JPH1137017A - Fuel supply equipment for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To hold the pressure of fuel supplied to injectors in fuel supply equipment for an internal combustion engine while an internal combustion engine is stopped to a proper pressure. SOLUTION: Fuel supply equipment for an internal combustion engine stops with its control circuit 45 an internal combustion engine when an ignition switch 33 turned on is switched off and also energization to an electromagnetic coil 42 in a vacuum control valve 41 at a shorter time lag from the switching-off of the switch 33 to thus close a valve element 44 in the control valve 41, which operation confines negative pressure led from an intake line 11 in a pressure supply pipe 39. In that state, excessive pressurization of fuel in a fuel supply pipe 15 opens a diaphragm valve 19 in a regulator 17 to thereby regulate the fuel pressure properly to or below a predetermined pressure, which operation prevents fuel leaks from injectors 12 to an intake manifold 11a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel supply system for an internal combustion engine, and more particularly to a fuel supply system for an internal combustion engine configured to maintain an appropriate fuel pressure supplied to an injector when the internal combustion engine is stopped. About.

[0002]

2. Description of the Related Art As a conventional fuel supply device for an internal combustion engine, for example, a conventional example 1 shown in FIG.
There is. In the conventional example 1 shown in FIG.
Reference numeral 1 denotes a downstream side communicating with the intake manifold 11a. The intake manifold 11a is provided with a plurality of injectors 12 for injecting fuel. Also,
An air filter 13 and a throttle valve 14 are provided upstream of the air supply passage 11. When the internal combustion engine is started up, the pressure in the air supply passage 11 changes from the atmospheric pressure to the negative pressure when the internal combustion engine is started.

A fuel supply line 15 is connected in parallel to each of the injectors 12. Fuel supply line 15
The upstream end is connected to a fuel pump 16, and the downstream end is connected to a fuel pressure regulator (hereinafter referred to as “regulator”) 17. still,
On the discharge side of the fuel pump 16, a fuel supply line 15 is provided.
A check valve 18 for preventing a backflow of the fuel discharged to is provided.

The regulator 17 has a diaphragm valve 19 provided therein. The diaphragm valve 19 divides the internal space of the regulator 17 into a diaphragm chamber 20 and a fuel pressure relief chamber 21. Diaphragm room 20
Is connected to a pressure introduction pipe 22 branched from the air supply path 11. Further, the fuel pressure relief chamber 21 is provided in the return line 2
The fuel tank 24 is in communication with the fuel tank 24 via the fuel tank 3.

[0005] The diaphragm valve 19 is urged by a spring 25 in a direction to close the end opening 15 a of the fuel supply pipe 15. When the internal combustion engine is started, a negative pressure of the air supply line 11 is introduced into the diaphragm chamber 20 via the pressure introducing line 22. Therefore, the diaphragm valve 19 is separated from the end opening 15 a of the fuel supply pipe 15 against the spring force of the spring 25.

[0006] The fuel pump 16 includes a fuel tank 24.
The internal fuel is pressurized and discharged to the fuel supply pipe 15 and supplied to each injector 12 via the fuel supply pipe 15. Then, a part of the fuel discharged from the fuel pump 16 is injected into the cylinder from the injector 12, and excess fuel not injected from the injector 12 reaches the fuel pressure relief chamber 21 of the regulator 17, and flows through the return line 23. Through the fuel tank 24. Therefore, when the internal combustion engine is running, the fuel in the fuel tank 24 pumped by the fuel pump 16 circulates through the fuel supply line 15, the fuel pressure relief chamber 21, the return line 23, and the fuel tank 24.

When the internal combustion engine is stopped, the pressure in the air supply line 11 changes from negative pressure to atmospheric pressure. When the atmospheric pressure of the air supply line 11 is introduced into the diaphragm chamber 20 via the pressure introducing line 22, the diaphragm valve 1
9 and the pressure of the diaphragm chamber 20 acting on the spring 2
The resultant force with the spring force of No. 5 is larger than the fuel pressure supplied to the fuel supply pipe 15. As a result, the diaphragm valve 19
Operates at a position to close the end opening 15a of the fuel supply pipe 15. Further, the check valve 18 provided at the upstream end of the fuel supply pipe 15 closes when the fuel pump 16 stops.

As a result, the downstream end of the fuel supply line 15 is closed by the diaphragm valve 19, and the upstream end is closed by the check valve 18. Therefore, the pressurized fuel is sealed in the fuel supply pipe 15. Therefore, when the internal combustion engine is restarted, the pressurized fuel held in the fuel supply pipe 15 is supplied to the injector 12, so that the startability is ensured.

