JPS60116851A - Fuel pressure controlling apparatus for fuel injection engine - Google Patents

Abstract

PURPOSE:To prevent generation of vapor in a fuel passage and to thereby prevent degradation of the engine starting performance, by raising the fuel pressure by raising the valve opening pressure of a pressure regulator, and thereby raising the boiling point of fuel at the time of hot restarting of an engine. CONSTITUTION:At the time of hot restarting of an engine after operation of the engine is stoped, a solenoid valve 17 is energized and closed by a control mechanism 30 and a by-pass passage 16 is closed. A valve 20b of a second pressure regulator 36 is opened when the fuel pressure becomes higher than a predetermined value, and fuel is returned via a return passage 22. On the other hand, a valve 20a of a first pressure regulator 35 is opened when the pressure is raised to the above fuel pressure plus the valve opening pressure of the regulator 35, that is, when the pressure is raised to a level two times as high as the pressure at the time of starting the engine. Since, by employing such an arrangement, the fuel pressure on the downstreams side of a fuel pump 3 is raised and the boiling point of fuel is raised resultantly, it is enabled to prevent the generation of fuel vapor.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a fuel pressure control device for a fuel injection engine equipped with an electronically controlled fuel injection device used in a vehicle or the like. In a fuel injection engine, the fuel temperature may rise due to heat within the engine route after the engine has stopped.

In particular, when the engine is stopped after driving the vehicle at high speed (high engine speed) and the radiator fan stops, the temperature inside the engine and engine room will rise rapidly, and the temperature of the fuel stagnant in the injection device such as the injector and the fuel pipe will increase. Exposure to this high temperature increases the temperature.

When the fuel temperature increases, the vaporization of the stagnant fuel causes a so-called vapor vent phenomenon.

For example, even in an engine where the fuel pressure is controlled at 2.55 kg/crri', vapor is generated when the fuel temperature reaches about 98° C. in the case of normal gasoline.

If the engine is restarted in this state, that is, in a state where the fuel temperature has not decreased, restarting the engine may be difficult or impossible due to the vapor lock phenomenon.

The present invention mainly relates to improving the startability of the engine during such a hot restart.

(Prior art) In a fuel injection engine equipped with an electronically controlled fuel injection device, the fuel pump installed in the fuel supply system from the fuel tank to the injector has a fuel injection rate of 4 to 5 kg/cm', although it varies depending on the engine. A pressure regulator of 5°Okg/am' is applied and the pressure of the fuel sent to the intake manifold is controlled by an endulator, and the pressure regulator is connected to the internal spring force and the intake manifold. pressure (usually negative pressure, but depending on the engine it may be positive pressure.

), when the supplied fuel pressure increases,
A portion of the fuel is returned to the fuel tank, thereby maintaining the pressure of the supplied fuel at a predetermined value. Note that this is done with the intake manifold rather than the injector.

Control of this injection time is performed by a control unit, to which an electrical signal from an 8M sensor is input. This change is due to changes in the pressure of the injected fuel due to changes in the intake manifold pressure (mainly negative pressure acts, but in engines equipped with a turbocharger, positive pressure acts during supercharging during turbo operation). Even if there is, it is necessary to control the injection time to make the fuel injection amount appropriate, but this pressure change is also input to the control unit.As mentioned above, a normal pressure regulator controls the manifold negative pressure. Because it is used as an element, when the manifold negative pressure suddenly rises at the same time as the engine starts (by cranking during engine start), the pressure regulator operates and returns fuel to the fuel tank, resulting in the fuel being reduced. The pressure drops rapidly (this also varies depending on the engine, but for example from about 2.55 kg/cm' to about 2.0 kg/cm')
kg/cm''), and its boiling point also decreases. Therefore, when restarting the engine or the engine room at a high temperature, such as after driving at high speed, the boiling point of the fuel decreases due to the decrease in fuel pressure. This causes a problem in that vapor is generated in the fuel passage, causing vapor lock and reducing startability.For this reason, in order to prevent the manifold negative pressure from acting on the pre-lash regulator at the time of starting, the negative pressure is transferred to the pressure regulator. There are some methods that prevent the fuel pressure from dropping by closing the pipes that lead to the engine, thereby suppressing the generation of vapor.However, even in this case, it is not possible to increase the pressure at startup, so vapor is generated due to the drop in fuel pressure. Even if the vapor is suppressed, it does not contribute much to eliminating the vapor that occurs between engine stop and restart and remains in the injector or fuel pipe, especially when the fuel temperature is very high. It was insufficient to continue ignition after the first explosion, as shown below.

In other words, in a fuel injection engine equipped with an electronically controlled fuel injection device, a single explosion due to cranking during startup (
The first explosion takes place well, but the fuel becomes thin due to a leak in the injector or fuel pipe, and the next explosion does not continue after the first explosion.In order to eliminate the situation where the engine does not start, There was a shortage.

