JP2795137B2 - Fuel supply device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel supply apparatus suitable for use in a direct injection type internal combustion engine, and more particularly to a fuel supply apparatus for an internal combustion engine capable of performing fuel injection at a relatively high fuel pressure. About.

[0002]

2. Description of the Related Art A diesel engine is widely known as a so-called direct injection type internal combustion engine or a direct injection type internal combustion engine (direct injection type internal combustion engine) in which fuel is injected in a cylinder. However, in recent years, an in-cylinder injection type engine has also been proposed for a spark ignition type engine (generally, a gasoline engine is used, and is hereinafter referred to as a gasoline engine).

[0003] In such a direct injection internal combustion engine, in order to improve the performance of the engine and reduce the exhaust gas, there is a tendency that the fuel injection pressure is increased to atomize the fuel spray and shorten the fuel injection period. Further, in an engine having a supercharging mechanism, a high fuel injection pressure corresponding to the supercharging pressure is required at the time of supercharging. Therefore, the fuel supply device in the in-cylinder injection type internal combustion engine is configured to obtain such a sufficiently high fuel injection pressure (for example, about several tens of atmospheres).

For example, FIGS. 5 and 6 schematically show the configuration of a fuel supply device for an internal combustion engine that has been conventionally proposed as a device capable of obtaining such a high fuel injection pressure. 5 and 6, reference numeral 1 denotes a fuel injection valve;
Is a fuel tank, 3 is a fuel passage provided between the fuel injection valve 1 and the fuel tank 2, 4 is a low-pressure fuel pump provided at an upstream portion of the fuel passage 3 on the fuel tank 2 side, and 5 is a low-pressure fuel pump. This is a high-pressure fuel pump provided between the fuel pump and the fuel injection valve 1. Reference numerals 6 and 7 denote a fuel filter provided at the inlet of the fuel passage, 8 denotes a check valve, 9 denotes a valve low pressure control valve as low pressure control means, and 10 denotes a high pressure control valve as high pressure control means. 21 is a cylinder, 22 is a piston, 22A is a piston rod, 23 is a crankshaft, 24 is a combustion chamber, 25 is a cylinder head, 26 is an intake passage, 27 is a spark plug, and 28 is an exhaust passage.

[0005] In such a fuel supply device, the fuel pressurized to some extent by the low-pressure fuel pump 4 is supplied to the high-pressure fuel pump 5.
Further, the pressure of the fuel is increased to a predetermined pressure. At this time, the discharge pressure from the low-pressure fuel pump 4 is stabilized to a predetermined range by the low-pressure control valve 9, and the discharge pressure from the high-pressure fuel pump 4 is further stabilized to a predetermined range by the high-pressure control valve 10.

Since the fuel injection pressure does not always have to be high to a predetermined pressure, a high fuel injection pressure is applied in an operation region where the intake pressure is high, for example, in an internal combustion engine disclosed in Japanese Patent Application Laid-Open No. 62-237057. However, there has been proposed a fuel pump in which the fuel injection pressure is kept low in an operation region where the intake pressure is low to reduce the load on the fuel pump.

[0007]

By the way, it is conceivable to employ either an engine driven pump or an electric pump as the fuel pumps 4 and 5 as described above.
When an electric pump is used for the high-pressure pump, the pump efficiency is reduced and the cost is increased. Therefore, it is generally considered that an engine-driven fuel pump is used for the high-pressure fuel pump 5. On the other hand, when the electric pump is used for the low-pressure pump, the above-described disadvantages in terms of pump efficiency and cost are reduced, and the advantage of the electric pump that a stable discharge pressure can be obtained is utilized. It is conceivable to employ an electric type.

