JP2002089402A - Pressure fluctuation reducing structure in fuel passage - Google Patents

Abstract

PROBLEM TO BE SOLVED: To further effectively suppress propagation of fuel compression waves outward a delivery pipe, reduce the fuel pulsation sound more than ever, and easily provide them by suppressing the increase in the number of component items as much as possible. SOLUTION: A pulsative insulation space S is formed inside the delivery pipe 5. The insulation space S is formed by inserting a folding-screen shaped member 11 having orifices H alternately vertically into the delivery pipe 5. The adjoining orifices H are prevented from stacking with each other and one orifice H is stacked with a wall part of the member 11 in the passage axial direction. The openings areas of the orifices adjacent to fuel injection valve connecting positions c1-c4 out of the orifices are set relatively large.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure for reducing pressure fluctuations in a fuel passage, and more particularly, to more effectively prevent a fuel compression wave generated by an injection operation of a fuel injection valve from propagating outside a delivery pipe. Related to technology for blocking.

[0002]

2. Description of the Related Art In general, an engine fuel supply system includes:
It comprises a fuel tank, a pump, a fuel supply pipe (centralized pipe), a delivery pipe, a fuel injection valve, a pressure regulating valve, a fuel return passage, and the like. In the above-described fuel supply system, fuel pumped from a fuel tank by a pump passes through a filter, passes through a fuel supply pipe, passes through a fuel hose in an engine room, and is supplied to a delivery pipe connected to a fuel injection valve.

[0003] Among the components of the fuel supply system, those that include a drive unit transmit vibration to the fuel in accordance with the operation thereof. In particular, a needle valve is provided inside such as a fuel injection valve. When the fuel passage has a structure for intermittently opening and closing the fuel passage, remarkable pressure fluctuation is applied to the fuel in accordance with the opening and closing operation. The pressure fluctuation generated in this way propagates as a compression wave of the fuel, causing an oscillating fluctuation in the fuel pressure in the delivery pipe (hereinafter referred to as “fuel pressure”), and further to the fuel hose and the fuel supply pipe. It propagates while being partially attenuated.

[0004] Here, since the fuel supply pipe is generally installed under the vehicle body, the compression wave propagating inside the fuel supply pipe is generated as a sound radiated from the pipe and a bracket or the like for fixing the pipe. Transmitted to the passenger compartment through the vehicle and is recognized as a pulsating sound of the fuel. This pulsating sound is one of the causes of noise including unpleasant frequency components. As a technique for suppressing the propagation of compression waves generated by fuel injection operation,
A vibration damping structure, that is, a pulsation damper installed outside a delivery pipe is known (JP-A-11-72057 and JP-A-8-20017).
No. 8).

[0005]

However, the above conventional technique has the following two problems. The first problem is
Related to the structure of the pulsation damper. In principle, the pulsation damper is intended to suppress the propagation of the compression wave to the outside by freely increasing or decreasing the volume of the fuel chamber provided therein in accordance with the fuel pressure fluctuation. Here, the vibration energy given to the fuel by the fuel injection operation tends to generate a compressional wave of a specific frequency, which generates a fuel pressure fluctuation recognized as a pulsating sound.
According to the above-mentioned conventional structure principle, although the effect of attenuating the amplitude of the fuel pressure fluctuation can be obtained, it does not have the effect of changing the fundamental frequency of the fuel pressure fluctuation which causes the pulsation noise.

The second problem is costly. The pulsation damper is specially added to the fuel supply system in order to suppress fluctuations in fuel pressure, so that the number of parts and the number of joints increase accordingly, and the cost increases. In view of this situation, the present invention provides a pressure fluctuation reduction structure that suppresses the propagation of fuel compression waves in the fuel passage more effectively and with a simple configuration, thereby further reducing the noise in the vehicle interior. It is another object of the present invention to reduce the number of parts as much as possible.

