Brakes – Inertia of damping mass dissipates motion
Reexamination Certificate
2001-02-27
2003-03-25
Schwartz, Christopher P. (Department: 3683)
Brakes
Inertia of damping mass dissipates motion
Reexamination Certificate
active
06536566
ABSTRACT:
This application is based on Japanese Patent Applications No. 2000-52621 filed Feb. 28, 2000 and Nos. 2000-55464, 2000-55470, 2000-55478, 2000-55481 and 2000-56555 filed Mar. 1, 2000, the contents of which are incorporated hereinto by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a vibration damper installed in a vibrative member of a vehicle, for reducing vibration of the vibrative member. More particularly, the present invention is concerned with such a vibration damper which is novel in construction and which is suitably applicable to the vibrative members such as suspension arms, sub flames, body panels, mounting brackets, and vibrative members used in an engine unit and an exhaustion system, for exhibiting an excellent vibration-damping effect with respect to vibrations of these vibrative members.
2. Description of the Related Art
As vibration-damping means for damping or reducing vibration excited in vehicles such as an automotive vehicle, there are known (a) a mass damper wherein a mass member is fixed to a vibrative member, (b) a dynamic damper wherein a mass member is supported by and connected to the vibrative member via a spring member and (c) a damping material which is a sheet-like 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 desired vibration-damping effect only to significantly narrow frequency ranges. (c) The damping material suffers from difficulty in stably exhibiting a desired damping effect, since the damping effect of the damping material is likely to vary depending upon the ambient temperature.
The present assignee has been disclosed in International Publication WO 00/14429 a novel vibration damper used for an automotive vehicle, which includes a housing member having an inner space and fixed to the vibrative member, and an independent mass member which is accommodated in an inner space of the housing member 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 is moved into and impact the housing member, upon application of a vibrational load to the damper, whereby the vibration of the vibrative body is effectively reduced or absorbed based on loss or dissipation of energy caused by sliding friction generated between the abutting surfaces of the mass member and the housing member and caused by collision or impact of the independent mass member against the housing member. This 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 mass of the mass member.
In order to stably establish a desired damping effect of the vibration damper disclosed in the above-indicated document, it is required to precisely control parameters including a distance of spacing or gap between the abutting surface of the independent mass member and the abutting surface of the housing member, and coefficient of restitution of these abutting surfaces, since the damping effects of the disclosed vibration damper depend upon these parameters. The independent mass member is further required to make a bouncing, sliding or rolling motions. Namely, the independent mass member is required to repeatedly impact and bounce off the housing member so as to repeatedly apply impact energy to the housing member, upon application of the vibrational load to the independent mass member.
As a result of intensive studies in an attempted to further developing the vibration damper as described above, the inventors of the present invention have found that a vibration damper having a housing member and a plurality of independent mass members accommodated in the housing member and comprehensively tuned, exhibits a damping effect which is different from that exhibited by the vibration damper wherein the suitably tuned single mass member is accommodated in the housing member. In particular, a difference in the vibration-damping effects have still found between the vibration damper having the plurality of independent mass member and the vibration damper having a single mass member, even if the total mass of the plurality of mass members is made equal to the mass of the single mass member. This difference may stem from that bouncing or restituting characteristics of each of the plurality of mass members are different from those of the single mass member.
SUMMARY OF THE INVENTION
It is therefore a first object of this invention to provide an improved vibration-damping device for vehicles, which is capable of exhibiting a desired damping effect with high efficiency.
It is a second object of this invention to provide a method of producing the vibration-damping device of this invention.
The above first object may be attained according to the following modes (
1
)-(
34
) and (
37
)-(
44
) of the invention, and the second object may be attained according to the following modes (
35
) and (
36
) of the invention. Each of these modes of the invention is numbered like the appended claims and depends 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 present invention is not limited to those modes of the invention and combinations of the technical features, but may otherwise be recognized based on the thought of the present invention that disclosed in the whole specification and drawings or that may be recognized by those skilled in the art in the light of the disclosure in the whole specification and drawings.
(1) A vibration-damping device for damping vibrations of a vibrative member of a vehicle, comprising: (a) at least one rigid housing member fixedly disposed in the vibrative member; and (b) a plurality of independent mass members disposed non-adhesively and independently in the at least one housing member such that each of the plurality of independent mass members is opposed to the housing member with a given spacing therebetween in a vibration input direction, and is displaceable relative to the housing member, the each of said plurality of independent mass members being independently displaced relative to said housing member so that the independent mass member and the housing member are brought into elastic impact against each other at respective abutting surfaces thereof which are opposed to each other in the vibration input direction.
In the vibration-damping device constructed according to the above mode (
1
) of the present invention, the plurality of independent mass members are comprehensively tuned. Namely, a ground total of the masses of the plurality of independent mass member is suitably tuned or determined for assuring desired damping characteristics of the present vibration-damping device. Consequently, the required mass of each of the plurality of independent mass members is made relatively smaller, facilitating the relative movement between the each independent mass member and the housing member, upon application of a vibrational load to the damping device. Namely, bouncing movement of the each independent mass member is effectively induced. In this condition, the independent mass members are effectively forced to move into and impact the housing member, whereby the vibration-damping device can exhibit a desired vibration-damping effect with high efficiency. It should be noted that the housing member may be provided as a box-like member or the like, which is made of a rigid material such as metal and which is formed independently of and fixedly attached to a vibrative member as a subject member whose vibrations to be damped. It may be possible to provide the housing member by utilizing an interior space
Hamada Masaaki
Hasegawa Koichi
Kato Rentaro
Tazuke Yutaka
Yasumoto Yoshinori
Beyer Weaver & Thomas LLP
Schwartz Christopher P.
Tokai Rubber Industries Ltd.
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