Patent GB-460020-A (GB)
Title: Improvements relating to shock absorbers
IPC: F16F9/14
Filed: 1935-07-16
Abstract: 460,020. Shock - absorbers. TRIGGS, W. W. (Pennington Engineering Co.) July 16, 1935, No. 20259. [Class 108 (iii)] In a hydraulic shock-absorber for motor vehicles two separate automatic controlling devices arranged in series are provided for controlling the flow of liquid through a conduit extending from one side of a vane or piston to the other, one device being adapted to offer small and large resistances respectively to the first part and intermediate part of the movement of the vane or piston away from and back to its normal position, and the other device being adapted to maintain, at an intermediate value between the small and large resistances, the resistance to the movement in the spring-rebound direction, in the region of the normal position of the vane or piston. A rotaryvane shock-absorber is formed, as shown in Figs. 1, 2 of front, rear, and intermediate plates 3, 1, 2 positioned by dowel pins 5 and connected together by bolts 4, the plates 2, 3 bemg enclosed by a metal casmg 10 which provides a reservoir C. A groove 22 in the upper part and the automatically-controlled conduit in the lower part of the plate 1 provide direct communication between the working chambers A, B respectively and the reservoir C. Tapered recesses 2<c>, 2d in the plate 2 cooperating with the conduit 17, 18 in the vane hub form one of the controlling devices while the other comprises a ball 19 arranged with slight clearance in a metering passage 13<a> in the conduit. In operation, on clockwise movement of the vane 6a, Fig. 2, corresponding to compression of the supporting springs, fluid is forced from chamber B through the recess 2d and into passage 18 the resistance increasing as the end of the passage approaches the inner end of the recess. On passing into the passage 13a the fluid forces the ball 19 against an abutment 14a and passes with negligible resistance around the ball into the passage 17 and thence into chamber A. On reverse movement of the vane corresponding to rebound of the vehicle springs fluid from chamber B passes, at first, freely through passage 17 and into passage 13a forcing the ball 19 against a spring-pressed and/or adjustable abutment 20 which projects further into passage 13a than the abutment 14a. The peripheral clearance around the ball 19 is correspondingly less sc that resistance to flow of fluid is greater. The fluid passing the ball is further resisted owing to the position of the passage 18 relatively to the recess 2d, the resistance decreasing as the movement of the vane continues. In the region of the normal position of the vane the only resistance is that due to the position of the ball 19 and abutment 20. As shown, the abutment 20 is spring-pressed so that changes in fluid viscosity due to changes in temperature are compensated for, the strength of the spring, which is adjustable, determining the resistance. In a modification, the metering throat is formed integral with and the abutment 20 is screwthreaded in the casing so that rebound resistance varies with fluid viscosity unless the abutment is composed of material such as ebonite, having a high coefficient of expansion. Moreover, one or two radial passages 33, 34, Fig. 8, controlled by non-return valves 33<1>, 341 are provided which communicate with the axial bore 27 at the outer and inner sides respectively of the throttling throat, so that the resistance to rebound is determined entirely by the position of the ball 19. In a further modification the abutment 14a is replaced by a light spring which normally presses the ball 19 against the abutment 20. Fig. 13 shows a further construction in which the metering valve 65 is formed with a spring- pressed stem 66 extending loosely through the yieldable abutment 67 to which a cap 67b is screwed for limiting the movement of the stem. In another construction, Fig. 14, the metering valve 79 is fixedly mounted in the axial bore 74 of the vane and the metering throat 75 is axially movable and engaged by oppositely-acting strong and weak springs 77, 80 respectively.