Patent GB-780908-A (GB)
Title: Mechanical shaft seal
IPC: F16J15/38
Filed: 1955-09-29
Abstract: 780,908. Stuffing-box substitutes. GARLOCK PACKING CO. Sept. 29, 1955 [Feb. 2, 1955], No. 27746/55. Class 122 (5). The gap where a rotary shaft 10 passes through an opening 14 in a fixed part 17 is sealed by a device comprising two coaxial sleeves 56, 64 disposed one within the other in spaced relation and connected intermediate their ends by means providing a fluid-tight joint between them, and, at each end of this assembly, a sealing ring 92 which is connected to one of the sleeves by means permitting it to slide axially of the assembly, extends freely into the adjacent annular space 74 between the two sleeves with a packing ring 110 disposed between the opposed axially-extending surfaces of the sealing ring and one of the sleeves, and is urged by a spring 100 disposed in the annular space so as to maintain it in rotative-sliding engagement with a sealing seat 102. The invention is described as applied to the sealing of a shaft 10 which at its lower end (the right in the Figure) extends into a container 17 and carries an agitator for mixing liquids therein ; the two sleeves 56, 64 are disposed on and around the shaft in the neck portion 16 of the container and a bearing cap 28 secured to this portion holds all the parts in position. The inner sleeve 56, which is keyed on the shaft between a flange 46 and metal stop ring 88, has an outer radial flange 58 closely fitting against the inner face of the outer sleeve (with the interposition of a sealing ring 78) and a shoulder 66 thereon, the two sleeves being connected by a pin 68. In the annular space 74 on each side of the flange 58 the spring 100 abuts a sleeve portion 98 on the sealing ring 92 so as to,urge the nose 94 of the latter into sealing engagement with the seat 102. A set-screw 116 screw-threaded in the ring and engaging an axially-extending slot in the sleeve 64 connects the ring and sleeve for joint rotation, but permits relative axial movement of the ring, and the packing ring 110 providing a fluid-tight joint between the opposed faces of the sealing ring and outer sleeve 64 is associated with an anti-extrusion washer 114. The sealing seat 102, which may be of carbon or metal, is disposed within an annular recess of a carrier 106 housed in an annular recess in the neck 16 of the container ; the carrier 106 is held against rotation by axial pins 124 and sealed at its outer periphery by a ring 120, and the seat 102 is sealed in position by outer and inner rings 130, 138. In operation, any gas above the liquid in the container passes through the clearance space 12 around the shaft into the annular recess 74 between the sleeves and the annular space 74x bounded by the sealing ring 92 at the right-hand of the Figure and so augments the action of the spring 100 in maintaining sealing contact between the ring and seat 102. The sealing effect is still further augmented by supplying liquid, such as oil, at higher pressure than that of the gas through a duct 144 in the neck 16 into the annular space around the outer sleeve 64 and space 19x at the back of the nose 94 of the ring 92 ; an exhaust line for liquid or gas leaking past the sealing rings 120, 138 is provided through one or more ducts 146. The principal purpose of the seal at the left-hand end of the sleeve assembly is to prevent leakage of sealing liquid outwardly along the shaft to the end bearing 32, and, if desired, to compensate for the absence of the gas at that end the sealing effect there may be increased by increasing the compression of the spring 100 and/or altering the design of the ring and seat. The sleeve portion of either or both sealing rings 92 may be formed with a counterbore to receive the spring.