JPH0925860A - Fuel supplying device for internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent an increase in a tank inner pressure by limiting the generation of evaporated fuel in a fuel tank and to reduce costs by simplifying the piping of a fuel supplying system in an internal combustion engine fuel supplying device. SOLUTION: A low pressure pump P1 is provided in a fuel passage 23 for interconnecting a fuel injection valve 1 and a fuel tank 22 and a high pressure pump P2 is provided between the low pressure pump P1 and the fuel injection valve 1. A high pressure regulator R2 is provided in parallel with the fuel injection valve 1 or in the downstream of the injection valve in order to adjust a fuel supplying pressure to the fuel injection valve 1 to a set pressure and a high pressure return passage r2 for returning a superfluous fuel passing through the high pressure regulator R2 to a fuel passage 23 between the high pressure pump P2 and the low pressure pump P1 is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel supply device in a system for supplying fuel from a fuel tank to an engine through a fuel injection valve, and more particularly to a cylinder injection type in which a fuel injection valve is provided in each cylinder of the engine. The present invention relates to a fuel supply device for an internal combustion engine, such as an engine, which requires a relatively high injection pressure.

[0002]

2. Description of the Related Art Generally, a fuel supply system of an engine pressurizes fuel in a fuel tank with a low pressure pump (feed pump) and supplies it to a fuel injection valve of each cylinder of an engine body through a fuel pipe and a delivery pipe. . Moreover, the surplus fuel that has not been consumed by this fuel injection valve is roughly configured to be returned to the fuel tank via the return path. By the way, the piping on the fuel injection valve side of the fuel supply system is likely to receive the heat of the engine body. In particular, when the ambient temperature of the engine is relatively high, the temperature of the fuel returning from the return path is likely to increase, and the amount of evaporated fuel increases.

In order to cope with this, the evaporated fuel generated in the fuel tank is adsorbed by an adsorbent such as activated carbon in the canister and liquefied to prevent a high pressure in the fuel tank, and
The fuel in the canister is sent to the intake system of the engine to perform the canister purging process.
There is known a cylinder injection gasoline engine in which gasoline fuel is directly injected into a cylinder by a fuel injection valve in order to improve responsiveness of fuel supply and controllability of combustion. The fuel supply system of this in-cylinder injection engine is disclosed in JP-A-7-7.
7120 and Japanese Patent Laid-Open No. 7-83134, the fuel supply system is basically constructed as shown in FIG. Here, the fuel in the fuel tank 1 is pressurized by the feed pump 2, guided to the high pressure pump 5 via the check valve 3 and the filter 4, and the low pressure regulator 6 stabilizes the fuel pressure of the feed pump 2. Further, the high-pressure pump 5 is driven by the rotation of the engine, supplies pressurized fuel to each fuel injection valve 9 through the high-pressure pipe 7 and the delivery pipe 8, and increases the pressure of fuel by the fuel injection valve 9. Atomize into a cylinder and spray.

Here, the surplus fuel passing through the delivery pipe 8 is passed through the high pressure regulator 10 to be reduced in pressure,
It is returned to the fuel tank 1 via the low-pressure return path 11.
Reference numeral 12 indicates a high-pressure pump bypass passage provided with a check valve 15, and reference numeral 13 indicates a high-pressure regulator bypass passage provided with an opening / closing valve 14. In this case, the rise of the fuel pressure of the high-pressure pump 5 is delayed when the engine is started, but during that time, the relatively low-pressure fuel of the electric feed pump 2 is supplied to the delivery pipe 8 through the high-pressure pump bypass passage 12, and the surplus fuel is opened / closed by the open / close valve 14. It is returned to the return path 11 via the open high-pressure regulator bypass path 13 to ensure startability. During normal operation after startup, the high pressure regulator bypass passage 13 is closed, the fuel in the fuel tank 1 is sequentially pressurized by the feed pump 2 and the high pressure pump 5, and returned to the return passage 11 via the high pressure regulator 10.

As described above, in particular, in the fuel supply system of the direct injection engine, the fuel is pressurized by the high-pressure pump 5, so that the surplus fuel returning from the fuel injection valve 9 to the return path 11 is generated by the conventional intake port injection. As compared with the case where the pressure is increased, the temperature is likely to increase, and when the high temperature fuel returns to the fuel tank, a relatively large amount of evaporated fuel is generated, and in order to cope with this, it is necessary to dispose a relatively large canister.

[0006]

As described above, if the piping on the fuel injection valve side of the fuel supply system has a relatively high ambient temperature of the engine, it is easy to receive the heat of the engine body, especially in the case of a cylinder injection engine. In the fuel supply system, in addition to the ambient temperature of the engine, heat generated by high compression is also added, and the temperature of the fuel returning from the return path tends to become higher, and a relatively large amount of evaporated fuel tends to be generated. To deal with this, simply increasing the size of the canister has a limit in terms of layout and purging, and a more appropriate improvement for evaporation prevention is desired.

Further, a large number of pipes are connected to the high-pressure pump that is directly driven by the engine, which complicates the pipe structure around the high-pressure pump and tends to cause problems in layout workability improvement. , Improvement is desired. An object of the present invention is to provide a fuel supply device for an internal combustion engine, which can regulate the generation of evaporated fuel in a fuel tank and can simplify the piping of the fuel supply system.

[0008]

In order to achieve the above object, the invention of claim 1 is a low pressure pump interposed in a fuel passage connecting a fuel injection valve and a fuel tank, and the low pressure pump. A high-pressure pump provided between the fuel injection valve and a fuel pressure adjustment provided in parallel with the fuel injection valve or downstream of the injection valve so that the fuel pressure supplied to the fuel injection valve is adjusted to a set pressure. And a high pressure return passage for returning excess fuel passing through the fuel pressure adjusting means to a fuel passage between the high pressure pump and the low pressure pump.

According to a second aspect of the present invention, in the fuel supply system for an internal combustion engine according to the first aspect, the fuel passage between the high pressure return passage and the low pressure pump is connected to the fuel tank via the low pressure fuel adjusting means. It is characterized by having a low pressure return passage.

According to a third aspect of the present invention, in the fuel supply system for an internal combustion engine according to the second aspect, the upstream end of the low pressure return passage is located upstream of the downstream end of the high pressure return passage.

According to a fourth aspect of the invention, in the fuel supply system for an internal combustion engine according to the third aspect, the fuel passage length between the upstream end of the low pressure return passage and the downstream end of the high pressure return passage is the high pressure pump. And a fuel passage length between the low pressure pump and the downstream end of the high pressure return passage, and a fuel passage length between the low pressure pump and the low pressure return passage.

According to a fifth aspect of the present invention, in the fuel supply system for an internal combustion engine according to the first aspect, the fuel pressure adjusting means is connected to the downstream side of the fuel injection valve, branches from the return passage, and the downstream side is on the fuel tank side. And a switching valve means for switching so as to guide the surplus fuel to either the downstream end of the return passage or the second return passage.

According to a sixth aspect of the present invention, in the fuel supply system for an internal combustion engine according to the fifth aspect, the switching valve means is
A control means for switching the surplus fuel to the upstream of the high-pressure pump in the normal operation state of the internal combustion engine and to the second return passage in the specific operation state is provided.

According to a seventh aspect of the invention, in the fuel supply system for an internal combustion engine according to the fifth aspect, a bypass passage connecting the upstream side and the downstream side fuel passage portion of the fuel pressure adjusting means is arranged, An on-off valve for opening and closing the bypass passage is provided.

According to an eighth aspect of the invention, in the fuel supply system for an internal combustion engine according to the seventh aspect, the opening / closing valve is controlled to be opened / closed in a normal operation state of the internal combustion engine and opened / closed in a specific operation state. It is characterized by including.

The invention of claim 9 is claim 6 or claim 8.
In the fuel supply device for an internal combustion engine as described above, the specific operation state is a state in which the discharge pressure of the high-pressure pump is not sufficient.

According to a tenth aspect of the present invention, in the fuel supply system for an internal combustion engine according to the ninth aspect, the high pressure pump is driven by the internal combustion engine, and the specific operation state is when the internal combustion engine is started. To do.

According to a tenth aspect of the present invention, in the fuel supply system for an internal combustion engine according to the first aspect, the second bypass passage connecting the upstream and downstream fuel passages of the high pressure pump so as not to pass through the fuel pressure adjusting means. It is characterized by being arranged.

According to a twelfth aspect of the present invention, in the fuel supply system for an internal combustion engine according to the eleventh aspect, an opening / closing valve is arranged in the second bypass passage.

A thirteenth aspect of the invention is the fuel supply system for an internal combustion engine according to the twelfth aspect, wherein the opening / closing valve is controlled so as to be closed in the normal operation state of the internal combustion engine and opened in the specific operation state. It is characterized by including.

According to a fourteenth aspect of the present invention, in the fuel supply system for an internal combustion engine according to the thirteenth aspect, the specific operation state is:
It is characterized in that the discharge pressure of the high-pressure pump is not sufficient.

