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    • 专利摘要:
    Abstract A valve 1 comprising a body 2, an inlet 4 for fluid to enter the body 2, an outlet 6 for fluid to exit the body 2, a piston member 8 moveable within the body 2, and a spring 10 located in a spring chamber 73 to bias the piston member 8 in a first direction D, and a fluid flow path which is formed through the body 2 of the valve 1 between the inlet 4 and the outlet 6 in an open condition of the valve 1, wherein the spring 10 biases the piston member 8 in the first direction D to form the fluid flow path, in the open condition of the valve 1, for fluid to flow through the body 2 of the valve 1, and wherein at least a portion of the fluid flow path is provided around the spring chamber 73 and exterior of the spring chamber 73. 14v T-44 00-
    公开号:AU2013205203A1
    申请号:U2013205203
    申请日:2013-04-14
    公开日:2013-11-21
    发明作者:Marcus Eric Ullrot
    申请人:Australian Valve Group Pty Ltd；
    IPC主号:F16K17-04
    专利说明:
    1 P/00/011 28/5/91 Regulation 3.2 AUSTRALIA Patents Act 1990 ORIGINAL COMPLETE SPECIFICATION STANDARD PATENT Applicant: Australian Valve Group Pty Ltd Actual Inventor: Marcus Eric Ullrot Invention Title: Valve Address for service: Golja Haines & Friend PO Box 1417 West Leederville Western Australia 6901 The following statement is a full description of this invention, including the best method of performing it known to us: 2 Title "Valve" Field of the Invention The present invention relates to a valve. 5 Throughout this specification, unless the context requires otherwise, the word "comprise" and variations such as "comprises", "comprising" and "comprised" are to be understood to imply the presence of a stated integer or group of integers but not the exclusion of any other integer or group of integers. Throughout this specification, unless the context requires otherwise, the word 10 "include" and variations such as "includes", "including" and "included" are to be understood to imply the presence of a stated integer or group of integers but not the exclusion of any other integer or group of integers. The headings in this specification are provided for convenience to assist the reader, and they are not to be interpreted so as to narrow or limit the scope of the 15 disclosure in the description, claims, abstract or drawings. Background Art The discussion of the background art, any reference to a document and any reference to information that is known, which is contained in this specification, is provided only for the purpose of facilitating an understanding of the background 20 art to the present invention, and is not an acknowledgement or admission that any of that material forms part of the common general knowledge in Australia or any other country as at the priority date of the application in relation to which this specification was filed. Valves are known in the art that are able to control, i.e. limit, an inlet supply line 25 pressure to a set maximum and to remain in the open condition if the pressure in the supply line falls below the set maximum pressure. Such valves are sometimes referred to in the art as pressure limiting valves. They are typically used in 3 plumbing installations, e.g. in household appliances, such as dishwashers, washing machines, tap mixers and water filtering systems. They may also be used in plumbing installations to reduce water hammer. However, such prior art valves can be somewhat bulky in size relative to the 5 function they perform. The size translates to weight due to the corresponding amount of material needed to manufacture the valves. Their size and weight results in an increase in the manufacturing costs and the end cost to a purchaser. Disclosure of the Invention In accordance with one aspect of the present invention there is provided a valve 10 comprising a body, an inlet for fluid to enter the body, an outlet for fluid to exit the body, a piston member moveable within the body, and 15 a spring located in a spring chamber to bias the piston member in a first direction, and a fluid flow path which is formed through the body of the valve between the inlet and the outlet in an open condition of the valve, wherein the spring biases the piston member in the first direction in the open 20 condition of the valve for fluid to flow via the fluid flow path through the body of the valve, and wherein at least a portion of the fluid flow path is provided around the spring chamber and exterior of the spring chamber. Preferably, a piston housing is provided in the body and at least part of the piston member is retained in the piston housing. 25 Preferably, the spring chamber is provided in the piston housing. Preferably, the said portion of the fluid flow path is provided around the piston housing and exterior of the piston housing.
    4 Preferably, the valve further comprises a valve seat and the piston member is provided with a piston head that seats on the valve seat in a closed condition of the valve and unseats from the valve seat in an open condition of the valve. Preferably, the cross sectional area of the fluid flow path between the piston 5 housing and the piston head is substantially equal. Preferably, seals are provided to prevent entry of fluid into the spring chamber. The seals may be provided in the form of O-rings. Preferably, the spring biases the piston member in the first direction to unseat the piston head from the valve seat in the open condition of the valve. 10 Preferably, in the closed condition of the valve, the resulting force, from the fluid pressure, on the upstream side of the valve seat that acts on the piston member in the first direction is substantially zero. In some embodiments, preferably, the piston housing comprises a passage for flow of fluid therethrough and the passage forms part of the fluid flow path.. 15 The piston member may be provided with a cavity and the spring is at least partly located in the cavity. Preferably, the inlet, outlet and spring are substantially axially aligned. In one embodiment, preferably, the valve seat is connected with the piston housing. 20 In some embodiments, the piston head is provided with a seal that seals against the valve seat in the closed condition of the valve and the seal defines the largest diameter of the piston head. The seal is compressed mainly radially by the valve seat in the closed condition of the valve. Brief Description of the Drawings 25 The present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a perspective view of a first embodiment of a valve in accordance with the present invention; 5 Figure 2A is a longitudinal cross-sectional view of the valve, shown in Figure 1, in an open condition; Figure 2B is a longitudinal cross-sectional view of the valve, shown in Figure 1, in a closed condition; 5 Figure 3 is a perspective view of the inlet part of the valve shown in Figure 1; Figure 4 is a perspective view of the outlet part of the valve shown in Figure 1; Figure 5A is a side view of the mid part of the valve shown in Figure 1; Figure 5B is a first perspective view of the mid part shown in Figure 5A; Figure 5C is a second perspective view of the mid part shown in Figure 5A; 10 Figure 5D is a first end view of the mid part shown in Figure 5A; Figure 5E is a cross-sectional view taken along the line A - A in Figure 5D; Figure 5F is a second end view of the mid part shown in Figure 5A; Figure 5G is a cross-sectional view taken along the line B - B of Figure 5F; Figure 6A is a perspective view of the piston member, without the piston head 15 and O-rings, of the valve shown in Figure 1; Figure 6B is a side view of the piston member shown in Figure 6A; Figure 6C is a longitudinal cross-sectional view of the piston member shown in Figure 6A; Figure 7A is first perspective view of the seal nut of the piston head of the valve 20 shown in Figure 1; Figure 7B is second perspective view of the seal nut shown in Figure 7A; Figure 7C is a cross sectional view of the seal nut shown in Figure 7A; Figure 8A is a perspective view of the valve seat of the valve shown in Figure 1; Figure 8B is a cross-sectional view of the valve seat shown in Figure 8A; 6 Figure 9A is a longitudinal cross-sectional view of a second embodiment of a valve, in accordance with the present invention, in an open condition; Figure 9B is a longitudinal cross-sectional view of the valve, shown in Figure 9B, in a closed condition; 5 Figure 10A is a perspective view of the piston member, without the piston head and O-rings, of the valve shown in Figure 9A; Figure 1OB is a side view of the piston member shown in Figure 1 0A; Figure 10C is a longitudinal cross-sectional view of the piston member shown in Figure 10A; 10 Figure 1 1A is first perspective view of the seal nut of the piston head of the valve shown in Figure 9A; Figure 11 B is second perspective view of the seal nut of the piston head of the valve shown in Figure 9A; Figure 11C is a cross sectional view of