Valves for fluids

Abstract: A bellows valve comprises a main body (16) defining a valve chamber (18) including a valve seat (28) and having inlet and outlet passages (20, 22) connected therewith. A valve element (24) is positioned in the chamber (18) and has an operating stem (30) with a free end extending axially therefrom. An actuating assembly (14) for moving the valve element (24) towards and away from the seat (28), includes a rotatably mounted actuating shaft (58) having a free end axially aligned with the free end of the operating stem (30) and a handle (60) for producing axial movement of the actuating shaft (58). The operating stem (30) is joined to the actuating shaft (58) by a connection including a first ball (80) positioned axially between the free ends of the operating stem (30) and the actuating shaft (58) with a spring (86) engaged with the first ball (80) and acting to bias the free ends of the operating stem (30) and actuating shaft (58) axially apart. A plurality of second balls (94) interconnect the stem (30) and shaft (58) for preventing axial separation of the free ends while permitting free relative rotation therebetween.

Description: The invention relates to valves having improved operators. The invention is particularly suited for use in bellows type valves and will be described with particular reference thereto; however, the invention is capable of broader application and could be incorporated in many different types of valves. Corrugated bellows members formed from metal provide a highly efficient method of sealing valve chambers. Bellows-sealed valves are well known and widely used when hermetically sealing and/or the elimination of mechanical seals is desired. Typically, the metal bellows members used for valve sealing have a long life. Generally they are capable of undergoing a very large number of operating cycles so long as they are subjected to only axial extension and contraction and are not also subjected to torque. When bellows-sealed valves are actuated through the use of air cylinders or similar linear motion devices, torque problems are not present. However, when using rotary actuators, such as a rotary threaded operating stem, torque transmission to the bellows becomes a problem. Similarly, problems can be encountered with other actuators such as certain toggle and lever actuators. Many different solutions have been proposed for eliminating the various problems discussed above. For example, a variety of pinned, non-torque transmissive joints have been used. These are illustrated, for example in US-A- 1,906,313, US-A- 3,278,156 and US-A- 3,491,789. Generally, however, these prior arrangements transmit some torque and typically have an undesirable amount of backlash. An object of the invention is to overcome the problems discussed above and to provide a valve and actuating assembly which substantially eliminates torque transmission between a rotary actuator and the valve element while also eliminating backlash. GB-A-683,387 discloses a valve of the kind comprising a valve body defining a valve chamber having inlet and outlet flow passages interconnected through a valve seat; a valve element carried on an operating stem in said valve chamber for movement towards and away from said seat; and means for moving the operating stem, the last-mentioned means comprising an actuating shaft carried by said body and having a free end axially aligned with a free end of said operating stem; and connecting means joining said actuating shaft to said operating stem for permitting transfer of axial forces therebetween while preventing transfer of torque, said connecting means including a ball positioned between and axially aligned with said free ends of said actuating shaft and said operating stem; and retaining means for preventing axial separation of said operating stem and said actuating shaft while allowing free relative rotation therebetween. A valve of the above kind is characterised in that a spring means acts against said ball to apply a biasing force acting to bias said operating stem and said actuating shaft in axially opposite directions. The retaining means may comprise at least one ball, preferably a plurality of second balls located between the operating stem and the actuating shaft at locations radially outwards of the first mentioned ball. It is preferable for the second balls to be carried in openings formed about the actuating shaft or the operating stem and for them to engage in a circumferentially extending groove formed in the operating stem or the actuating shaft. It is further desirable for the second balls to be equally spaced circumferentially of the axis of the first ball at a location radially spaced therefrom. The combination of the first ball and its associated compression spring acts to permit axial force to be transmitted between the actuating shaft and the operating stem. The retaining means, such as the second balls and their interconnection between the operating stem and the actuating shaft, allows tensile forces to be carried by the connection between the operating stem and the actuating shaft. The overall combination of the elements does, however, substantially eliminate the transmission of torque between the rotatable actuating shaft and the axially driven operating stem. The means for moving the actuating shaft can be of a variety of types. For example, the actuating shaft can be a simple rotary actuator with external threads for producing the desired axial movement. Alternatively, various types of toggle and lever arrangements can be used to produce axial movement with a lesser component of rotary movement. Accordingly, one object of the invention is the provision of a valve actuating system which is particularly useful in bellows type valves for eliminating backlash