JPS62225763A - Fuel pressure regulator - Google Patents

Abstract

PURPOSE:To make it possible to regulate the pressure of fuel with a high degree of accuracy with the use of a fuel regulator for an internal combustion engine, by welding first and second casing members forming a fuel chamber, together, and by disposing a metering valve in a discharge pipe which is associated with a shut-off valve. CONSTITUTION:First and second casing members 1, 2 forming a fuel chamber 3 are jointed together by ultrasonic welding along the entire circumference thereof. Thereby, even through there are some concave and convex recesses in their joint surfaces, the thus jointed parts may have sure fluid-tightness, and are never loosened. Further, a metering valve 7 associated with a shut-off valve 9 for a discharge pipe 5 is disposed in the latter. Thus, no fuel leakage or the like occurs in the fuel chamber so that it is possible to enhance the accuracy of pressure regulation, and the metering accuracy of discharged fuel is satisfactory, it is possible to regulate the pressure with a high degree of accuracy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fuel pressure regulator used in a fuel injection system for an internal combustion engine.

[Conventional technology]

Conventionally, for example, in the fuel piping system of a vehicle internal combustion engine equipped with an electronically controlled fuel injection device, in order to maintain a predetermined pressure difference between the pressure of the fuel injected from the fuel injection valve and the pressure in the intake pipe. A fuel pressure regulator is provided.

In this conventional fuel pressure regulator, the fuel amount and the back pressure chamber, which are configured by two divided cases, are partitioned by a pressure receiving body that is displaced by the pressure in the fuel chamber. The two cases are joined by tightening with the pressure receiving body sandwiched between them. This strangling force is set so that the pressure receiving body is appropriately displaced according to the pressure in the fuel chamber, and the fuel chamber and back pressure chamber are sealed (for example, Japanese Patent Publication No. 49-3704
No. 9).

[Problem that the invention seeks to solve]

However, when the fuel chamber is formed by such a tightening process, for example, if the case is made of resin or die-cast aluminum in order to reduce processing costs and product weight, the following problems arise: .

In other words, in the case of a resin case, if a dimensional change occurs due to deterioration of the constriction part, the constriction force of both cases will change, and the amount of displacement of the pressure receiving body that displaces in response to the fuel pressure controlled in the fuel chamber will change. There were times when it changed or the tightening part loosened.

In addition, when aluminum is formed by die-casting, slight cavities or irregularities on the sealing surface cause sealing failure after tightening, and the fuel chamber is not sufficiently sealed.

Sufficient pressure regulation has not been achieved in the fuel chamber constructed of the cases connected by the choke in this manner.

Therefore, the first object of the present invention is to improve the density in the fuel chamber, and the second object is to improve the metering accuracy of the fuel flowing out from the fuel chamber.

[Means for solving problems]

In order to solve the above problems, in the first invention, both the first case body and the second case body that constitute the fuel chamber in which the fuel inflow pipe and the fuel outflow pipe are opened are joined together by welding. In a second aspect of the invention, the fuel pressure regulator also has a metering valve in the outflow pipe nostril which is interlocked with the opening/closing valve of the outflow pipe.

[Effect]

According to the first invention, the two case bodies are joined by melting the joint surfaces, so the joint is not loosened or affected by slight irregularities before joining, and the tightness of the fuel chamber is ensured. Become something.

Furthermore, according to the second invention, it is possible to accurately measure the amount of outflowing fuel.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG.

The fuel pressure regulator 100 shown in FIG. 1 has a first case body 1 and a second case body 2, which are roughly cup-shaped in size and small. It is made of plastic resin, and has a first case body 1 and a second case body 2.
is contained therein, and a cup-shaped fuel chamber 3 is formed between the two. An annular protrusion 2 b formed on the flange edge 2 a of the second case body 2 is fitted into an annular groove 1 b formed on the flange edge 1 a of the first case body 1 .

Both edges 2a and 2b are welded together by ultrasonic bonding over the entire circumference.

An inlet pipe 4 is integrally formed on the side wall of the first case body 1, and communicates the fuel chamber 3 with a delivery pipe (not shown) that supplies fuel to a fuel injection valve (not shown), and into which fuel before metering flows. An outflow pipe 5 for returning surplus fuel after metering from the fuel chamber 3 to a fuel tank (not shown) is integrally formed on the bottom wall.

