Steering Yoke Error-Proofing for Pinch Bolt Assembly Positioning
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Solution Overview
Problem
The assembly of an intermediate shaft and a steering system in automobiles is challenging due to difficulty in accessing the pinch bolt, leading to incorrect assembly and increased inspection time, with instances of the shaft and pinion separating after assembly.
Innovation Solution
A steering assembly with a yoke and an error-proofing device featuring a deflectable portion that blocks and then clears an access path for a fastener, ensuring the pinion shaft is assembled at a predetermined axial position, facilitating correct and robust coupling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pinch bolt is tightened to couple the pinion shaft with the intermediate shaft at a particular location, then the connection is secured, but the assembly may be incorrect and additional inspection time is required
Solution Approach 1:
The error-proofing device performs preliminary verification of correct shaft positioning before the pinch bolt is tightened. The deflectable portion is positioned to block the access path initially, and only when the shaft is correctly positioned does the portion deflect to allow fastener insertion, ensuring correct assembly before final securing.
Solution Approach 2:
The deflectable portion acts as an intermediary between the shaft positioning and the fastener insertion. It mediates the assembly process by conditionally allowing or blocking fastener access based on whether the shaft is correctly positioned, thereby preventing incorrect assembly without requiring additional inspection steps.
2Measurement precision
If additional inspection measurements are performed, then assembly correctness is verified, but assembly time increases
Solution Approach 1:
The error-proofing device performs self-verification of correct assembly positioning. The deflectable portion automatically detects incorrect shaft positioning and blocks fastener access, eliminating the need for separate inspection measurements by the operator. The device itself verifies correctness through its mechanical response.
3Ease of operation
If the pinch bolt access is made easier, then assembly is simplified, but the yoke's clamping characteristics may be compromised
Solution Approach 1:
The error-proofing device is segmented into a fixed portion attached to the yoke and a deflectable portion that moves independently. This segmentation allows the deflectable portion to deflect and clear the access path without compromising the fixed portion's attachment to the yoke, thereby maintaining clamping strength while enabling easier bolt access when correctly assembled.
Solution Approach 2:
The deflectable portion transitions from a static blocking position to a dynamic cleared position when the shaft is correctly inserted. This dynamic behavior allows the device to maintain its error-proofing function while temporarily clearing the access path for the pinch bolt, balancing accessibility requirements with structural integrity.
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
Ensures precise and reliable assembly of the intermediate shaft and pinion shaft, reducing assembly and inspection time, and preventing post-assembly separation, while maintaining the yoke's clamping characteristics without additional efforts or adjustments.
Implementation Method 1
an error-proofing device fixed to the yoke and having a deflectable portion blocking the access path
Implementation Method 2
deflectable upon contact with the pinion shaft to be clear of the access path in a final assembly position
Data Source
AI summary
A steering assembly includes a pinion shaft. The steering assembly also includes a yoke defining a space for axially receiving the pinion shaft and defining an access path for receiving a fastener that couples the pinion shaft to the yoke. The steering assembly further includes an error-proofing device fixed to the yoke and having a deflectable portion blocking the access path in an initial position and deflectable upon contact with the pinion shaft to be clear of the access path in a final assembly position to ensure that the pinion shaft is assembled to the yoke at a predetermined axial position.