AU766691B2 - Pressure limiting valve - Google Patents

Description

-1- PRESSURE LIMITING VALVE FIELD OF INVENTION This invention relates to a pressure limiting valve, and in particular an in-line pressure limiting valve.

BACKGROUND

Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of common general knowledge in the field.

Pressure limiting or reducing valves are adapted to effect a reduction in pressure of a fluid passing through the valve, by automatic means, so that the outlet pressure is substantially constant irrespective of fluctuations in the inlet pressure.

Traditionally, pressure control valves have been reasonably bulky, particularly ••where the valve components have been oriented transverse to the flow. The 00o* development of coaxial or in-line pressure limiting valves has enabled such valves to be produced in a form which is less obtrusive in that the difference in diameter of the valve in comparison with that of the inlet and outlet portions is much less.

In order to provide more accurate control over outlet pressure, pressure limiting valves have included pressure-compensation systems. One such system is described in New Zealand Patent Specification No. 217527 which included a central passageway through the valve member to provide equal and opposite inlet pressures on either side of the valve member. The valve member is therefore only responsive to fluctuations in outlet pressure. Such pressure compensation systems add complexity to the valve.

Another factor which influences the efficiency of a pressure limiting valve is the extent to which the valve enables substantially coaxial flow of fluid through the valve.

The greater the disturbance to that coaxial flow the less efficient the valve.

WO 00/43700 PCT/NZ99/00226 2 The valve sealing component in most valves includes a washer which is secured to the valve seat by means of a centrally positioned securing means. Even where the washer is recessed into the washer holder, this still provides an opportunity for fluid, under pressure, to be forced behind the washer around the peripheral edges. The problems which result include damage to the washer, and a tendency to produce unacceptable noise, such as whistling. This can be a particular problem in pressure limiting valves including pressure compensation systems.

A further problem or complexity, associated with known pressure limiting valves concerns the method of assembly of these valves. New Zealand Patent Specification No. 223946 discloses a pressure limiting valve having three main parts, an inlet portion, a mid-portion and an outlet portion. The valve seal forms a part of the inlet portion, whilst the valve member is engaged within the mid-portion between the inlet portion and the outlet portion. Not only does this require three interconnecting parts, but also the valve sealing component must be assembled before the various components are interconnected, and is only accessible by disassembly.

New Zealand Patent Specification No. 217527 discloses a pressure limiting valve having only two main parts, with the inlet and outlet portions directly interconnected. However, again the jumper valve and valve seal must be completed and installed before interconnection of the two main parts, and are not accessible without disassembly.

It is an object of the present invention to provide a pressure limiting valve which reduces or overcomes at least some of the abovementioned problems, or which at least provides the public with a useful alternative.

Other objects of the invention may become apparent from the following description which is given by way of example only.

-3- SUMMARY OF THE INVENTION According to one aspect of the present invention there is provided a valve seal assembly for a pressure limiting valve, said valve seal assembly including a support member and sealing means in the form of a cup washer engaged on the support member by engagement means, said engagement means engaging the sealing means by peripheral portions only.

Preferably, the engagement means includes a retaining ring adapted to form a tight engagement of the peripheral wall of the cup washer over the support member.

Preferably, the engagement means further includes spaced-apart legs projecting from the retaining ring such that when ends of the legs abut a surface the retaining ring is spaced apart from that surface by the legs.

Preferably, the support member includes a plurality of webs that extend from a support surface for the cup washer, the webs defining a fluid communication path to the periphery of the valve seal assembly.

According to a further aspect of the present invention, there is provided a pressure limiting valve including an outlet and an inlet region, the valve seal assembly as described in the preceding paragraphs located between said outlet and inlet regions and a valve member co-operable with the valve seal assembly to open and close the pressure limiting valve, the valve member including a valve body defining a central bore having an internal profile which facilitates fluid flow through the valve member.

°Preferably, said inlet region is in fluid communication with said spaced-apart legs S and said valve member is movable to open and close a fluid communication path "between said spaced-apart legs and said outlet region.

Preferably, the webs of the support member are located within a fluid communication path from the inlet region to the periphery of the valve seal assembly.

-4- Preferably, the valve body includes an internal shoulder region between the outlet and inlet regions and said internal shoulder has a curved and/or smooth surface.

According to a further aspect of the present invention, there is provided a pressure limiting valve of co-axial or in-line type including an inlet chamber, an outlet chamber, a valve seal assembly in the inlet chamber, a moveable valve member into and out of contact with sealing means of the valve seal assembly, and wherein the sealing means is in the form of a cup washer engaged to a support member of the valve seal assembly by engagement means engaging peripheral portions of the sealing means only.

