NZ243920A - Pressure relief valve with tiltable closure - Google Patents

Description

Priority Datc(t): , t'\, -.1 , l ,4 i**;. .....

W i l|W 1 W I ^ «, |.< u J I ' > k' .1 v Class: /J.^.IIQ.1 Publication Daic: .. P.O. Joisrnd, No: -, i. -:: ,A3".'?;?9. j 2 6 MAY 1993 / 2k>^ „. i 2 ^ 3 9 A t' i ■5u»y Under the provisions of Regulation 23 (1) the C(?/npl&hz<>.

Specification has been ante-dated NEW ZEALAND 19 <3Q.

PATENTS ACT, 1953 Divided out of appln no. 235775 dated 23 October 1990 Initiate COMPLETE SPECIFICATION RELIEF VALVE WE, GSA INDUSTRIES (AUST.) PTY. LTD., of 51 Queen Street, Melbourne, Victoria 3000, Australia, a company incorporated under the laws of the State of Victoria, Australia hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- my =t *\\ 'a* O "RELIEF VALVE" This invention and/or that of NZ 235775 relates to relief valves and particularly such valves as used in hot water systems to relieve excessive pressure and/or temperatures as might develop in the system.

A problem with valves of the foregoing kind is that they do not always reseat properly after being opened. That is, when the valve closure member is lifted from the cooperative seat, it may be caused to tilt relative to the valve seat, and that tilted disposition may persist when the closure member is returned to engagement with the seat. In the absence of a substantial closing force on the valve, the tilted disposition of the closure may remain with consequent alteration of the opening pressure of the valve due to leakage past the valve seat.

The tilt problem is particularly prevalent in valves having a manual relief facility. In such valves, a lever is pivotally mounted on the valve body and is connected to the closure member so as to enable manual opening of the valve. Operation of that lever has a particular tendency to cause the closure member to tilt.

Valves of the foregoing kind are commonly provided with a vacuum break facility whereby the associated system can be connected to atmosphere in the event that sub-atmospheric pressure conditions develop within the system. Such vacuum break facilities have not been entirely satisfactory for a variety of reasons.

It is an object of the present invention to provide a relief valve of the foregoing kind which is less prone to ineffective closing than prior valves of the same kind. It is a further object of the invention in a preferred form to provide such a valve having an improved vacuum break facility.

A valve according to the invention is characterised in that the closure member is arranged so as to have at least limited freedom of tilting movement relative to the valve seat such that it will automatically adopt an effective closing disposition relative to the seat when engaged with that seat. That is, the closure member has U VJ - la the capacity to find an effective closing disposition relative to the seat independent of the influence of associated parts of a valve.

It is a further characteristic of the invention in a preferred form, that a vacuum break facility forms part of the closure member. Prior valves of the same kind generally have the vacuum break facility associated with or separate from the closure member, and Australian patent 490,713 discloses an example of such a prior arrangement.

According to an aspect of the present invention, there is provided a relief valve for use in a fluid system, including a valve body, an inlet chamber and a relief chamber formed within said body, an orifice through which said chambers communicate, a valve seat surrounding said orifice, a closure member mounted within said body for movement towards and away from said valve seat and being operable to engage said seat and thereby prevent said communication through the orifice, biasing means resiliently urging said closure member into engagement with said valve seat, and means connecting said closure member to said biasing means such that said closure member can tilt in any direction relative to the line of the force imposed on said closure member by said biasing means and thereby ensure effective engagement with said valve seat.

The expression "effective engagement" as used throughout the specification is to be understood as referring to engagement between the closing member and the valve seat which is such as to close the valve orifice and thereby prevent communication through that orifice. Also, the reference to the valve seat surrounding the orifice is intended to embrace situations in which the valve seat is formed by a surface of the orifice.

According to an aspect of the invention of NZ 235775, there is provided a relief valve for use in a fluid system, including a valve body, an inlet chamber and a relief chamber formed within said body, an orifice through which said chambers communicate, a valve seat surrounding said orifice, a closure member mounted within said body for movement towards and away from said valve seat and being operable to engage said seat and thereby prevent said communication through the orifice, and a vacuum break facility forming part of said closure member and which is operative to prevent the pressure in the inlet chamber falling substantially below the pressure existing in the relief chamber.

The attached drawings show an example valve incorporating an embodiment of the invention, and it is to be understood that the particularity of those drawings does not supersede the generality of statements made throughout this specification concerning the nature of the invention and of constructions which might embody the invention.

Figure 1 is a cross-sectional view of a typical pressure-temperature relief valve to which an embodiment of the invention is applied.

Figure 2 is an enlarged view of part of the arrangement shown in Figure 1.

Figure 3 is a view similar to Figure 1 but shows another embodiment of the invention.

Figure 4 is an enlarged view of part of the assembly shown in Figure 3.

