Tripod Constant Velocity Joint Trunnion Spherical Geometry
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Solution Overview
Problem
Conventional tripod type constant velocity joints experience significant friction and shudder due to axial forces, leading to transverse vibrations, and face challenges in lubrication and manufacturing complexity, resulting in inconsistent quality and high costs.
Innovation Solution
The design incorporates trunnions with opposing spherical contact surfaces and planar or angled surfaces perpendicular to the load, featuring circular or oval grooves for enhanced lubrication and reduced friction, along with a cross-sectional shape that varies in thickness to improve mechanical strength and ease of assembly, while maintaining a compact size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If conventional tripod type constant velocity joints are used, then torque transmission is achieved, but significant friction and shudder occur due to axial forces
Solution Approach 1:
The patent applies spheroidality by providing spherical contact surfaces on the trunnions that engage with corresponding spherical contact surfaces on the inner rollers. This spherical geometry allows for smooth rolling contact and accommodates angular movements while maintaining constant velocity, thereby reducing friction and eliminating shudder during torque transmission.
Solution Approach 2:
The patent changes the contact geometry parameters from conventional designs to spherical surfaces with specific curvature radii. The spherical contact surfaces have optimized radius ratios that enable pure rolling motion and reduce sliding friction, thus eliminating the harmful axial forces and shudder while maintaining effective torque transmission.
2Reliability
If conventional tripod joints are used, then constant velocity movement is achieved, but lubrication challenges and manufacturing complexity increase
Solution Approach 1:
The patent applies local quality by providing grooves at specific locations on the spherical contact surfaces of the trunnions. These grooves are strategically positioned to retain lubricant at the contact zones, ensuring proper lubrication where it is most needed. This localized feature simplifies the overall manufacturing process compared to complex conventional designs while maintaining reliable constant velocity movement.
Solution Approach 2:
The spherical contact surfaces with optimized curvature radii simplify the manufacturing process by allowing the use of spherical grinding and polishing techniques. The grooves cut into these spherical surfaces are easier to manufacture than complex conventional geometries, reducing manufacturing complexity while ensuring reliable constant velocity movement through proper lubrication.
3Object-generated harmful factors
If trunnions with spherical contact surfaces are used, then friction is reduced, but manufacturing precision requirements increase
Solution Approach 1:
The patent specifies optimized radius ratios for the spherical contact surfaces (where the radius of the trunnion spherical surface is 0.5 to 2.0 times the radius of the inner roller spherical surface). This parameter optimization reduces the sensitivity to manufacturing tolerances, allowing friction to be minimized while maintaining achievable manufacturing precision levels.
Solution Approach 2:
The grooves provided on the spherical contact surfaces serve as lubricant reservoirs, compensating for minor variations in spherical surface precision. This localized feature ensures that even with moderate manufacturing precision, the spherical contact surfaces can achieve low friction through proper lubrication retention.
4Adaptability or versatility
If the joint operates with wide range of angles, then versatility is improved, but axial forces and shudder increase
Solution Approach 1:
The spherical contact surfaces on both the trunnions and inner rollers enable the joint to operate smoothly over a wide range of angles. The spherical geometry maintains constant velocity and eliminates shudder even at large joint angles by ensuring pure rolling contact and accommodating angular movements without generating harmful axial forces.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration reduces frictional resistance, enhances mechanical strength, ensures reliable operation under adverse conditions, and simplifies assembly, thereby improving the durability and performance of the constant velocity joint.
Implementation Method 1
each trunnion includes two opposing spherical contact surfaces disposed in the directions subject to the load
Implementation Method 2
This configuration reduces frictional resistance
Implementation Method 3
a groove of circular or oval shape is formed on the spherical contact surface of each trunnion, the groove for retaining grease therein to lubricate the contact surface
Data Source
AI summary
A constant velocity joint comprises: a hollow housing having a plurality of axially-extending guide grooves; a tripod having a plurality of trunnions positioned in the guide grooves of the hollow housing; and a roller assembly including an inner roller having a spherical inner face and an outer roller mounted on an outer face of each inner roller, the roller assembly for transmitting a load between the first and second rotating shafts. A cross sectional shape of the trunnion, taken in a direction perpendicular to the longitudinal axis of the trunnion, has a thickness at one or both lateral sides of the trunnion the same as or slightly less than a maximum non-interfering thickness of the trunnion, the maximum non-interfering thickness measured with the inner roller inclined by a predetermined degree relative to the longitudinal axis of the trunnion to assemble the trunnion into the inner roller.