Brakes – Inertia of damping mass dissipates motion – Resiliently supported damping mass
Reexamination Certificate
2002-09-24
2004-04-20
Butler, Douglas C. (Department: 3683)
Brakes
Inertia of damping mass dissipates motion
Resiliently supported damping mass
C267S141000, C267S292000, C267S136000, C188S378000
Reexamination Certificate
active
06722481
ABSTRACT:
INCORPORATED BY REFERENCE
The disclosure of Japanese Patent Application No. 2001-290574 filed on Sep. 25, 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 generally relates to vibration-damping devices for use in various kinds of vibrative members, for reducing or attenuating vibrations excited in these vibrative members. More particularly, the present invention is concerned with such a vibration-damping device, which is novel in construction and which is suitably used in an automotive vehicle for damping or attenuating vibrations excited in a suspension member, a sub frame, a body, a mounting bracket, a vibrative member or members used in an engine unit or an exhaustion system, and other vibrative members.
2. Description of the Related Art
Vibration-damping devices have been used in various kinds of vibrative members for damping vibrations excited therein. Known examples of these vibration-damping devices include (a) a mass damper in which a pillar-shaped mass member is fixed to a vibrative member; (b) a dynamic damper in which a pillar-shaped 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 require a relatively large weight of the pillar-shaped mass member, and exhibit damping effects limited 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 assignee has been disclosed in International Publication No. WO 00/14429 a novel vibration damper for use in 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 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 elastic impact against each other at their abutting surfaces, thereby exhibiting a 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 on 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 weight or mass of the independent mass member.
Extensive studies of the vibration damper disclosed in the International Publication No. WO 00/14429, conducted by the inventors of the present invention, have revealed that the disclosed vibration damper can exhibit such a high damping effect based on a bouncing or jumpily displacement of the mass member relative to the housing member in which the mass member comes into impact on and rebounds from the housing member repeatedly. In order to upgrade the damping effect of the disclosed vibration damper with respect to vibrations excited in the automotive vehicle, namely, vibrations having a relatively low frequency, a relatively small amplitude and a relatively small energy, it is therefore effective to sufficiently decrease a spring stiffness of an elastic body at least partially defining the abutting portion of the mass member, which is adapted to be brought into abutting contact with the housing member, thereby facilitating the jumpily displacement of the mass member relative to the housing member.
To obtain a sufficiently small spring stiffness of the elastic body at least partially defining the abutting portion of the mass member, it may be proposed to arrange the elastic body of the mass member to have a relatively large wall thickness enough to establish a sufficiently small dynamic spring constant of the abutting surface of the mass member, or alternatively, to form the elastic body of the mass member of a soft rubber material. However, in the former case, the wall thickness of the elastic body is likely to be limited by a size of a space for housing the mass member, and in the latter case, the elastic body is likely to be deteriorated in terms of its durability. Therefore, the disclosed vibration damper is less likely to excite the jumpily displacement of the mass member relative to the housing member upon application of such vibrations having the small energy, low frequency and small amplitude, thereby suffering from difficulty in exhibiting a desired vibration damping effect with respect to such vibrations. Thus, the disclosed vibration damper leaves some room for improvement.
SUMMARY OF THE INVENTION
It is therefore one object of this invention to provide an improved vibration-damping device, which makes it possible to reduce a dynamic spring constant at an abutting portion of a mass member with respect to a housing member, without needing an increase of a wall thickness of an elastic body at least partially defining the abutting portion of the mass member and/or the housing member, and without causing deterioration of durability of the elastic body due to a change of a rubber material for forming the elastic body. Therefore, the vibration-damping device is capable of efficiently exciting jumpily displacement of the mass member relative to the housing member, even upon application of vibrations having a small energy, a low frequency and a small amplitude to the vibration-damping device, and accordingly exhibiting an excellent vibration damping effect based on impact of the mass member on the housing member, for these vibrations having the small energy, low frequency and small amplitude.
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 excited in a vibrative member, comprising: (a) a housing member adapted to be fixed to the vibrative member and defining a accommodation space therein; (b) a pillar-shaped mass member housed within the accommodation space of the housing member with a slight spacing therebetween so that the pillar-shaped mass member is independent of the housing member and is freely displaceable within the accommodation space of the housing member to come into impact on the housing member, the pillar-shaped mass member extending in a primary vibration input direction; and (c) a rubber buffer and an abutting rubber member, which are integrally formed with each other and fixed to at least one of axially opposite end portions of the pillar-shaped mass member such that the rubber buffer covers an outer circumferential surface of the at least one of axially opposite end portions of the pill
Maeda Koichi
Maeno Hajime
Beyer Weaver & Thomas LLP
Butler Douglas C.
Tokai Rubber Industries Ltd.
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