NZ217527A - Pressure control valve: balanced pressures on shuttle when closed - Google Patents

Description

217527 r i>.

Priority Date(s): ...l).-°l.:Z5.

Complete Specification Filed: /P. ~^TjS$? Class: . ..../fZ^/.7/PP Publication Date: . ...a.Q.MAYJM'....

P.O. Journal, No: ^ rjosEPttft i 4 A •i F Patents Form No. 5 NEW ZEALAND PATENTS ACT 19 53 COMPLETE SPECIFICATION "PRESSURE CONTROL VALVE" X, WE ACTROL INDUSTRIES PTY. LTD, a company incorporated under the laws of the State of Victoria, Australia, BHP House, 140 William Street, Melbourne, Victoria, 3000, AUSTRALIA, hereby declare the invention, for which I"/we pray that a patent may be granted to ta<5/us, and the method by which it is to be performed, to be particularly described in and by the following statement 217527 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. Some valves of that kind are used as proportioning valves in that they are intended to provide a particular output pressure which has a fixed relationship to the input pressure. The problem with many valves of that kind is that the output pressure tends to vary in accordance with variation in the input pressure and as a consequence they do not always function as intended.

It is an object of the present invention to provide a control valve of the foregoing kind which is of relatively compact and simple construction. It is a further object of the invention to provide such a valve which is operable to provide a substantially constant output pressure. That is, the output pressure of the valve is not affected by variations in the input pressure.

A valve according to the present invention may take any one of several forms, but it will be convenient to hereinafter describe the invention with reference to one particular form which is very compact.

According to one aspect of the present invention, there is provided a pressure control valve including, a hollow body, two chambers formed within said body, two ports each of which communicates with a respective said chamber and through which fluid can move into and out of that chamber, an orifice within said body through which said chambers communicate, a valve member mounted within said body for movement relative thereto towards and away from a position at which it closes said communication through said orifice, a biasing spring urging said valve member away from said communication closed position, said valve member being responsive to fluid pressure within one of said chambers so as to be movable into the communication closed position against the influence of said spring, and passage means permitting fluid pressure within the AT 2 1752 7 other said chamber to impinge on each of two oppositively facing aides of the valve member, each said side faces generally in a respective one of the two directions of movement of said valve member, and the arrangement is such that the area of each said side against which said pressure impinges is substantially the same when the valve member is in said communication closed position and is different when the valve member is not in that position.

According to a further aspect of the invention, there is provided a pressure control valve including, a hollow body formed of two parts, one said part including a tubular barrel section which is located within the other said part, two chambers formed within said body, one of said chambers being formed within said other part and the other said chamber being formed at least in part by the bore of said barrel section, a port in each said part which communicates with the chamber of the respective said part and through which fluid can move into and out of that chamber, an orifice at the inner end of said barrel section through which said chambers communicate, a valve member mounted within said body for movement relative thereto towards and away from a position at which it closes said communication through the orifice, and a coil compression biasing spring located around said barrel section and acting between said valve member and said one part so as to urge said valve member away from said communication closed position.

Embodiments of the invention are described in detail in the following passages of the specificaton which refer to the accompanying drawings. The drawings, however, are merely illustrative of how the invention might be put into effect, so that the specific form and arrangement of the various features as shown is not to be understood as limiting on the invention. In the drawings: Figure 1 is a cross-sectional view of a valve according to one embodiment of the invention, Figure 2 is a cross-sectional view of part of the valve shown in Figure 1 and showing the valve in an open condition, Figure 3 is a cross-sectional view of a valve according to another embodiment of the invention, Figure 4 is a cross-sectional view of a valve according AT -3- 2 1 7527 to still another embodiment of the invention, Figure 5 is an enlarged cross-sectional view of part of the valve shown in Figure 4 and showing the valve in a closed condition, Figure 6 is a view similar to Figure 5 but showing the valve in the initial stages of opening movement.

In the example valve shown in figure 1 of the drawings, the inlet port 1, outlet port 2 and valve controlled orifice 3 are arranged in line, but such an arrangement is not essential. The valve body 4 is formed of two parts 5 and 6 which may be conveniently referred to as inlet and outlet parts 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. For example, at least some aspects of the outlet part 6 as hereinafter described may be adopted at the inlet side of a valve incorporating the invention.