FIG. 9 shows a second conventional example different from the first conventional example. In FIG. 9, the same parts as those in the conventional example 1 shown in FIG. In the second conventional example, an end of a pressure introduction pipe line 31 branched from an air supply line 11 is connected to a negative pressure control valve (VSV) 32. The negative pressure control valve 32 has an electromagnetic three-way valve structure, and has an electromagnetic coil 34 that is energized when an ignition switch (hereinafter, referred to as an “IG switch”) 33 is turned on. In addition, the negative pressure control valve 32
It has a valve body 36 urged by a spring 35.

When the electromagnetic coil 34 is energized, the valve body 36 is attracted by the electromagnetic force of the electromagnetic coil 34 to close the air introduction passage 37 formed in the electromagnetic coil 34 and to pressurize the pressure introduction line 31. Is opened. The end of the air introduction pipe 37 is connected to the air filter 3.
8 is communicated. When the IG switch 33 is turned off, the valve body 36 is displaced by the spring force of the spring 35 to open the air introduction pipe 37 and close the end opening 31a of the pressure introduction pipe 31. Further, a pressure supply pipe 39 for supplying a negative pressure or an atmospheric pressure is connected to a side surface of the negative pressure control valve 32. The downstream end of the pressure supply pipe 39 communicates with the diaphragm chamber 20 of the regulator 17.

Therefore, when the internal combustion engine is started, the IG switch 33 is turned on, so that the valve body 36 is attracted by the electromagnetic force of the electromagnetic coil 34. Since the end opening 31 a of the pressure introduction pipe 31 is open, the negative pressure of the air supply system path 11 is supplied to the pressure supply pipe 39. As a result, a negative pressure is introduced into the diaphragm chamber 20 of the regulator 17, and the diaphragm valve 19 of the regulator 17 separates from the end opening 15 a of the fuel supply pipe 15 against the spring force of the spring 25.

Accordingly, when the internal combustion engine is running, the fuel in the fuel tank 24 pumped by the fuel pump 16 circulates through the fuel supply line 15, the fuel pressure relief chamber 21, the return line 23, and the fuel tank 24. . And
When the IG switch 33 is turned off to stop the internal combustion engine, the valve element 36 of the negative pressure control valve 32
The air introduction pipe 37 is opened by being displaced by the spring force of 5, and the end opening 31a of the pressure introduction pipe 31 is closed.
As a result, atmospheric pressure is introduced into the diaphragm chamber 20 of the regulator 17. As a result, the diaphragm valve 19 of the regulator 17 is connected to the end opening 15 of the fuel supply pipe 15.
It operates at the position where it closes a.

Further, since the internal combustion engine is stopped and the fuel pump 16 is stopped, the fuel supply line 15 is stopped.
The check valve 18 provided at the upstream end is closed. Thus, the downstream end of the fuel supply pipe 15 is closed by the diaphragm valve 19, and the upstream end is closed by the check valve 18. Therefore, the pressurized fuel is sealed in the fuel supply pipe 15.

Therefore, when restarting the internal combustion engine,
Since the pressurized fuel held in the fuel supply line 15 is supplied to the injector 12, startability is ensured.

[0015]

In the first prior art, the diaphragm valve 19 of the regulator 17 is opened by the negative pressure generated in the supply line 11 of the internal combustion engine, and the atmospheric pressure is reduced by stopping the internal combustion engine. When it is introduced into the diaphragm chamber 20 via the introduction pipe 22, the diaphragm valve 19 closes the end opening 15 a of the fuel supply pipe 15. Further, when the internal combustion engine stops, the check valve 18 of the fuel supply line 15 is closed together with the stop of the fuel pump 16, so that
The pressurized fuel is sealed in the fuel supply line 15.

If this state is continued, the fuel sealed in the fuel supply pipe 15 may leak from the injector 12 to the intake manifold 11a little by little.
In this way, after stopping the internal combustion engine, the injector 1
If the fuel leaks from the fuel cell 2, when the internal combustion engine is started, there is a possibility that the amount of fuel supplied to the air supplied from the air supply passage 11 is too large and the ignition becomes difficult.

Further, in the above conventional example 2, the IG switch 3
When the engine 3 is turned off and the internal combustion engine is stopped, the valve element 36 of the negative pressure control valve 32 is displaced by the spring force of the spring 35 to open the atmosphere introduction pipe 37 and to close the end of the pressure introduction pipe 31. The opening 31a is closed. Therefore, the atmospheric pressure is introduced into the diaphragm chamber 20 of the regulator 17 simultaneously with the stop of the internal combustion engine, and the diaphragm valve 19 immediately closes the end opening 15 a of the fuel supply pipe 15.

Therefore, the fuel supply pipe 15 is maintained in a state in which the fuel pressurized by the fuel pump 16 is filled. As described above, since the fuel pressure supplied to the fuel supply line 15 supplied to the injector 12 is maintained even after the start, air bubbles may be generated in the fuel supply line 15 under a high temperature environment, for example. is there. Thus, when bubbles are generated in the fuel, the fuel mist injected from the injector 12 becomes lean, and the air-fuel ratio changes to a lean state. Therefore, the air-fuel ratio control becomes unstable.

