JP4053340B2 - Fuel delivery pipe - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fuel for supplying fuel fed from a fuel pressurizing pump of an electronic fuel injection type automobile engine via a fuel injector (injection nozzle) for directly injecting the fuel into each intake passage or cylinder of the engine. The present invention relates to the improvement of the delivery pipe, and particularly relates to the cross-sectional structure of the communication pipe having the fuel passage and the external structure of the communication pipe.
[0002]
[Prior art]
Fuel delivery pipes are widely used in electronic fuel injection systems for gasoline engines. After fuel is sent from a communication pipe having a fuel passage to a fuel injector through a plurality of cylindrical sockets, the fuel delivery pipe is moved to the fuel tank side. There are a type having a return path for returning and a type having no return path (returnless). Recently, the type that does not have a return passage has been increasing due to measures to reduce transpiration gas with high-temperature return fuel and cost reduction. Along with this, the reflected wave caused by the reciprocating motion of the spool that opens and closes the valve to inject from the injector The fuel injection pulsation due to (shock wave) and pulsation pressure has caused a problem that the fuel delivery pipe and related parts vibrate and generate an unusual noise. In addition, abnormal noise was also generated due to the impact accompanying the seating of the injector spool.
In a so-called direct injection type engine in which fuel is directly injected into a combustion chamber, a high-pressure supply pump is provided. Therefore, a pulsation damper is provided to absorb the large pulsation, and a normal fuel injection type (MPI) Although it is also used in some cases in the case of engines, it is not easy to adopt due to space constraints and high costs.
[0003]
FIG. 6 shows a conventional example in which part of the box-shaped cross section of the fuel delivery pipes 1 and 2 is made a flexible absorber surface to absorb vibration. In FIG. 6A, the upper surface 85 facing the fuel inlet 13 of the socket 3 connected to the fuel injection valve is made of a thin plate to provide an absorbent surface, and in FIG. 6B , the side surface 86 is made of a thin plate and Providing a plane.
[0004]
FIG. 7 is an enlarged view of the relationship between a conventional socket and an injection nozzle. When the upper surface 11a of the communication pipe 11 is an absorber surface, a fuel supply hole 6a (inner diameter d: normal) provided at the rear end of the injection nozzle 6 is shown. 4-5 mm) is reflected by an abrupt cross-sectional change at the fuel inlet 13 (inner diameter D) provided at the upper end of the recess 3a for receiving the rear end of the injection nozzle in the socket 3. As a result, a standing wave is generated between the injection nozzle 6 and the fuel inlet 13, and the fuel delivery pipe mechanically resonates with the standing wave. In particular, high-frequency noise is transmitted around the fuel delivery pipe. There was a problem that it was transmitted and radiated.
[0005]
Japanese Patent Laid-Open No. 10-331743 “Fuel distribution pipe structure for internal combustion engine” suppresses the generation of large radiated sound due to pulsation by increasing the rigidity of the fuel delivery pipe.
Japanese Patent Application Laid-Open No. 60-240867, “Fuel Supply Pipe for Fuel Injection Device for Internal Combustion Engine” is an elastic so as to attenuate fuel pulsation at least one of the walls of the fuel supply pipe in order to improve the fuel delivery pipe. It is configured.
Similarly, Japanese Patent Application Laid-Open No. 8-326622 “Fuel Pressure Pulsation Damping Device” and Japanese Patent Application Laid-Open No. 11-37380 “Delivery Pipe” also show devices for improving pulsation by improving the fuel delivery pipe.
[0006]
[Problems to be solved by the invention]
The object of the present invention is to reduce the shock wave and pulsation pressure generated by opening and closing the fuel injection nozzle and to reduce the generation, transmission, propagation and radiation of the above-mentioned high frequency noise. It is to provide a new structure.
[0007]
[Means for Solving the Problems]
In order to reduce the above-described noise in the high frequency range, the inventor has to make the inner diameter (D) of the fuel inlet of the socket more than twice the inner diameter (d) of the fuel supply hole at the rear end of the injection nozzle. It was found to be effective, and the effect was confirmed by experiment.
That is, the above-described problem of the present invention is that the outer wall surface facing the socket of the communication pipe is flat or arcuate and includes a flexible absorber surface, and the upper end of the recess that receives the rear end of the injection nozzle inside the socket. This is achieved by a fuel delivery pipe in which the inner diameter (D) of the fuel inlet provided in the fuel inlet is at least twice the inner diameter (d) of the fuel supply hole at the rear end of the injection nozzle.
[0008]
[Action]
When the inner diameter (D) of the fuel inlet provided at the upper end of the recess for receiving the rear end of the injection nozzle in the socket is set to be twice or more the inner diameter (d) of the fuel supply hole at the rear end of the injection nozzle, the fuel of the injection nozzle Noise emitted from the supply hole (inner diameter d) hardly reflects at the socket's fuel inlet (inner diameter D) and propagates through the fuel inlet to the absorber surface as it is. It will be damped by the absorber surface without causing resonance. That is, the noise emitted from the fuel supply hole (inner diameter d) of the injection nozzle does not generate a standing wave in the vicinity of the fuel inlet (inner diameter D) as in the prior art, and passes through the fuel inlet as it is. Therefore, noise in the high frequency range can be prevented from being transmitted / propagated / radiated around the fuel delivery pipe.