The outlet part 6 as shown is of generally tubular form and has connecting means 7 at one end whereby that part 6 can be secured to say the end of a length of conduit. That connecting means 7 may be of any suitable type and may include an internal or external screw thread. An outlet passage 8 is formed through the end portion of the outlet part 6 which includes or forms the connecting means 7, and as shown that passage is preferably of smaller cross-sectional size than the bore 9 which forms the interior of the main portion of the outlet part 6. The outlet passage 8 and the bore 9 are preferably coaxial as shown.

The inlet part 5 may also be of tubular form and in the particular arrangement shown has a tubular barrel section 10 and a connecting section 11 extending axially from respective opposite ends of a mounting section 12. The mounting section 12 is adapted to cooperate with the outlet part 6 of the valve body 4 so as to secure the two parts 5 and 6 together. The barrel section 10 extends into the outlet part 6 for a reason hereinafter made clear, and the connecting section 11 is preferably located external of the outlet part 6 for connection - e.g., through cooperating threads - with a AT 217527 conduit or other member. The bore 13 which extends axially through the inlet part 5 may be enlarged as shown at the end portion 14 thereof remote from the outlet part 6.

It is preferred, as shown, that the mounting section 12 is located within the end portion of the outlet part 6 which is remote from the connecting means 7 of that part 6. An external thread on that section may cooperate with an internal thread of the outlet part 6 to releasably hold the two parts 5 and 6 against separation. The barrel section 10 projects axially into the bore 9 of the outlet part 6 and has an external diameter and length such that an annular space 15 is provided between it and the surrounding surface of the bore 9 and its terminal inner end 16 (figure 2) is axially spaced from the shoulder 17 formed at the junction of the bore 9 and the outlet passage 8.

As shown, the mounting section 12 may be arranged so that it extends across an end portion of the barrel section 10. In the example shown, a portion 18 of the mounting section 12 is in the form of a sleeve which surrounds the aforementioned end portion and is located radially outwards therefrom. The arrangement is such that an annular cavity 19 is formed between the mounting and barrel sections 12 and 10 and that cavity 19 serves a function as hereinafter described.

A valve member 20 is located between the terminal end 16 of the barrel section 10 and the outlet passage 8 and, as shown, is preferably supported at opposite end portions by the barrel section 10 and a support member 21 respectively. The support member 21 may be located within the outlet part bore 9 so as to abut against the shoulder 17 formed at the junction of that bore 9 and the outlet passage 8. A circlip 22 or other securing means may be employed to hold the member 21 against movement away from that abutting relationship. The support member 21 shown includes a core section 23 which has a cylindrical cavity 24 extending partway therethrough from the end 25 which faces towards the barrel section 10, and that cavity 24 is preferably substantially coaxial with the barrel section 10. It is also preferred that the diameter of the cavity 24 is substantially the same as that of the bore 13 of the barrel section 10. A plurality of passages 26 are located AT 2175.27 around the core section 23 and extend completely through the support member 21 to provide communication between the outlet passage 8 and the bore 9 of the outlet part 6.

In the particular arrangement shown, a chamber 27 surrounding the valve member 20 forms an outlet chamber, and the bore 13 of the barrel section 10 forms an inlet chamber 28. The chambers 27 and 28 communicate through the orifice 3 except when the valve member 20 is in the communication closed position as shown in figure 1 at which it closes the orifice 3.

One end portion 29 of the valve member 20 is slidable axially within the core section cavity 24 and a resilient O-ring 30 or other sealing means may be provided on that end portion 29 to provide substantial fluid sealing engagement with the cavity 24. If desired, the end portion 29 of the valve member 20 may be partially spherical as shown or otherwise formed so that the valve member 20 is capable of limited lateral tilting movement relative to the support member 21 without disturbing the aforementioned sealing engagement.

An opposite end portion 31 of the valve member 20 may be slidably located on the terminal end portion of the barrel section 10 as shown. That is, a bore 32 is formed within that end portion 31 to slidably receive the barrel section 10. A valve seating portion 33 (figure 2) is provided at the inner end of that bore 32 to engage a valve seat 34 formed around the orifice 3. In the arrangement shown, the valve seat 34 is formed by the end 16 of the barrel section 10. Also in the arrangement shown, the seating portion 33 includes an annular member 35 of resilient material secured against a transversely extending surface formed at the inner end of the bore 32. A passage 36 extends through the seating portion 33 and the adjacent end portion 29 of the valve member 20 so as to provide communication between the cavity 24 and the chamber 28.

