JP2845099B2 - 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. 6 and 7 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. 6 and 7, 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, and a supply path 3A for supplying fuel to the fuel injection valve 1; And a return path 3B. 4 is the fuel passage 3
The low-pressure fuel pump 5 and the high-pressure fuel pump 5 are provided between the low-pressure fuel pump and the fuel injection valve 1 in the upstream portion of the fuel tank 2. Reference numerals 6 and 7 denote fuel filters provided at the inlet of the fuel passage, 8 denotes a check valve, 9 denotes a low pressure control valve as low pressure fuel pressure control means (low pressure control means), and 10 denotes high pressure fuel pressure control means (high pressure control). Means) as a high-pressure control valve. 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 a certain degree 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 by further increasing the 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.

As such a technique, for example, Japanese Unexamined Patent Publication No. Sho 62
No. 2,370,57.

[0007]

By the way, in an internal combustion engine for an automobile, for example, after the engine stops, the temperature rise in the engine room caused by the stop of the engine cooling system, the pressure control valves 9, 10 and the fuel injection valve 1 , Vapor (bubbles) is likely to be generated in the fuel passage 3. Therefore, the next time the engine is to be started, the fuel supply is started with the vapor contained in the fuel passage 3.

In the case of a conventional multipoint injection (MPI) or the like, the fuel pressure supplied to the fuel injection valve 1 is not very high, and the pressure control valve downstream of the fuel injection valve 1 (the pressure control valve of the fuel supply device) The fuel pressure in the fuel passage 3 on the side of the fuel injection valve 1 is reduced in a short period of time by the pressure control valve. And the vapor in the fuel is also discharged.

However, as described above, if the fuel pressure supplied to the fuel injection valve 1 is significantly higher than in the case of the conventional multipoint injection (MPI), the set pressure of the pressure control valve 10 becomes higher. Until the fuel pressure reaches this set pressure, the fuel in the fuel passage 3 on the side of the fuel injection valve 1 does not flow out of the pressure control valve in a short time and is not injected. Therefore, the vapor in the fuel also stays on the side of the fuel injection valve 1 and is not easily discharged.

In general, it can be said that any pump takes a long time until the fuel pressure reaches a high set pressure. However, in the fuel supply apparatus having the above-described structure, it takes a long time. Due to the following configuration, it takes time for the fuel pressure to reach a high pressure. In other words, it is conceivable to employ either an engine-driven pump or an electric pump as the fuel pumps 4 and 5 as described above. However, if an electric pump is used as a high-pressure pump, the pump efficiency is reduced and Because of the high cost, it is generally considered that an engine-driven fuel pump is used as 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. The pressure becomes extremely low, and the fuel pressure does not rise easily. The vapor in the fuel is not easily discharged to the outside on the fuel injection valve 1 side. Such a fuel injection valve 1
Is undesirable because it causes delays and variations in the rise of the fuel pressure to be injected, or causes idle injection from the fuel injection valve 1, and makes it difficult to control the fuel injection.

If the vapor in the fuel is widely regarded as discharging the fuel, as a related technique, for example, Japanese Utility Model Laid-Open No. 4-107474 discloses a means for providing an air vent hole in a fuel passage immediately downstream of a fuel filter. ing.
In addition, for example, in Japanese Utility Model Laid-Open No. 2-145657, in addition to the fuel pump for fuel injection, a fuel pump for bleeding air is provided in series with the fuel pump, and a fuel bypass path bypassing the fuel pump for fuel injection is provided. There is disclosed a means for providing a check valve in this bypass path, which permits flow only in the direction from the fuel injection valve side to the air bleeding fuel pump.

However, none of these means is directed to a fuel supply device having a high fuel pressure such that a high-pressure control valve is provided downstream of the fuel injection valve. It is difficult to discharge the vapor inside. The present invention has been made in view of the above-described problems, and provides a fuel supply device for an internal combustion engine that can quickly discharge vapor contained in fuel near a fuel injection valve when the internal combustion engine is started. The purpose is to:

[0014]

