Abstract:
A diverter valve ( 10 ) for selectively controlling the flow of fluid from a fluid source to one of several fluid outlets ( 132, 136 ) includes a fixed ceramic disk ( 14 ) fixed to a housing ( 12 ) and a rotating ceramic disk ( 16 ) retained in the housing against the fixed disk by a retainer ( 24 ). An accessory mount ( 20 ) is adhered to the rotating ceramic disk to facilitate connection to accessories and to direct fluid from the valve. Flow passages ( 88, 90, 104, 106, 108, 110, 112 ) in the disks cooperate with flow passages ( 54, 64, 66, 68 ) in the housing and flow passages ( 116, 118, 122 ) in the accessory mount to balance the pressure of fluid flow within the valve against the disks to minimize leaks and prolong durability.

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
   This application claims priority on International Application No. PCT/US2004/033436, filed Oct. 8, 2004, which claims the benefit of U.S. Provisional Patent Application 60/481,890, filed Oct. 10, 2003, both are incorporated herein in their entirety. 

   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The invention relates to a diverter valve that selectively diverts water from a conventional kitchen faucet to one of two or more outlets, and more particularly, to a diverter valve having ceramic disk elements. 
   2. Description of the Related Art 
   Fluid valves using ceramic valve stacks comprising a fixed ceramic disk and a rotating ceramic disk, both of which have pass-through openings to control the flow of fluid through the valve by selective movement of the rotatable ceramic disk, are well known. They typically appear in various configurations, such as in-line valves, conventional faucets, diverter valves, and hydrants, to name a few. Almost all ceramic valves comprise a “stack-up” that traditionally includes a seal, a fixed ceramic disk, a rotating ceramic disk, and a bearing in contact with the rotating ceramic disk. The stack-up is typically contained within a valve body, which defines the various inlets and outlets to the fluid sources. 
   For such a valve to work properly, the fixed and rotating ceramic disks must be held together in compression with force (the stack-up pressure) sufficient to prevent fluid from leaking between the interface of the disks. At the same time, the torque required to rotate the rotatable ceramic disk must be within a predetermined value, so that a user can easily use the device. The torque is the force that a user must supply to the handle of the valve (or to the valve itself) to rotate the rotating disk with respect to the fixed disk to turn the valve through its various operating positions. Although there is some subjectivity in the predetermined torque value, the force must always remain low enough to permit the weakest of users to easily operate the valve. 
   Commonly assigned U.S. Pat. No. RE35,545 discloses mounting a retainer to a positive stop in order to obtain a repeatable stack up pressure. Commonly assigned U.S. Pat. Nos. 6,405,756 and 6,575,196 disclose a means of reducing the stack up pressure. Normally, balancing the stack up pressure and torque is not a problem with these solutions, but in a valve with complex flows through the disks, e.g. a diverter valve, it has been found that uneven hydraulic pressures on the disks tend to cause leaks. Moreover, risk of leaks and higher costs attend existing diverter valves where flow must be directed from the rotatable ceramic through a lower housing. 
   Thus, there is a need for a ceramic diverter valve that balances hydraulic pressures within the ceramic disks, maintains a sufficiently low operating torque, and more reliably directs flow through the rotatable disk to the outlets. 
   SUMMARY OF THE INVENTION 
   The invention lies in a diverter valve for selectively controlling the flow of fluid from a fluid source to one of at least two fluid outlets. The valve comprises a housing defining at least one flow passage. A first ceramic plate mounts to the housing, fixed against rotation, and has at least one flow passage in registry with the housing flow passage. A second ceramic plate rotatably mounts within the housing, and has at least one flow passage that can be selectively placed into fluid communication with the housing flow passage. The diverter valve further has an accessory case adhered to the second ceramic plate. The accessory case has at least one flow passage in registry with the second ceramic plate flow passage. The flow passage in the accessory case is configured to mount a flow adapter. 
