Patent Publication Number: US-4225112-A

Title: Butterfly valve with a retaining ring

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates generally to butterfly valves and more particularly to a butterfly valve having a retaining ring for preventing unwanted ejection of the bearing between the shaft and the housing of the butterfly valve. 
     Butterfly valves have historically been provided with seals and bearings between the housing and the shaft. The bearing generally supports the shaft and the seal prevents fluid from leaking along the shaft to the bearing. It has been found that fluid pressure within the butterfly valve may build up behind the seal and bearing causing the bearing to eject from the valve in a bullet-like manner. 
     As a general rule, the valve actuator is located on the shaft and may stop the bearing from causing any serious injury or damage. However, in situations where the actuator has been removed from the valve shaft, the ejection of the bearing from the valve could easily cause serious personal injury or property damage, either from the bearing itself or the resultant expulsion of pipeline fluid and pressure. 
     SUMMARY OF THE INVENTION 
     Thus, a butterfly valve has been provided having a disc with a hub. The disc is adapted to be rotated between an open and closed position. A housing has a valve seat that is adapted to engage the disc in the closed position. A shaft has one end affixed to the hub and extends outwardly of the housing to permit torque to be transmitted to the disc from a point external thereof. A seal is provided for preventing fluid from passing between the shaft and the housing. A bearing supports the shaft in the housing at a point where the shaft extends outwardly over the housing. A retaining ring frictionally engages the shaft and abuts the bearing to insure that fluid leaking along the shaft does not eject the bearing and cause injury. 
     OBJECTS OF THE INVENTION 
     An object of the present invention is the provision of a butterfly valve having a means for protecting persons and property adjacent the valve in cases where high pressure caused ejection of bearing and fluids from the valve. 
     Another object of the present invention is the provision of a butterfly valve having the safety feature referred to above and yet being relatively easy to assemble. 
     Still another object of the present invention is the provision of a butterfly valve having the safety feature referred to above and being relatively inexpensive to manufacture. 
     Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows a longitudinal cross section view of the butterfly valve of the present invention. 
     FIG. 1A shows a top view of a retaining ring shown in FIG. 1. 
     FIG. 2 shows a longitudinal cross section of the valve seat and bearing assembly of the butterfly valve shown in FIG. 1. 
     FIG. 2A shows a modified end structure on the ring illustrated in FIG. 2. 
     FIG. 3 shows a partial longitudinal cross-sectional view of the valve seat and valve housing of the butterfly valve shown in FIG. 1. 
     FIG. 4 shows a plan view of the valve shaft of the butterfly valve shown in FIG. 1. 
     FIG. 5 shows a front view of the shaft shown in FIG. 4. 
     FIG. 6 shows an enlarged partial front view of the shaft shown in FIG. 4. 
     FIG. 7 shows a longitudinal cross-sectional view of the valve disc of the butterfly valve shown in FIG. 1 as the shaft shown in FIG. 4 is being inserted in. 
     FIGS. 8 and 9 show in schematic form the method of making the valve shaft of the present invention. 
     FIG. 10 shows a portion of the butterfly valve including an alternate retaining ring. 
     FIG. 11 shows a top view of the retaining ring shown in FIG. 10. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 shows a butterfly valve 20 including a disc 22 adapted to be rotated between an open and a closed position. A valve seat 24 made of resilient material, preferably rubber, surrounds the disc 22 and is adapted to engage the disc when the valve is in the closed position. A shaft 26 has one end 28 affixed to the disc 22 at hub 29 and extends outwardly therefrom. The other end of shaft 26 is connected to an actuator of any desired type (not shown). As is best seen in FIG. 2, the valve seat 24 includes an outer wall 25 having a pair of apertures 30 and 32 therein. The shaft 26 extends through the aperture 30 and a second shaft 34 is affixed to the bottom of disc 22 and extends outwardly therefrom through aperture 32. A ring 36, preferably made of steel, surrounds the outer wall 25 of valve seat 24 and is permanently affixed thereto, preferably by vulcanization, in order to prevent deformation of the outer wall of the valve seat. It is important that the ring 36 be made of a material that is much stronger and much more rigid than the valve seat 24. Preferably, ring 36 should be strong enough to support the rated pressure of the valve, even without the housing. The ring 36 further includes a pair of cylindrical lips 38 and 40, each defining an aperture in the ring. The cylindrical lips 38 and 40 are located snugly within the apertures 30 and 32, respectively. A cylindrical collar 42 surrounds the shaft 26 and is positioned within the cylindrical lip 38 in such a manner that the lip 38 supports the collar 42 and the collar 42 in turn provides a bearing surface for the shaft 26. Likewise, a cylindrical collar 44 surrounds the shaft 34 and is positioned within cylindrical lip 40 in such a manner that the lip 40 supports the collar 44 and the collar 44 in turn provides a bearing surface for the shaft 34. 
