JPH0220456Y2 - - Google Patents

Description

[Detailed description of the invention] [Purpose of the invention] (Field of industrial application) The present invention relates to a fuel pressure pulsation prevention device, for example, a fuel pressure pulsation prevention device used in an internal combustion engine, particularly an electronic fuel injection system. Used as a device.

(Prior art) In electronic fuel injection systems, fuel pressure in the fuel system pulsates due to fuel injection and fuel pump operation, which adversely affects the air-fuel ratio of the engine and causes noise. Ta.

As a method for preventing this fuel pressure pulsation, for example, there is a method disclosed in Japanese Utility Model Application Laid-Open No. 55-20620. In this invention, an elastic membrane body or an elastic membrane bag forms a pneumatic chamber that airtightly separates the pulsations occurring within the main fuel supply pipe from the fuel, and contracts and expands the air within this pneumatic chamber.
Prevents fuel pressure pulsation.

(Problem to be solved by the invention) However, with the above-mentioned elastic membrane, the outer circumference of the membrane is fitted into a part of the main fuel supply pipe, which increases the outer diameter of the main fuel supply pipe. This is extremely disadvantageous when mounted on a vehicle.

Therefore, the first technical problem of this invention is to be able to install a device that prevents fuel pressure pulsation on the delivery pipe without increasing the outer diameter of the main fuel supply pipe (delivery pipe). do.

Furthermore, since the pneumatic chamber has a closed structure, it is difficult to obtain a change in volume due to a change in the pressure in the pneumatic chamber, resulting in a poor damper effect.

Therefore, the second technical problem of the present invention is to construct a device that prevents pulsation of fuel pressure without making the pneumatic chamber a sealed structure.

Furthermore, if the air pressure chamber does not have a sealed structure, there is a risk that fuel may leak to the outside when the partitioning member that partitions the fuel chamber and the air pressure chamber is damaged.

Therefore, the third technical problem of the present invention is to prevent fuel from leaking to the outside even when the partition member is damaged.

[Structure of the idea]

(Means for Solving the Problems) The technical means of the present invention taken in order to solve the first to third technical problems of the present invention described above is that a pneumatic chamber and a fuel delivery pipe opened to the atmosphere are connected to the air pressure chamber and the fuel delivery pipe. a body having a communicating fuel chamber; a movable body that is slidably housed in the body in the axial direction and is exposed to the fuel chamber on one side and exposed to the air pressure chamber on the other side; A first spring biased to a position regulated by a resistor stopper, a cup seal disposed in an outer circumferential groove of the movable body and airtightly partitioning a fuel chamber and an air pressure chamber, and a cup seal formed on the cup seal and disposed in the outer circumferential groove of the movable body. A pulsating damper constituted by a lip that contacts the inner peripheral surface, a valve housed in a pneumatic chamber in series with the movable body, and a second valve that biases the valve in a direction away from the seat once formed in the body. The fuel delivery pipe is equipped with a spring, and the body is inserted from the open end of the fuel delivery pipe.

(Function) According to the above-mentioned technical means of the present invention, the body with the pulsation damper incorporated therein is inserted from the open end of the fuel delivery pipe, thereby eliminating the need to increase the outer circumferential diameter of the fuel delivery pipe. ,
No problems will occur when installed in a vehicle.

In addition, since the air pressure chamber is open to the atmosphere, the damper effect is excellent, and at the same time, a safety mechanism consisting of valves etc. is incorporated, so
Even if the cup seal is damaged and the fuel inside the fuel delivery pipe leaks into the air pressure chamber, it will not leak outside.

(Example) Hereinafter, an example embodying the technical means of the present invention will be described based on the accompanying drawings.

Fuel delivery pipe (hereinafter abbreviated as pipe)
10 is connected to joint 1 through seals 11 and 12.
3. It has a member 15 that is screwed onto the pipe 10 to position and hold the pipe 14. The pipe 14 is connected to a fuel tank via a fuel pump (not shown), and fuel is supplied to the fuel chamber 17 of the pipe 10 via a passage 16 formed in the member 15. This fuel chamber 17 leads to a fuel injector (not shown) on one side, and is connected to the aforementioned fuel tank via a regulator valve on the other side.

