Patent Publication Number: US-2007119501-A1

Title: Pressure balance valve

Description:
BACKGROUND AND SUMMARY OF THE INVENTION  
      The present invention relates to generally to a mixing valve and, more particularly, to a spool type pressure balance valve.  
      Mixing valves including pressure balancing devices are well known in the art. Such prior art mixing valves often pressure balance the hot and cold water supplies and provide for adjustment of the temperature in a mixing valve housing with a temperature adjustment control. One such mixing valve is disclosed in U.S. Pat. No. 5,725,010, the disclosure of which is expressly incorporated by reference herein.  
      However, there remains a need for a cost efficient and lightweight mixing valve. More particularly, there is a need for a cost efficient and lightweight spool type pressure balance valve which provides improved sealing.  
      According to an illustrative embodiment of the present disclosure, a valve is provided for balancing pressure between a first fluid and a second fluid. The valve includes a valve body having a first fluid inlet for receiving the first fluid, a second fluid inlet for receiving the second fluid, a first fluid outlet, a second fluid outlet, and an internal chamber in fluid communication with the first fluid inlet, the second fluid inlet, the first fluid outlet, and the second fluid outlet. A first valve member is molded from a polymer and is positioned within the chamber. The first valve member includes an inner surface defining an internal passage in fluid communication with the first fluid supply, the second fluid supply, the first fluid outlet, and the second fluid outlet. A second valve member is at least partially disposed within the internal passage of the first valve member, and is slidably moveable relative to the first valve member. The second valve member includes an outer surface, a first fluid conduit in fluid communication with the first fluid supply and the first fluid outlet, and a second fluid conduit separated from the first fluid conduit and in fluid communication with the second fluid supply and the second fluid outlet. The outer surface of the second valve member and the inner surface of the first valve member are machined to substantially the same dimension to provide a movable seal between the second valve member and the first valve member and thereby prevent the passage of fluid from the first fluid conduit to the second fluid conduit.  
      Illustratively, the first valve member and said second valve member further each include a plurality of apertures, wherein the apertures of the first valve member and the second valve member are selectively alignable to control the flow of water to the first and second fluid outlets. Further illustratively, at least one of the plurality of apertures are elongated. Illustratively, at least one of the plurality of apertures of the second valve member includes radially outwardly extending wall. In another illustrative embodiment, at least one of the plurality of the apertures of the first valve member includes tapered outer surfaces. In an illustrative embodiment, the second valve member further includes opposing ends, and a plurality of ribs on the ends configured to couple to a holder. Illustratively, the first valve member includes a substantially cylindrical wall defining the inner surface. Further illustratively, the first valve member includes a plurality of annular members extending radially outwardly from the substantially cylindrical wall. The first valve member further illustratively includes sealing rings supported by the annular members. Illustratively, the second valve member is molded from a polymer.  
      According to another illustrative embodiment of the present disclosure, a method of forming a pressure balance valve assembly is provided. The method includes the steps of injection molding a first valve member from a polymer, the first valve member including an inner surface defining an internal passage, and precision machining the inner surface of the first valve member to a first diameter. The method further comprises the steps of injection molding a second valve member from a polymer, the second valve member including an outer surface, and precision machining the outer surface of the second valve member to a second diameter, wherein the second diameter is substantially equal to the first diameter.  
      In an illustrative embodiment, the difference between the first diameter and the second diameter is no more than approximately 0.002 inches. Illustratively, the method comprises the additional step of subjecting the second valve member and the first valve member to a first fluid, wherein the first valve member and the second valve member expand before precision machining either one of the first or said second valve members. Further illustratively, the method comprises the additional step of providing a multiple valve member mold, and simultaneously injection molding said first and said second valve members within the multiple valve member mold. In a further illustrative embodiment, the method comprises the additional step of inserting the second valve member within the first valve member for sliding movement, wherein the outer surface of the second valve member seals against the inner surface of the first valve member.  
      According to another illustrative embodiment of the present disclosure, a valve assembly includes a sleeve molded from a polymer and having a precision machined inner surface defining a passage. A spool includes a precision machined outer surface which sealingly engages the inner surface of the sleeve when said spool is received within the passage of the sleeve.  
      Illustratively, the spool further includes a cylindrical wall defining first and second fluid conduits and a plurality of apertures. Further illustratively, at least one of the plurality of apertures is elongated. In another illustrative embodiment, at least one of the plurality of the apertures includes tapered outer surfaces. Illustratively, the spool is molded from a polymer.  