     It is a particularly important feature of the present invention that by inserting the collars 42 and 44 into the valve seat 24, the bearing surfaces provided for the shafts 26 and 34 respectively are positioned as close as possible to the disc 22. This has the greatly beneficial affect of reducing bearing loads by minimizing the moment between the shaft and the bearing. It has the additional beneficial affect of making it easy to align the bearings with the shaft. The collars 42 and 44 are also preferably vulcanized into the valve seat 24 to create a unitary structure with the valve seat 24 and the ring 36. The upper and lower apertures 30 and 32 in the outer wall of valve seat 24 includes a means for sealing the outward portion of the shaft 24 from the disc 22 whereby fluid is prevented from leaking along the shaft 26. This is accomplished by radially extending flange 46 extending inwardly from the walls of the aperture 30 near the top of the disc 22. The end of the cylindrical lip 38 and the end of the collar 42 abut the top surface of the flange 46, which has an inside diameter that is slightly smaller than the inside diameter of collars 42 and 44. The inner surface of the projection 46 contacts the shaft 26 above spline 70 to effectively seal the shaft 26 from the disc 22, due to radial compression of the elastomeric flange 46. 
     Referring to FIG. 2A, there is shown a modified ring 36&#39;. In situations where the bearing loads are increased, such as in larger butterfly valves, a cylindrical member 38&#39; may be welded to ring 36&#39;. The member extends radially inwardly and outwardly of ring 36&#39; for added support for collar 42. 
     As is best seen in FIG. 3 the valve seat 24 includes a pair of flanges 50 and 52 on the axial ends thereof projecting radially outwardly from the outer wall 25. The ring 36 is positioned between the flanges 50 and 52 and spaced therefrom creating a pair of grooves 54 and 56, with one groove being on each side of the ring 36. At this point it should be apparent that the disc 22, the valve seat 24, the shafts 26 and 34, the ring 36, and the collars 42 and 44 form a unitary valve assembly or cartridge. 
     The butterfly valve 20 further includes a housing having an upper section 60 and a lower section 62. Each of the sections 60 and 62 includes a pair of projections 64 and 66 on the inner surface thereof for mating with the pair of grooves 54 and 56 respectively. The sections 60 and 62 are joined, preferably by bolting, and cooperate with the ring 36 and the outer wall 25 of the valve seat 24 to hold the unitary valve assembly within the housing. Thus, the butterfly valve of the present invention is provided with the important constructional feature of having a complete valve cartridge within the valve housing which may be removed easily for servicing or replacement. Additionally, since this valve cartridge includes a rigid retaining ring which cooperates with the valve housing, the valve may be utilized for dead-end service. This is so since even should the valve be in the closed position and the conduit downstream of the pressure be removed from connection to the valve 20, the valve cartridge of the present invention is sturdy enough to retain rated pressure without being deformed radially, or displaced axially because of the cooperation of ring 36 and projections 64 and 66. 
     As is shown in FIGS. 4 through 9 the butterfly valve 20 includes an improved connection between the shafts 26 and 34 and the disc 22. For simplicity the connection will be described with regard to shaft 26. The end 28 of shaft 26 which connects with disc 22 includes a plurality of splines 70 for securing the shaft 26 to the disc 22. The height of each of the splines 70 is defined as the space between a plane tangent to the outer surface of the spline 70 and a plane parallel to the aforementioned plane and tangent to the imaginary continuation of the grooves 72 interspersed between splines 70. This is illustrated as &#34;h&#34; in FIG. 6. It is significant that this dimension &#34;h&#34; be no more than 0.030 inches. This figure is derived by adding the maximum interference between the splines and the hub, 0.025 inches, plus approximately 0.005 for tolerances. Should the interference exceed 0.025 inches, the cutting stresses during shaft installation become unacceptable. While a clearance between groove 72 and hole 88 is not required, it is desirable to vent gas that may be trapped in cavity 78. Clearance between bore 88 and the surface 72 provides for venting of air. The interference between the splines and the hub is preferably 0.011 inches and the tolerance is preferably 0.003 inches. The clearance is preferably 0.005 inches. Each of the splines 70 includes a cylindrical top surface portion 75 and two side walls 74 and 76 extending therefrom toward the body of the shaft at an angle with respect to the plane tangent to the top surface portion at the center thereof. This angle, illustrated as α in FIG. 6, is between 30 and 60 degrees and is preferably 45 degrees. The reasons for the above dimensional constraints are that it is important to minimize the amount of material removed from the disc 22 during the process of inserting the shaft 26 while at the same time attaining a strong joint. Additionally, it is important not to place undue stress on the disc 22 during this operation. 
     Since there will be some removal of material during the insertion of shafts 26 and 34 into disc 22, it is important that the disc 22 be provided internal cavities 78 and 80 for receiving any material removed from the interior of the disc during the process of joining the shafts to the disc. Since the shafts 26 and 34 must cut into the disc 22 it is imperative that these shafts have a hardness greater than the hardness of the disc 22. It has been found that the minimum difference between the hardness of the shaft and the hardness of the disc should be approximately 5 on the Rockwell C scale, with the shaft being the harder material. For example, the shaft may be made out of steel having a Rockwell C hardness greater than 33 and the disc may be made of cast iron having a Rockwell C hardness less than 27. It is also preferable that the length of the splines is approximately one and one-half times the diameter of the shaft and the width of the splines is approximately one-quarter to approximately one-third the diameter of the shaft. For example, a shaft one-half inch in diameter could have six splines, each 0.158 inches wide and three-quarters of an inch long. Thus, the circumference of the shaft will determine the number of splines there are. 