   Preferably, the accessory case is adhered to the second ceramic plate by an adhesive. Ideally, the adhesive is epoxy. Also, preferably, the accessory case mounts two flow adapters. One flow adapter is for aerated flow and a second flow adapter is for stream flow. In another aspect, the first ceramic plate is adhered to the housing. 
   In another aspect of the invention, the diverter valve has the flow passages in the housing and the accessory case configured and oriented to substantially balance hydraulic pressures acting on the ceramic plates. In one embodiment, a flow passage in the housing is open to and parallel with the first ceramic plate whereby pressure in the flow passage can act against the first ceramic plate to urge it toward the second ceramic plate. 
   In a further aspect of the invention, the diverter valve includes a thrust bearing and a retainer. The thrust bearing is disposed between the retainer and the second ceramic plate, and bears against the second ceramic plate with reduced friction to enable the second ceramic plate to rotate with lower torque. In one embodiment, the thrust bearing includes a wave spring and washer. In another embodiment, the thrust bearing is a low friction washer. Preferably the low friction washer comprises PTFE. And in a third embodiment, the thrust bearing is a roller bearing. 
   In another aspect, the first ceramic plate is adhered to the housing. And, the diverter valve has at least one ring seal between the first ceramic plate and the housing. Preferably it has three ring seals between the first ceramic plate and the housing. The ring seal can be seated within a groove. And, preferably, the groove is a dovetail groove. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the drawings: 
       FIG. 1  is an exploded view of a diverter valve in accordance with the invention. 
       FIG. 2  is a bottom view of the housing of the diverter valve of  FIG. 1 . 
       FIG. 3  is a top view of the fixed disk of the diverter valve of  FIG. 1 . 
       FIG. 4  is a bottom view of the fixed disk. 
       FIG. 5  is a top view of the rotating disk of the diverter valve of  FIG. 1 . 
       FIG. 6  is a bottom view of the rotating disk. 
       FIG. 7  is a top view of the accessory mount of the diverter valve of  FIG. 1 . 
       FIG. 8  is a bottom view of the accessory mount. 
       FIG. 9  is an enlarged view of the selection ring. 
       FIG. 10  is a side view of the diverter valve of  FIG. 1 . 
       FIG. 11  is a cross sectional view of the diverter valve of  FIG. 10  taken along line  11 - 11 . 
       FIG. 12  is a plan view of several components of the diverter valve of  FIG. 1  in a first position where water entering the valve is diverted to a filter and returned to the valve where it exits the accessory mount. 
       FIG. 13  illustrates the water flow path through the valve in the first position. 
       FIG. 14  is a plan view of several components of the diverter valve of  FIG. 1  in a second position where water entering the valve is diverted to a spray outlet as it exits the accessory mount. 
       FIG. 15  illustrates the water flow path through the valve in the second position. 
       FIG. 16  is a plan view of several components of the diverter valve of  FIG. 1  in a third position where water entering the valve is diverted to an aerator as it exits the accessory mount. 
       FIG. 17  illustrates the water flow path through the valve in the third position. 
       FIG. 18  is a cross sectional view, similar to  FIG. 11 , of a second embodiment of the diverter valve according to the invention. 
       FIG. 19  is a bottom view, similar to  FIG. 2 , of the housing of the second embodiment of the diverter valve. 
       FIG. 20  is cross sectional view taken along line  19 - 19  of  FIG. 18  with an O-ring installed. 
       FIG. 21  is a cross sectional view, similar to  FIGS. 11 and 18 , of a third embodiment of a diverter valve according to the invention. 
       FIG. 22  is an exploded isometric view of the thrust bearing of  FIG. 21 . 
       FIG. 23  is a cross sectional view of the thrust bearing of  FIG. 22 , taken along line  23 - 23 . 
