GB2328264A

GB2328264A - Vibration damper

Info

Publication number: GB2328264A
Application number: GB9817413A
Authority: GB
Inventors: Claus Krakofczik; Stefan Koenig
Original assignee: Carl Freudenberg KG
Current assignee: Carl Freudenberg KG
Priority date: 1997-08-16
Filing date: 1998-08-10
Publication date: 1999-02-17
Anticipated expiration: 2018-08-10
Also published as: GB2328264B; DE19735524A1; GB9817413D0

Abstract

A vibration damper comprises an inertia mass (1) which is connected to at least one spring body (2). The spring body (2) consists of a metallic material and is formed integrally and of a common material with the inertia mass (1).

Description

2328264 - 1 VIBRATION DAMPER The invention relates to a vibration damper,

comprising an inertia mass which is connected to at least one spring body.

Vibration dampers of this type are generally known, the spring body consisting of an elastomer material and being vulcanized with the inertia mass which preferably consists of a metallic material. Components of this type are suitable for damping vibrations in a low frequency range of up to 400 Hz.

The previously known vibration dampers are not suitable for damping vibrations in a frequency range of up to about 2 kHz, because the spring body made of an elastomer material brings about excessive damping of the vibrations.

It is an object of the invention to develop a vibration damper of the previously known type in such a way that it has very good properties of use in a frequency range of up to about 2 kHz.

Accordingly, the present invention provides a vibration damper, comprising an inertia mass which is connected to at least one spring body, wherein the spring body consists of a metallic material and is formed integrally and of a common material with the inertia mass. on account of the material, the spring body exhibits only very slight damping, so that it is suitable to damp vibrations of higher frequency in the range of up to about 2 kHz in an excellent manner.

The resonance frequency of the vibration damper is determined via the geometric dimensions of the spring, such as its height and its diameter. Moreover, the inertia mass is of great importance in determining the resonance frequency.

During the intended use, the vibration damper oscillates with oscillation behaviour which is characterized by the parameters mass, spring resilience and damping. The mass of 2 the vibration damper itself is a rigid body.

In this case, the inertia mass oscillates out-of -phase in relation to the vibrations of higher frequency introduced.

According to an advantageous refinement, the spring body is arranged on an essentially plate-shaped holder which is formed integrally and of a common material with the spring body. By virtue of the fact that the inertia mass, the spring body and the holder are formed merging integrally into one another and are of a common material, the vibration damper according to the invention including the holder comprises only one component and can be produced in a simple and costeffective manner. The integral design results in assembly errors being reduced to a minimum. The vibration damper according to the invention can be produced, for example, by machining, i.e. by turning. Production by moulding, for example casting, is also possible.

The unit, comprising the damper mass, spring body and holder, preferably has an essentially double T-shaped cross section. In order to permit a high resonance frequency of the vibration damper in the range of about 2 kHz, it is of great importance that the operational parts from which the vibration damper is made are arranged in a rigid and relatively immobile manner relative to one another, which is ensured by the integral design. Moreover, it is necessary for the attachment of the vibration damper to the vibrating machine element likewise to be of very rigid design in order to achieve a direct and precise transmission of the vibrations from the machine element to the vibration damper and thus efficient vibration damping. It is possible, for example, to provide a cutout in the machine element, the shape of which cutout is congruent with the holder, the holder being pressed and/or glued into the cutout.

The spring body is preferably of rod-shaped design and is preferably arranged concentrically relative to the holder - 3 and the inertia mass. The geometric dimensions of a rodshaped spring body can be adapted in a particularly simple manner to the respective circumstances of the application, for example by changing its diameter.

For applications in which vibration dampers with greater damping are required, it has proved to be advantageous for the spring body to be surrounded on the outer circumference by a damping ring which is made of polymeric material and is arranged with axial prestress between the inertia mass and the holder. In addition and/or as an alternative, it is possible for the damping ring to surround the spring body with radial prestress.

The use and arrangement of the damping ring result in the resonance frequency rising and the excess resonance propagating. The use of the damping ring enables the sharp narrow-band excess resonance to be influenced in the following manner. The damper with a damping ring has a higher level of total damping. In technical terms, this means that the previously narrow-band excess resonance propagates and reduces in terms of its amount. The damping ring also has a resilience which causes the resonance frequency to rise. For example, the resonance frequency of the vibration damper without a damping ring is about 1. 8 kHz, in contrast with a damping ring 2. 1 kHz.

By means of the comparatively broad-band vibration damping, the vibration damper according to the invention can be used in a versatile manner in the higher-frequency range and thus covers scatter of the resonance to be damped in standard parts.