the seal nut of the piston head of the valve 15 shown in Figure 9A; Figure 12A is a side view of the valve seat of the valve shown in Figure 9A; Figure 12B is a cross-sectional view of the valve seat shown in Figure 12A; Figure 13A is a second cross-sectional view of the valve, shown in Figure 2A, in an open condition, in which surfaces of the piston member have been labelled; 20 Figure 13B is a schematic illustration of the projected areas on the YZ plane of the pressure acting on the surfaces, of the piston member, as illustrated in Figure 13A; Figure 13C is a second cross-sectional view of the valve, shown in Figure 9A, in an open condition, in which surfaces of the piston member have been labelled; 25 Figure 13D is a schematic illustration of the projected areas on the YZ plane of the pressure acting on the surfaces, of the piston member, as illustrated in Figure 13C; 7 Figure 14A is a side view of a third embodiment of a valve in accordance with the present invention; Figure 14B is a longitudinal cross-sectional view of the valve, shown in Figure 14A, in an open condition; 5 Figure 14C is a longitudinal cross-sectional view of the valve, shown in Figure 14A, in a closed condition; Figure 15A is a first perspective view of the inlet part of the valve shown in Figure 14A; Figure 15B is a second perspective view of the inlet part of the valve shown in 10 Figure 14A; Figure 16A is a first perspective view of the outlet part of the valve shown in Figure 14A; Figure 16B is a second perspective view of the outlet part of the valve shown in Figure 14A; 15 Figure 17A is a side view of the piston housing of the valve shown in Figure 14A; Figure 17B is a first perspective view of the piston housing shown in Figure 17A; Figure 17C is a second perspective view of the piston housing shown in Figure 17A; Figure 17D is a first end view of the piston housing shown in Figure 17A; 20 Figure 17E is a second end view of the piston housing shown in Figure 17A; Figure 18A is a first perspective view of the piston member, without the piston head and O-rings, of the valve shown in Figure 17A; Figure 18B is a second perspective view of the piston member shown in Figure 18A; 25 Figure 18C is a side view of the piston member shown in Figure 18A; Figure 19A is a side view of the valve seat of the valve shown in Figure 14A; Figure 19B is a first perspective view of the valve seat shown in Figure 20A; 8 Figure 19C is a second perspective view of the valve seat shown in Figure 20A; and, Figure 20A is a longitudinal cross-sectional view of a fourth embodiment of a valve, in accordance with the present invention, in an open condition; 5 Figure 20B is a longitudinal cross-sectional view of the valve, shown in Figure 20A, in a closed condition; Figure 21A is a first perspective view of the piston housing and valve seat, without the 0-rings, of the valve shown in Figure 20A; Figure 21B is a second perspective view of the piston housing and valve seat 10 shown in Figure 21A; Figure 21C is a side view of the piston housing and valve seat shown in Figure 21A; Figure 21 D is a first end view of the piston housing and valve seat shown in Figure 21A; and, 15 Figure 21 E is a second end view of the piston housing and valve seat shown in Figure 21A; Best Mode(s) for Carrying Out the Invention First Embodiment In the drawings of the first embodiment (Figures 1 to 8B and Figures 13A and 20 13B), there is shown a valve 1 comprising a body 2, an inlet 4 for fluid to enter the body 2, an outlet 6 for fluid to exit the body 2, a piston member 8 moveable within the body 2 and a spring 10 to bias the piston member 8 in a first direction shown by the arrow D in Figures 2A and 2B. The piston member 8 may be provided with a cavity 12. 25 The spring 10 biases the piston member 8 in the direction D such that a fluid flow path is formed between the inlet 4 and the outlet 6 in an open condition of the valve 1.
    9 With particular reference to Figures 1 to 5G, the body 2 comprises a first, or inlet, body part 14, a second, or mid, body part 16 and a third, or outlet, body part 18. The inlet part 14 and outlet part 18 are connected adjacent respective ends of the mid part 16. The inlet part 14, the mid part 16 and the outlet part 18 are provided 5 with suitable connection means so that they can be connected, as will be further described herein. The inlet part 14 and the outlet part 18 are substantially in the form of unions. The inlet part 14 is provided with the inlet 4 and the outlet part 18 is provided with the outlet 6. A screw thread 20 is provided adjacent one end of the inlet part 14, at its inner 10 surface. A screw thread 22 is provided adjacent one end of the outlet part 18, at its inner surface. The outer surface of the mid part 16 is provided with a screw thread 24 and a screw thread 26 adjacent respective ends of the mid part 16. The screw thread 20 of the inlet part 14 engages with the screw thread 24 of the mid part 16 to thereby connect together the inlet part 14 and the mid part 16. An 0 15 ring 28 is provided between the inlet part 14 and mid part 16 adjacent the screw threaded connection between the screw threads 20 and 24 to form a fluid tight seal. This fluid tight seal prevents fluid leaking from inside the valve 1, through the screw threaded connection between the inlet part 14 and the mid part 16. Similarly, the screw thread 22 of the outlet part 18 engages with the screw thread 20 26 at the other end of the mid part 16 to thereby connect together the mid part 16 and the outlet part 18. An O-ring 30 is provided between the mid part 16 and the outlet part 18 to form a fluid tight seal. This fluid tight seal prevents fluid leaking from inside the valve 1, through the screw threaded connection between mid part 16 and the outlet part 18. However, since the inlet part 14, mid part 16 and outlet 25 part 18 are screw threadedly connected together, they may be disconnected, i.e. detached, from one another by unscrewing the screw threaded connections. The inlet part 14, mid part 16 and outlet part 18 may also be reconnected via the screw threads 20 and 24 and the screw threads 22 and 26. The inlet part 14, mid part 16 and outlet part 18 may be reconnected by engaging and retightening their 30 respective screw threads 20, 22, 24 and 26. A thread locking/sealing compound (for example, such as that sold under the trade mark LOCTITE*) may be applied to the screw threads 20, 22, 24 and 26 prior to engaging and re-tightening them. The other respective ends of the inlet part 14 and the outlet part 18 are each provided with suitable connection means to connect the inlet part 14 and the 10 outlet part 18 to tubing or pipes such as, for example, pipes in a plumbing installation. In that regard, the inlet part 14 may be provided with a screw thread 29 at its other end. Similarly, the outlet part 18 may be provided with a screw thread 31 at its other end. In use, the screw threads 29 and 31 are used to 5 connect the valve 1 to the pipes, such as pipes in a plumbing installation. Whilst both of the screw threads 29 and 31 are shown in Figures 1 to 4 as being on the exterior (i.e. male screw threads) of the inlet part 14 and the outlet part 18, in alternative embodiments (not shown) one or both of these screw threads may be provided on the interior (i.e. a female screw thread) of the inlet part 14 and the 10 outlet part 18. With particular reference to Figures 2A and 2B and Figures 6A to 6C, the piston member 8 comprises a piston head (or valve head) 32, a base 34 and a neck 36 extending between the piston head 32 and the base 34. The cavity 12 is provided in the base 34 of the piston member 8. The base 34 has an opening 38. The 15 spring 10 extends from the cavity 12 via the opening 38. (Figures 6A, 6B and 6C show the piston member 8, without the seal 40 and seal nut 42 of the piston head 32.) The piston head 32 has a seal 40 which is retained in position by a seal nut 42. The seal 40 may be an O-ring. The seal nut 42 engages with a screw thread 43 20 adjacent the end of the piston member 8 at which the piston head 32 is located. The seal 40 is substantially annular. The piston member 8 is provided with a shoulder 44. The shoulder 44 is formed at the region between the base 34 and the neck 36. The neck 36 has a curved surface 46. As best seen when the piston member 8 is viewed to see its longitudinal dimension, the curved surface 46 has a 25 gradually decreasing cross-sectional diameter from the respective ends of the neck 36 to the mid region of the neck 36, i.e. from the respective ends of the neck 36 adjacent the shoulder 44 and the piston head 32, toward the mid region of the neck 36. An annular surface 49 is provided at the piston head 32, adjacent the end of the neck 36 that is adjacent the piston head 32. 30 As best seen in Figures 6A and 6B, the base 34 of the piston member 8 is provided with circumferential grooves 48. The grooves 48 accommodate respective O-rings 50.