Thus, the noise in the high frequency range radiated from the absorber surface of the fuel delivery pipe is reduced, and the pulsation pressure and the shock wave of the fuel flowing into the socket are reduced by the deflection of the absorber surface.
[0009]
As a preferred embodiment, the inner diameter of the socket recess and the inner diameter of the fuel inlet can be made substantially the same. This can also be obtained by cutting the upper end of the socket horizontally or by making the socket into a simple cylinder.
[0010]
The rationale for absorbing pulsation by the absorber surface is that the shock wave generated when the fuel injector is opened and closed flows into the socket's fuel inlet or flows out due to momentary reverse flow. It is understood that shock and pulsation are absorbed by this, and that a thin member having a relatively small spring constant is bent and deformed to change the volume and absorb fuel pressure fluctuations.
[0011]
In the present invention, the thickness of the absorber surface is preferably the same as or less than the thickness of the other surfaces. Further, it is desirable that the radius of curvature of the arc surface constituting the absorber surface is larger than twice the thickness of the absorber surface.
[0012]
In the present invention, the outer wall of the communication pipe, the thickness of the absorber surface, the aspect ratio, the gap between the socket and the surface facing the fuel inlet, etc., have the smallest values of vibration and pulsation especially when the engine is idling. It can be determined by experiment and analysis.
Since the present invention basically relates to the cross-sectional structure of the communication pipe and the external structure of the communication pipe, it is possible to maintain compatibility with the conventional fuel delivery pipe by maintaining the mounting dimensions of the bracket. it can. Other features and advantages of the present invention will become apparent from the following description with reference to the embodiments of the accompanying drawings.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
1A to 1C show a fuel delivery pipe 10 according to a first embodiment of the present invention, FIG. 1A is a perspective view of the whole, and FIG. 1B is a longitudinal sectional view with a part broken along a longitudinal direction of a communication pipe. 1C is a longitudinal sectional view of the socket portion.
For example, in the case of a four-cylinder engine, four sockets 3 are attached to the bottom surface of the communication pipe 11 extending along the crankshaft direction at a predetermined interval and angle. Further, two thick and rigid brackets 4 for attaching the fuel delivery pipe 10 to the engine body are bridged across the communication pipe 11 in the lateral direction. The fuel flows in the direction of the arrow, and is directly injected into each intake passage or cylinder from the injection nozzle at the tip of the socket 3 through the fuel injector 6.
[0014]
The fuel introduction pipe 5 is fixed to the end of the communication pipe 11 having the fuel passage 12 inside by brazing or welding via a connector (not shown). Although a return pipe for returning to the fuel tank can be provided at the end of the communication pipe 11, the return-less fuel delivery pipe is not provided with a return pipe.
[0015]
As shown in FIG. 1C, in this example, the communication pipe 11 has a flat rectangular cross section formed by crushing a pipe made of carbon steel or stainless steel having a circular cross section. The vertical and horizontal dimensions of the communication pipe 11 can be set to, for example, a flat plate having a thickness of 1.2 mm, a height of 6.4 mm, and a width of about 32 mm.
[0016]
According to the feature of the present invention, the upper surface 11a facing the socket mounting surface 11b at the outer wall portion of the communication tube 11 having a flat rectangular cross section provides a flexible absorber surface, and this absorber surface faces the fuel inlet 13 of the socket 3. Therefore, it works to absorb vibration and shock during fuel injection.
Further, according to the feature of the present invention, the inner diameter (D) of the fuel inlet 13 provided at the upper end of the recess 3a for receiving the rear end of the injection nozzle in the socket 3 is the inner diameter (d) of the fuel supply hole 6a at the rear end of the injection nozzle. ) Is more than twice as large.
[0017]
As can be understood from FIG. 1C, since the inner diameter (D) of the fuel inlet 13 of the socket 3 is more than twice the inner diameter (d) of the fuel supply hole 6a at the rear end of the injection nozzle, the fuel of the injection nozzle The elastic wave emitted from the supply hole 6a hardly collides / reflects the wall surface around the fuel inlet 13 of the socket, passes through the fuel inlet 13 without generating a standing wave, and passes through the absorber surface 11a. Propagate to. For this reason, a standing wave is not generated in the socket portion as in the prior art, and the attenuation is caused on the absorber surface. Therefore, it is possible to prevent the noise in the high frequency range from being transmitted, propagated and radiated around the fuel delivery pipe.
Thus, the noise in the high frequency range radiated from the injection nozzle is reduced, and the pulsation pressure and the shock wave of the fuel flowing into the socket are reduced by the bending of the absorber surface 11a.