A stepped portion 5a is formed on the inner periphery of the outflow pipe 5, and locks one end of a spring 6 inserted into the outflow pipe 5. Also, it contacts the other end of the spring 6 and is biased in the direction of the fuel chamber 3,
A substantially cylindrical metering valve 7 for metering the amount of fuel flowing out from the fuel chamber 3 is provided so as to be slidable in the axial direction within the outflow pipe 5.

Four chamfered portions 7a are formed on the side surface of this metering valve 7, and form an outflow passage for excess fuel between the metering valve 7 and the outflow pipe 5. The remaining side surface which is not chamfered is a cylindrical surface serving as a sliding surface 7b for sliding the metering valve 7 relative to the outflow pipe 5. Further, a spherical surface is formed on the head 7C at the tip of the valve.

A bellows 8 as a pressure-receiving body that fluctuates depending on the pressure within the fuel chamber 3 is integrally formed in a portion of the second case body 2 that is accommodated in the first case body 1 . The bottom surface of the bellows 8 is a pressure receiving surface 8a that receives the pressure of the fuel chamber 3, and the head portion 7C of the metering valve 7 is in contact with it due to the biasing force of the spring 6.

The valve 7 and the bellows 8 can move in the axial direction. An annular on-off valve 9 made of rubber is welded to the peripheral end of the pressure receiving surface 8a in order to seal the fuel flowing into the opening 5b. The bellows 8 has a structure in which its side wall portion can be expanded and contracted so that the on-off valve 9 can move in the axial direction within the first case body 1.

Inside the second case body 2 is a back pressure chamber 10 as a pressure chamber.
is formed, and is separated from the fuel chamber 3 by a bellows 8. A spring 11 is inserted into the back pressure chamber 10 and is fixed by being screwed into the open end of the case body 2, and is sandwiched between a back pressure pipe 12 connected downstream of the throttle valve of an intake pipe (not shown) and the bellows 8. . The spring 11 urges the bellows 8 in the direction of extending the bellows 8, that is, in the direction of closing the on-off valve 9. The biasing force of the spring 11 can be adjusted by adjusting the screwing amount of the back pressure pipe 12. On the other hand, the biasing force of the spring 6 is smaller than the biasing force of the spring 11, and is such that the 11-volume valve 7 follows the displacement of the bellows 8.

In the above configuration, the inside of the fuel chamber 3 is filled with fuel that is pumped from a fuel tank (not shown) to the inflow pipe 4 by a fuel pump, and the intake pressure downstream of the throttle valve in the intake pipe is introduced into the back pressure chamber 10.

The pressure inside the fuel chamber 3 is lower than the pressure inside the back pressure chamber 10 by a predetermined amount (biasing force of the spring 11/pressure receiving surface 8a of the bellows 8).
The fuel pressure on the pressure receiving surface 8a exceeds the predetermined pressure determined by the biasing force of the spring 11 and the pressure in the back pressure chamber 10. The bellows 8 contracts, and the opening/closing valve 9, which cooperates with the displacement of the bellows 8, separates from the first case body 1 and opens the opening 5a of the outflow pipe 5. Then, the metering valve 7 that follows the bellows 8 measures the amount of fuel flowing out through its chamfered portion 7a in accordance with the lift amount, and this flowing out fuel is returned to the fuel tank through the outflow pipe 5a. When the pressure within the fuel chamber 3 increases in this way, a portion of the fuel is allowed to flow out of the fuel chamber 3, thereby controlling the pressure within the fuel chamber 3 to a predetermined pressure state. That is, the fuel pressure sent to the injection valve;
The pressure difference between the intake pressure and the intake pressure is always constant, making it possible to achieve continuous fuel injection.

Furthermore, when the internal combustion engine stops, the fuel pump stops pumping fuel, so the spring 11 immediately urges the bellows 8, seats the rubber on-off valve 9 on the first case body 1, and completely closes the opening 5b. By sealing, the residual pressure inside the fuel chamber 3 and the delivery vibe is maintained. This facilitates restarting the internal combustion engine.

An on-off valve 9 and a metering valve 7 are provided at the opening 5a of the outflow pipe 5.
Since the two valves are provided, the amount of outflowing fuel is once reduced to a certain extent by the on-off valve 9 and then metered by the metering valve 7, resulting in good metering accuracy. Furthermore, even if the rubber of the on-off valve 9 deteriorates and its shape changes and the distance between the on-off valve 9 and the first case l changes, the metering valve 7 is provided so that the outflowing fuel can be accurately measured over a long period of time. is measured. Also,
Due to the spherical surface forming the head 7c of the metering valve 7, the bellows 8
and the metering valve 7 can follow each other while reliably contacting each other even if there is some shape error or assembly error.