and torque transmission between a rotary actuating shaft and a linearly movable operating stem. A further object is the provision of a connecting and force transmission system for use in valve operators wherein all of the axial forces are transmitted through rotary mounted balls which are maintained under a bias to eliminate backlash. A still further object is the provision of a system of the type described which is relatively simple and highly reliable. The invention is further described, by way of example, with reference to the accompanying drawings, wherein:- Fig. 1 is a vertical cross-sectional view through a bellows type valve incorporating a manually actuated rotary operator; Fig. 2 is a view similar to Fig. 1 but illustrating a toggle type operator; and Fig. 3 is a cross-section taken on line 3-3 of Fig. 1. Fig. 1 illustrates a bellows type valve 10 incorporating a body and valve housing assembly 12 carrying a rotary type manual actuator assembly 14. The valve body and housing assembly 12 could have a variety of constructions and arrangements but, in the illustrated embodiment, is the same as shown in US-A-4,687,017. As described in this prior patent, the body and housing assembly 12 comprises a main body 16 having a substantially cylindrical valve chamber 18 and inlet and outlet passages 20, 22. Mounted axially within the valve chamber 18 is a valve element 24 having a substantially cylindrical shape and carrying a replaceable valve tip member 26 arranged to cooperate with a seat 28. Movement of the valve element 24 is accomplished through a stem 30 which extends axially from the valve chamber 18. Movement of the stem 30 is guided by a sleeve bearing 32 carried in a gland member 34. In the illustrated embodiment, sealing of the valve chamber 18 is accomplished by a metal bellows member 36 which has its lower end joined at 38 to the inner end of the valve element 24. Preferably the joining is accomplished through a weld. The upper end of the bellows is likewise welded or otherwise positively joined at 40 to the inner end of the sealing gland 34. A seal between the gland 34 and the upper end of body 16 is provided by a bead 42 which engages a suitable sealing surface formed circumferentially about the upper end of the valve chamber 18. The gland member 34 is clamped into sealing position and held in proper alignment with the valve chamber by a bonnet member 44 and a bonnet nut 46. As illustrated, cooperating flanges 48, 50 are formed on the bonnet 44 and the bonnet nut 46 respectively. Threads 52 are formed internally of the nut 46 and are engaged with external threads 54 formed about the upper end of the body 16. In the embodiment under consideration, axial movement of the valve member 24 to move the valve tip 26 into and out of engagement with the seat 28 is accomplished through the manual actuator 14 which comprises an actuating shaft 58 terminating in an outer free end to which is connected an operating handle 60. The operating handle 60 is releasably connected through the use of a set screw 62 which engages with a flat 64 formed on the upper end of the actuating shaft 58. Rotary movement of the handle 60 is converted to axial movement through cooperating threads 66 and 68 formed about the enlarged lower exterior of the shaft 58 and the interior of the bonnet 44 respectively. A seal and guide ring 70 is carried in the upper end of the bonnet and retained therein by an inwardly extending flange 72. The guide and seal ring 70 serves to contain a lubricant sealed within the bonnet to maintain the cooperating threads 66, 68 properly lubricated. As previously discussed, metal bellows, such as the bellows member 36, are capable of undergoing axial flexure for an extremely high number of cycles without failure so long as they are not subjected to twisting to torsional forces. As a consequence, to utilize such bellows properly in a valve of the type under consideration, means must be provided to allow the axial movement of the actuating shaft 58 to be transferred to the operating stem 30 without conducting torque thereto. In particular, the connection used in the illustrated valve comprises a first rigid ball 80 which is carried within an inwardly extending and axially aligned cylindrical opening 82 formed in the enlarged lower end of the actuating shaft 58. The ball 80 is arranged to engage against a conical surface 84 formed at the inner end of the opening 82. To overcome backlash and, for reasons subsequently to be discussed, a relatively heavy coil spring 86 is carried within a small diameter bore 88 formed in the shaft 58 inwardly of ball 80. The spring 86 maintains a continual axial bias against the ball 80 acting to move it in a direction towards the upper end 90 of the operating stem 30. As illustrated, the upper end 90 of the operating stem 30 is sized so as to be closely received within the inwardly extending cylindrical bore 82. The end of stem 30 has a somewhat conical depression 92 which is engaged by the ball 80. The action of spring 86 maintains the ball in contact with the conical depression 92 and allows axial forces to be transmitted between the actuating shaft 58 and the operating stem 30. A positive axial connection between the operating stem 30 and the actuating shaft 58 is maintained by a set of second balls 94 which are positioned axially outwardly of the axis of ball 80 as illustrated in Fig. 3. In particular, there are preferably three of the balls 94 positioned at locations equally spaced circumferentially of operating stem 30. As shown, the balls 94 engage in a continuous peripheral groove 96 formed circumferentially about the upper end of stem 30. They are maintained in the groove 96 by being received through openings 98 formed through the wall of the inner end of actuating shaft 58. A circumferentially