    11 The seal nut 42 is shown separately in Figures 7A to 7C. The seal nut 42 has an annular recess 42a and a screw thread 42b. The recess 42a receives the seal 40. The screw thread 42b engages with the screw thread 43 that is adjacent the end of the piston member 8 at which the piston head 32 is located. The seal 40 abuts 5 with the annular surface 49 and is sandwiched between the seal nut 42 and the annular surface 49. A valve seat 52 is provided in the body 2. The valve seat 52 can be seen in Figures 2A and 2B and is shown separately in Figures 8A and 8B. The valve seat 52 defines an upstream side and a downstream side. The upstream side of the 10 valve seat 52 is the side that faces the inlet 4 and the downstream side is the side that faces the outlet 6. The valve seat 52 is retained between the mid part 16 and the outlet part 18. The valve seat 52 is retained between an internal annular ledge 54 of the outlet part 18 and an annular end 56 of the mid part 16. The valve seat 52 is substantially annular in shape. The valve seat 52 has a seating surface 58 15 around an opening 60 through the valve seat 52. The valve seat 52 is provided with a groove 62 in its outer surface. An O-ring 64 is located in the groove 62. The O-ring 64 seals against the internal surface of the outlet part 18 to ensure that fluid cannot leak between the wall of the body 2 and the valve seat 52. The base 34 of the piston member 8 is retained by a piston housing 66. The 20 piston housing 66 is formed by a wall 68 of the mid part 16 of the body 2. The piston housing 66 is provided with an inwardly turned flange 70. The flange 70 surrounds an opening 72 of the piston housing 66 at one end thereof. A spring chamber 73 is formed by the interior of the piston housing 66. The O-rings 50 form a fluid tight seal against the internal surface of the wall 68 to prevent entry of 25 fluid into the spring chamber 73, in the interior of the piston housing 66, and the cavity 12 so as to prevent fluid coming into contact with the spring 10. The shoulder 44 of the piston member 8 is able to abut against the flange 70 to prevent further movement of the piston member 8 in the direction D as will be further described herein. Thus, the flange 70 acts as a stop to limit the travel of 30 the piston member 8 in the direction D. In an alternative embodiment (not shown), the spring chamber 73 may be vented to the exterior of the valve 1. This may be achieved by a vent passage extending from the spring chamber 73, through the wall 68 of the piston housing 66 (and the mid part 16) to an opening at the exterior of the valve 1.
    12 The cross-sectional diameter of the neck 36 of the piston member 8 is less than the diameter of the opening 60 of the valve seat 52 and the opening 72 of the piston housing 66. This allows the neck 36 to pass freely, in either direction (i.e. in the direction D or the direction opposed to the direction D), through the opening 5 60 and the opening 72 when the piston member 8 moves within the body 2. The piston housing 66 has another opening 74. The opening 74 is opposed to the opening 72 and is located adjacent to the inlet part 14. The opening 74 is closed off by a spring holder cap 76. The spring holder cap 76 has an external screw thread 78 which engages with an internal screw thread 80 in the wall 68 of the 10 piston housing 66 adjacent the opening 74. An O-ring 82 is provided around spring holder cap 76, and is located between the spring holder cap 76 and the mid part 16 to form a fluid tight seal to prevent entry of fluid into the spring chamber 73, in the interior of the piston housing 66, and the cavity 12 and thereby prevent fluid coming into contact with the spring 10. 15 The spring 10 is provided in the spring chamber 73. The spring 10 is retained in the spring chamber 73, in the piston housing 66, between the spring holder cap 76 and an abutment surface 83 of the base 34 inside the cavity 12. The spring 10 is partly located in the spring holder cap 76. The spring 10 is at least partly located in the cavity 12 of the piston member 8. 20 However, in an alternative embodiment (not shown), the cavity 12 may be omitted such that the spring 10 bears against the exterior of the base 34 of the piston member 8. In such an embodiment, a spring 10 of shorter the length is used. The mid part 16 is provided with a passage 84 extending from a first end 86 thereof, adjacent the inlet part 14, to a second end 88 adjacent the outlet part 18. 25 Fluid is able to flow through the passage 84 from the first end 86 to the second end 88 in an open condition of the valve 1. The passage 84 is substantially annular in cross-sectional shape, and is substantially in the form of an annular cylinder. The passage 84 is provided with a pair of arcuate (inlet) openings 90 at the first end 86 and an annular (outlet) opening 92 at the second end 88. The 30 arcuate openings 90 are separated by webs 94. The piston member 8 is moveable in the body 2 between a fully open condition and a closed condition as will be now described.
    13 The spring 10 biases the piston member 8 in the direction D to an open condition of the valve 1. An open condition of the valve 1 exists when the seal 40 of the piston head 32 is unseated from the seating surface 58 of the valve seat 52. In an open condition of the valve 1, a fluid flow path is formed through the body 2 of the 5 valve 1 between the inlet 4 and the outlet 6. The fluid flow path extends from the inlet 4 to the outlet 6, as will be further described herein. The fully open condition of the valve 1 occurs when the piston member 8 has moved within the body 2, in the direction D, such that it is unable to move any further in the direction D. The piston member 8 is unable to move any further in the direction D when the 10 shoulder 44 of the piston member 8 abuts against the flange 70 of the piston housing 66. Once the shoulder 44 abuts against the flange 70, further movement of the piston member 8 in the direction D is not possible. The maximum possible spacing between the piston head 32 and the seating surface 58 of the valve seat 52 occurs when the shoulder 44 abuts against the flange 70, i.e. when the valve 1 15 is in the fully open condition. The fully open condition of the valve 1 is shown in Figure 2A. The shapes of the valve seat 52 and the curved surface 46 of the neck 36 result in the fluid flow path at the region of the opening 60, in the valve seat 52, having a cross-sectional area that is substantially similar to the cross-sectional area of the 20 remainder of the fluid flow path from the openings 90 in the mid part 16 to the piston head 32 in the fully open condition of the valve 1. Thus, the cross sectional area of the fluid flow path between the piston housing 66 and the piston head 32 is substantially equal (or constant). This is best seen in Figure 2A. Thus, the fluid flow path through the valve 1 has a substantially constant cross-section from the 25 arcuate openings 90, through the passage 84 in the mid part 16 and to the piston head 32 in the fully open condition of the valve 1. This substantially constant cross-section results in a relatively smooth flow of fluid through the fluid flow path in the valve 1. In an open condition of the valve 1, a fluid flow path is formed through the body 2 30 of the valve 1 between the inlet 4 and the outlet 6. The fluid flow path extends from the inlet 4, through the inlet part 14, the passage 84 in the mid part 16, the opening 60 in the valve seat 52, around the piston head 32, and into the outlet part 18 and ends at the outlet 6.