     As is most apparent from FIG. 7 the present valve is of the stub shaft type and thus valve disc 22 is formed with hub portions 82 and 84 having increased thickness relative to the main portion 86 of the disc. The portions of increased thickness 82 and 84 are adjacent the circumference of the disc 22. In smaller valve sizes (such as less than approximately three inches) the hubs may run together into one continuous cylindrical surface. The method of joining the shafts to the disc will be described only with respect to shaft 26, it being understood that the same process applies to shaft 34. A hole 88 is drilled in the portion 82 of disc 22. The hole 88 has a diameter which is smaller than the diameter of the shaft 26, but larger than the shaft surface diameter 72 to provide clearance. A slightly larger hole 90 is drilled as a pilot hole to facilitate the insertion of the shaft 26, and to allow for the &#34;start&#34; area of the splines, after the shaft is installed. As is shown in FIGS. 8 and 9 splines are formed on the end 28 of shaft 26 by cutting tool 92. The cutting tool 92 includes a plurality of cutting elements 94 for cutting grooves in the shaft 26. The shaft 26 is then pressed into hole 88, as is illustrated in FIG. 7 thereby utilizing the splines 70 to cut grooves in the side walls of the hole 88 to form a permanent joint between the shaft and the disc. The resultant connection exceeds the torque transmitting capability of the shaft 26 and the strength of the disc 22. 
     At the other end of shaft 26, there is provided a unique bearing retainer assembly 100. As is best seen in FIG. 1, assembly 100 includes an elastomeric &#34;O&#34; ring 102 compressed radially between shaft 26 and cylindrical bore 122, with bearing 106 and shoulder 104 forming the walls of an &#34;O&#34; ring groove. &#34;O&#34; ring 102 and bearing 106 may be made of any suitable material such as rubber and bronze, respectively. In order to insure that fluid leaking along shaft 26 does not eject bearing 106 and cause personal injury or property damage, a retaining ring 108 is provided, abutting bearing 106. Referring to FIG. 1A, retaining ring 108 includes a split ring portion 110, engaging shaft 26, having ends 112 and 114. Each of ends 112 and 114 includes a hole 116 and 118, respectively. These holes may be used in assembling and disassembling retaining ring 108 on shaft 26. By merely inserting projections into the holes, retaining ring may be opened and closed. The retaining ring may be made of any suitable material, such as carbon spring steel (SAE 1060-1090). The retaining ring exerts a frictional hold against axial displacement. Should fluid pressure become sufficient to eject bearing 106, the frictional grip of retaining ring 108 on shaft 26 will stop axial movement of bearing 106, because the shaft 26 is firmly retained in the valve disc 22 as described earlier. 
     It may be desirable, as an added precaution, to provide an annular groove 120 in shaft 26 adjacent to retaining ring 108. In this case, even if a sudden high leakage pressure were sufficient to slide retaining ring 108 along shaft 26, retaining ring 108 (being sprung) would seat itself in groove 120 which prevents further axial movement of the retaining ring. The width of the groove should be at least slightly wider than the width of the retaining ring so that the retaining ring will easily fall into the groove. For example, the groove should be at least approximately 0.030 inches wider than the retaining ring. 
     It is significant that the groove be spaced axially from the retaining ring. Since the groove is formed prior to assembly, it would be difficult to estimate the precise location of the retaining ring. By spacing the groove from the retaining ring the manufacturing process is simplified. 
     Referring to FIGS. 10 and 11, there is shown a modified retaining ring 108&#39;. In many cases, such as with small butterfly valves, it may be sufficient to use a retaining ring such as the one illustrated in FIGS. 10 and 11. This retaining ring 108&#39; includes a circumferentially extending portion 122 with a plurality of radially extending fingers 124. Retaining ring 108&#39; may be slid over shaft 26 with relative ease since radially extending fingers 124 extend axially away from the direction of travel of the retaining ring as it is installed on shaft 26. Retaining ring 108&#39; may be made of any suitable material, such as carbon spring steel. While it has not been illustrated in FIG. 10, it may be desirable to include an annular groove on shaft 26 similar to the one that is used with respect to retaining ring 108. 
     Should fluid pressure become sufficient to eject bearing 106, the frictional grip of retaining ring 108&#39; on shaft 26 will be increased by the force of bearing 106 on the back of fingers 124 to stop ejection of bearing 108. 
     While there has been described what is at present considered to be the preferred embodiment of the present invention, it will be obvious to those skilled in the art that various changes and modifications may be therein, without departing from the invention, and it is, therefore, deemed in the appended claims to cover all such changes and modifications as followed in the true spirit and scope of the invention.