[0018]
FIG. 2 shows a modification of the socket. A flange-like folded portion 25 is formed on the upper portion of the socket 23 to provide a stopper and a brazing surface. The inner diameter D of the recess 23a of the socket 23 and the inner diameter D of the fuel inlet are approximately the same size, and the injection The nozzle 6 is made to be twice or more the inner diameter d of the fuel supply hole 6a. Providing the folded portion 25 as shown in the figure has an advantage that the socket 23 can be prevented from being inclined from the direction of the central axis during the brazing operation between the socket and the communication pipe.
[0019]
FIG. 3 shows an example in which the upper end of the socket 30 is folded outward to form the flange portion 32, and a hole 11d equal to the inner diameter D of the socket 30 is formed on the side of the socket mounting surface 11b of the communication pipe. The inner diameter D is made twice or more the inner diameter d of the fuel supply hole 6a of the injection nozzle 6. Providing such a flange portion 32 has an advantage that the socket 30 can be prevented from being inclined from the direction of the central axis during the brazing operation between the socket and the communication pipe.
[0020]
FIG. 4 shows an example in which the lower end of the socket 40 is folded outward to form the flange portion 42 and the upper end of the socket 40 is cut horizontally. The inner diameter D of the socket 40 is made twice or more the inner diameter d of the fuel supply hole 6 a of the injection nozzle 6. Forming such a flange portion 42 has an advantage that the socket 40 can be prevented from being inclined from the direction of the central axis during the brazing operation between the socket and the communication pipe.
[0021]
FIGS. 5A and 5B show fuel delivery pipes 60 and 66 according to another embodiment. In FIG. 5A, the upper surface 61a of the communication pipe provides a flexible absorber surface, and the periphery of the socket receiving portion of the socket mounting surface 61b is folded upward to form a guide portion 61d, in which a cylindrical shape is formed. A socket 63 is inserted and brazed. The inner diameter D of the socket 63 is made more than twice the inner diameter d of the fuel supply hole of the injection nozzle. In FIG. 5B, the upper surface 67a of the communication pipe provides a flexible absorber surface, and the periphery of the socket receiving portion of the socket mounting surface 67b is folded downward to form a guide portion 67d, in which a cylindrical shape is formed. A socket 68 is inserted and brazed. The inner diameter D of the socket 68 is made more than twice the inner diameter d of the fuel supply hole of the injection nozzle.
Forming such guide portions 61d and 67d has an advantage that the sockets 63 and 68 can be prevented from being tilted from the direction of the central axis during the brazing operation between the socket and the communication pipe.
[0022]
【The invention's effect】
As described above in detail, according to the present invention, the inner diameter (D) of the fuel inlet is made more than twice the inner diameter (d) of the fuel supply hole at the rear end of the injection nozzle. The elastic wave emitted from the (inner diameter d) does not collide with or reflect on the wall surface around the fuel inlet (inner diameter D) of the socket to generate a standing wave. It propagates to the surface and is attenuated without causing resonance. As a result, noise in the high frequency range radiated from the injection nozzle is reduced, and the pulsation pressure and shock wave of the fuel flowing into the socket are reduced by the deflection of the absorber surface. There is.
[Brief description of the drawings]
FIG. 1 is a perspective view showing the entire fuel delivery pipe according to the present invention and a longitudinal sectional view of a socket portion.
FIG. 2 is a cross-sectional view of a socket portion according to another embodiment.
FIG. 3 is a cross-sectional view of a socket portion according to another embodiment.
FIG. 4 is a cross-sectional view of a socket portion according to another embodiment.
FIG. 5 is a cross-sectional view of a socket portion according to another embodiment.
FIG. 6 is a cross-sectional view of an absorber surface in a conventional delivery pipe.
FIG. 7 is a cross-sectional view of an injection nozzle mounting portion in a conventional delivery pipe.
[Explanation of symbols]
3, 23, 30, 40, 63, 68 Socket 3a, 23a Recess 5 Fuel introduction pipe 6 Injection nozzle 6a Fuel supply hole 10, 60, 66 Fuel delivery pipe 11 Communication pipe 11a, 61a, 67a Absorbing surface 11b, 61b , 67b Socket mounting surface 12 Fuel passage 12b Fuel passage lower surface 13 Fuel inlet D Fuel inlet inner diameter d Fuel supply hole inner diameter

Claims (2)

A communication pipe having a fuel passage extending in a straight line, a fuel introduction pipe fixed to an end portion or a side portion of the communication pipe, a portion projecting across the communication pipe and a part thereof communicating with the fuel passage And a fuel delivery pipe having a plurality of sockets whose open ends receive the rear end of the fuel injection nozzle,
The outer wall surface facing the socket of the communication pipe includes a flat or arcuate flexible absorber surface,
The inner diameter (D) of the fuel inlet provided at the upper end of the recess for receiving the rear end of the injection nozzle in the socket is at least twice the inner diameter (d) of the fuel supply hole at the rear end of the injection nozzle;
This reduces the noise in the high frequency range radiated from the absorber surface of the fuel delivery pipe, and reduces the pulsation pressure and shock wave of the fuel flowing into the socket by bending the absorber surface. Fuel delivery pipe.   The fuel delivery pipe according to claim 1, wherein an inner diameter of the recess of the socket and an inner diameter of the fuel inlet are substantially the same.

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