Rotary shafts – gudgeons – housings – and flexible couplings for ro – Torque transmitted via flexible element – Nonmetallic element
Reexamination Certificate
1999-05-27
2001-08-07
Browne, Lynne H. (Department: 3629)
Rotary shafts, gudgeons, housings, and flexible couplings for ro
Torque transmitted via flexible element
Nonmetallic element
C074S492000, C403S290000, C403S057000, C464S180000
Reexamination Certificate
active
06270418
ABSTRACT:
This application claims the benefits of Japanese Application Nos. 10-163276, 11-046551 and 11-085415 which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an elastic shaft joint which is assembled into a universal joint for constituting, for example, a steering apparatus for a car so as to transmit a motion of a steering wheel to a steering gear and to prevent a vibration on the side of the steering gear from being transmitted to the steering wheel.
2. Related Background Art
A steering apparatus for a car is arranged to transmit a motion of a steering shaft which is rotated by a steering wheel to a steering gear so as to give a steering angle to the wheels. Normally, the steering shaft and the input shaft of the steering gear can not be disposed on the same straight line. For this reason, a universal joint is arranged between the steering shaft and the input shaft to transmit a motion of the steering wheel to the steering gear. A vibration absorbing ability is conventionally given to the universal joint, in order to prevent the vibration which is transmitted from the wheels to the steering gear when the car is run from further being transmitted to the steering wheel to give unpleasant feeling to the driver. In order to give the vibration absorbing capability to the universal joint in this manner, an elastic material such as rubber is usually assembled into this universal joint so that the transmission of the vibration is prevented by use of the elastic material.
As such an elastic shaft joint or a universal joint assembling such elastic shaft joint therein, there are conventionally known joints disclosed in Japanese Patent Application Laid-Open Nos. 56-39325 (French Patent Application Laid-Open No. 2464404), 56-131831, 60-184716 to 60-184718, 60-215122, and 60-215123, 61-201924, Japanese Utility Model Application Laid-Open Nos. 54-82257, 5-83462, and 5-89964, French Patent Application Laid-Open No. 2614985, U.S. Pat. No. 4,509,775, etc.
In the elastic shaft joint conventionally known, leaving the case in which a vibration in the direction of rotation of the shaft such as a steering shaft is applied, when a vibration in the axial direction of this shaft is applied, the capacity of the shaft joint to attenuate this vibration is poor, so that the vibration in the axial direction is easily transmitted to the steering wheel. Especially, when a displacement along the axial direction is applied to a part with a shaft mounted thereon, for example, when the distance between the steering gear and the front end portion of the steering shaft is changed due to a vibration upon running of the car, this displacement can not be absorbed. Also, if it is required to absorb a tolerance in manufacturing or assembling the parts when the elastic shaft joint is to be assembled into a steering apparatus of the car, such requirement can not be satisfied. Further, when one end portion of the shaft with the elastic shaft joint assembled therein is inserted in the base end portion of a yoke of a universal joint in the axial direction thereof, this end portion of the shaft is required to be displaced in the axial direction, which also can not be satisfied.
Taking these circumstances into account, such a structure as disclosed in, for example, Japanese Patent Application Laid-Open No. 11-048991 is contrived in which a shaft is divided into a pair of elements and the paired. elements are brought into serration engagement with each other at a coupling portion thereof. Since the portion of the serration engagement between the paired elements allows a large displacement in the axial direction, even when a displacement in the axial direction is applied onto a portion with the shaft mounted thereon upon running of the car, this displacement is absorbed. If a tolerance in manufacturing or assembling of the parts is required to be absorbed when the elastic shaft joint is to be assembled into the steering apparatus of the car, it is possible to prevent such tolerance. Further, when one end portion of the shaft with the elastic shaft joint mounted thereon is to be inserted into the base end portion of the yoke of the universal joint in the axial direction, it is possible to displace this end portion of the shaft in the axial direction.
However, the cost is inevitably increased when the serration engagement portion is provided in a part of the shaft. That is, in order to prevent a backlash of the serration engagement portion, irrespective of presence or absence of vibration in running, it is required to form a slit on the side of an outer shaft on which a highly accurate processing is performed or a female serration is formed, for elastically expanding or contracting the diameter of this outer shaft. Further, it is required to provide a member for elastically contracting the diameter of the outer shaft.
SUMMARY OF THE INVENTION
Taking these circumstances into consideration, an object of the present invention is to provide a practical elastic shaft joint which is capable of absorbing a displacement in the axial direction and securing a sufficient durability though manufactured comparatively at a low cost.
The elastic shaft joint of the present invention is to couple an end portion of a rotatable shaft such as a steering shaft and a rotary member which rotates upon rotation of such shaft, such as a yoke for constituting a universal joint, so as to absorb a certain displacement in the axial direction of the direction of rotation.
Out of such elastic shaft joints of the present invention, an elastic shaft joint according to a first aspect of the invention has a pair of outer-diameter side engagement surfaces which are substantially parallel to each other at two positions on the opposite sides of the outer peripheral surface in the radial direction. The rotary member is provided with a pair of restraint plate portions which are substantially parallel to each other and is formed to have an opening on a lateral side thereof. Then, a vibration absorbing member is provided between the rotary member and the shaft. Then, this vibration absorbing member is constituted by an elastic member which is disposed on the inner peripheral surface of a part fixed to the rotary member and a sliding sleeve which is supported by the inner peripheral surface of this elastic member, which inner peripheral surface is brought into slidable contact with the outer peripheral surface of the shaft.
An elastic shaft joint according to a second aspect of the present invention is provided with a coupling sleeve around one end of the shaft, to allow free displacement of this shaft in the axial direction and to freely absorb a vibration to be transmitted to or from this shaft. Of the rotary member, the base portion, to which an end portion of the shaft is to be coupled and fixed, is formed to have an opening on the lateral side thereof. Then, this coupling sleeve is coupled and fixed to this rotary member to form the elastic shaft joint by inserting the coupling sleeve into this base portion from the lateral opening so as to suppress the coupling sleeve by means of this base portion.
Further, an elastic shaft joint according to a third aspect of the present invention is provided with a pair of outer-diameter side engagement surfaces which are substantially parallel to each other at two positions on the opposite sides of the outer peripheral surface in the radial direction of at least one end portion of the shaft.
A coupling sleeve is disposed in the vicinity of an end portion of the shaft. Then, rotation limiting cylinders are provided at two positions on the inner peripheral surface on the opposite sides in the radial direction, in a half part of this coupling sleeve in the axial direction which is a part closer to the end portion of this shaft. Each of these rotation limiting cylinders is provided with inner-diameter side engagement surfaces which are substantially parallel to each other and face the above-mentioned outer-diameter side engagement surfaces with a gap therebetw
Minamigata Takahiro
Oka Shoji
Browne Lynne H.
Miles & Stockbridge P.C.
NSK Ltd.
Thompson Kenneth
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