VIBRATION ABSORBING DEVICE WITH A WEIGHTED MEMBRANE ANO FLUID DISPLACEMENT

Abstract

Vibration absorbing device comprising a housing (12), a membrane (14) enclosed in the housing (12) and thus forming two chambers (18a, 18b) in the housing (12), said chambers (18a, 18b) being filled with a fluid, at least one weight (16), arranged on the membrane (14) in order that a movement of the weight (16) causes a movement of the membrane (14), and at least one duct (24) arranged to permit the fluid to flow between the two chambers (18a, 18b) if the membrane (14) and the weight (16) move.

Claims

1. A vibration absorbing device comprising: a housing, a membrane enclosed in the housing and thus forming two chambers in the housing, said chambers being filled with a fluid, at least one weight arranged on the membrane so that a movement of the weight causes a movement of the membrane, and at least one duct configured to permit the fluid to flow between the two chambers if the membrane and the weight move.

2. The vibration absorbing device as claimed in claim 1, wherein the membrane is produced from a material selected from the group consisting of: aluminum, steel, a high temperature nickel-chromium alloy.

3. The vibration absorbing device as claimed in any claim 1, wherein the weight comprises a duct to permit the fluid to flow between the two chambers.

4. The vibration absorbing device as claimed in claim 3, wherein said duct of the weight is pierced in the center of the weight.

5. The vibration absorbing device as claimed in claim 1, wherein the membrane comprises a duct to permit the fluid to flow between the two chambers.

6. The vibration absorbing device as claimed in claim 1, wherein the fluid is air.

7. The vibration absorbing device as claimed in claim 1, wherein the weight is arranged at the center of the membrane.

8. The vibration absorbing device as claimed in claim 1, wherein the diameter of at least one duct is between 1% and 10% of a main length of the membrane.

9. A component which may be subjected to vibrations, it comprise a vibration absorbing device configured to at least partially absorb the vibrations to which the component is subjected, the device comprising: a housing, a membrane enclosed in the housing and thus forming two chambers in the housing, said chambers being filled with a fluid, at least one weight arranged on the membrane so that a movement of the weight causes a movement of the membrane, and at least one duct configured to permit the fluid to flow between the two chambers if the membrane and the weight move.

Description

LIST OF FIGURES

[0052] Other aims, features and advantages of the invention will become apparent upon reading the following description given solely by way of non-limiting example and which makes reference to the attached figures in which:

[0053] FIG. 1 is a schematic view of a vibration absorbing device in accordance with one embodiment of the invention.

[0054] FIG. 2 is a schematic view of a vibration absorbing device in accordance with one embodiment of the invention.

[0055] FIG. 3 is a diagram modelling the mechanical behavior of a component protected by a vibration absorbing device in accordance with one embodiment of the invention.

DETAILED DESCRIPTION OF AN EMBODIMENT OF THE INVENTION

[0056] In the figures, for the sake of illustration and clarity, scales and proportions have not been strictly respected.

[0057] Furthermore, identical, similar or analogous elements are designated by the same reference signs in all the figures.

[0058] FIGS. 1 and 2 schematically illustrate the basic principle of a vibration absorbing device 10 in accordance with one embodiment of the invention, in a lateral cross-sectional view and perspective cross-sectional view respectively.

[0059] The vibration absorbing device 10 comprises a housing 12, a membrane 14 and a weight 16.

[0060] The membrane 14 is enclosed in the housing 12 and thus forms two chambers, a first chamber referred to as upper chamber 18a, and a second chamber referred to as lower chamber 18b. The terms “upper” and “lower” are used only for illustrative purposes in reference to the cross-sectional view of FIG. 1 and in no way restrict the orientation of the vibration absorbing device on the component.

[0061] The membrane 14 is circular in this embodiment and can also be of other shapes in other embodiments, e.g. rectangular, square, etc. In particular, the membrane takes the shape of the housing so as to form the two chambers in the housing no matter the shape of the housing.

[0062] The membrane 14 is preferably of a constant and isotropic thickness. For example, the membrane is produced from one of the following materials: aluminum, steel, Inconel®, in particular Inconel X750®.

[0063] The housing 12 is configured to be fixed to a component 20 so as to absorb the vibrations to which the component 20 is subjected. In order to do this, the housing 12 comprises a point of attachment 22.

[0064] The absorption of the vibrations by the vibration absorbing device 10 is effected by virtue of the setting in motion of the membrane 14 and the weight 16, which create a resonance instability in order to capture the vibration energy. The weight 16 is arranged on the membrane, preferably close to the center of the membrane or at the center of the membrane.

[0065] The movements of the membrane 14 and of the weight 16 cause over-pressure in one of the chambers and negative pressure in the other chamber. Some of the fluid contained in the over-pressure chamber is thus displaced towards the negative pressure chamber by flowing through at least one duct 24. The displacement of the fluid in the duct 24 permits the dissipation of the energy by the fluid brushing against the wall of the duct 24.

[0066] In this embodiment, the duct 24 is pierced in the weight in order to save space. In other embodiments, the duct may extend outside the housing so as to connect the two chambers. The duct is configured to place the two chambers in fluid communication.

[0067] In FIG. 1, the weight 16 is illustrated in an at-rest position, with no vibrations present.

[0068] In FIG. 2, the weight 16 is illustrated out of its at-rest position, and the membrane 14 is deformed, following the capture of the vibration energy, with respect to the dotted line 114 representing the position of the membrane 14 at rest. In this configuration, the upper chamber 18a is in a state of over-pressure and the lower chamber 18b is in a state of negative pressure, which causes the fluid to flow from the upper chamber 18a to the lower chamber 18b. By reason of the amount of energy captured around the linear resonance frequency, the flow of the fluid can reach high speeds, e.g. 0.8 Mach for air, which causes a strong dissipation of energy owing to the drag of the air and the friction on the walls of the duct.

[0069] FIG. 3 schematically illustrates a model of the mechanical behavior of a component protected by a vibration absorbing device in accordance with one embodiment of the invention.

[0070] The component is illustrated by a mass m1, connected to another element, e.g. a chassis 300, by a spring with a stiffness k1 and a damper with a damping level c1. The spring and the damper are models of the mechanical behavior of the connection between the component and the chassis and in no way assume the physical reality of the components forming this connection, which may vary in nature and is not stipulated here.

[0071] The weight and the membrane of the vibration absorbing device are represented by a mass m2, connected to the component by a spring with a stiffness k2 and a damper with a damping level c2. For the most part, the stiffness k2 is made up of the stiffness of the membrane and the stiffness of the air compressed by the membrane in the two chambers upon displacement of the weight and of the membrane. The damping level c2 results from the flow of the fluid between the two chambers via the duct, the membrane having no, or very little, self-damping.

[0072] The invention is not limited to the embodiments described above. In particular, the dimensions of the device, the shape of the housing, the dimensions and the thickness of the membrane, the dimensions and the mass of the weight, etc. can vary in order to be adapted to the component to be protected, to the maximum size which the device must not exceed, to the configuration of the component and of the device in the vehicle on which they are mounted, etc.