JPH02223665A - Fuel injection device - Google Patents

Abstract

PURPOSE:To reduce the number parts and to reduce the number of mounting processes by a method wherein a function serving as a fuel damper to prevent the occurrence of injection pulsation is provided by a filter cover, mounted in a fuel filter, and the opening part of an inflow pipe. CONSTITUTION:A filter cover 35 is mounted on the inflow pipe 36 side of a filter element 34. A spring 38 is positioned in the filter element 34, and resiliently situated between the filter cover 35 and an outflow pipe 37. Injection pulsation due to operation of a fuel injection valve is prevented from occurring in a way that the filter cover 35 approaches and separates away from an opening part 36C of the inflow pipe 36 according to a fuel pressure exerted on the filter cover 35. This constitution enables reduction of the size of a device through decrease of the number of parts, and enables improvement of mounting workability and reduction of a cost.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a fuel injection device that suppresses injection pulsation within a supply pipe when fuel is injected by a fuel injection valve.
In particular, the present invention relates to a fuel injection device suitable for use in high displacement internal combustion engines.

[Conventional technology]

Generally, a fuel injection device is constructed as shown in FIGS. 2 and 3.

In the figure, 1 is an engine, and the engine 1 is mainly composed of a cylinder IA, a piston IB, a combustion chamber IC, and the like. The engine 1 is provided with an intake manifold 2 that takes in outside air into the combustion chamber IC, and the tip side of each branch pipe 2B of the intake manifold 2 directs fuel into the combustion chamber IC. A fuel injection valve 3 for injecting fuel is provided, and a throttle valve 4 is provided upstream of the collector 2A of the intique manifold 2.

Reference numeral 5 indicates a fuel tank that accommodates the fuel A; 6 indicates a fuel pump that is supported by a bracket 7 and is located within the fuel tank 5 and pressure-feeds the fuel A to the fuel injection valve 3; A supply pipe 8 is connected to the fuel pump 6, and the other end of the supply pipe 8 is connected to a pressure regulator 9 that maintains the fuel pressure in the supply pipe 8 constant. 1
Reference numeral 0 denotes a fuel filter that filters out foreign matter from the fuel A pumped by the fuel pump 6, and the fuel filter 10 is provided midway through the supply pipe 8.

In the supply pipe 8, between the pressure regulator 9 and the fuel filter 10, the fuel injection valves 3 are connected in a number corresponding to the number of cylinders of the engine (only one is shown in FIG. 2). do).

Reference numeral 11 denotes a control pressure introduction pipe that introduces a change in negative pressure within the intake manifold 2 caused by a change in the opening degree of the throttle valve 4 as a control pressure. Manifold 2
The collector 2A is connected to the collector 2A. By introducing control pressure into the pressure regulator 9 via the introduction pipe 11, the fuel pressure supplied to each fuel injection valve 3 is controlled to a predetermined set pressure according to the operating condition of the engine 1. .

Reference numeral 12 denotes a return pipe for returning excess oil of the fuel A supplied from the fuel pump 6 to the fuel tank 1 side. One end side of the return pipe 12 is connected to the pressure regulator 9, and the other end side is connected to the fuel tank 5. It is expanding inward.

A fuel damper 13 is installed between the pressure regulator 9 and the fuel filter 10 in the supply pipe 8, and the fuel damper 13 is installed in the fuel injection valve 3 as the displacement of the engine 1 becomes larger. This is provided to suppress the pulsation of fuel pressure (hereinafter referred to as "injection pulsation") that occurs in the supply pipe 8 due to an increase in the injection amount of fuel A injected at one time. The fuel damper 1
3, as shown in FIG. 3, a housing body 14 having a flange portion 14A on the upper side, and a diaphragm 15 placed on the upper surface of the flange portion 14A of the housing body 14.
and a flange portion 14 of the housing body 14. It is generally composed of a lid body 16 that is closed from above and supports the diaphragm 15 in a sandwiched manner. Further, the housing body 14 includes an upstream discharge pipe 17 to which the upstream pipe 8A of the supply pipe 8 is connected, and a downstream pipe 8
A downstream discharge pipe 18 to which B is connected is provided.

The upstream discharge pipe 17 is provided extending from the outside into the lower space LJB defined by the housing body 14 and the diaphragm 15, and is formed by being bent upward at the center of the lower space 14B. An opening 17A at its upper end opens upward. The downstream discharge pipe 18 is integrally protruded from the peripheral wall of the housing body 14 and communicates with the lower space 14B.