However, since the discharge pressure of the engine-driven pump depends on the engine speed, if the high-pressure fuel pump 5 is of an engine-driven type, the engine speed is low when the engine is started and the discharge of the high-pressure pump is low. There is a problem that the pressure becomes extremely low and the fuel pressure becomes unstable. That is, even if an electric pump is adopted as the low-pressure fuel pump 4 so that the fuel can always be pressurized to a predetermined low-pressure level irrespective of the engine rotation, the low-pressure fuel pump 4 and the fuel injection The high-pressure fuel pump 5 between the valve 1 prevents the fuel flow, and the fuel flow rate and the fuel pressure at the fuel injection valve 1 do not reach the discharge flow rate and the discharge pressure of the low-pressure fuel pump 4. I will. For this reason, the required fuel flow rate and fuel pressure at the time of starting the engine cannot be secured, and the rotation of the engine is not easily increased smoothly, and the engine may stall.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and provides a predetermined fuel flow rate and a predetermined fuel pressure even when the internal combustion engine is started, so that the rotation of the internal combustion engine can be quickly and smoothly performed after the start of the internal combustion engine. It is an object of the present invention to provide a fuel supply device for an internal combustion engine that can increase the speed.

[0010]

According to a first aspect of the present invention, there is provided a fuel supply system for an internal combustion engine, comprising: a fuel passage provided between a fuel injection valve and a fuel tank in the internal combustion engine; A low-pressure fuel pump provided in an upstream portion of the passage; and a high-pressure fuel pump provided between the low-pressure fuel pump and the fuel injection valve in the fuel passage, and a fuel passage upstream of the high-pressure fuel pump. A bypass passage connecting the portion and the downstream fuel passage portion, and a check valve for passing fuel only from the upstream side to the downstream side of the fuel passage is provided in the bypass passage. And

According to a second aspect of the present invention, there is provided a fuel supply device for an internal combustion engine according to the first aspect, wherein a fuel passage portion downstream of the low-pressure fuel pump and upstream of the high-pressure fuel pump is provided. High pressure control means for controlling the pressure of the fuel discharged from the low pressure fuel pump is provided, and high pressure control means for controlling the pressure of the fuel discharged from the high pressure fuel pump is provided in a fuel passage downstream of the high pressure fuel pump. Is provided.

[0012]

In the fuel supply device for an internal combustion engine according to the first aspect of the present invention, in a region where the high-pressure fuel pump does not operate sufficiently and hinders the fuel discharged by the low-pressure fuel pump, the fuel in the fuel tank may be prevented. Is pressurized by the low-pressure fuel pump, is sent to the upstream portion of the high-pressure fuel pump through the fuel passage, and then flows into the bypass passage. Since the check valve provided in this bypass passage allows fuel to pass only from the upstream side to the downstream side of the fuel passage, the fuel pressurized by the low-pressure fuel pump is not hindered, The fuel is supplied to the fuel injection valve while bypassing the high-pressure fuel pump, and fuel is injected from the fuel injection valve at a pressure corresponding to the discharge pressure of the low-pressure fuel pump. Accordingly, in a region where the high-pressure fuel pump does not operate sufficiently and hinders the fuel discharged from the low-pressure fuel pump, the fuel pressurized by the low-pressure fuel pump bypasses the high-pressure fuel pump through the bypass passage. The fuel is supplied to the fuel injection valve, and fuel is injected from the fuel injection valve according to the discharge flow rate and the discharge pressure of the low-pressure fuel pump.

When the discharge pressure of the high-pressure fuel pump increases, the fuel in the fuel tank is pressurized by the low-pressure fuel pump and sent to the high-pressure fuel pump. The fuel is injected from the fuel injection valve at a high pressure corresponding to the discharge pressure of the high-pressure fuel pump.
At this time, the pressure on the downstream side of the high-pressure fuel pump becomes significantly higher than that on the upstream side, and there is a possibility that the fuel flows backward on the upstream side to the downstream side via the bypass passage. Since this is prevented, a high discharge pressure of the high-pressure fuel pump is sufficiently ensured.

