Spring devices – Resilient shock or vibration absorber – Including energy absorbing means or feature
Reexamination Certificate
2002-07-15
2004-06-29
Siconolfi, Robert A. (Department: 3683)
Spring devices
Resilient shock or vibration absorber
Including energy absorbing means or feature
C267S140130
Reexamination Certificate
active
06755401
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a fluid-filled vibration damping device that exhibit vibration damping effect on the basis of flows of a non-compressible fluid filled therein. More particularly, the present invention is concerned with a pneumatically controlled fluid-filled vibration damping device that is capable of controlling its vibration damping characteristics by suitably changing an air pressure applied from an external air source to an air chamber formed in the vibration damping device, and that is suitably adoptable as an engine mount for use in an automotive vehicle.
2. Description of the Related Art
JP-A-10-339350 discloses a known example of a fluid-filled vibration damping device in which a first mounting member and a second mounting member are disposed in a mutually spaced apart relationship with each other, and are elastically connected with each other by an elastic body interposed therebetween, while a partition member is supported by the second mounting member so that a primary fluid chamber and an equilibrium chamber, which are both filled with a non-compressible fluid such as water, are formed on both sides of the partition member and held in fluid communication with each other via an orifice passage. The disclosed fluid-filled vibration-damping device is able to exhibit vibration damping effect on the basis of flows of the fluid through the orifice passage, upon application of a vibrational load between the first and second mounting members.
For assuring further improved damping effect, it has been proposed to modify the fluid-filled vibration damping device such that the pressure-receiving chamber is partially defined by a movable member disposed in a displaceable or deformable manner, and a working air chamber is formed by and between the movable member and the partition member. This proposed modification makes it possible to control vibration-damping characteristics of the fluid-filled vibration-damping device according to input vibrations. Namely, a suitable air pressure variation whose frequency corresponding to that of the input vibrations is applied to the working air chamber, so that the modified fluid-filled vibration-damping device can actively offset or absorb input vibrations with the help of the air pressure variation applied to the working air chamber, for example, thereby actively controlling fluid pressure variation in the pressure-receiving chamber. Alternatively, the modified fluid-filled vibration-damping device is capable of controlling its passive vibration damping effect. Namely, the tuning frequency of the orifice passage may be desirably changed by suitably changing the air pressure level in the working air chamber so as to adjust wall spring characteristics of the movable member, i.e., the pressure-receiving chamber.
As disclosed in the aforementioned JP-A-10-339350, the conventional fluid-filled vibration damping device has a structure in which the second mounting member is formed of a generally cylindrical metallic member. One of axially opposite open-end of the second mounting member is fluid-tightly closed by a flexible rubber layer, and a artition member is press-fitted and fixedly disposed in a bore of the second mounting member. The other open-end of the second mounting member is fluid-tightly closed by the elastic body with the other open-end of the second mounting member being press-fitted onto a metallic sleeve that is bonded to an outer circumferential surface of the elastic body upon vulcanization of a rubber material to form the elastic body. Thus, a fluid-tightly closed interior space of the second mounting member is divided into two chambers, i.e., a pressure-receiving chamber partially defined by the elastic body and an equilibrium chamber partially defined by the flexible rubber layer, which are both filled with a non-compressible fluid.
However, the conventional fluid-filled vibration damping device constructed as described above inevitably requires a relatively large axial length of the second mounting member in order to receive the partition member in its bore. This makes it cumbersome to manufacture the second mounting member, pushing up a manufacturing cost. Also, the relatively long cylindrical second mounting member makes it difficult not only to assemble the partition member into the bore of the second mounting member, but also to bond the flexible rubber layer to the one open-end of the second mounting member in a process of vulcanization of a rubber material to form the flexible rubber layer, resulting in low manufacturing efficiency. In addition, since the other open-end of the second mounting member is press-fitted onto the metallic sleeve bonded to the outer circumferential surface of the elastic body, the conventional fluid-filled vibration damping device does not assure a sufficient bonding strength in its axial direction.
Moreover, the conventional fluid-filled vibration damping device generally has a specific structure for permitting a connection of a port of an air passage formed through the partition member with an external air conduit, as disclosed in the aforementioned document No. JP-A-10-339350. Namely, the second mounting member is formed with a window formed through its cylindrical wall portion so that the port of the air passage is open to the external area through the window of the second mounting member. In general, the second mounting member is subjected to a drawing operation, e.g., all directional drawing, after being mounted onto the partition member so that the second mounting member is radially inwardly drawn onto and fixedly mounted onto the partition member. In the drawing operation, the presence of the window formed through the cylindrical wall portion of the second mounting member may cause a local decrease in strength of the second mounting member. This is prone to cause irregular deformation of the second mounting member, leading to an undesirable leakage of the non-compressible fluid through the interface between the partition member and the second mounting member. Thus, the conventional fluid-filled vibration-damping device suffers from difficulty in assuring a sufficient fluid-tight sealing with high stability.
Further, in the aforementioned drawing operation, it is required to precisely position the air port of the air passage formed in the partition member and the window of the second mounting member relative to each other, making it cumbersome to assemble the second mounting member and the partition member, resulting in a low manufacturing efficiency.
SUMMARY OF THE INVENTION
It is therefore one object of this invention to provide a pneumatically controlled fluid-filled vibration damping device, which is novel and simple in structure, which is easy to manufacture, and which assures high fluid-tight sealing in a pressure-receiving chamber and an equilibrium chamber.
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 fluid-filled vibration-damping device for connecting two members in a vibration damping fashion, which includes (a) a first mounting member adapted to be fixed to one of the two members; (b) a second mounting member adapted to be fixed to an other one of the two members and having a cylindrical portion, while being disposed relative to the first mounting member such that one of axially opposite open-end port
Akasa Shouji
Katagiri Katsuhiko
Maehashi Hideki
Ogawa Yuichi
Saiki Akio
Beyer Weaver & Thomas LLP
Siconolfi Robert A.
Tokai Rubber Industries Ltd.
Torres Melanie
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