   

   DETAILED DESCRIPTION 
     FIG. 1  illustrates a valve  10  according to the invention. The valve  10  comprises basically a housing  12 , a fixed ceramic plate or disk  14 , and a rotating ceramic plate or disk  16 , the rotation of which is controlled by a selection ring  18 , an accessory mount  20 , a detent case  22 , and a retainer  24 . As will be described in further detail later, the fixed ceramic disk  14  is fixed to the housing  12  against rotational movement, and the accessory mount  20  is adhered to the rotating ceramic disk  16 . For convenience, the rotating ceramic disk/accessory mount assembly will sometimes be referred to as an outlet assembly  26 . The retainer  24  retains the outlet assembly  26 , the detent case  22 , and the selection ring  18  in the housing  12 . A wave spring  28  and a washer  30  facilitate sealing the valve and constitute a thrust bearing that maintains the rotating ceramic disk  16  against the fixed ceramic disk  14  while minimizing torque when the rotating ceramic disk  16  is rotated. It will be appreciated that this embodiment of a bearing is most suitable for uses where low fluid pressures will exist within the valve, typically below about 80 psi. Performance may degrade at higher pressures 
   Referring now to  FIGS. 1 ,  2 , and  11 , the housing  12  can be formed of metal, such as brass, or a suitable polymer, such as Polyoxymethylene, and has a roughly cylindrical shape with a longitudinal axis  32 . An upper body portion  34  and a lower body portion  36  are aligned on the axis  32 . A collar  38  projects from the upper body portion  34  and is also preferably aligned on the axis  32 . The lower body portion  36  comprises a pair of oppositely disposed partial cylindrical walls  40  that define a cavity  42  that is open through a lower end  44  of the housing  12  and also through the axial edges  46  of the partial cylindrical walls  40 . A stepped recess  48  in the cavity  42  is bounded by an annular wall  50  and a face  52  in the upper body portion  34 . The stepped recess  48  forms a seat for the fixed disk  14 . The outside of each partial cylindrical wall  40  adjacent the lower end  44  is threaded. 
   An inlet conduit  54  extends preferably along the axis  32  from the collar  38  through the face  52  and is adapted to fluidly connect to a source of water, such as from a faucet. The inlet conduit  54  has a flare portion  56  at the face  52 . A filter inlet  60  and a filter outlet  62  comprise stepped openings parallel to each other on opposite sides of and not connected to the inlet conduit  54 . The filter inlet  60  and a filter outlet  62  extend through a side of the upper body portion  34  and are sized and configured to accept standard fittings, such as John Guest® fittings, that will facilitate connection to a water filtration unit. The inner end  64  of the filter inlet  60  connects to a depending conduit  66  that terminates at a channel  68  in the face  52 . Similarly, the inner end  70  of the filter outlet  62  connects to a depending conduit  72  that terminates at a channel  74  in the face  52 . The channels  68 ,  74  are not parallel and extend from the conduits  66 ,  72  toward termination points  76 ,  78 , respectively, that are somewhat closer to the longitudinal axis  32 . 
   Referring now to  FIGS. 1 ,  3 , and  4 , the fixed ceramic disk  14  is generally circular and has on one side an adhering face  80  and on the other side, a bearing face  82 . Four pass through openings  84 ,  86 ,  88 , and  90  extend through the disk  14  from the adhering face  80  to the bearing face  82 . The disk  14  is sized to nest within the stepped recess  48 , with the adhering face  80  adhered to the face  52  of the upper body portion  34 . In one embodiment, the disk  14  is adhered to the face  52  using any suitable adhesive that will fix the disk to the upper body portion  34  permanently, and within a maximum temperature range to be found in the application to which the valve  10  is to be used. An example is an epoxy. It will be appreciated that this first embodiment, where the fixed ceramic disk  14  is adhered to the face  52  of the upper body portion  34 , is preferable for uses where low fluid pressures will exist within the valve, typically below about 80 psi. Performance may degrade at higher pressures. 
   The opening  84  is positioned to be in registry with the termination point  78 , and the opening  86  is positioned to be in registry with the termination point  76 . Openings  88 ,  90  are positioned preferably along a diameter of the disk  14  to be within the flare portion  56  of the inlet conduit  54 . Slots  92 ,  94  extend along the diameter of the disk  14  from the respective openings  88 ,  90  at the bearing face  82 . The bearing face  82  comprises a smaller irregular contact surface  96  that might be formed by removing material from the bearing surface along its peripheral edges. The smaller contact surface  96  helps to reduce torque. As is conventional in ceramic disk valves, the contact surface  96  must be polished flat. 
