GB2202308A - Pressure control valves - Google Patents

Abstract

A pressure control valve comprises a body having an inlet chamber 8, an outlet chamber 20 and a passage between the two chambers, a valve seat 14 located in the passage, a valve member 15 located within the body and movable between a closed position in which it engages the valve seat to prevent fluid flow through said passage and an open position in which said flow is permitted, and biasing means 27 urging the valve member 15 towards said open position, the valve member 15 being responsive to fluid pressure in said outlet chamber 20 so as to move to said closed position when that fluid pressure is above a predetermined value, the outlet chamber 20 being capable of receiving a non-return device 30 therein for shutting off return flow through the passage. <IMAGE>

Description

PRESSURE CONTROL VALVES This invention relates to valves for controlling pressure in a fluid flow system and the control may be for the purpose of either reducing or limiting the pressure in that system. It will be convenient to hereinafter describe the invention with particular reference to pressure limiting valves, but that is not the only application of the invention.

Pressure control valves are generally of relatively bulky and complex construction. Furthermore, such valves sometimes require the inclusion of a one-way flow or non-return facility, and that generally requires use of a valve body different from that used for a valve not having such a facility. Manufacturing costs are thereby increased.

It is an object of the present invention to provide a pressure control valve which is of relatively simple construction and which can incorporate a facility of the aforementioned kind without major change to the form of its body dr any other major component of the valve.

According to the invention there is provided a pressure control valve comprising body having an inlet chamber, an outlet chamber and a passage between the two chambers, a valve seat located in the passage, a valve member -located within the body and movable between a closed position in which it engages the valve seat to prevent fluid flow through said passage and an open position in which said flow is permitted, and biasing means urging the valve member towards said open position, the valve member being responsive to fluid pressure in said outlet chamber so as to move to said closed position when that fluid pressure is above a predetermined value, the outlet chamber being capable of receiving a nonreturn device therein for shutting off return flow through the passage.

Preferably, the passage comprises a cylindrical bore and the valve member comprises a piston, slidable in said cylindrical bore between said open and closed positions, with at least one face of the piston facing towards the outlet chamber so as to be reacted on by fluid pressure in the outlet chamber.

The piston may be of stepped configuration defining a head and a stem, the head being of greater diameter than the stem and the piston having a passage therethrough, the body having an internal transverse wall extending into the cylindrical bore between its ends, the transverse wall having a bore therethrough through which the stem of the piston extends in a relatively movable sealed relationship, the head of the piston being in relatively movable sealed relationship with the cylindrical bore, and an annular chamber being defined around the stem between the transverse wall and the head of the piston.

Preferably' the body comprises a primary part and an outlet part, said outlet chamber being formed at least in part by said outlet part, and connecting means connecting said primary and outlet.parts so that said parts can be separated to permit a non-return facility to be located within or removed from said body according to requirements, said non-return facility when included being operative to prevent fluid flow from said outlet chamber towards said inlet chamber.

Two embodiments of the invention are described in detail, by way of example only, in the following passages of the specification which refer to the accompanying drawings, in which: Figure 1 shows a cross sectional side view of a control valve according to the invention, without a non-return device located therein; and Figure 2 shows a similar view of a valve similar to that of Figure 1, but in which the valve is fitted with a non-return device.

A valve 1 is shown in Figure 1 of the drawings and has inlet port 2 and outlet port 3 arranged in co-axial relationship. The valve is formed of three parts which may be conveniently referred to as inlet, primary and outlet parts 4, 5 and 6 respectively. That terminology, however, is not to be understood as imposing a strict relationship between each part as hereinafter described, or imposing a particular direction of flow through the valve 1 under all conditions of use.

The primary part 5 is of open-ended tubular form having an internal transverse wall 7 between its ends. An inlet chamber 8 is defined between that internal wall and an end of the primary part, and an axial opening 9 is provided through the internal wall 7 for a reason hereinafter made clear.

Each of the inlet and outlet parts is also preferably a tubular member which is arranged to be secured to a respective end of the primary part 5 in co-axial relationship. The outlet part 6 may be open-ended to define an outlet passage therethrough, whereas the inlet prt 4 is not, at least in the particular embodiment being described. Each of the inlet and outlet parts may be secured to the primary part 5 through co-operable screw threads 10.