For this reason, in the internal combustion engine, a control method is desired in which air bubbles generated in the fuel supply line 15 are injected into the intake manifold 11a at the time of starting as much as possible to stabilize the air-fuel ratio control after starting. Then, in order to inject the bubbles in as short a time as possible, the fuel pressure when the internal combustion engine is stopped is set high. Further, the negative pressure control valve 32 is controlled so as not to operate until a predetermined time elapses after the internal combustion engine is started.

However, when the state in which the fuel pressure in the fuel supply line 15 is increased while the engine is stopped is continued, the fuel sealed in the fuel supply line 15 is discharged from the injector 12 in the same manner as in the above-described conventional example 1. Leakage may occur little by little into the intake manifold 11a, and there is a possibility that the amount of fuel supplied to the air supplied from the air supply passage 11 becomes too large, so that ignition becomes difficult at the time of startup.

The present invention has been made in view of the above points, and has been made in consideration of the above-described problems. The fuel supply of an internal combustion engine for preventing fuel from leaking from an injector by setting the fuel pressure of a fuel supply pipe to a predetermined pressure or less after the engine stops It is intended to provide a device.

[0022]

To solve the above-mentioned problems, the present invention has the following features. According to the first aspect of the present invention, there is provided an injector for injecting fuel into an air supply passage, a pump for supplying fuel to the injector, and a fuel supply pipe for supplying fuel pressurized by the pump to the injector. A return line for returning excess fuel not injected from the injector to the fuel tank; a pressure introduction line for introducing a negative pressure of the air supply line; and a negative line through the pressure introduction line. A valve device for opening the valve so that the pressure of the fuel supply line becomes a predetermined pressure when the pressure is introduced and allowing the fuel to flow out to the return line. A shut-off means for closing the pressure introducing line so as to temporarily hold the negative pressure introduced into the pressure introducing line when stopped is provided.

According to a second aspect of the present invention, there is provided an injector for injecting fuel into an air supply passage, a pump for supplying fuel to the injector, and a fuel which is pressurized by the pump is supplied to the injector. A fuel supply line, a return line for returning excess fuel not injected from the injector to the fuel tank, a pressure introduction line through which the negative pressure of the air supply system is introduced, and a pressure introduction line. And a valve device for opening the valve so that the pressure of the fuel supply line becomes a predetermined pressure when a negative pressure is introduced via the fuel supply line to allow the fuel to flow out to the return line. A vacuum tank for accumulating a negative pressure of the fuel supply line, and supplying a negative pressure of the air supply line to a pressure chamber of the valve device when it is detected that the internal combustion engine is in an activated state, The engine is stopped A switching valve for supplying a negative pressure accumulated in the vacuum tank to the pressure chamber of the valve device so that the fuel pressure in the fuel supply line is adjusted to a predetermined pressure when the pressure is detected. It is characterized by the following.

Therefore, the present invention has the following effects. According to the first aspect of the present invention, when the internal combustion engine is stopped, the pressure introduction line is closed so that the negative pressure introduced into the pressure introduction line is temporarily held. When the fuel pressure in the fuel supply line becomes equal to or higher than a predetermined value, the pressure control valve can cause the fuel in the fuel supply line to flow out to the return line. As a result, it is possible to adjust the fuel pressure after the engine is stopped to an appropriate predetermined pressure or less, and it is possible to prevent fuel from leaking from the injector.

According to the second aspect of the present invention, when it is detected that the internal combustion engine is in the starting state, the negative pressure of the fuel supply line is supplied to the pressure chamber of the pressure control valve, and the internal combustion engine is stopped. When the state is detected, the negative pressure accumulated in the vacuum tank is supplied to the pressure chamber of the valve device so that the fuel pressure of the fuel supply line is adjusted to a predetermined pressure. When the fuel pressure in the passage exceeds a predetermined value, the pressure control valve can cause the fuel in the fuel supply line to flow out to the return line. As a result, it is possible to adjust the fuel pressure after the engine is stopped to an appropriate predetermined pressure or less, and it is possible to prevent fuel from leaking from the injector.

[0026]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram showing a schematic configuration of a fuel supply device for an internal combustion engine according to one embodiment of the present invention.
In FIG. 1, the same portions as those in FIGS. 8 and 9 are denoted by the same reference numerals, and the description thereof will be omitted.

In the fuel supply device for an internal combustion engine shown in FIG.
A negative pressure control valve (VSV) 41 is provided between the pressure introduction pipe 31 and the pressure supply pipe 39. This negative pressure control valve 4
Reference numeral 1 denotes an electromagnetic on-off valve, which has an electromagnetic coil 42 that is energized when the IG switch 33 is turned on. Further, the negative pressure control valve 41 has a valve body 44 urged by a spring 43. When the IG switch 33 is turned on or off, an on signal or an off signal of the IG switch 33 is input to a control circuit (ECU) 45.