   Referring now to  FIGS. 1 ,  5 , and  6 , the rotating ceramic disk  16  has a generally circular shape from which extend keys  98 . The rotating ceramic disk  16  has a larger diameter than the fixed ceramic disk  14  and includes a bearing face  100  on one side and an outlet face  102  on the other side. The bearing face  100  has a smaller diameter contact surface  103  that is polished flat and is of a size no smaller than the contact surface  96  of the fixed disk  14 . The rotating ceramic disk  16  has four pass through openings and a blind slot in the contact surface  103 . Two center openings  104 ,  106  are disposed on a diameter of the disk  16  and are spaced from each other to be in registry with the openings  88 ,  90  in a first position of the rotating disk  16  relative to the fixed disk  14 . A spray opening  108  is positioned to be in registry with one of the slots  92 ,  94  in the fixed disk  14  in a second position of the rotating disk  16  relative to the fixed disk  14 , when simultaneously, the two center openings  104 ,  106  will not be in registry with the openings  88 ,  90 . An elongated filter opening  110  is positioned near the perimeter  111  of the contact surface  103  to be in registry with opening  86  in the fixed disk  14  in a third position of the rotating disk  16  relative to the fixed disk  14 . An elongated blind slot  112  is sized and positioned within the contact surface  103  to place the opening  84  into fluid communication with the slot  92  (both on the fixed disk  14 ) at the same time that the elongated filter opening  110  is in registry with the opening  86 . 
   Looking now at  FIGS. 1 ,  7  and  8 , the accessory mount  20  is a disk preferably formed of metal, such as brass, or a suitable polymer, such as Polyoxymethylene, and has an adhering surface  113  and an opposite outlet surface  114 . The accessory mount  20  need not be formed of the same material as the housing  12 , although for economic or aesthetic reasons, it may be preferable to do so. The adhering surface  113  is adapted to be fixed to the outlet face  102  of the rotating ceramic disk  16 . Preferably the accessory mount  20  is adhered to the outlet face  102  using any suitable adhesive that will fix the adhering surface  112  to the outlet face  102  permanently, and within a maximum temperature range to be found in the application to which the valve  10  is to be used. An example is an epoxy. 
   The accessory mount  20  has a center aperture  116  that is sized to encompass the two center openings  104 ,  106  in the rotating ceramic disk  16 . An annular groove  118 , spaced outwardly from the center aperture  116  is positioned to fluidly communicate with the spray opening  108 . A plurality of spray openings  120  extends from the groove  118  to the outlet surface  114 , surrounding the center aperture  116 . An annular blind slot  122  extends through an arc of less than 90° from a first end  124  to a second end  126 . At the second end  126 , a filter outlet opening  128  extends through the accessory mount  20  to the outlet surface  114 . At the outlet surface  114 , the center aperture  116  has an internally threaded bore  130  adapted to receive a conventional aerator  132 . Similarly, the filter outlet opening  128  has an internally threaded bore  134  adapted to receive a laminator  136 . 
   The accessory mount  20  also has two bores  138 ,  140  extending inwardly along a diameter. The bores  138 ,  140  are adapted to receive springs and balls (not shown) for the purpose of interacting with the detent case  22 . As can be seen in  FIG. 1 , the detent case  22  is a ring that has a pair of outwardly extending flanges  142 , sized and spaced to fit closely between the partial cylindrical walls  40 . The internal diameter of the detent case  22  is nominally larger than the diameter of the accessory mount  20 ; enough to enable the accessory mount to rotate freely within the detent case. A number of detents  144  are provided in an interior wall of the detent case, each detent corresponding to one of the first, second or third positions of the rotating ceramic disk  16  relative to the fixed ceramic disk  14 . Typically, the detent case will be made of self-lubricated material such as Delrin®. 
   Looking now at  FIGS. 1 and 9 , the selection ring  18  comprises an outer collar  146  and an inwardly directed annular lip  148  in which are formed diametrically opposing key holes  150 , sized to receive the keys  98  of the rotating ceramic disk  16  when the valve  10  is assembled. The diameter of the selection ring  18  is nominally larger than the outside diameter of the partial cylindrical walls  40 ; enough to enable the selection ring  18  to rotate freely around the partial cylindrical walls  40 . The outer collar  146  has a knurled portion  152  and an indicia portion  154 . The knurled portion  152  enables a user to grasp the selection ring  18  and manually rotate the rotatable ceramic disk  16  to one of the predetermined first, second and third positions. Visible indicia  156  on the indicia portion  154  correspond to each of the first, second and third positions so a user can easily determine where and in which direction to rotate the selection ring to obtain a particular one of the first, second and third positions. 
   Referring to  FIGS. 1 ,  10  and  11 , the assembly of the valve  10  will be described in detail. Initially, it should be noted that the particular sequence of the assembly as described here is only one of the many possible combinations for assembling the valve. Many of the various ways to assemble the valve are equally preferred. Therefore, the described assembly of the valve is only meant to better describe the interfitting of the various valve elements and is not meant to limit the valve assembly to the described sequence. 
   The outlet assembly  26  is positioned within the cavity  42  so that the contact surface of the rotating ceramic disk bears against the contact surface of the fixed ceramic disk, with the keys extending between the partial cylindrical walls  40 . It will be apparent that the outlet assembly  26  is thus rotatable relative to the fixed ceramic disk  14  within a range limited by the keys&#39; freedom of movement between the axial edges  46  that effectively function as stops. The selector ring  18  is disposed over the partial cylindrical walls  40  until the key holes  150  receive the keys  98 . The wave spring  28  is then placed over the accessory mount  20  to bear against the rotating ceramic disk  16 . The washer  30 , preferably Polyoxymethylene, is then placed over the accessory mount  20  to bear against the wave spring  28 . Lubricity is important in order to minimize torque on the rotating disk  14 , so it will be appreciated that the wave spring  28  provides finite contact points at the rotating disk and the washer where friction occurs. 
   The detent case  22  is then positioned over the accessory mount  20  to bear against the washer  30  with the extending flanges  142  disposed between the partial cylindrical walls  40 , thus fixing the detent case relative to the housing  12 . Finally, the retainer  24  is threaded onto the external threads of the partial cylindrical walls  40 . The retainer  24  has an internally directed flange  158  that bears against the detent case  22 , which, in turn places pressure on the washer  31 , wave spring  28  and the rotating ceramic disk  16  against the fixed ceramic disk  14  to establish the stack up pressure. Preferably, the retainer (or the housing) has a stop that will positively position the retainer on the housing at a predetermined position as described and claimed in U.S. Pat. No. RE35,545. Outlet adapters, such as the aforementioned aerator  132  and laminator  136  can be attached to the accessory mount  20  as desired. It will be understood that the axis of rotation of the outlet assembly  26  is the longitudinal axis  32 . 
   To use the valve  10 , an adapter  160  can be mounted to the collar  38 . The adapter  160  enables the valve  10  to be mounted to a conventional faucet, such as a kitchen faucet, so that water coming from the kitchen faucet will enter the inlet conduit  54 . Also, the filter inlet  60  and filter outlet  62  will connect to a water filtration unit, preferably using conventional John Guest® fittings. With this assembly, the valve  10  is secured to the faucet so it will not rotate, yet the torque required to rotate the selection ring  18  is low enough so that the user can easily rotate it, and also nowhere near enough to cause the valve to rotate relative to the faucet. Preferably, the torque is 5 inch-lbs. or less. 
   Operation of the valve  10  will be described with respect to  FIGS. 12-17 .  FIGS. 12 and 13  illustrate the relative positions of the housing face  52 , fixed ceramic disk  14 , rotating ceramic disk  16 , and accessory mount  20  when the outlet assembly  26  is in the first position, including the fluid flow path through the valve  10 . In this position, water flows from the faucet to the filtration unit (not shown), returns from the filtration unit, and is directed to the filter outlet opening  128 . For illustrative purposes,  FIG. 11  shows some of the components in phantom with a view looking down through the valve  10 . 