A valve body 19 is integrally attached to the center of the diaphragm 15, and the valve body 19 comes into contact with the opening 17A of the upstream discharge pipe 17 to adjust the opening degree of the opening 17A. It looks like this.

Reference numeral 20 denotes a spring provided in the upper space 16A defined by the diaphragm 15 and the lid 16. The spring 20 is elastically installed between the valve body 19 and the lid 16, and is pressed against the opening 17A.

16B is an upper discharge pipe integrally formed on the upper side of the lid 16 and communicated with the upper space 16A, and the upper discharge pipe 16B
is connected to the intique manifold 2 via a connecting pipe 21.

The fuel injection device according to the prior art has the above-mentioned configuration, and its operation will be explained next.

First, the fuel pump 6 rotates due to the starting operation of the engine 1, and the fuel A in the fuel tank 5 is pumped into the supply pipe 8. The pressure of the fuel A fed into the supply pipe 8 is adjusted by a pressure regulator 9, and excess oil is sequentially returned into the fuel tank 5 via a return pipe 12. Then, a predetermined amount of the fuel A in the supply pipe 8, which has been adjusted to a constant pressure, is transferred from the fuel injection valve 3 to the combustion chamber I based on an injection pulse signal from a control unit (not shown).
After being injected to the C side and combusted in the combustion chamber 1C, it becomes exhaust gas and is exhausted from an exhaust manifold (not shown).

On the other hand, if the displacement of the engine 1 is large, the fuel injection valve 3
Since the amount of fuel injected at one time increases, the fuel pressure within the supply pipe 8 immediately after fuel injection also decreases greatly. As a result, as shown in FIG. 4, within the supply pipe 8, injection pulsations in which the fuel pressure continuously changes (reduces) in response to the injection of fuel A from the plurality of fuel injection valves 3 become large. and,
In order to solve this problem, in the fuel damper 13, the diaphragm 15 is bent in accordance with the pressure change according to the injection pulsation, and the valve body 19, which is supported by the diaphragm 15 and pressed by the spring 20, vibrates (moves). ) and adjust the opening degree of the opening 17A of the upstream discharge pipe 17,
Reduces pressure changes due to injection pulsation.

On the other hand, the diaphragm 15 may deteriorate due to deterioration due to long-term use or rapid deformation of the diaphragm 15 due to large changes in injection pulsation within the supply pipe 8.
may be damaged. If the diaphragm 15 is damaged, the fuel A in the lower space 14B will flow into the intique manifold 2 via the upper space 16A, the upper discharge pipe 16B, and the connecting pipe 21, and will flow into the engine room. In addition to preventing fire accidents caused by fuel leaking into the interior, safety is ensured by richness caused by excess fuel.

[Problem that the invention attempts to solve]

However, in the conventional technology with the above structure, since a separate cylinder damper 13 is provided as a means for suppressing pressure pulsations caused by the fuel injection valve 3, the number of parts increases, and
There is a drawback that work is required to install the damper 13 in the middle of the supply pipe 8. Further, even if the diaphragm 15 is damaged, work is required to attach the connecting pipe 21 in order to maintain fail-safe performance, which poses a problem in that the installation workability is poor and the overall cost increases.

The present invention has been made in view of the problems of the prior art described above, and provides a fuel injection device that reduces the number of parts, reduces the size and space, improves installation workability, and reduces costs. The purpose is to

[Means for Solving the Problems] In order to solve the above-mentioned problems, the configuration adopted by the present invention includes a fuel pump that pressure-feeds fuel in a fuel tank, a fuel pump connected to the fuel pump via a supply pipe, A pressure regulator that maintains the fuel pressure in the supply pipe at a constant pressure, a fuel injection valve that injects fuel whose pressure is controlled by the pressure regulator into the internal combustion engine, and a filter that filters foreign matter in the fuel injected from the fuel injection valve. In the fuel injection device, the fuel injection device includes a fuel filter installed in the supply piping for this purpose, and a return piping for returning surplus return oil from the pressure regulator to the fuel tank. a housing provided in the housing, an inflow pipe and an outflow pipe inserted into the housing, and an expandable and retractable cylindrical filter element provided in the housing so as to surround the outflow pipe and filter foreign matter in the fuel. a filter cover provided on the inflow pipe side of the filter element; and a filter cover located within the filter element and resiliently installed between the filter cover and the outflow pipe, the filter cover being provided at the opening of the inflow pipe. The filter cover moves close to and away from the opening of the inflow pipe in response to the fuel pressure acting on the filter cover, thereby suppressing injection pulsation by the fuel injector. be.