Part of the valve member end portion 31 which receives the barrel section 10 may be enlarged as shown to form a piston-like element 37. That piston element 37 slidaj engages the surrounding surface of the outlet part bore^^QffiS that engagement may be effected through a resilient O-fPing 38 -z- AT -6- 217527 or other suitable sealing means. The same or similar sealing means 39 may be provided between the valve member end portion 31 and the surface of the barrel section 10 over which it slides. Assuming an O-ring is used in each case as shown, those 0-rings 38 and 39 may be in substantial transverse alignment so as to assist in keeping the axial length of the valve member 20 to a minimum.

A plurality of transfer ports 40 are provided in the valve member 20 at a location between the seating portion 33 and the piston element 37. Each port 40 provides communication between the orifice 3 and the chamber 27 when the valve member 20 is in the open position as shown in figure 2.

It is preferred that the terminal end 16 of the barrel section 10 is chamfered or otherwise formed to provide an annular valve seat 34 of relatively small area for engagement with the seating element 35. A biasing spring 41 acts between the valve member 20 and the valve body 4 so as to normally urge the seating element 35 away from the valve seat 34. In the preferred arrangement shown, that spring 41 is a helical compression spring which is located around the barrel section 10 and extends into the annular cavity 19 to engage the base of that cavity 19. Location of the spring 41 within such a cavity 19 enables a significant reduction in the overall length of the valve. At least one air bleed passage 60 may be provided through the valve body 4 to connect atmosphere with the space 15 containing the spring 41 and thereby avoid generation of high pressure or vacuum conditions within that space 15.

A valve as described above operates in the following manner. It will be assumed that the pressure to be controlled is the fluid pressure on the outlet side of the valve and the valve is at a stable condition such that the seating element 35 is engaging against the valve seat 34 of the barrel section 10. Under those circumstances, the inlet fluid pressure of the chamber 28 acts against so much of the valve member 20 as is exposed within the barrel section 10 and it against the back surface 42 of the valve member within the support member 21 because of the passage AT • • 217527 the valve member 20. Since the cavity 24 and the bore 13 are joined by the passage 36, the same fluid pressure acts against the two oppositely facing sides of the valve member 20, but that pressure does not tend to cause axial movement of the valve member 20 because the area exposed to the pressure is substantially the same on each side of the valve member 20. That arises because the cavity 24 and the bore 13 are of substantially the same diameter.

Fluid pressure existing on the outlet side of the valve imposes a closing force on the valve member 20 because of the surface areas of that member 20 which are exposed to the outlet chamber 27. In particular as shown, the piston element 37 provides a relatively large surface area against which the outlet pressure acts so that the valve member 20 is urged toward the barrel section 10. That closing influence is counter balanced at least in part by the biasing spring 41 acting on the valve member 20, and the force of that spring 41 may be predetermined to suit particular conditions of use of the valve.

When the outlet pressure falls below a certain level the biasing spring 41 operates to push the valve member 20 away from the barrel section 10 and thereby allows the relatively high inlet pressure to extend across the full face of the seating portion 33 as shown in figure 2. Inlet fluid is then able to pass through the transfer ports 40 in the valve member 20 to enter the outlet chamber 27. The outlet side pressure is thereby increased until it is again sufficiently high to overcome the influence of the biasing spring 41, at which time the valve closes.

The foregoing operation is repeated from time to time as necessary to maintain the outlet pressure at or near the desired level.

Figure 3 shows a valve similar to that of figures 1 and 2, and components of that embodiment which correspond to components of the figure 1 embodiment will be given like reference numerals except that they will be in the number series 100 to 199. The figure 3 valve differs from that of figure 1 in the following respects.

The valve member 120 is supported by a flexible AT -8- 217527 diaphragm 159 rather than being slidable within the bore 109. The diaphragm 159 is arranged to allow adequate axial movement of the valve member 120 and is clamped between two separable sections 143 and 144 of the valve body part 106. It will be obvious that the particular construction shown is open to substantial variation.

Furthermore, the figure 3 valve omits a support member as shown in figure 1 and includes instead an inwardly projecting finger 145 which is formed as an integral part of the body section 143. The cylindrical cavity 124 is formed in that finger 145 as shown. Obviously, the same variation could be adopted in the figure 1 construction.

