Abstract:
A sealing device for a modulating valve of the type having a valve body defining a flow passage, an inlet and outlets, a valve displaceable in the flow passage, and an actuator having an actuator rod rotatably coupled to the valve for displacing the valve in the flow passage. The sealing device comprises a body surrounding the actuator rod. A connector is adapted to secure the body of the sealing device to the valve body. Seals are provided between the body of the sealing device and the actuator rod arid between the body of the sealing device and the valve body, to prevent fluid flow therebetween. The body of the sealing device and the seals are adapted to conceal and contain fluid leaks, whereby no fluid is lost due to a leaking modulating valve.

Description:
TECHNICAL FIELD 
     The present invention generally relates to modulating valves used in refrigerant circuits and, more particularly, to a sealing device for preventing refrigerant losses through leaks of modulating valves. 
     BACKGROUND ART 
     Various types of modulating valves, such as incrementally positionable valves, are widely used in refrigerant circuits for refrigeration and air-conditioning systems. For instance, modulating valves are frequently used at nodes of diverging loops of circuits to provide refrigerant for heat reclaim or for defrosting evaporators of refrigeration display units. Such valves are also used in split condensers and hot-gas applications. These valves are used to control the ratios of refrigerant conveyed to the various elements of the circuits or to control the flow of refrigerant through the lines. The modulating action of the valves prevents water hammer in the refrigerant lines, which could have adverse effects on the various elements of such circuits. Mueller™ Refrigeration Co. provides such modulating valves, under the name Cycle Master™. 
     However, the modulating valves of refrigerant circuits are subjected to the harsh conditions typical to circuits. For instance, the refrigerant in refrigerant circuits is at relatively high temperatures and fluctuates between large temperature variations. Furthermore, the refrigerant is compressed to relatively high pressures, and the modulating valves are often employed to create pressure drops in the circuits. Finally, the refrigerants typically known and used are often of a corrosive nature. 
     For these reasons, some modulating valves have been known to leak at the stem. A plurality of negative effects results from such leaks. For instance, substantial losses of refrigerant can cause inefficient refrigeration cycles and shutdowns. Furthermore, the refrigerants are often harmful to the environment, and refrigerant losses to the environment must be prevented. Finally, downtimes are very costly and are risky as the contents of the refrigeration display units cannot be subjected to temperature increases without the risk of being fouled. 
     SUMMARY OF INVENTION 
     It is a feature of the present invention to provide a sealing device for preventing refrigerant loss through a modulating valve. 
     According to the above features of the present invention, from a broad aspect, the present invention provides a sealing device for a modulating valve of the type having a valve body defining a flow passage, at least one inlet and one outlet, a valve displaceable in the flow passage to control an opening of the flow passage, and actuation means having an actuator rod rotatably coupled to the valve at an exterior of the valve body for displacing the valve in the flow passage, the sealing device comprising a body surrounding the actuator rod of the modulating valve, the body defining a receptacle for accommodating a coupling between the actuator rod and the valve so as not to impede on the actuation of the valve by the actuator rod; connection means adapted to secure the body of the sealing device to the valve body, the connection means being a tubular member being adapted to be threadingly engaged to the valve body, the tubular member compressing the body of the sealing device against the valve body such that a first one of the sealing means is squeezed between the body of the sealing device and the valve body; and sealing means between the body of the sealing device and the actuator rod and between the body of the sealing device and the valve body, to prevent fluid flow therebetween, said body of the sealing device and said sealing means being adapted to conceal and contain fluid leaks between one of the valve and the actuator rod, and the valve body, whereby no fluid is lost due to a leaking modulating valve. 
     Further in accordance with the present invention, there is provided a sealing device for a modulating valve of the type having a valve body defining a flow passage, at least one inlet and one outlet, a valve displaceable in the flow passage to control an opening of the flow passage, and actuation means having an actuator rod rotatably coupled to the valve at an exterior of the valve body for displacing the valve in the flow passage, the sealing device comprising a body surrounding the actuator rod of the modulating valve, the body defining a receptacle for accommodating a coupling between the actuator rod and the valve so as not to impede on the actuation of the valve by the actuator rod; connection means adapted to secure the body of the sealing device to the valve body; sealing means between the body of the sealing device and the actuator rod and between the body of the sealing device and the valve body, with the sealing means between the, body of the sealing device and the rod being packing, to prevent fluid flow therebetween, said body of the sealing device and said sealing means being adapted to conceal and contain fluid leaks between one of the valve and the actuator rod, and the valve body, whereby no fluid is lost due to a leaking modulating valve; and a cover member connectable to an end of the body of the sealing device distal from the valve body, the cover member having a sleeve accommodatable between the body of the sealing device and the actuator rod to contain the packing therebetween. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       A preferred embodiment of the present invention will now be described with reference to the accompanying drawings in which: 
         FIG. 1  is a front elevational view, partly sectioned and fragmented, of a modulating valve having a sealing device constructed in accordance with the present invention; 
         FIG. 2  is an exploded cross-sectional view of the sealing device in accordance with the present invention; 
         FIG. 3  is a longitudinal cross-sectional view of a tube portion of the sealing device; 
         FIG. 4  is a front elevational view, partly sectioned and fragmented, of the modulating valve having a sealing device constructed in accordance with a second embodiment of the present invention; 
         FIG. 5  is an exploded cross-sectional view of the sealing device constructed in accordance with the second embodiment of the present invention; and 
         FIG. 6  is a longitudinal cross-sectional view of a tube portion of the sealing device constructed in accordance with the second embodiment of the present invention. 
