Steering Shaft Yoke Coupling Rattling Detection
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Solution Overview
Problem
Current shaft-and-yoke coupling structures in vehicle steering systems fail to provide a fail-safe function and alert the driver to abnormalities, such as broken welded portions, leading to prolonged unsafe driving.
Innovation Solution
A shaft-and-yoke coupling structure with a stepped portion and an insertion convex portion on the steering transmission shaft, and a corresponding annular receiving portion and insertion recess on the yoke, allowing engagement with a predetermined play in the direction of rotation upon welded portion breakage, providing a rattling feeling for steerability and abnormality recognition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the yokes and shafts are fixed integrally by welding, then the torque transmission is strong and reliable, but the driver cannot recognize the occurrence of abnormality when welded portions break
Solution Approach 1:
The connection between the yoke and shaft is segmented into two functional parts: a welded portion for torque transmission and an insertion convex portion with insertion recess portion for abnormality detection. When the welded portion breaks, the insertion portions remain engaged but allow relative movement, providing a rattling sensation to the driver while the shaft and yoke remain physically connected.
Solution Approach 2:
The insertion convex portion and insertion recess portion act as an intermediary mechanism between the welded connection and the driver's perception. This intermediary structure provides a mechanical feedback (rattling sensation) that mediates the information about welded portion breakage to the driver, enabling abnormality recognition while maintaining torque transmission capability.
2Reliability
If serrated fitting and/or swaging are added to maintain torque transmission after welding breakage, then fail-safe function is achieved, but the driver still cannot recognize the abnormality
Solution Approach 1:
The connection structure is segmented into a welded portion for primary torque transmission and an insertion portion system for fail-safe functionality. The insertion convex portion protruding from the stepped portion engages with the insertion recess portion, creating a mechanical backup that maintains torque transmission while providing detectable rattling motion when welding fails.
Solution Approach 2:
The insertion convex portion and insertion recess portion create a feedback mechanism through rattling sensation. When the welded portion breaks, the relative movement between the engaged insertion portions produces a rattling feeling that feeds back to the driver, providing information about the abnormality while maintaining the fail-safe torque transmission path.
3Loss of information
If the insertion convex portion and insertion recess portion are engaged with play in the direction of rotation, then the driver can recognize abnormality through rattling feeling, but the structure becomes more complex
Solution Approach 1:
The insertion convex portion and insertion recess portion are merged with the existing welded connection structure. The insertion convex portion is integrated into the shaft's stepped portion, and the insertion recess portion is formed in the yoke, combining multiple functions (torque transmission, abnormality detection, and fail-safe operation) into a unified coupling structure without adding separate components.
Solution Approach 2:
The insertion convex portion and insertion recess portion serve multiple functions: they provide abnormality detection through rattling sensation, maintain torque transmission when welding breaks, and enable fail-safe operation. This multi-functionality reduces the need for separate detection and backup systems, simplifying the overall device complexity.
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
Enables the driver to steer the vehicle with a rattling sensation, indicating an abnormality, ensuring safe operation until repair, while maintaining torque transmission and steerability.
Implementation Method 1
the annular receiving portion facing and fixed to the stepped portion via a welded portion
Data Source
Figure 1
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Figure 3
AI summary
Provided is a shaft-and-yoke coupling structure (P) for coupling a steering transmission shaft (5) and a yoke (41) of a universal joint (4). An end portion (5a) of the steering transmission shaft (5) joined to the yoke (41) has a stepped portion (51) and an insertion convex portion (52) protruding from the stepped portion (51) in the axial direction (X1) of the steering transmission shaft (5). The yoke (41) has an annular receiving portion (53) facing and fixed to the stepped portion (51) via a welded portion (55) and an insertion recess portion (54) surrounded by the receiving portion (53) in which the insertion convex portion (52) is inserted. The insertion convex portion (52) and the insertion recess portion (54) are arranged to be engaged with each other with a predetermined amount of play (Q1) in the direction of rotation when the welded portion (55) is broken.