Universal Joint Yoke Elastic Base for Bolt Damage Prevention
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Solution Overview
Problem
Existing cross-type universal joints in automobile steering systems face issues with bolt damage and reduced rigidity due to excessive tightening, and current manufacturing methods are costly and complex, especially when dealing with large loads from electric-powered power steering apparatuses.
Innovation Solution
The proposed yoke design features a partial cylindrical base section with angled through and screw holes, and work-hardened joint arm sections, along with a manufacturing method that reduces the inner diameter of the base section to allow concentric hole formation and serration alignment, preventing bolt bending and enhancing rigidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the base section inner diameter is reduced to allow concentric hole formation, then manufacturing precision and bolt alignment are improved, but the ease of shaft insertion deteriorates
Solution Approach 1:
The base section inner diameter is reduced in advance during manufacturing to enable precise concentric formation of through holes and screw holes. This preliminary dimensioning ensures accurate hole alignment while the elastic recovery after processing maintains sufficient insertion clearance for the rotating shaft.
Solution Approach 2:
The base section inner diameter parameter is dynamically adjusted: reduced during the hole formation process to ensure concentricity, then allowed to recover elastically to provide adequate insertion clearance. This parameter transformation resolves the contradiction between precision and ease of operation.
2Reliability
If the yoke is tightened to secure the rotating shaft, then the strength and reliability are improved, but the bolt may bend or break due to excessive tightening
Solution Approach 1:
The seating surface section is specifically positioned on the first flange section to locally bear the tightening load. This localized load bearing prevents excessive force from being transmitted to the bolt, thereby protecting bolt integrity while ensuring reliable joint security through targeted load distribution.
Solution Approach 2:
The seating surface section acts as an intermediary element between the flange sections and the bolt. It mediates the tightening force by providing a bearing surface that distributes the load, preventing direct transmission of excessive tightening forces to the bolt and avoiding bolt bending or breakage.
3Strength
If the joint arm sections are designed to support large loads from electric-powered power steering, then the strength is improved, but the manufacturing complexity and cost increase
Solution Approach 1:
The joint arm sections undergo work hardening through plastic deformation to fundamentally change their material properties, significantly increasing strength and load-bearing capacity. This material transformation achieves high strength requirements through a relatively simple manufacturing process rather than complex structural design.
Solution Approach 2:
The manufacturing process temporarily discards the original material structure of the joint arm sections through plastic deformation and work hardening, transforming the material to achieve enhanced strength. This recovery of material properties through controlled deformation provides a cost-effective alternative to complex manufacturing methods.
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 design effectively prevents bolt bending and breakage while maintaining high rigidity, allowing for smooth operation and increased durability under large loads, with a simplified and cost-effective manufacturing process.
Implementation Method 1
the joint arm sections, and a manufacturing method therefor, are work-hardened
Data Source
Figure 1(A)~1(B)
Figure 2(A)~2(B)
Figure 3(A)~3(B)
AI summary
A yoke is provided in which damage such as bending of a bolt for joining and fastening the base section 14d of the yoke 12s to the end section of a rotating shaft does not easily occur even when that bolt is excessively tightened. In the present invention, a force is applied to both a first flange section 16d and a second flange section 17d in a direction toward each other, and with the inner diameter of the base section 14d elastically reduced, a through hole 25, screw hole 26 and seating surface section 19d are formed. After that, the force is released and the inner diameter of the base section 14d expands by its own elastic force. Alternatively, with the inner diameter of the base section 14d reduced, the through hole 25, screw hole 26 and seating surface section 19d are formed, after which the first flange section 16d and second flange section 17d are plastically deformed in the direction away from each other to expand the inner diameter of the base section 14d.