Patent GB-942328-A (GB)
Title: Improvements in or relating to adjustable hydraulic shock absorbers
Inventor: DAY ALAN ROBERT ANDREW
IPC: F16F9/46
Filed: 1960-12-01
Abstract: 942,328. Hydraulic shock absorbers. ARMSTRONG PATENTS CO., Ltd. Nov. 24, 1961 [Dec. 1, 1960; Sept. 21, 1961], Nos. 41262/60 and 33756/61. Heading F2S. In an hydraulic shock absorber of the kind wherein hydraulic medium displaced during operation of the shock absorber is constrained to flow through restricting passage means including a displaceable restrictor member governing the cross-sectional area of the passage means the shock absorber further comprises an electrically operated stepping mechanism, a driven member which is displaced in discreet steps by the mechanism and which is arranged to displace the restrictor member, and switch means for completing an energizing circuit for the stepping mechanism to advance the driven member from one position to another and therefore de-energize the mechanism. As shown in Figs. 1, 1a a needle valve 10 spaced from a valve seat 12 surrounding an hydraulic medium passage 14, is spring loaded toward a fixed stop member 16, which co-operates with one of the stepped circumferential lands 20, 22, 24 on a circular plate 18 which carries the needle valve 10 and which has peripheral ratchet teeth 26 for engaging with pawls 32 pivoted to a pawl carrier 30. The latter is carried by a solenoid operated plunger 28 with a return spring 36 for restoring the plunger after it has been retracted by the energization of the solenoid. A shaft 38, fast with the plate 18, carries a star wheel 40 and a rotatable wiper element 44 of a switch segment 42 having contacts 1-3 each corresponding to one of the possible settings of the needle valve 10 determined by the lands 20, 22, 24 and also to one of the contacts 1a, 2a, 3a of a remotely positioned, manually operable, switch 48 having a rotatable wiper element 46. A secondary battery 50, carried by a road vehicle, has one terminal connected to the solenoid 34 the other end of which is connected, through interrupter contacts 52, operable by the star wheel 40, to the wiper element 44 of the switch 42. Through the wiper element 44 this end of the solenoid is extended to one of the contacts 1a, 2a, 3a on the switch 48 the second terminal of the battery 50 being connected to the wiper element 46 which is formed with a notch 47. In operation, with the recess 47 opposite the contact 3a as shown, the solenoid is de-energized and the stop 16 abuts against the highest land 20 which results in maximum constriction to flow of hydraulic fluid through the passage 14. If it is desired to change, e.g. to the setting provided by the land 22, the wiper 46 is moved to bring the recess 47 into register with the contact 2a so that the battery 50 is connected through the connections 3a, 3 to the solenoid 34 which is then retracted the left hand pawl 32, Fig. 1, engaging one of the ratchet teeth 26 to rotate the plate 18 in the direction of the arrow 19. The rotation of the plate 18 causes the star wheel to open the contacts 52 in advance of the movement of the wiper 44 off the contacts 3 toward the contact 2 the plunger 28 being restored by the spring 36 so that the right-hand pawl 32 engages the adjoining ratchet tooth 26 to complete the rotary movement of the plate 18, positions the wiper 44 in register with the contact 2, and allow the contacts 52 to close again. Once the switch has been turned to a chosen position the operation of the stepping mechanism is automatic in that the wiper element 44 hunts to the position of the de-energized stationary contact of the contacts 1, 2, 3. In a practical embodiment of the invention, Fig. 3, an auxiliary housing 66, with a cover plate 68, extends into the reservoir space 64 of an uni-directional flow hydraulic shock absorber 60 and has a valve chamber with the passage 14 controlled by the needle valve 10. The solenoid winding 34 with a two part core 28, 29, having an intervening spring 36, is mounted in the upper part of the housing 66 the pawl carrier 30 mounted on the core part 28, being provided with pawls which co-operate with the ratchet teeth 26 on the plate 18. The shaft 38 which carries the star wheel 40 and the wiper element 44 is journalled in the cover plate 68 the contacts 52 being positioned above the star wheel 40. The flow of hydraulic fluid displaced from a working cylinder 62 behind a piston, not shown, and passing through a dependent tube engaged within an upstanding tube 70 leading to the valve chamber is restricted by the valve 10 which is adjusted according to the setting of the wiper 46 of the switch 48. The application of the invention to lever type shock absorbers is also described. In a modification, Fig. 1, of the second Provisional Specification a rotary control switch 200 has equiangularly-spaced fixed contacts 204 and a rotor 206 which is movable from one rest position to another between the contacts 204 with a snapaction to make with its wiper 208 only a momentary connection with an intervening contact 204. The contacts 204 are connected to the stationary contacts 216 of a second rotary switch 218 which has a rotor 221 with radial wipers 222 adapted to engage successive contacts 216 and which is carried by the shaft 38. The switch 218 has a common contact 224 which is in permanent sliding engagement with the rotor 220 and which is connected to one end of a solenoid 226 of a rotary stepping mechanism, not shown, the other end of the solenoid being connected to earth. When the setting of the shock absorber adjustment is to be changed the rotor 206 of the switch 200 is rotated past the respective stationary contact 204 between the two rest positions so that the solenoid is momentarily connected to the battery 214 by way of the corresponding stationary contact 216 the rotor 220, and the contact 224 of the switch to operate the stepping mechanism and also rotate the rotor 220 so that the wiper 222 moves to the next contact 216. In the shock absorber, Fig. 2, the solenoid 226 and the stepping mechanism are arranged in a housing 228, the needle valve 10 being replaced by a rotatable sleeve valve 252 having a number of radial ports 258 of different diameter which selectively co-operate with the upstanding sleeve 246. The arrangement is also applicable to lever-type shock-absorbers.