Patent GB-1002946-A (GB)
Title: A valve device of an oil damper for suspension of a wheel of a vehicle
Inventor: MURATA YOSHIRO
IPC: F16F9/34
Filed: 1963-08-16
Abstract: 1,002,946. Hydraulic shock-absorbers. KAYABA INDUSTRY CO. Ltd. Aug. 16, 1963, No. 32555/63. Heading F2S. A valve device for an hydraulic damper adapted to be fitted to a wheel suspension system senses the rate of pressure rise in the working cylinder of the damper to enlarge and reduce the passage area communicating a high pressure to a low pressure side of the valve if the pressure rate is correspondingly larger or smaller than a predetermined valve so that high frequency vibrations in the unsprung weight of the suspension system are not transmitted to the sprung weight. As shown in Fig. 1, the outer rim of an annular disc valve 6 rests upon a seating above openings 5 in the base 4 of a foot valve fitted to the lower end of a working cylinder 3 the inner circumference of the valve 6 co-operating with a seating at the inner edge of an annular chamber 24 beneath a series of bores 25 in a radial flange of a valve member 7. The latter is urged downward by a spring 27 located between the radial flange of the valve body 7 and a guide 26 connected to the base 4. During a compression stroke of the shock absorber superior hydraulic pressure in an upper chamber A first urges the valve body downward so that the outer rim of the chamber 24 seats upon the disc valve 6 the inner periphery of which is pressed down by the valve body 7 to deform the disc 6 into a dish shape, further rise in pressure causing the disc 6 to flex away from its inner seat to provide a passage for the flow of fluid from the upper pressure chamber A to a lower pressure chamber B. During expansion of the damper the valve body 7 moves upward against the action of the spring 27 the outer rim of the disc valve 6 lifting to provide a relatively large flow area. A frequency responsive valve, which remains open for relatively high vibration frequencies and which progressively closes as the frequency of vibrations decreases so that normal damping through the disc valve 6 obtains, comprises a piston 10 and a hollow rod 20 which sealingly slide respectively in a cylinder 8 and a boss 9 of the valve body 7 to provide a closed oil chamber 12, bores 14 leading to an annular chamber 13 in the piston 10 being closed by a plate valve 15 which is urged upward by a spring 26 and is provided with orifices 16. A wide passage 20, leading through the piston 10 and rod 11 from the chamber A, has parts 21 which, in the raised position of the piston 10, determined by a stop ring 19, communicate through a corresponding annular chamber 22 and ports 23 in the valve body boss 9 with the chamber B. Leakage of fluid through the ports 16 in the valve plate 15 is slow enough to prevent high frequency oscillations of the valve 10, 11 in sympathy with corresponding fluid pressure variations so that the ports 21, 23 fully register and corresponding bumps are not transmitted through the damper to the spring mass. Leakage of fluid from the chamber 12 in the body 7 through the ports 16 is large enough during pressure variations of lower frequency so that the valve 10, 11 can descend and cut off the fluid passage 20, 21, 22, 23, normal suspension damping then taking place entirely through operation of the valve 6. A similar construction for a piston is also described.