Abstract:
A thermostatic mixing valve including a cold water bypass passageway controlled by a pressure-operated check valve that opens upon a failure of a hot water supply to the valve for use with safety devices, such as eyewash and drench shower stations. The thermostatic mixing valve allows the continued delivery of cold water upon a failure of a hot water supply. The lack of hot water causes a cold water valve opening to be closed by a thermal motor, which retracts upon the lack of hot water, yet the bypass passageway is adapted to allow cold water to bypass the thermal motor-controlled cold water valve opening and be directed to the outlet of the valve.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to U.S. Provisional Patent Application No. 61/192,051, filed Sep. 15, 2008, which is incorporated herein by reference. 
    
    
     TECHNICAL FIELD OF THE DISCLOSURE 
     The present disclosure generally relates to fluid control valves and, more particularly, to thermostatic mixing valves that mix hot and cold water supplies to produce tempered water. Even more particularly, the present disclosure relates to a thermostatic mixing valve adapted to allow a cold water bypass upon failure of the hot water supply. 
     BACKGROUND OF THE DISCLOSURE 
     Thermostatic mixing valves (TMVs) are well established and serve to provide a fluid (e.g., water) supply at a desired temperature. TMVs, also referred to as temperature-activated mixing valves, have a temperature responsive thermostat element, or thermal motor, operatively coupled to a valve member controlling fluid flows through hot and cold inlet ports of the valve. The mixed fluids are caused to impinge upon the thermal motor, which in turn expands and contracts and controls the relative proportions of hot and cold fluids passing through the valve. Consequently, when there is an undesirable rise in the temperature of the mixed fluid the thermal motor expands to cause the valve member to reduce the hot flow via the hot inlet port and increase the cold flow via the cold inlet port. Expansion of the thermal motor, therefore, restores the fluid supply temperature condition to that desired, with a converse operation when there is contraction of the thermal motor due to a fall in the mixed fluid temperature. 
     Prior art TMVs that can be used with emergency drench shower stations and eyewash stations are shown in U.S. Pat. Nos. 5,011,074; 5,379,936, 5,647,531; 6,575,377; and 6,732,937. These prior art TMV&#39;s allow a cold-water bypass upon failure of the hot water supply so that emergency drench shower stations and eyewash stations remain supplied with water even upon failure of the hot water supply. 
     What is still desired is a new and improved TMV that can be used to mix hot and cold water supplies to produce tempered water for emergency drench shower stations and eyewash stations. Preferably the thermostatic mixing valve will be adapted to allow a cold-water bypass upon failure of the hot water supply so that emergency drench shower stations and eyewash stations remain supplied with water even upon failure of the hot water supply. 
     SUMMARY OF THE DISCLOSURE 
     The present disclosure provides a new and improved thermostatic mixing valve (TMV) adapted to allow a cold-water bypass upon failure of a hot water supply. According to one exemplary embodiment, the TMV includes a housing having a hot water inlet, a cold water inlet, and a mixed water outlet. A hot water valve seat is positioned in the housing adjacent the hot water inlet, a cold water valve seat is positioned in the housing adjacent the cold water inlet, and a mixing chamber is defined in the housing between the cold water inlet and the hot water inlet. A plunger is received in the mixing chamber and adapted to be moved along a longitudinal axis of the housing between the cold water valve seat and the hot water valve seat. The plunger and the hot water valve seat define a hot water valve opening controlling flow from the hot water inlet to the mixing chamber, and the plunger and the cold water valve seat define a cold water valve opening controlling flow from the cold water inlet to the mixing chamber. 
     The TMV also includes a sensing chamber defined in the housing and connected to the mixed water outlet, and a flow directing assembly positioned in the housing between the mixing chamber and the sensing chamber. A thermal motor is located at least partially within the sensing chamber and extends through the flow directing assembly to the plunger, whereby expansion of the thermal motor causes movement of the plunger towards the hot water valve seat. A plunger return spring biases the plunger toward the cold water valve seat. 
     The flow directing assembly includes an insert defining at least one mixed fluid passageway extending between the mixing chamber and the sensing chamber, and a funnel extending from a first end of the insert into the mixing chamber. The funnel includes a distal end forming the cold water valve seat, and at least one cold water bypass passageway is defined between an outwardly facing surface of the funnel and an inwardly facing surface of the insert for connecting the cold water inlet to the sensing chamber. The cold water bypass passageway is positioned such that cold water can bypass the cold water valve opening and flow from the cold water inlet to the sensing chamber. The TMV also includes a check valve adapted to normally close the cold water bypass passageway and only allow flow through the bypass passageway and into the sensing chamber upon fluid pressure within the sensing chamber dropping below the pressure in the cold water inlet. 