According to a second aspect of the present invention, the fuel pressure discharged from the low-pressure fuel pump is controlled by the low-pressure control means, and the high-pressure control means controls the fuel pressure discharged from the high-pressure fuel pump. The discharged fuel pressure is controlled.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIGS. 1 and 2 show a fuel supply system for an internal combustion engine as a first embodiment of the present invention, and FIG. FIG. 2 is a graph showing the characteristics of the output (discharge flow rate) of the fuel pump, and FIG. 3 is a schematic diagram showing a fuel supply device for an internal combustion engine as a second embodiment of the present invention. FIG. 4 is a schematic configuration diagram showing a fuel supply device for an internal combustion engine as a third embodiment of the present invention.

First, the first embodiment will be described. This fuel supply device for an internal combustion engine is provided in a gasoline four-stroke engine as an internal combustion engine, particularly, in a direct injection gasoline engine that directly injects fuel into a cylinder. As shown in FIG. 1, a fuel passage 3 communicating between the fuel injection valve 1 and the fuel tank 2 is provided with a low-pressure fuel pump 4 and a high-pressure fuel pump 5. The fuel passage 3
Is composed of a supply path 3A for supplying fuel from the fuel tank 2 to the fuel injection valve 1, and a return path 3B for returning fuel not injected by the fuel injection valve 1 to the fuel tank 2.

The relationship between the main parts of the fuel supply device for an internal combustion engine and the engine is the same as that shown in FIG. The low-pressure fuel pump 4 is connected to the feed passage 3A of the fuel passage 3.
A feed pump provided in the fuel tank 2 at an upstream portion of the fuel tank 2, wherein an electric pump is used. In operation, the fuel in the fuel tank 2 is filtered downstream of the feed passage 3 A while being filtered by the fuel filter 6. It is designed to be driven to the side.
The pressurization of the fuel by the low-pressure fuel pump 4 at this time is performed from an atmospheric pressure state to several atmospheric pressures. The low-pressure fuel pump 4 is started when the engine is started, and is stopped when the engine is stopped. Of course, the low-pressure fuel pump 4 can generate a predetermined discharge pressure without depending on the rotation speed of the engine. Has become.

The high-pressure fuel pump 5 pressurizes the fuel discharged from the low-pressure fuel pump 4 to about several tens of atmospheres. The check valve 8 and the fuel filter 7 are interposed, the discharge pressure from the low-pressure fuel pump 4 is maintained by the check valve 8, and the fuel is further filtered by the fuel filter 7. This high pressure fuel pump 5
For example, an engine-driven pump such as a reciprocating compression pump (hereinafter referred to as an engine-driven pump) is more advantageous as a high-pressure pump than an electric pump in terms of pump efficiency and cost.
Of course, it operates directly in conjunction with the operation of the engine, and generates a discharge pressure according to the rotation speed of the engine.

FIG. 2 shows an example of the output characteristics (discharge flow rate) of the fuel pumps 4 and 5 under the condition that the discharge pressure is kept constant. The flow characteristics are shown, and a straight line C shows the discharge flow characteristics of the low-pressure fuel pump 4. In each case of the straight lines A and B, the setting of the lift cam amount required for driving the high-pressure fuel pump 5 is different. In the case of B, the lift cam amount and the pump output are larger than in the case of A. I have. The actual discharge pressures of the fuel pumps 4 and 5 are determined by such discharge flow characteristics and the low pressure control valve (low pressure regulator) 9 as low pressure control means and the high pressure control valve (high pressure regulator) 10 as low pressure control means described later. Since it is determined by the flow resistance, the discharge flow characteristic in this case cannot be read as the discharge pressure characteristic as it is, but the discharge pressure characteristic almost corresponds to the discharge flow characteristic. Therefore, as shown in FIG. 2, the electric low-pressure fuel pump 4 can generate a predetermined discharge pressure (discharge flow rate) without depending on the engine speed, and the engine-driven high-pressure fuel pump 5 can generate the engine speed. It can be seen that the discharge pressure (discharge flow rate) is generated in proportion to.

