A Collapsible driveshaft assembly that has a relatively low collapse force rating and that does not have a reduced torque carrying capacity includes an inner tube that is received within an outer tube in a press fit relationship.
The inner tube is disposed within the outer tube such that a predetermined amount of overlap is formed between the two tubes. A mechanical interlock is formed in the overlapped region for increasing the total frictional force between the inner tube and the outer tube as well as for increasing the torque carrying capacity of the driveshaft tube.
The mechanical interlock can be formed using one or more crimps which are disposed in the overlapped region. The length of the overlapped region, the number of crimps and the crimp configuration are a function of a number of factors including the torque requirements of the driveshaft tube, the sizes of the inner tube and the outer tube, and the material chosen for the driveshaft tube.
Preferably, the crimps extend around the entire perimeter of the overlapped region in a spaced-apart fashion. The crimps can be formed having any shape and length. Preferably, the crimps have an elongated, generally oval shape and a length which is less than about one-third the total length of the overlapped region.
Collapsible Driveshaft Standards A vehicle’s driving shaft has to be designed to meet high standards for the following performance metrics:
Durability Shear Stress and Vibration Warping when Exposed to Temperature Extremes Torque Transmission Efficiency Usually, joints connect several propeller shaft components when the shaft has to be relatively long.
Collapsible Driveshaft Joints
There are several prominent joint designs for propeller shafts. The most common are universal and constant-velocity joints. Universal joints have the advantage of allowing two components of a propeller shaft to pivot through a wide angle. This is advantageous in complicated machinery where the line between an engine/transmission and the differential is blocked by other components.
Constant-velocity joints are specially designed to maintain constant rotation speed between two components of the driving shaft, even at significant angles. Universal joints generate vibration and angular momentum discrepancies if deviation angle becomes large enough. Joint design can be as important as the driveshaft itself.
Considerations As with everything, cost/performance tradeoffs are inevitable in drive shaft selection and repair. Constant-velocity joints are more expensive than universal joints but are usually worth the price in efficiency and durability. Drive shafts can be severely degraded by vibrations and improper joint alignment. Sudden braking/acceleration can also reduce driveshaft lifetime since doing so puts stress on the shaft, joint components and differential gears.