     Among other aspects and advantages, the new and improved TMV of the present disclosure allows a cold-water bypass upon failure of the hot water supply so that emergency drench shower stations and eyewash stations remain supplied with water even upon failure of the hot water supply. 
     Additional aspects and advantages of the present disclosure will become readily apparent to those skilled in this art from the following detailed description, wherein only an exemplary embodiment of the present disclosure is shown and described, simply by way of illustration of the best mode contemplated for carrying out the present disclosure. As will be realized, the present disclosure is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, all without departing from the disclosure. Accordingly, the drawings and description are to be regarded as illustrative in nature, and not as restrictive. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       Reference is made to the attached drawings, wherein elements having the same reference character designations represent like elements throughout, and wherein: 
         FIG. 1  is a top and side perspective view of an exemplary embodiment of a thermostatic mixing valve (TMV) constructed in accordance with the present disclosure; 
         FIG. 2  is a side elevation view of the TMV of  FIG. 1 ; 
         FIG. 3  is a sectional view of the TMV of  FIG. 1 ; 
         FIG. 4  is an enlarged sectional view, in perspective, of a portion of the TMV of  FIG. 1 ; 
         FIG. 5  is a further enlarged sectional view of a portion of the TMV of  FIG. 1 ; 
         FIG. 6  is an exploded top and side perspective view of the TMV of  FIG. 1 ; 
         FIG. 7  is an enlarged, exploded top and side perspective view of some of the internal components of the TMV of  FIG. 1 , including a cold water bypass poppet, an insert, and a funnel; 
         FIG. 8  is a further enlarged top perspective view of the cold water bypass poppet; 
         FIG. 9  is a further enlarged sectional view of the cold water bypass poppet, the insert, and the funnel; 
         FIG. 10  is an enlarged sectional view of a portion of the TMV of  FIG. 1 , wherein hot water failure conditions are illustrated and the cold water bypass poppet is shown in an open position; 
         FIG. 11  is a further enlarged sectional view of a portion of the TMV contained within circle “ 11 ” of  FIG. 10 , wherein the cold water bypass poppet is shown in an open position; 
         FIG. 12  is a sectional view of another exemplary embodiment of a TMV constructed in accordance with the present disclosure; 
         FIG. 13  is a sectional view, in perspective, of the TMV of  FIG. 12 ; 
         FIG. 14  is an enlarged, exploded top and side perspective view of some of the internal components of the TMV of  FIG. 12 , including a cold water bypass poppet; 
         FIG. 15  is a sectional view of the TMV of  FIG. 12 , wherein hot water failure conditions are illustrated and the cold water bypass poppet is shown in an open position; and 
         FIG. 16  is a further enlarged sectional view of a portion of the TMV contained within circle “ 16 ” of  FIG. 15 , wherein the cold water bypass poppet is shown in an open position. 
     
    
    
     DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS 
     Referring to  FIGS. 1-12 , an exemplary embodiment of a new and improved thermostatic mixing valve (TMV)  10  according to the present disclosure is shown. Among other benefits, the new and improved TMV  10  of the present disclosure allows a cold-water bypass upon failure of a hot water supply so that emergency drench shower stations and eyewash stations connected to the TMV remain supplied with water even upon failure of the hot water supply. Without the bypass no water will pass through the TMV since the lack of hot water cause the cold water valve member to be closed. 
     The TMV  10  includes a housing  16  having a first inlet  18  for receiving a first fluid and a second inlet  20  for receiving a second fluid, and an outlet  22  for discharging a mixture of the first and the second fluids. In the exemplary embodiment shown, the first inlet  18  is designed to receive hot water, the second inlet  20  is designed to receive cold water, and tempered water is discharged from the outlet  22 . 
     As shown best in  FIGS. 4-6  and  10 , first and second spaced-apart seats  24 ,  26  are received in the housing  16  and define a mixing chamber  28  between the first and the second inlets  18 ,  20 . In the exemplary embodiment shown, the first seat comprises a hot water seat  24  positioned adjacent the hot water inlet  18 , while the second seat comprises a cold water seat  26  positioned adjacent the cold water inlet  20 . The cold water seat  26  is located on an end  102  of a flow directing assembly  100  that separates the mixing chamber  28  from a sensing chamber  12  of the housing  16 . The sensing chamber  12  is connected to the outlet  22  of the housing  16 . 