When the OFF signal of the IG switch 33 is input to the ROM of the control circuit 45, a control program for delaying a predetermined time and stopping the energization of the electromagnetic coil 42, and turning on the IG switch 33 When a signal is input, a short pulse is output to the electromagnetic coil 42, and then the pulse is delayed for a predetermined time.
And a control program for starting energization of the power supply.

When the electromagnetic coil 42 is energized, the valve body 44 of the negative pressure control valve 41 is sucked in the valve opening direction by the electromagnetic force of the electromagnetic coil 42, and the end opening 31 of the pressure introduction pipe line 31 is opened.
The pressure communication pipe 31 and the pressure supply pipe 39 communicate with each other at a distance from a. As a result, the negative pressure of the air supply line 11 is introduced into the diaphragm chamber 20 of the regulator 17 via the pressure introducing line 31, the negative pressure control valve 41, and the pressure supply line 39.

Therefore, the diaphragm valve 19 of the regulator 17 separates from the end opening 15a of the fuel supply line 15 against the spring force of the spring 25 due to the fuel pressure of the fuel supply line 15, and moves away from the fuel supply line 15. And return line 2
3 is in a communication state. Therefore, when the internal combustion engine is running, the fuel stored in the fuel tank 24 pumped by the fuel pump 16 circulates through the fuel supply line 15, the fuel pressure relief chamber 21, the return line 23, and the fuel tank 24. .

When the IG switch 33 is turned off, the power supply to the electromagnetic coil 42 is stopped with a predetermined time delay. Therefore, the valve body 44 of the negative pressure control valve 41 demagnetizes the electromagnetic coil 42 and is displaced in the valve closing direction by the spring force of the spring 43 to close the end opening 31 a of the pressure introducing pipe 31. As a result, the pressure in the diaphragm chamber 20 of the regulator 17 and the pressure in the pressure supply pipe 39 are maintained in a state where a negative pressure is introduced.

FIG. 2 is a time chart for explaining the operation of the fuel supply system for an internal combustion engine shown in FIG. 2, when the IG switch 33 is operated from ON to OFF at time T _1, the control circuit 45 stops the engine. Along with this, the pressure in the air supply passage 11 gradually changes from negative pressure to atmospheric pressure. Since the fuel pump 16 has also stopped when the engine rotation has stopped, the check valve 18 closes the upstream end of the fuel supply pipe 15.

Then, the control circuit 45 controls the IG switch 3
The power supply to the electromagnetic coil 42 of the negative pressure control valve 41 is stopped with _a delay of a minute time ta after the switch 3 is turned off. Accordingly, the valve body 44 of the negative pressure control valve 41 performs a valve closing operation by the spring force of the spring 25. Therefore, the pressure supply line 39
Is in a state where the negative pressure introduced from the air supply passage 11 is contained. Therefore, the diaphragm chamber 20 of the regulator 17 connected to the pressure supply pipe 39 is maintained in a state where a negative pressure smaller than the negative pressure at the time of starting the engine is introduced.
In a state where the valve body 44 of the negative pressure control valve 41 is kept at the valve closing position, a slight air leak occurs from the valve body 44, so that the pressure in the diaphragm chamber 20 gradually increases.

The air leaking from the valve body 44 of the negative pressure control valve 41 gradually increases from the time T ₁ when the IG switch 33 is turned off to the time when the IG switch 33 is turned on, and the pressure supply pipe gradually increases. Route 39. Therefore, the pressure in the diaphragm chamber 20 of the regulator 17 slowly changes from the negative pressure to a pressure close to the atmospheric pressure. As described above, when the engine is stopped, the pressure in the diaphragm chamber 20 of the regulator 17 is maintained at a negative pressure. Therefore, when the fuel in the fuel supply line 15 is excessively pressurized, the diaphragm valve 19 of the regulator 17 is activated. The valve opens. for that reason,
The fuel pressure in the fuel supply pipe 15 is adjusted to a pressure equal to or lower than an appropriate predetermined pressure according to the negative pressure of the diaphragm chamber 20 and the spring force of the spring 25.

As a result, while the engine is stopped, the injector 1
2 can be prevented from leaking to the intake manifold 11a. As a result, when starting the internal combustion engine,
It is possible to prevent too much fuel for the air supplied from the air supply passage 11. Also, at time T _2, when the IG switch 33 is operated to ON, the control circuit 45 (in this embodiment, 0.5 seconds) minute time t _b energization to the electromagnetic coil 42 only the negative pressure control valve 41 I do. When the electromagnetic coil 42 is momentarily excited as described above, the pressure supply pipe 39 is maintained at the atmospheric pressure by the air introduced from the air supply path 11. As a result, the atmospheric pressure is confined in the pressure supply pipe 39. Therefore, the pressure in the diaphragm chamber 20 to which the pressure supply pipe 39 communicates changes to the atmospheric pressure.