    14 A portion of the fluid flow path is provided around the spring chamber 73 and is exterior of the spring chamber 73. This portion of the fluid flow path is also provided around the spring 10 and is exterior of the spring 10. This portion of the fluid flow path is also provided around the piston housing 66 and is exterior of the 5 piston housing 66. This portion of the fluid flow path is the portion formed substantially by the passage 84. The spring 10 and the portion of the fluid flow path that is provided around and exterior of the spring chamber 73 (and around and exterior of the spring 10) may be arranged such that they are substantially coaxial. 10 The arrangement of the valve 1, in which a portion of the fluid flow path is provided around the spring chamber 73 and exterior of the spring chamber 73, as herein before described, means that a spring 10 of relatively small diameter may be used. The spring 10 may be substantially helical. 15 The inlet 4, the outlet 6 and the spring 10 are substantially axially aligned. In the closed condition of the valve 1, the seal 40 of the piston head 32 seats on the seating surface 58 of the valve seat 52. The closed condition of the valve 1 is shown in Figure 2B. In the closed condition of the valve 1, the fluid cannot pass through the opening 60 of the valve seat 52. Accordingly, in the closed condition 20 of the valve 1, there is no fluid flow path that extends through the body 2 between the inlet 4 and the outlet 6 that allows flow of fluid from the inlet 4 to the outlet 6 since the opening 60 of the valve seat 52 is closed off by the seal 40 of the piston head 32. Second Embodiment 25 In Figures 9A to 12B and Figures 13C and 13D, there is shown a valve 200 in accordance with a second embodiment of the present invention. The valve 200 has many parts that are similar to those of the valve 1 of the first embodiment. The drawings of the first and second embodiments of the valves 1 and 200 use the same reference numerals to denote the same parts. Those parts 30 will not again be described with reference to the valve 200 of the second embodiment. It is to be understood that the description of such parts with 15 reference to the valve 1 of the first embodiment also applies to the valve 200 of the second embodiment. Accordingly, the description of the valve 200 will focus on the aspects of the valve 200 that are different from the valve 1. In that regard, the valve 200 has a piston member 208 with a piston head (or 5 valve head) 232 and neck 236 that are different from the corresponding parts (the piston head 32 and the neck 36) of the pressure reducing valve 1. In addition, the valve seat 252 of the valve 200 is different from the valve seat 52 of the pressure reducing valve 1. The piston head 232 has a seal 240 that is retained in position by a screw 242, 10 shown separately in Figures 11 A to 11C. The screw 242 has an annular recess 242a and a screw thread 242b. The recess 242a receives part of the seal 240. The screw thread 242b engages with an (internal) screw thread 243 (best seen in Figures 1 0A and 10C) at the end of the piston member 208 at which the piston head 232 is located. The screw 242 retains the seal 240 in place between a 15 shoulder 249, at the piston head 232, and the screw 242. The seal 240 is substantially annular, such as an O-ring. The piston head 232 is of a shape that substantially resembles an oblate spheroid, with the seal 240 provided at the circumference of its mid region, which in the case of an oblate spheroid, may be referred to as the equatorial 20 circumference. Thus, the seal 240 defines the largest diameter of the piston head 232. The neck 236 of the valve 200 has a curved surface 246. In other resects, the piston member 208 is substantially the same as the piston member 8 of the valve 1 of the first embodiment and the same reference 25 numerals have been used to denote the same parts. A valve seat 252 is provided in the body 2. The valve seat 252 can be seen in Figures 9A and 9B and is shown separately in Figures 12A and 12B. The valve seat 252 defines an upstream side and a downstream side. The upstream side of the valve seat 252 is the side that faces the inlet 4 and the downstream side is the 30 side that faces the outlet 6. The valve seat 252 is retained between the mid part 16 and the outlet part 18. The valve seat 252 is retained between an internal annular ledge 54 of the outlet part 18 and an annular end 56 of the mid part 16.
    16 The valve seat 252 is substantially annular in shape. The valve seat 252 has a seating surface 258 around an opening 260 through the valve seat 252. The seating surface 258 has a chamfered portion 258a, adjacent the downstream side of the valve seat 252, and an adjoining surface portion 258b at the inner mid 5 region of the valve seat 252. The valve seat 252 is provided with a groove 62 in its outer surface. An O-ring 64 is located in the groove 62. The O-ring 64 seals against the internal surface of the outlet part 18 of the body 2 to ensure that fluid cannot leak between the wall of the body 2 and the valve seat 252. The remaining parts and features of the valve 200 are the same as for the valve 1 10 of the first embodiment, as herein before described, including the operation of the valve 200 in the open and closed conditions, and will not be again described. However, it is to be understood that the description of those aspects of the valve 1 also applies to the valve 200. Third Embodiment 15 In Figures 14A to 19C, there is shown a valve 300 in accordance with a third embodiment of the present invention. The valve 300 has several parts that are similar to those of the valve 1 of the first embodiment or the valve 200 of the second embodiment. The drawings of the first, second, and third embodiments of the valves 1, 200 and 300 use the same 20 reference numerals to denote the same parts. Those parts will not again be described with reference to the valve 300 of the third embodiment. It is to be understood that the description of such parts with reference to the valve 1 of the first embodiment and the valve 200 of the second embodiment also applies to the valve 300 of the third embodiment. Accordingly, the description of the valve 300 25 will focus on the aspects of the valve 300 that are different from the valve 1 and the valve 200. The valve 300 comprises a body 302, an inlet 304 for fluid to enter the body 302, an outlet 306 for fluid to exit the body 302, a piston member 308 moveable within the body 302 and a spring 310 to bias the piston member 308 in a first direction 30 shown by the arrow D in Figures 14B and 14C. The piston member 308 may be provided with a cavity 12 17 The spring 310 biases the piston member 308 in the direction D such that a fluid flow path is formed between the inlet 304 and the outlet 306 in an open condition of the valve 300. With particular reference to Figures 14A to 16B, the body 302 comprises a first, or 5 inlet, body part 314, and a second, or outlet, body part 318. The inlet part 314 and outlet part 318 are connected adjacent respective ends. The inlet part 314 and the outlet part 318 are provided with suitable connection means so that they can be connected, as will be further described herein. The inlet part 314 and the outlet part 318 are substantially in the form of unions. The inlet part 314 is provided with 10 the inlet 304 and the outlet part 318 is provided with the outlet 306. A screw thread 320 is provided adjacent one end of the inlet part 314, at its outer surface, and a screw thread 322 is provided adjacent one end of the outlet part 318, adjacent its inner surface. The screw thread 320 may be provided at the outer surface of the inlet part 314 and the screw thread 322 may be provided at 15 the inner surface of the outlet part 318 (as shown in Figures 14A to 16B), or, alternatively, vice versa. The screw thread 320 of the inlet part 314 engages with the screw thread 322 of the outlet part 318 to thereby connect together the inlet part 314 and the outlet part 318. An O-ring 328 is provided between the inlet part 314 and outlet part 318 adjacent the screw threaded connection between the 20 screw threads 320 and 322 to form a fluid tight seal. This fluid tight seal prevents fluid leaking from inside the valve 300, through the screw threaded connection between the inlet part 314 and the outlet part 318. Since the inlet part 314 and the outlet part 318 are screw threadedly connected together, they may be disconnected, i.e. detached, from one another by unscrewing the screw threaded 25 connections, and they may be subsequently reconnected. This may be done in a similar manner to that described with reference to the inlet part 4, mid part 16 and outlet part 18 of the valve 1 of the first embodiment as herein before described. The other respective ends of the inlet part 314 and the outlet part 318 are each provided with suitable connection means to connect the inlet part 314 and the 30 outlet part 318 to tubing or pipes such as, for example, pipes in a plumbing installation. The inlet part 314 may be provided with a screw thread 29 at its other end and the outlet part 318 may be provided with a screw thread 31, as previously herein before described with reference to the inlet part 14 and the outlet part 18 of the valve 1 of the first embodiment.