[0007]

SUMMARY OF THE INVENTION Therefore, a pressure fluctuation reducing structure in a fuel passage according to the present invention provides a fuel escape to at least one of a fuel passage upstream and a downstream with respect to a source of a fuel compression wave. A plurality of passage crossing walls forming a port are arranged so that a fuel release port of one adjacent passage crossing wall overlaps a wall portion of the other passage crossing wall in the passage axial direction, and the adjacent passage crossing walls are arranged. A wave-like insulating space is formed between them (claim 1).

Preferably, the fuel outlet is an orifice. Further, it is preferable that the source of the fuel compression wave is a fuel injection valve (claim 3). The insulating space is preferably formed in a delivery pipe for distributing fuel to the fuel injection valve (Claim 4), and is preferably formed from an inlet to an outlet of the delivery pipe (Claim 4). 5).

[0009] The opening area of the fuel outlet near the connection between the fuel injection valve and the delivery pipe is:
It is preferable that the fuel outlet is made larger than the other fuel outlets. It is preferable that the fuel outlets are formed alternately at both symmetrical ends of the passage crossing wall.

[0010] It is preferable that the passage crossing wall is formed by bending a rectangular sheet material lacking a predetermined portion. The passage crossing wall is preferably inclined with respect to a passage vertical cross section (claim 9). The passage crossing wall is preferably continuous in a folding screen shape.
0).

[0011]

According to the first aspect of the present invention, the following effects can be obtained. As described above, the vibration energy given to the fuel from the source of the fuel compression wave easily generates a compression wave of a specific frequency. Here, according to the present invention, a plurality of passage crossing walls are arranged in at least one of the fuel passages on the upstream side and the downstream side of the generation source, and a wave-like insulating space is formed between adjacent ones. At least a part of the fuel compression wave entering the insulating space from the fuel escape port is reflected and scattered by the passage crossing wall on the downstream side in the wave propagation direction. Then, the fuel compression wave that propagates through the fuel passage can be decomposed into a complex vibration component having a lower peak and attenuated, and the generation of the compression wave having the specific frequency can be prevented.

According to the second aspect of the present invention, the above-described effect can be obtained by suppressing the flow path resistance. According to the third aspect of the invention, it is possible to effectively prevent the generation of fuel pulsation noise. According to the invention as set forth in claim 4, the propagation of the fuel compression wave generated by the fuel injection operation to the outside of the delivery pipe, for example, the propagation to the fuel supply pipe under the vehicle body can be easily performed without adding a special component. Can be suppressed.

According to the fifth aspect of the present invention, the fuel compression wave that propagates in the delivery pipe can be decomposed into a vibration component having a lower peak, so that the pressure fluctuation peak in the delivery pipe becomes lower. In addition, uneven distribution of fuel to each fuel injection valve can be prevented. According to the invention according to claim 6, it is possible to prevent a sudden negative pressure from being generated near the fuel injection valve connection portion during fuel injection, and to suppress a pressure fluctuation in the delivery pipe.

According to the seventh aspect of the invention, the linear arrangement of the fuel escape port can be avoided, and the linear propagation of the fuel compression wave in the insulating space can be prevented. Can be enhanced. According to the invention of claim 8, since the passage crossing wall can be formed from one sheet material, the manufacturing cost can be reduced.

According to the ninth aspect of the present invention, since the velocity component toward the flow path side wall can be remarkably given to the fuel compression wave reflected by the passage crossing wall, the fuel compression wave is effectively applied to the insulating space. And the effect of attenuating fuel compression waves can be enhanced. According to the tenth aspect, the passage crossing wall can be easily provided.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 schematically shows a configuration of a fuel supply system of an internal combustion engine according to one embodiment of the present invention. In this fuel supply system, fuel stored in a fuel tank 1 is pumped through a fuel supply pipe 3 under a vehicle body by a pump 2 and is delivered to a fuel delivery pipe (hereinafter referred to as a “delivery pipe”) through a fuel hose 4 in an engine room. 5). Fuel injection valves 6 corresponding to the number of cylinders are connected to the delivery pipe 5, and the injection ports of the fuel injection valves 6 are arranged in intake ports formed in the corresponding cylinders. The fuel in the delivery pipe 5 is injected into each cylinder by the operation of the fuel injection valve 6.

