Brakes – Inertia of damping mass dissipates motion – Resiliently supported damping mass
Reexamination Certificate
2001-08-08
2003-04-29
Graham, Matthew C. (Department: 3683)
Brakes
Inertia of damping mass dissipates motion
Resiliently supported damping mass
C188S378000, C267S136000, C267S292000
Reexamination Certificate
active
06554112
ABSTRACT:
This application is based on Japanese Patent Application Nos. 2000-273135 filed Sep. 8, 2000 and 2001-064043 filed Mar. 7, 2001, the contents of which are incorporated hereinto by reference in their entireties.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally relates to a vibration-damping device installed in a vibrative member of a vehicle, for reducing or attenuating vibration of the vibrative member. More particularly, the present invention is concerned with such a vibration-damping device which is novel in construction and which is suitably applicable to vibrative members of an automotive vehicle, such as a suspension member, a sub frame, a body panel, a mounting bracket, and a vibrative member or members used in an engine unit or an exhaustion system, so that the vibration-damping device exhibits an excellent damping effect with respect to vibrations excited in these vibrative members.
2. Description of the Related Art
As vibration-damping devices 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-shaped elastic member and secured to the vibrative member. However, these conventional devices suffer from various potential problems. For instance, the mass damper and the dynamic damper both require a relatively large mass of the mass member, and exhibit desired vibration damping effect with respect only to a considerably narrow frequency range. The damping material requires a relatively large space for its installation, and tends to be large in its weight. In addition, the dynamic damper and the damping material both suffer from difficulty in stably exhibiting desired damping effects thereof, since the damping effects of the dynamic damper and the damping material are prone to vary depending upon the ambient temperature.
The present applicant has been disclosed in International Publication No. 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 disposed within in the inner space of 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. When vibrations excited in the vibrative member is applied to the vibration damper, the independent mass member and the housing member are brought into impact against each other at their elastic abutting surfaces, thereby exhibiting an vibration damping effect on the basis of loss or dissipation of vibration energy caused by sliding friction generated between the elastic abutting surfaces of the independent 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 relatively wide frequency range of input vibrations, while assuring a relatively small mass of the independent mass member.
Extensive studies of the vibration damper disclosed in the International Publication No. WO 00/14429 by the inventors of the present invention, have revealed that the vibration damping effects of the vibration damper can be remarkably improved with respect to a specific frequency vibration by adjusting a mass of the independent mass member or a spring stiffness of the elastic abutting surface of the independent mass member and/or the housing member, for example. This might be considered as follows, according to an examination into frequency characteristics of the damping effect of the vibration damper conducted by the inventors. Namely, the impact of the independent mass member on the housing member in a vibration input direction causes a reciprocating displacement of the independent mass member relative to the housing member within the housing member. The reciprocating displacement of the independent mass member relative to the housing member due to the impact of the mass member on the housing member might exhibit an effect like resonance.
However, it is difficult to tune the vibration damper to exhibit an excellent damping effect with respect to a desired frequency vibration, owing to the resonance-like effect of the reciprocating displacement of the independent mass member. That is, tuning of the vibration damper is limited by several conditions. For instance, a size of the independent mass member is limited by a given space for installation of the vibration damper in the vehicle, while a lower limit of the spring stiffness of the elastic abutting surface of the independent mass member and/or the housing member is predetermined to ensure a desired durability of the elastic abutting surface. In particular, when a vibration to be damped has a low frequency, there are needed a relatively large mass of the mass member and a relatively small spring stiffness of the elastic abutting surface, for example. In this case, a desired tuning of the vibration damper is significantly difficult, whereby the conventional vibration damper is insufficient in its vibration damping effect with respect to vibrations within a low frequency band.
SUMMARY OF THE INVENTION
It is therefore an object of this invention to provide a vibration-damping device for a vehicle which is novel in construction and which permits sufficient durability of abutting portions of a mass member and a vibrative member, while ensuring sufficiently small spring stiffness generated in abutting portions upon impact of the mass member on the vibrative member. The vibration-damping device is easily tunable to exhibit an excellent damping effect owing to impact of the mass member on the vibrative member, with respect to input vibrations especially within a lower frequency band.
The above object may be attained according to the following modes of the invention, each of which 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 the following modes or combinations of technical features, but may otherwise be recognized based on the thought of the present invention that described 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 mass member disposed in the vibrative member such that the mass member is non-adhesive to and is displaceable independent of and relative to the vibrative member, the mass member and the vibrative member being brought into impact against each other at respective abutting portions thereof, at least one of the abutting portions of the mass member and the vibrative member being formed of an elastic member adapted to undergo shear deformation due to a load applied thereto in a direction in which the mass member and the vibrative member are brought into impact against each other.
In the vibration-damping device constructed according to this mode (1) of the invention, when the mass member is forced to move into and impact on the vibrative member due to vibrations excited in the vibrative member, the elastic member defining at least one of the abutting portions of the mass member and the vibrative member undergoes shear deformation. Thus, upon impact of the mass member on the vibrative member, the spring constant generated in the abutting portions of the mass member and the vibrative member can be made smaller, in comparison with the case where the elastic member is formed to undergo compression deformation upon impact of the mass member and the vibra
Hamada Masaaki
Hasegawa Koichi
Hashimoto Yuushi
Kato Rentaro
Maeno Hajime
Beyer Weaver & Thomas LLP
Graham Matthew C.
Sy Mariano
Tokai Rubber Industries Ltd.
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