Steering Shaft Support Structure for Power Steering
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Solution Overview
Problem
The conventional steering shaft supporting structure in vehicles is susceptible to inaccuracies and changes in the vehicle body frame, affecting the stability and performance of the electrically-operated power steering system due to variations in the positional relationship between different supporting members.
Innovation Solution
The electrically-operated power steering unit is supported by the lower section of the vehicle body frame using a gear case and housing with a bearing, where both the input and output shafts are linked to the same frame, and a handlebar stopper limits the steering shaft's rotation to prevent torsion bar overload, utilizing a double-row bearing for enhanced load capacity and axial displacement to mitigate external forces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the steering shaft is supported by different members (upper pipe and front cross pipe) of the vehicle body frame, then the structural complexity is reduced and ease of manufacture is improved, but the reliability deteriorates due to variations in positional relationship caused by manufacturing inaccuracies and frame shape changes
Solution Approach 1:
The patent merges the support function for both the upper shaft and lower shaft into a single integrated support structure (the gear case housing). By attaching both shafts to the same housing that is mounted on the front cross pipe, the system eliminates the need for separate support members, thereby maintaining ease of manufacture while significantly improving reliability by eliminating positional relationship variations between different frame members
2Device complexity
If the upper shaft and lower shaft are supported by different members of the vehicle body frame, then the device complexity is reduced, but the stability deteriorates due to variation in distance and positional relationship between supporting members
Solution Approach 1:
The patent combines multiple support functions into a single integrated housing structure that supports both the upper shaft and lower shaft. This merging approach maintains simple device complexity while dramatically improving stability by ensuring that both shafts are supported by the same reference frame member, eliminating distance and positional relationship variations that would otherwise compromise stability
3Adaptability or versatility
If the steering shaft supporting structure uses separate members for upper and lower shaft support, then the adaptability is improved for different frame configurations, but the precision of positional relationship deteriorates due to manufacturing inaccuracies and frame shape changes
Solution Approach 1:
The patent integrates the support structure for both shafts into a single housing unit that is mounted on one frame member. This approach maintains adaptability to different frame configurations while significantly improving manufacturing precision by providing a common reference plane for both shaft supports, thereby eliminating cumulative positioning errors from multiple separate mounting locations
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 the system's susceptibility to manufacturing inaccuracies and frame changes, ensuring stable operation by distributing loads effectively and preventing torsion bar overload, while also protecting against external forces and environmental elements like dust and water.
Implementation Method 1
a lower end portion of a steering shaft being rotatably supported by a housing annexed to the gear case with a bearing interposed in between
Data Source
AI summary
To make an electrically-operated power steering unit less susceptible to influence of change in a positional relationship between supporting sections respectively at the two ends of the electrically-operated power steering unit. A gear case included in a electrically-operated power steering unit is attached to the lower section of a vehicle body frame, and the lower end portion of a steering shaft is rotatably supported by a housing annexed to the gear case with an upper bearing interposed in between, in a vehicle in which an input shaft provided to the electrically-operated power steering unit is linked to the lower end portion of the steering shaft, and in which an output shaft provided to the electrically-operated power steering unit is rotatably supported by the lower section of a vehicle body.