Patent GB-661269-A (GB)
Title: Improvements in or relating to a hydraulic shock absorber
IPC: F16F9/34
Filed: 1947-08-11
Abstract: 661,269. Hydraulic shock-absorbers. HOUDAILLE-HERSHEY CORPORATION. Aug. 11. 1947 [Jan. 8, 1947], No. 22231/47. Class 108(iii) A shock-absorber comprises a piston body slidably received on the endportion of a piston rod having shoulder means against which the piston is clamped by a nut member threaded on the extremity of the rod, a fluid passage through the rod preferably byepassing the piston and opening axially through the extremity of the rod, a guide rod supported by the nut and extending preferably into the passage and a valve member slidable on the guide rod and controlling the flow of fluid through the passage. In the construction shown in Fig. 2, the piston comprises a body member 15 secured to the end of a piston rod 17 by a nut 49 and a split ring 51. A circumferential series of six ccmpression-now ducts 52 in the body 15 open into a common annular channel 54 on which is seated a disc-type compression valve 55. A valve spring 57 having eight circumferentially spaced spring fingers which resist upward movement of the valve 55, is held between a spacer member 59 and an annular ring 60 which is recessed in order to engage the ring 51. Rebound flow occurs through passages 62, 67, 71 in the piston rod, and is controlled by a valve 63 slidable on a stem 72 the lower end of which is secured by riveting to a spider portion 70 of the nut 49. The valve 63 seats on a shoulder formed between the passages 62, 67 and is urged into the closing position by a spring 68 of such strength that greater resistance is offered by the valve 63 to rebound flow than is offered by the valve 55 to compression flow. Flow for low rates of relative compression or rebound movement, may occur through a permanently open passage formed between the inner periphery of the valve 63 and an axiallyextending flattened portion 77 of the periphery of the stem 72. In a modified construction, Fig. 4 (not shown), the permanently open passage is replaced by a series of bleed orifices formed in the valve 55. The piston rod extends through a closure member 24, Fig. 2, of the cylinder 16, Fig. 6, and the latter is surrounded concentrically by a clyindrical casing 19 which defines a reservoir 132. Slots 42a in the member 24 allow the escape of liquid from above the piston into the passages 71 in the piston rod when the piston is in its uppermost position. Flow between the main cylinder 16 and the reservoir space 132 is controlled by a valve casing 32, Fig. 6. which is mounted between the annular end-surface of the cylinder 16 and the frusto-conical sides of a lower closure member 20 which is welded to the outer casing 19, The cylinders 16 and 19 and the casing 32 are held in assembled relation by the closure member 24, Fig. 2, which abuts the other end of the cylinder 16 at 25 and is in threaded engagement (not shown in Fig. 2) with the reservoir casing. Fhe casing 32 is formed with a central port 134 flow through which from the reservoir to the cylinder is controlled by a valve 139 which is held on an annular seating 140 by a relatively light blade spring 153. clamped to a stem 146 rigid with the valve 139. Flow from the cylinder to the reservoir is resisted more strongly by a valve 143 which is held in engagement with an annular seating 145 on the valve 139, and controls flow through ports 142 in the valve 139. Movement of the valve 139 is guided in a counterbore 135 in the casing 32 by radial projections 141. and is limited by lateral projections 155. Fig. 6 (not shown), rigid with the stem 146, which engage the main casing. The spring 153 is replaced in a modification. Figs. 10, 11, by a helical spring 180, and the casing 32 engages three circumferentially spaced pressed-out ribs 160 in the head 20. The valve 143 is seated on the annular seating 145, but a circular port 167. Fig. 10, in the valve 139, is concentric with the seating 145 and has inwardly projecting fingers 169 which provide a bearing for a flow-restricting washer 168. The stem of the valve 139 is riveted over at 171 to the washer 168 and the valve 139, opening movement of which is limited by engagement of a washer 175 with the valve casing. In a further construction, Fig. 8, the valve 139 has a square-shaped port 190 which is restricted by a circular frustoconical head 191 of the valve stem 146. Additional flow between the cylinder and reservoir is provided through passages 200, 204, Fig. 9, in the stem 146. In order to reduce flow noise, the passage 200 has half the cross-sectional area of the passage 204 and is inclined at 10 degrees to the axis of the stem, and opens into a chamber 203. The Specification as open to inspection under Sect. 91 comprises also a further construction of piston, Fig. 5 (Cancelled). in which the valve 63 is replaced by a valve 124 slidably mounted on a retaining nut 107 for the piston body 15. The valve 124 is spring-urged to close rebound flow passages 109 in the piston body. A compression flow valve 112 of similar construction to the valve 55 of Fig. 2, has ports 119 which allow free flow of rebound liquid to the passages 109. The retaining ring 50 is replaced by a shoulder 115 in the piston rod. This subject-matter does not appear in the Specification as accepted.