The figure 3 valve also includes a one-way flow facility 146 to prevent back-flow through the inlet port 101. For that purpose, the valve body 104 includes another section 147 which contains the inlet port 101 and inlet passage 114. A spring influenced valve jumper 148 is arranged to engage against a seat 149 formed within that section 147 so as to automatically close if the fluid pressure in chamber 128 exceeds that at the inlet port 101. The stem 150 of the jumper 148 is slidably located in the core 151 of a support spider 152 having passages 153 extending therethrough, and a spring 154 acts between that spider 152 and the head 155 of the jumper 148. Once again, such a modification could be adopted in the figure 1 construction.

Figures 4 to 6 show yet another embodiment in which the main dinstinction is in the nature of the seating arrangement of the valve member. Components of the figure 1 embodiment which are similar to components of the figure 1 construction will be given like reference numerals but which are in the number series 200 to 299.

The valve seat 234 of the figure 4 construction is formed by a frusto-conical surface as best seen in figure 6, and the opposed surface of the valve member seating portion 233 is of complementary shape. A resilient O-ring 235 is carried by the valve member 220 and is arranged to be engaged with the valve seat 234.

In the particular construction shown, the O-ring 235 is retained in place by being captured between two parts of the c ' AT -9- 217527 valve member 220. The groove for retaining the O-ring 235 is formed by opposed surfaces of the main body of the valve member 220 and a tubular insert 256, and that insert 256 also forms part of the seating portion 233. It is preferred that the O-ring 235 projects slightly beyond the surface of the seating portion 233 when in a relaxed "non-compressed" condition as shown in figure 6.

When the valve of figure 4 is in the closed condition as shown in figures 4 and 5, the O-ring 235 is compressed so that the seating portion 233 and valve seat 234 engage. As a consequence fluid pressure in the chamber 228 acts over an area of the valve member 220 defined by a circle having a diameter "d" (figure 5). During an initial part of opening movement of the valve, the O-ring 235 is freed to expand towards its natural relaxed shape as shown in figure 6. As that expansion takes place, the valve member 220 moves away from the valve seat 234, but escape of fluid across the valve seat 234 is prevented by the continued engagement between that seat 234 and the O-ring 235.

In spite of the fact that the valve is effectively closed under the figure 6 condition, fluid pressure within the chamber 228 is now able to impinge against a larger area of the valve member 220. That larger area is defined by the circle of diameter "D" as shown in figure 6. Such an increase in the exposed area of the valve member 220 produces a pressure imbalance between the opposite sides of that member such that it is positively urged into the open condition by a force additional to that imposed by the spring 241. The valve member 220 is thereby pushed beyond the position shown in figure 6 to allow fluid from the chamber 228 to escape through the orifice 203 and transfer ports 240 into the chamber 227.

A pressure imbalance situation as described above also arises, momentarily, in the constructions of figures 1 and 3, but with perhaps less effect than in the figure 4 construction. In the figure 1 and 3 constructions, fluid pressure within the chamber 28,128, impinges against a larger area of the inlet side of the valve member 20,120, when the valve commences to open. The opening influence of the resulting pressure imbalance on the valve member 20,120, is AT 7527 quickly diminished, however, because there is nothing to prevent rapid exhaust of fluid into the chamber 27,127.

Figure 4 also shows the possibility of locating the O-rings 238 and 239 otherwise than on the valve member 220.

A valve as described has several advantages over prior valves of the same general kind. For example, the control or inlet pressure does not act against a spring, but acts against the influence of the pressure which it is intended to control. A much more accurate level of control is therefore possible. Also, the particular arrangement described is ' ' extremely compact and one factor contributing to that result is the telescoped nature of the valve body and biasing spring. Yet another advantage is the pressure imbalance which acts on the valve member during initial opening movement so as to positively aid that opening movement. Other advantages and "") features will be apparent to people skilled in the relevant art. -t Various alterations, modifications and/or additions may be introduced into the constructions and arrangements of parts previously described without departing from the spirit or < ambit of the invention as defined by the appended claims. «v < -3 Vj AT 21753V

Claims (21)

WHAT WE CLAIM IS:

1. A pressure control valve including, a hollow body, two chambers formed within said body, two ports each of which communicates with a respective said chamber and through which fluid can move into and out of that chamber, an orifice within said body through which said chambers communicate, a valve member mounted within said body for movement relative thereto in either of two directions so as to be movable towards and away from a position at which it closes said communication through said orifice, a biasing spring urging said valve member away from said communication closed position, said valve member being responsive to fluid pressure within one of said chambers so as to be movable into the communication closed position against the influence of said spring, and passage means permitting fluid pressure within the other said chamber to impinge on each of two oppositely facing sides of the valve member, each said side faces generally in a respective one of the two directions of movement of said valve member and is arranged such that the area of each said side against which said pressure impinges is substantially the same when the valve member is in said communication closed position and is different when the valve member is not in that position, the other said chamber is formed at least in part by the bore of a tubular barrel section, said orifice is located at one end of said barrel section, said spring is a coil compression spring which acts between said Valve member and said body and which is arranged substantially coaxial with said barrel section, and at least part of said spring is located around said barrel section.

