Automotive shock absorbing propeller shaft apparatus

1. An automotive shock absorbing propeller shaft apparatus comprising:

a first yoke stub provided in an end portion of a first propeller shaft and a second yoke stub provided in an end portion of a second propeller shaft, being coupled to each other by a cross pin so as to be bendable with each other, the first and second propeller shafts being coupled;

at least one of the first and second propeller shafts being supported to an inner ring of a rubber-like elastic member via a bearing, the rubber-like elastic member being supported to a bracket in a vehicle body side; and

the first propeller shaft compressing the second propeller shaft in an axial direction so as to be capable of rupturing a shock absorbing portion when the first and second propeller shafts are contracted by being exposed to an impact force,

the first yoke stub being provided with a fork-shaped protruding portion protruding in an axial direction from both sides of a first base portion and receiving one pin forming a cross shape of the cross pin,

the second yoke stub being provided with a fork-shaped protruding portion protruding in an axial direction from both sides of a second base portion and receiving the other pin forming the cross shape of the cross pin, such that when the first and second yoke stubs are bent to a fixed maximum bending angle with each other via the cross pin, bending angle control portions coming into collision with each other are provided in shoulder surfaces of the fork-shaped protruding portions opposing to each other in the axial direction,

wherein each of the first and second yoke stubs is structured such that a base end side rising up from the base portion is set to a wide portion, and a leading end side along an upper half periphery of the pin hole is set to a narrow portion, in each of the fork-shaped protruding portions in both sides of the base portion, and a step-like shoulder surface is provided in a portion forming a boundary between the wide portion and the narrow portion in both sides approximately sandwiching a center of the pin hole.

2. An automotive shock absorbing propeller shaft apparatus as claimed in claim 1 , wherein each of the bending angle control portions of the fork-shaped protruding portions of the first and second yoke stubs is formed by a shoulder surface forming a down slope from the side of the narrow portion toward the side of the wide portion at an angle corresponding to the maximum bending angle with respect to a horizontal surface which is orthogonal to a center shaft of the first yoke stub, in a front elevational view of the fork-shaped protruding portion and a pin hole.

3. An automotive shock absorbing propeller shaft apparatus comprising:

a first yoke stub provided in an end portion of a first propeller shaft and a second yoke stub provided in an end portion of a second propeller shaft, being coupled to each other by a cross pin so as to be bendable with each other, the first and second propeller shafts being coupled;

at least one of the first and second propeller shafts being supported to an inner ring of a rubber-like elastic member via a bearing, the rubber-like elastic member being supported to a bracket in a vehicle body side; and

the first propeller shaft compressing the second propeller shaft in an axial direction so as to be capable of rupturing a shock absorbing portion when the first and second propeller shafts are contracted by being exposed to an impact force,

the first yoke stub being provided with a fork-shaped protruding portion protruding in an axial direction from both sides of a first base portion and receiving one pin forming a cross shape of the cross pin,

the second yoke stub being provided with a fork-shaped protruding portion protruding in an axial direction from both sides of a second base portion and receiving the other pin forming the cross shape of the cross pin, such that when the first and second yoke stubs are bent to a fixed maximum bending angle with each other via the cross pin, bending angle control portions coming into collision with each other are provided in shoulder surfaces of the fork-shaped protruding portions opposing to each other in the axial direction, the bending angle control portions which come into collision with each other are provided in the fork-shaped protruding portions of the first and second yoke stubs and are structured such as to come into collision with each other via surface contact with each other,

wherein each of the first and second yoke stubs is structured such that a base end side rising up from the base portion is set to a wide portion, and a leading end side along an upper half periphery of the pin hole is set to a narrow portion, in each of the fork-shaped protruding portions in both sides of the base portion, and a step-like shoulder surface is provided in a portion forming a boundary between the wide portion and the narrow portion in both sides approximately sandwiching a center of the pin hole.

4. An automotive shock absorbing propeller shaft apparatus as claimed in claim 3 , wherein each of the bending angle control portions of the fork-shaped protruding portions of the first and second yoke stubs is formed by a shoulder surface forming a down slope from the side of the narrow portion toward the side of the wide portion at an angle corresponding to the maximum bending angle with respect to a horizontal surface which is orthogonal to a center shaft of the first yoke stub, in a front elevational view of the fork-shaped protruding portion and a pin hole.