      Additional features and advantages of the present invention will become apparent to those skilled in the art upon consideration of the following detailed description of the illustrative embodiment exemplifying the best mode of carrying out the invention as presently perceived. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The detailed description of the drawings particularly refers to the accompanying figures in which:  
       FIG. 1  is a perspective view of an illustrative embodiment valve;  
       FIG. 2  is a cross-sectional view of the valve of  FIG. 1  taken along line  2 - 2 , showing the valve body and the first and second valve members;  
       FIG. 3  is an exploded perspective view of the valve of  FIG. 1 ;  
       FIG. 4  is a side elevation view of the first valve member of the valve of  FIG. 3 ;  
       FIG. 5  is a side elevation view of the second valve member of the valve of  FIG. 3 ; and  
       FIG. 6  is a flow chart showing an illustrative embodiment method of forming the valve of  FIG. 1 .  
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS  
      Referring initially to  FIGS. 1 and 2 , a mixing valve  10  according to the present disclosure includes a pressure balance proportioning valve  12  having a valve body  14  configured to receive a first valve member  16  and a second valve member  18 . The valve body  14  may be received within a housing of the type detailed in U.S. Pat. No. 5,725,010, the disclosure of which has been expressly incorporated by reference herein. Illustratively, valve body  14  includes a first valve body portion  20  and a second valve body portion  22 . Coupling first valve body portion  20  to second valve body portion  22  defines an internal chamber  24  for receiving the first and second valve members  16  and  18 , respectively. Locating pins  26  may be received within apertures  28  to facilitate proper orientation of first valve body portion  20  relative to second valve body portion  22  ( FIG. 3 ).  
      First valve body portion  20  includes a first fluid inlet  30  and a first fluid outlet  32 . Similarly, second valve body portion  22  includes a second fluid inlet  34  and a second fluid outlet  36 . The first and second fluid inlets  30  and  34  illustratively comprise two laterally spaced apart, downwardly extending hollow tubular extensions configured to receive hot and cold water, respectively. Conventional check valves (not shown) may be received within the inlets  30  and  34  to prevent cross-flow of water from the first fluid inlet  30  into the second fluid inlet  34 , and vice versa.  
      The first and second fluid outlets  32  and  36  illustratively comprise two laterally spaced apart, upwardly extending hollow tubular extensions configured to dispense hot and cold water, respectively. The fluid outlets  30  and  36  are configured to receive seal elements or seats which are biased upwardly by springs (not shown). The seats and springs may be of conventional design and illustratively of the type detailed in U.S. Pat. No. 5,725,010.  
      First valve member or sleeve  16  is non-rotatably disposed within internal chamber  24 . As shown in  FIGS. 2-4 , first valve member  16  includes a substantially cylindrical wall  38  having an inner surface  40  which defines an internal passage  42  with an inner diameter d 1 . Cylindrical wall  38  of first valve member  16  also includes an outer surface  44 . A plurality of annular members  46   a ,  46   b ,  46   c ,  46   d ,  46   e  extend radially outwardly from the outer surface  44  and each include a receiving groove  47   a ,  47   b ,  47   c ,  47   d ,  47   e , respectively. First valve member  16  further includes a plurality of axially spaced apertures  48   a ,  48   b ,  48   c , and  48   d . Apertures  48   a  are aligned with first fluid inlet  30 , apertures  48   b  are aligned with first fluid outlet  32 , apertures  48   c  are aligned with second fluid outlet  36 , and apertures  48   e  are aligned with second fluid inlet  34 . The apertures  48  illustratively include tapered or beveled surfaces  49  and are circumferentially elongated for increased fluid flow. Illustratively, a rib  50  may extend outwardly from the outer surface  44  and is a result of a gate formed during the injection molding process described herein.  
      As illustrated in  FIGS. 2 and 3 , first valve member  16  further illustratively includes sealing rings  52   a ,  52   b ,  52   c ,  52   d , and  52   e  which are respectively received within grooves  47   a ,  47   b ,  47   c ,  47   d , and  47   e  of annular members  46   a ,  46   b ,  46   c ,  46   d , and  46   e . Illustratively, the sealing rings  52  each comprise a resilient o-ring which fluidly seals with an inner surface  53  of valve body  14  ( FIG. 2 ). More particularly, sealing rings  52   a  and  52   b  sealingly engage the first valve body portion  20 , and sealing rings  52   d  and  52   e  sealingly engage the second valve body portion  22 . Sealing ring  52   c  sealingly engages both first and second valve body portions  20  and  22 . As such, sealing ring  52   c  seals any gap between the first and second valve body portions  20  and  22 . Annular members  46   a ,  46   b ,  46   c ,  46   d ,  46   e  and sealing rings  52   a ,  52   b ,  52   c ,  52   d ,  52   e  cooperate to separate first fluid inlet  30 , second fluid inlet  34 , first fluid outlet  32 , and second fluid outlet  36 .  