    18 The piston member 308 is substantially the same as the piston member 208 of the valve 200 of the second embodiment and the same reference numerals have been used to denote the same parts. Accordingly, it is to be understood that the description of the piston member 208 also applies to the piston member 308 of 5 the valve 300. A valve seat 352 is provided in the body 302. The valve seat 352 can be seen in Figures 14B and 14C and is shown separately in Figures 19A to 19C. The valve seat 352 defines an upstream side and a downstream side. The upstream side of the valve seat 352 is the side that faces the inlet 304 and the downstream side is 10 the side that faces the outlet 306. The valve seat 352 is retained between the outlet part 318 and a piston housing 366, to be described. The valve seat 352 is retained between an internal annular ledge 354 of the outlet part 318 and the piston housing 366. The valve seat 352 is substantially annular in shape. The valve seat 352 has a seating surface 358 around an opening 360 through the 15 valve seat 352. The seating surface 358 has a chamfered portion 358a, adjacent the downstream side of the valve seat 352, and an adjoining portion 358b at the inner mid region of the valve seat 352. The valve seat 352 is provided with a groove 62 in its outer surface. An O-ring 64 is located in the groove 62. The 0 ring 64 seals against the internal surface of the outlet part 318 to ensure that fluid 20 cannot leak between the wall of the body 302 and the valve seat 352. The base 34 of the piston member 308 is retained by a piston housing 366. The piston housing 366 can be seen in Figures 14B and 14C and is shown separately in Figures 17A to 17E. The piston housing 366 comprises a substantially tubular, or sleeve-like, member 368 and a collar 369. The collar 369 is provided adjacent 25 one end of the tubular member 368. The piston housing 366 is provided with an inwardly turned flange 370 at one end of the tubular member 368. This is the end of the tubular member 368 adjacent which the collar 369 is provided. The flange 370 surrounds an opening 372 of the piston housing 366 at one end of the tubular member 368 thereof. A spring chamber 373 is formed by the interior of the piston 30 housing 366, inside the tubular member 368. The O-rings 50 form a fluid tight seal against the internal surface of the tubular member 368 to prevent entry of fluid into the spring chamber 373, in the interior of the piston housing 366, and the cavity 12 so as to prevent fluid coming into contact with the spring 310. The shoulder 44 of the piston member 308 is able to abut against the flange 370 to 19 prevent further movement of the piston member 308 in the direction D as will be further described herein. Thus, the flange 370 acts as a stop to limit the travel of the piston member 308 in the direction D. The cross-sectional diameter of the neck 36 of the piston member 308 is less 5 than the diameter of the opening 360 of the valve seat 352 and the opening 372 of the piston housing 366. This allows the neck 36 to pass freely, in either direction (i.e. in the direction D or the direction opposed to the direction D), through the opening 360 and the opening 372 when the piston member 308 moves within the body 302. 10 The piston housing 366 has another opening 374. The opening 374 is opposed to the opening 372 and is located in the inlet part 314. The opening 374 is closed off by a spring holder cap 376. The spring holder cap 376 has an external screw thread 378 that engages with an internal screw thread 380 in the tubular member 368 of the piston housing 366 adjacent the opening 374. An O-ring 382 is 15 provided around spring holder cap 376, and is located between the spring holder cap 376 and the tubular member 368 to form a fluid tight seal to prevent entry of fluid into the spring chamber 373, in the interior of the piston housing 366, and the cavity 12 and thereby prevent fluid coming into contact with the spring 310. The spring 310 is provided in the spring chamber 373. The spring 310 is retained 20 in the spring chamber 373, in the piston housing 366, between the spring holder cap 376 and an abutment surface 83 of the base 34 inside the cavity 12. The spring 310 abuts the spring holder cap 376 and may be partly located in the spring holder cap 376. The spring 310 is at least partly located in the cavity 12 of the piston member 308. 25 However, in an alternative embodiment (not shown), the cavity 12 may be omitted such that the spring 310 bears against the exterior of the base 34 of the piston member 308. In such an embodiment, a spring 310 of shorter the length is used. The tubular member 368 and the collar 369 are connected by webs 384. A passage 386 is formed between the tubular member 368 and the collar 369 for 30 fluid flow. This passage 386 is divided into separate passage sections 386a by the webs 384, in the radial direction, as can be seen in Figures 17C, 17D and 17E. The passage 386 is substantially annular in cross-section. The webs 384 20 may be substantially wedge-shaped and extend partly along the tubular member 368 away from the collar 369. The collar 369 of the piston housing 366 is held between an end of the inlet part 314 and the valve seat 352, in the valve 300, as can be seen in Figures 14A and 5 14B. A passage 388 is also formed between the outer surface 390 of the tubular member 368, of the piston housing 366, and the inner surface 391 of the inlet part 314 of the body 302. The passage 388 is substantially annular in cross-section, and is substantially in the form of an annular cylinder. 10 A passage 392 is also formed between the spring holder cap 376 and the inner surface 391 of the inlet part 314. The passage 392 is substantially annular in cross-section. Fluid is able to flow through the passages 392, 388, and 386 in an open condition of the valve 1, as will be further described herein. 15 The spring 310 biases the piston member 308 in the direction D to an open condition of the valve 300. An open condition of the valve 1 exists when the seal 240 of the piston head 232 is unseated from the seating surface 358 of the valve seat 352. In an open condition of the valve 300, a fluid flow path is formed through the body 302 of the valve 300 between the inlet 304 and the outlet 306. 20 The fluid flow path extends from the inlet 304 to the outlet 306, as will be further described herein. The fully open condition of the valve 300 occurs when the piston member 308 has moved within the body 302, in the direction D, such that it is unable to move any further in the direction D. The piston member 308 is unable to move any further in the direction D when the shoulder 44 of the piston member 25 308 abuts against the flange 370 of the piston housing 366. Once the shoulder 44 abuts against the flange 370, further movement of the piston member 308 in the direction D is not possible. The maximum possible spacing between the piston head 232 and the seating surface 358 of the valve seat 352 occurs when the shoulder 44 abuts against the flange 370, i.e. when the valve 300 is in the fully 30 open condition. The fully open condition of the valve 300 is shown in Figure 14B. The shapes of the valve seat 352 and the curved surface 46 of the neck 236 result in the fluid flow path at the region of the opening 360, in the valve seat 352, 21 having a cross-sectional area that is substantially similar to the cross-sectional area of the remainder of the fluid flow path from the spring holder cap 376 to the piston head 232 in the fully open condition of the valve 300. This is best seen in Figure 14B. Thus, the fluid flow path through the valve 300 has a substantially 5 constant cross-section from the spring holder cap 376, through the passage 392, the passage 388, the passage 386 and to the piston head 232 in the fully open condition of the valve 300. This substantially constant cross-section results in a relatively smooth flow of fluid through the fluid flow path in the valve 300. In an open condition of the valve 300, shown in Figure 2A, a fluid flow path is 10 formed through the body 302 of the valve 300 between the inlet 304 and the outlet 306. The fluid flow path extends from the inlet 304, then through the inlet part 314, the passage 392, the passage 388, the passage 386, the opening 360 in the valve seat 352, around the piston head 232, and into the outlet part 318 and ends at the outlet 306. 