Abstract:
A quick change coupling arrangement for holding an actuator shaft of a hydraulic dampening unit to a valve shaft of a swing check valve. The coupling arrangement provides knob portions arranged on opposing free ends of the valve shaft and the actuator shaft, which are captured in sandwich fashion between two semi-circular cylindrical shell connectors. An outer sleeve is provided which can be temporarily displaced upward on the actuator shaft during assembly of the shell sections over the knob portions and then slid downward to cover the shell sections and hold the shell connectors together preventing radial departure from the knob portions. A set screw is provided to hold the sleeve in axial fixation with one of the shell connectors.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to valves which have an external actuator shaft connected to a valve closure element, in particular, to a tilted disc check valve having a top mounted hydraulic cylinder which is shaft connected to a tilted disc located within a body of the valve. 
     U.S. Pat. Nos. 4,669,500; 3,789,872; 3,942,551; and 3,785,611 all disclose a check valve which utilizes external shaft connected actuators to influence the movement of a check valve disc. Previously, in a top mounted dashpot arrangement for a check valve, if the dashpot is to be replaced or if any portion of the valve is to be repair, complete disassembly of the structure has been required. A quick replacement of a hydraulic cylinder from the other top mounted dashpot components, for repair or replacement, without having to first remove the tilted disc check valve from the pipeline is desireable. 
     Shaft couplings for valve applications other than check valves are known. U.S. Pat. No. 2,108,234 discloses a stem coupling for attaching adjacent ends of two stems. The mating sections of the coupling are held together by a bolt extending therethrough. U.S. Pat. No. 3,648,718 discloses an assembly for joining a valve actuator shaft with a valve stem. A connector block is used which is internally threaded and formed of two collar pieces which are bolted together and held firm by a jamb nut. U.S. Pat. No. 3,253,610 shows a connecting element having a pair of clamping jaws bolted together and having internal threads therein. 
     U.S. Pat. Nos. 3,353,797; 2,706,997; and 4,616,477, show coupling arrangements engaged to shafts. 
     SUMMARY OF THE INVENTION 
     The present invention concerns an improved shaft coupling arrangement for a valve, particularly for a tilted disc check valve having a top mounted dashpot arrangement shaft connected to the tilted disc. If the hydraulic cylinder is to be replaced or any portion of the valve is to be repaired, complete disassembly of the structure is not required. The unique coupling allows for easy removal of a hydraulic cylinder from other dashpot components, for repair or replacement, without having to first remove the check valve from the pipeline, thus saving maintenance costs and down time. 
     The coupling is capable of taking full compressive and tension forces developed by the check valve during the opening and closing cycle. 
     Due to the inventive assembly of the coupling, critical alignment is eliminated as was heretofore required between the hydraulic cylinder rod (actuator shaft) and the connecting rod (valve shaft), when the hydraulic cylinder rod was coupled by threading to the connecting rod. Previously, if the alignment between these two rods, and the other dashpot components was not perfect, the dashpot assembly would bind or additional frictional forces would be added to the operation of the dashpot assembly. 
     According to the invention, the shaft between the dashpot and the check valve is provided with a slip-over sleeve enclosing a pair of fitted together semi-circular cylindrical segments, each having machined shoulders on the interior surface thereof for cooperatively seating and engaging corresponding shoulders on the joining shaft parts. 
     The invention provides an effective arrangement for coupling any valve including control valves, motor operated valves, gate valves, or the like. According to the invention, opposing actuator shaft and valve shaft provide reduced diameter sections extending into disc-shaped knob portions. The knob portions are arranged closely adjacent. The inventive coupling particularly uses two semi-circular cylinder sections having a grooved formation therein to capture in sandwich fashion the knob portions of the shafts to be joined. An outer cylindrical sleeve, which can be transported upward along one of the shafts until needed, can be slid down over the cylindrical sections, holding the cylindrical sections together in place, binding the facing knob portions of the shaft. A single set screw can be used to attach the outer sleeve to one of the cylinder sections which holds the entire assembly fixed. 
