Tripod Constant Velocity Joint Tapered Roller Friction Reduction
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Solution Overview
Problem
Conventional tripod type constant velocity joints experience significant frictional contact issues and shudder disturbances due to axial forces, particularly when transmitting large torque at large joint angles, leading to reduced durability and operational efficiency.
Innovation Solution
The implementation of a tapered roller structure in the inner and outer rollers, with a selected taper angle range of 2 tan−1(0.030/Lt) < θt < 2 tan−1(0.3556/P1), prevents self-separation and reduces friction by biasing the roller assembly towards the trunnion, allowing smooth operation and enhanced mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional cylindrical rollers are used in the tripod constant velocity joint, then the structure is simple and easy to manufacture, but significant frictional contact occurs between the rollers and side faces, causing shudder disturbances and reduced durability
Solution Approach 1:
The patent applies parameter changes by modifying the geometry of the rollers from cylindrical to tapered shape. The tapered rollers have a taper angle θ that varies along their length, allowing the contact area and pressure distribution to change dynamically during operation. This geometric parameter change reduces frictional contact between the rollers and side faces of the guide grooves, thereby reducing shudder disturbances and improving durability.
2Reliability
If conventional cylindrical rollers are used, then the manufacturing process is simple, but the rollers experience self-separation from the roller assembly under large torque conditions
Solution Approach 1:
The tapered roller design changes the geometric parameters of the rollers to include a taper angle θ. This parameter change creates a wedging effect that prevents self-separation of the rollers from the roller assembly under large torque conditions. The tapered shape allows the rollers to maintain proper positioning and engagement throughout the operating range, improving operational stability.
3Adaptability or versatility
If the joint operates with large joint angles, then the adaptability of the drive system is improved, but axial forces increase causing severe shudder disturbances
Solution Approach 1:
The tapered roller geometry changes the force distribution parameters within the joint. The taper angle θ allows the rollers to better accommodate large joint angles by distributing axial forces more evenly across the contact surfaces. This reduces the magnitude of axial forces generated during operation at large joint angles, thereby reducing shudder disturbances while maintaining adaptability.
Data Source
AI summary
A constant velocity joint for a drive system of a vehicle comprises: a spider trunnion for transmitting torque between first and second shaft of the drive system, the spider trunnion including a spherical outer surface; and a roller assembly operatively attached on the spider trunnion, the roller assembly including an inner roller, an outer roller, and a plurality of needle rollers engaged between the inner and outer rollers, wherein the inner roller includes a tapered outer surface with a taper angle (θt), and the outer roller includes a tapered inner surface with the same taper angle (θt). The taper angle (θt) is preferably in a range from about 0.23° and to about 1.17°, and selected in consideration of both accommodating the inner roller to move without jamming in an entire effective movement range under presence of a maximum joint angle of the drive system, and preventing self separation of the roller assembly by jamming stop between the inner, outer and needle rollers due to the tapered structure of the rollers. The inner roller is preferably configured to have a ratio LL/RR1 in a range from about 0.11 to about 0.20, where LL is a distance from the center of the spider trunnion to a starting edge of the chamfer or recessed area of the inner roller at initial or neutral position thereof, and RR1 is a radius of the spherical surface of the spider trunnion.