Patent GB-584954-A (GB)
Title: Improvements in shock absorbers
IPC: F16F9/48
Filed: 1944-08-23
Abstract: 584,954. Hydraulic shock-absorbers. GENERAL MOTORS CORPORATION. Aug. 23, 1944, No. 16051. Convention date, Sept. 22, 1943. [Class 108 (iii)] In a hydraulic piston-and-cylinder shockabsorber having a reservoir in communication with the cylinder, the piston is provided with a plurality of passages for flow of fluid from either side thereof to the other and spring-pressed valves for controlling the respective fluid flows, and the cylinder contains valve members which at predetermined points in the piston stroke reduce the fluid flow through the passages to the respective spring-pressed valves. As shown, the piston 90 and rod 70 reciprocate in a cylinder 20 which is surrounded by another cylinder 24 to provide -an annular reservoir 25 closed by end members 21, 37. The piston-rod 70 passes through packing 28 in a recess 26 in the end member 21 from which ducts 29 lead to the reservoir 25, extreme fluid agitation in which is prevented by a washer 69. Three stages of resistance are provided to compression of the shock-absorber and two to extension, the three resistance stages being effected respectively by valve means on the piston, by further valve means 166 extending from the piston to co-operate with an apertured closure 35 at the lower end of the cylinder, and by valve means 67 spring-suspended in the lower part of the cylinder, while the two resistance stages to extension are effected by valve means on the piston and by valve means 152 spring-suspended in the upper part of the cylinder. Piston construction. The piston 90, which is mounted between spacing collars 82, 87 on the reduced end of the rod 70, is formed with twelve radial passages 100-111 from which various axial passages lead to both ends of the piston, namely, as shown in Fig. 6, inner passages 121, 123, 125, 127, 129, 131, intermediate passages 122, 128, and outer passages 120, 124, 126, 130 to the lower end of the piston, and, as shown in Fig. 7, inner passages 200, 202, 204, 206, 208, 210, intermediate' passages 203, 207, 211, and outer passages 201, 205, 209 to the upper end of the piston. The two inner series of passages are normally closed by spring-pressed valves 84, 89 , slidably mounted on the collars 82, 87. The valve 166 is loosely mounted on a spindle 163 which is slidable in a bore 160 in the pistonrod, the valve and spindle being maintained normally by a spring 167 in the position shown in Fig. 1. Cylinder valve assembly. The lower end closure 35 is formed with six inner ports 42, Fig., 2, normally closed by a spring-pressed valve 58 slidable on a stud 56 and with an outer series of ports 43 normally closed by a spring-pressed annular plate-valve 46, the ports connecting the cylinder with passages 40 leading into the reservoir 25. The valves 67, 152 are held spaced from the ends of the cylinder by springs 62, 151 respectively. Operation. On compression, during the first resistance stage, fluid is forced through the piston passages 120, 122, 124, 126, 128, 130 and their corresponding radial passages 100, 102, 104, 106, 108, 110 to the exhaust passages 200, 202, 204, 206, 208, 210, from which flow is restricted by the valve 84. Owing to the increasing volume of the cylinder taken up by the entry of the piston-rod 70, fluid is also forced from the lower end of the cylinder through the ports 42 against the restricting action of the valve 58. As the compression of the shock-absorber continues, the valve 166 eventually engages the closure 35 closing all but two of the passages 42, thus commencing the second increased resistance stage which continues until the piston engages the floating valve 67. This closes the piston passages 120, 124, 126, 130 and partly closes the passages 122, 128, thus effecting the third stage of maximum resistance to compression. An extension, during the first resistance stage, fluid is forced through the piston passages 201, 203, 205, 207, 209, 211 into the communicating radial passages 101, 103, 105, 107, 109, 111 and thence through the exhaust passages 121, 123, 125, 127, 129, 131 from which flow is restricted by the valve 89. Fluid also enters the lower end of the cylinder from the reservoir through the passages 40 and ports 43, lifting the annular plate-valve 46 against the action of the spring 47. When the piston engages the floating ring valve 152, the second resistance stage commences, the valve completely closing the piston passages 201, 205, 209 and partly closing the passages 203, 207, 211.