      Second valve member or inner spool  18  is slidably mounted within first valve member  16 , as shown in  FIGS. 2 and 3 . Also as illustrated in  FIGS. 2, 3  and  5 , second valve member  18  includes a substantially cylindrical wall  54  including an outer surface  56  having an outer diameter d 2 . Illustratively, the difference between the outer diameter d 2  of second valve member  18  and the inner diameter d 1  of first valve member  16  is no more than 0.002 inches in order to facilitate fluid sealing therebetween. More particularly, the outer diameter d 2  is precision machined to be between a value equal to inner diameter d 1  and 0.002 inches less than inner diameter d 1 . Outer surface  56  further includes two axially spaced annular grooves  58   a ,  58   b . Grooves  58   a ,  58   b  provide selective fluid communication between first fluid inlet  30  and first fluid outlet  32 , and between second fluid inlet  34  and second fluid outlet  36  depending upon the axial position of second valve member  18 .  
      Cylindrical wall  54  further includes an inner surface  60  defining a first fluid conduit  62  and a second fluid conduit  64  separated by an internal wall or spacer  66 . A plurality of apertures  68   a  and  68   b  are formed within cylindrical wall  53  and communicate with grooves  58   a  and  58   b , respectively, to allow fluid flow from each inlet  30  and  34  to exert pressure against opposing sides  70  and  72  of the spacer  66 . In other words, pressure from a first fluid passing through first fluid inlet  30  exerts pressure against surface  70 , while pressure from a second fluid passing through second fluid inlet  34  exerts pressure against surface  72  in opposition to the first fluid pressure. In this way, the pressure within each outlet  32  and  36  is substantially equalized in the movement of second valve member  18 . Illustratively, apertures  68  include radially outwardly extending walls  73  and are axially elongated to provide an increased range of fluid flow.  
      In one illustrative embodiment, a plurality of ribs  74  are supported by opposing ends of second valve member  18 . Ribs  74  provide support for the outer diameter of the second valve member  18  during the precision machining process detailed below.  
      First and second valve members  16  and  18  are illustratively formed of an injection molded thermoplastic. In an alternate embodiment, the second valve member  18  may be formed of a metal, such as stainless steel. Examples of thermoplastics for valve members  16  and  18  include: polyphenylene sulfide (PPS): especially Fortron 6165 PPS which is commercially available from Ticona Manufacturing of Wilmington, N.C.; modified polyphenylene (m-PPE), such as Xyron G703H m-PPE which is commercially available from Asahi Kasei Corporation of Fowlerville, Mich.; polyvinyl chloride (PVC), such as Fiberloc 81510 which is commercially available from PolyOne Corporation of Avon Lake, Ohio; and polysulfone (PSU), such as Udel GF-120 PSU which is commercially available from Solvay Plumbing of Alpharetta, Ga. It should be appreciated, however, that this list is for illustrative purposes only and that the present invention is not limited to these particular materials.  
       FIG. 6  is a flow chart showing an illustrative method of manufacturing the pressure balance proportioning valve  12 . The process begins at step  100  by injection molding the first valve member  16 . This step includes providing a mold (not shown), injecting heated thermoplastic into a cavity of the mold, ejecting the molded first valve member from the mold, and cooling the first valve member. At step  102 , the second valve member  18  is injection molded in a manner similar to the first valve member  16  within a single mold, illustratively a multiple valve member mold. Injection molding of the second valve member  18  may occur simultaneously with injection molding of the first valve member  16 . Alternatively, the injection molding of valve members  16  and  18  may occur in separate molds.  
      The process continues at step  104  where the inner surface  40  of the first valve member  16  is precision machined, illustratively through a conventional cutting operation. More particularly, the inner surface  40  of the first valve member  16  is machined to predetermined inner diameter d 1 . Similarly, at step  106  the outer surface  56  of second valve member  18  is precision machined to predetermined outer diameter d 2 . More particularly, valve members  16  and  18  are machined such that outer diameter d 2  is no more than approximately 0.002 less than the inner diameter d 1 . Again, steps  104  and  106  may be accomplished simultaneously. The process continues to step  108  where the first and second valve members  16  and  18  are assembled by sliding the second valve member  18  within the passage  42  of the first valve member  16 . The reception of the second valve member  18  within the first valve member  16  creates a pressure balance proportioning valve or subassembly  12 . At step  110 , the subassembly  12  is positioned within the valve body  14 . As detailed above, the valve body  14  comprises two portions  20  and  22  coupled together and defining an internal chamber  24  within which the first valve member  16  of the subassembly  12  is non-rotatably disposed.  
      Although the invention has been described in detail with reference to certain preferred embodiments, variations and modifications exist within the spirit and scope of the invention as described and defined in the following claims.