Rotary damper

Details Rotary damper Rotary damper

1998-10-13

2001-01-16

Oberleitner, Robert J. (Department: 3613)

Brakes

Internal-resistance motion retarder

Having a thrust member with a variable volume chamber

C188S293000, C188S296000

Reexamination Certificate

active

06173822

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a rotary damper, in particular for the actuation of a part in motor vehicles.
BACKGROUND OF THE INVENTION
From DE 42 44 484 there has become known a rotary damper with which in a damping chamber which contains a viscous medium there is arranged a vane which is mounted upon shaft. With a rotation of the shaft the medium is displaced and flows between the end of the vane and the chamber wall. With the known rotary damper the vane is inclined towards one side in the circumferential direction and is deformable or bendable relative to the shaft in a manner such that it is pivoted towards the cylindrical chamber wall when the shaft undergoes rotation in the inclination direction is pivoted towards the shaft when shaft undergoes rotation in the opposite direction. By means of this structure a rotary damper is provided which in opposite rotational directions creates a damping effect of differing strength. With a pivoting of the vane in the direction of the chamber wall, the gap defined with respect to the wall is reduced so that a relatively high braking force is developed. If the shaft however is rotated in the opposite direction, the vane pivots in the direction of the shaft so that the distance of the vane to the cylindrical chamber wall is enlarged. By means of this structure a larger flow cross section is provided, and the rotational force in this direction is braked much less. As a result with such a rotary damper a type of free-running is created.
There are cases in which the braked movement of an actuated part is often not sufficient to prevent damage, for example with back rests or the like.
OBJECT OF THE INVENTION
It is therefore the object of the present invention to provide a rotary damper in particular for an actuation part in motor vehicles which prevents a braking deceleration or the amount of breaking action from exceeding a predetermined value.
With the rotational damper according to the present invention in the damping chamber there is arranged a locking cam which extends radially inwards and with which the free end of the vane comes into engagement when the vane is pivoted a predetermined amount towards the chamber wall. A pivoting of the vane towards the chamber wall is dependent on the torque or the acceleration of the rotor (the shaft plus the vane). If the acceleration reaches a certain value which possibly is critical for the actuation of the part to be actuated, the vane comes into engagement with the locking cam so that any further movement is completely blocked. As soon as the deceleration or braking action is zero the vane may retract from the part locking cam and as a result is again released. The movement of the part to be actuated may as a result be continued.
It is to be understood that with several vanes to each one there may be allocated a locking cam. Also a number of locking cams may be provided which is a multiple of the number of vanes. This is advantageous when a very rapid stop is to be obtained on reaching the predetermined acceleration.
In one embodiment of the present invention it is provided that on one side of the vane a support rib or likewise is mounted on the shaft in such a manner that the vane bears against the support rib when it is pivoted towards the chamber wall by a predetermined amount. The support rib has the object of preventing the vane from being bent through and at the same time rattling past the locking cam. The rib thus fulfills the object of preventing a rotation beyond the locking position.


REFERENCES:
patent: 3709335 (1973-01-01), Carlsson et al.
patent: 4666386 (1987-05-01), Winkler et al.
patent: 5277282 (1994-01-01), Umemura
patent: 5449054 (1995-09-01), Carlsson et al.
patent: 1 506 108 (1969-06-01), None
patent: 196 15 208 (1986-10-01), None
patent: 42 44 484 (1992-07-01), None
patent: 195 48 921 (1996-07-01), None
patent: 6-280918 (1994-07-01), None

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