According to a first aspect of the present invention, there is provided a fuel supply device for an internal combustion engine according to the first aspect of the present invention, wherein the fuel pumped from a fuel tank by a fuel pump is passed through a first fuel pressure control means again. a fuel passage for returning to the tank, fuel <br/> pressure control end to the fuel passage at the branching portion provided in the fuel passage communicating with said first between the fuel pump and said first fuel pressure control means a branch passage leading to the fuel tank, bypassing the means, and on-off valve interposed in the branch passage, the fuel passage between the fuel pump and said first fuel pressure control means, and, branching portion Prefecture A fuel injection valve for an internal combustion engine disposed in one of a branch passage between the valve and the on-off valve; and a fuel injection valve interposed in the branch passage.
Controlling the pressure of the fuel passage when the on-off valve is opened to the first fuel pressure control
Means to control the pressure to be lower than the pressure and higher than the atmospheric pressure
A fuel pressure control means for opening the on-off valve when the internal combustion engine is started.

According to a second aspect of the present invention, in the fuel supply device for an internal combustion engine according to the first aspect, the fuel injection valve is provided in a fuel passage between the fuel pump and the branch portion. It is characterized by being al. Claim 3
In the fuel supply device for an internal combustion engine according to the present invention, the fuel injection valve is provided in a branch passage between the branch portion and the on-off valve, and the second fuel pressure control is performed. means
But it is characterized by being kicked set downstream of the fuel injection valve in said branch passage.

According to a fourth aspect of the present invention, there is provided a fuel supply device for an internal combustion engine according to any one of the first to third aspects, wherein the second fuel pressure control means is provided for the internal combustion engine. The fuel injection valve is set to control the fuel pressure to a desired pressure at the time of starting.

[0017]

In the fuel supply device for an internal combustion engine according to the first aspect of the present invention, the opening and closing of the on-off valve disposed in the branch passage is controlled by the on-off valve control means. When the open / close valve is closed, when the fuel pump operates, the fuel in the fuel tank returns to the fuel tank again while flowing through the fuel passage without bypassing the first fuel pressure control means. , And during this time, it is pumped to the fuel injection valve. At this time, the fuel pressure injected by the fuel injection valve is equal to the first pressure .
Is controlled while the flow is regulated by the fuel pressure control means.

On the other hand, when the on-off valve is open,
When the fuel pump is activated, the fuel in the fuel tank, the first
By returning to the fuel tank while bypassing the fuel pressure control means and flowing through the branch passage, the fuel is fed to the fuel injection valve during this time. Since at this time does not pass the first fuel pressure control means, the fuel in the vicinity of the fuel injection valve is not to be restricted flows in the first <br/> fuel pressure control means, the branch passage
The pressure is increased to the first pressure by the second fuel pressure control means interposed in the road.
Controlled at a pressure lower than the fuel pressure control means and above atmospheric pressure
The fuel injection valve
Fuel injection from the engine is now performed at a stable injection pressure.
You.

[0019] In an internal combustion engine fuel supply device of the present invention of the above second aspect, by the opening and closing valve control means, when the closing valve is opened, the fuel pump, the fuel in the fuel tank, a first fuel pressure By returning to the inside of the fuel tank while bypassing the control means and flowing through the branch passage, the fuel is pumped to the fuel injection valve between the fuel pump and the branch portion. At this time, the fuel pressure to be injected by the fuel injection valve is controlled to a lower pressure than the first fuel pressure control means by the second fuel pressure control means. Therefore, the fuel in the vicinity of the fuel injection valve, the
It becomes easier to flow to the downstream side than when regulated by the first fuel pressure control means.

In the fuel supply device for an internal combustion engine according to the third aspect of the present invention, when the on-off valve is opened by the on-off valve control means, the fuel in the fuel tank is supplied from the fuel pump to the first fuel pressure. By returning to the inside of the fuel tank while bypassing the control means and flowing through the branch passage, the fuel is fed to the fuel injection valve between the branch portion and the on-off valve during this time. At this time, the fuel pressure to be injected by the fuel injection valve is controlled to a lower pressure than the first fuel pressure control means by the second fuel pressure control means. Therefore, the fuel in the vicinity of the fuel injection valve, the
It becomes easier to flow to the downstream side than when regulated by the first fuel pressure control means.

In the fuel supply device for an internal combustion engine according to the present invention, when the on-off valve is opened, the fuel in the fuel tank bypasses the first fuel pressure control means by the fuel pump. The fuel is returned to the inside of the fuel tank while flowing through the branch passage, and during this time, the fuel is fed to the fuel injection valve between the branch portion and the on-off valve. At this time, the fuel pressure injected by the fuel injection valve is determined by the second fuel pressure control means.
The fuel injection valve is controlled at a lower pressure than the first fuel pressure control means and at a desired pressure when the internal combustion engine is started.