     In another embodiment of the invention, particularly for an orientation wherein the actuator shaft and valve shaft are arranged vertically, the outer sleeve can be sized with an inside diameter greater than the actuator shaft providing a clearance between an outside diameter of the actuator shaft and the inside diameter of the outer sleeve. The outer sleeve further provides on a top end thereof an inwardly directed annular lip which conforms closely to the outside diameter of the actuator shaft. The coupling cylindrical sections are sized having an outer diameter (when assembled) greater than the actuator shaft but still less than the inside diameter of the outer sleeve. This arrangement allows for the outer sleeve to slide down around the cylindrical sections when assembled, with the inwardly directed annular lip resting on a top annular edge of the cylindrical sections exposed around the actuator shaft. Due to this arrangement, the outer sleeve cannot fall downwardly below the cylindrical sections and therefore rests in place, held by gravity. In this arrangement, the set screw can conceivably be eliminated, thus reducing further still the number of parts required to hold the coupling in place. 
     By using the inventive construction, a lightweight, effective coupling arrangement is created, saving weight and cost to manufacture a valve. By contrast, where the prior art used a coupling assembly for capturing ends of a shaft, such as U.S. Pat. No. 2,108,234 or U.S. Pat. No. 3,648,718, a comparatively heavy coupling block using two half coupling blocks with through bolts was used. This structure does not have the lightweight advantage of the present invention. Additionally, considerably more labor is involved to remove two or more bolts than to simply remove one set screw and slide the sleeve to clear the coupling half cylinders. It is also foreseen that coupling blocks using a plurality of bolts are more susceptible to a loosening of the coupling due to loosening of the bolts because of vibrations in use. The present invention in one embodiment utilizes only one set screw, and in another embodiment wherein the sleeve is arranged in vertical orientation, no screwed connecting elements are required at all. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a partial sectional view of a swing check valve having top dashpot mounted components; 
     FIG. 2 is a partial sectional view of the valve assembly of FIG. 1; 
     FIG. 3 is a fragmentary perspective view of a top mounted shaft assembly of FIG. 2; 
     FIG. 4 is an exploded view of a shaft coupling of the present invention; FIG. 5 is a partial sectional view of the coupling assembly of FIG. 4 in partially assembled condition; and FIG. 6 is an elevational view of another embodiment of the coupling and sleeve of FIG. 5. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     FIG. 1 shows a check valve assembly generally at 10 comprising a hydraulic dashpot assembly 14 including a hydraulic cylinder 16. Hydraulic dashpot assemblies for swing check valves are known such as in U.S. Pat. Nos. 3,709,872; 3,942,551; 4,669,500 and 3,785,611. The cylinder and dashpot arrangement is mounted on top of a stand 20 which itself is bolted in sealed fashion to a valve body 26 by bolts 30. The stand 20 comprises a plurality of vertical legs 32. 
     The valve body 26 comprises an annular main body 36 bolted to an annular secondary body 38 by a circular pattern of bolts 40. The main body can terminate in a bolting flange, welding neck, screwing threads, or other connection at end 36a, a flanged connection shown. The secondary body can terminate in a bolting flange, welding neck, screwing threads or other connection at end 38a, a flanged connection shown. Pinched between the main body 36 and the secondary body 38 is a valve seat 42. Pivotally mounted within the main body 36 via a pin 46 is a swing disc 48 which, when swung about the pin 46 counterclockwise according to FIG. 1, seats peripherally around the valve seat 42 to close the main body 36 from the secondary body 38. A select material seal ring 50 can be arranged around a periphery of the swing disc 48, attached by screws 52, to increase sealing and/or increase wear life between the swing disc 48 and the valve seat 42. 
     On a backside 56 of the swing disc 48 is mounted a lug 58 held by a pin 60 to a connector plate 64, at a first end of the connector plate 64. At a second end of the connector plate 64, a pin 70 connects the connector plate 64 to a valve shaft 74. Both the pin 60 and the pin 70 provide pivotal connections. 
     The dashpot assembly 14 provides an actuator shaft 78 proceeding downward from the cylinder 16. The presently preferred material for use in constructing the actuator shaft is 17-4 Ph stainless steel which has the corrosion protection required to withstand the elements of outdoor applications and the high humid conditions found in pump house applications. The actuator shaft 78 is connected inside the cylinder 16 to a piston 80 (see FIG. 2). The piston 80 reciprocates in the cylinder 16 under influence of the hydraulic fluid therein to dampen swinging of the swing disc 48 through the influence of the actuator shaft 78 transferred down through the valve shaft 74. 
