JP2002061552A - Fuel rail - Google Patents

Abstract

(57) [Summary] [Problem] To have an excellent effect of suppressing a pressure change inside a fuel supply pipe at the time of fuel injection, to have a simple structure and a small number of parts,
Provide highly reliable fuel rails. SOLUTION: In a fuel rail connected to a fuel supply pipe for leading a fuel to an automobile engine and distributing the fuel to an injector, a main body case 16 having a double structure in which an air chamber 22 is airtightly partitioned is provided. A partition 24 that partitions the air chamber 22 is made of a thin metal plate.
Absorbs pressure changes due to deformation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel rail used in a fuel supply system for supplying fuel to an automobile engine, and more particularly to a fuel pressure change generated in a fuel supply pipe when an injector is opened and closed. Regarding the fuel rail that suppresses.

[0002]

2. Description of the Related Art In a fuel supply system of an automobile engine, a fuel rail for distributing fuel to an injector is connected to a fuel supply pipe, and an appropriate amount of fuel is injected from an electronically controlled injector to an intake port of the engine.

[0003] In this type of fuel supply system, when fuel is injected from an injector, the pressure decreases due to a decrease in the fuel volume in the fuel supply pipe, and when the injector is closed, the fuel pressure increases. The pulsation phenomenon in which alternately increases and decreases appears. The pulsation of the fuel is transmitted as vibration to the vehicle body, causing a problem that the fuel pulsation is transmitted from under the floor of the vehicle body into the vehicle as noise. For this reason, various improvements for reducing fuel pulsation have been conventionally proposed.

Conventionally, generally, a damping element such as a pulsation damper or a rubber tube for absorbing a pulsation is connected in the middle of a fuel pipe. Can be cited.

There are also known prior arts of a type in which a pulsation damper is externally attached to a fuel rail and a type in which a pulsation damper is accommodated inside a fuel rail (for example, US Pat.
No. 827).

[0006]

However, the pulsation damper of the type in which the pulsation damper is connected in the middle of the fuel supply pipe is restricted by the piping space due to the piping space on the vehicle body side. It is not inexpensive and requires additional parts for connection to the fuel supply pipe. Further, when a pulsation damping tube made of an elastic member capable of expanding and contracting a passage volume is used as a fuel supply tube as in the prior art of Japanese Utility Model Application Laid-Open No. 62-26561, the function of absorbing a decrease in fuel pressure is a pulsation. Since it is inferior to a damper and has a lower pressure resistance than tubes constituting other fuel supply pipes, there is a problem in reliability.

On the other hand, conventional fuel rails of the type in which a pulsation damper is externally mounted have the disadvantage that the structure is complicated, the number of parts is increased, and the cost is high. Similarly, a structure for fixing the damper and a seal structure are required, and the cost increases.

Accordingly, an object of the present invention is to solve the above-mentioned problems of the prior art, to have an excellent effect of suppressing a pressure change inside a fuel supply pipe during fuel injection, to have a simple structure, to reduce the number of parts, and to improve reliability. To provide a high fuel rail.

[0009]

According to one aspect of the present invention, there is provided a fuel rail which is connected to a fuel supply pipe for leading fuel to an automobile engine and distributes fuel to an injector. It has a main body case of a double structure in which an air chamber is partitioned in an airtight manner, and a partition partitioning the air chamber is made of a thin metal plate.

According to the first aspect of the present invention, when the internal volume of the pipe is reduced at the time of fuel injection and the balance between the pressure in the air chamber and the fuel pressure is lost, the partition wall made of a thin steel plate is pushed by the air pressure. Deform to absorb the decrease in tube volume. Thereby, a pressure change in the pipe at the time of fuel injection by the injector can be suppressed.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a fuel rail according to the present invention will be described below with reference to the accompanying drawings. First Embodiment FIG. 1 is a sectional view showing a fuel rail according to a first embodiment of the present invention. In FIG. 1, reference numeral 1
0 indicates the entire fuel rail. The fuel rail 10 is used in a returnless type fuel supply device that supplies fuel to an automobile engine. Reference numeral 12 denotes a fuel supply pipe, and the fuel rail 10
Is connected to a fuel pump (not shown) via the fuel supply pipe 12.

The fuel rail 10 is formed of a box-shaped metal body case that is long in one direction.
The lower case 14 and the upper case 16 are divided into two parts, and the lower case 14 and the upper case 16 are connected by brazing. At the bottom of the lower case 14, a plurality of injector holders 18 on which injectors are mounted are attached at predetermined intervals in the longitudinal direction.