The feed passage 3A of the fuel passage 3 and the return passage 3
B, that is, a portion of the feed passage 3A downstream of the fuel filter 7 upstream of the high-pressure fuel pump 5 and the return passage 3B.
A low-pressure control valve 9 for adjusting the discharge pressure from the low-pressure fuel pump 4 to a set pressure (for example, 3 atm) is provided between the low-pressure fuel pump 4 and the most downstream portion. The low-pressure control valve 9 is closed until the discharge pressure from the low-pressure fuel pump 4 exceeds a set pressure (for example, 3 atm). When the discharge pressure exceeds the set pressure, the fuel for the excess pressure is not used. By directly returning the fuel to the fuel tank 2, the pressure of the fuel supplied to the high-pressure fuel pump 5 is stabilized near the set pressure. Of course, the low-pressure fuel pump 4 is set so that its discharge pressure is equal to or higher than the set pressure so that the above-mentioned set pressure is obtained.

Also, a portion immediately downstream of the fuel injection valve 1, that is,
A high-pressure control valve 10 for adjusting the discharge pressure from the high-pressure fuel pump 5 to a set pressure (for example, 50 atm) is provided at the most upstream portion of the return path 3B of the fuel passage 3. The high-pressure control valve 10 is closed until the discharge pressure from the high-pressure fuel pump 5 exceeds a set pressure (for example, 50 atm). The fuel is returned to the fuel tank 2 and the fuel pressure in the fuel injection valve 1 is stabilized at a predetermined pressure.

The fuel supply device has a fuel passage 3
The bypass passage (hereinafter, referred to as the “passage”) connects the upstream portion and the downstream portion of the high-pressure fuel pump 5 so that the fuel passing through the supply passage 3A can be supplied to the fuel injection valve 1 bypassing the high-pressure fuel pump 5. A first bypass passage) is provided.
Further, the first bypass passage 11 is provided with a check valve 12 that allows fuel to pass only from the upstream side to the downstream side of the feed path 3A. If the high-pressure fuel pump 5 does not operate sufficiently and the fuel pressure is lower on the downstream side than on the upstream side of the high-pressure fuel pump 5, the check valve 12
1, the first bypass passage 11 is closed when the high-pressure fuel pump 5 is sufficiently operated and the fuel pressure is higher on the downstream side than on the upstream side of the high-pressure fuel pump 5.

Further, the fuel supply device is provided with a high pressure control valve 1 so that the fuel in the fuel injection valve 1 can be discharged to the fuel tank 2 by bypassing the high pressure control valve 10.
A bypass passage (hereinafter, referred to as a second bypass passage) 13 that connects the upstream side portion and the downstream side portion 0 is provided. The second bypass passage 13 is for discharging vapor (bubbles) contained near the fuel injection valve 1 in the fuel passage 3 at an early stage of engine start. Therefore, in the second bypass passage 13, an electromagnetic switching valve 14 that opens and closes the second bypass passage 13 and the fuel pressure upstream of the second bypass passage 13, that is, the fuel pressure of the fuel injection valve 1 can be maintained at a predetermined pressure. A fuel pressure holding mechanism 15 is provided.

The solenoid-operated directional control valve 14 opens the second bypass passage 13 when the electric power is received, and closes the second bypass passage 13 when the electric power is shut off. Then, when the ignition key switch 16 is operated to the starter position, the ignition key switch 16 is actuated in conjunction with this to open the second bypass passage 13, thereby stopping when the vapor contained in the vicinity of the fuel injection valve 1 is completely discharged. And the second
The bypass passage 13 is closed.

When the vapor discharge operation is continued for a certain period of time by opening the second bypass passage 13, the discharge of the vapor near the fuel injection valve 1 is almost completed, but the discharge of the vapor is completed. The time until can be estimated based on, for example, experiments. In this embodiment, based on the vapor discharge completion time that can be predicted in advance,
The vapor discharge operation is completed, that is, the electromagnetic switching valve 14 is stopped. For this purpose, for example, the electromagnetic switching valve 14 itself may be provided with a timer that operates at the same time as the activation of the electromagnetic switching valve 14 and a mechanism that stops the electromagnetic switching valve 14 when the timer elapses a set time. Good. Also, for example, when the controller is configured to electronically control the power supplied to the electromagnetic switching valve 14 by a controller, the controller supplies power to the electromagnetic switching valve 14 based on a starter-on signal from the ignition key switch 16, The configuration may be such that the attached timer is started and the supply of power to the electromagnetic switching valve 14 is stopped when a signal indicating that the set time has elapsed is received from the timer.