As a result, the downstream end of the fuel supply line 15 is closed by the diaphragm valve 19 of the regulator 17. At the same time, the fuel pump 16 is started, so that the fuel pressure in the fuel supply line 15 increases. The pressure (surge tank pressure) air supply pathway 11, starts to change from atmospheric pressure to a negative pressure after the short time t _b. Therefore, the injector 12 moves from the intake manifold 11
Mist fuel is injected from a, and the internal combustion engine is started. At this time, while the engine is stopped, the fuel pressure is adjusted to a predetermined pressure or less to prevent fuel leakage from the injector 12, so that the startability when the IG switch 33 is turned on is improved.

When the IG switch 33 is turned on.
Predetermined time t after_cSeconds (1.5 seconds in this embodiment)
Later, the engine speed becomes idle. Also when
Interval T _Three, The control circuit 45 turns on the negative pressure control valve 41.
The magnetic coil 42 is excited. Thus, the electromagnetic coil 42
When energized, the pressure in the pressure supply line 39 will be
It changes from 1 to the introduced negative pressure.

Thus, the fuel discharged from the fuel pump 16 is supplied to each injector 12 through the fuel supply line 15, and excess fuel not injected from the injector 12 is discharged to the fuel pressure relief chamber 21 of the regulator 17. Then, the fuel is returned to the fuel tank 24 via the return pipe 23. Therefore, after the internal combustion engine is started, the fuel pumped by the fuel pump 16 enters a normal state in which the fuel is circulated through the fuel supply line 15, the fuel pressure relief chamber 21, the return line 23, and the fuel tank 24.

FIG. 3 is a configuration diagram showing a schematic configuration of a first modification of the present invention. Note that, in FIG. 3, FIG.
The same parts as those described above are denoted by the same reference numerals and description thereof will be omitted. In the fuel supply device for an internal combustion engine shown in FIG. 3, one end of a negative pressure introduction pipe line 51 is connected to a negative pressure control valve 32. The other end of the negative pressure introducing pipe 51 is connected to a vacuum tank 52.
Is communicated to. In addition, the vacuum tank 52 includes:
A branch line 53 branched from the air supply line 11 is communicated. The branch pipe 53 is provided with a check valve 54 for preventing the air introduced into the vacuum tank 52 from flowing back to the air supply pipe 11.

When the internal combustion engine is started, the valve element 36 of the negative pressure control valve 32 is attracted by the electromagnetic force of the electromagnetic coil 34 to close the negative pressure introducing line 51 and to close the pressure introducing line 31. Open. Therefore, the negative pressure of the air supply line 11 is introduced into the diaphragm chamber 20 of the regulator 17 via the pressure introducing line 31, the negative pressure control valve 32, and the pressure introducing line 39.

Thus, the diaphragm valve 29 of the regulator 17 is displaced in the valve opening direction by being pressed by the fuel pressure of the fuel supply pipe 15. Therefore, the fuel pump 1
The fuel pumped by 6 circulates through the fuel supply line 15, the fuel pressure relief chamber 21, the return line 23, and the fuel tank 24. In addition, a branch pipe 53 is also provided in the vacuum tank 52.
, A negative pressure in the air supply line 11 is introduced. Then, when the energization of the electromagnetic coil 34 of the negative pressure control valve 32 is stopped, the valve element 36 operates to the position where the pressure introducing pipe 31 is closed by the spring force of the spring 43 and the negative pressure introducing pipe 51 is opened. Is done. Thereby, the vacuum tank 52
Is in communication with the diaphragm chamber 20 of the regulator 17 via the negative pressure introducing pipe 51, the negative pressure control valve 32, and the pressure introducing pipe 39.

Accordingly, the negative pressure of the vacuum tank 52 is introduced into the diaphragm chamber 20, and the pressure in the diaphragm chamber 20 becomes lower. Therefore, immediately after the engine is stopped, the diaphragm valve 29 of the regulator 17 is displaced to a position where the end of the fuel supply pipe 15 is closed, but the pressure for pressing the diaphragm valve 29 to the valve closing position is weak.

Therefore, when the fuel pressure in the fuel supply line 15 becomes higher than a predetermined pressure, the diaphragm valve 29 is displaced in a direction to open the fuel supply line 15 to release the excess fuel pressure to the return line 23, thereby injecting the fuel into the injector 23. 12 prevents fuel leakage. In this manner, the holding force for pressing the diaphragm valve 29 to the closed position can be set by the ratio between the volume of the vacuum tank 52 and the volume of the diaphragm chamber 20 of the regulator 17, so that the volume of the vacuum tank 52 can be changed. Thus, the fuel pressure can be adjusted to an arbitrary pressure.