     
    
    
     DESCRIPTION OF PREFERRED EMBODIMENTS 
     Referring to the drawings, and more particularly to  FIG. 1 , a modulating valve is generally shown at  10 . The modulating valve  10  is of the three-way type, and has an inlet  12  and outlets  14  and  16 . The modulating valve  10  has an actuator stem  18  protruding outwardly from a connection collar  20 . The actuator stem  18  is connected to a ball (not shown) in the modulating valve  10 , and is actuated to control the position of the ball in the modulating valve  10 . For instance, a modulating action on the actuator stem  18  can be performed to control the outputs of the outlets  14  and  16  with respect to one another, or to create a pressure differential between the inlet  12  and the outlets  14  and  16 . The connection collar  20  has a threaded peripheral surface  21 . 
     The actuator stem  18  is actuated by an actuator  22  connected to the actuator stem  18  by an actuation rod  24 . As shown in  FIGS. 1 and 2 , the actuation rod  24  has a head portion  25  having a mating hole  27 , to be rotatably coupled to the actuator stem  18 . Returning to  FIG. 1 , the actuator  22  is mounted to the body of the modulating valve  10  by a support bracket  26 . The support bracket  26  has a first leg  28  riding on the outlet pipe  14  of the modulating valve and a second leg  30  secured to the connection collar  20  by a pair of fasteners  32 , which are operatively engaged to the threaded peripheral surface  21 . The actuator  22  is typically a Belimo™ or a Neptroric™ motor, whereas the modulating valve  10  is, for instance, a Mueller™ Refrigeration Cycle Master™ valve. Stops  34  (only one of which is shown) are provided on a top annular surface  36  of the connection collar  20 , and coact with a radial pin (not shown) on the actuator stem  18  to typically limit the angular displacement of the ball to 90°. 
     Leaks have been known to occur between the actuator stem  18  and the connection collar  20 . Therefore, a sealing device in accordance with the present invention is generally shown at  40 , and is mounted to the modulating valve  10  so as to prevent losses of refrigerant from the modulating valve  10 . 
     The sealing device  40 , as best shown in  FIGS. 2 and 3 , has a tube portion  42 , a connector portion  44 , actuation rod seals  46  and a valve seal  48 . The tube portion  42  is shown having a tubular body  50  having a top end  51 , a bottom end  52 , and an outer peripheral surface  53  with a shoulder  54 , generally in a middle area of the tubular body  50 . The tubular body  50  has a through bore  56  and a first counterbore  58  concentric with the through bore  56 . A second counterbore  60  of larger diameter is concentric with the first counterbore  58 . Three radial grooves  62  are positioned in the through bore  56  and are adapted to each receive one of the actuation rod seals  46 . The seals  46  are typically of materials well suited for high-temperature refrigerant. For instance, the seals  46  can be in neoprene, nitrile, polytetrafluoroethylene (PTFE), Hypalon™, or any other material well suited for the applications of the modulating valve  10 , and may be lip seals, O-rings or any other suitable type of seal. An annular groove  64  is positioned on the bottom end  52  of the tubular body  50 , and receives therein the valve seal  48 . Similarly to the actuation rod seals  46 , the valve seal  48  is made of materials well suited for refrigerant at high temperatures, such as neoprene, nitrile, PTFE, Hypalon™, etc., and can be a lip seal, an O-ring, etc. 
     The connector portion  44  has a tubular body  66  having a top end  68 , a bottom end  70 , and a through bore  72 . An inner lip  74  projects radially inwardly in the through bore  72  at the top end  68  of the tubular body  66 . The tubular body  66  is tapped at the bottom end  70 . 
     Now that the various elements of the sealing device  40  have been described in detail, the assembly of the sealing device  40  to the modulating valve  10  will be described. Prior to the actuator  22  being mounted to the modulating valve  10 , the tube portion  42  of the sealing device  40  is axially slid onto the actuation rod  24 . The tube portion  42  is sized such that the first counterbore  58  thereof snugly receives the head portion  25  of the actuation rod  24 . In doing so, the actuation rod seals  46  seal the passage between the through bore  56  of the tube portion  42  and the actuation rod  24 . 