Figure 1 of the drawings shows a temperature-pressure relief valve having a hollow body 1 arranged in a conventional manner. The interior of the body 1 is divided into an inlet chamber 2 and a relief chamber 3, and an inlet port 4 communicates with the inlet chamber 2 and a drain port 5 communicates with the relief chamber 3. The two chambers 2 and 3 communicate through an orifice 6, and a closure member 7 is operable to close that orifice 6 under normal operating conditions. Such closure is effected by the closure member 7 engaging against a seat 8 which surrounds the orifice 6.

A temperature responsive probe 9 of a known kind is connected to the valve body 1 and is arranged to press against the closure member 7 and lift that member 7 off the seat 8 in the event of excessive temperature conditions occurring within the associated system. When the temperature drops, the probe 9 allows the closure member 7 to return to a closed position. For that purpose, it is generally preferred that the closure member " \ 7 is biased towards the closed position by a coil compression spring 10, but other biasing means could be adopted.

In the particular arrangement shown, the closure member 7 is normally held against the valve seat 8 by a plunger 11 which forms part of the biasing means and is influenced by the spring 10. The plunger 11 can take any of a variety of forms, but in the arrangement shown it includes a stem 12 and a head section 13 connected to or formed integral with one end of that stem 12. Guide means may be provided to keep the plunger 11, and consequently the closure member 7 to a substantially straight path of movement. For that purpose, the stem 12 in the arrangement shown is slidably located within a sleeve 14 so as to be movable axially towards and away from the valve seat 8. The spring 10 acts between the sleeve 14, or another part of the valve body 1, and a lateral flange 15 of the head section 13.

A flexible diaphragm 16 may extend between the head section 13 and the surrounding wall of the body 1, as shown, so as to isolate the spring chamber 17 from the relief chamber 3.

It is preferred that the stem 12 is connected to the head section 13 through screw threaded engagement so as to permit adjustment of the overall length of the plunger 11. In the arrangement shown, the screw threaded connection includes an internal thread formed within a bore 18 extending axially through the head section 13, and an external thread on an end portion of the stem 12.

An important feature of the invention is the way in which the plunger 11 and the closure member 7 cooperate. In particular, the closure member 7 is attached to the plunger 11 through a swivel or universal-type joint so that the closure member 7 is capable of relatively free tilting movement relative to the axis of the plunger 11, at least over a limited range. Such freedom of movement enables the closure member 7 to automatically adopt a disposition which results in effective closing of the orifice 6.

In the particular arrangement shown, the foregoing requirement is achieved in the following manner.

The closure member 7 of the embodiment shown includes a circular plate section 19 and a short spindle projecting axially from one side of that plate section 19. It is a feature of the spindle 20 that an enlargement 21 is provided at the outer end portion, and that enlargement 21 is a loose sliding fit within a recess formed by an end of the bore 18 (Figure 2) of the plunger 11. The axial extent of the enlargement 21 is relatively short so as not to impede tilting of the spindle 20 relative to the axis of the plunger 11.

A closing force is applied to the closure member 7 by end to end engagement between the plunger stem 12 and the spindle 20. In the arrangement shown, the engaging end 22 of the stem 12 is shaped so as to have substantially point contact with the adjacent terminal end surface 23 of the spindle 20 and thereby allow relative tilting movement as referred to above. For that purpose, the stem end 22 may be of rounded (spherical) form as shown. Other arrangements could be adopted to achieve the same result. For example, the end surface 23 of the spindle 20 could be shaped instead of the stem end 22.

Any suitable means may be adopted to retain the spindle enlargement 21 within the bore 18 to prevent complete separation of the plunger 11 and the closure member 7.

In the particular arrangement shown, the valve seat 8 is formed by a flat end surface of a bush 23 secured within the body 1. The orifice 6 is also formed by that bush 23.

Sealing means is preferably provided on the closure member 7 for engagement with the seat 8, and in the arrangement shown (Figure 2) that includes a resilient O-ring 24 secured to the underside of the plate section 19. Any suitable means may be used to secure the O-ring 24, but in the arrangement shown, the O-ring 24 is secured between an axially extending wall 25 of the closure member 7 and a band 26 attached to that member 7. The wall 25 projects axially from the underside of the plate section 19, and an annular groove is defined between that wall 25 and the band 26. A lip 27 on the wall 25 projects towards a similar lip 28 on the band 26, and those lips 27 and 28 function to prevent escape of the O-ring 24 from the groove.

Any means may be adopted to connect the band 26 to the plate section 19. It is preferred that the connection is achieved by capturing an end portion of the plate section 19 between a shoulder 29 of the band 26 and a turned over portion 30 of the band 26 as shown in Figure 2.

It is preferred that the O-ring 24 is distorted as shown in Figure 2 so that a curved surface 31 is exposed for engagement with the valve seat 8. Under high closing pressure, that surface 31 may be flattened so that there is metal to metal contact between the closure member 7 and the bush 23.

The arrangement described has the advantage that the closure member 7 can freely tilt relative to the plunger 11 and thereby automatically adapt the plane of the valve seat 8. Effective closing of the valve is thereby ensured. Manual opening of the valve may be achieved by means of the lever 32 shown in Figure 1.