Preferably, the engagement means includes a retaining ring adapted to form a tight engagement of the peripheral wall of the cup washer over the support member.

Preferably, the engagement means further includes spaced-apart legs projecting from the retaining ring such that when ends of the legs abut a surface the retaining ring is spaced-apart from that surface by the legs.

Preferably, the spaces between the legs of the engagement means form the port.

According to a further aspect of the present invention there is provided a pressure limiting valve substantially as herein described and with reference to Figures 1 to 3 or Figure 4 of the accompanying drawings.

According to a further aspect of the present invention there is provided a valve member substantially as herein described with reference to the accompanying drawings.

*.**.According to a further aspect of the present invention there is provided a valve seal assembly substantially as herein described with reference to the accompanying drawings and/or examples.

S* Other aspects of the present invention may become apparent from the following description which is given by way of example only and with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 shows a cross-sectional view of a valve according to the invention in one preferred form, in a closed configuration; Figure 2 shows a cross-sectional view of the valve of Figure 1 in an open configuration; Figure 3 shows an exploded view of a valve assembly of Figures 1 and 2;

C

/o co WO 00/43700 PCT/NZ99/00226 6 FIGURE 4 shows a cross-sectional view of a valve of the invention in an alternative embodiment, in an open configuration.

DETAILED DESCRIPTION OF THE DRAWINGS With reference to the Figures, a valve 1 of the present invention includes an inlet body 2, an outlet body 3, a jumper valve 4 and a valve seal assembly The inlet body 2 includes inlet port 6, inlet chamber 7 and jumper valve support surface 8. A recess 9 is included in the bore of the inlet body 2 to accommodate a spring clip 10 adapted to retain the valve seal assembly 5 in the inlet body 2 in an assembled valve. A second recess 11 is included in the jumper valve support surface 8 to accommodate an O-ring 12 for sealing engagement between the jumper valve 4 and the jumper valve support surface 8.

The outlet body 3 includes an outlet port 15, an outlet chamber 16 and outer wall portion 17 adapted at the end 18 to engage with the inlet body 2 (for example by screw thread). Spring chamber 19 is formed between the outer surface of a front part 20 of the inlet body, and the internal surface of the outer wall portion 17 of the outlet body 3. The spring 22 (in Figure 3) is not shown in Figures 1 and 2.

An air vent 14 is provided through the outer wall portion 17 to facilitate movement of the jumper valve 4.

In a mid-portion of the outlet body 3, a recess 23 in the wall of the outlet chamber 16 is adapted to accommodate an O-ring 24 to form sealing engagement between the jumper valve 4 and the wall of the outlet chamber 16.

The valve seal assembly 5 has a base portion 30 adapted to form a snug engagement within the inlet body 2, a central member 31, a washer support surface 32, a washer 33 and a washer retaining ring WO 00/43700 PCT/NZ99/00226 7 34. The central member 31 may, for example, be formed from a series of veins or webs 39 radiating from a central axis, each web 39 connecting the base portion 30 with the washer support surface 32.

The webs 39 can be seen in Figure 3. In that embodiment there are 6 webs, but more or less could be included. The washer 33 is a "cup" washer which fits over the washer support surface 32. Washer retaining ring 34 engages over the peripheral sides 35 of the washer 33, securely engaging it on the washer support surface 32.

The washer retaining ring 34 as best seen in Figure 3, includes legs 36 extending from one side of the ring. In an assembled valve the ends 37 of the legs 36 abut against a stop 38 formed by an end portion of the inlet chamber 7.

It will be appreciated that the valve seal assembly enables sealing engagement of the washer 33 on the washer support surface 32 without the need for any central hole in the washer, and excluding any access of fluid around the periphery of the washer, which with conventionally secured washers results in damage to the washer and/or unacceptable noise levels, such as a whistling noise.

The jumper valve 4 includes valve seat 40, internal shoulder portions 41, outlet extension 42, and lateral extension 43. The lateral extension 43 extends outwardly from the main body of the jumper valve to form outer shoulder portion 44, which in an assembled valve is in the outlet chamber 16. Outer portion 45 of the lateral extension 43 is substantially parallel to but spaced-apart from the main body of the jumper valve 4 and has a buttress-type end 46 which, in use, engages against the spring 22. Thus, the lateral extension 43 forms a "skirt" for the jumper valve 4.