According to a fifteenth aspect of the present invention, in the fuel supply system for an internal combustion engine according to the fourteenth aspect, the high pressure pump is driven by the internal combustion engine, and the specific operation state is when the internal combustion engine is started. .

According to a sixteenth aspect of the present invention, in the fuel supply system for an internal combustion engine according to the eleventh aspect, a check valve is arranged in the second bypass passage.

According to a seventeenth aspect of the present invention, in the fuel supply system for an internal combustion engine according to the twelfth or sixteenth aspect, a low pressure return passage for returning the upstream fuel from the high pressure pump to the fuel tank via the low pressure regulator is provided. It is characterized by having done.

According to a eighteenth aspect of the present invention, in the fuel supply system for an internal combustion engine according to the seventeenth aspect, the upstream side of the low pressure passage is located downstream of the high pressure return passage and upstream of the upstream end of the second bypass passage. It is characterized by doing.

According to a nineteenth aspect of the present invention, in the fuel supply system for an internal combustion engine according to the eighteenth aspect, the upstream side of the low pressure passage is provided close to the low pressure pump, and the downstream end of the high pressure return passage and the second bypass. The upstream end of the passage is characterized in that it is provided close to the high-pressure pump.

According to a twentieth aspect of the present invention, there is provided a fuel injection valve which opens when the fuel pressure exceeds a predetermined value, a low pressure pump interposed in a fuel passage connecting the fuel injection valve and a fuel tank, and the low pressure pump. And a high-pressure pump provided between the fuel injection valve, and a high-pressure return passage for returning excess fuel passing through the fuel injection valve to a fuel passage between the high-pressure pump and the low-pressure pump. Characterize.

[0028]

1 shows a fuel supply system 20a for a cylinder injection engine as a first embodiment of the present invention. The fuel supply device 20a for the in-cylinder injection engine is attached to a fuel supply system of a four-cylinder DOHC gasoline engine (hereinafter simply referred to as engine) 21 shown in FIGS. 9 and 10, and includes a fuel injection valve I and a fuel tank 22. The low-pressure pump P1 interposed in the fuel passage 23 to be connected, the high-pressure pump P2 provided between the low-pressure pump P1 and the fuel injection valve I, and the fuel pressure supplied to the fuel injection valve I are adjusted to the set pressure. Therefore, the high-pressure regulator R2 as fuel pressure adjusting means provided in parallel with the fuel injection valve I, and the excess fuel passing through the high-pressure regulator R2 are supplied to the fuel passage 2 between the high-pressure pump P2 and the low-pressure pump P1.
And a high-pressure return passage r2 for returning to 3.

Here, as shown in FIG. 10, the engine 21 is installed laterally in an engine room 24 in the front part of the vehicle C, and the engine 21 and the front wheels 26 as driving wheels are connected by a power transmission system 25. Has been done. A fuel tank 22 is attached to the rear portion of the vehicle C, and a low pressure pump P1 as an electric feed pump is attached to the inside of the tank. The fuel in the fuel tank 22 is shown in FIG. 1 when the low pressure pump P1 is driven. Check valve 27, filter 28
And is discharged to the fuel passage 23 through. A relatively small canister (not shown) is attached to the fuel tank 22 so as to adsorb a relatively small amount of evaporated fuel and perform a purge operation at a proper time.

As shown in FIG. 9, the engine 21 is provided with a cylinder block 30 in which a piston 29 is fitted and inserted, and a cylinder head 31 is provided above the cylinder block 30.
And the head cover 32 are superposed in this order and integrally coupled. The cylinder head 31 has intake and exhaust ports 35 and 36 that are opened and closed by intake and exhaust valves 33 and 34,
In particular, the intake port 35 is formed to be long in the vertical direction, and a fuel injection valve I is attached to the side end of the intake port 35, and the fuel injection valve I enables direct fuel injection into the combustion chamber 37. The fuel injection valve I is provided for each cylinder (see the broken line in FIG. 10), and each fuel injection valve I is longer than the delivery pipe 38 which is long in the engine longitudinal direction (vehicle width direction) and integrally attached to the cylinder head 31. High-pressure fuel supplied, engine control unit (hereinafter simply referred to as ECU) 3
The valve opening operation is performed according to the drive signal from 9a, and the high-pressure fuel can be atomized and atomized.

The delivery pipe 38 of the fuel supply system for the direct injection engine shown in FIG. 1 is connected to the high pressure passage 40 for receiving the discharge pressure of the high pressure pump P2 as shown by the solid line, and the high pressure fuel is always supplied during the steady operation of the engine. Is being supplied. The high-pressure passage 40 includes a high-pressure pump P2 and a delivery pipe 3
It communicates with 8. The high-pressure pump P2 is directly driven by an unillustrated exhaust camshaft on the engine body side, receives the low-pressure fuel from the low-pressure pump P1 through the fuel passage 23, increases the pressure, and discharges it to the high-pressure passage 40 side.

Here, a part of the high pressure passage 40 is branched, and a high pressure regulator R2 as a fuel pressure adjusting means provided in parallel with the fuel injection valve I and a high pressure return passage r2 are connected thereto. The downstream end of the high pressure return passage r2 communicates with the fuel passage 23 on the upstream side of the high pressure pump P2.
The high-pressure regulator R2 takes in the fuel pressure (fuel pressure) of the high-pressure passage 40 at the pilot port a, and responds to the balance pressure operation of the plunger (not shown) that receives the fuel pressure and the urging force of the compression spring (not shown) from the opposite direction. Is adjusted to a predetermined value, and excess fuel passing through the high pressure regulator R2 is returned to the low pressure side fuel passage 23.

Here, the filter 28 on the fuel tank 22 side
10, the fuel passage 23 between the suction position c on the suction port side of the high-pressure pump P2 is equal to or longer than the length of the vehicle interior 41 of the vehicle C as shown in FIG. It is formed of pipe-shaped piping. On the other hand, the suction port position d (see FIG. 1) on the fuel tank 22 side and the filter 2
The length between 8 and the discharge side position b, or the length between the suction position c and the delivery pipe 38 is shorter than that of the fuel passage 23.

In the engine 21 equipped with the fuel supply device 20a for the in-cylinder injection engine of FIG. 1, the electric low-pressure pump P1 first discharges the low-pressure fuel to the fuel passage 23 with good response. The low-pressure fuel that has reached the fuel passage 23 is increased in pressure by the high-pressure pump P2 performing a predetermined pressurization operation, and the fuel discharged from the high-pressure pump P2 passes through the high-pressure passage 40 and each fuel injection valve on the delivery pipe 38 side. Supplied to I,
When each fuel injection valve I receives the drive pulse of the ECU 39, it opens to execute in-cylinder injection of gasoline, and the engine 2
The output torque is generated at 1. At this time, the fuel pressure in the delivery pipe 38 and the high-pressure passage 40 is adjusted to a predetermined pressure by the high-pressure regulator R2, and the surplus fuel generated according to the engine speed passes through the high-pressure regulator R2 and reaches the downstream end of the high-pressure return passage r2. It is returned to the suction position c of a certain fuel passage 23.

As described above, the high-pressure fuel pressurized by the high-pressure pump P2 and having a high temperature passes through the high-pressure regulator R2 and reaches the suction position c of the high-pressure return passage r2, not on the fuel tank 22 side, and then enters the high-pressure pump P2 again. It is sucked, supplied to the fuel injection valve I on the high pressure passage 40 side, and consumed. Therefore, since the high-pressure fuel whose temperature has risen is not returned to the fuel tank 22, the problem that the fuel temperature in the fuel tank 22 increases and the evaporated fuel increases does not occur, and the capacity of a canister (not shown) is compared. Can be made smaller. The fuel supply device 20a for the direct injection engine in FIG. 1 has the high-pressure regulator R2 arranged in parallel with the fuel injection valve I. As a modified example in place of this, as shown by the two-dot chain line in FIG. You may comprise the fuel supply apparatus of the cylinder injection engine provided downstream of the delivery pipe 38 equipped with the fuel injection valve I.

In this case, the high-pressure passage 40 extends from the downstream end side of the delivery pipe 38, the high-pressure regulator R2 and the high-pressure return passage r2 are sequentially connected, and the downstream end of this high-pressure return passage r2 is the suction position c of the fuel passage 23. Connected to. As shown by the chain double-dashed line in FIG. 9, in the case of this modified example, a double high pressure passage 40 is formed in the delivery pipe 38, the other end of which is U-shaped and communicates with each other. One end of the passage 40 communicates with the high pressure regulator R2 side. Also in this modification, the high-pressure regulator R2 regulates the fuel pressure in the delivery pipe 38 and the high-pressure passage 40 to a predetermined pressure, and returns the surplus fuel to the suction position c of the fuel passage 23 which is the downstream end of the high-pressure return passage r2. Therefore, since the high-pressure fuel whose temperature has risen is not returned to the fuel tank 22, the problem that the fuel temperature in the fuel tank 22 increases and the evaporated fuel increases does not occur. FIG. 2 shows a fuel supply device 20b for a cylinder injection engine as a second embodiment of the present invention.

