Push Rod Guide Roller Preload for Play-Free Steering Assembly
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Solution Overview
Problem
Existing steering systems face challenges in ensuring play-free guidance of push rods while maintaining acceptable frictional forces, with complex resistance adjustment and high production costs due to the need for precise mechanical coupling and material hardening.
Innovation Solution
A steering system design using a roller axis that can be moved and fixed to create a preload against a push rod, employing a rolling bearing and counterbearing to adjust and maintain defined resistance, allowing for cost-effective assembly and precise adjustment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conically shaped rollers are fastened in rings that surround the push rod with Allen screws to clamp the clamping rings, then the resistance against displacement can be adjusted, but the device complexity increases and the ease of operation deteriorates due to complex assembly and adjustment procedures
Solution Approach 1:
The invention extracts the adjustment function from the complex multi-component clamping ring system and concentrates it into a single roller axis that can be directly positioned along the push rod. This simplifies the device by removing unnecessary intermediate components like Allen screws and multiple clamping rings, while maintaining the ability to adjust resistance against push rod displacement.
Solution Approach 2:
The invention changes the adjustment parameter from angular positioning of multiple clamping rings to linear positioning of a single roller axis along the push rod. By moving the roller axis to different positions, the preload and thus the resistance can be simply adjusted without complex mechanical operations, improving ease of operation while reducing device complexity.
2Ease of operation
If small-area contact rolling elements are used between the pressure piece and the push rod to reduce frictional forces, then the frictional forces are reduced, but the manufacturing precision requirements increase due to the need for hardened materials
Solution Approach 1:
The invention transitions from point contact (small-area rolling elements) to line contact (cylindrical roller axis along the push rod). This dimensional change from 0D/2D contact to 1D line contact increases the contact area, distributing the load and reducing the need for extreme material hardness while maintaining low frictional resistance through rolling contact.
Solution Approach 2:
The invention uses a cylindrical roller axis that can be made from composite or surface-treated materials combining hardness for wear resistance with toughness for impact resistance. This allows the roller axis to withstand high contact pressures without requiring the entire push rod to be hardened, reducing manufacturing complexity while maintaining low friction.
3Measurement precision
If the roller axis is made movable and fixable to generate preload against the push rod, then the resistance adjustment precision is improved, but the device complexity increases due to additional mounting mechanisms
Solution Approach 1:
The invention implements preliminary positioning of the roller axis during assembly, where the roller axis can be temporarily fixed at a predetermined position to establish the initial preload. This preliminary action allows for precise resistance adjustment without requiring complex real-time adjustment mechanisms during operation, as the position is set in advance and maintained.
Solution Approach 2:
The roller axis mounting mechanism is designed to be self-adjusting through the interaction between the roller axis position and the push rod geometry. The system automatically establishes the correct preload through the mechanical interaction of components without requiring external adjustment devices, reducing overall device complexity while maintaining adjustment precision.
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 simple, reliable, and cost-effective assembly with precise resistance adjustment, reducing frictional forces and material requirements, suitable for steer-by-wire systems.
Implementation Method 1
the roller axis (20) can be moved towards the push rod (12) to generate a preload
Implementation Method 2
the rollers can be clamped against the push rod (12) in a kind of torsional movement... the frictional forces generated by the guide mechanism
Data Source
Figure 1
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AI summary
The invention relates to a steering system (10) for a motor vehicle, comprising a pushrod (12), wherein the steering system (10) has a guide device (14) for guiding the movement of the pushrod (12) in its longitudinal direction, the guide device (14) being designed to prevent rotation of the pushrod (12) about its longitudinal axis. The pushrod (12) has a flattened section (16) wherein a roller (18) bears against the flattened section (16) under a preload, the roller (18) being rotatably mounted on a roller axle (20). To adjust the resistance against displacement of the pushrod (12) in the guide device (14), the roller axle (20) can be moved towards the pushrod (12) to generate the preload and fixed in its position.