[Function] As in the above configuration, since the filter cover biased by the spring and the opening of the inflow pipe have a damper function to suppress injection pulsation, the number of parts can be reduced and the size can be reduced. Installation work becomes easier and costs can be reduced.

〔Example〕

Embodiments of the present invention will be described below with reference to FIG. Note that the overall configuration of the fuel injection device of this embodiment is the same as that of the prior art described above, except for the fuel filter 10 and the fuel damper 13, so a description thereof will be omitted. Note that in this embodiment, a separate fuel damper 13 as in the prior art is not provided.

Reference numeral 30 designates the fuel filter of this embodiment, which is provided in the middle of the supply pipe 8, and the fuel filter 30 has a housing 31 serving as its outer shell, and the housing 31 includes:
The housing main body 32 is provided in the middle of the supply pipe 8 and is formed into a cylindrical shape with a bottom, and the cover body 33 is caulked and fixed to the periphery of the opening of the housing main body 32 to seal the inside.

34 is a filter element provided in the housing 31 to filter foreign matter from the fuel A flowing in the supply pipe 8;
The filter element 34 is formed in a bellows-like and cylindrical shape so that it can expand and contract in the axial direction, and its upper side is attached to the lower surface 33A of the lid body 33.

A filter cover 35 is attached to the lower side of the filter element 34 to partition the inside and outside of the filter element 34, and also functions as a fuel damper in cooperation with an inflow pipe 36, which will be described later. A recess 35A is formed inside the filter element 34 to prevent displacement of a spring 38 (described later) and to receive the dynamic pressure of fuel A flowing out from an inlet pipe 36 (described later).

Reference numeral 36 denotes an inflow pipe attached to the housing body 32 of the housing 31 with a portion protruding into the housing 31, and the external protrusion 36A of the inflow pipe 36 is fitted and connected to the upstream pipe 8C of the supply pipe 8. has been done. Furthermore, the internal protrusion 36B of the inflow pipe 36 is provided with its opening 36C facing the recess 35A of the filter cover 35.

37 is the internal space 34 of the filter element 34 on the inside side.
An outflow pipe made of resin is attached to the lid body 33 in a state of protruding into the inside A, and an external protrusion 37A of the outflow pipe 37 is connected to a downstream pipe 8D of the supply pipe 8. Then, the internal protrusion 3 of the outflow pipe 37 discharged into the internal space 34A
A spring bearing portion 37E is integrally formed at the lower end of the spring bearing portion 7B, the spring bearing portion 37E having a diameter expanding in the radial direction at the opening portion 37C and having an annular convex portion 37D for preventing displacement on the periphery thereof. Note that the external protrusion 37A! , i. The discharge pipe part 33B is fluid-tightly fitted into the discharge pipe part 33B which is discharge-molded in the center of the lid body 33, and the discharge pipe part 33B is fitted and connected to the downstream piping 8D. .

38 is the inner surface 35B of the filter cover 35 and the outflow pipe 37
The spring holder is a spring installed between the part 37E and the part 37E.
The spring 38 is attached to the annular convex portion 37 of the spring bearing portion 37E.
D and the recess 35A of the filter cover 35 to prevent the filter cover 35 from shifting, and urge the filter cover 35 to close the opening 36C of the inflow pipe 36 to set a predetermined valve opening pressure. ing.

The fuel injection device according to this embodiment has the configuration described above, and its operation will be explained next. Note that the operation of the entire fuel injection system is similar to that of the prior art described above, so the explanation thereof will be omitted here.

However, in the fuel filter 30 of this embodiment, the filter cover 35 closes the opening 36C of the inflow pipe 36 by the spring 38 when the fuel pump 6 is not in operation. Next, when the fuel injection device is operated and fuel A is pumped from the fuel pump 6, this fuel A flows from the upstream pipe 8C of the supply pipe 8 into the internal space 31A of the housing 31 via the inflow pipe 36. . At this time, inflow pipe 3
Although the opening 36G of No. 6 is closed by the filter cover 35, it opens against the spring 38 due to the fuel pressure of the fuel A flowing out from the inflow pipe 36. Then, from the inflow pipe 36 to the internal space 31. When the fuel A that has flowed into the interior of A passes through the filter element 34, foreign substances are filtered out, and only the fuel A flows into the internal space 34A of the filter element 34.
flows into. Next, it flows into the outflow pipe 37 through its opening 37C and flows out into the downstream pipe 8D of the supply pipe 8.

