GB580127A - Improvements in or relating to hydraulic shock- or vibration-dampers - Google Patents

Abstract

580,127. Vibration-dampers. WEDGE, H. F., and AINSLIE, K. O. April 24, 1944, No. 7600. [Class 108 (iii)] An hydraulic vibration-damper comprises two elements having opposed parallel faces and mounted for relative movement in the plane of and normal to their faces, spring means biassing the elements to move together so that their faces engage, and means for supplying a viscous liquid between the faces which wets both faces and forms a film between them. Fig. 1 shows a damper for a vehicle suspension comprising a casing 10 adapted to be secured to the vehicle chassis and a tubular shaft 15 mounted in bushes 16, 17 in bearings 11, 13 and having an arm 19 connected for movement with a road wheel. A number of spaced, flexible, annular plates 20 carrying annular damping discs 23 are fixed inside the casing by bolts 24 and intercalated therewith are a number of flexible plates 27 mounted on the shaft 15 and carrying damping discs 29. A rigid pressure plate 31 also mounted on the shaft, is secured thereto, together with the plates 27, by bolts 32 and is biassed to press the damping discs together and against a part 25 of the casing, by a spring 33 which is mounted in compression inside the shaft 15 between a pad 34 and a screw-adjustable abutment 35. To ensure that liquid films are formed between the damping faces of the discs, after the parts are assembled, liquid is forced into the casing through a nipple 37 and can only completely fill the casing and be extruded through a normally-closed opening 38, by passing between the opposed damping faces. To assist the formation of the films, opposed damping faces are formed with oppositely-inclined grooves. A pump which may be of the oscillatory vane type, operated by movement of the shaft, may maintain the films between the faces by forcing liquid from one part of the casing to the other. Figs. 4 and 5 show a reciprocating type of damper in which two fixed damping plates 52 and a pressure plate 53 mounted on bolts 55 in a rectangular casing 50, are urged by springs 62 into engagement with three movable damping plates 57 which are hinged by a pin 58 to a reciprocable rod 59. All the plates fit closely against the top and bottom of the casing and the pressure plate 53 extends the full length to divide the casing into a left-hand space 63, a right-hand space 64, and a space 65 immediately inside the cover Four ports 66 are formed in the plate 53, two at each end, and are controlled by spring-loaded valves 67 so arranged that one at each end opens into the space 65, while the other, which is lightly loaded and acts merely as a non-return valve, opens out of that space. The casing is filled with liquid through a nipple 68 so that space 63 is first filled and when the pressure therewithin rises sufficiently, part of the liquid passes the valve 67 to the space 65 and part is forced between the damping faces of the plates 52, 53, 57. When space 65 is full, liquid passes the lightly-loaded valve 67 at the right-hand end of plate 53, into space 64. During operation, the plates 57 act as a pump piston to compress liquid in the space 63 or 64 which causes a flow of liquid between the damping faces of the plates to maintain the liquid films. To give dashpot damping as well as viscous damping, the ports 66, 67 may be omitted and a leak provided between the spaces 63, 64.