On the other hand, a housing-like wall panel 20 is mounted inside the upper case 16 so that
The air chamber 22 has a double structure partitioned in an airtight manner.
The wall panel 20 is made of a thin steel plate, and has an inner space 23 of the fuel rail 10 and an air chamber 22.
Are partitioned by partition walls 24. As the thin steel plate, preferably, a nickel-plated steel plate having a plate thickness of about 0.7 mm is used. The nickel-plated steel plate is drawn and formed into a thin box-like elongated box-shaped wall panel 20 with a flange. I have. The flange portion 20a is connected to the inner surface of the upper case 16 by brazing. An air hole 26 is opened at the center of the upper case 16, and the air hole 26 is sealed by inserting a cap member 28.

The fuel rail according to the present embodiment is constructed as described above. Next, the operation of the fuel rail will be described. In FIG. 1, when fuel discharged from a pump (not shown) is supplied to a fuel rail 10 through a fuel supply pipe 12, the fuel is distributed to the engine via an injector, and the fuel is supplied to the engine when the injector is opened. It is injected. At this time, although the pipe volume of the fuel supply system including the fuel rail 10 and the fuel supply pipe 12 tends to decrease by the amount of the injected fuel, the volume change is absorbed as follows.

That is, in the fuel 12, since air is sealed in the air chamber 22 defined by the wall panel 20, the volume in the pipe is reduced, and the pressure in the air chamber 22 and the fuel pressure in the internal space 23 are lost. If you try
The partition wall 24 made of a thin steel plate is deformed by the air pressure to absorb the decrease in the volume in the pipe. Thereby, a pressure change in the pipe at the time of fuel injection by the injector can be suppressed.

As described above, the upper case 16 is connected to the air chamber 22.
Has a double structure divided by a thin steel plate partition wall 24, so that the same function as a damper can be added to the fuel rail 10 while greatly reducing the number of parts.

Moreover, by using a nickel-plated steel plate as a material of the wall panel 20 constituting the partition wall 24, the inner wall surface of the air chamber 22 is preliminarily subjected to surface treatment by plating. Can be prevented, and the service life can be ensured for a long period of time.

Further, in the process of assembling the fuel rail 10, when the upper case 16, the wall panel 20, and the lower case 14 are integrated with each other by brazing in a furnace, the air holes 22 are opened. In addition, it is only necessary to seal the airtightness with the cap 28 after performing the airtightness inspection after being integrated, and it is possible to reliably check the airtightness, thereby improving the reliability. Also,
Even if the wall panel 20 is punctured during use,
There is an advantage that fuel does not leak outside.

Second Embodiment FIG. 2 is a sectional view showing a fuel rail according to a second embodiment of the present invention. The fuel rail 30 according to the second embodiment is different from the fuel rail 1 according to the first embodiment.
0 and the compartment structure of the air chamber 22 are different, and the other same components are denoted by the same reference numerals and detailed description thereof will be omitted.

In the second embodiment, a flat thin steel plate 34 is brazed by using an upper case 32 formed at a two-step bottom and the step 33 is used.
This is an embodiment in which the air chamber 22 is sectioned in an airtight manner by using as a partition. As described above, the upper case 32 has a large degree of freedom in design by combining the thin plate steel plate 34 with the double structure that partitions the air chamber 22, so that a flexible double structure can be provided according to the mounting space and the like.

[0021]

As is apparent from the above description, the fuel rail according to the present invention has a double-structured main body case in which an air chamber is air-tightly partitioned, and a partition for partitioning the air chamber is provided. Since it is made of a thin metal plate, it is excellent in suppressing the pressure change inside the fuel supply pipe at the time of fuel injection.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a fuel rail according to a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional view showing a fuel rail according to a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Fuel rail 12 Fuel supply pipe 14 Lower case 16 Upper case 18 Injector holder 20 Wall panel 22 Air chamber 23 Internal space 24 Partition wall 26 Air hole 28 Cap member 34 Thin steel plate

Claims (3)

[Claims] 1. A fuel rail connected to a fuel supply pipe for introducing fuel to an automobile engine and distributing fuel to an injector, comprising a main body case having a double structure in which an air chamber is partitioned in an airtight manner. A fuel rail, wherein a partition partitioning the chamber is made of a thin metal plate. 2. The main body case has an air chamber defined therein.
The fuel rail according to claim 1, comprising an upper case having a heavy structure, a lower case to which the injector holder is attached, and a cap member formed in the upper case and sealing an air hole communicating with the outside air through the air chamber. . 3. The fuel rail according to claim 1, wherein the thin metal plate is made of a Ni-plated steel plate.