JP2002221122A - Fuel delivery pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of vibration and noise due to a reflection wave and a pulsation pressure generated during injection of fuel, in a fuel delivery pipe used in an engine for an electronic control fuel injection type automobile. SOLUTION: A fuel residing space composed of a small partition chamber to absorb the pulsation pressure of fuel is formed in a state to be connected to a seat surface around the periphery of the fuel inflow port of a socket. At least one orifice hole is formed in the wall surface of the small partition chamber and communicated with the internal part of a communication pipe, and the outer shape of the small partition chamber is formed so as to enable a socket receiving hole formed in the communication pipe to pass through. The content volume of the small partition chamber is set to a value larger than the injection amount of a fuel injection nozzle. At least one wall surface of the small partition chamber forms a flexible absorb surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection pump for an electronically controlled fuel injection type automobile engine. The fuel is supplied to each intake passage or each cylinder of the engine through a fuel injection nozzle (injector). The present invention relates to an improvement of a fuel delivery pipe for supplying fuel, and more particularly to a connection structure of a communication pipe having a fuel passage and a socket (holder) part for receiving a fuel injection nozzle.

[0002]

2. Description of the Related Art Fuel delivery pipes are widely used in electronically controlled fuel injection systems of gasoline engines. After fuel is supplied from a communication pipe having a fuel passage to a fuel injector through a plurality of cylindrical sockets. There are a type having a return passage for returning to the fuel tank side and a type having no return passage (returnless). Recently, the number of types without return passages has increased due to cost reduction. However, due to reflected waves and pulsating pressure caused by reciprocating motion of the fuel pump (plunger pump) and injector spool, fuel delivery pipes and related A problem has arisen in that parts vibrate and generate unpleasant noises.

According to the study of the present inventor, it has been found that as the rotational speed of the internal combustion engine increases, the overlap of fuel pressure oscillation due to fuel injection at each socket portion increases, and the generation of abnormal noise is increased. did. This is because (a) when fuel is injected, the pressure in the socket directly connected to the injector drops rapidly. (B) The connection diameter of the socket is smaller than that of the communication pipe, but resistance to pressure propagation occurs. (C) When fuel is injected, the effect of the pressure drop immediately propagates into the communication pipe. (D) Various noises are generated due to the pressure propagation. As a result, it is considered that the pressure drop in the socket is immediately propagated into the communication pipe with the fuel injection, and various problems are caused by the pressure fluctuation in the fuel flow path.

Japanese Patent Application Laid-Open No. H11-2164, "Fuel Delivery", pays attention to this problem, and manufactures a delivery body by a sheet metal press in order to reduce the pulsation resonance speed of the fuel piping system to an idle speed or less. It has been proposed to set the rigidity and the internal capacity of the device within a certain range. However,
In many cases, the body of the fuel delivery pipe is made of a steel pipe having a circular or square cross section, and there are many problems in adopting the above method from the viewpoint of engine specifications, strength, and cost. Japanese Patent Publication No. 3-62904, "Fuel Rail for Internal Combustion Engine", uses a diaphragm to partition the inside of a communicating pipe into a socket side and a pipe wall side in order to prevent injector wrap noise. The residual reaction of the injector is absorbed. However, arranging a flexible diaphragm in the longitudinal direction of the communication pipe requires a sealing member, which complicates the structure, restricts the overall shape, and supports a wide variety of engine specifications. There is a drawback that you can not.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to suppress pressure fluctuations in a fuel flow path due to fuel injection, suppress vibrations caused by reflected waves and pulsating pressure of fuel, and reduce abnormal noise. An object of the present invention is to provide a fuel delivery pipe structure capable of preventing occurrence and various troubles.