In the arrangement shown, the inlet part 4 has an internal passage extending from its outer end 11 to an end wall 12 at its inner end. That inner end is contained within the inlet chamber 8 of the primary part 5, and a plurality of transfer ports 13 extend through the side wall of the inlet part 4 to provide communication between the internal passage of that part and the inlet chamber 8. A resilient disc or annulus 14 is provided at the inner end of the inlet part to form a valve seat which functions as hereinafter described.

A valve member 15 is mounted within the primary part 5 so as to be disposed between the inlet and outlet parts and so as to be movable towards and away from the valve seat 14. The valve member 15 preferably has a stepped configuration including a stem section 16 which is slidably located in the aforementioned opening 9 through the internal wall 7, and an enlarged head section 17 which is slidably mounted in a bore portion 18 extending between the internal wall 7 and the outlet part 6. The head section 17 is at one end of the stem section 16 and divides the aforementioned bore portion 18 into a spring chamber 19 and an outlet chamber 20. Any suitable sealing means may be provided between each of those valve member sections and the surfaces over which they move, and in the preferred embodiment shown O-ring seals 22 serve as the sealing means.

An axial bore 23 extends completely through the valve member 15, and that bore 23 is enlarged (as shown at numeral 24) at the head section end for a reason hereinafter made clear. The end 25 of the stem section 16 remote from the head section 17may be chamfered or otherwise formed to provide a relatively narrow annular zone for engagement with the aforementioned valve seat 14. Such engagement limits movement of the valve member in one direction, and movement in the opposite direction may be limited. by engagement of the valve member with an inwardly facing end surface 26 of the outlet part.

A coil compression spring 27 is contained within the spring chamber 19 and acts between the head section 17 and the internal wall 7 to urge the valve member 15 away from the valve seat 14. An air bleed hole 28 may be provided through an external wall of the spring chamber 19 to facilitate movement of the valve member 15.

Under normal conditions of operation, fluid pressure within the outlet chamber 20 acts against the head section 17 so as to apply a closing force to the valve member 15. If that pressure is high enough, the valve member 15 will move to engage the valve seat 14 and thereby close the valve. When the outlet chamber pressure falls below a particular level, however, the spring 27 force predominates and therefore causes the' valve member 15 to move away from the valve seat 14 to open the valve. As a consequence of such movement, fluid within the inlet chamber 8 is able to enter and pass through the axial passage 23 of the valve member 15 and thereby enter the outlet chamber 20.

The arrangement is such that the fluid pressure within the valve body imposes a net closing force on the valve member 15. That arises because the surface area of the valve member 15 which is exposed to pressure within the outlet chamber 20 is larger than the surface area exposed to pressure within the inlet chamber 8. In that regard, the relevant surface area is that of surfaces arranged transverse to or angularly relative to the longitudinal axis of the valve member. The closing force imposed by fluid pressure is countered by the spring force so that closing will not occur below a particular pressure, which can be predetermined. The strength of the spring 27 may be altered to alter the closing force required to close the valve 1.

As shown in Figure 2, a one-way or non-return facility can be easily incorporated in a valve as described with reference to Figure 1. In Figure 2 of the drawings, parts similar to the parts described with reference to Figure 1 are given like numerals. Outlet part 6a in Figure 2 has said non-return facility incorporated therein. The non-return facility shown includes a closure member 30 which is located within the outlet chamber 20 and is arranged to close the adjacent end of the axial passage 23 through the valve member 15.

The closure member 30 includes a spindle 31 which is slidably mounted in a support member 32 which is mounted within outlet part 6a. A head portion 34 at one end of the spindle 31 is engageable with a seat formed around the enlarged opening 24 of the aforementioned axial passage 23. A resilient sealing disc 35 is located on the head portion 34 so as to be engageable with the valve seat around the enlarged opening 24.