15 A portion of the fluid flow path is provided around the spring chamber 373 and is exterior of the spring chamber 373. This portion of the fluid flow path is also provided around the spring 310 and is exterior of the spring 310. This portion of the fluid flow path is also provided around the piston housing 366 and is exterior of the piston housing 366. This portion of the fluid flow path is the portion formed 20 substantially by the passages 388 and 386. The spring 310 and the portion of the fluid flow path that is provided around and exterior of the spring chamber 373 (and around and exterior of the spring 310) may be arranged such that they are substantially coaxial. The arrangement of the valve 300, in which a portion of the fluid flow path is 25 provided around the spring chamber 373 and exterior of the spring chamber 373, as herein before described, means that a spring 310 of relatively small diameter may be used. The spring 310 may be substantially helical. In the closed condition of the valve 300, the seal 240 of the piston head 232 seats 30 on the seating surface 358 of the valve seat 352. The closed condition of the valve 300 is shown in Figure 14C. In the closed condition of the valve 300, the fluid cannot pass through the opening 360 of the valve seat 352. Accordingly, in 22 the closed condition of the valve 300, there is no fluid flow path that extends through the body 302 between the inlet 304 and the outlet 306 that allows flow of fluid from the inlet 304 to the outlet 306 since the opening 360 of the valve seat 352 is closed off by the seal 240 of the piston head 232. 5 Fourth Embodiment In Figures 20A to 21 E, there is shown a valve 400 in accordance with a fourth embodiment of the present invention. The valve 400 has many parts that are similar to those of the valve 200 of the second embodiment and/or the valve 300 of the third embodiment. The drawings 10 of the second, third and fourth embodiments of the valves 200, 300 and 400, respectively, use the same reference numerals to denote the same parts. Those parts will not again be described with reference to the valve 400 of the fourth embodiment. It is to be understood that the description of such parts with reference to the valve 300 of the third embodiment also applies to the valve 400 15 of the fourth embodiment. Accordingly, the description of the valve 400 will focus on the aspects of the valve 400 that are different from the valve 300. In that regard, the valve 400 has a body 402, which comprises an inlet body part 414 and an outlet body part 418, along with an inlet 404, for fluid to enter the body 402, and an outlet 406, for fluid to exit the body 402. The inlet part 414 and the 20 outlet part 418 are connected adjacent respective ends. The valve 400 is provided with a housing unit 420. The housing unit 420 incorporates a piston housing 422 and a valve seat 424 into a single unit, whereas in the valve 300 of the third embodiment, the piston housing 366 and the valve seat 352 are separate components. The piston housing 422 is substantially 25 tubular, or sleeve-like. The housing unit 420 can be seen in Figures 20a and 20B and is shown separately in Figures 21A to 21E. Incorporating the piston housing 422 and the valve seat 424 as a single housing unit 420 means that the piston member 308, the piston housing 422 and the valve seat 424 may be inserted into and removed from the body 402 as a unit, i.e. the 30 piston member 308, the piston housing 422 and the valve seat 424 form a cartridge. Insertion may be performed by inserting them (as a single cartridge 23 unit) into the outlet part 418 and then connecting the inlet part 414 to the outlet part 418. Removal may be performed in the reverse way. The piston housing 422 and the valve seat 424 are spaced apart and are connected by webs 426 that extend therebetween. The webs 426 may extend 5 partly along the exterior surface of the piston housing 422, away from the valve seat 424. The webs 426 are provided with respective shoulders 430. Respective spaces 428 are defined by the piston housing 422, the valve seat 424 and the webs 426. The valve seat 424 defines an upstream side and a downstream side. The 10 upstream side of the valve seat 424 is the side that faces the inlet 404 and the downstream side is the side that faces the outlet 406. The housing unit 420 is retained in the body 402 of the valve 400 such that the valve seat 424 abuts the internal annular ledge 354 of the outlet part 418 and the shoulders 430 abut the end 432 of the inlet part 414 that is provided adjacent the 15 screw thread 320. The valve seat 424 is substantially annular in shape. The valve seat 242 has a seating surface 434 around an opening 436 through the valve seat 434. The seating surface 434 has a chamfered portion 434a, adjacent the downstream side of the valve seat 424, and an adjoining portion 434b at the inner mid region of the 20 valve seat 424. The valve seat 424 is provided with a groove 438 in its outer surface. An O-ring 64 is located in the groove 438. The O-ring 64 seals against the internal surface of the outlet part 418 to ensure that fluid cannot leak between the wall of the body 402 and the valve seat 424. The base 34 of the piston member 308 is retained in the piston housing 422. The 25 piston housing 422 is provided with an inwardly turned flange 370 at one end. This is the end of the piston housing 422 that is nearest the valve set 424. The flange 370 surrounds an opening 372 of the piston housing 422. A spring chamber 373 is formed by the interior of the piston housing 422. The O-rings 50 form a fluid tight seal against the internal surface of the piston housing 422 to 30 prevent entry of fluid into the spring chamber 373, in the interior of the piston housing 422, and the cavity 12 so as to prevent fluid coming into contact with the spring 310. The shoulder 44 of the piston member 308 is able to abut against the 24 flange 370 to prevent further movement of the piston member 308 in the direction D. Thus, the flange 370 acts as a stop to limit the travel of the piston member 308 in the direction D. The cross-sectional diameter of the neck 236 of the piston member 308 is less 5 than the diameter of the opening 436 of the valve seat 424 and the opening 372 of the piston housing 422. This allows the neck 236 to pass freely, in either direction (i.e. in the direction D or the direction opposed to the direction D), through the opening 436 and the opening 372 when the piston member 308 moves within the body 402. 10 A passage 444 is formed between the outer surface 390 of the piston housing 422 and the inner surface 391 of the inlet part 414 of the body 402. The passage 444 is substantially annular in cross-section, and is substantially in the form of an annular cylinder. Fluid is able to flow through the passages 392 and 444 and through the spaces 15 428 in an open condition of the valve 400, as will be further described herein. In an open condition of the valve 400 (i.e. when the seal 240 of the piston head 232 is unseated from the seating surface 434 of the valve seat 424), shown in Figure 20A, a fluid flow path is formed through the body 402 of the valve 400 between the inlet 404 and the outlet 406. The fluid flow path extends from the 20 inlet 404, then through the inlet part 414, the passage 392, the passage 444, then through the spaces 428, the opening 436 in the valve seat 424, around the piston head 232, and into the outlet part 418 and ends at the outlet 406. A portion of the fluid flow path is provided around the spring chamber 373 and is exterior of the spring chamber 373. This portion of the fluid flow path is also 25 provided around the spring 310 and is exterior of the spring 310. This portion of the fluid