[0006]

SUMMARY OF THE INVENTION The first object of the present invention is to provide a communication pipe having a fuel passage extending in a straight line therein and fixed to an end or a side of the communication pipe. A fuel delivery system for an internal combustion engine, comprising: a fuel introduction pipe; and a plurality of sockets inserted into a socket receiving hole of the communication pipe and communicating with the fuel passage and having an open end receiving a tip of a fuel injection nozzle. In the pipe,
A fuel storage space comprising a small compartment for absorbing pulsating pressure of fuel is connected to a seating surface around a fuel inlet of the socket, and at least one orifice hole is formed in a wall surface of the small compartment. To communicate with the inside of the communication pipe,
The external shape of the small compartment is achieved by a fuel delivery pipe formed to be able to pass through the socket receiving hole provided in the communication pipe.

[0007]

According to the fuel delivery pipe of the present invention, by adopting such a structure, the vibration is damped by the resistance when the fuel passes through the orifice hole.
A part of the injection amount by the injection nozzle is temporarily accumulated as a fuel pool in the small chamber and is sequentially discharged, so that the small chamber acts as a damper, suppressing pressure fluctuations in the fuel flow path, and reducing It is possible to prevent generation of abnormal noise due to vibration or pulsation caused by the reflected wave or the damping ability of the communication pipe.

[0008] The outer shape of the small compartment is formed so as to be able to pass through the socket receiving hole of the communication pipe. At the time of manufacture, the socket and the small compartment are integrally formed by brazing or welding and then inserted from the socket receiving hole. The fuel delivery pipe can be easily manufactured. It is desirable that the internal volume of the fuel storage space has an internal volume that is equal to or larger than the fuel injection capacity for one time. It has little effect on reach or speed.

It is desirable that the size of the orifice hole be small enough to allow the previously injected portion to pass between the end of the injection and the next injection. Thus, it is possible to minimize the propagation of the pressure drop in the fuel storage space during injection into the communication pipe. Thus, pressure fluctuations in the fuel flow path are kept low, and various noises are reduced.

The theoretical basis for damping the vibrations by the orifice hole is as follows. When a shock wave generated when the fuel injection nozzle is opened and closed passes through the orifice hole, (a) when the shock wave collides with the small chamber, The chamber bends to absorb impact energy and absorbs fuel pressure fluctuations. (B) The instant the chamber passes through an orifice hole provided in the small chamber, the small chamber bends to absorb impact energy and fuel pressure fluctuations. (C) Absorbs impact energy by bending its direction when entering the inside of the communication pipe through the orifice hole, and absorbs fuel pressure fluctuation. (D) When entering the communication pipe through the orifice hole It is understood that the volume suddenly expands to absorb the impact energy and absorb the fuel pressure fluctuation.

According to the present invention, at least one outer wall surface of the small compartment is constituted by a flexible absorbing surface (damping surface), so that the absorbing surface absorbs impact energy more and enhances a damping effect. It becomes possible. For example, the small compartment is formed in a bellows shape made of a thin steel pipe, or is formed by welding or electroforming a disc spring-like thin plate, and this ribbed shape becomes an absorber surface to absorb impact.

Further, when the shock wave enters the inside of the communication pipe from the orifice hole, the orifice hole may be offset to the left or right or opened to the side in order to increase the damping effect by bending the direction as much as possible. it can. In addition, a large number of baffle plates are interposed inside the small compartment to change the vector direction of the energy propagation by the shock wave in the opposite direction, or to provide a small gap between the wall and the wall to improve the damping effect. desirable.

In the present invention, the shape, plate thickness, length and the like of the small compartment can be determined by experiments and analysis so that the vibration and pulsation are minimized particularly when the engine is idling.

Since the present invention basically relates to the internal structure of the fuel delivery pipe, compatibility with the conventional fuel delivery pipe can be maintained. Other features and advantages of the present invention will become apparent from the following description in which reference is made to the embodiments of the accompanying drawings.

[0015]

FIG. 1 shows a basic overall shape of a fuel delivery pipe (top feed type) 10 according to the present invention, which has a square cross section, a circular cross section, and a communicating pipe formed of another cross section. The pipe 11 extends along the crankshaft direction, and the fuel introduction pipe 2 is fixed to the side of the communication pipe 11 via the connector 5 by brazing or welding.
A return pipe for returning to the fuel tank can be provided at the end of the communication pipe. However, the return pipe is not provided in a returnless type fuel delivery pipe in which pulsation pressure of the fuel is particularly problematic.

