Spring devices – Resilient shock or vibration absorber – Including energy absorbing means or feature
Reexamination Certificate
2001-01-11
2001-10-30
Schwartz, Christopher P. (Department: 3613)
Spring devices
Resilient shock or vibration absorber
Including energy absorbing means or feature
C267S140140
Reexamination Certificate
active
06308942
ABSTRACT:
FIELD OF THE INVENTION
The present invention pertains to a two-chamber step bearing with hydraulic damping especially for mounting engines of motor vehicles, which has at least one fluid-filled working chamber and at least one compensating chamber connected to same by a nozzle channel of variable cross section.
BACKGROUND OF THE INVENTION
An engine bearing of this type has been known from, e.g., DE 36 14 161. In the two-chamber step bearing disclosed in this document, the working chamber and the compensating chamber are provided with walls consisting of ring-shaped rubber membranes, which have a predetermined buckling characteristic adapted to the operating load.
The compensating chamber and the working chamber are connected to one another by a nozzle chamber, whose walls are formed by corresponding profiles overlapping one another in two rigid components adjustable in relation to one another, wherein the two components are axially adjustable in relation to one another by means of a screwable adjusting member, which is mounted coaxially to the principal axis of the bearing and is fixed in the axial direction in the bearing housing of the two-chamber step bearing and can be actuated by means of a component projecting from the housing.
The adjustment of the nozzle channel cross section is performed by means of a spindle, which is mounted freely rotatably in the bearing housing, wherein one of the two components forming the nozzle channel is in threaded engagement with the spindle for the axial adjustment, so that a reduction or enlargement of the nozzle channel cross section can be brought about by rotating the spindle.
Even though a certain adjustment of the two-chamber step bearing to the design requirements of the engine, whose vibrations are to be damped by the bearing, is possible due to the exclusively manual adjustability of the two-chamber step bearing by means of the component projecting from the housing, adjustment during the running operation is ruled out because of the existing installation conditions.
Moreover, an additional stiffness of the fluid cushion in the working chamber, which is desirable because of different operating states, is not possible in the two-chamber step bearing disclosed in the above-mentioned document. However, precisely the combination of influencing both the nozzle cross section and the damping capacity of the hydraulic cushion within the working chamber would make possible a much better adaptation of the two-chamber step bearing to the different operating conditions of the engines to be mounted within motor vehicles. Such an adaptation is required especially in the case of the use of direct injection diesel engines, which are frequently used now, and whose vibration characteristics are determined by different vibration characteristics at idle and during travel with different vibration frequencies far more greatly than in the case of the gasoline and diesel engines that have been used hitherto.
In the two-chamber step bearing known from the state of the art, an increase in the channel cross section leads to an increase in the damping of the bearing, without a change in the frequency level or the dynamic stiffness of the bearing. This increase in damping is quite important for the elimination of low-frequency high-amplitude vibrations.
However, the additionally occurring high-frequency vibrations with small amplitudes can be effectively controlled only by changing the stiffness of the ring-shaped rubber membrane or of the fluid cushion cooperating with same.
SUMMARY AND OBJECTS OF THE INVENTION
The object ofthe present invention is therefore to improve a two-chamber step bearing of this type based on the state of the art such that a change in the damping characteristic is made possible during the operating state, where both low-frequency vibrations of large amplitude and vibrations of a higher frequency with a correspondingly lower amplitude are to be effectively damped.
Another object is to make the two-chamber step bearing of this type compact in terms of the mounting space and to guarantee reliable operation under all operating conditions.
This object is accomplished according to the present invention by the cross section of the nozzle channel being changed by means of a first motor-powered actuating drive and by the working chamber being provided with a buckling spring integrated in one of its walls, whose stiffness can be varied by means of a second motor-powered actuating drive that is independent from the first actuating drive.
This design according to the present invention makes it possible, for the first time ever, to rapidly and reliably adapt a two-chamber step bearing of this type to the different operating conditions of a motor vehicle. Both the occurring high-frequency vibrations with low amplitude and low-frequency vibrations of a correspondingly higher amplitude can be effectively eliminated by the use of the actuating drives and the resulting change in the damping characteristic of the two-chamber step bearing according to the present invention. Another essential advantage ofthe present invention is that, for the first time ever, both the nozzle cross section and at the same time the damping characteristic of the hydraulic cushion can be changed.
Another advantage arising in connection with the installation of such a two-chamber step bearing according to the present invention is that no additional special connections are to be provided besides electric supply lines for the actuating drives.
It has proved to be particularly expedient to arrange both actuating drives in the direction of the principal axis of the bearing coaxially one on top of another, wherein both actuating drives have actuating members designed as electric motor-driven threaded spindles. One of the threaded spindles is designed here as a hollow spindle provided with a central through hole, in the through hole of which the other threaded spindle is arranged. This design embodiment guarantees an especially space-saving design of the actuating drives and makes possible a completely independent simultaneous or separate control of both the nozzle channel cross section and the damping properties of the hydraulic cushion.
The use of electric stepping motors as actuating drives makes possible an especially sensitive change of the setting parameters, and no concessions need to the made in terms of the compactness of the design.
Another essential advantage of the present invention arises from the feature that the nozzle channel between the working channel and the compensating channel extends in a plane located at right angles to the principal axis ofthe bearing helically around the principal bearing axis. A gentle transition is guaranteed by this design between the channel inlet opening into the working chamber and the channel outlet opening into the compensating chamber, which makes possible the turbulence-free entry and discharge of the fluid, but is also advantageous especially for the service life of the closing membrane forming the lower closure of the working chamber and extending into the channel cross section.
An exemplary embodiment of the subject of the present invention will be explained in greater detail below on the basis of the attached drawings.
The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding ofthe invention, its operating advantages and specific objects attained by its uses, reference is made to the accompanying drawings and descriptive matter in which a preferred embodiment of the invention is illustrated.
REFERENCES:
patent: 5238232 (1993-08-01), Kobayashi et al.
patent: 5297781 (1994-03-01), Gennesseaux
patent: 5779231 (1998-07-01), Okazaki et al.
patent: 6059275 (2000-05-01), Muramatsu
Ersoy Metin
Jordens Ernst-Gunter
McGlew and Tuttle , P.C.
Schwartz Christopher P.
ZF Lemforder Metallwaren AG
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