JPH10227269A - Fuel pressure fluctuation reduction device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel pressure fluctuation reduction device which can provide a high durability and reduce the assembly man-hour of a fuel supply system. SOLUTION: By building an accumulator 8 in a fuel filter 3 provided between a low pressure pump and a high pressure pump, the pressure fluctuation of a fuel transferred from the high pressure pump to the fuel filter 3 can be reduced. Therefore, the durability of the low pressure pump, fuel supply piping and the inner member of the fuel filter 3 can be ensured. As the accumulator 8 encloses an filling gas 82 in a space surrounded by a partition 81, a metal bellows 83 and a bottom member 84, a higher durability is ensured in comparison with a pulsation damper having a rubber diaphragm. As the fuel filter 3 builds in the accumulator 8, the number of parts of the fuel supply system can be reduced and the assembly of the fuel supply system is facilitated and an assembly man-hour can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an internal combustion engine (hereinafter referred to as "internal combustion engine").
The present invention relates to a fuel pressure fluctuation reduction device used in a fuel supply system of an "internal combustion engine".

[0002]

2. Description of the Related Art Conventionally, in a fuel supply system for an engine, a pulsation damper is provided in a fuel filter as disclosed in Japanese Patent Application Laid-Open No. H8-210211. 2. Description of the Related Art There is known a fuel pressure fluctuation reducing device that is disposed on a path to suppress fluctuations in fuel pressure. The pulsation damper has a rubber diaphragm and a spring, and the diaphragm and the spring respond to the fuel pressure to attenuate the fluctuation of the fuel pressure.

[0003]

However, in a fuel supply system in which the low-pressure fuel pumped from the fuel tank by the low-pressure pump is further pressurized by the high-pressure pump and supplied to the injector, a fuel supply system using a conventional low-pressure pump alone is not provided. Higher fuel pressure fluctuations occur. Therefore, in the fuel pressure fluctuation reducing device disclosed in Japanese Patent Application Laid-Open No. H8-210211, since the pulsation damper having the rubber diaphragm is used, the diaphragm may be deteriorated. Also,
If the diaphragm is used while being deteriorated, there is a problem that the durability of the low-pressure pump, the fuel supply pipe and the fuel filter is reduced.

The present invention has been made to solve such a problem, and an object of the present invention is to provide a fuel pressure fluctuation reducing device having high durability. Another object of the present invention is to provide a fuel pressure fluctuation reduction device capable of greatly reducing fuel pressure fluctuation. It is still another object of the present invention to provide a fuel pressure fluctuation reducing device capable of reducing the number of assembling steps of a fuel supply system.

[0005]

According to the fuel pressure fluctuation reducing device of the first aspect of the present invention, an accumulator responsive to fuel pressure is provided in a fuel supply path between a low pressure pump and a high pressure pump. Fluctuations in fuel pressure generated from the high-pressure pump toward the low-pressure pump can be reduced. Therefore, the durability of the low-pressure pump, the fuel supply pipe, the fuel filter, and the like can be ensured.

According to the fuel pressure fluctuation reducing device of the second aspect of the present invention, the accumulator having the metal bellows and the partition plate fills the gas into the space formed by the metal bellows and the partition plate. It can withstand high fuel pressure fluctuations. Therefore, in the configuration using the accumulator, higher durability can be secured as compared with the configuration using the pulsation damper.

According to the fuel pressure fluctuation reducing device according to the third aspect of the present invention, since the fuel filter provided in the fuel supply path between the low pressure pump and the high pressure pump has a built-in accumulator, the number of parts of the fuel supply system is reduced. Is reduced.
Therefore, the fuel supply system can be easily assembled,
Assembly time is reduced.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 shows a fuel supply system for an engine using a fuel pressure fluctuation reducing device according to one embodiment of the present invention. The low-pressure pump 1 is driven by a motor, and supplies the fuel inside the fuel tank 6 to the high-pressure pump 5 via the fuel supply pipe 2, the fuel filter 3 including the accumulator 8, and the fuel supply pipe 4. The high-pressure pump 5 is driven by a crankshaft, a valve camshaft and the like (not shown) of the engine, pressurizes the low-pressure fuel introduced from the low-pressure pump 1, supplies the low-pressure fuel to the accumulator 10 via the fuel supply pipe 11, and The discharge amount is electronically controlled by the check valve 9 so that the pressure becomes the optimum pressure. The high-pressure fuel supplied to the accumulator 10 is injected from each injector 12 into each cylinder. Excess fuel on the low pressure side of the high pressure pump 5 is returned to the fuel tank 6 via the fuel return pipe 13 by the check valve 7 together with the vapor generated inside the high pressure pump 5.