It is also possible to lengthen the opening time of the injector valve to prevent vapor generation and reduce the amount of fuel, but this will prevent the fuel from flowing more than necessary when the vane is not generating forcefully. There is a strong possibility that the ignition will become too dense and difficult to ignite. A fuel injection engine that increases the fuel pressure and prevents the generation of vapor, and also eliminates the vapor generated before ltJ starts, thereby preventing a decrease in engine startability at a hot 1-no-start. To provide fuel pressure control device.

(Structure of the invention) A fuel chamber and a pressure adjustment chamber are provided between a fuel supply system connected to a fuel tank and provided with a fuel pump, injector, etc. on the way, and a fuel return system connected to the fuel tank and returning fuel. A first pressure regulator, a second pressure regulator having a fuel chamber and a pressurizing chamber are provided, and a connecting pipe connects the fuel chamber of the first pressure regulator and the fuel chamber of the second pressure regulator. is provided, the fuel chamber of the first pressure regulator has a pipe end of the fuel supply system opened, and the pressure adjustment chamber has a spring and has an open end of a pressure transmission pipe connected to the intake manifold. A diaphragm is provided between the pressure adjustment chamber and the fuel chamber, and a valve is provided on the diaphragm. 1
A pressure regulating section is formed, a pipe end of a fuel return system is opened in the fuel chamber of the second pressure regulator, a diaphragm is provided between the fuel chamber and the pressurizing chamber, and a diaphragm is provided between the fuel chamber and the pressurizing chamber. A second pressure adjustment part is formed between the valve and the pipe end of the fuel return system to adjust the amount of fuel returned to the fuel tank,
A spring acting in the direction of closing the pipe end of the fuel return system by the valve force t011 is provided in the pressurizing chamber, and the spring is connected to the middle of the pipe of the fuel return system and the fuel chamber of the second pre-pressure regulator. Concatenate. A bypass path was provided, and a switching valve was provided in the middle of the bypass path to shut off the bypass path when the engine was restarted.

(Effects of the Invention) Therefore, in the fuel pressure control device of the present invention,
When the engine is restarted, the switching valve is activated,
By closing the bypass path, the return ♀ of fuel to the fuel tank is throttled into two stages by two pressure regulators, the first pressure regulator and the second pressure regulator, thereby reducing the pressure in the second pressure regulator. act on the first pressure regulator to increase the valve opening pressure of the first pressure regulator;
The fuel pressure is increased to raise the boiling point of the fuel, thereby suppressing the generation of vapor in the fuel passage, as well as eliminating the vapor generated and staying in the injector and fuel pipe, thereby reducing vapor. Effectiveness (given) to prevent the occurrence of oil leakage and to prevent deterioration of engine startability.

(Embodiment) A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows the configuration #2m of the fuel pressure control device according to the present invention.
FIG. 2 is a longitudinal sectional side view of the i-pressure regulator and the hysteroid valve.

In FIG. 1, reference numeral 1 denotes a fuel tank, and a pipe 2 leads out from the fuel tank 1, and is connected to the suction side of a fuel pump 3 that supplies fuel to this fuel tank 2L. and,
The discharge side of the fuel pump 3 is connected to 5 parts in the evening to smooth out the movement of the fuel wheel '1 delivered by the fuel pump via the fuel pump 4 and adjust the flow to be uniform. 1131.
, In the middle of this vibro is a fuel fill 7 as shown in the figure.
is interposed.

The above-mentioned vibro is a pipe 8 constituting a circuit whose end is connected to a first pressure regulator 35 to be described later.
As shown in the figure, two types of pipes 9 and 10 are branched from the pipe 8, and the end of one pipe 9 is connected to an injector 13 that injects fuel near the intake valve 12 of the intake manifold 11. connected to the pipe 9
are provided corresponding to the number of cylinders in the engine.

The other end of the pipe IO is connected to a cold start valve 14 that injects fuel into the intake manifold 11 to improve engine startability in cold weather.

In this way, pipes 2, 4, 6° 8.9, 10. Fuel pump 3. Damper 5. It consists of a fuel filter 7, an injector 13, etc., and forms a conduit of a fuel supply system that supplies fuel to the injector 13. Further, as shown in the figure, a first pressure regulator 35 and a second pressure regulator 36 are connected in series to the pipe 8, and the second pressure regulator 36 regulates the pressure of the fuel injected from the injector 13. A return pipe 22 that is connected to the fuel tank l and forms a conduit for a fuel return system that returns fuel.
A bypass passage 16 is provided with one end connected to the return pipe 22 and the other end connected to the second pressure regulator 36, and a solenoid valve 17 is interposed in the middle of the bypass passage 16. consists of a bypass passage 16a that connects the solenoid valve 17 and the second pressure regulator 36, and a bypass passage 16b that connects the return pipe 22 and the solenoid valve 17.

