Spring devices – Resilient shock or vibration absorber – Including energy absorbing means or feature
Reexamination Certificate
2002-01-30
2004-01-20
Lavinder, Jack (Department: 3683)
Spring devices
Resilient shock or vibration absorber
Including energy absorbing means or feature
C267S140140
Reexamination Certificate
active
06679486
ABSTRACT:
INCORPORATED BY REFERENCE
The disclosure of Japanese Patent Application No. 2001-036021 filed on Feb. 13, 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 vibration dampers to be attached to a subject member to damp vibration of the subject member, and more particularly to a pneumatically controlled vibration damper that is novel in construction and capable of regulating vibration damping characteristics thereof by utilizing pneumatic pressure, so that the vibration damper exhibits vibration damping effect corresponding to vibration to be damped.
2. Description of the Related Art
A dynamic damper of passive type is known as means for damping vibration excited in a subject member that is likely to be vibrated, such as a body of an automotive vehicle. The passive-type dynamic damper generally includes a mounting member to be attached to the subject member and a mass member elastically connected via an elastic support member so that the mass member is elastically supported by the mounting member. Recently, there have been proposed pneumatically operated active vibration dampers in an attempt to obtain an enhanced damping effect. A known example of such a pneumatically operated active vibration damper is disclosed in JP-A-10-169705, wherein a working air chamber is formed to apply oscillating force to the mass member on the basis of a change of an air pressure within the working air chamber, so that the mass member is positively oscillated to generate an oscillating force that acts on the subject member to offset or actively damp vibration excited in the subject member.
As well known in the art, the mass member and the elastic support member constitute a single vibration system that serves as a secondary vibration system with respect to the subject member served as a primary vibration system. In order to obtain an excellent vibration damping effect, these conventional passive-type and active-type vibration dampers may advantageously utilize resonance of their vibration systems constituted by the mass member and the elastic support member. For this reason, it is desirable to tune a natural frequency of the vibration system to a frequency band of vibration to be damped.
However, such conventional vibration dampers of passive type and active type may suffer from an inherent problem. Namely, since the natural frequency of the vibration system constituted by the mass member and the elastic support member is fixedly determined by a mass of the mass member and a spring constant of the elastic support member, the natural frequency of the vibration system is likely to deviate from the frequency band of the vibration to be damped, when the vibration to be damped varies. Thus, the conventional vibration dampers do not necessarily exhibit an excellent vibration damping effect with respect to vibrations having a plurality of frequency bands or over a wide frequency range.
SUMMARY OF THE INVENTION
It is therefore one object of the invention to provide a vibration damper that is novel in construction, and that is capable of controlling vibration damping characteristics thereof and exhibiting an excellent vibration damping effect with respect to vibrations having a plurality of frequency bands or over a wide frequency range.
It is another object of the present invention to provide a vibration damper that is simple in construction and compact in size, and that eliminates a need for assembling a specific actuator therein.
The above objects 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 a principle of the present invention that described in the whole specification and drawings, or may be recognized by those skilled in the art in the light of the disclosure in the whole specification and drawings.
(1) A pneumatically controlled vibration damper for damping vibration of a subject member as a primary vibration system, the vibration damper including: (a) a mounting member adapted to be fixed to the subject member; (b) a mass member disposed spaced apart from the mounting member and displaceable relative to the mounting member; (c) an elastic connector secured to the mounting member and the mass member for elastically connecting the mass member to the mounting member so that the elastic connector and the mass member cooperate to form a secondary vibration system; (d) a working air chamber partially defined by the elastic connector and closed from an external area; (e) an air passage connected to said working air chamber for regulating an air pressure in the working air chamber from said external area; and (f) a static pressure-regulating system operable for substantially statically regulating the air pressure in the working air chamber via the air passage, so as to induce a substantially static elastic deformation of the elastic connector for changing a spring characteristic of the elastic connector.
In the pneumatically controlled vibration damper constructed according to this mode of the invention, the air pressure in the working air chamber is statically changed so as to change the spring characteristic of the elastic connector. This makes it possible to change a natural frequency of a vibration system of the vibration damper that is constituted by the mass member as a mass component and the elastic connector as a spring component, and that serves as the secondary vibration system. Described in detail, the vibration damper may be arranged by way of example such that an amount of statically elastic deformation of the elastic connector is made smaller, as the pressure of the air in the working air chamber is made closer to the atmospheric pressure, resulting in a soft spring characteristic of the elastic connector. Thus, the natural frequency of the vibration system of the vibration damper is tuned to a low frequency band, for example. Namely, the vibration damper of this mode of the invention is capable of controlling a static air pressure in the working air chamber, making it possible to tune or change the natural frequency of the vibration system constituted by the mass member and the elastic connector so as to correspond to a frequency of the vibration to be damped, even in the case where the frequency of the vibration to be damped varies. Thus, the vibration damper of this mode of the invention is capable of exhibiting an excellent passive or active vibration damping effect with the help of a resonance of the vibration system of the vibration damper (i.e., the secondary vibration system).
Further, the spring characteristic of the elastic connector can be suitably changed or determined according to a substantially static pressure value applied to the working air chamber. This arrangement makes it possible to suitably adjust the spring characteristic of the elastic connector so as to correspond to the change of the frequency of the vibration to be damped. Therefore, the vibration damper of the present mode of the invention is capable of efficiently exhibiting an excellent vibration damping effect with respect to input vibration in a plurality of frequency bands or over a wide frequency range, because of the resonance effect of the vibration system constituted by the mass member and the elastic connector.
It should be appreciated that the phrase “substantially static elastic deformation” of the elastic connector is interpreted to mean a state of the elastic deformation of the elastic connector in which the elastic connector is able to be held in a substantially constant attitude, provided no dynamic or periodic change of the air pressure in the working air chamber is
Hatano Motohiro
Kato Kazuhiko
Muramatsu Atsushi
Beyer Weaver & Thomas LLP
Lavinder Jack
Sy Mariano
Tokai Rubber Industries Ltd.
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