Spring devices – Resilient shock or vibration absorber – Nonmetallic – resilient element
Reexamination Certificate
2000-06-16
2002-12-31
Lavinder, Jack (Department: 3683)
Spring devices
Resilient shock or vibration absorber
Nonmetallic, resilient element
C267S141200, C188S379000
Reexamination Certificate
active
06499730
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a dynamic damper having a generally cylindrical shape, and installed on a hollow or a solid rod member which is subject to oscillation and which is a member of a vibration transmitting system such as shafts, arms, or conduits used in various devices, for reducing or absorbing vibrations of the oscillating rod member, and further relates to a method of producing the dynamic damper.
2. Description of the Related Art
Various kinds of rod members such as shafts or arms functioning as a power transmitting members and such as conduit or pipes serving as a fluid passage generally tend to oscillate or vibrate and consequently resonate due to an external oscillating force. Further, the rod member undesirably transmits a vibration excited therein to 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 for preventing the resonance of the rod member and the transmission of the excited vibration of the rod member to the other components.
Examples of such a dynamic damper are disclosed in JP-A-2-190641, JP-B-6-037915, and JP-A-10-132027, wherein the dynamic damper has a mass member having a generally cylindrical configuration and an elastic support member secured to the mass member. The disclosed dynamic damper is installed onto an oscillating rod member and secured thereto at the elastic support member so that the mass member is elastically supported on the oscillating rod member via the elastic support member. The dynamic damper installed on the oscillating rod member as described above constitutes a secondary vibration system in which the mass member serves as a mass and the elastic support member serves as a spring, with respect to the oscillating rod member as a primary vibration system. The thus constructed dynamic damper is properly tuned so that the dynamic damper is capable of exhibiting effective damping characteristics with respect to a torsional or circumferential vibration as well as an axial and a radial vibration of the rod member. Since the mass member has the cylindrical shape, the mass member of the dynamic damper is not released from the rod member, even if the elastic support member is undesirably broken. In other words, the dynamic damper having the cylindrical mass member has a so-called “fail-safe” structure. For the above, the dynamic damper is considered to be installed on a drive shaft of an automotive vehicle for absorbing or reducing vibrations thereof, for example.
The conventional dynamic damper preferably comprises the mass member consisting of a cylindrical mass formed of a metallic material such as carbon steel, which is available at a relatively low cost and which has a relatively large mass and the elastic support member which is bonded to the cylindrical metallic mass member in the process of vulcanization of a rubber material for forming the elastic support member, with the mass coated by an adhesive material. The cylindrical metallic mass may be formed by casting a metallic material, by cutting a metallic piping member in a suitable length or by roll molding a metallic plate to form a cylindrical member.
However, the metallic mass prepared by casting has a low dimensional accuracy, resulting in difficulty in providing a desired mass of the metallic mass with high accuracy. Further, the metallic mass formed by casting suffers from a problem of difficulty in providing a desired high-specific gravity thereof and a problem of cumbersome manufacturing processes and post-treatments. On the other hand, the metallic mass formed of the metallic piping member by cutting in the suitable axial length, or the metallic mass formed of the metallic plate by pressing, e.g., by roll molding, may be produced with ease and with high-dimensional accuracy. However, such a metallic mass undesirably requires a significantly high-manufacturing cost due to the expensive piping member or undesirably required huge and expensive dies for the press.
In order to reduce the manufacturing cost of the dynamic damper, there is proposed to omit an adhesion treatment e.g., applying the adhesive between the elastic support member and the metallic mass. To this end, the dynamic damper may be modified to further comprise a rubber layer which is adapted to cover a substantially entire area of the outer surface of the metallic mass and integrally formed with the elastic support member, so that the elastic support member is fastened to the metallic mass without the above-indicated adhesion treatment. The thus constructed dynamic damper however, cannot provide resilient bonding strength between the elastic support member and the metallic mass, and it does not meet the requirements of the dynamic damper.
More specifically described, in the dynamic damper whose metallic mass and the elastic support member are not bonded together by means of the adhesive, the metallic mass and the elastic support members are likely to be displaced relative to each other at an interface therebetween, upon application of a relatively large vibrational load to the dynamic damper, leading to an undesirably introduction of the air into the interface between the metallic mass member and the elastic support member, resulting in deterioration of a vibration damping effect. The similar problem, that is the undesirable introduction of the air into the interface between the metallic mass and the elastic support member, may possibly occur, when the dynamic damper is installed on the oscillating rod member and a primary load in its axial direction is applied thereto, and when the dynamic damper is installed on a propeller shaft of the automobile vehicle and small pieces of rocks or curb stones collide with the dynamic damper, for example.
SUMMARY OF THE INVENTION
It is therefor a first object of this invention to provide a dynamic damper which has novel structure wherein a metallic mass member has a relatively high-specific gravity and is constructed with a high-dimensional accuracy, and wherein the metallic mass member and an elastic support member are fastened to each other with high strength. The dynamic damper also permits a desired damping effect with high stability and a reduced manufacturing cost.
It is therefore a second object of this invention to provide a method suitable for producing the dynamic damper having such a novel structure indicated above.
The first object may be achieved according to a first aspect of this invention which provides a dynamic damper mounted on a rod-shaped oscillating member, comprising: (a) a generally cylindrical mass member disposed radially outwardly of the oscillating member and comprising a cylindrical metallic mass which is formed b forging and which is subjected to a scale-removal treatment; (b) an elastic support member for elastically supporting the cylindrical metallic mass for connection thereof with the oscillating member; and (c) an elastic covering layer adapted to cover a substantially entire area of a surface of the cylindrical metallic mass and integrally formed with the elastic support member, the elastic covering layer being fixed in close contact with the substantially entire area of the surface of the cylindrical metallic mass so that the elastic support member is firmly secured to the cylindrical metallic mass without using an adhesive.
In the dynamic damper constructed according to the first aspect of the invention, the use of the cylindrical mass member in the form of the forged cylindrical metallic mass permits a higher dimensional accuracy and a higher specific gravity of the mass member, in comparison with the case where the mass member is formed of a metallic material by casting. In particular, the cylindrical metallic mass formed by forging has the surface rugged by the scale removal treatment. Therefore, the elastic covering layer covering the rugged surface of the cylindrical metallic mass is firmly secured to the metallic mass owing to a mechanical bonding strength caused by an
Kuwayama Naohito
Tanahashi Hiroaki
Lavinder Jack
Rossi & Associates
Sy Mariano
Tokai Rubber Industries Ltd.
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