Spring devices – Resilient shock or vibration absorber – Nonmetallic – resilient element
Reexamination Certificate
2001-01-31
2003-04-22
Lavinder, Jack (Department: 3683)
Spring devices
Resilient shock or vibration absorber
Nonmetallic, resilient element
C267S141300, C267S141700
Reexamination Certificate
active
06550754
ABSTRACT:
This application is based on Japanese Patent Application No. 2000-290149 filed Sep. 25, 2000, the contents of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a dynamic damper having a generally cylindrical shape, which is installed on a hollow or a solid rod member used as a vibration-transmitting member such as shafts, arms and conduits in various devices and being subject to oscillation or vibration, so that vibration of the rod member is reduced or absorbed.
2. Discussion of the Related Art
There are known various kinds of rod members such as shafts or arms functioning as a power-transmitting member and such as conduits or pipes serving as a fluid passage. Such a rod member generally tends to oscillate or vibrate and consequently suffers from problems of resonance thereof and undesirable transmission of the excited vibration therein to the other components of a device in which the rod member is used. As a method to cope with these problems, a dynamic damper is attached to the rod member. Examples of such a dynamic damper are disclosed in JP-A-2-190641, JP-B-6-37915 and JP-A-8-28627, wherein the dynamic damper has a metallic mass member having a generally cylindrical configuration and a pair of elastic support members formed on axially opposite sides of the mass member so as to extend axially outward directions, respectively. The disclosed dynamic damper is inserted onto the rod member and secured thereto at the elastic support members so that the mass member is elastically supported on the oscillating rod member via the elastic support members. Such a generally cylindrical dynamic damper is properly tuned so that the dynamic damper is capable of exhibiting effective damping characteristics with respect to a torsional or a circumferential vibration as well as a radial vibration of the rod member. Further, the mass member of the dynamic damper is less likely to drop off or released from the rod member, owing to its cylindrical shape, even if the elastic support member is undesirably broken. For these advantages, the dynamic damper has been used as a dynamic damper for a drive shaft of an automotive vehicle.
Such a conventional dynamic damper is installed onto the rod member such that the dynamic damper is disposed radially outwardly of the rod member. Therefore, the conventional dynamic damper is likely to interfere with other components disposed in the vicinity of the drive shaft, resulting in a limitation of the space for accommodating the dynamic damper. That is, the cylindrical dynamic damper is required to be made compact in its outside diameter.
Meanwhile, the cylindrical dynamic damper needs to have a sufficiently large mass of the metallic mass member, in order to effectively exhibit a desired vibration damping effect thereof. If the dynamic damper is made compact in size, however, the metallic mass member is accordingly made small in size, leading to difficulty in obtaining the desired mass of the metallic mass member. This results in deterioration of the vibration damping effect of the dynamic damper. Thus, the conventional dynamic damper has difficulty in meeting this downsizing requirement, sufficiently.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a dynamic damper which is novel in construction and compact in overall size, while having a sufficiently large mass of a metallic mass member.
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 those modes of the invention and combinations of the technical features, but may otherwise be recognized based on the thought of the present invention that disclosed 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 dynamic damper mounted on a rod-shaped oscillating member, including: (a) a generally cylindrical metallic mass member formed of sintered metal or forging, and disposed radially outwardly of the oscillating member; (b) a pair of elastic support members which are formed on and extends axially outwardly and radially inwardly from axially opposite sides of the metallic mass member so as to have a tapered cylindrical configuration, the pair of elastic support members being adapted to elastically support the metallic mass member with respect to the rod-shaped oscillating member; and (c) an elastic covering layer integrally formed with the pair of elastic support members and being fixed in close contact with a substantially entire area of a surface of the metallic mass member for covering the substantially entire area of the surface of the metallic mass member, the metallic mass member having bevels in the form of tapered cylindrical surfaces, which are formed at radially inner edges of axially opposite end faces of the metallic mass member, respectively, each of the bevels extending over a corresponding one of the axially opposite end faces and an inner circumferential surface of the metallic mass member, to thereby chamfer the corresponding one of the radially inner edges, the pair of elastic support members are fixed at large diameter end portions thereof to the bevels, respectively.
In the dynamic damper constructed according to the above mode (1) of the present invention, the radially inner edges of the axially opposite end faces of the metallic mass member are chamfered to provide therein the bevels, and the pair of elastic support members are fixed at their large diameter end portions to the bevels, respectively. This arrangement permits that the large diameter end portions, i.e., the axially inner end portions of the elastic support members protrudes substantially axially inwardly from the opposite axial end faces of the metallic mass member, respectively, by a given axial distance which corresponds to the axial length of the bevels. This makes it possible to enlarge the axial length of the metallic mass member, thereby effectively assuring a sufficiently large mass of the metallic mass member, while permitting axially inward extension of the elastic support members from the respective axial end faces of the metallic mass member, thereby assuring a desired effective free length of the elastic support members. This arrangement also permits a decrease in the axial length of a part of each elastic support member which part protrudes axially outwardly from the corresponding axial end face of the metallic mass member, whereby the dynamic damper as a whole can be made compact in its axial length. Accordingly, the dynamic damper of this mode of the invention can meet compatibly both requirements for the sufficiently large mass of the metallic mass member and for the sufficiently reduced size of the overall dynamic damper, which are only alternatively achieved in the conventional dynamic damper.
In the dynamic damper according to this mode of the invention, the axially inner portions of the elastic support members, which are likely to suffer from the stress concentration upon application of the vibrational load to the damper, are secured to the bevels formed at radially inner edges of the axially opposite end faces of the metallic mass member, thereby effectively easing or relaxing the stress concentration generated in the axially inner portions of the elastic support members. Described in detail, the conventional dynamic damper including the cylindrical metallic mass member and the two elastic support members which are formed axially opposite sides of the metallic mass member for elastically supporting the metallic mass member, is likely to suffer from a stress concentration generated at or near a boundary between elastic support members and the axially opposite end faces of the metallic
Lavinder Jack
Rossi & Associates
Tokai Rubber Industries Ltd.
Williams Thomas J.
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