Fuel supply device 20 for this direct injection engine
b includes many members that are the same as those of the fuel supply device 20a for the direct injection engine in FIG. 1, and here, the same members are given the same reference numerals and redundant description is omitted. The fuel supply device 20b for the in-cylinder injection engine is provided between the low-pressure pump P1 and the low-pressure pump P1 which are provided in a fuel passage 23 connecting the fuel injection valve I and the fuel tank 22. The high-pressure pump P2, the high-pressure regulator R2 as fuel pressure adjusting means provided in parallel with the fuel injection valve I, and the high-pressure regulator R2 so that the fuel pressure supplied to the fuel injection valve I is adjusted to a set pressure. High pressure return passage r2 for returning excess fuel to the fuel passage 23 and high pressure return passage r
And a low pressure return passage r1 connecting a fuel passage 23 between the low pressure pump P1 and the low pressure pump P1 to the fuel tank 22 via a low pressure regulator R1 as a low pressure fuel adjusting means.

The electric low-pressure pump P1 in the fuel tank 22 has a check valve 27 and a filter 2 as shown in FIG.
8, the discharge side position b, and the fuel passage 23 are sequentially connected. In particular, the discharge side position b of the fuel passage 23 is branched to extend the low pressure return passage r1 whose other end opening reaches the fuel tank 22. The low-pressure return passage r1 is equipped with a low-pressure regulator R1 as low-pressure fuel adjusting means on its way. The low-pressure regulator R1 takes in the low-pressure fuel in the fuel passage 23 at the pilot port e, and sets the fuel pressure in the fuel passage 23 to a predetermined value in accordance with the equilibrium operation of the fuel pressure and the urging force of the compression spring (not shown) in the opposite direction. Then, the excess fuel discharged from the low pressure pump P1 is returned to the fuel tank 22.

In the engine 21 equipped with the fuel supply device for the in-cylinder injection engine of FIG. 2, the electric low-pressure pump P1 first discharges the low-pressure fuel into the fuel passage 23 with good response. The low-pressure fuel that has reached the fuel passage 23 is increased in pressure by the high-pressure pump P2 performing a predetermined pressurization operation, and the fuel discharged from the high-pressure pump P2 passes through the high-pressure passage 40 and each fuel injection valve on the delivery pipe 38 side. When the fuel injection valve I is supplied to the fuel injection valve I, the fuel injection valve I is opened when the drive pulse of the ECU 39 is received, in-cylinder injection of gasoline is executed, and the output torque is generated in the engine 21.

With respect to the suction amount of the high pressure pump P2, the low pressure fuel discharged from the low pressure pump P1 and the high pressure return passage r
In the operating region where the total amount of fuel above 2 is relatively large, the surplus fuel, that is, the low-pressure fuel discharged by the low-pressure pump P1 is returned to the fuel tank 22 through the low-pressure regulator R1 and the low-pressure return passage r1. As a result, the high pressure pump P
The required amount of fuel is always stably supplied to the suction position c of 2. The return fuel in this case is the fuel discharged from the low-pressure pump P1 and is at a relatively low temperature, so that the amount of evaporated fuel in the fuel tank 22 is prevented from increasing. On the other hand, the fuel pressure in the high pressure passage 40 is controlled by the high pressure regulator R.
The pressure is adjusted to a predetermined pressure by 2 and consumed by the fuel injection valve I, and the surplus fuel is returned to the suction position c of the fuel passage 23. As described above, the fuel supply device 20b for the direct injection engine as the second embodiment can always stably supply the required amount of fuel to the suction position c of the high-pressure pump P2. Furthermore,
Excess fuel in the high-pressure fuel from the high-pressure pump P2 passes through the high-pressure regulator R2, reaches the suction position c, is supplied to the high-pressure pump P2 again, is consumed, and is not returned to the fuel tank 22. There is no problem that the fuel temperature inside increases and the evaporated fuel increases.

Further, the fuel passage length L1 between the discharge side position b of the fuel passage 23, which is the upstream end of the low pressure return passage r1, and the suction position c, which is the downstream end of the high pressure return passage r2, is the fuel passage length L1 of the passenger compartment 41. Although it is longer than the length in the longitudinal direction, a fuel passage length L2 between the high pressure pump P2 and the suction position c at the downstream end of the high pressure return passage, and a fuel passage length L3 between the low pressure pump P1 and the low pressure return passage r1. Is set to be sufficiently shorter than the fuel passage length L1. Here, like the fuel supply system of a general engine, the return passages (return passages on the low pressure side and the high pressure side) for returning to the fuel tank side are the fuel passages 23.
The low pressure return path r here
1 and the high pressure return path r2 do not require much length. Therefore, the fuel passage 23 provided as a single pipe-like pipe has a relatively large number of parts, the pipe as a whole of the fuel supply device is relatively short, and waste can be eliminated.
Easy to reduce cost.

FIG. 3 shows a fuel supply system 20c for a cylinder injection engine as a third embodiment of the present invention. The fuel supply device 20c for the direct injection engine includes many members that are the same as those of the fuel supply device 20a for the direct injection engine in FIG.
Here, the same members are denoted by the same reference numerals, and duplicate description is omitted.
The fuel supply device 20c for the in-cylinder injection engine is provided between the low-pressure pump P1 and the low-pressure pump P1 and the fuel injection valve I, which is interposed in the fuel passage 23 that connects the fuel injection valve I and the fuel tank 22. The high-pressure pump P2 and the high-pressure regulator R2 as fuel pressure adjusting means connected downstream of the fuel injection valve I so that the fuel pressure supplied to the fuel injection valve I is adjusted to a set pressure. High-pressure return passage r2 for returning the surplus fuel to the suction position c of the fuel passage 23, and a second branch from the high-pressure return passage r2, the downstream of which is connected to the fuel tank 22 side.
A return passage rd and a switching valve means 42 for switching so as to guide the surplus fuel to either the suction position c at the downstream end of the high-pressure return passage r2 or the second return passage rd.

The discharge side position b of the filter 28 in the fuel passage 23 is connected to the fuel tank 2 via the low pressure regulator R1.
A low-pressure return passage r1 connected to the No. 2 is provided. The electromagnetic actuator (not shown) of the switching valve means 42 has an EC
A U39c (which has the same configuration as that of the ECU 39a in FIG. 1 except that only a control program is partially different) is connected, and the ECU 39c is configured to remove excess fuel from the low pressure pump particularly in a normal operating state other than when the internal combustion engine is started. The upstream side has a function of performing switching control so as to lead to the second return passage rd at the time of start-up in a specific operation state. It should be noted that the specific operating state is set to an operating range before the start is completed (operating range below a predetermined cranking speed), and the high pressure pump P
The discharge pressure of 2 is set as an operating range in a state where the discharge pressure is not sufficient. Therefore, the discharge pressure of the high-pressure pump P2 is low before the start is completed. Even in this case, however, the discharge pressure of the electric low-pressure pump P1 is applied to the fuel injection valve I with good responsiveness through the high-pressure pump P2 and the fuel supply at the start Is possible.

It is assumed that the engine 21 equipped with the fuel supply device for the in-cylinder injection engine shown in FIG. 3 is started by turning on a key switch (not shown). in this case,
First, the electric low-pressure pump P1 discharges the low-pressure fuel into the fuel passage 23 with good responsiveness. The low-pressure fuel that has reached the fuel passage 23 passes through the high-pressure pump P2 in the initial stage of startup and is added to the fuel injection valve I. Thereafter, as the engine speed increases, the low-pressure fuel is pressurized to a high pressure by the high-pressure pump P2. Was converted into
It is supplied to each fuel injection valve I on the delivery pipe 38 side through the high-pressure passage 40, and each fuel injection valve I is opened when a drive pulse of the ECU 39c is received to execute in-cylinder injection of gasoline to cause the engine 21 to perform. Generating output torque.

The high-pressure pump P2 starts to be driven at the time of starting. At this time, the switching valve means 42 downstream of the high-pressure regulator R2 responds to the ON signal output from the ECU 39c at the time of starting the second switching position. It is switched to s2. After that, when the surplus fuel passes through the high pressure regulator r2 in the normal operation state, the delivery pipe 38
And bubbles that have accumulated in the high-pressure return passage r2
Bubbles can be removed by being returned to the fuel tank 22 through the return passage rd. After the normal operation is completed for a predetermined time, the ECU 39c outputs an OFF signal to the switching valve means 42 to switch the switching valve means 42 to the first switching position s1. The switching valve means 42 determines whether there is no problem even if excess fuel is returned to the fuel tank, based on the detection means for detecting the fuel temperature in the fuel tank 22 or the operating state detection means for the engine, It may be controlled to switch to the second switching position s2 if there is no problem and to switch to the first switching position s1 if there is a problem.

