Lubricated water valve
This is a continuation of co-pending application Ser. No. 634,761 filed on July 26, 1984 now abandoned. 
    
    
     FIELD OF THE INVENTION 
     My present invention relates to a water valve of the type having a stationary outer member, namely a valve housing or a sleeve inserted in such a housing, which has a cylindrical bore provided with one or two lateral inlet ports (e.g. for cold and hot water) and a lateral outlet port axially offset therefrom. A piston axially displaceable in the cylindrical bore is formed with an internal channel, closed at its ends, and with peripheral apertures enabling that internal channel to communicate with the inlet and outlet ports in one axial position to establish a flow path therebetween. In other axial positions, the piston apertures are partly or fully disaligned from at least one of the ports to throttle or cut off the flow between them. With two inlet ports as noted above, rotation of the piston in its flow-establishing axial position enables cold or hot water alone, or a selected mixture thereof, to reach the outlet port for discharge into a faucet or the like. The ports and the intervening flow path are fluidically separated from the extremities of the bore by suitable sealing means. 
     BACKGROUND OF THE INVENTION 
     A single-handle mixing valve of the type just referred to is the subject matter of U.S. Pat. No. 4,187,880 in the names of Jurgen Humpert et al. In such a valve, as well as in simpler valves with only one inlet port, it is frequently found that the displacement of the piston in surrounding outer member becomes increasingly more difficult with the passage of time. This appears to be due to diminishing lubrication as grease initially provided at the contact surfaces of the piston and the bore wall is washed out by water leakage. To remedy this problem, it has already been proposed (see U.S. Pat. No. 3,372,904 in the names of Bernard A. Graham et al) to provide the interior of the piston with a grease chamber from which lubricant can be pumped by means of a screw designed to displace a piston head in that chamber upon being rotated with the aid of an external tool such as an Allen wrench. Such a system is somewhat unhandy and calls for operation by an expert whenever relubrication is desired. 
     OBJECT OF THE INVENTION 
     The object of my present invention is to provide an improved water valve, preferably one of the single-handle mixing type, in which such relubrication occurs automatically without the need for intervention by an operator. 
     SUMMARY OF THE INVENTION 
     I realize this object, in accordance with my present invention, by providing the inner surface of the outer member at its extremities with inwardly open peripheral recesses storing grease which is entrainable by the piston, during axial reciprocation thereof, past the sealing means for lubricating adjacent areas of contact between the piston and the outer member. 
     Advantageously, pursuant to a more particular feature of my invention, the recesses are coaxial cylindrical enlargements of the piston-receiving bore so that even a slight tilting of a piston during manipulation thereof will cause grease to be entrained by it toward the contact regions. I have found on the basis of tests that an optimum depth of the grease chambers is given when the diameter of the enlargements equals substantially 1.1 times the diameter of the remainder of the bore. 
     In accordance with another advantageous feature of my invention, the recesses have radially inwardly tapering bottoms at boundary zones remote from the ends of the bore so as to converge toward the piston in these zones. Such a configuration facilitates the entrainment of part of the contents of these chambers toward the aforementioned contact surfaces past the intervening sealing means. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     The above and other features of my invention will now be described in detail with reference to the accompanying drawing the sole FIGURE of which is a longitudinal axial sectional view of a mixing valve incorporating the present improvemnt. 
    
    
     SPECIFIC DESCRIPTION 
     The water valve shown in the drawing has a structure essentially corresponding to that shown in the above-identified patent to Humpert et al which can be referred to for details. It is therefore sufficient to describe the principal constituents of the valve along with the modifications applied thereto in accordance with my present invention. 
     The valve comprises, essentially, a housing 1 forming a well 14 in which a cylindrical sleeve 2 fixedly received. Sleeve 2 has a bore 15 centered on a vertical axis, accommodating a piston 3 which is rotatable and axially slidable therein with the aid of a nonillustrated handle attached to a coupling head 16. Housing 1 forms a cold-water inlet port 11 and a hot-water inlet port 12 aligned with respective openings 17 and 18 of sleeve 2 which, in the illustrated rotary position of piston 3 shown to be located at its lowest level, communicate by way of peripheral aperatures 31 of the sleeve with an internal channel 4 thereof closed at its upper and lower ends. By way of several peripheral cutouts 32, channel 4 communicates in all piston positions with well 14 and thus with an outlet port 13 of housing 1. 
     As disclosed in the Humpert et al patent, apertures 31 are provided only on a part of the circumference of sleeve 2 which has an imperforate portion enabling either inlet port 11, 12 to be partly or completely blocked whereby a selected ratio of hot to cold water can be established in the flow (see arrows) passing to outlet port 13. The overall flow rate can be reduced, or the flow can be fully cut off, by elevating the piston 3 above its illustrated level. The flow path is fluidically isolated from the lower extremity of bore 15 by sealing rings 6a, 6b, encircling openings 17 and 18, and from its upper extremity by a peripheral sealing ring 5&#39;; a similar ring 5&#34; lies just below sealing rings 6a, 6b. Beyond sealing rings 5&#39; and 5&#34;, the extremities of bore 15 are radially enlarged to form an upper grease chamber 21&#39; and a lower grease chamber 21&#34; open toward the end faces of sleeve 2; at boundary zones 22&#39;, 22&#34; remote from these end faces, the depth of the grease chambers porgressively decreases so that their bottoms converge toward the sleeve 2. Thus, even a slight eccentricity of sleeve 2--virtually unavoidable during its manipulation--will let a peripheral area thereof pick up some of the grease present in one or both chambers 21&#39;, 21&#34; for entrainment past the seals 5&#39;, 5&#34; and 6a, 6b to ensure continued lubrication. Extraction of the sleeve 2 enables the grease chambers to be refilled. 
     It will be apparent that sleeve 2 could be omitted, with grease chambers 21&#39; and 21&#34; machined directly into the peripheral wall of well 14. In that case, however, though the mode of operation would be practically unaltered, the machining of the lower chamber 21&#34; at the bottom of the well would be more difficult.