The fuel pressure in the delivery pipe 5 is regulated to a predetermined pressure by a pressure regulating valve 7 connected to the tip (downstream end) of the delivery pipe 5, and excess fuel is supplied to the fuel tank 1 through a fuel return passage 8. Will be returned. Here, a fuel supply pipe 3, a fuel hose 4, a delivery pipe 5
The fuel passage is constituted mainly by the fuel return passage 8.

The fuel injection valve 6 has a built-in electromagnetically driven needle valve and is controlled by an electronic control unit (not shown). When the driving device inputs an injection command (injection pulse width signal) from the electronic control unit and the driving device drives the needle valve based on the command, the injection port is opened and closed according to this movement, and the injection pulse width signal is output. Is supplied with a predetermined amount of fuel. Then, according to the opening and closing of the injection port, the fuel pressure in the vicinity of the connection between the delivery pipe 5 and the fuel injection valve 6 fluctuates oscillating, and this pressure fluctuation becomes a fuel compression wave and propagates through the fuel passage. Therefore, the fuel injection valve 6 forms the source of the fuel compression wave in the present embodiment.

FIG. 2 shows the overall structure of the delivery pipe 5. In addition, the lower figure is a front view of the delivery pipe 5 in which the fuel injection valve 6 can be connected to predetermined connection positions c1 to c4, and the upper figure is a vv cross-sectional view thereof. The delivery pipe 5 may be the same as a conventionally used one having a square cross section (square pipe). Inside the delivery pipe 5, from the inlet 5 i to the outlet 5 e of the delivery pipe 5, the present invention is applied. A plurality of such insulating spaces S are continuously formed.

In the present embodiment, the insulating space S is formed by a continuous orifice forming member (hereinafter, referred to as a “member”) that is integrated into a folding screen.
That. ) 11. The member 11 is
The plurality of thin plates 11a and 11b that are fixed to the delivery pipe 5 and constitute a folding screen are symmetrically oriented, and obliquely cross the internal space of the delivery pipe 5 with respect to a vertical cross section thereof. A triangular prism-shaped insulating space S is formed. Therefore, the thin plates 11a and 11b constitute the passage crossing wall according to the present invention.

FIG. 3 shows a main body 51 of the delivery pipe 5.
In detail. The upper figure is a plan sectional view of the main body 51 viewed from above, and the lower figure is a side sectional view of the main body 51 viewed from the side. The internal space of the delivery pipe 5 is a quadrangular prism having one side dimension w, and four branch passages to the respective fuel injection valves 6 are formed at connection positions c1 to c4. The connection positions c1 to c4 are set at equal intervals with a distance (bore pitch) B therebetween.

The member 11 is installed in such an internal space, and both ends thereof are joined to the inner wall surface of the main body 51 with a joining margin J at an inlet 5i and an outlet 5e of the delivery pipe. The member 11 divides the internal space of the delivery pipe 5 through the thin plates 11a and 11b into an inlet space I upstream of the connection position c1, an outlet space E downstream of the connection position c4, and a connection position c1.
To c4 are divided into 28 insulating spaces S. These insulating spaces S all have the same volume because the thin plates 11a and 11b are symmetrically inclined, and the same number (9 sheets) is provided between adjacent connection positions (for example, c1 and c2). ) Are disposed, and the connection positions c1 to c4 correspond to the bending positions of the member 11.