flow path is also provided around the piston housing 422 and is exterior of the piston housing 422. This portion of the fluid flow path is the portion formed substantially by the passage 444. The remaining parts and features of the valve 400 are the same as for the valve 30 300 of the third embodiment, as herein before described, including the operation of the valve 400 in the open and closed conditions, and will not be again 25 described. However, it is to be understood that the description of those aspects of the valve 300 also applies to the valve 400. Use and Operation of the Embodiments The manner of use and operation of the valve 1 of the first embodiment of the 5 present invention will now be described. In use, the valve 1 may be installed in a fluid supply line such as, for example, the supply line to a hot water heater, to limit the inlet supply line pressure to the set maximum pressure of the valve 1. The valve 1 is connected into the fluid supply line by way of the screw thread 29 of the inlet part 14 and the screw thread 31 of 10 the outlet part 18. Fluid that flows in the fluid supply line enters the valve 1 via the inlet 4 and exits via the outlet 6. The pressure of fluid, at the outlet 6, which has passed through the valve 1, cannot exceed the set maximum pressure of the valve 1. In addition, the valve 1 will remain in an open condition if the pressure of the fluid in the supply line, connected to the inlet part 14 of the valve 1, falls below 15 the set maximum pressure. A spring 10 of suitable spring force may be selected to achieve the maximum pressure of the valve 1. The set maximum pressure of a valve 1 indicates the maximum pressure, as measured at the outlet 6, at which fluid is able to pass through the valve 1. 20 In use, once flow of fluid commences through the fluid supply line (in which the valve 1 is connected), fluid flows into the valve 1 via the inlet 4. Flow of fluid through the fluid supply line may be commenced, for example, by opening a fluid outlet device (such as a tap) downstream of the valve 1. A fluid flow path is formed that extends between the inlet 4 and the outlet 6 through the body 2 of the 25 valve 1, as will be now described. The fluid enters the body 2 of the valve 1 via the inlet 4 and passes into the inlet part 14, then passes through the arcuate openings 90 and into the passage 84 in the mid part 16 and exits the passage 84 via the annular opening 92. The biasing action of the spring 10 on the piston member 8, in the direction D, and the pressure of the fluid flowing into the valve 1, 30 in the direction D, maintain the piston head 32 in a condition in which the seal 40 is unseated from the seating surface 58 of the valve seat 52, i.e. the valve 1 is maintained in an open condition, with the piston head 32 on the downstream side 26 of the valve seat 52. Consequently, the fluid is able to flow from the mid part 16, on the upstream side of the valve seat 52, through the opening 60 in the valve seat 52 and around the piston head 32 into the outlet part 18 on the downstream side of the valve seat 52. The fluid exits the body 2 of the valve 1 via the outlet 6. 5 In this way, a fluid flow path is formed which extends between the inlet 4 and the outlet 6 in an open condition of the valve 1. In the event that the pressure of the fluid entering the valve 1, via the inlet 4 at the inlet part 14, falls below the set maximum pressure of the valve 1, the spring 10 still continues to bias the piston member 8 in the direction D such that the piston 10 head 32 remains unseated from the seating surface 58 of the valve seat 52. Accordingly, the valve 1 remains in an open condition even if the pressure of the fluid entering the valve 1 falls below the set maximum pressure of the valve 1. Figures 13A and 13B schematically illustrate the fluid pressure acting on the piston member 8 in the open condition of the valve 1. The legend for the labelling 15 used in Figure 13A is set out below:
    A
    1 = Surface 1's (Si) projected area on the YZ-Plane
    A
    2 = Surface 2's (S 2 ) projected area on the YZ-Plane
    A
    3 = Surface 3's (S 3 ) projected area on the YZ-Plane Ares = The resulting projected area on the YZ-Plane after combining the 20 respective projected areas (with - or + to indicate the direction of the forces produced by the fluid pressure acting on the different surfaces of the piston member 8) P, = Pressure on the upstream side of the valve seat 44 (i.e. the upstream fluid pressure) 25 P 2 = Pressure on the downstream side of the valve seat 44 (i.e. the downstream fluid pressure) The equilibrium equation for the open condition of the valve (flow rate = 0) can be expressed as follows: k - Al - P 1
    -A
    1 + P 1
    -A
    2 - P 2 - A 3 = 0 ,(flow rate = 0 -> P, = P 2 ) 30 P 1 - (A, - A 2 + A 3 ) = k -Al
    P
    1 - (Ares) = k - Al 27 where: k = Spring rate of the spring 10 Al = Spring deflection of the spring 10 and the other parameters are as defined above. 5 In the closed condition of the valve 1, the area of A2 that the upstream fluid pressure acts on is only substantially 0% to 15% greater than the area of Al that the upstream fluid pressure acts on. This relatively small differential is beneficial because it is then predominantly the downstream fluid pressure that would be 10 responsible for the valve 1 to open again, in the sense that a drop in the downstream fluid pressure would be required. This makes the valve 1 less dependent on the magnitude of the pressure on the upstream side. Flow of fluid through the fluid supply line (in which the valve 1 is connected) may be stopped, for example, by closing the fluid outlet device. When this occurs, the 15 back pressure of the fluid in the fluid supply line on the downstream side of the valve 1 (i.e. downstream of the outlet 6) acts in the direction opposed to the direction D (i.e. in the upstream direction) against the biasing action of the spring 10. (The back pressure of the fluid in the fluid supply line on the downstream side of the valve seat 52 is also referred to herein as the downstream fluid pressure.) 20 This back pressure acts on the piston head 32 to move the piston member 8 in the direction opposed to the direction D until the piston head 32 seats on the valve seat 52 with the seal 40 of the piston head 32 seating, in sealing contact, on the seating surface 58 of the valve seat 52 to close the valve 1. The seating surface 58 is provided at the downstream side of the valve seat 52. The seal 40 is 25 compressed by the seating surface 58 in the direction D as well as radially towards and outwardly of its centre line. Accommodating part of the spring 10 within the cavity 12, provided in the piston member 8, contributes to the valve 1 having a compact structure. The manner of use and operation of the valve 200 of the second embodiment is 30 substantially similar to that of the valve 1 of the first embodiment of the present invention will now be described. The only difference occurs in the operation of the 28 piston head 232 of the valve 200 in the closed condition of the valve 200. This arises due to the different shape of the piston head 232. In that regard, in the closed condition of the valve 200 (shown in Figure 9B), the piston head 232 seats on the valve seat 252 such that the that the seal 240 is in 5 sealing contact with the seating surface 258 of the valve seat 252. In the closed condition of the pressure reducing valve 200, the seal 240 normally wedges against and seats on the chamfered portion 258a of the seating surface 258 at the region adjacent the adjoining surface portion 258b. However, it may seat on the adjoining surface portion 258b under some conditions such as, for example, in 10 the event of a shock pressure rise on the downstream side of the valve seat 252. In the closed condition of the pressure reducing valve 200, the fluid cannot pass through the opening 260 of the valve seat 252. Accordingly, in the closed condition of the pressure reducing valve 200, there is no flow path that extends between the inlet 4 and the outlet 6 since the opening 260 of the valve seat 252 is 15 closed off by the piston head 232. Figures 13C and 13D schematically illustrate the fluid pressure acting on the piston member 208 in the open condition of the valve 200. The description of Figures 13A and 13B, in relation to the valve 1 of the first embodiment, also applies to Figures 13C and 13D. Figures 13C and 13D and the description of 20 those Figures are also applicable to the valves 300 and 400 of the third and fourth embodiments. In other resects, the manner of use and operation of the valve 200 is substantially the same as the manner of use and operation of the valve 1 of the first embodiment as herein before described. 