Brakes – Internal-resistance motion retarder – Controlled by an operator remote from retarder
Patent
1992-12-28
1994-06-07
Oberleitner, Robert J.
Brakes
Internal-resistance motion retarder
Controlled by an operator remote from retarder
18832217, 188315, 188318, F16F 950
Patent
active
053181573
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to a hydraulic shock absorber for a motor vehicle and, more particularly, to a shock absorber of this type which comprises means making it possible to pilot-operate the damping obtained in accordance with predetermined laws.
A hydraulic shock absorber conventionally comprises a working cylinder and a piston integral with a rod which projects from one end of the cylinder. The piston divides the cylinder into two chambers filled with a damping liquid. The piston and the cylinder are integral with the chassis of a motor vehicle and with a support of a wheel of this vehicle, respectively. Valves are incorporated in the piston and at the bottom of the cylinder in order selectively to put chambers of the cylinder in communication with each other and with an outer damping-liquid reservoir, which is generally disposed concentrically to the working cylinder, the shock absorber then assuming a "twin-tube" structure.
When the vehicle moves, the irregularities of the surface of the road then apply forces to each wheel which are transmitted to the shock absorber and which subject the damping liquid to compressive forces followed by pressure-reducing forces. Suitable calibrations of the valves mounted in the piston and in the bottom of the cylinder make it possible to adjust the level of absorption of these forces by the shock absorber, in accordance with a predetermined, but fixed, damping law.
In order to make it possible to adapt the flexibility (or "firmness") of the suspension of the vehicle, on the one hand, to certain characteristics of the irregularities of the surface of the road encountered by a wheel and, on the other hand, to the flexibility desired by the driver, corresponding for example to a "sporty" or "comfortable" drive, shock absorbers improved by the addition of a solenoid valve are known which make it possible to control the flow rate or the pressure drop of the damping liquid which passes from one chamber of the cylinder into the reservoir, or vice versa, or from one chamber into the other, in conjunction with the displacements of liquid permitted by the above mentioned S valves. It is then possible to adjust, by means of an electronic calculator controlling the solenoid valve, the flexibility of the suspension as a function of various piston, vertical acceleration of the body of the vehicle, speed of the vehicle, etc.--in such a way as to optimise the absorption of the movements of the body of the vehicle as a function of the irregularities of the surface of the road which are encountered by a wheel of the vehicle and/or of the type of flexibility of the suspension selected by the driver.
The document FR-A-2,588,343 discloses such a shock absorber in which the solenoid valve projects laterally from the working cylinder, this shock absorber thereby lacking any compactness. In other structures of known shock absorbers, the solenoid valve is integrated with the piston, with the rod of the piston or with the bottom of the working cylinder, and these structures therefore do not have this disadvantage. On the other hand, they demand major modifications of the Conventional components of the shock absorber, which are costly to implement. These modifications may additionally affect the mechanical strength of the shock absorber, which, consequently, makes it necessary to reinforce the modified components. Thus, for example, when the solenoid valve is incorporated in the rod of the piston, it is necessary to reinforce the diameter of the rod in order to compensate for the recess made in order to accommodate the solenoid valve. Furthermore, this increased diameter reduces the useful volume of the chamber of the cylinder which is traversed by the rod of the piston. In another structure of shock absorber, disclosed in U.S. Pat. No. 3,528,531, a manually rotatable valve is arranged in an end piece closing the upper chamber and traversed by the piston rod. However, such a valve requires to be adjusted that the shock absorber is disconnected from the vehicle to fully extend the rod fo
REFERENCES:
patent: 3528531 (1970-09-01), Schweller et al.
patent: 3843107 (1974-10-01), Atkins
patent: 4589528 (1986-05-01), Axthammer et al.
patent: 4749069 (1988-06-01), Knecht et al.
patent: 5148895 (1992-09-01), Kakizaki
Greenberg Laurence A.
Lerner Herbert L.
Oberleitner Robert J.
Siemens Aktiengesellschaft
Young Lee W.
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