The spaces I, E,
S communicate with each other via an orifice H formed by the thin plates 11a and 11b. Here, the orifice H is
The orifice h and the orifice h 'are configured as follows. That is, a total of 29 thin plates 11a and 1
1b, eight (2 × 4) thin plates 11a ′ and 11b ′ located at the connection positions c1 to c4 are on the same side (the branch passage side to the fuel injection valve 6, here the lower side in FIG. 3 lower). ), An orifice h ′ is formed, and the other 21 thin plates form orifices h ′ alternately one by one. As a result, the orifices H are formed alternately up and down over the entire internal space of the delivery pipe 5.

As will be described later, the orifice H constitutes a fuel escape port according to the present invention, and has connection positions c1 to c4.
The opening areas (that is, the heights of the orifices) of the eight orifices h are set larger than those of the other orifices h ′. Next, the operation and effect of providing the insulating space S as described above in the delivery pipe 5 will be described.

FIG. 4 is a view for explaining this, in which a part S1 to S6 of the 28 insulating spaces S are enlarged and shown, and an attenuation effect due to reflection and scattering of the fuel flow and the fuel compression wave is shown. This is shown conceptually. As described above, the fuel injection valve 6 is a source of the compressional wave of the fuel, and gives an oscillating pressure fluctuation to the nearby fuel with the injection operation. Fuel compression waves of a frequency are likely to occur.

Here, if the insulating space S is formed according to the present invention, the pressure fluctuation wave propagating in the delivery pipe 5, that is, the fuel compression / decompression wave can be decomposed and attenuated into a complex vibration component having a lower peak. This not only contributes to the reduction of fuel pulsation noise by preventing the generation of the fuel compression wave of the specific frequency, but also makes the fuel pressure in the delivery pipe 5 uniform, so The fuel distribution can be prevented.

Next, this effect will be described in detail with reference to FIG. First, the fuel flowing in the delivery pipe 5 sequentially passes through orifices H1 to H5 formed alternately up and down as shown by the curved arrow F in the figure, and flows to the fuel passage on the further downstream side. Therefore, fuel is supplied to any of the fuel injection valves 6 connected to the connection positions c1 to c4 without any problem.

On the other hand, the pressure fluctuation wave generated at the time of fuel injection (the progress of the wave is indicated by straight arrows P1 to P5 for conceptually and simply understanding) is indicated by the connection position c1 of the fuel injection valve 6. To c4 (c3 is illustrated in the figure), and propagates in the delivery pipe 5 to the upstream side and the downstream side. Here, as a representative example, the waves P3 to P5 propagating to the downstream side will be described.
Is reflected and scattered by the thin plate 11b located immediately downstream. At this time, since the thin plate 11b is inclined with respect to the vertical section of the passage, the reflected wave is remarkably given a velocity component toward the side wall surface of the delivery pipe 5, and is scattered in a complicated manner, and is reflected on the insulating space S4. Effectively confined.
As a result, the trapped waves interfere and attenuate in the insulating space S4.

By the way, since the orifice H4 is formed in the insulating space S4 as a fuel outlet, there may be a wave P5 that passes through the orifice H4 and enters the insulating space S5 that continues downstream. However, the orifice H5 of the downstream thin plate 11a forming the insulating space S5 is connected to the orifice H5 on the inlet side.
4 is symmetrically formed at the lower portion, so that most of the entering waves are reflected and scattered by the thin plate 11a in the same manner as described above, and are also attenuated here.

Due to the repetition of such a damping action, the pressure fluctuation wave generated during the fuel injection operation is broken down into a complicated wave having a lower peak each time it passes through the insulating space S, and is gradually attenuated. Generation of fuel compression waves of a specific frequency is prevented, and the outside of the delivery pipe 5 (for example, the fuel supply pipe 3) can be vibrated insulated from the fuel injection valve 6 as a vibration source.

The connection positions c1 to c4 of the fuel injection valve 6
Since the opening area of the orifice H is larger than that of the other orifices H, the generation of a sudden negative pressure at the time of fuel injection is prevented, and the generation of pressure fluctuation itself is reduced. As described above, in the present embodiment, the insulating space S is formed by the member 11 in which the thin plates 11a and 11b are integrally connected in a folding screen shape, and this member 11 is easily provided from one sheet material. be able to.

