphragm, the push rod is inserted into the spring chamber to lock the end of the spring, and only when the suction pipe pressure is higher than the atmospheric pressure, the spring load is applied according to the pressure difference between the two. The fuel pressure can be adjusted by mechanically switching the fuel pressure characteristics in a stepless manner. Moreover, the structure is simple and cost effective, and electric control is not required by using the suction pipe pressure. Therefore, when applied to a supercharged engine, in a low-load non-supercharging region, the fuel pressure level can be suppressed to a low level, so fuel control can be performed with high accuracy to save fuel consumption, and high-load supercharging can be performed. In the region, since the fuel pressure level can be increased, a large amount of fuel can be injected in a short time, and high output can be obtained.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a fuel pressure regulator according to the present invention.

FIG. 2 is a diagram showing a load characteristic of a spring.

FIG. 3 is a diagram showing a fuel pressure regulation state.

FIG. 4 is an explanatory diagram showing an example of an engine with a supercharger.

[Explanation of symbols]

 50 Fuel Pressure Regulator 53 First Diaphragm 54 Fuel Chamber 55 Spring Chamber 59 Valve 62 Spring 65 Second Diaphragm 66 Atmospheric Pressure Chamber 67 Suction Pipe Pressure Chamber 68 Push Rod

Claims (1)

[Claims] 1. A spring chamber in which a spring is provided in one of the first diaphragms to introduce a suction pipe pressure, and a fuel flows into the other chamber, and the fuel flows out through a valve provided in the first diaphragm. In a fuel pressure regulator provided with a chamber, a spring chamber is divided into an atmospheric pressure chamber and a suction pipe pressure chamber by a second diagram, and a push rod is attached to the second diaphragm. A fuel pressure regulator which is inserted into a chamber to lock an end of a spring, and increases a spring load according to a pressure difference between the two when the suction pipe pressure is higher than the atmospheric pressure.