Rotary shafts – gudgeons – housings – and flexible couplings for ro – Having heating or cooling means
Reexamination Certificate
2000-07-13
2001-11-27
Browne, Lynne H. (Department: 3629)
Rotary shafts, gudgeons, housings, and flexible couplings for ro
Having heating or cooling means
C403S032000
Reexamination Certificate
active
06322452
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates in general to a power transmission shaft unit for use in wheeled motor vehicles, and more particularly to a power transmission shaft unit such as propeller shaft unit, drive shaft unit or the like of the vehicle.
2. Description of the Prior Art
Some of the power transmission shaft units are of a type that comprises a universal coupling and a hollow connecting member which are connected in line. These two members have mating surfaces at their axial connecting ends. One of the mating surfaces is formed with an annular ridge that is coupled with an annular recess formed in the other of the mating surfaces, and the universal coupling and the hollow connecting member are joined with the aid of connecting bolts.
However, sometimes, the above-mentioned joining tends to cause the two joined members to constitute therebetween an isolated air space. Thus, under operation of the transmission shaft unit, heat inevitably produced in the universal coupling transmits to the isolated air space to heat and thus expand the air therein. However, the expansion of air tends to apply a marked stress to sealing members, such as a dust boot and the like, causing the sealing members to have an undesired permanent set. One of measures for solving this undesirable matter is to provide the isolated air space with an air discharge passage. This measure is described in Service Manual of MITSUBISHI PAJERO issued from MITSUBISHI MOTOR CO., in July, 1993.
However, even this measure has failed to provide a satisfied performance due to its inherent construction. That is, in this known measure, foreign matters, such as muddy water and the like tend to enter the enclosed space through the air discharge passage, which has an undesired influence on lubrication of friction parts in the shaft unit.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a power transmission shaft unit which is free of the above-mentioned drawback and superior to the above-mentioned known power transmission shaft unit.
According to a first aspect of the present invention, there is provided a power transmission shaft unit which comprises a universal coupling having a first contact surface; a hollow connecting member having a second contact surface; a coupling structure that connects the first and second contact surfaces in a manner to constitute an enclosed space that includes an interior of the universal coupling and that of the connecting member; and an air passage that extends between the enclosed space and an open air, the air passage being bent in shape.
According to a second aspect of the present invention, there is provided a power transmission shaft unit which comprises a universal coupling having a first contract surface, the universal coupling including spherical outer and inner rings, a plurality of balls, a spherical cage for rotatably holding the balls between the outer and inner rings, a stub shaft having a splined end engaged with a splined bore formed in the inner ring and a dust boot extending between the dust boot and the stub shaft, the first contact surface being defined by an annular flange provided by the outer ring; a hollow connecting member having at a diametrically enlarged end thereof a second contact surface; a coupling structure that connects the first and second contact surfaces in a manner to constitute an enclosed space that includes an interior of the universal coupling and that of the hollow connecting member; a dust cap disposed in the enclosed space to divide the same into first and second space portions, the first space portion being exposed to the interior of the coupling structure, the second space portion being exposed to the interior of the connecting member; an air breather provided by the dust cap, the air breather permitting an air flow from the first space portion to the second space portion; and an air passage that extends between the second space portion of the enclosed space and an open air, the air passage being bent in shape.
REFERENCES:
patent: 2432803 (1947-12-01), Rice
patent: 4887917 (1989-12-01), Troster et al.
patent: 5429552 (1995-07-01), Scherner et al.
patent: 5853250 (1998-12-01), Krude et al.
Service Manual of Mitsubishi Pajero, Mitsubishi Motor Co., Jul. 1993.
Binda Greg
Browne Lynne H.
Foley & Lardner
Unisia Jecs Corporation
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