FIG. 5 shows that a predetermined portion of a rectangular sheet material having a width w and a length L (L = 29A + 2J, where A is a width of a notch described later; J is a joint allowance of the member 11). Represents a material of the member 11 having a notch N having a width A (= √ ((B / 9) ² + w ² )) and a depth t. Here, since the notch N forms the orifice H when it is arranged in the fuel passage, the notch N is large at the connection positions c1 to c4 of the fuel injection valve 6 and at other positions. In order to make them different, the width of the former is set to t1, and the width of the latter is set to t2 (> t1).

Here, a preferred example of each dimension will be described.
B = 112 [mm], w = 10.5 [mm], t1 = 2
[Mm] and t2 = 4 [mm]. The material thus constructed is bent perpendicularly to the axial direction and alternately in the X direction and the Y direction in the drawing in the opposite direction to obtain a folding screen-shaped member 11. For example, a valley fold is performed in each X section, and a mountain fold is performed in each Y section. Then, if the obtained member 11 is inserted into an existing delivery pipe and fixed at the joint, the delivery pipe 5 having the pressure fluctuation reducing structure according to the present invention can be easily embodied.

[Brief description of the drawings]

FIG. 1 is a diagram schematically illustrating a configuration of a fuel supply system of an internal combustion engine according to an embodiment of the present invention.

FIG. 2 is a diagram showing an overall configuration of a delivery pipe according to the embodiment.

FIG. 3 is a diagram showing details of a main body of the delivery pipe;

FIG. 4 is a diagram conceptually showing a damping effect of a fuel compression wave in an insulating space according to the present invention.

FIG. 5 is a diagram showing a state before bending of a continuous orifice forming member.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Fuel tank 2 ... Pump 3 ... Fuel supply pipe 4 ... Fuel hose 5 ... Delivery pipe 6 ... Fuel injection valve 7 ... Pressure regulating valve 8 ... Fuel return passage c ... Fuel injection valve connection position S ... Insulation space H ... Fuel escape port (Orifice) F… Flow of fuel P… Progress of fuel compression wave

Claims (10)

[Claims] A plurality of passage cross-section walls forming a fuel escape port are provided in at least one of the fuel passages on the upstream side and the downstream side with respect to the source of the fuel compression wave. A pressure fluctuation in the fuel passage, wherein the relief opening is arranged so as to overlap the wall of the other passage transverse wall in the axial direction of the passage, and a wavy insulating space is formed between the adjacent passage transverse walls. Reduction structure. 2. The structure according to claim 1, wherein the fuel outlet is an orifice. 3. The structure according to claim 1, wherein the source of the compressional wave is a fuel injection valve. 4. The structure according to claim 3, wherein the insulating space is formed in a delivery pipe for distributing fuel to the fuel injection valve. 5. The structure according to claim 4, wherein the insulating space is formed from an inlet to an outlet of the delivery pipe. 6. An opening area of the fuel release port near a connection portion between the fuel injection valve and the delivery pipe,
6. The structure for reducing pressure fluctuation in a fuel passage according to claim 4, wherein the other structure is larger than the other fuel outlets. 7. The fuel passage pressure reduction according to claim 1, wherein the fuel outlets are formed alternately at symmetrical ends of the passage crossing wall. Construction. 8. The passage crossing wall according to claim 1, wherein one of the rectangular sheet materials is formed by bending a rectangular sheet material lacking a predetermined portion. Pressure fluctuation reduction structure of fuel passage. 9. The structure for reducing pressure fluctuation in a fuel passage according to claim 1, wherein the passage crossing wall is inclined with respect to a vertical cross section of the passage. 10. The structure for reducing pressure fluctuation in a fuel passage according to claim 9, wherein the passage crossing wall is formed in a screen shape.