25 The manner of use and operation of the valve 300 of the third embodiment of the present invention will now be described. The manner of use and operation of the valve 300 is substantially the same as the manner of use and operation of the valve 1 of the first embodiment and the valve 200 of the second embodiment as herein before described. The only difference is that, in the valve 300, the portion 30 of the fluid flow path (in the open condition of the valve 300) that is between the inlet part 314 and the valve seat 352, is formed by the passages 392, 388 and 386. Thus, in the open condition of the valve 300, the fluid is able to flow through the fluid flow path, which extends from the inlet 304, into the inlet part 314, 29 followed by the passages 392, 388 and 386, through the opening 360 in the valve seat 352 and into the outlet part 318 and ends at the outlet 306. The fluid flows out of the valve 300 via the outlet 306. In other resects, the manner of use and operation of the valve 300 is substantially 5 the same as the manner of use and operation of the valve 1 of the first embodiment and the valve 200 of the second embodiment as herein before described. The manner of use and operation of the valve 400 is substantially the same as the manner of use and operation of the valve 300 of the third embodiment. The 10 only difference is that, in the valve 400, the portion of the fluid flow path (in the open condition of the valve 400) that is between the passage 392 and the valve seat 424, is formed by the passage 444 and the spaces 428. Thus, in the open condition of the valve 400, the fluid is able to flow through the fluid flow path, which extends from the inlet 404, into the inlet part 414, followed by the passages 15 392 and 444, through the spaces 428 and then the opening 436, in the valve seat 424, and into the outlet part 418 and ends at the outlet 406. The fluid flows out of the valve 400 via the outlet 406. In other resects, the manner of use and operation of the valve 400 is substantially the same as the manner of use and operation of the valve 300 of the third 20 embodiment as herein before described. Whilst preferred embodiments of the present invention have been herein before described, the scope of the present invention is not limited to those specific embodiments, and may be embodied in other ways, as will be apparent to a skilled addressee. 25 Modifications and variations such as would be apparent to a skilled addressee are deemed to be within the scope of the present invention.
    权利要求:
    Claims (16)
    [1] 1. A valve comprising a body, an inlet for fluid to enter the body, 5 an outlet for fluid to exit the body, a piston member moveable within the body, and a spring located in a spring chamber to bias the piston member in a first direction, and a fluid flow path which is formed through the body of the valve between the 10 inlet and the outlet in an open condition of the valve, wherein the spring biases the piston member in the first direction in the open condition of the valve, for fluid to flow via the fluid flow path through the body of the valve, and wherein at least a portion of the fluid flow path is provided around the spring chamber and exterior of the spring chamber. 15
    [2] 2. A valve according to claim 1, further comprising a piston housing provided in the body and at least part of the piston member is retained in the piston housing.
    [3] 3. A valve according to claim 2, wherein the spring chamber is provided in the piston housing. 20
    [4] 4. A valve according to claim 2 or 3, wherein said portion of the fluid flow path is provided around the piston housing and exterior of the piston housing.
    [5] 5. A valve according to any one of the preceding claims, further comprising a valve seat and the piston member is provided with a piston head that seats on the valve seat in a closed condition of the valve and unseats from the valve 25 seat in an open condition of the valve.
    [6] 6. A valve according to any one of the preceding claims, wherein the cross sectional area of the fluid flow path between the piston housing and the piston head is substantially equal. 31
    [7] 7. A valve according to any one of the preceding claims, wherein seals are provided to prevent entry of fluid into the spring chamber.
    [8] 8. A valve according to any one of the preceding claims wherein, the spring biases the piston member in the first direction to unseat the piston head from 5 the valve seat in an open condition of the valve.
    [9] 9. A valve according to any one of the preceding claims wherein, in a closed condition of the valve, the area of A2, as herein before described and illustrated in Figures 13A, 13B, 13C and 13D of the accompanying drawings, that the upstream fluid pressure acts on is only substantially 0% to 15% 10 greater than the area of Al, as herein before described and illustrated in Figures 13A, 13B, 13C and 13D of the accompanying drawings, that the upstream fluid pressure acts on.
    [10] 10. A valve according to any one of the preceding claims, wherein the piston housing comprises a passage for flow of fluid therethrough and the passage 15 forms part of the fluid flow path.
    [11] 11. A valve according to any one of the preceding claims, wherein the piston member is provided with a cavity and the spring is at least partly located in the cavity.
    [12] 12. A valve according to any one of the preceding claims, wherein the inlet, the 20 outlet and the spring are substantially axially aligned.
    [13] 13. A valve according to any one of the preceding claims, wherein the valve seat is connected with the piston housing.
    [14] 14. A valve according to any one of the preceding claims, wherein the piston head is provided with a seal that seals against the valve seat in the closed condition 25 of the valve and the seal defines the largest diameter of the piston head.
    [15] 15. A valve according to claim 14, wherein the seal is compressed mainly radially by the valve seat in the closed condition of the valve.
    [16] 16. A valve substantially as herein before described with reference to: Figures 1 to 8B, Figure 13A and Figure 13B; Figures 9A to 12B, Figure 13C and Figure 32 13D; Figures 14A to 19C, Figure 13C and Figure 13D; or Figures 20A to 21E, Figure 13C and Figure 13D.
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    同族专利:
    公开号 | 公开日
    AU2013205203B2|2017-02-02|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    US9476599B2|2013-08-04|2016-10-25|Triteck Limited|Hot water storage unit, relief device and method of making a hot water storage unit|US3794077A|1972-12-15|1974-02-26|C Fanshier|Excess flow check valve|
    US5215113A|1991-06-20|1993-06-01|Terry Paul E|Precision safety shut-off valve|
    US7219690B2|2004-03-11|2007-05-22|Watkins Manufacturing Corporation|Flow control valve|
    US20080295899A1|2007-05-30|2008-12-04|Smart Parts, Inc.|Compressed gas regulator|
    WO2010129640A2|2009-05-08|2010-11-11|Daas Ip Management, Llc|Safety relief fill valve assembly|
    法律状态:
    2017-06-01| FGA| Letters patent sealed or granted (standard patent)|
    优先权:
    申请号 | 申请日 | 专利标题
    AU2012901796||2012-05-02||
    AU2012901796A|AU2012901796A0||2012-05-02|Valve|
    AU2013205203A|AU2013205203B2|2012-05-02|2013-04-14|Valve|AU2013205203A| AU2013205203B2|2012-05-02|2013-04-14|Valve|
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