     To connect the actuator shaft 78 to the valve shaft 74, a coupling 86 is provided as will be described hereinafter. 
     FIG. 2 shows in more detail the attachment of the hydraulic cylinder 16 to the stand 20. FIG. 2 and FIG. 3 show that four legs 32 are utilized, although two legs can be used or any other number of legs which effectively support the dashpot assembly. One of the legs 32, a leg 32a, is shown partially removed for clarity. The legs 32 support at a top end thereof a platform 90 having bolt holes arranged therethrough. The cylinder 16 is clamped between a top plate 94 and a bottom plate 96 by a plurality of studs 100 having threaded end regions. The studs 100 hold the top plate 94 via a plurality of nuts 104. The bottom plate 96 is held against a bottom of the cylinder 16 by nuts 106. The studs 100 proceed continuously downward through the nuts 106 and have sufficient length to pass through the platform 90, particularly through the bolt holes arranged therethrough, and hold nuts 108 tightly against an underside of the platform 90, abutting the platform 90 at a top end 110 thereof against the bottom plate 96. The actuator shaft 78 proceeds into the cylinder 16 in sealed fashion as is known. The valve shaft 74 proceeds upward through a bushing 116 as shown in FIG. 1. A retaining plate 118 can be mounted with bolts 120 to hold the bushing in place. The bushing 116 can be provided with 0 ring seals (not shown) around its inner and outer diameter for sealing against fluid leakage at the shaft penetration into the valve body 26. 
     FIG. 3 shows the coupling in more detail. The actuator shaft 78 provides at its free end a reduced diameter section 120 followed by a knob portion such as a disc portion 124, both in axial alignment with the shaft 78. The valve shaft 74 provides a reduced diameter section 128 followed by a knob portion such as a disc portion 130. The disc portion 130 and the reduced diameter section 128 are in axial alignment with the valve shaft 74. The valve shaft 74 is in substantial axial alignment with the actuator shaft 78. 
     The coupling provides two shell connectors 140, 142 which substantially form half sections of a circular cylinder. The shell connectors 140, 142 have an outer diameter, when brought together, which is approximately equivalent to an outer diameter of either the actuator shaft 78, the valve shaft 74 or both. The shell connectors 140, 142 have contoured inner surfaces 140a, 142a respective, that conform closely around the reduced diameter sections 120, 128 and the disc portions 124, 130. Because the disc portions have a larger diameter than the reduced diameter sections, shoulder portions 150, 152 are formed thereon which, overlain by the inside surfaces 140a, 142a create an interference which prevents axial separation of the actuator shaft 78 from the valve shaft 74. 
     Shown temporarily displaced upward along an axis of the actuator shaft 78, is a sleeve 160. The sleeve 160 provides at least one hole 162 for insertion of a screw 164 therethrough. 
     FIG. 4 shows in more detail the coupling arrangement 86. The shell connectors 140, 142 have a first cylinder bore 170 having a diameter slightly greater than the reduced diameter sections 120. A cylindrical bore section 172 in the shell connectors 140, 142 has a inside diameter slightly greater than an outside diameter of the disc portions 124, 130. A bottom cylindrical bore section 176 of the shell connectors 140, 142 has an inside diameter slightly larger than the reduced diameter section 128. The sleeve 160 fits over the actuator shaft 78 and has an inside diameter 178 which is slightly greater than an outside diameter of the shell connectors 140, 142 when mounted onto the shafts 78, 74. It is to be noted that the sleeve 160, instead of being slid upwardly onto the actuator shaft 78 to clear the coupling 86, could just as well be arranged to slide downward on the valve shaft 74 to clear the coupling 86. 
     FIG. 5 shows the shell connectors 140, 142 mounted to the shafts 78, 74, with the shell connectors 140, 142 shown in section and the shafts shown in elevation. The inside surfaces 140a, 142a can be adapted to provide some amount of clearances around the disc portions 124, 130 and/or the reduced diameter sections 120, 128 to provide play in the coupling 86 to compensate for any misalignment of the shafts 78, 74. This is an improvement over the prior art shafts which use screwed couplings which require a higher degree of precision and alignment. Once the sleeve 160 is slid down over the shell connectors, 140, 142 the screw 164 can be placed through the hole 162 and threaded into a threaded bore 182 in the shell connector 142. The screw 164, by protruding outwardly of the shell connector 142 into the hole 162, prevents axial sliding of the sleeve 160 with respect to the coupling connector 142 which thus prevents radial separation of the shell connectors 140, 142 by interference with an inside diameter of the sleeve 160. 
