Spring devices – Resilient shock or vibration absorber – Including energy absorbing means or feature
Reexamination Certificate
2002-09-10
2003-12-09
Schwartz, Christopher P. (Department: 3683)
Spring devices
Resilient shock or vibration absorber
Including energy absorbing means or feature
Reexamination Certificate
active
06659436
ABSTRACT:
INCORPORATED BY REFERENCE
The disclosure of Japanese Patent Application No. 2001-278761 filed on Sep. 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 a fluid-filled active vibration-damping device, which has a primary fluid chamber filled with a non-compressible fluid, and which is capable of actively offsetting or reducing vibrations applied to the primary fluid chamber by controlling a fluid pressure in the primary fluid chamber. More particularly, the present invention is concerned with a pneumatically operated fluid-filled active vibration-damping device wherein the fluid pressure in the primary fluid chamber is controlled by means of an air pressure applied thereto from the external area, and an active vibration-damping apparatus equipped with the same, which is suitably applicable to an active elastic mount and an active dynamic damper or oscillator for use in automotive vehicles, for example.
2. Description of the Related Art
Vibration-damping devices have been used for damping or isolating vibrations (including noises induced by the vibrations) of a subject member such as a body of an automotive vehicle or other members suffering from these vibrations or noises. Known examples of such vibration-damping devices include: a vibration-damping coupling or mount, e.g., an engine mount, which is interposed between the subject member and a vibration source, e.g., a power unit, so as to connect these two members in a vibration-damping fashion for eliminating or reducing a vibration transmitted from the vibration source to the subject member; and a vibration damper that is fixed to the subject member for absorbing or reducing the vibration of the subject member.
A fluid-filled active vibration-damping device has been proposed as one type of such vibration-damping devices, as disclosed in JP-A-10-184769. The known fluid-filled active vibration-damping device includes: an elastic body elastically deformed due to vibrational loads applied thereto; a primary fluid chamber partially defined by the elastic body and an elastically displaceably movable member, while being filled with a non-compressible fluid; and a working air chamber formed on one side of the movable member that is remote from the other side on which the primary fluid chamber is formed. The pressure of the fluid in the primary fluid chamber varies due to the elastic deformation of the elastic body upon application of the vibrational loads to the elastic body, and is also actively controllable by applying a suitable air pressure variation to the working air chamber from the external area, which is transmitted to the primary fluid chamber via the movable member. Such a known fluid-filled active vibration-damping device is capable of actively controlling a fluid pressure variation induced in the primary fluid chamber by applying an air pressure variation corresponding to a vibration to be damped, thereby exhibiting an active vibration-damping effect or an offsetting effect with respect to vibrations excited in the subject member to which the fluid-filled active vibration-damping device is installed.
In order to induce a suitable air pressure variation in the working air chamber, the known fluid-filled active vibration-damping device generally employs a vacuum source such as a negative pressure available from an air intake part of an internal combustion engine and an atmosphere as pressure sources, and a solenoid-operated switch valve operable for alternately connecting and disconnecting the working air chamber to and from the vacuum source and the atmosphere at a frequency corresponding to that of vibrations to be damped. However, the known fluid-filled active vibration-damping device is incapable of confirming a waveform of the air pressure variation induced in the working air chamber to a waveform of amplitude of vibrations to be damped, causing undesirable generation of higher harmonic components of a primary frequency of the air pressure variation generated in the working air chamber. The higher harmonic components are undesirably transmitted to the primary fluid chamber, causing deterioration of a vibration-damping capability of the fluid-filled active vibration-damping device.
To cope with the above-mentioned conventional problem, the present assignee has disclosed in JP-A-11-82611 an improved fluid-filled active vibration-damping device in which a resonance pipe or the like is connected to a portion of an air piping system provided for applying the air pressure variation to the working air chamber, for the purpose of reducing or attenuating the higher harmonic components included in the air pressure variation.
However, extensive studies conducted by the present inventors has revealed that the improved fluid-filled active vibration-damping device needs to branch a pipe in the air piping system with a branch pipe or the like for disposing the resonance pipe on the portion of the air piping system, or to form a special port in the solenoid-operated switch valve in order to connect the resonance pipe to the solenoid-operated switch valve, thus deteriorating efficiency in manufacturing the air piping system. Also, additional spaces are required on the air piping system for an installation such a branch pipe, a special port and the like, making it difficult to install the improved fluid-filled active vibration-damping device on any automotive vehicle by simply changing the design of the vibration-damping device.
In addition, even if the resonance pipe is disposed on the portion of the air piping system, the fluid-filled active vibration-damping device may still possibly suffer from generation of the higher harmonic components in the air pressure variation transmitted through the air piping system, due to the presence of bending or narrowed portions in an air passage of the air piping system located between the portion at which the resonance pipe is connected to the pipe in the air piping system and the working air chamber. That is, the improved fluid-filled active vibration-damping device is not able to cope with the problem of such higher harmonic components in the air pressure variation, leaving some room for improvement.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide an improved pneumatically operated fluid-filled active vibration-damping device, which is capable of eliminating or minimizing generation of higher harmonic components of a primary frequency of an air pressure variation in the working air chamber while simplifying the structure of the damping device and eliminating a need for a special modification to an air piping system, and accordingly which is capable of exhibiting a desired active vibration-damping effect with high stability.
The above and/or other 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 pneumatically operated fluid-filled active vibration-damping device comprising: (a) an elastic body elastically deformed due to vibrational loads applied thereto; (b) a primary fluid chamber partially defined by the elastic body and filled with a non-compressible fluid; (c) a movable member being elastically displaceable and partially defining the primary fluid chamber on one of opposite sides thereof; (d) a working air chamber disposed an ot
Akasa Syouji
Ichikawa Hiroyuki
Muramatsu Atsushi
Beyer Weaver & Thomas LLP
Schwartz Christopher P.
Tokai Rubber Industries Ltd.
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