     The TMV  10  also includes a plunger  36  received in the mixing chamber  28  that is movably between the first and the second seats  24 ,  26 . The plunger  36  and the first seat  24  define a first valve opening  38  (i.e., hot water valve opening) that controls flow from the first inlet  18  to the mixing chamber  28 , and the plunger  36  and the second seat  26  define a second valve opening  40  (i.e., cold water valve opening) that controls flow from the second inlet  20  to the mixing chamber  28 . A spring  42  biases the plunger  36  away from the first seat  24  to open the first valve opening  38  and close the second valve  40  opening (i.e., more hot water and less cold water). 
     A thermostat element, or thermal motor  14 , is at least partially located within the sensing chamber  12  and extends through the flow directing assembly  100  to the plunger  36 . The thermal motor  14  includes a temperature responsive (expandable) piston  44  that extends from a cylinder  46  connected by a flange  48  to a casing  50 . In general, the casing  50  contains a thermally expandable wax material, which pushes against the piston  44  to increase the overall length of the thermal motor  14  as a temperature of the wax increases. Expansion of the thermal motor  14 , therefore, causes movement of the plunger  36  against the spring  42  and towards the first seat  24 , such that the first valve opening  38  is closed and the second valve opening  40  is opened (i.e., less hot water and more cold water). The thermal motor  14 , therefore, controls the temperature of the mixed fluid. 
     As shown best in  FIGS. 3-5 , the flow directing assembly  100  includes a first end  102  received in the mixing chamber  28  and extending past the cold water inlet  20 , a second end  104  received in the sensing chamber  12 , a sidewall  106  extending between the first and the second ends  102 ,  104 , a mixed water passageway  108  extending between the first and the second ends  102 ,  104  to provide fluid communication between the mixed chamber  28  and the sensing chamber  12 , and a cold water bypass passageway  110  extending from the sidewall  106  adjacent the first end  102  for providing fluid communication between the cold water inlet  20  and the sensing chamber  12 . 
     In the exemplary embodiment shown, the flow directing assembly  100  includes a cylindrical insert  112  extending from the sensing chamber  12  and including a tubular outer wall  114 , a tubular inner wall  116 , and a tubular intermediate wall  118 , wherein the mixed fluid passageway  108  is defined between the inner wall  116  and the intermediate wall  118  and within the inner wall  116  (i.e., between the inner wall  116  and the thermal motor  14 ). The tubular walls  114 ,  116 ,  118  are connected by radial ribs  120 , as shown best in  FIGS. 7 and 9 . The flow directing assembly  100  also includes a funnel  130  extending from the intermediate wall  118  of the insert  112  and into the mixing chamber  28 , and the cold water bypass passageway  110  is defined between an outwardly facing surface  134  of the funnel  130  and the outer wall  114  of the insert  112 , as shown best in  FIGS. 3-5 . The insert  112  includes ports  122  between the outer wall  114  and the intermediate wall  118  that connect the bypass passageway  110  directly to the sensing chamber  12 . An inwardly facing surface  132  of the funnel  130  is adapted to direct fluid from the mixing chamber  28  to the mixed water passageway  108  of the insert  112 . The funnel  130  is also shown in  FIGS. 7 and 9 . 
     In the exemplary embodiment shown, the outer wall  114  of the insert  112  is secured to the housing  16  with screw threads, and the funnel  130  is secured to the intermediate wall  118  of the insert  112  with screw threads. In an alternative embodiment, the insert  112  and the funnel  130  could be attached together in other ways, such as by welding, or could simply be formed together as a single unitary piece. In addition, the insert  112  could be secured to the wall of the housing  16  in other ways, such as by welding, or could simply be formed together as a single unitary piece with the housing. 
     The TMV  10  also includes a check valve  140  adapted to normally close the bypass passageway  110  of the flow directing assembly  100 . The check valve  140  is adapted to open and allow flow directly from the cold water inlet  20 , through the bypass passageway  110 , to the sensing chamber  12  in response to a predetermined increase in pressure drop between the cold water inlet  20  and the sensing chamber  12 . The check valve  140  can be of any type sensitive to pressure. In the exemplary embodiment shown, the funnel  130  includes a bypass valve seat  136  on the outwardly facing surface  134  and the check valve  140  includes a poppet  142  and a spring  144 , the spring  144  being positioned to bias the poppet  142  against the bypass valve seat  136  to close the bypass passageway  110 , as shown best in  FIGS. 3-5 . 