FIG. 4 is a time chart for explaining the control operation of the first modification shown in FIG. 4, when the IG switch 33 is operated from ON to OFF at time T _1, the control circuit 45 stops the engine. Along with this, the pressure in the air supply passage 11 gradually changes from negative pressure to atmospheric pressure. Since the fuel pump 16 has also stopped when the engine rotation has stopped, the check valve 18 closes the upstream end of the fuel supply pipe 15.

Then, the control circuit 45 controls the IG switch 3
At the same time when the switch 3 is turned off, the power supply to the electromagnetic coil 42 of the negative pressure control valve 41 is stopped. As a result, the valve element 36 of the negative pressure control valve 32 operates at a position where the pressure introduction pipe 31 is closed, and opens the negative pressure introduction pipe 51. However, in the first modification, at the same time when the engine is stopped, the vacuum tank 52 and the diaphragm chamber 20 of the regulator 17 communicate with each other via the negative pressure introduction pipe 51, the negative pressure control valve 32, and the pressure introduction pipe 39. And the diaphragm chamber 20
Negative pressure is lower.

Therefore, when the fuel pressure in the fuel supply line 15 is equal to or lower than the predetermined pressure, the diaphragm valve 29 is kept at the closed position to prevent the fuel pressure from lowering. Further, when the fuel pressure in the fuel supply pipe 15 becomes equal to or higher than the predetermined pressure, the negative pressure of the diaphragm chamber 20 is lower, so that the diaphragm valve 29 opens more quickly than the conventional one. Therefore, the fuel in the fuel supply line 15 flows out to the return line 23, and the fuel pressure decreases to an appropriate pressure. As a result, fuel leakage from the injector 12 is prevented. That is, since it is possible to prevent the fuel from being excessively supplied at the time of starting and becoming difficult to ignite as the fuel pressure is maintained, the startability of the internal combustion engine is further improved.

FIG. 5 is a time chart for explaining another operation control of the first modification shown in FIG. 5, when the IG switch 33 is operated from ON to OFF at time T _1, the control circuit 45 stops the engine. Along with this, the pressure in the air supply passage 11 gradually changes from negative pressure to atmospheric pressure. Since the fuel pump 16 has also stopped when the engine rotation has stopped, the check valve 18 closes the upstream end of the fuel supply pipe 15.

The control circuit 45 controls the IG switch 3
3 is turned off, a preset delay time t _d
The power supply to the electromagnetic coil 42 of the negative pressure control valve 41 is continued until elapses. Therefore, immediately after the engine stops, the air supply system 1
A pressure of 1 (atmospheric pressure) is introduced into the diaphragm chamber 20. As a result, the holding force for pressing the diaphragm valve 29 of the regulator 17 to the valve closing position becomes stronger than in the above case.

Therefore, since the downstream end of the fuel supply line 15 is closed by the diaphragm valve 29, the fuel pressure in the fuel supply line 15 increases. And the control circuit 4
5, when the delay time t _d has elapsed since the IG switch 33 was turned off, the electromagnetic coil 42 of the negative pressure control valve 41
Stop supplying power to As a result, the valve element 36 of the negative pressure control valve 32 operates at a position where the pressure introduction pipe 31 is closed, and opens the negative pressure introduction pipe 51. Therefore, the vacuum tank 52 and the diaphragm chamber 20 of the regulator 17 communicate with each other via the negative pressure introducing pipe 51, the negative pressure control valve 32, and the pressure introducing pipe 39. Thus, the negative pressure in the diaphragm chamber 20 becomes lower.

On the other hand, the fuel pressure in the fuel supply line 15 is boosted during the above as the delay time t _d. Therefore, when the negative pressure of the vacuum tank 52 is introduced into the diaphragm chamber 20, the diaphragm valve 29 is opened by the fuel pressure of the fuel supply pipe 15. Therefore, the fuel in the fuel supply line 15 flows out to the return line 23, and the fuel pressure decreases to an appropriate predetermined pressure. As a result, fuel leakage from the injector 12 is prevented.

That is, since it is possible to prevent the fuel from being excessively supplied at the time of starting and becoming difficult to ignite as the fuel pressure is maintained, the startability of the internal combustion engine is further improved. FIG. 6 is a configuration diagram showing a schematic configuration of Modification 2 of the present invention. In FIG. 6, the same parts as those in FIGS. In the fuel supply device for an internal combustion engine shown in FIG. 6, a vacuum tank 55 is arranged in the pressure introducing pipe 39 in the configuration shown in FIG. The vacuum tank 55 is simultaneously opened when the valve body 44 of the negative pressure control valve 41 opens and the negative pressure from the air supply line 11 is supplied to the diaphragm chamber 20 via the pressure introducing line 39. The pressure is accumulated.