     The tube portion  42  is positioned on the top annular surface  36  of the connection collar  20 , with the bottom end  52  of the tube portion  42  sitting thereon. Accordingly, the valve seal  48  seals the tube portion  42  to the connection collar  20 . In positioning the actuation rod  24  on the connection collar  20 , the mating hole  27  is rotatably coupled to the actuation stem  18 . The actuation rod  24  is free to rotate with respect to the tube portion  42 . The second counterbore  60  accommodates the stops  34  and the radial pin (not shown) of the actuator stem  18 . The radial pin is free to move in the second counterbore  60 . 
     Thereafter, the connector portion  44  is threadingly engaged through its tapped portion at the bottom end  70  thereof to the threaded peripheral surface  21  of the connection collar  20 . The connector portion  44  is sized so as to snugly receive a bottom portion of the tube portion  42 . More precisely, the inner lip  74  of the connector portion  44  abuts against the shoulder  54  on the peripheral surface  53  of the tube portion  42 . Therefore, as the connector portion  44  is tightened onto the connection collar  20 , the tube portion  42  is pulled downwardly so as to squeeze the valve seal  48 , thereby securing the sealing therebetween. 
     It is pointed out that the fasteners  32  must be engaged on the connection collar  20  prior to the connector portion  44  being secured thereto. Furthermore, the second leg  30  of the support bracket  26  may be secured to the modulating valve  10  in a first step, to then have the second leg  30  and the remainder of the support bracket  26  added thereto via bolt and nut  38 , once the sealing device  40  has been mounted onto the modulating valve  10 . The sealing device  40  does not prevent leaks between the actuator stem  18  and the connection collar  20 . However, refrigerant leaks therethrough are concealed and contained by the sealing device  40  such that no refrigerant is lost because of a leaking modulating valve. 
     The modulating valves  10  can be retrofitted with the sealing device  40 . Therefore, the sealing device  40  may be sold separately from the modulating valve  10  as a repair kit. The installation of the sealing device  40  on the modulating valve  10  is readily achieved, whereby the downtime for attending to the modulating valve  10  in case of a leak is greatly reduced. 
     Referring now to  FIGS. 4 ,  5  and  6 , a second embodiment of the present invention is shown, in which packing is used instead of the seals  46  to seal the actuation rod  24 . The sealing device in accordance with the second embodiment of the present invention is generally shown at  40 ′. For clarity purposes, like elements between the first embodiment of  FIGS. 1  to  3  and the second embodiment of  FIGS. 4  to  6  will bear the same reference numerals. Additional elements will have their reference numerals primed. As best seen in  FIG. 5 , the sealing device  40 ′ has a tube portion  42 ′, the connector portion  44 , packing  46 ′, the valve seal  48  and a packing retainer  49 ′. 
     Referring to  FIG. 6 , the tube portion  42 ′ is relatively similar to the tube portion  42  of FIG.  3 . However, in addition to the tubular body  50  having the top end  51  and the bottom end  52 , the peripheral surface  53 , the shoulder  54 , the through bore  56 , the first counterbore  58 , and the second counterbore  60 , the tube portion  42 ′ has a third counterbore  61 ′ concentric with the through bore  56  and extending therein from the top end  51  of the tube portion  42 ′. Furthermore, a second annular groove  65 ′ is defined at the top end  68  of the tube portion  42 ′. An upper portion of the peripheral surface  53  is threaded. 
     Still referring to  FIG. 6 , the packing retainer  49 ′ is shown having a first tubular body  80  and a second tubular body  82 . The second tubular body  82  is concentrically disposed with respect to the first tubular body  80 . The first tubular body  80  and the second tubular body  82  share a top end  84 . However, the second tubular body  82  is shorter than the first tubular body  80 . An underside  86  of the top end  84  defines an annular protrusion  88 . The first tubular body  80  is tapped, so as to threadingly engage with the threads on the upper portion of the peripheral surface  53  of the tube portion  42 ′. 
     The sealing device  40 ′ is mounted to the modulating valve  10  by the connector portion  44 , as described for the first embodiments of  FIGS. 1  to  3 . However, the sealing of the actuation rod  24  is performed by putting packing  46 ′ into the third counterbore of the tube portion  42 ′. Thereafter, the packing retainer)  49 ′ is screwed onto the tube portion  42 ′, and the second tubular portion  82  compresses the packing  46 ′ so as to ensure the integrity of the sealing between the actuation rod  24  and the tube portion  42 ′. The annular protrusion  88  ensures the precise positioning of the packing retainer  49 ′ on the tube portion  42 ′ by nesting into the second annular groove  65 ′. Various types of packing  46 ′ may be used, such as carbon/graphite packing, synthetic braids coated with PTFE, PTFE or other similar materials. 
     It is within the ambit of the present invention to cover any obvious modifications of the embodiments described herein, provided such modifications fall within the scope of the appended claims.