[0022]

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, and FIG. 5 is a schematic diagram showing a fuel supply device for an internal combustion engine as a fourth embodiment of the present invention. FIG.

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 part 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. In the middle of a feed path 3A from the low-pressure fuel pump 4 to the high-pressure fuel pump 5, 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 pressure of the fuel pumps 4 and 5 is determined by such discharge flow characteristics and the low pressure control valve 9 as low pressure fuel pressure control means (low pressure control means) and the first fuel pressure control means (high pressure control means) described later. Since it is determined by the flow resistance of the high-pressure control valve 10 and the like, the discharge flow rate characteristic in this case cannot be read as the discharge pressure characteristic as it is, but the discharge pressure characteristic is almost equivalent to the discharge flow rate characteristic. Become. 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.

Further, the feed path 3A of the fuel passage 3 and the return path 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 (low pressure regulator) 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 (high-pressure regulator) 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
As a branch passage connecting the upstream part and the downstream part 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. Passage (hereinafter, referred to as a first bypass passage) 1
1 is provided. Also, 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. This check valve 12
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 first bypass passage 11 is opened and the high pressure fuel pump 5
Operates sufficiently and the fuel pressure on the downstream side of the high pressure fuel pump 5 becomes higher than that on the upstream side, so that the first bypass passage 11
Is to be closed.

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) 1 as a branch passage connecting the upstream side portion and the downstream side portion of the “0”.
3 are 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, the second bypass passage 13 is provided with an electromagnetic switching valve 14 as an on- off valve for opening and closing the second bypass passage 13,
A second fuel pressure control means (hereinafter, referred to as a fuel pressure holding mechanism) 15 capable of maintaining the fuel pressure at the upstream side of the bypass passage 13, that is, at the fuel injection valve 1 portion, at a predetermined pressure is provided. In addition, in the figure, 13A is a branch part.

The solenoid-operated switching valve 14 opens the second bypass passage 13 when operated with electric power, and closes the second bypass passage 13 when stopped with the electric power cut 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, on / off valve control means 30 for controlling the opening / closing of the electromagnetic switching valve 14 is provided. A mechanism that attaches an operating timer and stops the electromagnetic switching valve 14 when the set time has elapsed can be used. Further, for example, when the power supplied to the electromagnetic switching valve 14 is electronically controlled by a controller, the controller can be used as the on-off valve control means 30. That is, power is supplied to the electromagnetic switching valve 14 based on the starter-on signal from the ignition key switch 16 through the controller, and the attached timer is started. The power supply to the valve 14 may be stopped.

It is generally assumed that the time for the above-described vapor discharge operation, that is, the time for opening the electromagnetic switching valve 14, is sufficient for a short engine (within several seconds) after the engine is started. Immediately after the start of the engine, even if the second bypass passage 13 is opened, the fuel pressure holding mechanism 15 has a fuel pressure at least close to the set pressure (for example, 3 atm) controlled by the low-pressure control valve 9, that is, 1 as fuel pressure control means
Pressure lower than the pressure controlled by the high pressure control valve 10
Over the fuel pressure ,
In this embodiment, as the fuel pressure holding mechanism 15, a so-called fixed throttle that only narrows the inner diameter of the fuel passage 3 is provided.

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 is started. (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 start of the engine, 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 configured such that if 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 is 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. Also, 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 near the fuel injection valve 1 flows through the return passage 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 adjusts the fuel pressure near the fuel injection valve 1 at least to the set pressure controlled by the low pressure control valve 9. , The fuel injection pressure from the fuel injection valve 1 is sufficient when the engine is started, that is, while discharging the vapor ,
Only a pressure somewhat higher than atmospheric pressure is ensured.

Accordingly, it is possible to obtain a certain fuel injection pressure while preventing a phenomenon such as a delay or variation in the rise of the fuel pressure caused by the vapor immediately after the start of the engine or a phenomenon such as idle injection. 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.

Further, 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 is started and the vapor is 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.

