Shock-absorbing mechanism for power-transmission device

#The present invention relates to a shock-absorbing mechanism for a power-transmission device or propeller shaft for motor vehicles, and more particularly, to the shock-absorbing mechanism for absorbing an input load acting axially on the propeller shaft upon vehicle collision.

#A typical shock-absorbing mechanism for a power-transmission device of this type is disclosed in JP-A 10-250390. This shock-absorbing mechanism is applied to a propeller shaft for motor vehicles, wherein the propeller shaft comprises a first shaft on the transmission side and a second shaft on the driving-wheel side, which are coupled together through a tripod universal joint. A rear end of the first shaft is formed with an outer race of the universal joint, whereas an end of the second shaft on the first-shaft side is formed with an inner shank having a front end arranged through the outer race.

#The outer race is formed like a bottomed cylinder, wherein an opening opposite to a bottom wall is covered with an annular member and a boot, and an annular groove is formed in the outside face of the bottom wall. The inner shank is rotatably supported-to a vehicle body through a center bearing, and has a tripod arranged protuberantly at the outer periphery of the front end and positioned by an annular protrusion. The tripod is slidably engaged with three grooves formed in the inner peripheral face of the outer race, thus configuring the universal joint. The center bearing has a stepped cylindrical support member arranged at the outer periphery. An annular elastic body is integrated with the outer peripheral face of the support member.

#The other objects and features of the present invention will become apparent from the following description with reference to the accompanying drawings, wherein:

#FIG. 1 is a longitudinal sectional view showing an upper half of a first embodiment of a shock-absorbing mechanism for a motor vehicle according to the present invention;

#FIG. 2 is a view similar to FIG. 1, explaining operation of the first embodiment upon vehicle collision;

#Referring to the drawings, a description is made about a shock-absorbing mechanism for a power-transmission device for motor vehicles embodying the present invention. In the illustrative embodiments, the power-transmission device includes a propeller shaft 1.

#Referring to FIG. 1, propeller shaft 1 comprises essentially a driving shaft or first shaft 2 on the transmission side coupled to a transmission, a driven shaft or second shaft 3 on the driving-wheel side coupled axially to driving-side shaft 2 through a constant-velocity joint or slide bearing 4, and a center bearing 5 for rotatably supporting to a vehicle body an end of driving-side shaft 2 on the driven-side shaft 2 side. Constant-velocity joint 4 and center bearing 5 are disposed adjacent to each other at a short distance so as to fully reduce vehicle noise and vibration due to rotation of propeller shaft 1.

#Driving-side shaft 2 comprises a tubular main body 6 on the transmission side and a stepped small-diameter stub axle 6a coupled axially to one end of main body 6 by friction welding. A small-diameter portion of stub axle 6a at the front end is arranged through driven-side shaft 2, constituting part of constant-velocity joint 4.