Universal Joint Trunnion Locking to Prevent Yoke Ear Spreading
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Solution Overview
Problem
Existing universal joints in vehicle drivetrains are prone to bearing cap spinning and yoke weakening under torsional loads, leading to snap ring loosening and potential failure due to the lack of structures to prevent the spreading of yoke ears.
Innovation Solution
A universal joint design featuring a central body with non-rotatable trunnions and a locking assembly that inhibits the movement of trunnions and yoke ears, ensuring they remain securely locked and prevent spinning and spreading under increasing loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional universal joints with bearing caps and snap rings are used, then the joint can transmit torque between non-collinear shafts, but the bearing caps spin relative to the trunnions and yoke ears under torsional loads, leading to weakening and failure
Solution Approach 1:
The patent applies asymmetry by providing non-circular heads on the trunnions that engage with corresponding non-circular recesses in the yoke ears. This asymmetric geometry prevents relative rotation between the trunnions and yoke ears, eliminating the spinning problem that occurs with conventional circular bearing caps and snap rings under torsional loads.
Solution Approach 2:
The patent implements preliminary action by providing pre-assembled trunnion-yoke ear units where the non-circular heads are already configured to engage with the non-circular recesses. This pre-configured engagement ensures that the anti-spinning mechanism is in place before the universal joint begins operation, preventing wear and failure from the outset.
2Device complexity
If existing universal joints are used without additional locking structures, then the device complexity remains low, but the opposing ears of the yoke spread away from each other under extreme torque, leading to weakening and failure
Solution Approach 1:
The non-circular head and recess geometry inherently prevents spreading of the yoke ears by creating a mechanical interlock that resists separation forces. The asymmetric shape ensures that the trunnions cannot move axially away from the yoke ears under torque loads, providing strength without requiring additional locking structures.
Solution Approach 2:
The patent merges the trunnion and yoke ear into a integrated unit where the non-circular engagement features are built-in. This combination eliminates the need for separate locking mechanisms while providing inherent resistance to ear spreading, thus maintaining low device complexity while improving strength.
Data Source
AI summary
A universal joint for vehicle drivetrains and the like that eliminates the spinning of bearing caps relative to yoke years and trunnions and inhibits inadvertent spreading of opposing ears of a yoke away from each other under increasing torsional loads to reduce wear and failure of the joint. Broadly, the disclosed universal joint includes a central body having a plurality of pairs of opposite apertures, first and second yokes that are disposed about the central body over respective ones of the pairs of apertures, and a plurality of trunnions inserted through the yoke ears and into the apertures of the body to pivotally secure the yokes to the body. Each trunnion is non-rotatable relative to its respective yoke and a locking assembly inhibits movement of each opposite pair of trunnions away from each other thereby inhibiting movement of the opposite ears of each respective yoke away from each other.