As shown by a two-dot chain line in FIG. 1, a fuel pressure sensor 18 for detecting the fuel pressure for the fuel injection valve 1 is provided immediately downstream of the fuel injection valve 1. It is also conceivable to detect a failure in the fuel supply system based on the detection information and warn the driver of the failure or to feed it back to the fuel supply control. in this case,
For example, if the fuel pressure detected by the fuel pressure sensor 18 becomes lower than the set pressure range, it is estimated that the fuel is leaking due to, for example, damage to the fuel injection valve 1, the seal portion or the piping of the pump system, or the like. it can. When the fuel pressure detected by the fuel pressure sensor 18 becomes higher than the set pressure range, it can be inferred that valves on the return path 3B such as the high-pressure control valve 10 and the electromagnetic switching valve 14 are locked.

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 17 is provided as a fuel pressure holding mechanism instead of the fixed throttle 15. 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 pressure exceeds the set pressure, 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, as described above, the second bypass passage 13
Is open, the low pressure control valve 17 as a fuel pressure holding mechanism reliably holds the fuel pressure near the fuel injection valve 1 to a level close to the set pressure controlled by the low pressure control valve 9. And the fuel injection pressure from the fuel injection valve 1 is secured to a sufficient degree at the time of engine start. 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, and the discharge pressure of the high pressure fuel pump 5 increases with the rotation of the engine. Also rises smoothly.

When the high-pressure fuel pump 5 starts operating to some extent, the check valve 12 closes the first bypass passage 11, so that the discharge pressure of the high-pressure fuel pump 5 is maintained without loss. The fuel pressure will be increased to more than 10 adjustment pressures. Also, in this process, as in the first embodiment, the electromagnetic switching valve 14 closes after a lapse of a predetermined period of time after the engine is started (that is, when the vapor is sufficiently discharged). The fuel pressure can be increased to the pressure controlled by the control valve 10, and the increase in the discharge pressure of the high-pressure fuel pump 5 is performed without hindrance, so that a sufficient fuel injection pressure can be obtained during high-speed operation or the like.

In this manner, by securing the fuel pressure at the initial stage of the start through the first bypass passage 11 and discharging the vapor through the second bypass passage 13, the engine speed can be 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 such that an accumulator 19 and a check valve 20 are added to the second embodiment as shown in FIG.

That is, the fuel passage 3 in the portion of the fuel injection valve 1
, An accumulator 19 is provided, and the high-pressure fuel pump 5 is provided with a check valve 20. This check valve 20 may be provided in series with the high-pressure fuel pump 5 at an inlet portion upstream of the high-pressure fuel pump 5 as shown in the drawing, or provided in series with the high-pressure fuel pump 5 at an outlet portion downstream of the high-pressure fuel pump 5. You may.

Such an accumulator 19 and the check valve 2
0 is for keeping the fuel pressure in the fuel passage 3 near the fuel injection valve 1 constant even when the temperature of the engine decreases from high temperature to normal temperature after the engine stops. This is to prevent vapor (bubbles) from entering the fuel passage 3 at the fuel injection valve 1 from the outside even if fuel leaks when the engine is cold.

With such a configuration, in the fuel supply device 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.

In general, after the engine is stopped, the fuel pressure decreases due to a rise in the temperature in the engine room and a fuel leak in the pressure control valves 9 and 10 and the fuel injection valve 1, but the fuel pressure is sufficiently accumulated in the accumulator 19. The leaked fuel replenishes the leaked amount, so that a decrease in fuel pressure is suppressed. At this time, the fuel in the portion of the fuel injection valve 1 is prevented from leaking by the check valve 20 on the upstream side, and is prevented by the high-pressure control valve 10 on the downstream side. Of course, when the engine is stopped, the electromagnetic switching valve 14 is closed to prevent leakage here.

As a result, it becomes difficult for the vapor to enter the fuel passage 3 in the portion of the fuel injection valve 1 after the engine is stopped.
In addition, when vapor is generated in the vicinity of the fuel injection valve 1 also by such an operation, in the present device, the second bypass passage 13 parallel to the high-pressure control valve 10 is opened for a predetermined period after the engine is started. Therefore, the fuel flows through the second bypass passage 13 to the downstream side of the return passage 3B while bypassing the high-pressure control valve 10, and together with the fuel flow, the vapor contained in the vicinity of the fuel injection valve 1 in the fuel passage 3 Is discharged outside the fuel passage 3.