Inside the pressure regulators 35 and 36 is a diaphragm 18a, as shown in detail in FIG.

18b is divided into a first fuel chamber Sla, a second fuel chamber Slb, a pressure adjustment chamber S2a, and a pressurizing chamber S2b.
One end of valve 9 is opened, and the other end of connecting pipe 19 and the end of return pipe 22 are opened in second fuel chamber Slb, and valves 20a are attached to diaphragms 18a and 18b, respectively.

20b opens and closes the end openings of these pipes 19,20. On the other hand, the diaphragms 18a and 18b are installed in the pressure adjustment chamber S2a and the pressurization chamber SZb.
a, 20b17) Springs 2La and 21b are each compressed and biased in the closing direction (upward in the figure).

Further, the pressure adjustment chamber 32a and the pressurization chamber S2b are each communicated with the intake manifold via the pressure transmission pipe 23, so the pressure in these pressure adjustment chamber S2a and the pressurization chamber SZb corresponds to the intake manifold pressure. changed,
First pressure adjustment section 35a and second pressure adjustment section 36a, respectively.
is formed. Note that only a spring may be provided in the pressurizing chamber S2b so as not to transmit the pressure (mainly negative pressure) of the intake manifold.

On the other hand, the no. 1111 valve/help 17 has a valve body 24 slidably held therein as shown in FIG. 2, and a solenoid 25 is housed around the valve body 24. and,
The valve body 24 is connected to the bypass passage 16a by the spring 26.
A bullet is being fired in the direction that connects 16b.

1- The drive of the solenoid 25 is controlled by a control mechanism 30 shown in FIG. 1, and the control mechanism 30 is connected to the ignition switch 31. It consists of a timer 32° and a water temperature switch 33, and when the water temperature is high, the solenoid 2 of the solenoid valve 17 is activated for a certain period of time after the ignition switch is turned on.
5 to close the bypass passage 16.

*Ta. The 34ti control unit controls the opening/closing time of the valve of the injector 13 and the injection amount based on signals input from various sensors, and is the same as the conventional one as described above.

Incidentally, instead of the water temperature switch 33, a fuel temperature switch or an engine cylinder block temperature switch may be used, or instead of the ignition switch 31, a switch that is turned on by a signal when the starter is turned on. While the engine is operating other than during a hot restart, the control mechanism 30 does not drive the solenoid valve 17;
Therefore, the bypass paths 16a and 16b are in communication with each other,
When the diaphragm 18b is driven by negative pressure acting on the pressurizing chamber S2b, most of the fuel entering the fuel chamber S1b of the 26th pressure regulator 36 is If the diaphragm 18b is not activated, the entire amount is returned to the fuel tank 1 through the bypass paths 16a, 16b. For this reason, fuel is first pressure-fed from the fuel tank 1 to the fuel pump 3 and the damper 5, whose pulsation is suppressed by the damper 5, and after being economized by the fuel filter 7, it is fed to the injector 13 and the cold start valve 14. be done. Then, in the injector 13, fuel is injected into the vicinity of the intake valve 12 of the injector 11 at a pressure determined by a first pressure regulator 35 that is controlled by the pressure (mainly negative pressure) in the intake manifold. The remaining fuel that has not been injected by the injector 13 passes through the pipe 8 to the first pre-injector.
is introduced into the fuel chamber Sla of the engine pressure regulator 35,
The acid is throttled at valve 20a. Next, this fuel passes through the connecting pipe 19 to the second pressure regulator 36
However, since the solenoid valve 17 is in the open state as shown in FIG. 2 at this time, most of it flows into the return pipe 22 through the small resistance side bypass passage 16. , and is returned to the fuel tank l through the return pipe 22. Therefore, while the engine is operating, only the first pressure regulator 35 functions, and thereby the fuel pressure in the pipe 8, that is, the fuel pressure supplied to the injector 13, is maintained at a predetermined value, for example, 2.55 kg/c. .

On the other hand, during a hot restart, the control mechanism 30 excites the solenoid 25 of the solenoid valve 17, and the solenoid 25 moves the valve body 24 upward in FIG. 2 against the spring 26, resulting in bypass paths 16a and 16b. communication is cut off. Therefore, the return fuel is throttled in two stages by both pressure regulators, and the fuel pressure increases.

That is, since the bypass passage 16 is closed, the valve 2ob of the second pressure regulator 36 is opened to return the fuel. At this time, the valve 20b of the pressure regulator 36 of NS2 is controlled by the spring 21b and the negative pressure, and will not open unless the fuel pressure reaches a predetermined value. Since the above pressure acts on the first pressure regulator 35, the fuel pressure is higher than the pressure controlled by the pull 21a of the first pressure regulator 35 and the negative pressure plus the above pressure. If no pressure acts on valve 21a, valve 21a will open and no fuel will be returned.