Next, details of the fuel filter 3 will be described with reference to FIG. The fuel filter 3 includes a housing 31, a filter paper 32, an element 33, a stopper 34, a fuel inlet connection 35, a fuel outlet connection 36, and the accumulator 8. The housing 31 is formed of a first housing 310 and a second housing 320 which are pressed with a metal member and then combined with each other. The first housing 310 is formed by subjecting the joining plate to a deep drawing process, and has a mounting hole 31 at the center formed at one end.
1 and a small-diameter cylindrical portion 313 formed vertically and continuously from the periphery of the wall 312 toward the other end.
And a middle-diameter tube portion 314 and a large-diameter tube portion 315.

The small-diameter cylindrical portion 313 forms an outlet portion 313a communicating with the fuel supply pipe 4 through a screw hole 360 of a fuel outlet side connection portion 36 described later. The medium-diameter cylindrical portion 314 forms an accommodating portion 314 a having a size capable of accommodating the filter paper 32 and a peripheral wall holding the outer periphery of the filter paper 32. Filter paper 32
Is formed with a center hole 32a, and is fixed so that the center hole 32a is in close contact with the outer peripheral portion 330 of the element 33. The element 33 is divided by the wall portion 333 into an opening 331 opened to the fuel supply pipe 2 through a screw hole 352 of the fuel inlet side connection portion 35 described later, and a housing portion 332 for housing the accumulator 8. Stopper 34
Holds the accumulator 8 inside the housing portion 332.

The large-diameter cylindrical portion 315 stores the filter paper 32 in the accommodation portion 31.
An opening 316 serving as an inlet for accommodating the housing 4a, and a first connecting portion 317 formed on the outer peripheral side of the opening 316 and wound around and connected to a second connecting portion 321 of a second housing 320 described later. Have. Second housing 320
Is a lid member to be attached to the first connection portion 317 of the first housing 310 in a state where the filter paper 32 is stored in the storage portion 314a.

The second housing 320 faces the wall 312 of the first housing 310, and has a mounting hole 32 at the center.
1 and a second connection portion 321 formed on the periphery of the wall portion 322 and wound around and connected to the first connection portion 317 of the first housing 310.
The fuel inlet side connection portion 35 has a nut shape made of all genus, and has a through hole 351 opening at a center position on one end side and a screw hole communicating with the through hole 351 on its axis and opening on the other end side. 352 and a small-diameter mounting portion 353 formed on the outer periphery on one end side.

The fuel inlet side connection portion 35 is welded in a state where the mounting portion 353 is inserted into the mounting hole 330 of the second housing 320 and is integrated with the second housing 320. An unillustrated mounting screw member for connecting the fuel supply pipe 2 is screwed into the screw hole 352. The fuel outlet side connection part 36 is a joint nut-shaped one, and has a screw hole 360 communicating with the outlet part 313a of the small diameter cylindrical part 313.
With. The fuel outlet side connection portion 36 is welded to be integrated with the first housing 310 while being inserted into the mounting hole 311 of the first housing 310. A screw member (not shown) for connecting the fuel supply pipe 4 is screwed into the screw hole 360.

The accumulator 8 held by the stopper 34 inside the accommodating portion 332 of the element 33 includes a bellows-shaped metal bellows 83, a metal partition plate 81, and a metal bottom member 84. A sealed gas 82 is sealed in a space surrounded by 83, a partition plate 81 and a bottom member 84. The partition plate 81 is concentrically opposed to the fuel outlet side connection portion 36. Metal bellows 83 and partition plate 8
1 indicates that the metal bellows 83 can be made to have a bellows-like shape, so that the position can be changed left and right in FIG. The bottom 84 is in close contact with the fuel outlet side of the wall 333.