The pipe 10 is closed on one side with a cover 18,
A pulsation damper 19 is fitted into the other end. The pulsation damper 19 includes a cylindrical body 22 that is positioned and arranged with respect to the shoulder 20 of the pipe 10 via an O-ring 31, and then held by caulking the open end 21 of the pipe 10; It has a piston-like movable body 25 which is movably disposed within the body 22 and is normally biased to the illustrated position regulated by a stopper 24 fitted into the body 22 by a spring 23. This movable body 25
has an outer circumferential groove 26 in which the body 2 is inserted.
A cup seal 28 is fitted having a lip 27 in contact with the inner periphery of the fuel chamber 17.
is airtightly separated from the pneumatic chamber 29. The outer periphery of the movable body 25 has an extending portion 30, which functions as a sliding guide portion within the body 22 and also has a function of preventing the cup seal 28 from tilting. The movable body 25 slides in the axial direction due to the pulsation of fuel pressure in the fuel chamber 17 against the spring 23, thereby absorbing the pulsation.

A valve 35 is disposed within a retainer 32 that receives the end of the spring 23 and is spaced apart from a seat 34 normally formed in the body 22 by a relatively weak spring 33. Therefore, under normal conditions, the pneumatic chamber 29 is located in the passage 3 formed in the retainer 32.
6. Although it communicates with the outside through a passage 37 formed in the body 22, if the fuel in the fuel chamber 17 leaks into the air pressure chamber 29 due to breakage of the cup seal 28, etc., the fuel pressure The valve 35 contacts the seat 34 to prevent fuel from leaking to the outside, and the valve 35 ultimately functions as a safety device.

The pulsation damper 19 described above is configured in a so-called capsule shape, and after arranging each part constituting the pulsation damper 19 in the body 22, it is only necessary to fit it into the open end of the pipe 10. There is no need for positioning via a screw or for forming a mounting boss or flange. Note that the safety device including the valve 35 does not necessarily need to be incorporated into the pulsation damper 19, and may be provided in series with the pulsation damper 19.

[Effect of idea]

As shown above, in this invention, the body with the pulsation damper built into it is inserted from the open end of the fuel delivery pipe, so there is no need to increase the outer diameter of the fuel delivery pipe, and it can be used even when mounted on a vehicle. No problems will occur.

In addition, since the pneumatic chamber is open to the atmosphere, even if the movable body moves, the pressure inside the pneumatic chamber will not increase, and the movement of the movable body will not be hindered, so the maximum movement of the movable body will increase, resulting in a damper effect. will be excellent.

Furthermore, a safety mechanism consisting of valves, etc. is integrated, so even if the movable body or cup seal is damaged and fuel in the fuel delivery pipe leaks into the air pressure chamber, it will not leak outside and the vehicle will be protected. There is no risk of causing a fire.

[Brief explanation of drawings]

The drawing shows a sectional view of a fuel pressure pulsation prevention device showing an embodiment of the present invention. 10... Fuel delivery pipe, 17... Fuel chamber, 19... Pulsation damper, 22... Body, 23
...First spring, 24...Stopper, 25...
...Movable body, 27...Lip, 28...Cup seal, 29...Pneumatic chamber, 33...Second spring, 34...Seat, 35...Valve.

Claims (1)

[Scope of Claim for Utility Model Registration] A body having a pneumatic chamber open to the atmosphere and a fuel chamber communicating with a fuel delivery pipe; a movable body exposed to the air pressure chamber on the other side; a first spring that biases the movable body against fuel pressure to a position regulated by a stopper; and a first spring disposed within an outer circumferential groove of the movable body. a pulsation damper including a cup seal that airtightly partitions the fuel chamber and the pneumatic chamber; and a lip formed on the cup seal and in contact with the inner circumferential surface of the body; and a second spring that urges the valve away from the once-formed seat of the body, the body being inserted from the open end of the fuel delivery pipe. Fuel pressure pulsation prevention device.