     As shown best in  FIGS. 3-7 , the flow directing assembly  100  also includes a flow-directing element  150  extending from the insert  112  into the sensing chamber  12  that directs fluid flow from the mixing fluid passageway  108  towards the thermal motor  14 . In the exemplary embodiment shown the flow-directing element  150  is secured between a shoulder of the housing  16  and the insert  112 , and the spring  144  of the check valve  140  extends between the flow directing element  150  and the poppet  142 . In the exemplary embodiment shown, the poppet  142  is annular, coaxial with the longitudinal axis of the housing  16 , and coaxially aligned between the funnel  130  and the insert  112 . The check valve  140  includes multiple springs  144  received on prongs  146  of the annular poppet  142 , as shown best in  FIGS. 6 and 7 . As shown in  FIGS. 8 and 9 , the annular poppet  112  also includes extensions  148  located between the prongs  146  which help to maintain the poppet  112  correctly positioned within the outer wall  114  of the insert  112 . 
     The plunger  36 , best shown in  FIGS. 3-7 , includes a socket  56  extending along the longitudinal axis of the housing within the inner wall of the insert. The socket  56  has openings for allowing flow through the insert, and the thermal motor  14  is received in the socket  56 . The casing  50  of the thermal motor  14  is partially received in the socket  56  of the plunger  36 , and at least a portion of the casing  50  of the thermal motor  14  is received in the sensing chamber  12 . 
     The plunger  36  also includes coaxial inner and outer tubular walls  60 ,  62  connected by a lateral wall  64 . Radial fins  67  are provided between the inner and outer walls  60 ,  62 , and the lateral wall  64  includes apertures  66  for allowing the mixture of fluid flow from the hot and the cold valve openings  38 ,  40 . A bottom edge of the outer wall  62  forms the hot water valve opening  38  in combination with the hot water seat  24 , and a top edge of the outer wall  62  fauns the cold water valve opening  40  in combination with the cold water seat  26 . 
     Although not required, in the exemplary embodiment shown the housing  16  further comprises an annular first inlet chamber  74  connected to the first inlet  18  and surrounding the first valve sea  24 , an annular second inlet chamber  76  connected to the second inlet  20  and surrounding the second valve seat  26 . These chambers are shown in  FIGS. 1-5  of the drawings. 
     Although not required, in the exemplary embodiment shown the TMV  10  also includes an adjustable motor positioning assembly including a setscrew  90 , a case  92 , a spring  94 , a cap  96 , and a retainer ring  98 . The TMV  10  further includes numerous o-rings providing fluid-tight seals between the assembled parts of the TMV. For example, an o-ring is provided between the annular poppet  112  and the outer wall  114  of the insert  112 , and an o-ring is provided between the outer wall  114  of the insert  112  and the housing  16 . An o-ring is also provided between the plunger  36  and the housing  16  to create a seal between the inlets  18 ,  20 . as shown best in  FIG. 3-5 . 
     In  FIGS. 10 and 11  a hot water failure condition is illustrated and the cold water bypass poppet  142  is shown in an open position During a hot water failure, the thermal motor  14  cools and shrinks such that the cold water valve opening  40  closes completely. No water is then delivered to the sensing chamber such that pressure within the sensing chamber  12  drops below pressure at the cold water inlet  20 . The pressure differential between the cold water inlet  20  and the sensing chamber  12  then forces the poppet  142  towards the sensing chamber  12  and off of the bypass valve seat  136  of the funnel  130 , so that the bypass passageway  110  is opened. Arrows labeled “Bypass Flow” illustrate the flow of water from the cold water inlet  20 , through the bypass passageway  110 , to the sensing chamber  12 . 
       FIGS. 12-15  show another exemplary embodiment of a TMV  200  according to the present disclosure. The TMV  200  is similar to the TMV  10  of  FIGS. 1-11  such that similar elements have the same reference numerals. The TMV  200  of  FIGS. 10-15 , however, does not include the flow-directing element  150  extending from the second end  104  of the flow directing assembly  100 . Instead, an annular plate  202  is secured to a second end  104  of the assembly  100 , closing the ports  122  located between the outer wall  114  and the intermediate wall  118 , and the funnel  130  includes ports  238  beyond the bypass valve seat  136  connecting the bypass passageway  110  to the mixed flow passageway  108 . In  FIGS. 14 and 15 , arrows labeled “Bypass Flow” illustrate the flow of cold water through the ports  238  during a hot water failure condition. 
     The present disclosure, therefore, provides a new and improved thermostatic mixing valve. It should be understood, however, that the exemplary embodiment described in this specification has been presented by way of illustration rather than limitation, and various modifications, combinations and substitutions may be effected by those skilled in the art without departure either in spirit or scope from this disclosure in its broader aspects and as set forth in the appended claims. Accordingly, other embodiments are within the scope of the following claims. In addition, the mixing valve disclosed herein, and all elements thereof, are contained within the scope of at least one of the following claims. No elements of the presently disclosed thermostatic mixing valve are meant to be disclaimed.