GB2354815A

GB2354815A - Pressure regulating valve

Info

Publication number: GB2354815A
Application number: GB0019592A
Authority: GB
Inventors: Legrand Philippe
Original assignee: Delphi Technologies Inc
Current assignee: Delphi Technologies Inc
Priority date: 1999-08-18
Filing date: 2000-08-10
Publication date: 2001-04-04
Also published as: GB9919423D0; GB0019592D0

Abstract

A valve comprises a spring 26 having a surface 26a engageable with a seating 32 to regulate fluid pressure in a chamber 12. The spring 26 is preferably a helical spring having a leg 26b at the end of which is surface 26a. Preferably the opposite end of the spring cooperates with a setting member. The spring is preferably housed within a spring chamber 24 which is defined by a first valve housing 14, which may be housed within a second valve housing 18.

Description

1 2354815 VALVE The invention relates to a valve for regulating fluid

pressure. In particular, but not exclusively, the invention relates to a valve for regulating the pressure of fuel within part of a fuel system.

In fuel systems, fuel pressure can be regulated by means of a pressure limiting valve. Known pressure limiting valves typically include a piston member which is slidable within a bore and is engageable with a seating to control fluid communication between a first chamber, at relatively high fuel pressure, and a second chamber at a lower pressure. The piston member is biased towards a valve seating by means of a compression spring such that, with the piston member seated against the seating, communication between the first and second chambers is broken. Fuel pressure within the first chamber acts on a surface associated with the piston member and opposes the biasing force of the spring such that, when fuel pressure within the first chamber exceeds a predetermined amount, the piston member is urged away from the seating to permit fuel flow from the first chamber to the second chamber. In this way, fuel pressure within the first chamber can be regulated such that it does not exceed a predetermined amount. However, valves of this type have several components and the cost of manufacture can be undesirably high for some applications.

It is an object of the present invention to provide an alternative type of valve which is of simpler form and is relatively inexpensive to manufacture.

According to the present invention, there is provide a valve for regulating fluid pressure within a chamber, the valve comprising a spring which acts against fluid pressure within the chamber, the spring having a surface which is engageable with a valve seating to regulate fluid pressure within the chamber.

Conveniently, in use, when fluid pressure within the chamber exceeds a predetermined amount, the force applied to the surface by fluid pressure within the chamber overcomes the biasing force of the spring and the surface of the spring is lifted away from the valve seating. Thus, fluid pressure within the chamber is regulated so as not to exceed the predetermined amount. Typically, the chamber may be a flow passage for fuel which forms part of a fuel system, the valve thereby regulating fuel pressure within the flow passage.

As the surface of the spring itself is engageable with the valve seating, the construction of the valve is simplified compared to known pressure limiting valves and the cost of manufacture can therefore be reduced. Typically, the spring may be a helical compression spring.

Conveniently, the spring may be housed within a spring chamber which is defined, at least in part, by a recess or bore provided in a first valve housing. The first valve housing may be retained within a recess or bore provided in a second valve housing.

The valve may also include a setting member which cooperates with the spring so as to bias the spring towards the valve seating, the biasing force applied to the spring being determined by the position of the setting member within the bore. Thus, the predetermined fuel pressure at which the surface of the spring lifts away from the valve seating can be selected by selecting the position of the setting member within the bore.

The valve seating may be defined by a seating member, at least a part of which may be received within the first valve housing. Alternatively, the valve seating may be defined by the second valve housing.

The invention will now be described, by way of example only, with reference to the accompanying drawings in which:- Figure 1 is a schematic view of a valve in accordance with a first embodiment of the present invention; and Figure 2 is a schematic view of an alternative embodiment.

Referring to Figure 1, there is shown a valve, referred to generally as 10, for controlling fuel pressure within an inlet chamber or passage 12 forming part of a fuel system. The valve 10 includes a first valve housing 14 which is arranged within a recess 16 provided in a second valve housing 18. The valve housing 14 may be fixed in position within the recess 16 by any suitable technique, for example by screw threaded engagement or by welding. A seal member 20 is also provided to seal the first valve housing 14 to the second valve housing 18. The valve housing 14 is provided with a through bore 22 which defines a spring chamber 24 within which a compression spring 26 is housed. The inlet passage 12 includes a region 12a of reduced diameter which communicates with the spring chamber 24, the spring chamber 24 also communicating with an outlet passage 25, defined in the first and second valve housings 14, 18, which is connected to a low pressure fuel reservoir.

The inlet passage 12 is defined, in part, within a seating member 30 which is retained within the recess 16 by any suitable means, for example by clamping the seating member 30 in position by the housing 14. The mounting of the seating member 30 within the recess 16 is such as to form a seal between the seating member 30 and the housing 18. The seating member 30 includes a rep-ion 30a of reduced diameter which is received within the lower, open end of the through bore 22. The region 30a of the seating member 30 defines a seating surface 32 of substantially frusto- conical form, with which a surface 26a, defined by an end of the compression spring 26, is engageable to control fuel flow from the inlet passage 12 to the spring chamber 24. As illustrated, the spring 26 is conveniently shaped to define a leg 26b, which extends substantially along the axis of the spring 26, the end of the leg 26b defining the surface 26a.

