Spring devices – Resilient shock or vibration absorber – Including energy absorbing means or feature
Reexamination Certificate
1999-04-15
2001-06-12
Oberleitner, Robert J (Department: 3613)
Spring devices
Resilient shock or vibration absorber
Including energy absorbing means or feature
C267S219000
Reexamination Certificate
active
06244578
ABSTRACT:
BACKGROUND INFORMATION
1. Field of the Invention
The invention relates to a switchable hydraulically damping mount.
2. Description of the Prior Art
A mount is known from German Patent 41 41 332 A1. The known mount is configured as a hydro-mount, the actuator being actuable by a pressure medium. The actuator is constituted by a piston which is associated, in gas-tight fashion and movably relative thereto, with a control pressure capsule that is arranged in the housing and can be acted on by pressure medium, the control pressure capsule being delimited by an at least partially elastically flexible first annular membrane which seals off the piston and the control pressure capsule with respect to the housing.
SUMMARY OF THE INVENTION
The object of the present invention is to develop a mount of in such a way as to prevent vibratory excitation of the actuator due to pressure elevations in the working space.
To achieve the objects of the invention, provision is made for the actuator to have, on the side facing the working space, a variable-volume gaseous medium-filled chamber that is connected to the atmosphere through at least one connecting opening. It is advantageous here that on the one hand high-frequency vibrations are effectively isolated, and other hand vibratory excitation of the actuator by pressure elevations in the working space is prevented. In addition, the gaseous medium-filled chamber prevents any rise in the dynamic spring stiffness, which would diminish noise insulation. The connecting opening to the atmosphere has the advantage that no pressure rise takes place in the chamber as the volume is reduced, so that the forces which oppose the forces that are introduced into the mount—and that, in the case of high-frequency vibrations, are naturally small—result only from the deformation stiffness of the chamber wall. It is thus possible, with a correspondingly flexible configuration of the chamber wall, for even the smallest forces introduced into the mount to be eliminated by way of a change in the chamber volume.
The actuator can be actuated by having positive pressure applied to it.
The chamber is delimited by at least one elastically flexible chamber wall configured in the manner of a membrane. High-frequency vibrations introduced into the mount, as well as pressure fluctuations in the working space resulting therefrom, are eliminated in outstanding fashion by the variable-volume chamber with its connecting opening to the atmosphere, while the introduced vibrations are not transferred to the actuator or the housing of the mount, so that the actuator cannot resonate.
The chamber wall is preferably arranged on the side facing toward the working space, and has the form of a corrugated diaphragm. Isolation of high-frequency vibrations is effected by way of the gaseous medium-filled chamber. Secondary contrivances, for example an annular membrane that is arranged inside the partition wall, are therefore superfluous for vibration isolation; as a result, the mount can be manufactured in particularly economical fashion, since no additional components are needed to form the gas-filled chamber.
The corrugated diaphragm is preferably delimited on its periphery by an annular film hinge that is joined to an upward convexity in a dome shape toward the working space. The corrugated diaphragm is configured as a bent spring, the film hinge having the function of a linkage. This guarantees outstanding back-and-forth movability of the upward convexity in the direction of the introduced vibrations.
The chamber can be arranged at least partially axially inside the orifice. It is advantageous here that the pressure fluctuations inside the working space resulting from the introduced vibrations act directly on the elastically flexible chamber wall configured in the manner of a membrane, and are isolated from it. Any transfer of vibrations to the adjusting piston—which also, like the chamber, constitutes a component of the adjusting apparatus that represents a spring-mass system, i.e. an elasticity—is reliably prevented by a configuration of this kind.
The actuator includes a closure plug made of elastomeric material and an adjusting piston, the chamber being enclosed and delimited by the closure plug and the adjusting piston. Any transfer of high-frequency vibrations from the working space to the adjusting piston is prevented by the fact that the gaseous medium-filled chamber, which is connected to the atmosphere through the connecting opening, is arranged between the adjusting piston and the working space. Precise switchability of the mount is thereby ensured, and no resonances, which might result in partial opening of the orifice and would thus negatively influence the damping system, can occur in the adjusting apparatus.
The closure plug can have, on the side facing toward the working space, a cup-shaped recess whose bottom boundary is constituted by the chamber wall. The circumferential boundary of the end face of the closure plug that is open toward the working space touches the partition wall sealingly under elastic preload when the orifice is closed. A further advantage of this embodiment is the fact that the axial movement of the adjusting piston toward the working space is damped by the comparatively high flow resistance of the recess. When the orifice is open, for example when the internal combustion engine supported by the mount is at idle, the mount has an outstanding canceling effect due to the cup-shaped recess.
In order to achieve a further improvement in the isolation of high-frequency vibrations, the partition wall can have an annular membrane that is displaceable in the direction of the introduced vibrations or is retained but deflectable, and that can be acted upon by damping fluid from the working space and equalization space, the chamber wall and the annular membrane being arranged in parallel in terms of functional engineering. The partition wall is preferably constituted by two circular rings which are associated in axial adjacency with one another, the annular membrane being arranged between the circular rings. In the region of the radial overlap of the circular rings and the annular membrane, the circular rings have grid-pattern holes to allow the higher-frequency vibrations to act on the annular membrane. The hydraulically effective surface for isolation of the higher-frequency vibrations is considerably enlarged by the parallel arrangement of the annular membrane and the chamber wall.
The closure plug and the adjusting piston are joined in nonpositive or positive fashion. The adjusting piston can have an annular projection, extending in the radial direction, that is arranged in a corresponding annular recess of the closure plug. The annular projection can, for example, be adhesively bonded into the annular recess.
Preferably, the closure plug and the adjusting piston are adhesively joined to one another by adhesive bonding. It is advantageous in this context that the join is absolutely sealed.
The adjusting piston is preferably made of a polymeric material. It is advantageous in this context that with this material, the adjusting piston is easy to manufacture and has a low mass. The inertia upon actuation of the adjusting piston is therefore low, resulting in exact switchability of the mount.
According to an advantageous embodiment, the orifice is arranged in the center of the partition wall, the orifice, when viewed in cross section, being conically enlarged axially in the direction of the equalization chamber. The advantage of the centrally arranged chamber lies in the fact that the vibrations, upon entering the working chamber, are eliminated over the shortest possible travel. This is particularly true if, according to a particular embodiment, the membrane of the chamber wall extends through the partition wall into the working chamber. As a result of the conical enlargement, when the adjusting apparatus is actuated, a gap of conical profile is formed, the cross section of which continuously increases until it is larger than the orifice inside the partition wal
Firma Carl Freudenberg
Kenyon & Kenyon
Oberleitner Robert J
Sy Mariano
LandOfFree
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