During normal operation after completion of start-up, in the operating region where the total amount of the low pressure fuel discharged from the low pressure pump P1 and the fuel from the high pressure return passage r2 is relatively large with respect to the suction amount of the high pressure pump P2. The surplus fuel is returned to the fuel tank 22 via the low pressure regulator R1, and the required amount of fuel is always stably supplied to the suction position c of the high pressure pump P2. The return fuel in this case is the fuel discharged from the low-pressure pump P1 and has a relatively low temperature.
Increasing the evaporated fuel in the fuel tank 22 is prevented.

On the other hand, the fuel pressure in the high-pressure passage 40 is adjusted to a predetermined pressure by the high-pressure regulator R2 and consumed by the fuel injection valve I, and the surplus fuel is passed through the switching valve means 42 at the first switching position s1 to the fuel passage 23. It is returned to the suction position c. Therefore, the required amount of fuel can always be stably supplied to the suction position c of the high-pressure pump P2, and the surplus fuel is not returned to the fuel tank 22, so the fuel temperature in the fuel tank 22 increases and the evaporated fuel increases. Does not cause the problem of doing. It should be noted that the second return passage r communicating when the switching valve means 42 is switched to the second switching position s2.
Although d is directly returned to the fuel tank 22 in FIG. 3, instead of this, as shown by a two-dot chain line in FIG. 3, the downstream end of the second return passage rd is connected to the low pressure regulator R1 and the discharge side position. It may be connected to the low-pressure return passage r1 between it and b.

FIG. 4 shows a fuel supply device 20d for a cylinder injection engine as a fourth embodiment of the present invention. The fuel supply device 20d for the direct injection engine includes many members that are the same as those of the fuel supply device 20c for the direct injection engine in FIG.
Here, the same members are denoted by the same reference numerals, and duplicate description is omitted.

This cylinder injection engine fuel supply device 20
c is a low-pressure pump P1 interposed in a fuel passage 23 connecting the fuel injection valve I and the fuel tank 22, and a low-pressure pump P.
1 and the fuel injection valve I provided between the high pressure pump P2
In order to adjust the fuel pressure supplied to the fuel injection valve I to the set pressure, the high pressure regulator R2 as fuel pressure adjusting means connected downstream of the fuel injection valve I and the surplus fuel passing through the high pressure regulator R2 are used as fuel. A high-pressure return passage r2 for returning to the suction position c of the passage 23, a second return passage rd branched from the high-pressure return passage r2 and connected downstream to the fuel tank 22 side, and a suction position at the downstream end of the high-pressure return passage r2. c and the second return passage rd
A switching valve means 42 for switching the excess fuel to any of the above, and a bypass passage rb connecting the upstream and downstream fuel passages 23 of the high-pressure regulator R2.
An opening / closing valve 43 for opening / closing the bypass passage rb is provided. An orifice OS is provided in the bypass passage rb.

Each electromagnetic actuator (not shown) of the switching valve means 42 and the on-off valve 43 has an E as a control means.
Each CU 39d is connected to the ECU 39d,
In particular, in the switching control of the switching valve means 42, switching is performed so that excess fuel is guided upstream of the high-pressure pump P2 in a normal operating state other than when the internal combustion engine is started, and to the second return passage rd when starting in a specific operating state. Open / close valve 43
In the switching control of (1), it has a function of being turned off to operate at the valve closing position q1 in a normal operating state other than when the internal combustion engine is started, and turned on to operate at the valve opening position q2 at the time of starting in the specific operating state. It should be noted that this specific operation state is set to an operation range before the completion of start-up (operation range below a predetermined cranking speed), and is set to an operation range in which the discharge pressure of the high-pressure pump P2 is insufficient.

For this reason, the high pressure pump P2 must be operated before the start is completed.
However, even in this case, the discharge pressure of the electric low-pressure pump P1 is applied to the fuel injection valve I with high responsiveness through the high-pressure pump P2, and the fuel can be supplied at the time of starting. It is assumed that the engine 21 equipped with the fuel supply device for the in-cylinder injection engine shown in FIG. 4 is started by turning on a key switch (not shown). In this case, first, the electric low-pressure pump P1 discharges the low-pressure fuel into the fuel passage 23. The low-pressure fuel that has reached the fuel passage 23 passes through the high-pressure pump P2 at the initial stage of startup and is added to the fuel injection valve I.

At this start, the high-pressure pump P2 starts to drive. At this time, the switching valve means 42 downstream of the high-pressure regulator R2 and the opening / closing valve 43 of the bypass passage rb are output from the ECU 39 as an ON signal. According to the above, the second switching position s2 and the valve opening position q2 are respectively switched. Therefore, the bubbles that have accumulated in the delivery pipe 38 and the high-pressure return passage r2 are returned to the fuel tank 22 from the bypass passage rb, the high-pressure return passage r2, and the second return passage rd at the time of starting, and the bubbles can be removed to start the engine. It is possible to improve the sex. Moreover, the high-pressure regulator R2 can be bypassed at the time of starting, bubbles can be reliably removed, the flow of fuel at the time of starting can be promoted, and startability is improved. Further, the fuel pressure in the fuel injection valve I is set to a pressure slightly lower than the fuel pressure set by the low pressure regulator R1 due to the presence of the orifice OS, and the fuel supply amount at the time of starting can be accurately adjusted.

After the start is completed, the ECU 39d can output an OFF signal to each of the switching valve means 42 and the opening / closing valve 43, switch the switching valve means 42 to the first switching position s1, and switch the opening / closing valve 43 to the closing position q1. . At this time, the low-pressure fuel that has reached the high-pressure pump is the high-pressure pump P2.
The pressure is increased by the pressurizing operation of No. 1, is supplied to each fuel injection valve I on the delivery pipe 38 side through the high pressure passage 40, and is opened when each fuel injection valve I receives a drive pulse of the ECU 39d, and a cylinder of gasoline. The internal injection is executed and the output torque is generated in the engine 21.

The fuel supply device 20d for the direct injection engine of the fourth embodiment has the same effects as the fuel supply device 20c for the direct injection engine of the third embodiment. Since the valve 43 is switched to the valve opening position q2, the bubbles accumulated in the delivery pipe 38 and the high-pressure return passage r2 are bypassed to the high-pressure regulator R2 to bypass the fuel through the bypass passage rb, the high-pressure return passage r2, and the second return passage rd. Since it can be returned to the tank 22, air bubbles can be reliably removed, the flow of fuel at the time of starting can be promoted, and startability is improved. FIG. 5 shows a fuel supply system 20e for a cylinder injection engine as a fifth embodiment of the present invention. The fuel supply device 20e for the direct injection engine includes many members which are the same as those of the fuel supply device 20a for the direct injection engine in FIG. 1, and the same members are denoted by the same reference numerals to omit redundant description.

Fuel supply device 20 for this direct injection engine
e is a low-pressure pump P1 and a low-pressure pump P that are interposed in a fuel passage 23 that connects the fuel injection valve I and the fuel tank 22.
1 and the fuel injection valve I provided between the high pressure pump P2
In order to adjust the fuel pressure supplied to the fuel injection valve I to the set pressure, the high pressure regulator R2 as fuel pressure adjusting means provided in parallel with the fuel injection valve I and the surplus fuel passing through the high pressure regulator R2 are increased in pressure. A high-pressure return passage r2 for returning to the fuel passage 23 between the pump P2 and the low-pressure pump P1 and a second bypass passage rb2 connecting the upstream and downstream fuel passages of the high-pressure pump P2 so as not to pass through the high-pressure regulator R2. Prepare

Here, the second bypass passage rb2 acts as a unique restriction on the fuel passing through the passage, and in particular, to the extent that the discharge pressure of the high-pressure pump P2 can be maintained at a predetermined value during normal operation. It is formed so that flow resistance can be generated. That is, it is set so that a differential pressure is generated between the upstream side and the downstream side of the high pressure regulator R2.
Moreover, when the flow rate is low at the beginning of startup, the fuel discharged from the low pressure pump P1 can be guided to the fuel injection valve I on the delivery pipe 38 side through the fuel passage 23, the second bypass passage rb2, and the high pressure passage 40.

