Joints and connections – Flexibly connected rigid members – Elastomer interposed between radially spaced members
Reexamination Certificate
2002-01-23
2004-08-31
MacArthur, Victor (Department: 3679)
Joints and connections
Flexibly connected rigid members
Elastomer interposed between radially spaced members
C403S220000, C403S221000, C403S226000, C403S228000, C074S473290, C074S543000
Reexamination Certificate
active
06783297
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a shift lever bush which is mounted between a shaft portion formed in one of a pair of axially two-piece-divided shift lever members and a cylindrical portion formed in the other shift lever member.
2. Description of the Prior Art
There is a previously known shift lever bush of the type which is mounted between a shaft portion formed in one of a pair of axially (substantially vertically) two-piece-divided shift lever members (for example one located on the transmission side) and a cylindrical portion formed in the other shift lever member (for example another located on the shift knob side). This type of shift lever bush is intended for preventing the transfer of vibrations from the transmission side to the shift knob side.
For example, Japanese Utility Model Registration No. 2569721 Gazette discloses a shift lever bush. This shift lever bush includes: an inner cylindrical body which is mounted to a shaft portion of one of shift lever members by external interfit; an outer cylindrical body which is so disposed substantially coaxially with the cylinder axis of the inner cylindrical body as to surround an outer peripheral surface of the inner cylindrical body and which is mounted to a cylindrical portion of the other shift lever member by internal interfit; and a rubber elastic body, disposed between the inner cylindrical body and the outer cylindrical body, for connecting together these inner and outer cylindrical bodies. In the shift lever bush disclosed in the aforementioned gazette, the rubber elastic body is provided with an annular groove portion which opens to its cylinder axis direction end surface, which groove portion interfits with an annular stopper member. Further, a recessed portion is formed in a peripheral lateral surface of the groove portion on the outer cylindrical body side and, in addition, a projecting portion engageable with the recessed portion is formed in the stopper member. There is defined a clearance of a given amount between these projecting and recessed portions. Because of such arrangement, when the shift lever member on the shift knob side receives an operation load caused by a shift operation or select operation of the shift lever, relative displacement between the inner cylindrical body and the outer cylindrical body will not be regulated until the recessed portion of the groove portion and the projecting portion of the stopper member abut with each other. However, after the recessed portion and the projecting portion have engaged with each other, both relative displacement between the inner cylindrical body and the outer cylindrical body around the cylinder axis (displacement in the torsional direction) and relative displacement between the inner cylindrical body and the outer cylindrical body in a radial direction rectangular to the cylinder axis (displacement in the direction rectangular to the cylinder axis) are limited. Therefore, the spring characteristic of the shift lever bush disclosed in the aforementioned gazette is a two-stage characteristic for the torsional direction and for the direction rectangular to the cylinder axis with respect to its displacement amount.
However, in addition to the inner cylindrical body, the outer cylindrical body, and the rubber elastic body, the shift lever bush of the aforementioned gazette further requires the stopper member in order that its spring characteristic may have a two-stage characteristic, which results in the increase in component count. Besides, in this conventional shift lever bush, there is provided a stopper mechanism for placing and fixing the stopper member within the groove portion. This makes the construction complicated. As a result, the shift lever bush of the aforementioned gazette suffers inconveniences such as the increase in component count which results in the increase in manufacturing cost.
Further, the manufacture of the shift lever bush shown in the aforesaid gazette requires: firstly a step of performing integral vulcanization molding of the inner cylindrical body, the outer cylindrical body, and the rubber elastic body; a step of inserting, after locating the recessed portion of the groove portion and the projecting portion of the stopper member so as to circumferentially conform with each other, the stopper member into the groove portion; and a step of bending an opening edge of the inner cylindrical body and then bringing the opening edge portion into abutment with the stopper member to provide a stopper mechanism. Each step is extremely complicated and, besides, the number of steps is large, therefore producing such inconvenience that the manufacturing cost increases.
Bearing in mind the above-described circumstances, the present invention was made. Accordingly, an object of the present invention is to make it possible to manufacture a shift lever bush having a two-stage spring characteristic at lower cost.
SUMMARY OF THE INVENTION
In order to achieve the object, a first invention of the present application discloses a shift lever bush mounted between a shaft portion formed in one of a pair of axially two-piece-divided shift lever members and a cylindrical portion formed in the other of the pair of shift lever members. The shift lever bush of the first invention comprises: an inner cylindrical body mounted to the shaft portion of the one shift lever member by external interfit, an outer cylindrical body disposed substantially coaxially with a cylinder axis of the inner cylindrical body so as to surround an outer peripheral surface of the inner cylindrical body, and mounted to the cylindrical portion of the other shift lever member by internal interfit; and a rubber elastic body, fixedly attached to the outer peripheral surface of the inner cylindrical body, for connecting together the inner and outer cylindrical bodies. Further, an interfit fixing portion which is fixed to an inner peripheral surface of the outer cylindrical body by internal interfit and at least one projecting portion which becomes radially convex from the inner cylindrical body toward the outer cylindrical body are formed in the rubber elastic body, wherein the interfit fixing portion and the projecting portion are located at different positions in the cylinder axis direction, and a recessed portion, which becomes concave correspondingly to the shape of the projecting portion with a clearance of a given amount left between the recessed portion and the projecting portion, is formed at a position of the inner peripheral surface of the outer cylindrical body corresponding to the position of the projecting portion.
As a result of such arrangement, the inner cylindrical body mounted, by external interfit, to the shaft portion of one of the pair of shift lever members and the outer cylindrical body mounted, by internal interfit, to the cylindrical portion of the other shift lever member are interconnected at the interfit fixing portion formed in the rubber elastic body. Therefore, relative displacement between the inner cylindrical body and the outer cylindrical body in the cylinder axis direction is regulated by the interfit fixing portion. Accordingly, the spring characteristic of the shift lever bush in the cylinder axis direction becomes soft by making the length of the interfit fixing portion in the cylinder axis direction relatively short. As a result of making the spring characteristic of the shift lever bush in the cylinder axis direction soft, it becomes possible to impede the transfer of vibrations from the transmission side to the shift knob side, thereby achieving an excellent vibration proof effect.
On the other hand, when the shift lever member on the shift knob side receives an operation load caused by a shift operation or select operation of the shift lever, the inner cylindrical body and the outer cylindrical body will relatively rotate about the cylinder axis (the inner cylindrical body and the outer cylindrical body are twisted relative to each other) or will relatively be displaced in the radial dir
Hashimoto Osamu
Hiraiwa Yoshihito
Nishikawa Kenji
Kurashiki Kako Co., Ltd.
MacArthur Victor
Nixon Peabody LLC
Studebaker Donald R.
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