Brakes – Inertia of damping mass dissipates motion
Reexamination Certificate
2002-03-19
2003-07-29
Graham, Matthew C. (Department: 3683)
Brakes
Inertia of damping mass dissipates motion
Reexamination Certificate
active
06598718
ABSTRACT:
INCORPORATED BY REFERENCE
The disclosure of Japanese Patent Application No. 2001-099764 filed on Mar. 30, 2001 including the specification, drawings and abstract is incorporated herein by reference in its entirety.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a vibration damping device installed in a various kinds of vibrative members in order to reduce vibrations excited in these vibrative members, and more particularly to such a vibration damping device that is novel in construction and that is suitably applicable as a vibration damping device for use on an automotive vehicle for damping vibrations excited in suspension arms, sub flames, body panels, mounting brackets, and vibrative members used in an engine unit and an exhaustion system.
2. Description of the Related Art
As examples of vibration damping means for damping or reducing vibration excited in various kinds of vibrative members, there are known (a) a mass damper in which a mass member is fixed to a vibrative member, (b) a dynamic damper in which a mass member is supported by and connected to the vibrative member via a spring member and (c) a damping material that is a sheet-shaped elastic member and secured to the vibrative member. However, these conventional devices suffer from various potential problems. For example, (a) the mass damper and (b) the dynamic damper both require a relatively large mass of the mass member, and exhibit a vibration damping effect only to a limited frequency range. (c) The damping material suffers from difficulty in stably exhibiting a desired damping effect, since the damping effect of the damping material is prone to vary depending upon the ambient temperature.
The present assignee has been disclosed in International Publication WO 00/14429 a novel vibration damper for use on an automotive vehicle, which includes a housing member fixed to the vibrative member, and an independent mass member that is housed in the housing member with a spacing therebetween, without being bonded to the housing member, so that the independent mass member is displaceable or movable relative to the housing member, while being independent of the housing member. In the disclosed vibration damper, the independent mass member comes into impact on or abutting contact with the housing member with elastic abutting surfaces, upon application of a vibrational load to the damper, whereby the vibration excited in the vibrative member is effectively reduced or absorbed. The proposed vibration damper is capable of exhibiting a high damping effect over a sufficiently wide frequency range of frequency of input vibrations, while having a relatively small weight in comparison with the conventional mass damper and dynamic damper.
SUMMARY OF THE INVENTION
The present invention has been developed by an extensive study of a vibration damper for use on an automotive vehicle disclosed in the above-indicated International Publication WO 00/14429. It is therefore an object of this invention to provide an improved vibration damping device capable of exhibiting a further improved vibration damping effect, in comparison with the vibration damper disclosed in the International Publication WO 00/14429.
The above and/or optional objects of this invention may be attained according to at least one of the following modes of the invention. Each of these modes of the invention is numbered like the appended claims and depending from the other mode or modes, where appropriate, to indicate possible combinations of elements or technical features of the invention. It is to be understood that the principle of the invention is not limited to these modes of the invention and combinations of the technical features, but may otherwise be recognized based on the teachings of the present invention disclosed in the entire specification and drawings or that may be recognized by those skilled in the art in the light of the present disclosure in its entirety.
(1) A vibration-damping device for damping vibrations of a vibrative member, comprising: (a) an abutting member adapted to be fixedly disposed in the vibrative member and having an abutting surface; and (b) an independent mass member disposed in relation to the abutting member such that the independent mass member is independently displaceable relative to the abutting member without being adhesive to the abutting member, the independent mass member having an abutting surface that comes into abutting contact directly and elastically with the abutting surface of the abutting member, wherein at least one of the abutting surfaces of the abutting member and the independent mass member is provided with a flock coating.
In the vibration damping device constructed according to this mode of the present invention, a vibrational load applied from the vibrative member to the vibration damping device causes a displacement of the independent mass member relative to the vibrative member. As a result, the independent mass member comes into impact on (abutting contact with) the abutting member, whereby the vibration-damping device can exhibit an excellent vibration damping effect as a result of the impact of the independent mass member on the abutting member.
Further, the independent mass member is displaced relative to the abutting member due to the vibrational load applied to the vibration damping device, and comes into abutting contact with the abutting member at their abutting surfaces at least one of which is provided with the flock coating. This enables the vibration-damping device to exhibit a higher damping characteristic in comparison with the case where the abutting surface is composed of a rubber elastic body or elastomer.
This abutting contact of the independent mass member with the abutting member via the flocked abutting surface or surfaces allows the vibration damping device to exhibit an excellent damping effect on the basis of the impact (abutting contact) of the independent mass member on the abutting member, without needing a significant increase of the mass of the independent mass member, with respect to low frequency vibrations. For this reason, the vibration damping device of this mode of the invention can exhibit a high damping effect with respect to vibrations excited in the vehicle whose frequencies ranging from about 10 Hz to about 100 Hz, for example.
The technical reasons for the above-described significant improve in the damping characteristics of the present vibration damping device owing to the use of the flocked abutting surface has not yet been revealed sufficiently. Although it is not an object of the invention to clarify this technical reason, it might be assumed that the flock coating provided on at least one of the abutting surfaces of the abutting member and the independent mass member allows the abutting and independent mass members to come into abutting contact with each other, while remarkably exhibiting a non-linear raise or increase of the spring constant generated between the abutting surfaces of the abutting member and the independent mass member.
A further extensive study of the present vibration damping device conducted by the present inventors reveals that the vibration damping device constructed according to this mode (1) of the invention permits that when the vibration damping device subjected to the vibration excited in the vibrative member, the independent mass member comes into impact on or abutting contact with the abutting member, while permitting the independent mass member to exhibit an amplitude magnification of not smaller than one with respect to the abutting member. This arrangement allows the independent mass member to impact on and rebound from the abutting member repeatedly in an easier manner, resulting in a bouncing displacement of the independent mass member relative to the abutting member with high efficiency. Therefore, the present vibration-damping device is able to provide the bouncing displacement of the independent mass member relative to the abutting member, if an acceleration of the vibration e
Kato Rentaro
Maeda Koichi
Beyer Weaver & Thomas LLP
Graham Matthew C.
Tokai Rubber Industries Ltd.
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