For example, negative pressure during cranking usually causes 2,
55 kg7cm' of fuel 1 [but 2, 0 kg/cm
Even if the valve 20b of the second pressure regulator 36 opens at a fuel pressure of 2.0 kg/Cm', the first pressure regulator 35
The valve 20a has a valve opening pressure of 2.0 kg/ctl' of the second pressure regulator 36 and a valve opening pressure of 2.0 kg/cm' of the first pressure regulator 35.
Since the valve will not open unless the fuel pressure is 4.0 kg/cm' or higher, the fuel pressure will be 4.0 kg/cm.
It is keyed to m'. Then, the burner fH2 is on top! I
I, the boiling point of the fuel will inevitably be above 91 L, for example,
Fuel pressure from 2.55 kg/cm' to 3.0 kg
/cm', the fuel temperature will go from lOO℃ to 110℃
However, it has been confirmed that vapor generation is eliminated, and 4
When the temperature reaches 0 kg/cm', the effect occurs even at higher temperatures, and the vapor that was generated and stagnant in the injector and fuel pipe disappears, and the fuel pressure does not drop even during cranking at startup, so the fuel The generation of vapor due to pressure drop is suppressed, preventing the occurrence of vapor lock, and furthermore,
Since the accumulated vapor is eliminated, the fuel does not become thin and the ignition following the initial explosion is performed normally. As a result, deterioration of engine start control is effectively prevented.

Since the fuel pressure will be higher than normal, the injector valve opening time will be adjusted to shorten the injected fuel so that the injected fuel will not be concentrated.Input that the solenoid valve 17 is activated is input to the control unit 34, and the control unit 34 as before. 34 controls the injection time of injector 3.

The control mechanism 30 opens the valve body 24 of the solenoid valve 17 after a certain period of time has elapsed from the timer 32 turning on the engine pressure. controlled by

Increasing the fuel pressure during a hot restart only for a certain period of time in this way is to ensure that the fuel that remains in the injector or fuel line and has risen in temperature is consumed, or that the fuel in the fuel tank returns to normal. Since the temperature is not high, no vapor is generated, so all you have to do is increase the fuel pressure for a period of time (approximately 30 seconds, depending on the car) until the fuel in the tank is injected.

Furthermore, the solenoid valve 17 may be another switching valve, and the control of the solenoid valve 17 is such that at the time of ho/restart, the solenoid 25 of the solenoid valve 17 is not energized and the bypass path 16 is closed, and under normal conditions, the solenoid 25 is energized and bypassed. valve body 24 to open passage 16. spring 2
6 etc. may be configured.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a fuel pressure control device according to the present invention, and FIG.
The figure is a vertical side view of a pressure regulator and a solenoid valve. 1-...fuel tank, 3...Φ fuel pump, 5-IIψ
Damper, 71I...Fuel filter, 11...-Intake valve, 13.Φ.Injector, 35...-First pressure regulator, 3e---Tfi2 pressure regulator, 17...-Solenoid valve,
30...Control mechanism. Patent applicant: Nissan Shatai Co., Ltd. Sub-agent Patent attorney: Hiroshi Fujiwara

Claims (1)

[Claims] A first pressure regulator that has a fuel chamber and a pressure adjustment chamber between a fuel supply system that is connected to the fuel tank and is provided with a fuel pump, injector, etc. on the way, and a fuel return system that is connected to the fuel tank and returns fuel. a second pressure regulator having a fuel chamber and a pressurizing chamber;
A connecting pipe is provided to connect the fuel chamber of the first pressure regulator and the fuel chamber of the second pressure regulator, and the pipe end of the fuel supply system is opened in the fuel chamber of the first pressure regulator. The pressure adjustment chamber has a spring, the end of the pressure transmission pipe connected to the intake manifold is open, a tire flammable is provided between the pressure adjustment chamber and the fuel chamber, and a valve is provided in the diaphragm. A first pressure regulating part is formed between the valve and the end of the connecting pipe to adjust the return line to the fuel tank by the pressure of the intake manifold, and a fuel return system is provided in the fuel chamber of the second pressure regulator. The pipe end of the fuel return system is opened, a tire flam is provided between the fuel chamber and the pressurizing chamber, and the return pipe to the fuel tank is connected between the valve and the pipe end of the fuel return system. A second pressure adjustment section is formed to adjust the pressure, and the pressurizing chamber is provided with a spring that acts in a direction in which the valve closes the pipe end of the fuel return system. A bypass passage is provided which connects the fuel chamber of the second pressure regulator, and a switching valve is provided in the middle of the bypass passage to shut off the /haypass passage on the hot lister 1 surface of the engine. Fuel pressure control device for fuel injection engines.