Abstract:
A means for adjusting the relative positioning of a valve closure element with respect to a valve seat is formed by a hub on the closure element having a valve stem receiving bore and at least two generally opposed threaded passages intersecting the bore. Threaded members are received in each bore to engage the valve stem from generally opposite sides thereof. Movement of the threaded members adjusts the relative positioning of the closure element with respect to the valve seat and valve stems while securing the closure element to the latter.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to fluid control valves and more particularly to a means and method for connecting the disk of a butterfly valve to the stems in such fashion as to allow for adjustability in positioning of the valve disk relative to the valve seat. 
     2. Description of the Prior Art 
     Valves employing pivotal closure elements, such as butterfly valves, are widely used in industry for fluid handling and control. In particular, butterfly valves employing resilient sealing means engaging rigid metal members are extensively used in a wide variety of environments since a good pressure tight seal can be obtained. This is at least in part due to the deflection or resiliency of the sealing means carried by either the valve disk or the valve body. However, it still remains a problem to achieve the necessary accuracy in machining and dimensioning to be able to control the positioning of the disk relative to the seat in order to achieve the necessary accuracy of alignment for a tight seal. This alignment problem becomes even more apparent with large diameter valves, non-circular valves, or any valve which uses a split stem mounting arrangement for the disk. This split stem arrangement increases the requirements for accuracy in machining of parts as well as increasing the possibility for misalignment of the valve element with respect to the valve seat during assembly, after repair, or after periods of use. 
     SUMMARY OF THE INVENTION 
     The present invention overcomes the above-mentioned requirement for accurate machining and tight tolerances by providing a means whereby the valve element can be adjusted with respect to the valve seat to ensure a tight sealing fit therebetween. The present invention, which is applicable to many styles of valves, is formed by a closure element assembly to be mounted in a valve housing which defines a flow passage therethrough and an annular seat in surrounding relationship to the flow passage. The closure element assembly includes a closure member having a circumferential profile adapted to mate in sealing relationship with the valve seat, at least one hub secured to the closure member and having a profiled-through bore receiving a valve stem therein, the valve stem being rotatably mounted in the valve body and extending along a diameter of the flow passage, and means for adjustably securing the closure member to the valve stems formed by at least two generally opposing threaded passages intersecting the bore and threaded members received in each passage to engage the valve stem providing relative positioning thereto by the degree of insertion of each threaded member in their respective passage. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will now be described by way of example with reference to the accompanying drawings in which: 
     FIG. 1 is a section view taken along line 1--1 of FIG. 2; 
     FIG. 2 is a plan view of a butterfly valve incorporating the present invention; 
     FIG. 3 is a detailed section taken along line 3--3 of FIG. 2; 
     FIG. 4 is a detailed section taken along line 4--4 of FIG. 3; 
     FIG. 5 is a section through an alternate embodiment of the hub; and 
     FIG. 6 is a side elevation of the hub of FIG. 5. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The present invention has been shown as it would be utilized in a standard round butterfly control valve. It should be noted that the invention could be used in butterfly valves of other shapes and would be particularly useful in obround butterfly valves. The invention could also be used with other types of valves, particularly where it is desirable to relax tolerances and/or reduce machining requirements without any loss in sealing effectiveness. 
     The valve 10 is formed by a valve body 12 and a closure assembly 14. The valve body is a rigid member defining a fluid flow passage 16 with a cylindrical neck 18 extending radially from one side of the body and topped by an enlarged mounting flange 20. Opposite the cylindrical neck 18 is a boss 22. A first bore 24 is formed in neck 18 and a second bore 26 is formed in boss 22, both bores being in axial alignment along a diameter of passage 16. The bore 26 is closed at its lower end by plug 28. An annular seating surface 30 surrounds the flow passage 16. The valve closure assembly 14 is formed by a disk member 32 defining a sealing surface 34 profiled to be received in the annular seating surface 28. An annular groove 36 in the surface 34 receives an O-ring 38 therein. An upper stem 40 is received in first bore 24 of the valve body, while a lower stem 42 is received in second bore 26. The stems 40, 42 are axially aligned extending into the flow passage 16 along a diameter thereof. The upper stem 40 is mounted by a packing ring 44, a bushing 46, packing 48 and bearing 50, while the lower stem 42 is mounted by bearing 52, packing 54 and thrust washer 56. The upper end 58 of the upper stem 40 extends beyond the flange 20 and is preferably profiled to receive thereon a valve actuation member (not shown) such as a turning wheel or linkage. The inner ends 60, 62 of stems 40, 42, respectively, are preferably profiled to a polygonal geometric section, for reasons which will be explained here below. As an alternative, these ends could be profiled to have a roughened, for example, knurled, high friction or textured surface (not shown). 