In the case of a three-cylinder engine, three sockets 3 for receiving the tip of the injection nozzle are mounted on the bottom surface of the communication pipe 11 at predetermined intervals and angles. Two thick and rigid brackets 4 for attaching the fuel delivery pipe to the engine main body are further laterally bridged over the communication pipe 11. The fuel flows in the direction of the arrow, and is injected from the socket 3 into each intake passage or each cylinder via a fuel injector (not shown).

FIG. 2 is a sectional view of a fuel delivery pipe 20 according to a first embodiment of the present invention.
The fuel passage 21a linearly extends inside the inside. The plurality of sockets 3 have their mounting-side ends inserted into the socket receiving holes 7 of the communication pipe 21 and their open ends receiving the tip of the fuel injection nozzle. According to the present invention, a fuel storage space 23 composed of a small compartment 22 for absorbing pressure fluctuations of fuel is connected to a seating surface 13a around the fuel inlet 13 of each socket 3 in the communication pipe 21. .
The outer shape of the small compartment 22 is formed in a shape that can pass through the socket receiving hole 7 of the communication pipe 21, and in the example of FIG. 2, the small compartment 22 is formed in a pipe shape having a bellows-shaped cross section. Each of the small compartments 22 is provided so that its internal volume is as large as possible, and the orifice hole 25 is drilled at the top thereof. The inside of the small chamber 22 is kept in communication with the inside of the communication pipe 21 via the orifice hole 25.

FIG. 3A is a sectional view of the small compartment in the first embodiment, and shows the positional relationship between the communication tube 21 and the small compartment 22 having a square cross section. The compartment 22 is made entirely of thin-walled steel tubing, and the entire bellows-shaped cross section, preferably the surface 28 of the socket 3 facing the fuel inlet 13, provides a flexible absorbing surface (damping surface). It is made elastically deformable.

Thus, the vibration is damped by the resistance when the fuel passes through the orifice hole 25, and a part of the injection amount of the injection nozzle is temporarily stored in the small compartment 22 as the fuel pool 23 and sequentially stored. By being discharged, the small chamber 22 acts as a damper, suppressing pressure fluctuations in the fuel flow path, and preventing generation of abnormal noise due to vibration or pulsation caused by reflected waves of the injector or damping ability of the communication pipe. You can do it.

Further, the shock wave passing through the fuel inlet 13 immediately after the fuel injection collides with the absorptive surface 28 at the moment when it flows into the small compartment 22, so that the absorptive surface 28 bends at the same time as the small-sized small compartment 22 having the bellows shape. The whole also bends to absorb the impact energy, and the volume expands rapidly when passing through the orifice hole 25 and into the communication pipe 21 and changes its direction to absorb the impact energy and absorb the fuel pressure fluctuation. Will be understood.

FIG. 3B shows a modified example of the communication pipe and the small compartment. The fuel delivery pipe 30 has a communication pipe 31 having a circular cross section and a small compartment 32 having a bellows-shaped cross section accommodated therein. Similarly to the example of FIG. 3A, the orifice hole 35 is provided at the top of the small compartment 32, and the entire wall surface of the absorptive surface 38 and the small compartment 32 is made of a flexible absorbent surface, thereby similarly absorbing the shock. The effect can be enhanced.

FIG. 4 shows another modification of the small compartment.
In the fuel delivery pipe 40, a cylindrical small compartment 42 is housed inside a communication pipe 41 having a square cross section, and a plurality of baffle plates 46 are arranged in a labyrinth (maze) shape inside the small delivery chamber 42. This is because, as described above, when the shock wave passes through the inside of the socket and enters the inside of the communication tube from the orifice hole, the direction of the passage is bent as much as possible and the passage distance is increased to enhance the damping effect. That is, the fuel passes through the small gap 49 between the baffle plate 46 and the wall surface to the orifice hole 45, and the shock wave bypasses the baffle plate 46 while reversing the propagation direction of the energy. Further, the impact absorbing effect is enhanced by passing through the orifice hole 45 having a small diameter. In this example, the small compartment 4
By configuring the entire wall surface 2 or only the top plate 48 with a flexible absorber surface, it is possible to further enhance the shock absorbing effect.