At the end of the compression spring 26 remote from the surface 26a, the spring 26 engages a setting member 34 which is received in the upper open end of the through bore 22. The setting member 34 is secured in position within the bore 22 by any suitable means. The setting member 34 loads the spring 26 and serves to bias the surface 26a of the spring 26 towards the seating surface 32, the load on the spring being determined by the position of the setting member 34 within the bore 22.

In use, fuel is supplied to the inlet passage 12 from a downstream part of the fuel system (not shown). 'Fuel pressure within the inlet passage 12 acts on the surface 26a of the compression spring 26, fuel pressure within the inlet passage 12 acting to oppose the biasing force of the compression spring 26. When the force applied to the surface 26a due to fuel pressure within the inlet passage 12 exceeds the biasing force of the spring 26, the surface 26a of the spring is urged away from the seating surface 32. With the surface 26a lifted away from the seating surface 32, fuel within the inlet passage 12 is able to flow past the seating surface 32, into the spring chamber. 24 and out through the outlet passage 25 to the low pressure fuel reservoir. Fuel pressure within the inlet passage 12 is therefore reduced. The fuel pressure at which the valve opens depends upon the spring force of the spring 26 and the effective area of the surface of the i spring 26 exposed to fuel pressure in the passage 12.

If the force on the surfac C! 26a due to fuel pressure within the inlet passage 12 is reduced to an amount less than the biasing force of the compression spring 26, the surface 26a of the spring 26 is retumed to its seated position under the action of the biasing force of the spring 26. Thus, fuel in the inlet passage 12 is no longer able to flow past the seating surface 32 into the spring chamber 24 and out through the outlet passage 25 to low pressure.

If fuel pressure within the inlet passage 12 is subsequently increased such that the force applied to the surface 26a exceeds the biasing force of the spring 26, the spring 26 will once against be urged away from the seating surface 32, as described previously. Thus, the valve 10 permits fuel pressure within the inlet passage 12 to be regulated such that it does not exceed a predetermined value which is determined by the load applied to the spring 26 by the setting member 34. It will be appreciated that the position of the setting member 34 within the bore 22 determines the load which is applied to the compression spring 26. Thus, the position of the setting member 34 within the bore 22 determines the maximum fuel pressure within the inlet passage 12.

An alternative embodiment is shown in Figure 2, in which the valve housing 14 is removed, a bore 36 being provided in the second valve housing 18 to defte the spring chamber 24. In this embodiment of the invention, the seating member 30 is also removed, the valve housing 18 defining the seating surface 32a with which the surface 26a of the compression spring 26 is engageable to control fuel pressure within the inlet passage 12.

In the present invention, as the compression spring 26 itself is engageable with the seating surface 32 to control fuel pressure within the inlet passage 12, the valve 10 is of simpler form and is easier to manufacture than conventional pressure relief valves.

Preferably, the surface 26a of the compression spring 26 is coated with a hard coating to increase the service life of the valve 10. The surface 26a of the compression spring 26 may be of frusto-conical form or may, for example, have a spherical shape, the seating surface 32 being shaped to cooperate with the surface 26a of the compression spring 26.

It will be appreciated that the setting member 34 in Figures 1 and 2 and the seating member 30 in Figure I may be retained in their respective positions by means other than those shown. It will also be appreciated that alternative types of spring to that shown in the accompanying drawings may also be used.

I CLABIS 1. A valve for regulating fluid pressure within a chamber, the valve comprising a spring which acts against fluid pressure within the chamber, the spring having a surface which is engageable with a valve seating to regulate fluid pressure within tile chamber.

Claims

2. The valve as claimed in Claim 1, wherein the spring is arranged such

that, in use, When fluid pressure within the chamber exceeds a predetermined amount, the force applied to the surface by fluid pressure within the chamber overcomes the biasing force of the spring, thereby causing the surface of the spring to lift away from the valve seating.

3. The valve as claimed in Claim 1 or Claim 2, wherein the chamber is a flow passage for fuel which forms part of a fuel system, the valve serving to regulate fuel pressure within the flow passage.

4. The valve as claimed in any of Claims 1 to 3, wherein the spring is a helical compression spring.

5. The valve as claimed in any of Claims 1 to 4, wherein the spring is housed within a spring chamber which is defined, at least in part, by a recess or bore provided in a first valve housing.

6. The valve as claimed in Claim 5, wherein the first valve housing is retained within a recess or bore provided in a second valve housing.

7. The valve as claimed in any of Claims I to 6, wherein the valve includes a setting member which cooperates with the spring so as to bias the spring towards the valve seating, the biasing force applied to the spring being determined by the position of the setting member within the bore.

8. The valve as claimed in any of Claims 5 to 7, wherein the valve seating is defmed by a seating member, at least a part of which may be received within the first valve housing.

9. The valve as claimed in any of Claims 6 to 8, wherein the valve seating is defined by the second valve housing.

10. A valve substantially as herein described with reference to the accompanying figures.