2. A valve according to claim 1, wherein said hollow body is formed of two parts, one said part includes said tubular barrel section and that said section is located within the other said part, and said one chamber is formed within said other part. -■ < ^ Qi

3. A valve according to claim 1 or 2, wherein saidv'ports /: T are arranged substantially coaxial with said barr^X-* section^ bore. 1;"^ ^

4. A valve according to any preceding claim,v. wherein, passage means is provided to permit fluid pressure within "said other chamber to impinge against each of said two sides of the 3 • 217527 valve member.

5. A valve according to any preceding claim, wherein a valve seat surrounds said orifice and said valve member engages said valve seat to effect said communication closed posi t ion.

6. A valve according to any preceding claim, wherein said valve member is slidably mounted on an end portion of said barrel section.

7. A valve according to claim 6, wherein said valve member ^ includes an annular piston portion which is slidably located ^ within an annular space formed between an outer surface of said barrel section and a wall of said body which surrounds that section.

8. A valve according to claim 6 or 7 when appended to claim 4, wherein a piston portion of said valve member is slidably located within a cylindrical cavity provided within said body, said cavity is closed at one end by an end surface extending transverse to the axis of the cavity, a terminal end surface of said valve member end portion is arranged in opposed relationship to said end surface, a space is formed between the two said end surfaces, and said passage means provides communication between that space and said other chamber.

9. A valve according to claim 8, wherein said cavity is formed within a support member which is located within said body between said one chamber and the said port communicating with that chamber, and at least one passage is formed through said support member to provide said communication between said one chamber and the respective said port.

10. A valve according to claim 8 or 9, wherein said cavity is substantially coaxial with said orifice and with said port which communicates with said one chamber.

11. A valve according to any one of claims 8 to 10, wherein said piston portion is formed by an end portion of said valve member which is opposite to the end portion thereof located within said barrel section, and a seating portion of said valve member is located between said end portions and is arranged to engage an end of said barrel section to thereby close said communication through said orifice. / ^

12. A valve according to claim 11, wherein said/ seating m . — £*-"NC* -u- 217557 portion includes a resilient member which is engageable with said barrel section end.

13. A valve according to claim 11 or 12, wherein at least one transverse port is formed through said valve member at a location between said seating portion and said piston portion to permit communication between said orifice and said one chamber when said valve member is not in said communication closed position.

14. A valve according to any one of claims 8 to 13, wherein the diameter of said barrel section bore is substantially the same as the diameter of the said cavity in which the valve member piston portion is located.

15. A valve according to any one of claims 1 to 11, wherein a resilient annular element is compressed between said valve member and portion of said body when the valve member is in said communication closed position, said annular element is arranged to expand from said compressed condition during an initial part of movement of said valve member away from said communication closed position, the communication between said chambers remains closed as said annular element expands, and the area of said valve member exposed to fluid pressure within said other chamber increases as a consequence of said initial part of the valve member movement.

16. A valve according to claim 15 when appended either directly or indirectly to claim 5, wherein said valve seat is frusto-conical and said resilient element is located so as to project beyond a substantially complementary frusto-conical surface of said valve member.

17. A valve according to claim 16, wherein said resilient element is arranged to engage said frusto-conical surface at a location between the larger and smaller diameters thereof.

18. A valve according to claim 1, wherein the two said ports are substantially coaxial.

19. A valve according to any preceding claim, wherein said area difference is such that the resulting differential in pressure from said other chamber acting across said valve member tends to urge said valve member away from said communication closed position. o^

20. A valve according to any preceding claim, wherein said ^ If*?' >C f ^ 217527 ports constitute inlet and outlet ports respectively, said other chamber constitutes an inlet chamber and is connected to said inlet port, and said one chamber constitutes an outlet chamber and is connected to said outlet port.

21. A pressure control valve substantially as herein particularly described with reference to any one of the embodiments shown in the accompanying drawings. o Av c e