It should be noted that the time for the above-described vapor discharge operation, that is, the opening time of the electromagnetic switching valve 14, is generally assumed to be sufficient for a short engine (within several seconds) after the engine is started. The fuel pressure holding mechanism 15 is provided for obtaining a fuel pressure at least close to the set pressure controlled by the low pressure control valve 9 immediately after the start of the engine even if the second bypass passage 13 is open. In this embodiment, a so-called fixed throttle, which only narrows the inner diameter of the fuel passage 3, is provided as the fuel pressure holding mechanism 15.

Since the fuel supply device for an internal combustion engine according to the first embodiment of the present invention is configured as described above, when the ignition key switch 16 is set to the starter ON position and the engine is started, the engine starts. (That is,
At the same time as cranking, the low-pressure fuel pump 4 and the high-pressure fuel pump 5 operate. The low-pressure fuel pump 4, as shown by the straight line C in FIG. 2, immediately reaches an output pressure state of a predetermined pressure (several atmospheric pressures) after starting. However, immediately after starting the engine, the rotation of the engine does not increase. In No. 5, as shown in FIG. 2, a sufficient discharge pressure is not generated.

For this reason, immediately after the engine is started, the high-pressure fuel pump 5 causes the resistance of the flow of the fuel flow in the fuel passage 3 due to the discharge pressure from the low-pressure fuel pump 4. Since the fuel is supplied to the fuel injection valve 1 through the first bypass passage 11 provided in parallel with the high-pressure fuel pump 5, the fuel is supplied from the fuel injection valve 1 to the low-pressure control valve 9.
The fuel injection can be performed at a fuel pressure about the pressure adjusted by the above.

That is, the check valve 12 is provided in the first bypass passage 11, and the check valve 12 is provided when the fuel pressure is lower on the downstream side than on the upstream side of the high-pressure fuel pump 5.
Since the first bypass passage 11 is opened, if the high-pressure fuel pump 5 does not generate a sufficient discharge pressure, the fuel is supplied to the fuel injection valve 1 at a pressure on the order of the adjustment level of the low-pressure control valve 9.

In general, immediately after the start of the engine, the amount of fuel required for combustion is small, so that the pulse width of the fuel injection is short, and the pulse timing of the fuel injection is the same as in the conventional multipoint injection (MPI). This is performed only during the intake stroke, so that even if the fuel pressure is about the adjustment pressure level of the low-pressure control valve 9, if the fuel pressure is stable, the rotation of the engine can be smoothly increased. . As a result, as the engine speed increases, the discharge flow rate of the high-pressure fuel pump 5 increases as shown by the straight lines A and B in FIG. 2, and the discharge pressure of the high-pressure fuel pump 5 also increases smoothly.

When the high-pressure fuel pump 5 starts operating to some extent, the fuel pressure becomes higher on the downstream side than on the upstream side of the high-pressure fuel pump 5, and the check valve 12 closes the first bypass passage 11. As a result, the discharge pressure of the high-pressure fuel pump 5 is increased without any loss, so that the fuel pressure on the downstream side of the high-pressure fuel pump 5 is increased.

As a result, the discharge pressure of the high-pressure fuel pump 5 rises to a sufficient level, and fuel can be injected from the fuel injection valve 1 at a high fuel pressure, which is approximately equal to the adjustment pressure of the high-pressure control valve 10. In this way, for example, in an in-cylinder injection type internal combustion engine, it is required to shorten the fuel injection period (that is, the pulse width of the fuel injection) while smoothly increasing the engine rotation speed immediately after the engine start. In addition, a high fuel injection pressure required according to the supercharging pressure at the time of supercharging can be obtained.

