Patent GB-742013-A (GB)
Title: Lubricated rotary plug valve
Inventor: CLADE ROBERT
IPC: F16K5/22
Filed: 1953-05-14
Abstract: 742,013. Valves. W.K.M. MANUFACTURING CO., Inc. May 14, 1953, No. 13501/53. Class 135. In a lubricated rotary plug valve having a groove system which receives lubricant through a check valve 62, Fig. 1, from a lubricant chamber in the plug B, a safety valve device is provided for venting excess lubricant into the atmosphere from the lubricant chamber instead of permitting it to pass into the groove system through the check valve, such safety valve device comprising normally engaging seating surfaces 16, 44 provided on the plug B and the plug casing A respectively, such surfaces separating on axial movement of the plug under excessive lubricant pressure. The plug B has an upper stem 40 projecting with clearance through the top of the casing A, and surrounded by a sealing ring 48 of circular cross-section urged towards the stem and the wall of the bore 10 accommodating the stem by the pressure of the fluid controlled by the valve. The upper stem 40 has an enlarged portion 42. The plug B has a through passage 52 and also a lower stem or stub shaft 38. The sealing ring 48 is accommodated in a groove 46. The seating surface 44 is formed on the enlarged part 42 and is pressed against a machined surface 16 on a shoulder 12 of the valve casing by a spring 26 arranged in a base cap 20 having an axial aperture 22. Sealing ring 50 similar to ring 48 is arranged in a recess 30 in the cap 20 and is similarly pressed against the stub shaft 38 and the walls of the recess 30 by line pressure. The rings 48, 50 are of rubber, or other resilient material. The valve plug is lubricated by means of a screw or jack 64 which forces lubricant at high pressure through the lubricant chamber and past a ball check valve 62 into radial holes 58. The holes 58 communicate with long longitudinal grooves 56 which intersect the chamfered ends 66 of the plug and thereby have access to the end faces of the plug. Diametrically opposite shorter grooves 54 in the plug communicate by dwarf grooves or cavities 69 with the end faces of the plug in the open and closed positions only. Radial holes 68 are provided on the inlet side of the check valve 62, so that when the plug moves axially downwards due to the superior lubricant pressure developed in the upper end space of the valve casing consequential on the viscous drag of the lubricant in the grooves 54, 56, lubricant is expelled through the holes 68 and between the surfaces 16, 44. The plug shown is substantially balanced axially as regards atmospheric pressure and line pressure, but in a modification, Fig. 4, the stub shaft 38 is of reduced diameter so that the line pressure exerts a net upward force to aid the spring 26. In this form two shoulders 80, 81 are arranged between the plug 36 and the enlarged part 42 of the stem. The upper sealing ring 78 lies adjacent the shoulder 81 and the space beneath the ring is supplied with lubricant directly from the holes 58 by passages 82. In a further modification, Fig. 2 (not shown), the chamfers 66 are dispensed with, and the grooves 56 are connected with the plug end spaces by narrow dwarf grooves in the plug, those at its upper end being of greater crosssection than those at its lower end. In another modification, Fig. 6 (not shown), two sealing rings are provided at the top end of the plug. Fig. 3 (not shown) discloses a form with an upper sealing ring substantially of T-shape. In a still further modification, Fig. 5 (not shown) the holes 68 are replaced by inclined bores stopped at their outer ends and communicating with short longitudinal passages having flared ends opening into the surface 44. Specification 436,715 is referred to.