Universal Joint Yoke Structure for Lower Steering Friction
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Solution Overview
Problem
The existing universal joints in power steering systems experience increased friction due to bending torque, which is not effectively managed, leading to higher steering friction and discomfort in vehicle operation.
Innovation Solution
A universal joint design featuring a rigidity-weakening portion with a reduced cross-sectional area and a concave outer surface is introduced, concentrating stress in this area to minimize deformation and reduce bending torque, thereby decreasing friction. Additionally, an intermediate yoke and shaft portion are integrally formed rather than welded, to prevent frictional force increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a bolt is fastened to the hollow-shaped tab to couple the yoke and shaft together, then the connection strength is improved, but the yoke deforms as a whole causing increased bending torque and friction
Solution Approach 1:
The patent introduces a rigidity-weakening portion with reduced cross-sectional area in the yoke, creating a localized region with different mechanical properties. This allows the yoke to have varying rigidity: stronger in some areas and more flexible in others, enabling stress concentration in the rigidity-weakening portion while maintaining overall structural integrity and reducing harmful bending torque
Solution Approach 2:
The patent changes the geometric parameters of the yoke by introducing a rigidity-weakening portion with reduced cross-sectional area and a concave shape. This parameter change modifies the stress distribution characteristics, allowing stress to concentrate in the rigidity-weakening portion during bolt fastening, thereby reducing deformation in the bearing area and bending torque
2Reliability
If the yoke deforms when the bolt is fastened, then the connection is secured, but the hollow portion deforms causing increased bearing pressure and friction
Solution Approach 1:
The rigidity-weakening portion creates a localized flexible zone that absorbs deformation energy, preventing stress transmission to the hollow portion where the bearing is pressed. This localized quality change ensures that connection reliability is maintained while the bearing area remains undeformed and free from excessive pressure
Solution Approach 2:
The rigidity-weakening portion acts as an intermediary element between the bolt fastening point and the hollow portion. It mediates the stress and deformation, allowing the bolt to secure the connection while preventing harmful stress transmission to the bearing area, thus reducing bearing pressure and friction
Data Source
AI summary
A universal joint configured to reduce the steering friction by decreasing the bending torque of a yoke. The universal joint includes a body portion formed at one end of a yoke for a shaft to be coupled thereto, a wing portion formed at the other end of the yoke for a bearing to be pressed thereinto, and a rigidity-weakening portion formed in a shape of a reduced cross-sectional area in a portion extending from the body portion to the wing portion.