A vacuum break facility is preferably provided as part of the closure member 7. In the arrangement shown, that facility includes at least one opening 33 extending through the plate section 19, and a flexible annular disc 34 at the underside of the plate section 19 which is operable to close the or each opening 33. The disc 34 can be formed of silicone or other suitable material, and is captured against separation from the closure member by a stop cap 35. The cap 35 is preferably an interference fit over an axial projection 36 of the closure member 7 which passes through the central hole of the disc 34. It will be apparent that other arrangements could be adopted to attach the disc 34 to the closure member 7.

The disc 34 is a relatively loose fit on the projection 36 and is free to move axially along that projection 36 to a limited extent. Such an arrangement ensures that the disc 34 is able to move away from the% opening 33 with minimum difficulty and ensure communication between the chambers 2 and 3 when sub-atmospheric pressure conditions arise in an associated system. Return of the disc 34 to an opening closing condition is not inhibited for the same reasons.

The assembly shown in Figures 3 and 4 does not differ significantly from the assembly previously described. There are two major differences. One concerns the manner of adjusting the force of the spring 10, and the other is the manner of cooperation between the plunger 11 and the closure member 7.

In the Figure 3 arrangement, the sleeve 14 is of much reduced length and has an external thread which cooperatively engages with an internal thread 37 of the body 1. Axial adjustment of the sleeve 14 relative to the body 1 therefore adjusts the compression of the spring 10. With such an arrangement, an axial bore need not be provided through the plunger 11 as in the Figure 1 arrangement, and as best seen in Figure 4 the enlargement 21 of the closure member 7 locates within a recess 38 provided in the adjacent end of the plunger 11.

As shown in Figure 4, the end surface 23 of the spindle 20 is curved or part spherical so as to have a substantially point contact with the flat opposed surface 22 of the plunger 11. Other arrangements are clearly possible.

A suitable blow-out valve is provided in the opening 39 through the body 1 as shown in Figure 3, and that blow-out valve has been omitted for convenience of illustration.

It will be apparent from the foregoing description that a valve according to the invention has substantial advantages over similar prior valves. Closing of the valve is more certain because of the swivel attachment of the closure member to the spring biased plunger, and an efficient vacuum break facility is provided.

Various alterations, modifications and/or additions may be introduced into the constructions and arrangements of parts previously described without departing from the ambit of the invention as defined by the appended claims.

Claims (12)

^ WHAT-t/WE CLAIM IS: 2, 4 5 WHAT I CLAIM IG;'

1. A relief valve for use in a fluid system, including a valve body, an inlet chamber and a relief chamber formed within said body, an orifice through which said chambers communicate, a valve seat surrounding said orifice, a closure member mounted within said body for movement towards and away from said valve seat and being operable to engage said seat and thereby prevent said communication through the orifice, biasing means resiliently urging said closure member into engagement with said valve seat, and means connecting said closure member to said biasing means such that said closure member can tilt in any direction relative to the line of the force imposed on said closure member by said biasing means and thereby ensure effective engagement between said closure member and said valve seat.

2. A relief valve according to claim 1, wherein said connecting means comprises a swivel joint provided between said closure member and a plunger which forms part of said biasing means and is axially movable relative to said body.

3. A relief valve according to claim 2, wherein said swivel joint includes an end portion of said closure member and an axial recess of said plunger within which said end portion is a sliding fit, and said end portion has a relatively short axial length so as not to impede tilting movement of said closure member relative to said plunger.

4. A relief valve according to claim 3, wherein there is substantially point contact between a terminal surface of said end portion and an opposed surface of said plunger.

5. A relief valve according to claim 4, wherein either said terminal surface or said opposed surface is a part spherical surface.

6. A relief valve according to any one of claims 2 to 5, wherein said plunger is spring influenced so as to maintain an orifice closing bias on said closure member.

7. A relief valve according to any one of claims 3 to 6, wherein said closure member includes a circular plate section and a spindle extending axially from one side of that plate section, and said end portion is an end portion - 9 - of said spindle which is remote from said plate section and which is formed by a radial enlargement of said spindle. — \

8. A relief valve according to any preceding claim, wherein said closure member includes a vacuum break facility which is operative to prevent the pressure in the inlet chamber falling substantially below the pressure existing in the relief chamber.

9. A relief valve according to claim 8, wherein said vacuum break facility forms part of said closure member.

10. A relief valve according to claim 8 or 9, wherein said vacuum break facility includes at least one opening extending through the closure member such as to provide communication between the two said chambers, and a flexible element mounted on the side of the closure member adjacent the inlet chamber and being responsive to the pressure differential between said chambers so as to close or open said opening according to the nature of said pressure differential.

11. A relief valve according to claim 10, wherein said flexible element is an annular disk attached to said closure member and which is capable of limited axial movement relative to that member.

12. A relief valve substantially as herein particularly described with reference to what is shown in the accompanying drawings. 9592k A.J DATED THIS DAY OF A. J. PARK & SON. S) pER A3ENTS FOR THE APRJ CANTS I : ■ >, / - 10 -