The jumper valve 4 has a compact form and the seals required in an assembled valve to ensure that the spring chamber 19 remains dry O-rings 12, 24) are relatively close together in terms of their longitudinal position in the valve. This enables the whole valve 1 to be produced in a relatively compact form. The valve member contacts an WO 00/43700 PCT/NZ99/00226 8 inner wall of the inlet body, at jumper valve support surface 8, and the internal sides of the outlet port 15, via outlet extension 16. This results in two longitudinally spaced-apart points of contact that provide axial stability to the valve member. The outer portion 45 of the "skirt" of the jumper valve 4, provides additional stability to the jumper valve 4 (i.e.

inhibiting tilt).

It will be appreciated that axial stability may also be provided where the o-rings 12, 24 are sufficiently separated longitudinally, and the jumper valve 4 is sufficiently long to extend over both seals.

To assemble a valve 1, of the invention, the jumper valve 4 is positioned in the outlet chamber of the outlet body 3 and the inlet body 2 is then engaged with the outlet body 3. The valve seal assembly may then be slid into the inlet port 6 of the assembled valve and secured in position by the spring clip 10. Thus, the body of the valve, including the jumper valve, can be fully assembled prior to introduction of the valve seal assembly. Furthermore, the valve seal assembly can be manufactured separately, if necessary. An added benefit of this design is that, with a suitably selected, removeable, spring clip 10 the valve seal assembly may be replaceable without the need to disassemble the valve.

An alternative assembly of a valve 1 of the invention is shown in Figure 4. This assembly differs from the embodiment of Figure 1 in that the inlet body 2 is formed in two parts, an inner portion 60 and an outer portion 61. This enables the valve 1 to be employed with different inlet ports 6. This embodiment differs from the embodiment of Figure 1 also in that the valve seal assembly 5 is retained in the inlet body 2 by a shoulder 62 in the outer portion 61, rather than by a spring clip 10. The assembly of a valve 1 in this modified form is also different in that the valve seal assembly 5 is first engaged in the inner portion 60, the outer portion 61 is then engaged with the inner portion 60, securing the valve seal assembly 5 in position, the jumper valve 4 is then positioned in the outlet chamber of the outlet body 3 and the formed inner body 2 is engaged with the outlet body 3.

WO 00/43700 PCT/NZ99/00226 9 Operation of a valve as the present invention will now be described, with particular reference to Figures 1 and 2.

It will be appreciated that the jumper valve 4 is movable in an axial direction between a closed position (as shown in Figure 1) in which the valve seat 40 contacts the washer 33, to prevent the flow of fluid from the inlet chamber 7 to the outlet chamber 16, and an open position (as shown in Figure 2) in which the valve seat 40 of the jumper valve 4 is spaced apart from the washer 33 to allow fluid flow from the inlet chamber 7 to the outlet chamber 16 via opening The spring 22 provides a bias maintaining the jumper valve 4 in the open position. The internal profile of the jumper valve including the internal shoulder portions 41 and outlet extension 42 facilitate the flow of fluid through the valve with minimal disturbance. This is also facilitated by the shape of the inlet chamber. The direction of fluid flow is, at worst, at 900 to axial flow no double back), thereby reducing any restriction of fluid flow.

The buttress type end 46 of the "skirt" of the jumper valve engaging with an internal shoulder 49 of the outer wall portion 17 of the outlet body 3 provides a stop for the jumper valve 4. This feature ensures that a gap 51 is maintained between the outer shoulder portion 44 of the jumper valve 4 and the opposing face 52 of the outlet chamber 16. Thus, fluid in the outlet chamber 16 acts on the outer shoulder portion 44 whether the jumper valve 4 is open or closed.

Other areas of the jumper valve 4 also are subject to a closing force from the outlet fluid pressure, including the shoulder portions 41 and outer rim 53. If the fluid pressure in the outlet chamber increases such that the force on these surfaces of the jumper valve 4 exceed a predetermined level (determined by the force applied by the spring to maintain the jumper valve 4 in an open position), then the jumper valve 4 will close to shut off the supply of fluid. Once the outlet pressure has declined to a sufficient level the valve will open as the force applied by the spring overcomes the return force on the exposed surfaces of the jumper valve 4.

WO 00/43700 PCT/NZ99/00226 The valve is designed to control pressure in the outlet chamber, and therefore to be sensitive to pressure changes in the outlet rather than the inlet. This is achieved in the present valve without the need for a pressure compensation system, by ensuring that there is no surface of the jumper valve 4 exposed to the inlet pressure in a way which would provide an axial force on the jumper valve 4. Thus, when the jumper valve 4 is in its closed position, as in Figure 1, the only surface exposed to the inlet chamber 7 is the end outer face 54 and there would be no force in an axial direction on this face.