Since the vacuum tank 55 is always in communication with the diaphragm chamber 20, the diaphragm tank 2
It acts to buffer a zero pressure change. FIG. 7 is a time chart for explaining the operation control of the second modification shown in FIG. 7, when the IG switch 33 is operated from ON to OFF at time T _1, the control circuit 45,
Stop engine rotation. Accordingly, the air supply system 11
Changes gradually from negative pressure to atmospheric pressure. Since the fuel pump 16 has also stopped when the engine rotation has stopped, the check valve 18 closes the upstream end of the fuel supply pipe 15.

The control circuit 45 controls the IG switch 3
The power supply to the electromagnetic coil 42 of the negative pressure control valve 41 is stopped with _a delay of a minute time ta after the switch 3 is turned off. Accordingly, the valve body 44 of the negative pressure control valve 41 performs a valve closing operation by the spring force of the spring 25. Therefore, the pressure supply line 39
In addition, the vacuum tank 55 is in a state where the negative pressure introduced from the air supply passage 11 is contained. Therefore, the diaphragm chamber 20 of the regulator 17 connected to the pressure supply pipe 39 and the vacuum tank 55 is kept in a state where a negative pressure smaller than the negative pressure when the engine is started is introduced.

Therefore, the pressure in the diaphragm chamber 20 is
The negative pressure corresponding to the time when the negative pressure control valve 41 performs the valve closing operation is maintained. When the negative pressure control valve 41 performs a valve closing operation,
Since the negative pressure is accumulated in the vacuum tank 55 having a sufficient volume, the pressure in the diaphragm chamber 20 can be kept constant regardless of air leakage from the valve body 44. When the negative pressure control valve 41 performs the valve closing operation with _a delay of the minute time ta, the pressure of the diaphragm chamber 20 slightly increases and the fuel pressure decreases. When the engine is stopped, the pressure in the diaphragm chamber 20 of the regulator 17 is maintained at a negative pressure. Therefore, when the fuel in the fuel supply line 15 is excessively pressurized, the diaphragm valve 19 of the regulator 17 is activated. The valve opens. Therefore, the fuel supply line 1
The fuel pressure 5 is adjusted to a predetermined pressure or less according to the negative pressure of the diaphragm chamber 20 and the spring force of the spring 25.

As a result, while the engine is stopped, the injector 1
2 can be prevented from leaking to the intake manifold 11a. As a result, when starting the internal combustion engine,
It is possible to prevent too much fuel for the air supplied from the air supply passage 11. Also, at time T _2, when the IG switch 33 is operated to ON, the control circuit 45 (in this embodiment, 0.5 seconds) minute time t _b energization to the electromagnetic coil 42 only the negative pressure control valve 41 I do. Thus, when the electromagnetic coil 42 is momentarily excited, the pressure supply pipe 39 and the vacuum tank 55 are changed to the atmospheric pressure by the air introduced from the air supply path 11. Thus, the pressure supply line 3
Atmospheric pressure is sealed in the vacuum tank 9 and the vacuum tank 55. Therefore, since the vacuum tank 55 is at atmospheric pressure, the pressure in the diaphragm chamber 20 is stably maintained at atmospheric pressure.

As a result, the downstream end of the fuel supply pipe 15 is closed by the diaphragm valve 19 of the regulator 17. At the same time, the fuel pump 16 is started, so that the fuel pressure in the fuel supply line 15 increases. The pressure (surge tank pressure) air supply pathway 11, starts to change from atmospheric pressure to a negative pressure after the short time t _b. Therefore, the injector 12 moves from the intake manifold 11
Mist fuel is injected from a, and the internal combustion engine is started. At this time, while the engine is stopped, the fuel pressure is adjusted to a predetermined pressure or less to prevent fuel leakage from the injector 12, so that the startability when the IG switch 33 is turned on is improved.

When the IG switch 33 is turned on.
Predetermined time t after_cSeconds (1.5 seconds in this embodiment)
Later, the engine speed becomes idle. Also when
Interval T _Three, The control circuit 45 turns on the negative pressure control valve 41.
The magnetic coil 42 is excited. Thus, the electromagnetic coil 42
When energized, the pressure in the pressure supply line 39 will be
It changes from 1 to the introduced negative pressure.

Thus, the fuel discharged from the fuel pump 16 is supplied to each injector 12 through the fuel supply line 15, and excess fuel not injected from the injector 12 is discharged to the fuel pressure relief chamber 21 of the regulator 17. Then, the fuel is returned to the fuel tank 24 via the return pipe 23. Therefore, after the internal combustion engine is started, the fuel pumped by the fuel pump 16 enters a normal state in which the fuel is circulated through the fuel supply line 15, the fuel pressure relief chamber 21, the return line 23, and the fuel tank 24.

In the above embodiment, a three-way valve such as the negative pressure control valve 36 or an open / close valve such as the negative pressure control valve 41 is used as the switching valve. May be used. Further, in the above embodiment, the configuration in which the negative pressure control valves 36 and 41 are operated with a predetermined time delay after the IG switch 33 is turned on or off has been described as an example. However, this delay time can be set arbitrarily. Of course.