     The disk member 32 is provided with at least one hub 64, 66 attached to the disk member 32 on opposite edges of one side thereof in alignment with the respective upper stem 40 and lower stem 42. Each hub 64, 66 is provided with a throughbore 68, 70 which preferably is profiled to receive therein the profiled ends 60, 62 of the upper and lower stems 40, 42. Each bore 68, 70 is intersected by at least two generally opposing threaded passages 72, 74, 76, 78. A threaded member 80, 82, 84, 86 is received in each respective passage. 
     In conventional valve assemblies, the closure element is fixedly secured to the valve stems. The mounting of the stems in the valve body determines to a great extent the relative positioning of the valve element with respect to the valve seat along the direction of fluid flow. If there is any inaccuracy in the machining of the valve body or valve stems or mounting of the valve stems in the body, there is no possibility for adjustment to correct for any error. The only adjustment possible is axially of the valve stems, and this will not necessarily effect a tighter sealing engagement with the valve seat. The present invention provides means to adjust the valve element with respect to the valve seat in the direction of fluid flow thereby assuring formation of a good tight seal. 
     The present invention can be utilized when the valve is assembled, when the O-ring 38 or other sealing means is replaced, or whenever it is necessary to improve the sealing action of the valve. When using this invention it is not necessary to manufacture the parts with as close tolerances or high degree of machining as was previously required. Rather, it is possible to assemble the valve in conventional fashion and then to adjust the relative positioning of the closure member with respect to the valve seat by appropriate adjustment of the threaded members 80, 82, 84, 86 against the inner ends 60, 62 of the valve stems 40, 42. The planar surfaces of the polygonal profiles provide purchase for the threaded members. It will also be appreciated that these adjustements will, to a certain degree, allow for compensation for warped closure members which heretofore would have provided an unsatisfactory seal. 
     While two hubs have been shown, it is clearly within the purview of the present invention to provide a single, centrally located hub with a single valve stem spanning the entire diameter of the flow passage. In such a case, the valve stem might preferably have a knurled, textured or other friction gripping surface rather than the geometric profile illustrated in order to enable easier passage of the stem through the bore of the hub. This surface would provide a suitable grip for the threaded members, much in the same fashion as the previously described flat surfaces of the geometric profile. 
     As a further alternative, as shown in FIGS. 5 and 6 the hub 88 could be made with a base portion 90 integral with the disk member 92 and a cover portion 94 assembled therewith by attachment means, such as bolts or screws 96 engaging the base portion 90. The base portion 90 and cover portion 94 could together define a profiled bore 98 in the manner of the bore illustrated. Threaded passages 100, 102 would be in the base portion 90 and cover portion 94, respectively. 
     As a still further alternative, the present invention could be provided with more than the illustrated two threaded passages intersecting the bore of the hub. Each such passage would be provided with an appropriate threaded member. Such an arrangement, for example with three threaded passages and members, might prove to provide more accurate alignment than previously possible, especially in the case of smaller valve assemblies. 
     It is expected that the threaded members 80, 82, 84, 86 engaging in threaded passages 72, 74, 76, 78, respectively, will provide an adequate seal. It is, of course, possible to provide an additional seal (not shown) which preferably will be of a removable type to allow future access to the threaded member beneath it. Permanent seals, such as epoxy, could be used if the need arose. 
     The present invention may be subject to many modifications and changes without departing from the spirit or essential characteristics thereof. The above-described embodiment should therefore be deemed to be illustrative and not exclusive as to the scope of the invention which is defined by the appended claims.