In the engine 21 equipped with the fuel supply device for the in-cylinder injection engine of FIG. 5, the electric low-pressure pump P1 first discharges the low-pressure fuel into the fuel passage 23 with good response. The low-pressure fuel that has reached the fuel passage 23 bypasses the high-pressure pump P2 and the second bypass passage rb2 and the high-pressure passage 4
When the fuel injection valve I on the delivery pipe 38 side is reached as indicated by 0 and each fuel injection valve I receives a drive pulse from the ECU 39, the fuel injection valve I is opened to execute in-cylinder injection of gasoline and generate an output torque in the engine 21. I am letting you. After this start-up operation, during normal operation, the low-pressure fuel discharged from the low-pressure pump P1 is supplied to the suction position c of the high-pressure pump P2, so that the required amount of fuel is always supplied stably. The fuel discharged from the high-pressure pump P2 during the normal operation acts as a restriction on the fuel flowing into the second bypass passage rb2, and causes the high-pressure passage 40 to generate a larger fuel pressure than the fuel passage 23 side. Moreover, the fuel pressure generated here is high in the high pressure passage 40.
At, the high pressure regulator R2 regulates the pressure to a predetermined pressure.

The fuel in the high pressure passage 40 is consumed by the fuel injection valve I, and the surplus fuel is returned to the suction position c of the fuel passage 23 through the second bypass passage rb2 and the high pressure regulator R2. As described above, the fuel supply device 20e for the direct injection engine as the fifth embodiment can always stably supply the required amount of fuel to the suction position c of the high-pressure pump P2. Further, the surplus fuel in the high-pressure fuel from the high-pressure pump P2 passes through the second bypass passage rb2 and the high-pressure regulator R2, is returned to the suction position c, is supplied to the high-pressure pump P2 again, is consumed, and is returned to the fuel tank 22. Therefore, the problem that the temperature of the fuel in the fuel tank 22 increases and the amount of evaporated fuel increases will not occur.

FIG. 6 shows a fuel supply system 20f for a cylinder injection engine as a sixth embodiment of the present invention. The fuel supply device 20f for the direct injection engine includes many members that are the same as those of the fuel supply device 20e for the direct injection engine in FIG.
Here, the same members are denoted by the same reference numerals, and duplicate description is omitted.

Fuel supply device 20 for this cylinder injection engine
f is a low pressure pump P1 interposed in a fuel passage 23 connecting the fuel injection valve I and the fuel tank 22, and a low pressure pump P
1 and the fuel injection valve I provided between the high pressure pump P2
In order to adjust the fuel pressure supplied to the fuel injection valve I to the set pressure, the high pressure regulator R2 as fuel pressure adjusting means provided in parallel with the fuel injection valve I and the surplus fuel passing through the high pressure regulator R2 are increased in pressure. A high-pressure return passage r2 that returns to the fuel passage 23 between the pump P2 and the low-pressure pump P1, and a second bypass passage rb2 that connects the upstream and downstream fuel passages of the high-pressure pump P2 so as not to pass through the high-pressure regulator R2. A second opening / closing valve 44 provided in the second bypass passage rb2 is provided.

Here, the second on-off valve 44 of the second bypass passage rb2 is an electromagnetic actuator (not shown) which is connected to the ECU 39.
f (E in FIG. 3 except that only the control program is partially different)
The same configuration as that of the CU39c is adopted), and the ECU 3
The valve closing position u according to the OFF signal normally output from 9f.
It is held at 1, and is switched to and held at the valve opening position u2 according to the ON signal output at the time of starting. In particular, in the switching control of the second opening / closing valve 44, the ECU 39f has a function of switching to the valve closing position u1 in a normal operating state other than when the internal combustion engine is started and to the valve opening position u2 when starting in the specific operating state. It should be noted that this specific operation state is set to an operation range before the completion of start-up (operation range below a predetermined cranking speed), and is set to an operation range in which the discharge pressure of the high-pressure pump P2 is insufficient.

It is assumed that the engine 21 equipped with the fuel supply device 20f for the in-cylinder injection engine shown in FIG. 6 is started by turning on a key switch (not shown). At the time of starting, the ECU 39f outputs an ON signal to the second opening / closing valve 44, and at this time, the electric low pressure pump P1 discharges the low pressure fuel to the fuel passage 23 with good responsiveness. The low-pressure fuel that has reached the fuel passage 23 bypasses the high-pressure pump P2, reaches the fuel injection valve I on the delivery pipe 38 side through the second bypass passage rb2 and the high-pressure passage 40, and each fuel injection valve I of the ECU 39f. When it receives the drive pulse, it opens to cause in-cylinder injection of gasoline to generate output torque in the engine 21. Immediately after this start-up, when the engine speed increases, the high-pressure pump P2 starts driving, but at this time, the ECU 39f issues an OFF output to the second opening / closing valve 44, and in the subsequent normal operation state, the valve is closed at the valve closing position u1. 2 Hold the on-off valve 44.

As described above, in the fuel supply system 20f for the cylinder injection engine as the sixth embodiment, the high pressure pump P2 which is not in discharge operation at the time of starting can be prevented from acting as a restriction, and the second bypass passage rb2 can be prevented. The bypassed low-pressure fuel of the low-pressure pump P1 can be directly guided to the fuel injection valve I on the delivery pipe 38 side, and the startability can be improved. On the other hand, in the normal operation state, the second bypass passage rb2
Closed, and the high pressure regulator R2 turns the high pressure return passage r2
Since the fuel pressure on the side is adjusted and the surplus fuel is returned to the suction position c, high-pressure injection is possible and the required amount of fuel can always be stably supplied to the suction position c. Further, the surplus fuel in the high pressure fuel from the high pressure pump P2 is sucked in at the suction position c.
Is returned to the high pressure pump P2, is consumed again, and is not returned to the fuel tank 22.
The problem that the fuel temperature in 2 increases and the evaporated fuel increases does not occur.

FIG. 7 shows a fuel supply system 20j for a cylinder injection engine as a seventh embodiment of the present invention. This in-cylinder injection engine fuel supply device 20j has a second opening / closing valve 44 in the in-cylinder injection engine fuel supply device 20e of FIG.
In place of the check valve 45, there are many components that are the same. Here, the same members are designated by the same reference numerals and duplicate description is omitted. The second bypass passage rb2 of the fuel supply device 20j for the direct injection engine is equipped with a check valve 45 that allows only the flow from the fuel passage 23 toward the high pressure passage 40. This check valve 45 bypasses the low-pressure fuel of the low-pressure pump P1 from the fuel passage 23 to the high-pressure pump P2 and bypasses the high-pressure passage 40.
The high pressure fuel in the high pressure passage 40 is prevented from flowing into the fuel passage 23 during normal operation.

It is assumed that the engine 21 equipped with the fuel supply device 20j for the in-cylinder injection engine shown in FIG. 7 is started by turning on a key switch (not shown). At this start, the electric low-pressure pump P1 discharges the low-pressure fuel into the fuel passage 23 with good responsiveness. The low-pressure fuel that has reached the fuel passage 23 bypasses the high-pressure pump P2 and reaches the fuel injection valve I on the delivery pipe 38 side through the check valve 45, the second bypass passage rb2, and the high-pressure passage 40, and each fuel injection valve I Is EC
When it receives a drive pulse of U39f, it opens to cause in-cylinder injection of gasoline to generate output torque in the engine 21.

Immediately after the start, when the engine speed increases, the high pressure pump P2 starts to drive. At this time, the check valve 45 moves the high pressure fuel to the fuel passage 23 as the fuel pressure in the high pressure oil passage 40 increases. The flow is blocked, and the fuel pressure in the high pressure oil passage 40 is regulated by the high pressure regulator R2, and the surplus fuel is returned to the suction position c via the high pressure return passage r2.

As described above, the fuel supply system 20j for the cylinder injection engine as the seventh embodiment can prevent the high pressure pump P2, which is not in discharge operation at the time of starting, from acting as a squeeze, and the second bypass passage rb2 can be prevented. The bypassed low-pressure fuel of the low-pressure pump P1 can be directly guided to the fuel injection valve I on the delivery pipe 38 side, and the startability can be improved. On the other hand, in the normal operation state, the check valve 45 closes the second bypass passage rb2, guides the low-pressure fuel from the low-pressure pump P1 to the fuel injection valve I via the high-pressure pump P2, and the high-pressure regulator R2 moves to the high-pressure return passage r2 side. Since the fuel pressure is adjusted and the surplus fuel is returned to the suction position c, stable high-pressure injection is possible and the required amount of fuel can always be supplied to the suction position c. Further, since the surplus fuel in the high pressure fuel from the high pressure pump P2 is not returned to the fuel tank 22, the problem that the fuel temperature in the fuel tank 22 increases and the evaporated fuel increases does not occur.

In the above description, when the high-pressure pump P2 has a large flow resistance and a sufficient fuel pressure cannot be generated for the fuel injection valve in a specific operating state such as at the time of starting, It is preferable to provide the check valve 45 and the second bypass passage rb2 as shown in the seventh embodiment also in the second to fourth embodiments. The high pressure regulator R2 in the seventh embodiment may be provided on the downstream side of the delivery pipe 38 as shown by the chain double-dashed line in the first embodiment. FIG. 8 shows a fuel supply device 20h for a cylinder injection engine as an eighth embodiment of the present invention.