extending sleeve 100 is closely received on the end of actuating shaft 58 and is retained in position by a circumferentially extending snap ring or the like 102. The arrangement of the balls 94 assures that there is a direct and positive connection between actuating shaft 58 and operating stem 30 for conducting forces and producing simultaneous axial movement between the actuating shaft 58 and the operating stem 30. However, the arrangement is clearly such that free relative rotational movment can take place between the two components and no torque or rotary movement will be conducted therebetween. In addition, the arrangement of the compression spring 86 assures that backlash or lost motion will be maintained at a minimum during reversing movement of the actuating shaft 58. Fig. 2 illustrates the invention as applied to a toggle type valve actuator. In the embodiment of Fig. 2, like reference numerals differentiated by a prime suffix have been used to illustrate the same or corresponding parts as those previously discussed with reference to Fig. 1 embodiment. New or modified elements are identified with new numerals. In the Fig. 2 embodiment, the actuating shaft 58′ has a reduced diameter upper end portion 110 which extends through a suitable guide element 112 carried in the upper end of bonnet 44′. In this embodiment, the actuating shaft 58′ is maintained under a continuous downward bias by a relatively heavy compression spring 114 received about the exterior of the actuating shaft 58′. The lower end of spring 114 engages against a shoulder 116 formed on actuating shaft 58′. The upper end of the spring 114 engages as shown against the inwardly extending flange 72 on the upper end of bonnet 44′. This continually biases the valve element 24′ and the valve tip 26′ towards a closed position relative to the valve seat 28′. In this embodiment, the means for moving the valve stem 30′ in a direction to move the valve 24′ away from the seat 28′ comprises a toggle handle 118 which is connected to the upper end of portion 110 of actuating shaft 58′ by a transversely extending pivot pin 120. The toggle handle 118 includes a camming surface 122 which is arranged to engage the upper surface of guide 112 when toggle handle 118 is pivoted to the dotted line position. The camming surface 122 is arranged to cause the actuating shaft 58′ to be pulled upwardly. The arrangement thus far described allows the actuating toggle handle 118 to serve to move the valve to an open position but, also, the toggle handle can be swivelled to extend in substantially any direction relative to the valve 10. Such swivelling movement is permitted and no torque is transmitted to the sealing bellows 36′ because of the arrangement of the previously discussed ball 80′ and balls 94′. The invention has been described with reference to preferred and alternative embodiments. Modifications and alterations are included, insofar as they come within the scope of the claims.

Claims: A valve comprising a valve body (16) defining a valve chamber (18) having inlet and outlet flow passages (20,22) interconnected through a valve seat (28); a valve element (24) carried on an operating stem (30) in said valve chamber (18) for movement towards and away from said seat (28); and means for moving the operating stem (30), the last-mentioned means comprising an actuating shaft (58, 110) carried by said body (16) and having a free end axially aligned with a free end of said operating stem (30); and connecting means joining said actuating shaft (58, 110) to said operating stem (30) for permitting transfer of axial forces therebetween while preventing transfer of torque, said connecting means including a ball (80) positioned between and axially aligned with said free ends of said actuating shaft (58, 110) and said operating stem (30), and retaining means (94, 96) for preventing axial separation of said while allowing free relative rotation therebetween; characterised in that a spring means (86) acts against said ball (80) to apply a biasing force acting to bias said operating stem (30) and said actuating shaft (58, 110) in axially opposite directions. A valve as claimed in claim 1, wherein said retaining means includes at least one second ball (94). A valve as claimed in claim 2, wherein a plurality of second balls is located between said operating stem (30) and said actuating shaft (58, 110). A valve as claimed in claim 3, wherein said second balls (94) are located radially outwardly of said first ball (80). A valve as claimed in claim 4, wherein said second balls (94) are engaged in at least one groove (96) and openings (98) in said operating stem (30) and said actuating shaft (58, 110) or vice versa. A valve as claimed in claim 5, wherein said second balls (96) are positioned circumferentially about said operating stem (30) and are retained in said circumferential groove (96), which is in said operating stem (30), by a sleeve (100). A valve as claimed in any of claims 3 to 6; wherein said second balls (94) are carried in openings (98) in said socket portion. A valve as claimed in any of claims 1 to 7, wherein said actuating shaft (58) or said operating stem (30) carries a socket portion (82) which receives the free end of the other (30 or 58). A valve as claimed in any of claims 1 to 8, wherein said means for producing axial movement of said operating shaft includes threads (66) carried by said actuating shaft (30). A valve as claimed in any of claims 1 to 8, wherein said means for producing axial movement of said actuating shaft (110) includes a pivotal toggle lever (118) drivingly connected to said actuating shaft (110).

Inventors: DANKO OLIVER L, DANKO, OLIVER L.
Applicants: NUPRO CO, NUPRO COMPANY
Application year: 1990
Main classification: F16K41
IPC codes: F16K1, F16K31, F16K41