In addition, by employing the substantially cup-shaped bellows 8 as the pressure receiving body, the back pressure chamber 10 is formed inside the fuel chamber 3, so that the fuel pressure regulator 100 is miniaturized.

Further, since the second case body 2 and the bellows 8 are integrally formed of the same member, the fuel chamber 3 and the back pressure chamber 10 are completely separated and are completely airtight.

In the above embodiment, the first case body and the second case body were made of resin, but the first case body may be made of aluminum molded by die-casting, and the second case body may be made of a metal material such as stainless steel. , it is also possible to have a structure in which both are welded together by resistance welding or the like. With this configuration, even if there are some cavities on the bonding surfaces, it does not matter because they will melt after surface force during bonding. Further, the back pressure pipe may be fixed to the second case body by welding. Further, the bellows may also be made of metal and may be fixed to the second case body by welding.

Further, although a spring is disposed in the back pressure chamber, it is also possible to eliminate this spring, provide the bellows with operational rigidity, and set the biasing force of the opening/closing valve using only the bellows.

Alternatively, a delivery pipe provided with a fuel injection valve for injecting fuel into the internal combustion engine may serve as an inflow pipe and a fuel chamber, and an outflow pipe may be connected to this delivery pipe.

〔Effect of the invention〕

As described above, according to the first invention, the first case body and the second case body constituting the fuel chamber are joined by welding, so that some irregularities on the joint surface are melted away. The joint has reliable tightness and will not come loose. Therefore, no fuel leakage occurs in the fuel chamber, so the accuracy of pressure adjustment in the fuel chamber is very high. Furthermore, in the second aspect of the invention, since the metering valve is provided in the outflow pipe, the metering accuracy of the outflowing fuel is also improved. Therefore, an excellent fuel pressure regulator capable of highly accurate pressure regulation can be provided.

[Brief explanation of drawings]

The accompanying drawing is a longitudinal sectional view of a fuel pressure regulator according to an embodiment of the present invention. 1... First case body, 2... Second case body, 3
...Fuel chamber, 4...Inflow pipe, 5...Outflow pipe, 5b
... opening, 7... metering valve, 8... bellows as a pressure receiving body. 9... Opening/closing valve, 10... Back pressure chamber as a pressure chamber, 1
00...Fuel pressure regulator. Representative Patent Attorney Takashi Okabe 2, Nu 2's Goo Case 5b, Ii D
Room 341 7: Adjustment valve 4', ;L)'' pipe
8: To eFL4LLtn °o-7. -5,
Evasion pipe 9: Between rA and 1o: Pressure nt1-Lτtn4Hi 100; GiN! ilB

Claims (5)

[Claims] (1) A first case body and a second case body that are connected to each other to form a chamber inside, a pressure receiving body that separates this chamber into a fuel chamber and a pressure chamber, and a pressure receiving body that opens into this fuel chamber. It includes a fuel inflow pipe, a fuel outflow pipe, and an on-off valve that cooperates with the pressure receiving body to open and close an opening of the outflow pipe to adjust the pressure of the fuel according to the pressure in the pressure chamber. The fuel pressure regulator is characterized in that the first case body and the second case body are joined by welding. (2) The inflow pipe and the outflow pipe are provided in the first case body, and the pressure receiving body is provided in the second case body. Fuel pressure regulator. (3) The fuel pressure regulator according to claim 2, wherein the pressure receiving body is a bellows and is integrally formed with the second case body. (4) The fuel pressure regulator according to claim 3, wherein the second case body on which the bellows is formed is made of resin. (5) A first case body and a second case body that are connected to each other to form a chamber inside, a pressure receiving body that separates this chamber into a fuel chamber and a pressure chamber, and a pressure receiving body that opens into this fuel chamber. It includes a fuel inflow pipe, a fuel outflow pipe, and an on-off valve that cooperates with the pressure receiving body to open and close an opening of the outflow pipe to adjust the pressure of the fuel according to the pressure in the pressure chamber. The first case body and the second case body are coupled by welding, and a metering valve is further provided in the outflow pipe to adjust the amount of outflowing fuel in conjunction with the on-off valve. A fuel pressure regulator featuring: