Abstract:
A water mixing valve ( 10 ) can selectively adjust temperature by selection mixing of the hot and cold water supplies and be selectively locked in place by a knob ( 26 ) fastened via a threaded faster ( 30 ). The knob ( 26 ) has a spline section ( 34 ) seated in a complementary spline section ( 36 ) in the valve body ( 20 ) to prevent the knob ( 26 ) and operating stem ( 22 ) from inadvertent rotation.

Description:
TECHNICAL FIELD 
     The field of this invention relates to a temperature mixing valve for mixing hot and cold water supplies and more particularly to a lock stop for locking the set mix of water. 
     BACKGROUND OF THE DISCLOSURE 
     Many mixing valves have a control stem mounted to an operable handle that controls the mix of hot and cold water to the outlet port in a faucet. Often the control stem that controls the temperature mix is separate from the flow rate control portion of the faucet. As such, the temperature-mixing device can be located significantly upstream and removed from the flow rate control valve and the spout or final outlet port. Remote mixing valves are often used in conjunction with a bank of electronic faucets which turn on and off by sensing the presence of a persons hands or body. The electronic sensing device controls the on-off position and the flow rate of the valve but often does not control the mix of the hot and cold water. The hot and cold water supplies are premixed to a desired temperature upstream. 
     As such, the temperature-mixing valve is often concealed to prevent the casual user or unauthorized person from tampering with or inadvertently changing the temperature mix. While many of these mixing valves may be behind closed doors and remote from the faucet, they still have freely accessible handles, which may be easily and inadvertently changed. 
     What is needed is a temperature-mixing valve with a knob that can be easily locked in place to prevent casual tampering or inadvertent adjustment but can be readily released with a special tool to provide adjustment to the desired temperature. 
     SUMMARY OF THE DISCLOSURE 
     In accordance with one aspect of the invention, a rotatable handle assembly for a mixing valve includes a first stem member operably connected to a mixing valve element. The stem member is rotatably mounted onto a mixing valve body for operating the mixing valve element to adjust the mixed hot and cold water supplies. The stem extends outside of the valve body. A manually operable knob is mounted onto the stem and is rotationally affixed with the stem. The knob is axially movable between a first lock down position and an operable adjusting position. The knob has a splined section fitted with a complementary splined section of the valve body when in the lock down position to prevent the stem from rotation with respect to the valve body. A releasable fastener affixed the knob to the stem in the first lock down position Preferably, the spline section of the valve body is a formed female socket section surrounding the stem and the spline section of the knob is at a proximate axial end of the knob. At least one of the spline sections of the knob and valve body are chamfered to provide automatic meshing of the two spline sections as the knob is axially moved to the lock down position. 
     The fastener can be loosened to allow the knob to axially slide on the stem to the adjustable position. When in the adjustable position, the splined section of the knob is disengaged from the splined section of the valve body to allow the knob and stem to rotate to a desired mix position. 
     A spring element is preferably interposed between the knob and the valve body to bias the knob to the adjustable position. The fastener, when tightened, moves the knob against the bias of the spring to the lock down position. Preferably the fastener is fastened through a distal axial ends of the knob and the stem. 
     It is desirable that the fastener is a threaded fastener with a head having an allen wrench receptacle and is recess mounted in the distal end of the knob. It is also desirable that the knob has a narrow contour to deter casual or inadvertent manipulation but has external ribs for promoting manual grasping of the handle for ease of deliberate rotation. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Reference now is made to the accompanying drawings in which: 
     FIG. 1 is a perspective and exploded view of a mixing valve incorporating a lock stop handle assembly in accordance with one embodiment of the invention; 
     FIG. 2 is cross-sectional fragmentary view of the handle assembly taken along lines  2 — 2  shown in FIG. 1 with the handle assembly in the lock down position; 
     FIG. 3 is a view similar to FIG. 2 with the handle assembly shown in the adjustable position; 
     FIG. 4 is a cross sectional view taken along lines  4 — 4  shown in FIG. 2; 
     FIG. 5 is a cross-sectional view of the control knob illustrating the knob mounted onto the stem taken along lines  5 — 5  shown in FIG.  3 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to FIG. 1, a commercially available temperature mixing valve  10  has a cold water inlet  12 , hot water inlet  14 , and mixed water outlet  16  in a base fixture  18 . A conventional pressure balance proportioning valve and mixing valve element (not shown) are operably housed within the mixing valve body  20  that is secured to the base fixture  18 . The body  20  has a rotatable valve stem  22  extending therefrom. The valve stem  22  is operably connected to the mixing valve element and is rotatable to adjust the mix of cold and hot water from the inlets  12  and  14  to outlet  16 . 
     The stem  22  has two flats  24  such that the stem  22  can be non-rotatably connected to a knob  26  through its complementary shaped central aperture  25 , as illustrated in FIG.  5 . The knob is spring biased by a spring  28  away from the valve body  20 . A threaded fastener  30  affixes the knob to the stem through the distal ends  32  and  34  of the respective stem and knob. 
     Referring now to FIG. 2, when the fastener  30  is fully tightened, the knob  26  is pushed against the spring bias of spring  28 . The knob has its proximate spline section  36  seated in a spline section  38  of the valve body in socket  40  surrounding the stem  22 . Both spline sections  36  and  38  are fully circular and fully surround stem  22 . The respective spline sections  36  and  38  when engaged to each other prevent the knob  26  and the stem  22  from any rotation, as illustrated in FIG.  4 . As such the position of the stem  22  is fixed and not adjustable. As such, this lock down position of the fastener  30  and knob  25  prevent casual tampering with the stem  22  and inadvertent adjustment of the mixed water proportions set by the mixing valve  10 . 
     To further deny the casual tampering with the position of the mixing valve stem, the fastener  30 , when fully tightened, has its head  42  recessed within the distal end  34  of the knob. The head  42  further has an allen wrench type recess  44  therein. As such, the fastener is inaccessible to the casual user unless an allen wrench is used. 
     However, initial setting and later adjustment of the mixing valve temperature is readily possible. The threaded fastener can be loosened with the appropriate allen wrench. As the fastener is loosened, it moves on its threads and allows the knob  26  to move to the adjustable position shown in FIG.  3 . In this position, the spline sections  36  and  38  are disengaged and the knob is free to rotate with the stem  22  to adjust the temperature mix of the water. 
     The knob  26  has a narrow profile about stem  22  to deter casual or in advertent grasping thereof and to give a visual indication that the knob  26  is not the kind that is freely or commonly adjustable. However, the knob  26  has handle-facilitating ribs  50  on its outer side to promote deliberate manual rotation thereof. The knob  26  if desired can have a textured outer surface or have laterally extending external levers, or other embossments to further facilitate manual turning. 
     When the appropriate setting or adjustment is made, the fastener  30  is re-tightened and the spline sections  36  and  38  are reseated with each other. Each spline section has a chamfered or canted end  46  and  48  to provide automatic seating of the two spline sections  36  and  38  as the knob  26  is seated into the socket section  40 . The spline  36  and  38  are narrow enough to provide for seating about multiple positions such as 20 different positions so that the temperature adjustment increments are relatively small i.e. increments as small as 2° F. 
     In this fashion, the temperature-mixing valve allows for adjustment of the water temperature by an authorized or deliberate action but deters inadvertent adjustments or casual tampering of the temperature mix. 
     Variations and modifications are possible without departing from the scope and spirit of the present invention as defined by the appended claims.