In this configuration, since vapor is unlikely to be generated from the beginning, even if vapor is generated, it is slight, and the vapor is discharged very quickly after the engine is started. Therefore, the opening time of the second bypass passage 13 can be set extremely short, and the closing of the second bypass passage 13 allows the fuel pressure to be increased quickly. As described above, even when the second bypass passage 13 is open, the fuel pressure holding mechanism 15 holds the fuel pressure. Therefore, the fuel injection pressure from the fuel injection valve 1 is maintained while discharging the vapor. Only enough when starting the engine is secured.

As described above, in the present embodiment, the above-mentioned first and second
The fuel pressure can be increased more quickly than in the case of the second embodiment, and the practicality of, for example, an in-cylinder injection type engine can be greatly improved. Next, a description will be given of a fourth embodiment. This fuel supply device for an internal combustion engine is different from that of the first embodiment in the arrangement of the fuel injection valve 1 as shown in FIG. That is, in this embodiment, the fuel injection valve 1
The fuel pressure sensor 18 is provided in the middle of the bypass passage 13 on the downstream side of the branch portion 13A, and accordingly, the fuel pressure sensor 18 is also provided immediately downstream of the fuel injection valve 1.

With such a configuration, the fuel supply device for an internal combustion engine according to the fourth embodiment can obtain substantially the same operation and effects as those of the first embodiment. In the second and third embodiments, the fuel pressure sensor 18 may be provided to detect a failure as in the case described in the first embodiment. Further, in each of the above-described embodiments, when the engine is started, the high-pressure fuel pump is bypassed and the low-pressure fuel pump is used to feed the fuel to the fuel injection valve. However, the present invention is not limited to this. The present invention can be applied to a fuel supply device for an internal combustion engine in which a high-pressure fuel pump is not bypassed even at the time of engine start, as shown in Japanese Patent Application Laid-Open No. 62-237057.

[0062]

As described above in detail, according to the fuel supply system for an internal combustion engine according to the first aspect of the present invention, the fuel pumped from the fuel tank by the fuel pump is again passed through the first fuel pressure control means. a fuel passage for returning to the fuel tank, fuel pump and said first end communicates with the fuel passage at the branching portion provided in the fuel passage through said first <br/> fuel pressure between the fuel pressure control means a fuel passage between the branch passage leading to the fuel tank by bypassing the control unit, an opening and closing valve interposed in said branch passage, a fuel pump and said first fuel pressure control means, and, the branch portion A fuel injection valve for an internal combustion engine disposed in one of a branch passage between the fuel injection valve and the on- off valve;
When the on-off valve is opened, the pressure in the fuel passage is reduced by the first fuel pressure control.
Control to a pressure lower than the control means and above atmospheric pressure
With the configuration including the second fuel pressure control means and the on-off valve control means for opening the on-off valve when the internal combustion engine is started, the fuel pressure from the fuel pump does not reach the adjustment pressure of the first fuel pressure control means. Also in this case, by opening the on-off valve, the fuel near the fuel injection valve is discharged to the downstream side through the branch passage, so that the vapor (bubbles) in the fuel is easily discharged.

The discharge of the vapor eliminates delays and variations in the rise of the fuel pressure, or a problem that causes the fuel injection valve to cause idle injection, so that the fuel injection can be controlled appropriately. Also, when opening this on-off valve
The fuel pressure near the fuel injection valve is interposed in the branch passage.
The first fuel pressure control means by the second fuel pressure control means
Lower than atmospheric pressure and higher than atmospheric pressure
Fuel injection from the fuel injection valve with stable injection pressure
Will be performed. As a result, the fuel pressure rises
Rising delay or variation, or idle injection from fuel injector
This eliminates the inconvenience that could cause
To be able to perform quickly, and to stabilize combustion
Thus, the startability of the internal combustion engine is also ensured. Claim 2
According to the fuel supply apparatus for an internal combustion engine of the present invention described, in the structure according to claim 1, the configuration of the fuel injection valve, the fuel passage is provided et the between the fuel pump and the branch portion, Even when the fuel pressure from the fuel pump does not reach the adjustment pressure of the first fuel pressure control means, by opening the on-off valve, the fuel near the fuel injection valve is discharged to the downstream side through the branch passage. Become vapor (bubbles) in fuel
Is more easily discharged .