On the other hand, for example, in an internal combustion engine for an automobile,
After the engine stops, the temperature rise in the engine room caused by the stop of the engine cooling system and the pressure control valves 9 and 1
In the fuel passage 3, vapor (bubbles) is generated in the fuel passage 3 due to the fuel leak in the fuel injection valve 1 or 0, and the fuel supply is started with the vapor contained in the fuel passage 3 when the engine is started next time. In particular, the vapor present near the fuel injection valve 1 causes a delay or variation in the rise of the fuel pressure to be injected, or causes idle injection from the fuel injection valve 1, making it difficult to control the fuel injection.

The vapor existing in the vicinity of the fuel injection valve 1 flows through the return path 3B of the fuel passage 3 when the fuel starts flowing through the fuel passage 3 by starting the fuel supply device. The high pressure control valve 10 provided in the return path 3B closes if the fuel pressure is not high, and shuts off the flow of fuel. Therefore, vapor discharge is also hindered.
A second bypass passage 13 is provided in parallel with the high-pressure control valve 10, and the electromagnetic switching valve 1 opens and closes the second bypass passage 13.
4 is open for a predetermined period after the engine is started, so that the fuel is supplied through the second bypass passage 13 to the high-pressure control valve 10.
Circulates downstream of the return path 3B while detouring.

With this fuel flow, the vapor contained in the fuel passage 3 near the fuel injection valve 1 is discharged to the outside of the fuel passage 3. As described above, even when the second bypass passage 13 is open, the fixed throttle 15 as the fuel pressure holding mechanism controls the fuel pressure near the fuel injection valve 1 to be controlled at least by the low pressure control valve 9. Since the pressure is maintained at a value close to the pressure, the fuel injection pressure from the fuel injection valve 1 is ensured at the time of starting the engine, while the vapor is being discharged.

Accordingly, a certain amount of fuel injection pressure can be obtained without causing delays and variations in the rise of fuel pressure caused by the vapor immediately after the start of the engine, phenomena such as idle injection, etc. Therefore, it is possible to smoothly increase the engine rotation speed while maintaining good engine combustion, so that the practicality of, for example, an in-cylinder injection type engine can be greatly improved.

The electromagnetic switching valve 14 for opening and closing the second bypass passage 13 is closed after a predetermined period (relatively short time) has elapsed after the engine has been started and the vapor has been sufficiently discharged. After that, the fuel pressure can be increased to the pressure controlled by the high-pressure control valve 10, so that a sufficient fuel injection pressure can be obtained, for example, during high-speed operation.

Next, a description will be given of a second embodiment. As shown in FIG.
Only the fuel pressure holding mechanism is different from that of the embodiment. That is, in this embodiment, a low-pressure control valve (low-pressure regulator) is used instead of the fixed throttle 15 as the fuel pressure holding mechanism.
17 are provided. The low pressure control valve 17 has a set pressure slightly lower than that of the low pressure control valve 9, and is closed until the fuel pressure exceeds a set pressure (for example, a pressure slightly smaller than 3 atm). When the set pressure is exceeded,
The fuel corresponding to the excess pressure is returned to the fuel tank 2 side.

The first bypass passage 11 and its check valve 12 and the second bypass passage 13 and its electromagnetic switching valve 14 are constructed in the same manner as in the first embodiment. With such a configuration, in the fuel supply device for an internal combustion engine according to the second embodiment, the low-pressure fuel pump 4 is operated at the same time as the engine is started, and the output pressure state is immediately brought to the predetermined pressure (several atmospheric pressures). Thus, even if the high-pressure fuel pump 5 does not reach a sufficient discharge pressure, the check valve 12 is opened and the fuel is supplied through the first bypass passage 11, and the low-pressure control valve 9 is supplied from the fuel injection valve 1.
The fuel injection is performed at a fuel pressure approximately equal to the pressure adjusted by the above.