   In the first position, water enters the inlet conduit  54  from the faucet where it passes through the flare portion  56  and into the pass through openings  88 ,  90  of the fixed disk  14 . Opening  88  is blocked by the contact surface of the rotating ceramic disk  14 , but opening  90  is in fluid communication with the elongated blind slot  112  by way of the slot  94 . Consequently, water flows through the blind slot  112  to the opening  86 , which is in registry with the termination point  76 . Water continues to flow through channel  68  to conduit  66 , then to the filter inlet  60  and to the filtration unit (not shown). Water exiting the filtration unit enters the valve  10  through the filter outlet  62 , then into the depending conduit  72 , through channel  74  and to the termination point  78 . Here, water flows through the termination point  78  which is in registry with opening  84 , and which in turn by the position of the outlet assembly  26 , is in registry with the elongated filter opening  110  of the rotating ceramic disk  16 . Simultaneously, water passing through the elongated filter opening  110  enters the annular blind slot  122  of the accessory mount, there to exit the valve  10  through the filer outlet opening  128 . Preferably, the flow of filtered water is laminated through the laminator  136 . 
     FIGS. 14 and 15  illustrate the relative positions of the components in the second position. In the second position, water enters the inlet conduit  54  from the faucet where it passes through the flare portion  56  and into the pass through openings  88 ,  90  of the fixed disk  14 . Opening  90  is blocked by the contact surface of the rotating ceramic disk  14 , but opening  88  is in fluid communication with the spray opening  108  by way of the slot  92 . Simultaneously, water is blocked from entry into the filter inlet  60  of the housing  12  and from entry into the center openings  104 ,  106  of the rotating disk  16 . Water flow through the spray opening  108  and into the groove  118  in the accessory mount  20  where it exits in a spray through the spray openings  120 . 
     FIGS. 16 and 17  illustrate the relative positions of the components in the third position. In the third position, water enters the inlet conduit  54  from the faucet where it passes through the flare portion  56  and into the pass through openings  88 ,  90  of the fixed disk  14 . Since the pass through openings  88 ,  90  are in registry with the two center openings  104  and  106 , water passes through the rotating ceramic disk  16  and out through the center aperture  116  in the accessory mount  20 , which is also in registry with the center openings  104  and  106 . Preferably, this flow of unfiltered water is aerated through the aerator  132 . 
   Key elements of a second embodiment of a diverter valve according to the invention are shown in  FIGS. 18-20 . Looking first at  FIG. 18 , it can be seen that the second embodiment is in all respects identical to the first embodiment (where like parts bear like numerals) except that (1) the fixed disk  14 ′ is not adhered to the housing  12 ′, (2) grooves and sealing rings are disposed in the face  52 ′ of the upper body portion  34 ′, and (3) instead of the wave spring  28  and washer, the thrust bearing comprises a thrust washer  161 . The second embodiment is particularly appropriate where higher fluid input pressures exist, e.g. above about 80 psi. In such case, a wave spring would not normally be sufficient to keep the rotating disk fluidly tight against the fixed disk. 
   In this embodiment, the thrust washer  161  will preferably be formed of Teflon®-filled Delrin®, and sized to permit the retainer  24  to securely hold the rotating disk  16  against the fixed disk  14 ′. The thrust washer  161  should be friction reducing, and its composition can be adjusted accordingly. For example, a Delrin® thrust washer with PTFE will have a lower coefficient of friction than one without PTFE. The fixed disk  14 ′ is sealed against the face  52 ′ by sealing rings  162 ,  164 , and  166 . The size, shape and disposition of the sealing rings  162 ,  164 , and  166  are selected to minimize torque as the rotating disk  16  is rotated relative to the fixed disk  14 ′. For example, each sealing ring can be circular in cross section and 0.070 inches in diameter. Alternatively, one or more sealing rings can be oblong or obround and have a varying diameter, e.g., where the ends are circular in cross section and where the sides are higher than wide. 