The support member 32 is located within the adjacent end portion of the outlet passage through the outlet part 6a and can be secured against relative movement in any appropriate fashion. The support member 32 has a central boss 36 which slidably receives the spindle 31 and a plurality of openings 37 located radially outwardly of the boss 36 through which the outlet port 3 and the outlet chamber 20 communicate. A spring 38 acts between the support member 32 and the head portion 34 to urge the closure member 30 into a flow blocking position.

The outlet part 6a shown in Figure 2 is somewhat different to the outlet part 6 shown in Figure 1 of the drawings in that said part 6a includes the nonreturn facility. The outlet part 6a may be used in the valve of Figure 1 and, likewise, the outlet part 6 shown in Figure 1 may be used in the valve of Figure 2.

In the embodiment shown in Figure 2 a stop element is provided within the outlet chamber 20 between the outlet part 6a and the valve member 15 so as to limit travel of the valve member 15 away from its valve seat 14. That element in this embodiment comprises a circlip 39 or the like snap engaged within a circumferential groove provided in the wall of the outlet chamber 20.

A valve 1 as described is open to substantial variation. By way of example, the valve seat of the inlet part 4 and the co-operating portion of the valve member 15 may be formed by or include substantially complementary tapered surfaces. A resilient O-ring or other annular member may be attached to one of those surfaces so as to be engageable by the other in the manner described in relation to Figures 4 to 6 of Australian patent application no: 62393/86.

It will be apparent from the foregoing description that a valve according to the invention is of very simple construction and can be manufactured at a relatively low cost. It will be further apparent that the valve is able to accept a one-way or non-return facility without requiring alteration to its major components.

Claims (10)

1. A pressure control valve comprising a body having an inlet chamber, an outlet chamber and a passage between the two chambers, a valve seat located in the passage, a valve member located within the body and movable between a closed position in which it engages the valve seat to prevent fluid flow through said passage and an open position in which said flow is permitted, and biasing means urging the valve member towards said open position, the valve member being responsive to fluid pressure in said outlet chamber so as to move to said closed position when that fluid pressure is above a predetermined value, the outlet chamber being capable of receiving a non-return device therein for shutting off return flow through the passage.

2. A pressure control valve according to claim 1 wherein the passage comprises a cylindrical bore and the valve member comprises a piston, slidable in said cylindrical bore between said open and closed positions, with at least one face of the piston facing towards the outlet chamber so as to be reacted on by fluid pressure in the outlet chamber.

3. A pressure control valve according to claim 2 wherein the piston is of stepped configuration defining a head and a stem, the head being of greater diameter than the stem and the piston having a passage therethrough, the body having an internal transverse wall extending into the cylindrical bore between its ends, the transverse wall having a bore therethrough through which the stem of the piston extends in a relatively movable sealed relationship, the head of the piston being in relatively movable sealed relationship with the cylindrical bore, and an annular chamber being defined around the stem between the transverse wall and the head of the piston.

4. A pressure control valve according to any preceding claim wherein said body comprises a primary part and an outlet part, said outlet chamber being formed at least in part by said outlet part, and connecting means connecting said primary and outlet parts so that said parts can be separated to permit a non-return facility to be located within or removed from said body according to requirements, said non-return facility when included being operative to prevent fluid flow from said outlet chamber towards said inlet chamber.

5. A pressure control valve according to claim 4 wherein said inlet chamber is formed, at least in part, by said primary part.

6. A pressure control valve according to claim 5 wherein an inlet part is connected to said primary part and forms part of said inlet chamber, said valve seat being formed on said inlet part.

7. A pressure control valve according to any one of claims 4 to 6 wherein the non-return facility comprises a non-return valve closure member biased towards a closed position in which it is in engagement with a non-return valve seat defined in the valve and adapted to move against said bias to an open position on flow of fluid through the valve from the inlet chamber to the outlet chamber.

8. A pressure control valve as claimed in claim 7 wherein the non-return valve closure member comprises a closure disc supported on a spindle slidable in a boss through a support member, the support member being fiz.ed relative to the outlet part and having at least one flow passage therethrough, the disc being capable of engaging said non-return valve seat to close the valve.

9. A pressure control valve according to any preceding claim wherein the passage, inlet chamber and outlet chamber are axially aligned.

10. A pressure control valve substantially as hereinbefore described with reference to either one of the accompanying drawings.