The present invention concerns a subassembly for the amplitude dependent absorption of shock, especially in a dashpot for a motor vehicle.
It is desirable in dashpots for motor vehicles in particular to prevent high-frequency and low-amplitude vibrations from being intercepted by the dashpot's shock-absorption mechanism itself. Such high-frequency vibrations can be initiated by the tread of the tire as it rolls over the roadway or by slight imbalances in the wheel. When such vibrations reach the overall shock-absorption mechanism, they can cause break-loose due to the stick-slip action of the piston on the mechanism's housing. The passengers will accordingly perceive disturbances in the suspension.
Several approaches to the solution of this problem have been proposed.
The elimination of resonance frequencies in motor vehicles by attaching the piston axially displaceable and spring-loaded to the end of the piston rod is known from U.S. Pat. No. 3,232,390 for example.
This solution, however, is complicated and cannot handle high frequency, low-amplitude vibrations in both directions.
The object of the present invention is accordingly a simple and reliable subassembly for the amplitude-dependent absorption of shock, a subassembly that takes up little additional space.
The main advantage of the present invention is its simplicity. Another is the little space it occupies in the housing. Finally, different components can be easily combined to attain different performance curves.
One embodiment of the present invention will now be specified with reference to the accompanying drawing, wherein
and
A piston 3 is accommodated in the housing 2 of the illustrated dashpot for motor vehicles and rests radially against its inner surface, partitioning the housing into two compartments 4 and 5. Piston 3 travels up and down inside the housing on the end of an oscillating piston rod 1. The compartments 4 and 5 are charged with fluid. As piston rod 1 displaces piston 3 up and down inside the housing, the fluid flows though the piston, attenuating the motion of the piston rod.
Piston 3 is provided with various fluid-conveying passages 6 and 7. One end of each passage 6 or 7 is, as illustrated in
The end of piston rod 1 that enters the housing is provided with a narrower extension 10 with a threaded section 11 at its lower end.
Piston 3 slides freely up and down over the narrower extension 10 of piston rod 1. Accommodated radially between the narrower extension 10 and the piston 3 in the illustrated example is a piston-rod centering sleeve 12 of preferably low-friction material. There is a motion-limiting gasket 13 and 14 at each end of piston-rod centering sleeve 12. Piston-rod centering sleeve 12 and motion-limiting gaskets 13 and 14 are axially secured over piston-rod extension 10 by a nut 15 that screws onto threaded section 11.
Piston 3 is accommodated along with its associated components (e.g. its cupsprings) in a carriage 16. Carriage 16 slides freely up and down, carrying the piston with it, whereas the cupsprings etc. are maintained therein subject to tension.
Accommodated axially between each motion-limiting gasket 13 and 14 and the face of piston 3 proximate thereto is a spring 17 and 18. As long as the pressures in compartments 4 and 5 are in equilibrium, springs 17 and 18 will maintain piston 3 halfway through the space it oscillates in, constituted by the bore through piston-rod centering sleeve 12. Furthermore, however, springs 17 and 18 resiliently limit the stroke of piston 3. These springs are depicted only schematically in
As illustrated in
Groove 19 acts as a bypass for ensuring an equal distribution of fluid between compartments 4 and 5. When the difference in pressure between the two compartments is only slight, the fluid will be allowed to flow through groove 19 with no motion on the part of piston 3 in relation to piston-rod centering sleeve 12.
The piston carriage 16 illustrated in
The piston carriage 16 illustrated in
The point of departure for the piston carriage 16 illustrated in
The springs 17 and 18 illustrated in
The embodiment illustrated in
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103 25 877 | Jun 2003 | DE | national |
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Number | Date | Country | |
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20040245058 A1 | Dec 2004 | US |