   Looking now at  FIGS. 19 and 20 , the sealing rings  162 ,  164 , and  166  are disposed, respectively in grooves  168 ,  170 , and  172  in the face  52 ′ of the upper body portion  34 ′. The groove  168  is formed at the periphery of the flare portion  56 ; the groove  170  is formed at the periphery of the channel  74 ; and the groove  172  is formed at the periphery of the channel  66 . Preferably, at least a portion of each groove  162 ,  164 , and  166  is dovetailed (see  FIG. 20 ) to provide additional space for the sealing rings to deform when they are compressed by the fixed disk  14 ′ and by water pressure in the adjacent channel. For example, the groove along the sides of the channel might not be dovetailed but the groove at the ends of the channel may be dovetailed. In a preferred embodiment, the grooves  162 ,  164 , and  166  are countersunk approximately 0.050 inches. Also, a notch  174  is formed in the upper body portion  34 ′ to accommodate a tab (not shown) on the fixed disk  14 ′ so that the fixed disk can be properly aligned relative to the housing  12 ′ and fixed against rotation. 
   Operation of the second embodiment is otherwise identical to operation of the first embodiment. In this embodiment, however, the fixed disk  14 ′ has some limited freedom to move axially relative to the housing  12 ′. Thus, when hydraulic pressure in the housing passages  66 ,  68 ,  72 ,  74 , and/or  56  is elevated, e.g. on the order of 190 psi or so, the pressure tends to urge the fixed disk toward the rotating disk  16 , which in turn generates force on the thrust washer  161 . The sealing rings maintain a seal between the fixed disk  14 ′ and the housing face  52 ′, but it may also be advisable to provide a PTFE washer (not shown) between the thrust washer  161  and the detent case  22  in order to maintain sufficiently low torque. 
   Looking now at  FIGS. 21-23 , it can be seen that a third embodiment of the diverter valve  10  is in all respects identical to the second embodiment (where like parts bear like numerals), except that the thrust bearing  23 ′ is a roller bearing  176 . It is to be understood that the thrust bearing of the third embodiment can also be used equally effectively in the first embodiment. 
   The roller bearing  176  comprises two flat rings, an upper ring  178  and a lower ring  180 , disposed coaxially and spaced from each other to define a race  182  between them. The rings  178 ,  180  are preferably formed of steel, although any material having a hard, non-wearable surface will suffice. Within the race  182  is a self-lubricated ring  184 , preferably formed of Delrin®, having a plurality of apertures  186  spaced evenly about the ring, and having a thickness less than the thickness of the race. The walls of each aperture  186  are spherically arcuate with a radius centered in the middle of the aperture. A roller ball  188 , preferably formed of steel or other hard material, and having a radius slightly less than the radius of the aperture, is disposed in each aperture  186  and rotatable freely therein. There are at least 8 balls, and preferably 16. The upper ring  178  bears against the rotating ceramic disk  16 . The lower ring  180  bears against the detent case  22 . The balls  188  are held firmly within the race  182 , between the upper  178  and lower  180  rings, and maintained in special relationship to one another by the Delrin ring  184 . The Delrin ring  184 , having a thickness less than the race  182 , does not contact either the upper  178  or lower  180  ring. The thrust bearing, being part of the stack-up, is held with predetermined force between the detent case  22  and the rotating disk  16  by the retainer  24 . As the rotating disk  16  is rotated by actuation of the selection ring  18 , it causes the upper ring  178  to rotate with it. As it does, the balls  188  in the race  182  are urged to roll between the lower  180  and upper  178  rings with minimal resistance. Consequently, the torque required to move the rotating disk  16  is very low. 
   While the invention has been specifically described in connection with certain specific embodiments thereof, it is to be understood that this is by way of illustration and not of limitation, and the scope of the appended claims should be construed as broadly as the prior art will permit.