With the jumper valve 4 in its open position the only force of the inlet pressure on the jumper valve 4 is on the inner rim 55. Any such force would be relatively insignificant in comparison with the force of the outlet pressure on the outer shoulder portions 44, internal shoulder portion 41 and outer rim 53.

Thus, a pressure limiting valve of the present invention enables the pressure limiting function, substantially governed by the outlet pressure only, without the need for a pressure compensation system. In its open position, the design of the valve facilitates axial flow of fluid through the valve. The design of the valve, and particularly that of the jumper valve, enables the valve to be produced in a compact form. The valve seat assembly ensures that fluid pressure cannot interfere with the positioning of the washer, to damage it or cause unacceptable noises.

Finally, in the embodiment of Figures 1-3 the body of the valve is formed from only two parts, and the valve as a whole is designed to be put together easily, with the valve seal simply engaged through the inlet of an otherwise assembled valve.

Where in the foregoing description reference has been made to specific components or integers of the invention having known equivalents then such equivalents are herein incorporated as if individually set forth.

WO 00/43700 PCT/NZ99/00226 11 Although this invention has been described by way of example and with reference to possible embodiments thereof it is to be understood that modifications or improvements may be made thereto without departing from the scope or spirit of the invention.

Claims (9)

1. A valve seal assembly for a pressure limiting valve, said valve seal assembly including a support member and sealing means in the form of a cup washer engaged on the support member by engagement means, said engagement means engaging the sealing means by peripheral portions only.

2. A valve seal assembly according to claim 1, wherein the engagement means includes a retaining ring adapted to form a tight engagement of the peripheral wall of the cup washer over the support member.

3. A valve seal assembly according to claim 2, wherein the engagement means further includes spaced-apart legs projecting from the retaining ring such that when ends of the legs abut a surface the retaining ring is spaced apart from that surface by the legs.

4. A valve seal assembly according to any one of claims 1 to 3, wherein the support member includes a plurality of webs that extend from a support surface for the cup washer, the webs defining a fluid communication path to the periphery of the valve seal "'assembly. a.o. A pressure limiting valve including an outlet and an inlet region, the valve seal assembly of any one of claims 1 to 3 located between said outlet and inlet regions and a valve member co-operable with the valve seal assembly to open and close the pressure limiting valve, the valve member including a valve body defining a central bore having 25 an internal profile which facilitates fluid flow through the valve member. a. o A pressure limiting valve according to claim 5 when dependent on claim 3 wherein said inlet region is in fluid communication with said spaced-apart legs and said valve member is movable to open and close a fluid communication path between said spaced- apart legs and said outlet region.

7. A pressure limiting valve according to claim 5 or claim 6, wherein the support member includes a plurality of webs that extend from a support surface for the cup 13 washer, the webs located within a fluid communication path from the inlet region to the periphery of the valve seal assembly.

8. A pressure limiting valve according to any one of claims 5 to 7, wherein the valve body includes an internal shoulder region between the outlet and inlet regions and said internal shoulder has a curved and/or smooth surface.

9. A pressure limiting valve of co-axial or in-line type including an inlet chamber, an outlet chamber, a valve seal assembly in the inlet chamber, a moveable valve member in the outlet chamber and a port between the inlet and outlet chambers, said port openable or closeable by axial movement of the valve member into and out of contact with sealing mean of the valve seal assembly, and wherein the sealing means is in the form of a cup washer engaged to a support member of the valve seal assembly by engagement means engaging peripheral portions of the sealing means only. A pressure limiting valve according to claim 9, wherein the engagement means includes a retaining ring adapted to form a tight engagement of the peripheral wall of the cup washer over the support member.

11. A pressure limiting valve according to claim 10, wherein the engagement means further includes spaced-apart legs projecting from the retaining ring such that when ends of the legs abut a surface the retaining ring is spaced-apart from that surface by the legs.

12. A pressure limiting valve according to claim 11, wherein the spaces between the legs of the engagement means form the port. A pressure limiting valve substantially as herein described and with reference to °Figures 1 to 3 or Figure 4 of the accompanying drawings. 30 14. A valve member substantially as herein described and with reference to the accompanying drawings. -14- A valve seal assembly substantially as herein described and with reference to the accompanying drawings. DATED this 25th Day of August, 2003. BALDWIN SHELSTON WATERS Attorneys for: METHVEN LIMITED ee o* b