Brakes – Internal-resistance motion retarder – Valve structure or location
Patent
1998-12-21
2000-09-19
Oberleitner, Robert J.
Brakes
Internal-resistance motion retarder
Valve structure or location
16 49, 16 66, 18832217, 188317, F16F 934
Patent
active
061198323
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention concerns a pneumatic movement damper with a cylinder which is closed on one side, with a piston which slides within the latter and which is connected to a piston rod, with a packing mounted on the piston and with a throttle passage provided on the piston for connecting the two cylinder spaces separated by the piston and the packing.
BACKGROUND OF THE INVENTION
Pneumatic dampers of this type (DE 296 00 438 U1) are frequently used for slowing down the movement of a flap which can swing open, for example the flap of a glove compartment in a motor vehicle. Flaps of this type nowadays are generally very heavy and formed in such a way that a part of the contents of the glove compartment is also situated in said flaps. When the glove compartment lock is undone, the flap falls into the open position with the force of gravity. In order that the flap does not suddenly swing down and fall on the passenger's legs, the pneumatic movement damper should slow down the movement when the flap is opened. However, when the flap is being closed, the movement damper should reciprocally impede the closing movement as little as possible.
The known movement damper of the type mentioned above has an axial boring provided as a throttle passage in the piston. When the piston is retracted from the cylinder the packing forms a seal with the cylinder wall and air alone should pass through this throttle boring. In order to achieve an adequate damping effect, the throttle boring should have a diameter of only circa 0.1 mm. When the piston is produced from plastic material difficulties are presented in producing such a fine boring. This can generally only be achieved by a laser beam for which purpose a separate work process is required which increases production costs. The fine boring can also lead to defective functioning or even failure of the movement damper. Namely, dirt particles can be deposited in front of the boring or even in the boring causing the boring to be partly or totally blocked. In the former case then, the opening movement of the flap occurs too slowly. In the latter case, the flap can no longer be dropped down at all. While closing the flap the piston is pushed into the cylinder. Hereby, a pressure cushion would build up in the cylinder space located between the cylinder base and the piston. In order that this does not occur, the packing is formed elastically so that it can be raised from the cylinder wall and air can then pass through the annular gap which is thus formed. However, experience has shown that such elastic packings made of plastic material lead to a jerky movement even when the cylinder is formed from plastic material.
Thus, the object underlying the invention is to create a pneumatic movement damper of the type mentioned at the beginning which can be easily produced and which is operationally reliable.
SUMMARY OF THE INVENTION
This is achieved according to the invention in that the piston has a conical seat widening out from the piston rod and a flange part adjacent to the largest diameter of the conical seat. The packing has a truncated recess corresponding to the conical seat and can move within limits in the axial direction between the flange part and an annular flange arranged on the piston rod at an axial distance from the flange part. Radial grooves are provided in the surfaces of the flange part and the annular flange, the surfaces extending perpendicular to the axis of the cylinder and oriented towards the packing, and the groove provided in the flange part having a smaller cross-section than the groove arranged in the annular flange and the former forming the throttle passage. A flow passage is provided between the conical seat and the recess.
In the movement damper according to the invention, the packing can move in a limited fashion relative to the piston. When the piston rod is retracted out of the cylinder, the front surface forms a tight seal against the flange part and the air passing through the flow passage between the conical seat and the reces
REFERENCES:
patent: 3059269 (1962-10-01), Selinger et al.
patent: 3083399 (1963-04-01), Moran et al.
patent: 3555591 (1971-01-01), Sogoian
patent: 3937450 (1976-02-01), Bauer
patent: 4877226 (1989-10-01), Taylor
patent: 5157806 (1992-10-01), Wartian
patent: 5471708 (1995-12-01), Lynch
Hoerauf & Kohler Verwaltungs KG
Oberleitner Robert J.
Talavera Melanie
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