FIGS. 5A and 5B show still another modification. The fuel delivery pipe 50 shows another modification of the small compartment, and a horizontal section is formed inside a communication pipe 51 having a square section. An oval cylindrical small compartment 52 is housed therein. The orifice hole 55 is formed not on the top but on the side face to enhance the damping effect. Also in this example, the shock absorbing effect can be similarly enhanced by configuring the entire wall surface of the small compartment 52 or only the cap 58 with a flexible absorber surface. In this embodiment, the cap 58 is made of a thin metal such as SPCC, SPHC, SU.
S is made from a strip material such as S by plastic working such as drawing, and is fixed to the top of the small compartment 52, thereby facilitating bending to the end portion of the small compartment 52 and increasing the shock absorbing effect. ing.

[0024]

As described above in detail, according to the fuel delivery pipe of the present invention, the vibration is buffered by the resistance when the fuel passes through the orifice hole, and the shock wave detours while passing through a small gap. A shock absorbing effect is exhibited by changing direction after passing through a small diameter orifice, and a part of the injection amount by the injection nozzle is temporarily accumulated as a fuel pool in a small chamber and sequentially discharged, and as a damper It acts to suppress pressure fluctuations in the fuel flow path and to prevent the occurrence of abnormal noise and various problems due to vibrations and pulsations caused by the reflected waves of the injector and the damping ability of the communication pipe. Some of the technical effects are quite significant.

[Brief description of the drawings]

FIG. 1 is a front view showing an entire fuel delivery pipe according to the present invention.

FIG. 2 is a longitudinal sectional view of a first embodiment of the fuel delivery pipe.

FIG. 3 is a sectional view of a socket portion of the fuel delivery pipe of FIG. 2;

FIG. 4 is a longitudinal sectional view of a fuel delivery pipe according to another embodiment.

FIG. 5 is a longitudinal sectional view of a fuel delivery pipe according to another embodiment.

[Explanation of symbols]

2 Fuel introduction pipe 3 Socket 7 Socket receiving hole 10, 20, 30, 40, 50 Fuel delivery pipe 11, 21, 31, 41, 51 Communication pipe 13 Fuel inlet 13a Seating surface 21a Fuel passage 22, 32, 42, 52 Small compartment 25,35,45,55 Orifice hole 46 Baffle plate

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F02M 37/00 321 F02M 37/00 321A

Claims (5)

[Claims] 1. A communication pipe having a fuel passage extending in a straight line therein, a fuel introduction pipe fixed to an end or a side of the communication pipe, and said fuel pipe inserted into a socket receiving hole of said communication pipe. A fuel delivery pipe for an internal combustion engine comprising: a plurality of sockets communicating with the passage and having an open end for receiving a tip of a fuel injection nozzle, wherein a pulsating pressure of fuel is applied to a seating surface around a fuel inlet of the socket. A fuel reservoir space consisting of a small compartment for absorbing the gas is connected and arranged, and at least one orifice hole is formed in a wall surface of the small compartment so as to communicate with the inside of the communication pipe;
A fuel delivery pipe, wherein an outer shape of the small compartment is made to pass through the socket receiving hole provided in the communication pipe. 2. The fuel delivery pipe according to claim 1, wherein an inner volume of the small compartment is set to be larger than a single injection amount of the fuel injection nozzle. 3. The fuel delivery pipe according to claim 1, wherein at least one wall surface of the small compartment is formed of a flexible absorber surface. 4. The fuel delivery pipe according to claim 1, wherein the small compartment is formed in a thin, bellows shape. 5. The fuel delivery pipe according to claim 1, wherein a baffle plate is disposed inside the small compartment.