According to a refinement, provision may be made for the inertia mass to be penetrated by a first opening and the spring body by a second opening in each case centrally, for the openings to be arranged concentrically relative to one another, for a tensioning element to be arranged in the second 4 - opening, which element touches the wall bounding the second opening, for an actuator to be arranged in the first opening, and for the tensioning element to be widenable by means of the actuator and to be able to be pressed with variable prestress against the wall. The tensioning element preferably consists of a polymeric material or a soft metal, such as for example aluminium, the actuator being formed by a screw guided in the inertia mass. By virtue of a design of this type, the resonance frequency of the vibration damper can be adjusted by changing the properties of use of the spring. With an increasing prestress of the actuator on the tensioning element, the spring hardens and the resonance frequency rises. Such a design is particularly advantageous when the vibration damper has to be adapted to the respective circumstances of the application. If the vibration damper is just off the resonance to be damped, for example for reasons of production, it can be adjusted precisely by means of the actuator and the tensioning element.

The inertia mass, the spring body and the holder are preferably designed to be rotationally symmetrical. In this case, it is advantageous that rotationally symmetrical components can be produced, for example by turning, in a simple and cost-effective manner.

The invention will now be described in greater detail by way of example only with reference to the accompanying drawings, in which Figures 1 to 3 are sectional and diagrammatic views of three exemplary embodiments of the vibration damper according to the invention.

Figures 1 to 3 show three embodiments of vibration damper, in which the spring body 2 consists of a metallic material and is formed integrally and of a common material with the inertia mass 1. The embodiments shown here are each designed to be rotationally symmetrical, the damper mass 1 the spring body 2 and the holder 3 forming an integrally 35 produced unit which consists of only one metallic material, for example steel or aluminium.

Figure 1 shows the simplest form of the vibration damper according to the invention. The inertia mass 1, the spring body 2 and the holder 3 are each formed by solid cylinders 5 which are arranged concentrically relative to one another. Vibration dampers of this type may, for example, be cast or turned from a cylindrical rod material.

Figure 2 shows a second exemplary embodiment which differs from the first exemplary embodiment from Figure 1 in the fact that the spring body 2 is surrounded by a damping ring 4. In this embodiment, the damping ring 4 consists of a polymeric material which surrounds the spring with radial prestress along its total axial extent and is braced in the axial direction with prestress between the inertia mass 1 and the holder 3.

Figure 3 shows an embodiment of the vibration damper, in which the resonance frequency can be adjusted by an actuator 9 which acts via a tensioning element 7 on the spring body 2. In this embodiment also, the inertia mass 1, the spring body 2 and the holder 3 are arranged concentrically relative to one another. The inertia mass 1 is provided with a first opening 5, the wall bounding the first opening 5 being provided with a screw-thread to receive the actuator 9 designed as a screw 10. The spring body 2 is also penetrated centrally by an opening 6, there being arranged, within this second opening 6, a tensioning element 7 which consists of a polymeric material or a soft metallic material, is of cylindrical shape and contacts the wall 8 bounding the second opening, resting against it with elastic prestress. If, for example, the resonance frequency of the vibration damper is to be increased, it is necessary for the spring to have greater spring rigidity, which means that the spring must become harder. For this purpose, the screw 10 is screwed in the direction of the tensioning element 7 until the tensioning element 7 touches the wall 8 bounding the second opening 6, 6 resting against it with the correct prestress. The tensioning element 7 can be widened in the radial direction by the actuator 9.

Each of the vibration dampers described above has 5 excellent properties of use within a frequency range of 1 to 2 kHz throughout a long service life. By virtue of the fact that no elastomer materials are used in the vibration damper according to the invention, the properties of use remain unchanged throughout a very long service life.

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Claims

1. A vibration damper, comprising an inertia mass which is connected to at least one spring body, wherein the spring body consists of a metallic material and is formed integrally and of a common material with the inertia mass.

2. A vibration damper according to claim 1, wherein the spring body is arranged on an essentially plate-shaped holder which is formed integrally and of a common material with the spring body.

3. A vibration damper according to claim 2, wherein the unit, comprising the damper mass, spring body and holder, has an essentially double T-shaped cross-section.

4. A vibration damper according to claim 2 or 3, wherein the spring body is surrounded on its outer circumference by a damping ring which is made of a polymeric material and is arranged with axial prestress between the inertia mass and the holder.

5. A vibration damper according to claim 2, 3 or 4, wherein the inertia mass, the spring body and the holder are rotationally symmetrical.

6. A vibration damper according to any preceding claim, wherein the spring body is of rod-shaped design.

7. A vibration damper according to any preceding claim, wherein the inertia mass is penetrated by a first opening and the spring body by a second opening, in each case centrally, the openings are arranged concentrically relative to one another, there is arranged in the second opening a tensioning element which touches the wall bounding the second opening, an actuator is arranged in the first opening and the tensioning element can be widened by the actuator and can be pressed with variable prestress against the wall.

8 8. A vibration damper according to claim 7, wherein the tensioning element consists of a polymeric material, and the actuator is formed by a screw guided in the inertia mass.

9. A vibration damper, substantially as described herein with reference to Figure 1, 2 or 3 of the accompanying drawings.