Spring devices – Resilient shock or vibration absorber – Including energy absorbing means or feature
Reexamination Certificate
2000-01-21
2001-08-21
Oberleitner, Robert J. (Department: 3613)
Spring devices
Resilient shock or vibration absorber
Including energy absorbing means or feature
C267S219000
Reexamination Certificate
active
06276672
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to bearings, and more particularly to a dual-mode twin-chamber thrust bearing having hydraulic damping.
A dual-mode twin-chamber thrust bearing having hydraulic damping in particularly suited for use as an engine bearing in motor vehicles. The bearing has a working chamber and an equalizing chamber which are separated by a partition. The partition is provided with a passageway that can be closed by an actuator, and also has a damping channel that hydraulically links the two chambers. A membrane is located in a recess in the partition. The membrane effectively covers openings in the partition on both sides and can be sealingly positioned by the actuator.
Bearings of this type are used to damp both high-frequency, low-amplitude and low-frequency, high-amplitude vibrations. Higher-frequency vibrations that occur during vehicle operation are isolated by the membrane, which is arranged in a nozzle cage and becomes effective when the passageway in the center of the partition is closed. Low-frequency vibrations are suppressed by the damping channel. For example, in order to suppress low-frequency vibrations during idling, the passageway in the partition is opened and the liquid column present in the passageway acts as a damper for the vibrations.
U.S. Pat. No. 5,344,127, which is incorporated by reference, describes a dual-mode twin-chamber thrust bearing where the passageway located in the center of the partition can be closed using an actuator. The actuator is actuated by vacuum and keeps the passageway closed during operation, but the passageway is opened during idling. This embodiment has proven useful in many applications.
German Patent Application 198 07 868 represents an improvement with respect to the above-mentioned embodiment. In that patent, damping of vibrations caused by idling and isolation of higher-frequency vibrations in a speed range above idling speed is improved by the fact that the membrane can be sealingly positioned by the actuator when the passageway in the partition is opened. During operation of an engine above idling speed, the passageway is closed by the actuator during operation above the idling speed, and the seal created by the membrane positioned within the partition is removed by a restoring spring in the actuator. In this operating state, the bearing functions as a generally known hydraulically damping bearing, where the membrane is arranged so that it can move loosely back and forth within the partition in order to isolate high-frequency, low-amplitude vibrations induced by the engine. In order to damp low-frequency, high-amplitude engine vibrations during idling, the passageway is opened and the liquid present in the passageway vibrates back and forth with a phase shift. This reduces the rigidity of the bearing if there are idling vibrations.
Consistently outstanding results are achieved by using the dual-mode membrane. An elastically pre-tensioned tension element secures the position of the membrane when the passageway is open. As soon as the passageway is closed by the actuator, the membrane is released. To accomplish this, the adjusting spring has to overcome both the force required for closing the passageway and force of the tensioning element.
SUMMARY OF THE INVENTION
The object of the present invention is to further develop the thrust bearing in order to achieve further improvement in its operating and damping characteristics. Good vibration damping when the passageway in the center of the partition is securely closed and good isolation when the passageway is fully open should be achieved. The force required in opening to overcome the spring pre-tension of the closing spring should be as small as possible, since the available vacuum is limited. A pressure differential of 0.5 bar, maximum 0.7 bar, should not be exceeded. Finally, the use of a degressive closing spring should be possible.
In accordance with the above object, a dual-mode twin-chamber thrust bearing has a work chamber and an equalizing chamber. The chambers are separated by a partition. The partition has a passageway in the center that is closable via an actuator, and also has a damping channel that hydraulically connects the two chambers. The partition also has holes. A membrane is located in a recess in the partition. The membrane covers the holes in the partition and can be tightly sealed. An axially movable pressure disk secures or releases the membrane as it is pushed by the actuator. The pressure disk is provided with holes in the area of the partition holes.
The pressure disk can be displaced axially with almost no effort because it is provided with holes in the area of the partition opening. The pressure disk alternatively secures or releases the membrane when it is displaced by the actuator. The pressure disk is arranged next to the membrane in a gap formed between the top and the corresponding bottom of the partition so it can be freely displaced. Its displacement in either direction results in the membrane being either secured or released. The released membrane can be moved in either direction of the flow. The secured membrane rests firmly in contact with the bottom of the partition.
The pressure disk is provided with a hub-like connecting piece in the center, which is arranged in the passageway with its free edge pointing toward the equalizing chamber. This free edge of the connecting piece is used as a stop surface for closing the passageway. The mating surface of the seal is formed by an annular surface of the movable outer wall of the equalizing chamber.
Various embodiments of the actuator used to displace the pressure disk are conceivable. One preferred embodiment calls for the actuator to be arranged in the outer wall of the equalizing chamber and be provided with a catch. The catch protrudes into the connecting piece of the pressure disk and rests on the pressure disk. When the passageway has been opened by the actuator, the catch secures the membrane.
In order to achieve proper vibration damping, the catch may have a tulip shape. The bottom area of the tulip-shaped catch has lateral passageways, and the upper edge of the catch actuates the pressure disk. Alternatively, the catch can have a mushroom shape with a star-shaped cover. The points of the star contact the pressure disk to secure it in place.
The membrane is arranged in an annular groove of the partition bottom. It protrudes from the groove so that the pressure disk located immediately above it can perform the desired securing motion.
The pressure disk can be made of sheet metal coated with a polymeric material. The pressure disk can also be provided with sealing lips to seal the bottom of the damping channel.
It is advantageous if the openings in the pressure disk and those in the top and bottom of the partition are arranged flush to one another.
REFERENCES:
patent: 5029824 (1991-07-01), LaBleau et al.
patent: 5205545 (1993-04-01), Quast
patent: 5263693 (1993-11-01), Klein
patent: 5344127 (1994-09-01), Hettler et al.
patent: 5439204 (1995-08-01), Yamazoe et al.
patent: 5645138 (1997-07-01), Tajima et al.
patent: 5653427 (1997-08-01), Matsuda et al.
patent: 5833219 (1998-11-01), Mellon
patent: 5839720 (1998-11-01), Kojima
patent: 5848782 (1998-12-01), Hein et al.
patent: 6036183 (2000-03-01), Lee et al.
patent: 198 07 868 (1999-09-01), None
Rudolf Hans-Joachim
Weber Heinz
Firma Carl Freudenberg
Kenyon & Kenyon
Kramer Devon
Oberleitner Robert J.
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