[0064]

According to a third aspect of the present invention, there is provided a fuel supply device for an internal combustion engine according to the first aspect of the invention.
Fuel injection valve is provided in the branch passage between the branch section and said opening and closing valve, the second fuel pressure control means, the configuration that eclipsed set downstream of the fuel injection valve in said branch passage Even when the fuel pressure from the fuel pump does not reach the adjustment pressure of the first fuel pressure control means, by opening the on-off valve, the fuel near the fuel injection valve is discharged to the downstream side through the branch passage. And the vapor (bubbles) in the fuel
It is easier to discharge .

[0066] Also, according to the internal combustion engine fuel supply device of the present invention described in claim 4, in the structure of any one of claim to <br/> of claims 1 to 3, the fuel pressure control of the second means, the pressure at the start of the internal combustion engine fuel injector desired, the configuration that is set to control the fuel pressure, for example at the start of the internal combustion engine, the fuel pressure from the fuel pump
By opening the on-off valve when the adjustment pressure of the first fuel pressure control means is not reached, fuel near the fuel injection valve is discharged to the downstream side through the branch passage. vapor in the fuel (air bubbles) is so that <br/> is discharged. At this time, the fuel flowing through the branch passage is subjected to the desired pressure control of the fuel injection valve at the start of the internal combustion engine through the second fuel pressure control means, so that the fuel from the fuel injection valve is stably injected at an appropriate pressure. You.

As a result, for example, when the internal combustion engine is started, delay or variation in the rise of the fuel pressure, or
The problem of causing idle injection from the fuel injection valve has been resolved,
Control of fuel injection can be appropriately performed, and combustion becomes stable from the start of the engine.

[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 fuel supply device for an internal combustion engine as a fourth embodiment of the present invention.

FIG. 6 is a schematic configuration diagram showing a conventional fuel supply device for an internal combustion engine.

FIG. 7 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 3A feed path 3B 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 as low pressure fuel pressure control means (low pressure control means) 10 High pressure control valve as first fuel pressure control means (high pressure control means) 11 First bypass passage (branch passage) 12 Check valve 13 Second bypass passage (branch passage) 13A Branch 14 Electromagnetic switching valve as on / off valve 15 Fixed throttle as second fuel pressure control means 16 Ignition key switch 17 Low pressure control valve as second fuel pressure control means 18 Fuel pressure sensor 19 Accumulator 20 Check valve 30 Open / close valve control means

──────────────────────────────────────────────────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 Inside Mitsubishi Motors Corporation (56) References JP-A-62-237057 (JP, A) JP-A-57-52668 (JP, A) Fully open Showa 62-122146 (JP, U) Really open 111558 (JP, U) JP-A 4-107474 (JP, U) JP-A 2-145657 (JP, U) JP-A 63-196471 (JP, U) (58) Field surveyed (Int. Cl. ⁶ , DB name) F02M 37/00 F02M 37/20

Claims (4)

(57) [Claims] Fuel between 1. A fuel passage back again fuel tank via a first fuel pressure control means pumping fuel from a fuel tank by a fuel pump, fuel pump and said first fuel pressure control means a branch passage leading to the fuel tank at one end to the fuel passage bypassing the first fuel pressure control means communicating with the branch portion provided in the passage opening and closing valve interposed in the branch passage, fuel a fuel passage between the pump and said first fuel pressure control means, and, the branch section and the branch passage, a fuel injection valve for an internal combustion engine arranged in one of between the on-off valve, the The fuel passage is interposed in the branch passage when the on-off valve is opened.
The pressure is lower than the first fuel pressure control means and the atmospheric pressure is lower.
A fuel supply device for an internal combustion engine, comprising: second fuel pressure control means for controlling the pressure to exceed the pressure; and on-off valve control means for opening the on-off valve when the internal combustion engine is started. 2. A fuel injection valve, characterized in that the fuel passage is provided et between the fuel pump and the branch portion, the fuel supply system for an internal combustion engine according to claim 1. 3. A fuel injection valve is provided in the branch passage between the branch section and said opening and closing valve, the second fuel pressure control means, set downstream of the fuel injection valve in said branch passage The fuel supply device for an internal combustion engine according to claim 1, wherein the fuel supply device is provided. 4. The fuel pressure control device according to claim 1, wherein said second fuel pressure control means is set to control said fuel pressure to a pressure desired by said fuel injection valve when said internal combustion engine is started. The fuel supply device for an internal combustion engine according to any one of claims 1 to 3.