At this time, the second bypass passage 1
3 is opened and the fuel pressure of the portion of the fuel injection valve 1 becomes approximately equal to the set pressure of the low pressure control valve 9, so that the low pressure control valve 17 provided downstream of the fuel injection valve 1 , A fuel pressure exceeding the set pressure (a pressure slightly smaller than 3 atm) is applied. As a result, the fuel on the side of the fuel injection valve 1 in the fuel passage 3 is discharged to the outside through the second bypass passage 13, and the vapor in the fuel is also discharged.

Of course, even when the second bypass passage 13 is open, the low pressure control valve 17 as the fuel pressure holding mechanism controls the fuel pressure near the fuel injection valve 1 by the low pressure control valve 9. Therefore, the fuel injection pressure from the fuel injection valve 1 is ensured at the time of starting the engine while discharging the vapor.

Although the fuel pressure is about the adjustment pressure level of the low-pressure control valve 9, the fuel pressure is stable, so that the rotation of the engine can be smoothly increased. Also increases smoothly. When the high-pressure fuel pump 5 starts operating to some extent, the check valve 12 closes the first bypass passage 11, and the discharge pressure of the high-pressure fuel pump 5 is adjusted without any loss of the high-pressure control valve 10. The fuel pressure becomes higher than the pressure.

In this process, as in the first embodiment, the solenoid-operated directional control valve 14 operates after a predetermined period of time has elapsed since the engine was started (ie, when the vapor was sufficiently discharged).
Since the valve is closed, the fuel pressure can be increased to the pressure controlled by the high-pressure control valve 10 thereafter, and the discharge pressure of the high-pressure fuel pump 5 is increased without hindrance. The injection pressure can be obtained.

In this manner, by securing the fuel pressure at the initial stage of the start-up through the first bypass passage 11 and discharging the vapor through the second bypass passage 13, the engine rotation speed is smoothly maintained while maintaining good engine combustion. And, for example, the practicality of a direct injection engine can be greatly improved. Next, the third
To explain the embodiment, this internal combustion engine fuel supply device is different from the first and second embodiments as shown in FIG.
The second bypass passage 13, the electromagnetic switching valve 14 provided in the passage 13, and the second low-pressure fuel pressure holding mechanisms 15, 17
Are omitted, and the other parts are configured in the same manner as in the first and second embodiments. Of course, the first bypass passage 11 and the check valve 12 provided therein are configured in the same manner as in the first and second embodiments.

With such a configuration, in the fuel supply system for an internal combustion engine according to the third embodiment, the low-pressure fuel pump 4 is activated at the same time as the engine is started, as in the first and second embodiments. Even if the high pressure fuel pump 5 is hardly operating, the check valve 12 is opened and the fuel is supplied through the first bypass passage 11, and the fuel injection valve 1 outputs the low pressure fuel. Fuel injection is performed at a fuel pressure about the pressure adjusted by the control valve 9.

Although the fuel pressure is about the same as the adjustment pressure level of the low pressure control valve 9, the fuel pressure is stable, so that the rotation of the engine can be smoothly increased. Also increases smoothly. When the high-pressure fuel pump 5 starts operating to some extent, the check valve 12 closes the first bypass passage 11, and the discharge pressure of the high-pressure fuel pump 5 is adjusted without any loss of the high-pressure control valve 10. Since the fuel pressure is increased above the pressure, the same effect as in the first and second embodiments can be obtained.

[0047]

As described above in detail, according to the fuel supply apparatus for an internal combustion engine of the present invention, the fuel injection valve in the internal combustion engine is provided so that the fuel in the fuel tank can be supplied. A low-pressure fuel pump provided in an upstream portion of the fuel passage; a high-pressure fuel pump provided between the low-pressure fuel pump and the fuel injection valve in the fuel passage; With a configuration in which a bypass passage connecting the upstream fuel passage and the downstream fuel passage is provided, and a check valve provided in the bypass passage and passing fuel only from the upstream side to the downstream side of the fuel passage is provided. ,
When the check valve opens and the low-pressure fuel pump operates, even if the high-pressure fuel pump is hardly operating, the fuel pressurized to a low pressure state is supplied through the bypass passage, and the stable fuel is supplied from the fuel injection valve. The fuel can be injected with the pressure, and the rotation speed of the engine can be smoothly increased while stably burning the engine.