This cylinder injection engine fuel supply device 20
Compared to the fuel supply device 20f for a direct injection engine in FIG. 6, h has many same components except that a low-pressure return passage r1 is provided on the upstream side of the fuel passage 23. The same reference numerals are given and duplicate description is omitted. Here, the discharge side position b of the fuel passage 23 is branched to extend the low pressure return passage r1 whose other end opening reaches the fuel tank 22. The low-pressure return passage r1 is equipped with a low-pressure regulator R1 as low-pressure fuel adjusting means on its way. The low-pressure regulator R1 takes in the low-pressure fuel in the fuel passage 23 at the pilot port e, and sets the hydraulic pressure in the low-pressure return passage r1 to a predetermined value in accordance with the fuel pressure and a balance operation of a plunger (not shown) that receives the biasing force of a compression spring (not shown) in the opposite direction. The pressure is adjusted to a value, and the surplus fuel discharged from the low pressure pump P1 is returned to the fuel tank 22.

A switching valve means 44 is provided in the second bypass passage rb2, and an OFF signal normally output from the ECU 39h (which has the same configuration as that of the ECU 39f of FIG. 6 except that only a control program is partially different) is provided. Accordingly, it is held at the valve closing position u1 and is switched and held at the valve opening position u2 according to the ON signal output at the time of starting. The electromagnetic actuator (not shown) of the switching valve means 44 includes the ECU 3
9h is connected, and the ECU 39h has the same control function as the ECU 39f.

It is assumed that the engine 21 equipped with the fuel supply device 20h for the cylinder injection engine shown in FIG. 8 is started by turning on a key switch (not shown). At the time of starting, the ECU 39h outputs an ON signal to the second opening / closing valve 44, and at this time, the electric low pressure pump P1 discharges the low pressure fuel to the fuel passage 23 with good responsiveness. The low-pressure fuel that has reached the fuel passage 23 bypasses the high-pressure pump P2 and reaches the fuel injection valve I on the delivery pipe 38 side through the second bypass passage rb2 and the high-pressure passage 40, and each fuel injection valve I causes the drive pulse of the ECU 39f. When the engine 21 is received, it is opened to cause in-cylinder injection of gasoline to generate output torque in the engine 21.

Immediately after this start, when the engine speed increases, the high-pressure pump P2 starts to drive, but at this time, the second opening / closing valve 44 of the high-pressure passage 40 is switched to the closed position u1 by the ECU 39h and is held at a high pressure. The flow of fuel to the fuel passage 23 is blocked, the hydraulic pressure in the high-pressure oil passage 40 is adjusted by the high-pressure regulator R2, and the surplus fuel is returned to the suction position c.

At the time of normal operation after this start-up operation, in the operating region where the total amount of the low-pressure fuel discharged from the low-pressure pump P1 and the fuel from the high-pressure return passage r2 is relatively large with respect to the suction amount of the high-pressure pump P2. The low-pressure fuel discharged from the low-pressure pump P1 which is the surplus fuel is the low-pressure regulator R.
1 and the low-pressure return passage r1 to be returned to the fuel tank 22. As a result, the required amount of fuel is always stably supplied to the suction position c of the high-pressure pump P2. The return fuel in this case is the fuel discharged from the low-pressure pump P1 and is at a relatively low temperature, so that the amount of evaporated fuel in the fuel tank 22 is prevented from increasing.

On the other hand, after the second on-off valve 44 is held at the valve closing position u1, the fuel pressure in the high-pressure passage 40 is adjusted to a predetermined pressure by the high-pressure regulator R2, consumed by the fuel injection valve I, and surplus fuel is discharged. It is returned to the suction position c of the fuel passage 23. As described above, the fuel supply device 20h for the direct injection engine as the eighth embodiment can always stably supply the required amount of fuel to the suction position c of the high-pressure pump P2. Furthermore,
Excess fuel from the high-pressure pump P2 is supplied to the high-pressure pump P2 again from the suction position c and is consumed.
Since the fuel is not returned to the fuel tank 22, the problem that the fuel temperature in the fuel tank 22 increases and the evaporated fuel increases does not occur.

Further, the fuel passage length L1 'between the discharge side position b of the fuel passage 23, which is the upstream end of the low pressure return passage r1, and the suction position c, which is the downstream end of the high pressure return passage r2, is the passenger compartment 41. (See FIG. 10), the fuel passage length L2 ′ between the high-pressure pump P2 and the suction position c at the downstream end of the high-pressure return passage, and between the low-pressure pump P1 and the low-pressure return passage r1. Fuel passage length L
It is set to be sufficiently longer than 3 '. That is, as shown in FIG. 10, the fuel passage length L2 ′ is equal to or longer than the length in the longitudinal direction of the vehicle interior 41, but this portion is formed as a single pipe-shaped pipe, and this portion is formed by a plurality of pipes. As compared with the case where the above is adopted, since a single pipe is used, waste of the pipe can be eliminated and the cost can be easily reduced.

FIG. 11 shows a fuel supply device 20i for a diesel engine as a ninth embodiment of the present invention. As shown in FIG. 11, this fuel supply device 20i is provided with a low-pressure pump P1 inside the fuel tank 22, which pressurizes the fuel in the fuel tank 22 and supplies it to the fuel injection valve I side. Further, a check valve 27 and a filter 28 are sequentially provided in the fuel passage 23 between the low-pressure pump P1 and the fuel injection valve I, and further, a distribution type that supplies high-pressure fuel to each fuel injection valve I. The high-pressure fuel injection pump P2 is provided. Although the distributed high-pressure fuel injection pump P2 is provided in this embodiment, a column high-pressure fuel injection pump may be used. Further, a high-pressure return passage r2 is provided to connect the surplus fuel generated after the fuel injection of each fuel injection valve I to the suction position c on the upstream side of the high-pressure fuel injection pump P2.

Next, the fuel injection valve I here will be described. In this fuel injection valve I, as shown in FIG. 12, an injection hole 51 is formed at the tip of the holder body 50, and
A needle 53 is slidably provided inside thereof. The needle 53 is formed by a spring member (spring) 52 of a spring chamber formed on the opposite side of the injection hole 51.
Is biased to the side. The needle 53 communicates with the high-pressure fuel injection pump P2 side, and the holder body 50
When the high-pressure fuel metered by the high-pressure pump P2 is applied to the oil reservoir 54 formed between the needle 53 and the holder body 50 via the fuel passage 55 formed in the By moving upwards against the injection hole 51
Is opened to inject fuel into a combustion chamber (not shown).

When the high pressure fuel from the high pressure fuel injection pump P2 is no longer applied, the injection is terminated and the needle 53 returns to the original state in which the injection hole 51 is closed. In this case, excess fuel flows toward the spring chamber from the gap between the holder body 50 and the needle 53, but in order to prevent the excess fuel from increasing the internal pressure in the spring chamber and suppressing the operation of the needle 53, An escape passage 56 for releasing the excess fuel is formed inside the adjusting screw 57. This escape passage 56 is a high pressure return passage r2.
It is connected to the.

As described above, also in the fuel supply device 20i for the diesel engine of the ninth embodiment, the surplus fuel, which has been heated to a high temperature by the high-pressure fuel injection pump P2 and has a high temperature, is stored in the fuel tank 22 as in the above-described embodiments. Since the fuel is not returned, the temperature of the fuel in the fuel tank 22 can be prevented from increasing and the evaporated fuel can be prevented from increasing. Also, the high pressure return passage r
Since 2 is not returned to the fuel tank 22, it is advantageous in terms of piping, and there is an effect that cost can be reduced.

In the above description, the present invention is not limited to the above-mentioned embodiments, and the engine 21 is mounted in the fuel supply system of the four-cylinder DOHC gasoline engine. It can be mounted on a cylinder gasoline engine or a multi-cylinder engine using alcohol fuel other than gasoline. Further, although the high-pressure pump is an engine-driven type in the present invention, it may be a motor-driven type. Furthermore, although each of the above-described embodiments relates to the in-cylinder injection type engine in which the fuel injection valve directly faces the combustion chamber, the present invention is also applicable to the intake port injection type engine.

[0081]

As described above, according to the first aspect of the invention, the fuel in the fuel tank is sequentially pressurized by the low pressure pump and the high pressure pump, and the fuel pressure is provided in parallel with the fuel injection valve or downstream of the injection valve. The adjusting means adjusts the high-pressure fuel to the set pressure as the fuel pressure supplied to the fuel injection valve, and in particular, the high pressure for returning the surplus fuel passing through the fuel pressure adjusting means to the fuel passage between the high pressure pump and the low pressure pump. Since the return passage is provided, the excess fuel can be restricted from returning to the fuel tank. Therefore, it is possible to reduce the generation of evaporated fuel in the fuel tank, and since the high pressure return passage is connected to the fuel passage between the high pressure pump and the low pressure pump, it is easy to shorten the high pressure return passage and simplify it. The layout is advantageous, and the return path does not need to extend to the fuel tank. In this case, the piping can be saved, which is advantageous in terms of cost.