[0060]

As described above, according to the first aspect of the present invention, when the internal combustion engine is stopped, the negative pressure introduced into the pressure introducing line is temporarily maintained. Therefore, when the fuel pressure in the fuel supply line becomes equal to or higher than a predetermined value after the engine stops, the pressure control valve can cause the fuel in the fuel supply line to flow out to the return line. This makes it possible to reduce the fuel pressure after the engine is stopped to an appropriate predetermined value or less, thereby preventing the fuel from leaking from the injector. Therefore, while the engine is stopped, the fuel pressure is adjusted to a predetermined pressure or less, and fuel leakage from the injector is prevented, so that the startability after the engine is once stopped can be improved.

According to the second aspect of the present invention, when it is detected that the internal combustion engine is in the starting state, the negative pressure of the fuel supply line is supplied to the pressure chamber of the pressure control valve, and the internal combustion engine is stopped. When the state is detected, the negative pressure accumulated in the vacuum tank is supplied to the pressure chamber of the pressure control valve.
When the fuel pressure in the fuel supply line becomes higher than a predetermined pressure after the engine is stopped, the pressure control valve can cause the fuel in the fuel supply line to flow out to the return line. This makes it possible to reduce the fuel pressure after the engine is stopped to an appropriate predetermined value or less,
Leakage of fuel from the injector can be prevented. Therefore, while the engine is stopped, the fuel pressure is adjusted to a predetermined pressure or less, and fuel leakage from the injector is prevented, so that the startability after the engine is once stopped can be improved.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a schematic configuration of a fuel supply device for an internal combustion engine according to one embodiment of the present invention.

FIG. 2 is a time chart for explaining the operation of the fuel supply device for an internal combustion engine shown in FIG. 1;

FIG. 3 is a configuration diagram showing a schematic configuration of a first modification of the present invention.

FIG. 4 is a time chart for explaining operation control of Modification Example 1 shown in FIG. 3;

FIG. 5 is a time chart for explaining another operation control of the first modification shown in FIG. 3;

FIG. 6 is a configuration diagram illustrating a schematic configuration of Modification Example 2 of the present invention.

FIG. 7 is a time chart for explaining the operation control of Modification 2 shown in FIG. 6;

FIG. 8 is a configuration diagram for explaining a first conventional example of a fuel supply device for an internal combustion engine.

FIG. 9 is a configuration diagram for explaining a conventional example 2 different from the conventional example 1 shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Air supply system line 12 Injector 14 Throttle valve 15 Fuel supply line 16 Fuel pump 17 Regulator 19 Diaphragm valve 20 Diaphragm room 21 Fuel pressure relief chamber 23 Return line 24 Fuel tank 31 Pressure introduction line 32, 41 Negative pressure control valve 33 Ignition switch 34, 42 Electromagnetic coil 36, 44 Valve body 39 Pressure supply line 45 Control circuit 51 Negative pressure introduction line 52, 55 Vacuum tank

Claims (2)

[Claims] 1. An injector for injecting fuel into an air supply system, a pump for supplying fuel to the injector, a fuel supply pipe for supplying fuel pressurized by the pump to the injector, and A return line for returning excess fuel that has not been injected to the fuel tank, a pressure introduction line for introducing a negative pressure of the air supply system, and a negative pressure introduced via the pressure introduction line. A valve device for opening the valve so that the pressure in the fuel supply line becomes a predetermined pressure and causing the fuel to flow out to the return line.The fuel supply device for an internal combustion engine, wherein when the internal combustion engine is stopped, A fuel supply device for an internal combustion engine, comprising closing means for closing the pressure introduction pipe so as to temporarily hold the negative pressure introduced into the pressure introduction pipe. 2. An injector for injecting fuel into an air supply system, a pump for supplying fuel to the injector, a fuel supply pipe for supplying fuel pressurized by the pump to the injector, and A return line for returning excess fuel that has not been injected to the fuel tank, a pressure introduction line for introducing a negative pressure of the air supply system, and a negative pressure introduced via the pressure introduction line. A valve device for opening the valve so that the pressure of the fuel supply line becomes a predetermined pressure and allowing the fuel to flow out to the return line.The fuel supply device for an internal combustion engine, wherein the negative pressure of the fuel supply line is A vacuum tank for accumulating pressure, and supplying a negative pressure of the air supply line to the pressure chamber of the valve device when it is detected that the internal combustion engine is in an activated state, and detecting that the internal combustion engine is in a stopped state. When said fuel A switching valve for supplying a negative pressure accumulated in the vacuum tank to a pressure chamber of the valve device so that a fuel pressure in a supply pipe is adjusted to a predetermined pressure. Feeding device.