The fuel filter 3 constructed as described above
Is used between the low pressure pump 1 and the high pressure pump 5 and connected to the fuel supply pipes 2 and 4. The fuel filter 3 has a configuration in which the accumulator 8 for reducing the pressure fluctuation of the fuel is accommodated in the accommodation section 332 of the element 33. For this reason, the fuel filter 3 includes an accumulator 8
, Which contributes to simplification of the fuel supply system. The fuel pumped from the fuel tank 6 by the low-pressure pump 1 and supplied to the high-pressure pump 5 is introduced into the housing 31 from the fuel inlet side connection portion 35 of the fuel filter 3 via the fuel supply pipe 2.

After this fuel is purified by the filter paper 32, it is introduced into the outlet 313a, and the fuel outlet side connection 36
Flows into the fuel supply pipe 4 through the screw hole 360, and is supplied to the high-pressure pump 5. The fuel not sent from the high-pressure pump 5 to the accumulator 7 is returned to the fuel supply pipe 4. At this time, pressure fluctuation occurs in the fuel, and this pressure fluctuation is transmitted to the accumulator 8 from the fuel outlet side connection portion 36 of the fuel filter 3 via the fuel supply pipe 4.

The fuel pressure fluctuation acts on the partition plate 81 and the metal bellows 83 according to the magnitude of the fluctuation. Then, the partition plate 81 and the metal bellows 83 attenuate the pressure fluctuation due to the position fluctuation. That is, the partition plate 81 and the metal bellows 83 are displaced in accordance with the magnitude of the pressure fluctuation of the fuel, and absorb and attenuate the pressure fluctuation by changing the volume of the sealed gas 82. As shown in FIG. 3, by incorporating the accumulator 8 in the fuel filter 3, the pressure fluctuation of the fuel is significantly reduced as compared with the case where the accumulator 8 is not incorporated in the fuel filter 3.

In this embodiment, the high-pressure pump 5 is provided by incorporating the accumulator 8 in the fuel filter 3.
Pressure fluctuation of the fuel transmitted to the fuel filter 3 can be reduced. Therefore, the durability of the members inside the low-pressure pump 1, the fuel supply pipe 2, the fuel filter 3, and the like can be ensured. The accumulator 8 is
Since the sealed gas 82 is sealed in the space surrounded by the partition plate 81, the metal bellows 83, and the bottom member 84, higher durability is secured as compared with a pulsation damper having a rubber diaphragm. Further, since the fuel filter 3 has the built-in accumulator 8, the number of parts of the fuel supply system can be reduced. Therefore, the fuel supply system can be easily assembled, and the number of assembling steps can be reduced.

In the present invention, the housing of the fuel filter may be made of resin. Further, the accumulator may be provided separately from the fuel filter, the fuel filter may be built in the fuel tank, and the accumulator may be provided in a fuel supply pipe between the fuel filter and the high-pressure pump.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a fuel filter of a fuel pressure fluctuation reducing device for an internal combustion engine according to one embodiment of the present invention.

FIG. 2 is a schematic configuration diagram showing a fuel supply system using a fuel pressure fluctuation reducing device for an internal combustion engine in the present embodiment.

FIG. 3 is a data diagram showing a fuel pressure fluctuation reducing effect when the fuel pressure fluctuation reducing device for an internal combustion engine in this embodiment is used.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Low-pressure pump 2 Fuel supply pipe 3 Fuel filter 4 Fuel supply pipe 5 High-pressure pump 6 Fuel tank 8 Accumulator 31 Housing 32 Filter paper 33 Element 34 Stopper 35 Fuel inlet side connection part 36 Fuel outlet side connection part 81 Partition plate 82 Filled gas 83 Metal Bellows 84 Bottom member

Claims (3)

[Claims] 1. A fuel pressure fluctuation reducing device comprising: a low-pressure pump; and a high-pressure pump that pressurizes fuel supplied from the low-pressure pump and pumps the fuel to an internal combustion engine. An accumulator that responds to fuel pressure is provided in a fuel supply path between the fuel pressure fluctuations. 2. The fuel pressure fluctuation according to claim 1, wherein the accumulator has a metal bellows and a partition plate, and gas is sealed in a space formed by the metal bellows and the partition plate. Reduction device. 3. The fuel pressure according to claim 1, wherein a fuel filter is provided in a fuel supply path between the low-pressure pump and the high-pressure pump, and the accumulator is built in the fuel filter. Fluctuation reduction device.