According to a second aspect of the present invention, in the fuel supply system for an internal combustion engine according to the first aspect, particularly, the fuel passage between the high pressure return passage and the low pressure pump is connected to the fuel tank via the low pressure fuel adjusting means. Since the low pressure return passage is used, the low pressure fuel adjusting means adjusts the fuel pressure of the low pressure fuel to a predetermined value. Therefore, the fuel pressure from the low pressure pump can be stabilized, and the suction pressure of the high pressure pump can be stably secured.

According to a third aspect of the present invention, in the fuel supply system for an internal combustion engine according to the second aspect, in particular, the upstream end of the low pressure return passage is located upstream of the downstream end of the high pressure return passage. Can be sufficiently separated from the upstream end of the high pressure return passage. Therefore, a single pipe is required between the upstream end of the low-pressure return passage and the downstream end of the high-pressure return passage, and the waste of the pipe in this portion can be eliminated and simplified, which is advantageous in terms of cost.

According to a fourth aspect of the present invention, in the fuel supply system for an internal combustion engine according to the third aspect, particularly, the fuel passage length between the upstream end of the low pressure return passage and the downstream end of the high pressure return passage is high pressure pump. And a fuel passage length between the low pressure pump and the downstream end of the high pressure return passage, and a fuel passage length between the low pressure pump and the low pressure return passage. Therefore, a single pipe suffices for a relatively long time between the upstream end of the low-pressure return passage and the downstream end of the high-pressure return passage, and the waste of the pipe in this portion can be eliminated and simplified, which is particularly advantageous in terms of cost. .

According to a fifth aspect of the invention, in the fuel supply system for an internal combustion engine according to the first aspect, in particular, the fuel pressure adjusting means is connected to the downstream side of the fuel injection valve, branches from the high pressure return passage, and the downstream side thereof is the fuel tank. Since the second return passage connected to the side is provided and the switching valve means for switching the excess fuel to either the downstream end of the high pressure return passage or the second return passage is provided, the switching valve means is provided. The excess fuel after passing through the fuel pressure adjusting means is selectively guided to the downstream end of the high-pressure return passage and the fuel tank side in accordance with the switching of. For this reason, it is possible to reduce the generation of evaporated fuel in the fuel tank, and it is possible to return the surplus fuel to the fuel tank in accordance with the need for removing air bubbles or the like.

According to a sixth aspect of the present invention, in the fuel supply system for an internal combustion engine according to the fifth aspect, particularly, the switching valve means is controlled by the control means, and excess fuel is supplied upstream of the high pressure pump in a normal operating state of the internal combustion engine. , Second in a specific operating state
Since it is guided to the return passage, the surplus fuel after passing through the fuel pressure adjusting means is selectively introduced to the downstream end of the high pressure return passage and the fuel tank side according to the normal operating state and the specific operating state. Therefore, it is possible to reduce the generation of evaporated fuel in the fuel tank in the normal operation state, and it is possible to return the surplus fuel to the fuel tank in the specific operation state according to the need such as bubble removal.

According to a seventh aspect of the present invention, in the fuel supply system for an internal combustion engine according to the fifth aspect, the fuel passage portions on the upstream side and the downstream side of the fuel pressure adjusting means are connected by a bypass passage provided with an opening / closing valve. Therefore, the bypass passage can be opened and closed as needed. Therefore, the characteristics of the fuel supply system can be improved by opening and closing the bypass passage according to the engine operating state.

According to an eighth aspect of the present invention, in the fuel supply system for an internal combustion engine according to the seventh aspect, in particular, the on-off valve is controlled by the control means, and the on-off valve is closed in the normal operating state of the internal combustion engine, and the specific operating state Since it is opened, the bypass passage can be opened / closed as required in the normal operation state and the specific operation state. Therefore, it is possible to improve the air bleeding and startability by opening the bypass passage in the specific operation state.

The invention according to claim 9 is claim 6 or claim 8.
In the fuel supply device for an internal combustion engine as described above, the specific operation state, in particular, the state in which the discharge pressure of the high-pressure pump is not sufficient is set, so that the operation can be performed in this state. Therefore, even when the discharge pressure of the high-pressure pump is not sufficient, the excess fuel after passing through the fuel pressure adjusting means is returned to the fuel tank side by the second return passage, or the bypass passage is opened to bypass the fuel pressure adjusting means to start. It is possible to improve the sex.

According to a tenth aspect of the invention, in the fuel supply system for an internal combustion engine according to the ninth aspect, in particular, the high pressure pump is driven by the internal combustion engine, and the specific operating state is when the internal combustion engine is started. The high-pressure pump can be driven when the engine is driven, and at the time of start-up, surplus fuel after passing through the fuel pressure adjusting means can be returned to the fuel tank side by the second return passage. Therefore, at the time of start-up, the bypass passage can be opened to bypass the fuel pressure adjusting means to remove air bubbles.

According to the eleventh aspect of the invention, in the fuel supply system for an internal combustion engine according to the first aspect, the second bypass passage connecting the upstream and downstream fuel passages of the high pressure pump so as not to pass through the fuel pressure adjusting means. Arranged. Therefore, the high-pressure pump generates a discharge pressure according to the flow path resistance of the second bypass passage, enables high-pressure injection, and also bypasses the fuel pressure adjusting means at the time of starting to supply the fuel to the fuel injection valve to improve startability. Can be improved.

According to a twelfth aspect of the present invention, in the fuel supply system for an internal combustion engine according to the eleventh aspect, particularly, since the opening / closing valve is arranged in the second bypass passage, the opening / closing of the second bypass passage can be switched. Therefore, when the second bypass passage is closed, the high-pressure pump can generate a predetermined discharge pressure to enable high-pressure injection, and when it is opened, the fuel of the low-pressure pump can be directly supplied to the fuel injection valve through the second bypass passage. You can secure the sex.

According to a thirteenth aspect of the present invention, in the fuel supply system for an internal combustion engine according to the twelfth aspect, the on-off valve is controlled so as to be closed so that it is closed in a normal operation state of the internal combustion engine and opened in a specific operation state. With the provision of the means, the control means can switch between opening and closing the second bypass passage. Therefore, the control means can surely close the second bypass passage in the normal operation state and open it in the specific operation state to enable high-pressure injection, and when opening the fuel of the low-pressure pump through the second bypass passage, the fuel injection valve. Fuel can be directly supplied to the engine, and startability can be secured.

According to a fourteenth aspect of the present invention, in the fuel supply system for an internal combustion engine according to the thirteenth aspect, since the specific operating state, particularly the state in which the discharge pressure of the high pressure pump is not sufficient, is set, the switching operation is performed in this state. Can be done. Therefore, even when the discharge pressure of the high-pressure pump is not sufficient, the second bypass passage can be opened and the fuel of the low-pressure pump can be directly supplied to the fuel injection valve through the second bypass passage, so that the startability can be ensured.

According to a fifteenth aspect of the present invention, in the fuel supply apparatus for an internal combustion engine according to the fourteenth aspect, the high pressure pump is driven by the internal combustion engine, and the specific operation state is when the internal combustion engine is started. The high-pressure pump can operate. Therefore, the high-pressure pump can be driven when the internal combustion engine is driven, and at the time of start-up, even if the discharge pressure of the high-pressure pump is not sufficient, the fuel of the low-pressure pump can be directly supplied to the fuel injection valve through the second bypass passage, and the startability is improved. Can be secured.

According to a sixteenth aspect of the present invention, in the fuel supply system for an internal combustion engine according to the eleventh aspect, in the second bypass passage,
Especially, since the check valve is provided, the check valve can open and close the second bypass passage. Therefore, the check valve can be operated so as to sufficiently secure the discharge pressure of the high-pressure pump, and at the time of startup, the fuel of the low-pressure pump can be directly supplied to the fuel injection valve through the second bypass passage, and the startability can be ensured.

According to the seventeenth aspect of the invention, in the fuel supply system for an internal combustion engine according to the twelfth or sixteenth aspect, a low pressure return passage for returning the fuel upstream of the high pressure pump to the fuel tank via the low pressure regulator is provided. Even in an operating range in which there is a relatively large amount of surplus fuel with respect to the suction amount of the high-pressure pump, the surplus fuel is returned to the high-pressure pump again, and the surplus fuel in the low-pressure fuel discharged by the low-pressure pump P1 is the fuel tank. Returned to. Therefore, the required amount of fuel is always stably supplied to the suction position c of the high-pressure pump P2, the temperature rise in the fuel tank can be regulated, and the generation of evaporated fuel can be reduced.

According to the eighteenth aspect of the present invention, in the fuel supply system for an internal combustion engine according to the seventeenth aspect, the upstream side of the low pressure return passage is located downstream of the high pressure return passage and upstream of the upstream end of the second bypass passage. Therefore, it is easy to secure a relatively long length by a single pipe between the low pressure return passage and the downstream side of the high pressure return passage and the second bypass passage. For this reason, the portion of the single pipe becomes longer, the high-pressure return passage, the second bypass passage, and the low-pressure return passage can be set shorter, and the cost can be reduced by simplifying the pipe.