When the high-pressure fuel pump starts operating,
The check valve closes the bypass passage, and the discharge pressure of the high-pressure fuel pump is sent to the fuel injection valve without loss, so that the fuel can be injected at a high fuel pressure. Further, according to the fuel supply device for an internal combustion engine of the present invention described in claim 2, in the configuration according to claim 1, the fuel passage portion downstream of the low-pressure fuel pump and upstream of the high-pressure fuel pump has Low-pressure control means for controlling the pressure of the fuel discharged from the low-pressure fuel pump is provided, and high-pressure control means for controlling the fuel pressure discharged from the high-pressure fuel pump is provided in a fuel passage downstream of the high-pressure fuel pump. With this configuration, the fuel pressure is stabilized, and the above-described stable combustion of the engine can be further ensured.

[Brief description of the drawings]

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

FIG. 2 is a graph showing output characteristics of a fuel pump of a fuel supply device for an internal combustion engine as a first embodiment of the present invention.

FIG. 3 is a schematic configuration diagram showing a fuel supply device for an internal combustion engine as a second embodiment of the present invention.

FIG. 4 is a schematic configuration diagram showing a fuel supply device for an internal combustion engine as a third embodiment of the present invention.

FIG. 5 is a schematic configuration diagram showing a conventional fuel supply device for an internal combustion engine.

FIG. 6 is a configuration diagram schematically showing a conventional fuel supply device for an internal combustion engine in relation to a main engine.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 fuel injection valve 2 fuel tank 3 fuel passage 3 A supply path 3 B return path 4 low pressure fuel pump 5 high pressure fuel pump 6 fuel filter 7 fuel filter 8 check valve 9 low pressure control valve (low pressure regulator) as low pressure control means 10 high pressure High pressure control valve (high pressure regulator) as control means 11 First bypass passage 12 Check valve 13 Second bypass passage 14 Electromagnetic switching valve 15 Fixed throttle as fuel pressure holding mechanism 16 Ignition key switch 17 Low pressure as fuel pressure holding mechanism Control valve (low pressure regulator)

──────────────────────────────────────────────────続 き Continued on the front page (72) Nobuaki Murakami, Inventor 5-33-8 Shiba, Minato-ku, Tokyo Inside Mitsubishi Motors Corporation (72) Inventor Hideyuki Oda 5-33-8, Shiba, Minato-ku, Tokyo Mitsubishi Motors Corporation (56) References JP-A-62-237059 (JP, A) JP-A-1-163427 (JP, A) JP-A-5-1854 (JP, U) JP-A-3-2 73667 (JP, U) JP-A 63-196471 (JP, U) JP-A 4-107474 (JP, U) JP-A 3-32170 (JP, U) (58) Fields surveyed (Int. Cl. ⁶ , DB name) F02M 37/00

Claims (2)

(57) [Claims] 1. A fuel passage provided between a fuel injection valve and a fuel tank in an internal combustion engine, a low pressure fuel pump provided in an upstream portion of the fuel passage, the low pressure fuel pump in the fuel passage, A high-pressure fuel pump provided between the fuel injection valve and a high-pressure fuel pump; a bypass passage connecting an upstream fuel passage portion and a downstream fuel passage portion of the high-pressure fuel pump is provided; A fuel supply device for an internal combustion engine, further comprising a check valve for passing fuel only from an upstream side to a downstream side of the fuel passage. 2. A low-pressure control means for controlling a fuel pressure discharged from the low-pressure fuel pump is provided in a fuel passage portion on the downstream side of the low-pressure fuel pump and on the upstream side of the high-pressure fuel pump. 2. The fuel supply device for an internal combustion engine according to claim 1, wherein a high pressure control means for controlling a fuel pressure discharged from the high pressure fuel pump is provided in a fuel passage portion downstream of the pump.