Spring devices – Resilient shock or vibration absorber – Nonmetallic – resilient element
Reexamination Certificate
2001-01-31
2002-09-17
Lavinder, Jack (Department: 3683)
Spring devices
Resilient shock or vibration absorber
Nonmetallic, resilient element
C267S141200, C188S379000
Reexamination Certificate
active
06450487
ABSTRACT:
This application is based on Japanese Patent Application No. 2000-285750 filed Sep. 20, 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 power transmitting members 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 JPA-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.
In the conventional dynamic damper, the mass member is generally formed of a carbon steel by casting, or alternatively is formed by roll molding performed on a metal plate, since these materials are available at a relatively low cost and has a relatively large mass. The elastic support members are bonded to the mass member in the process of vulcanization of a rubber material for forming the elastic support member.
The conventional dynamic damper constructed as described above requires an adhesion treatment, e.g., an application of the adhesive on the circumferential surface of the mass member, upon bonding the elastic support member to respective portions of the mass member in the above-indicated vulcanization of the material. This may cause deterioration in terms of efficiency and cost of manufacture of the dynamic damper.
In the light of these drawbacks of the conventional dynamic damper, it is considered to modify the conventional dynamic damper to comprise an elastic covering layer which is integrally formed with the elastic support members so as to cover substantially entire area of the outer surface of the mass member, so that the mass member is fixed to the elastic support member without using the adhesion applied between the elastic support member and the mass member. However, the omission of the adhesive treatment leads to difficulty in attaining practically sufficient fixing or bonding strength between the elastic support members and the mass member. Described in detail, the elastic support members and the mass member which are not bonded with each other via the adhesive layer, are likely to be displaced relative to each other at the interface therebetween upon application of a relatively large vibrational load to the dynamic damper. This may possibly cause deterioration of vibration damping effect of the dynamic damper.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a dynamic damper which is novel in construction and which permits a high fixing or bonding strength between a metallic mass member and an elastic support member with no adhesive treatment performed on the 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 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 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 formed on and extending axially outwardly from axially opposite sides of the metallic mass member 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 without using an adhesive, for covering the substantially entire area of the surface of the metallic mass member, the metallic mass member having at least two slits extending through a wall thickness thereof, the at least two slits being open in and extending axially inwardly from axially opposite end faces of the metallic mass member, respectively, and being filled with the elastic covering layer, the metallic mass member further having inclined planes formed at radially inner edges of circumferentially opposite open-end edge portions of each of the at least two slits, each of the inclined planes extending over an inner surface of the corresponding slit, the corresponding axial end face of the metallic mass member and the inner circumferential surface of the metallic mass member, to chamfer the radially inner edge of the corresponding open-end edge portion.
In the dynamic damper constructed according to the above mode (1) of the present invention, the metallic mass member is formed of sintered metal or forging. This arrangement permits a relatively high level of surface roughness of the metallic mass member of the dynamic damper of the present invention in comparison with a metallic mass member formed by casting or pressing. Accordingly, the elastic covering layer fixed in close contact with the rugged surface of the metallic mass member is firmly secured to the metallic mass member owing to a mechanical fixing force caused by engagement of the rugged surface of the metallic mass member with the inner surface of the elastic covering layer which is rugged corresponding to the rugged surface of the metallic mass member upon vulcanization of a rubber material to form the elastic covering layer, resulting in elimination of the adhesive treatment. Various kinds of known sintered metallic materials, including pure iron type, iron-carbon type, and iron-copper type, may be employed for the metallic mass member of the dynamic damper of the present invention, taking into account the required mass of the metallic mass member, the manufacturing cost, working conditions of the dynamic damper and the like. Further, various kinds of known forging or forged members, such as a carbon steel may be used as the metallic mass member, and the metallic mass member may be formed by hot forging or alternatively by cold forging. The employed forging should be subjected to a scale removal t
Lavinder Jack
Rossi & Associates
Sy Mariano
Tokai Rubber Industries Ltd.
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