According to a nineteenth aspect of the present invention, in the fuel supply system for an internal combustion engine according to the eighteenth aspect, an upstream side of the low pressure return passage is provided close to the low pressure pump, and a downstream end of the high pressure return passage and the second bypass. Since the upstream end of the passage is provided close to the high pressure pump, it becomes easy to secure a relatively long distance between the upstream side of the low pressure return passage and the downstream end side of the high pressure return passage. Therefore, the length of the single pipe becomes longer, the high-pressure return passage, the second bypass passage, and the low-pressure return passage can be set shorter, and the cost can be reduced by simplifying the pipe.

According to a twentieth aspect of the present invention, the fuel in the fuel tank is sequentially pressurized by the low-pressure pump and the high-pressure pump, and the high-pressure fuel is supplied to the fuel injection valve that opens at a fuel pressure of a predetermined value or higher. Since a high-pressure return passage for returning the excess fuel passing through the fuel injection valve to the fuel passage between the high-pressure pump and the low-pressure pump is provided, excess fuel that has been heated to a high temperature by the high-pressure pump and returns to the fuel tank Can be regulated. Therefore, it is possible to prevent the temperature of the fuel in the fuel tank from increasing and the amount of evaporated fuel to increase. Moreover, since the high-pressure return passage is not returned to the fuel tank, the high-pressure return passage can be shortened and easily simplified, which is advantageous in terms of piping, and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a fuel supply device for a direct injection engine as a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a fuel supply system for a cylinder injection engine as a second embodiment of the present invention.

FIG. 3 is a schematic configuration diagram of a fuel supply device for a cylinder injection engine as a third embodiment of the present invention.

FIG. 4 is a schematic configuration diagram of a fuel supply system for a cylinder injection engine as a fourth embodiment of the present invention.

FIG. 5 is a schematic configuration diagram of a fuel supply system for a cylinder injection engine as a fifth embodiment of the present invention.

FIG. 6 is a schematic configuration diagram of a fuel supply system for a cylinder injection engine as a sixth embodiment of the present invention.

FIG. 7 is a schematic configuration diagram of a fuel supply system for a cylinder injection engine as a seventh embodiment of the present invention.

FIG. 8 is a schematic configuration diagram of a fuel supply system for a cylinder injection engine as an eighth embodiment of the present invention.

FIG. 9 is a vertical cross-sectional view of a direct injection engine as a first embodiment of the present invention.

FIG. 10 is a schematic layout diagram of a vehicle equipped with a cylinder injection engine as a first embodiment of the present invention.

FIG. 11 is a schematic configuration diagram of a fuel supply device for a diesel engine as a ninth embodiment of the present invention.

12 is a cross-sectional view of a fuel injection valve used in the fuel supply system of FIG.

FIG. 13 is a schematic configuration diagram of a fuel supply device for a conventional cylinder injection engine.

[Explanation of symbols]

 20a to 20i Fuel supply device for in-cylinder injection engine 21 Engine 22 Fuel tank 23 Fuel passage 28 Filter 38 Delivery pipe 39a, 39c, 39d, 39f, 39h ECU 40 High pressure passage a Pilot port c Suction position b Discharge side position e Pilot port rb Bypass passage rb2 Second bypass passage rd Second return passage r1 Low pressure return passage r2 High pressure return passage I Fuel injection valve P1 Low pressure pump P2 High pressure pump R1 Low pressure regulator R2 High pressure regulator

Claims (20)

[Claims] 1. A low-pressure pump interposed in a fuel passage connecting a fuel injection valve and a fuel tank, a high-pressure pump provided between the low-pressure pump and the fuel injection valve, and to the fuel injection valve. In order to adjust the supply fuel pressure to the set pressure, the fuel pressure adjusting means provided in parallel with the fuel injection valve or downstream of the injection valve, and the surplus fuel passing through the fuel pressure adjusting means are supplied to the high pressure pump and the low pressure. A fuel supply device for an internal combustion engine, comprising: a high-pressure return passage for returning to a fuel passage between the pump and the pump. 2. A fuel supply system for an internal combustion engine according to claim 1, further comprising a low pressure return passage for connecting a fuel passage between the high pressure return passage and the low pressure pump to a fuel tank via the low pressure fuel adjusting means. A fuel supply device for an internal combustion engine, comprising: 3. The fuel supply system for an internal combustion engine according to claim 2, wherein an upstream end of the low pressure return passage is located upstream of a downstream end of the high pressure return passage. . 4. The fuel supply system for an internal combustion engine according to claim 3, wherein the fuel passage length between the upstream end of the low pressure return passage and the downstream end of the high pressure return passage is the high pressure pump and the high pressure return passage downstream. A fuel supply device for an internal combustion engine, which is longer than a fuel passage length between the end and a fuel passage between the low pressure pump and the low pressure return passage. 5. The fuel supply system for an internal combustion engine according to claim 1, wherein the fuel pressure adjusting means is connected to a downstream side of the fuel injection valve, branches from the high pressure return passage, and the downstream side is connected to a fuel tank side. A fuel for an internal combustion engine, characterized in that a second return passage is provided, and a switching valve means for switching the excess fuel to either the downstream end of the high pressure return passage or the second return passage is provided. Supply device. 6. The fuel supply system for an internal combustion engine according to claim 5, wherein the switching valve means supplies the excess fuel to the upstream of the low pressure pump in the normal operation state of the internal combustion engine and to the second return passage in the specific operation state. A fuel supply device for an internal combustion engine, comprising a control means for switching control. 7. A fuel supply system for an internal combustion engine according to claim 5, wherein a bypass passage connecting the upstream side and the downstream side fuel passage portion of the fuel pressure adjusting means is provided, and the bypass passage is opened and closed. A fuel supply device for an internal combustion engine, comprising an on-off valve. 8. A fuel supply system for an internal combustion engine according to claim 7, wherein the opening / closing valve is provided with a control means for controlling the opening / closing so as to be closed in a normal operation state of the internal combustion engine and opened in a specific operation state. A characteristic fuel supply device for an internal combustion engine. 9. The fuel supply system for an internal combustion engine according to claim 6 or 8, wherein the specific operating state is a state in which the discharge pressure of the high-pressure pump is not sufficient. . 10. The fuel supply system for an internal combustion engine according to claim 9, wherein the high-pressure pump is driven by the internal combustion engine, and the specific operation state is when the internal combustion engine is started. Supply device. 11. A fuel supply system for an internal combustion engine according to claim 1, further comprising a second bypass passage connecting the fuel passages upstream and downstream of the high pressure pump so as not to pass through the fuel pressure adjusting means. A fuel supply device for an internal combustion engine, comprising: 12. The fuel supply system for an internal combustion engine according to claim 11, wherein an opening / closing valve is arranged in the second bypass passage. 13. A fuel supply system for an internal combustion engine according to claim 12, wherein the opening / closing valve is provided with a control means for controlling the opening / closing so as to be closed in a normal operation state of the internal combustion engine and opened in a specific operation state. A characteristic fuel supply device for an internal combustion engine. 14. The fuel supply system for an internal combustion engine according to claim 13, wherein the specific operation state is a state in which the discharge pressure of the high pressure pump is not sufficient. 15. The fuel supply system for an internal combustion engine according to claim 14, wherein the high pressure pump is driven by the internal combustion engine, and the specific operating state is when the internal combustion engine is started. apparatus. 16. The fuel supply system for an internal combustion engine according to claim 11, wherein a check valve is provided in the second bypass passage. 17. The fuel supply system for an internal combustion engine according to claim 12 or 16, further comprising a low pressure return passage for returning the upstream fuel to the fuel tank from the high pressure pump via the low pressure regulator. Fuel supply device for internal combustion engine. 18. A fuel supply system for an internal combustion engine according to claim 17, wherein the upstream side of the low pressure passage is located downstream of the high pressure return passage and upstream of the upstream end of the second bypass passage. Fuel supply device for internal combustion engine. 19. The fuel supply system for an internal combustion engine according to claim 18, wherein the upstream side of the low-pressure passage is provided close to the low-pressure pump, and the downstream end of the high-pressure return passage and the upstream end of the second bypass passage are provided. , A fuel supply device for an internal combustion engine, which is provided in the vicinity of a high-pressure pump. 20. A fuel injection valve which opens when the fuel pressure exceeds a predetermined value, a low pressure pump interposed in a fuel passage connecting the fuel injection valve and a fuel tank, the low pressure pump and the fuel injection valve. An internal combustion engine having a high-pressure pump provided between the fuel injection valve and a high-pressure return passage for returning excess fuel passing through the fuel injection valve to a fuel passage between the high-pressure pump and the low-pressure pump. Fuel supply system.