     This coupling arrangement provides for a quick disassembly of the hydraulic cylinder from the valve body and stand. If the dashpot is to be replaced or other portion of the dashpot assembly is to be repaired, more extensive disassembly of the structure has been required in the prior art. According to the invention, a quick change coupling is achieved wherein the shaft ends, between the dashpot and the check valve, are provided with the coupling arrangement 86 of the invention. 
     For disassembly, the screw 164 is withdrawn from the threaded bore 182 and the hole 162. Access to the screw and the coupling is made in between the legs 32 of the stand 20. The sleeve 160 is then withdrawn axially upward onto the actuator shaft 78 to clear the shell connectors 140, 142. The shell connectors 140, 142 can then be withdrawn radially away from the shaft 78, 74. The shafts are thereby mechanically disconnected. The nuts 108 can be unscrewed which allows the cylinder 16, the top plate 94, the bottom plate 96, the studs 100 and the nuts 104, 106 to be withdrawn upward with the actuator shaft 78 as a unit. The studs are withdrawn upward through the bolt holes provided in the platform 90. In practice, the couplings and outer sleeve are initially placed or removed from a top side access hole provided in the platform 90 when the top plate 94, the bottom plate 96 are withdrawn with the actuator shaft 78 as a unit. This has been found especially practical when the clearance between the legs 32 is to narrow to place these components therethrough for assembly. 
     Another shaft coupling arrangement 200 is shown in FIG. 6. In this arrangement, an outer sleeve 204 is provided having an annular clearance 206 between an inside diameter of the sleeve 204 and an outside diameter of the actuator shaft 78. The outer sleeve 204 further provides on a top end, an annular lip 208 which proceeds inwardly from the outer sleeve 204 to conform more closely to the outside diameter of the shaft 78. A left shell connector 220 and a right shell connector 222 are provided, similar to the shell connectors, 140, 142 of FIG. 5 except sized to have an outer diameter greater than the actuator shaft 78, but less than an inside diameter of the outer sleeve 204. Thus, when the shell connectors 220, 222 are assembled together as shown in FIG. 6, the outer sleeve 204 can be slid down thereover, as described above with respect to FIG. 5, except that the annular lip 208 will now seat on a top annular edge 224 of the shell connectors 220, 222 as shown dashed in FIG. 6. 
     Also shown in FIG. 6 is threaded bore 230a in right shell connector 222, and threaded bore 230b in left shell connector 220. These threaded bores 230a, 230b can provide the assembly function as described in FIG. 5 for attaching the outer sleeve 204 to one of the bores 230a, 230b to axially retain the outer cylinder in place. However, advantageous to the embodiment of FIG. 6, if the valve shaft 78 is arranged in a vertical orientation, gravity will hold the outer sleeve 204 in place axially thus potentially eliminating the screw as a necessary part. However, of course, the screw can be installed as an additional measure of assembly security. 
     Additionally, by providing threaded bores 230a, 230b in both shell connectors, threaded handling rods 234a, 234b can be utilized as a tool in assembling the coupling. By referring to FIG. 3, it can be seen that manipulation of the coupling between the legs 32 requires much manual dexterity in order clear the shell connectors away from the disc portion 124 in order to disassemble and lift the actuator shaft 78 upward from the valve shaft 74. By providing the handling rods 234a, 234b which can be temporarily screwed into the bores 230a, 230b of the shell connectors 220, 222, or the shell connectors 140, 142 of FIG. 5, these rods 234a, 234b can proceed outwardly through and in between the legs 32 to be effectively manipulated by an assembler or disassembler of the valve. The rods 234a, 234b can be provided with gripping handles similar to a screwdriver or can merely be plain threaded rods cut to an appropriate length. 
     Although the present invention has been described with reference to a specific embodiment, those of skill in the art will recognize that changes may be made thereto without departing from the scope and spirit of the invention as set forth in the appended claims.