When injection pulsation occurs in the supply pipe 8, the flow rate of the fuel A flowing out from the opening 36C of the inflow pipe 36 towards the filter cover 35 changes in accordance with the accompanying change in fuel pressure, and the The pressure difference changes between the internal space 31A and the internal space 34A of the filter element 34. That is, when the fuel A is injected from the fuel injection valve 3 and the pressure suddenly decreases on the downstream side in the supply pipe 8, the pressure on the upstream side increases relatively rapidly, and the opening of the inflow pipe 36 As the flow rate of fuel A flowing out from 36C toward filter cover 35 increases,
The internal pressure of the internal space 31A of the filter element 34 becomes greater than the internal pressure of the internal space 34A of the filter element 34. This results in
Normally, the filter cover 35, which is urged toward the opening 36C by the spring 38 and narrows the flow path, is pushed up against the elastic force of the spring 38, and the filter element 34 contracts, and the opening 36C closes. The flow path area is expanded, a sudden change in fuel pressure within the supply pipe 8 is suppressed, and injection pulsation is reduced.

As described above, in the fuel injection device of this embodiment, the filter cover 35 provided in the fuel filter 30 and biased by the spring 38 and the opening 36C of the inflow pipe 36 act as a fuel damper to suppress injection pulsation. Since this function is provided, a separate fuel damper is no longer required, the number of parts is reduced, the number of installation steps is reduced, workability is improved, and costs can be reduced.

In addition, since the two parts are integrated, it can be made smaller and take up less space, and it can be easily installed in the engine room, where there are many built-in parts and space constraints are increasing. It becomes like this.

Furthermore, since a diaphragm is not used as a means to function as a fuel damper, safety is ensured by reliably preventing fire accidents caused by fuel A leaking into the engine room due to damage to the diaphragm. In addition, it becomes possible to prevent engine stall due to diaphragm damage as in the prior art, and the reliability of the fuel injection device is improved.

In this embodiment, the spring 38 that biases the filter cover 35 is supported by the spring bearing part 37E of the outflow pipe 37, but the spring bearing part 37E is not provided in the outflow pipe 37, and the spring 38 may be directly supported by the lower surface 33A of the lid 33.

Further, the filter element 34 itself may have a structure in which the spring 38 is not specially provided and the filter element 34 itself has elastic force.

〔Effect of the invention〕

As detailed above, according to the present invention, the filter cover provided in the fuel filter and the opening of the inflow pipe function as a fuel damper to suppress injection pulsation, so that a separate fuel damper can be used. This reduces the number of parts, reduces the number of installation steps, improves installation workability, and significantly reduces costs in terms of both parts costs and work costs.

Furthermore, since the two parts are integrated, the parts can be made smaller and occupy less space, and can be easily installed even in an engine room where there are many space constraints.

Furthermore, since engine stalling due to diaphragm damage as in the prior art can be prevented, reliability of the fuel injection device is improved.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view showing a fuel filter according to the present invention, FIGS. 2 to 4 are related to the prior art, FIG. 2 is an overall configuration diagram of a fuel injection device, and FIG. 3 is a vertical cross-sectional view showing a fuel damper. The top view and FIG. 4 are characteristic diagrams showing the relationship between pressure and time in the supply piping in FIG. 2. 3... Fuel injection valve, 5... Fuel tank, 6... Fuel pump, 8... Supply piping, 9... Pressure regulator, 12... Return piping, 30... Fuel filter, 31... Housing, 34... Filter element, 35... Filter cover 36... Inflow pipe, 36C... Opening, 37... Outflow pipe, 37E.
...Spring holder is part, 38...spring.

Claims (1)

[Claims] A fuel pump that pumps fuel in a fuel tank, a pressure regulator that is connected to the fuel pump via a supply pipe and maintains the fuel pressure in the supply pipe at a constant pressure, and a pressure regulator that controls the fuel pressure by the pressure regulator. A fuel injection valve that injects fuel into the internal combustion engine, a fuel filter provided in the supply pipe to filter out foreign matter in the fuel injected from the fuel injection valve, and a fuel filter that drains surplus return oil from the pressure regulator into the fuel tank. In the fuel injection device, the fuel filter includes a housing provided in the middle of the supply pipe, an inflow pipe and an outflow pipe inserted into the housing, and a fuel filter configured to surround the outflow pipe. an expandable and retractable cylindrical filter element provided in the housing to filter foreign matter in the fuel; a filter cover provided on the inlet pipe side of the filter element;
a spring located within the filter element and resiliently installed between the filter cover and the outflow pipe to urge the filter cover to close the opening of the inflow pipe; A fuel injection device characterized in that the filter cover moves close to and away from the opening of the inflow pipe in accordance with the applied fuel pressure, thereby suppressing injection pulsations caused by the fuel injection valve.