Rotary shafts – gudgeons – housings – and flexible couplings for ro – Housing – Flexible housing
Reexamination Certificate
2000-04-27
2001-09-25
Browne, Lynne H. (Department: 3629)
Rotary shafts, gudgeons, housings, and flexible couplings for ro
Housing
Flexible housing
C464S175000, C277S636000
Reexamination Certificate
active
06293873
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a universal joint, for example, which is used in a propeller shaft and a drive shaft of a vehicle, and which is provided with a boot disposed between an inner and an outer element of the universal joint, sealing and holding lubricant such grease or the like therewithin and preventing dust, water or the like from entering from the outside.
2. Description of the Related Art
Regarding a conventional universal joint provided with a boot, there is, for example, a structure described in Japanese Patent Application Laid-Open (JP-A) No. 9-14284. The universal joint ‘a’ described in this publication is a tripod type uniform joint which is used in a drive shaft of a vehicle, and is provided with a cylindrical outer ‘b’ and an inner ‘c’ fitted into the outer ‘b’, as shown in FIG.
12
.
The inner ‘c’ is provided with a drive shaft ‘d’, a ring-like member which is mounted to an end portion of the drive shaft ‘d’ and three rollers ‘e’ which are rotatably supported to three support shafts extending from the ring-like member outward in a diametrical direction and arranged in a peripheral direction at a uniform interval, respectively. Further, three guide grooves which are formed for respectively receiving three rollers ‘e’ of the inner ‘c’ along an axial direction are provided in an inner periphery of the outer ‘b’. Then, a torque is transmitted between the inner ‘c’ and the outer ‘b’ via three rollers ‘e’ which are engaged with the guide grooves.
On the contrary, a boot ‘f’ mounted between the inner ‘c’ and the outer ‘b’ of the universal joint ‘a’ is constituted by a cylindrical boot metal fitting ‘g’ and a flexible elastic body ‘h’ fixed to one end portion of the boot metal fitting ‘g’. The boot metal fitting ‘g’ is fitted to an outer periphery of the outer ‘b’ and the elastic body ‘h’ is fitted to an outer periphery of the drive shaft ‘d’. An O-ring ‘i’ is attached to a groove formed in the fitting portion of the outer ‘b’. In the manner mentioned above, the inside of the joint is kept airtight by the boot ‘f’ to prevent the lubricant charged therewithin from leaking out and dust, water or the like from entering thereinto.
In this case, in the prior art mentioned above, when inserting the inner ‘c’ to which the boot ‘f’ is fitted into the inside of the outer ‘b’ so as to assemble the inner ‘c’ and the outer ‘b’, the boot metal fitting ‘g’ is fitted to the outer periphery of the outer ‘b’. At this time, since the air within the boot ‘f’ is not taken out while the inner periphery of the boot metal fitting ‘g’ is brought into contact with the O-ring ‘i’, the portion between the boot metal fitting ‘g’ and the outer ‘b’ is sealed by the O-ring ‘i’, and when the boot metal fitting ‘g’ is further inserted to reach the final fitting position, the air is compressed and the pressure thereof is increased. As a result, the elastic body ‘h’ is expanded in a manner shown by a double dot chain line in
FIG. 12
due to the increased air pressure.
In the case that the elastic body ‘h’ is used in this state, the elastic body ‘h’ and the drive shaft ‘d’ may rub against each other when the inner ‘c’ and the outer ‘b’ relatively move in an axial direction, and an angle formed by an axis of the outer ‘b’ and an axis of the inner ‘c’ changes, so that durability of the boot ‘f’ is deteriorated. Further, since the elastic body ‘h’ is expanded when the sealed air is expanded due to a centrifugal force of the grease during rotation of the universal joint ‘a’ and a temperature increase, the elastic body ‘h’ and the inner ‘c’ rub against each other under a stronger force.
Then, in order to avoid the matter mentioned above, an air pressure adjusting operation may be performed for taking out the air sealed and pressurized within the boot ‘f’ after the fitting operation between the boot metal fitting ‘g’ and the outer ‘b’ is completed, and the assembly between the inner ‘c’ and the outer ‘b’ is completed. This air pressure adjusting operation is performed, for example, by inserting a tool into the fitting portion between the elastic body ‘h’ and the drive shaft ‘d’, thereby forming an interval for communicating the inside of the boot ‘f’ with the open air between the both so as to discharge the air within the boot to the open air.
However, since the adjusting operation not only increases the process and labor of assembling the universal joint but also damages the boot ‘f’ during the adjusting operation, the adjusting operation must be performed very carefully. Because of the care required, there is generated a reduction of efficiency of the operation of assembling the universal joint ‘a’.
SUMMARY OF THE INVENTION
The present invention is made by taking the matter mentioned above into consideration, and setting as one object of the present invention to improve efficiency of an operation of assembling a universal joint by adjusting a pressure of air within a boot during the universal joint assembly.
In accordance with the present application, there is provided a universal joint comprising: an inner and an outer element which are assembled with each other; and a boot which has one end fitted to the inner and the other end fitted to the outer so as to seal between the inner and the outer, wherein a communication passage which causes insides of the boot and the open air to communicate with each other until the outer is positioned at a location near a fitting operation completing position from a fitting operation starting position. This shuts communication with the insides of the boot and the open air when the outer is positioned at the fitting operation completing position, in a fitting portion between the outer and the boot.
In this case, in this specification, the position near the fitting operation completing position of the outer means a position at which the communication passage is closed, and the boot is not expanded or is only slightly expanded in accordance with the pressure increase of the air within the boot caused by the relative movement. This is so even when the outer moves to the fitting operation completing position with respect to the boot. Also, there is not generated a disadvantage that the boot and the inner rub against each other as mentioned in the prior art, and only a slight expansion is generated. Further, in this specification, circles such as a cylinder, a ring, a circumference, a circular arc and the like include not only a severe circular shape but also a substantially circular shape corresponding to a shape approximating a circle.
REFERENCES:
patent: 3204427 (1965-09-01), Dunn
patent: 3362193 (1968-01-01), Ritsema
patent: 3468171 (1969-09-01), Macielinski
patent: 3583244 (1971-06-01), Teinert
patent: 4556400 (1985-12-01), Krude et al.
patent: 4557491 (1985-12-01), Orain
patent: 4747805 (1988-05-01), Welschof et al.
patent: 4767381 (1988-08-01), Brown et al.
patent: 5176576 (1993-01-01), Moulindt
patent: 5183351 (1993-02-01), Schneider
patent: 5230660 (1993-07-01), Warnke
patent: 5297996 (1994-03-01), Dragna
patent: 5451186 (1995-09-01), Poulin et al.
patent: 6093108 (2000-07-01), Moulinet
patent: 6179717 (2001-01-01), Schwarzler
patent: HEI742987 (1995-05-01), None
patent: HEI828704 (1996-02-01), None
patent: HEI914284 (1997-01-01), None
Haneishi Kazunobu
Hiraga Yoshio
Iwano Kazuhiro
Browne Lynne H.
Orum & Roth
Showa Corporation
Thompson Kenn
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