Anti-stall ball-check valve
BACKGROUND OF THE INVENTION 
     The present invention relates generally to a ball-check valve for a pump, and more particularly to a valve for use in the vertical piping of a sanitary diaphragm pump. 
     Diaphragm pumps are well known and are often used in the food industry where the sanitary condition of the pump and its valves are a prime consideration. A ball-check valve used in a sanitary pump requires inspection at frequent intervals of the valve seat, the ball, and other internal surfaces to check for entrapped food particles that can cause buildup of bacteria. The porosity of stainless steel and the surface roughness of welds are problems in such an application. 
     Known ball-check valves such as disclosed in the Hallstrom Jr. U.S. Pat. No. 2,934,024 dated Apr. 26, 1980, include a removable ball and valve seat, but is not readily inspected. Other valves, such as the Wilden Model M-8 &#34;Foodmaster&#34; pump, include a removable elastomer valve seat, an elastomer ball, and a ball valve cage. These features facilitate inspection and cleaning of the valve, but the valve seat, because of constant friction in use, requires frequent replacement. Moreover, the valve cage is larger in size, expensive to manufacture, reduces the size of particles which can pass through the valve, and increases the time necessary for inspection and cleaning. 
     Other known valves such as the Depa DL-40SL replace the removable valve seat with an integral seat and replace the valve cage with a solid bar ball stop welded into the valve housing from the outside, since welding is unacceptable for sanitary application on the inside because of the extreme difficulty to weld, grind and polish. However, this lack of unitary structure on the inside results in bacterial buildup. In addition, this design does not permit a visual inspection of the inside passages of the valve. 
     It is accordingly an object of the present invention to obviate the above described deficiencies and to provide a novel ball-check valve for use in a sanitary pump or other application. 
     It is another object of the present invention to provide a novel ball-check valve which is less expensive to produce, self-cleaning in design, and easily inspected. 
     It is still another object of the present invention to provide a novel ball-check valve structure with an integral housing and valve seat and easily removable ball stop. 
     It is yet another object of the present invention to provide a novel ball-check valve in which all internal surfaces may be visually inspected when looking inward from the outlet end of the valve. 
     It is a further object of the present invention to provide an anti-stall ball-check valve for a low pressure pump. 
     Yet a further object of the present invention is to provide a novel ball-check valve in which elastomer-to-elastomer contact is avoided. 
     Yet another object of the present invention is to provide a novel ball-check valve which does not require welding. 
     Yet a further object of the present invention is to provide a novel ball-check valve which has a valve seat unitary with the valve housing so that the difficulty in valve seat removal and bacterial build-up can be avoided. 
     These and many other objects and advantages will be readily apparent to one skilled in the art to which the invention pertains from a perusal of the claims and the following detailed description of the preferred embodiments when read in conjunction with the appended drawings. 
    
    
     THE DRAWINGS 
     FIG. 1 is an elevation of the valve of the present invention in cross-section showing a unitary valve housing with an integral valve seat, a ball resting on the seat with an alternative position shown in dashed lines, and a ball stop resting on an annular groove in the housing at the outlet end; 
     FIG. 2 is an elevation of an alternative embodiment of the valve of the present invention in cross-section illustrating a smaller inlet end to accommodate variations in the size of pump piping and the method of assembly; and 
     FIG. 3 is a top plan view of the ball stop of FIGS. 1 and 2. 
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     With reference to the figures where like elements have been given like numbers to facilitate an understanding of the present invention, and particularly with reference to the embodiment of the present invention illustrated in FIG. 1, a unitary valve housing 10 defines a generally cylindrical passageway with a constriction 12 intermediate the ends of the housing to form a valve seat 13. A ball 14 is seated on the valve seat and a removable ball stop 16, described in more detail below in connection with FIG. 3, rests within an annular groove 18 in the housing at the outlet end. 
     The constriction 12 is generally V-shaped, with the surface 20 on the outlet side forming an angle between about 30 degrees and about 45 degrees, preferably about 45 degrees, to the passageway. The slope 22 of the surface on the inlet side forms an angle of about 68 degrees to the passageway. 
     The passageway and constriction 12 of the housing 10 are configured to permit inspection of all internal surfaces of the housing 10, both above and below the valve seat, when looking inward from the outlet end of the valve, i.e., the entire surface 22 is visible from the outlet end of the valve housing. 
     The valve housing 10 may be machined and finished using stainless alloy bar stock or tubing and the valve seat may be machined and finished as an integral part of the housing 10. The resulting unitary construction eliminates the need for a removable valve seat and the added expense and maintenance involved with a removable valve seat. 
     FIG. 2 discloses an alternative configuration of the housing 10 which has an inlet end that is smaller than the outlet end. 
     As shown in FIG. 2, the ball stop 16 may be removably positioned into the annular groove 18 in the outlet end of the housing 10, and may thus be easily removed to permit removal of the ball 14 and inspection and cleaning of the valve passageway. The ball stop 16 eliminates the need for a welded stop and associated problems of keeping such stop free of contamination. 
     As shown in FIG. 3, the ball stop 16 may have a circular ring 24 sized to rest in the groove 18 with a single bar 26 bisecting the ring 24 to retain the ball 14 within the housing 10. As shown in FIG. 1, a portion of the ball may pass between the bar 26 and the ring 24. 
     As shown in FIG. 1, the slope of the surface 20, the cross-sectional area of the passageway on the outlet side of the valve seat 13, the diameter of the ball 14, and the distance between the ball stop 16 and the valve seat 13 are such that the distance D-1 between the ball 14 and the housing 10 along the passageway between the ball stop 16 and the valve seat when the ball 14 is stopped by the ball stop 16 is not less than the minimum diameter of the passageway as defined by the constriction 12. The relative configurations of the passageway between the valve seat and the outlet end, the ball 14, and the removable ball stop 16 provide a means for channeling solids from the constriction 12 to the outlet end for discharge without stalling the valve, i.e., the jamming of the ball in the open position by a solid. 
     The ball 14 may be hollow and constructed of an elastomeric material to make it sufficiently light in weight to be effective for use in a low pressure typical in food pumps. 
     As shown in FIGS. 1 and 2, both the inlet and outlet ends preferably have an annular groove 28 for an O-ring 30 to be inserted when clamping the valve housing 10 to the vertical piping 32 of the pump by any suitable conventional means such as clamps 34. As shown in FIG. 2, the valve may be readily inspected by unclamping the outlet end of the valve from the piping 32, laterally displacing the piping 32 to provide access to the outlet end of the valve, removing the ball stop 16 and the ball 14, and visually inspecting all surfaces thereof for traces of entrapped solids. Unclamping the inlet end of the housing 10 is not critical to this method of inspection and can be performed on a valve, such as the one illustrated in FIG. 2, that is integral with the pipe or hose at the inlet end. 
     While the preferred embodiments of the present invention have been described, variations and modifications will naturally occur to those skilled in the art from a perusal hereof. It is therefore, to be understood that the embodiments described are illustrative only and that the scope of the invention is to be defined solely by the appended claims when accorded a full range of equivalence.