Ball Screw Steering Nut Pivot Bearing With Automatic Play Elimination
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Solution Overview
Problem
Existing steering systems with recirculating ball threads and transmission nuts are complex and costly due to the need for a loading apparatus to compensate for plastic deformation and ensure low friction and play-free operation, which complicates the structure and increases production costs.
Innovation Solution
A steering system with a ball screw drive and a transmission nut that uses a flexible drive mechanism, such as a toothed belt, where the transmission nut is decoupled from the pivoting bearing, and features a sliding coating or lubricant between joint sections to minimize friction, eliminating the need for a complex loading apparatus and allowing for automatic play elimination, thus simplifying the structure and reducing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a loading apparatus is used to compensate for plastic deformation and ensure play-free operation, then reliability and low friction are improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent removes the loading apparatus from the steering system. Instead of using a complex loading apparatus to compensate for plastic deformation and ensure play-free operation, the invention relies on the self-compensating properties of the plastic bearing layer that automatically adapts to deformation over time, thereby eliminating the need for additional adjustment mechanisms while maintaining reliability.
Solution Approach 2:
The plastic bearing layer is designed to self-compensate for plastic deformation through its material properties. As the steering system operates, the plastic layer gradually deforms and settles, automatically maintaining optimal contact and play-free operation between the transmission nut and mechanism wheel without requiring external adjustment devices.
2Ease of operation
If a separate plastic plain bearing layer is used to minimize friction, then ease of operation is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent integrates the bearing function directly into the joint sections of the mechanism wheel and transmission nut by applying a plastic bearing layer to these surfaces. This merging of the bearing function into the existing structural components eliminates the need for separate bearing elements while maintaining low friction and improving ease of operation.
Solution Approach 2:
The plastic bearing layer is applied as a relatively simple, cost-effective coating on the joint sections rather than using complex precision-bearing components. This approach uses inexpensive plastic material that can be applied through straightforward manufacturing processes, reducing both device complexity and manufacturing cost while achieving the desired low-friction operation.
3Reliability
If joint sections are pressed elastically by a prestressed loading apparatus, then reliability is improved through play-free state, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent eliminates the prestressed loading apparatus entirely. The play-free state is achieved not through active elastic pressing by complex loading devices, but through the natural settling and deformation characteristics of the plastic bearing layer that automatically maintains optimal contact between mating surfaces during normal operation.
Solution Approach 2:
The system uses the operational loads and natural deformation of the plastic bearing layer to self-establish and maintain the play-free state. During normal steering operation, the plastic layer gradually deforms under load to eliminate gaps and ensure continuous contact, eliminating the need for separate prestressing mechanisms.
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
The solution achieves low friction and play-free operation without the need for a loading apparatus, resulting in a simpler, more robust, and cost-effective steering system with reduced adjustment travel requirements and minimal settling behavior over the service life.
Implementation Method 1
features a sliding coating or lubricant between joint sections to minimize friction
Implementation Method 2
a ball screw drive, to which end the steering rod configures a recirculating ball thread in at least one section which interacts with a transmission nut
Data Source
AI summary
A steering system has a steering rod longitudinally displaceable in a housing and a steering motor acting on the steering rod via a ball screw drive. The steering rod has a recirculating ball thread interacting via spherical transmission elements with a transmission nut driven by the steering motor and that is rotatably mounted by a bearing arrangement with a pivot bearing having an inner ring to which a mechanism wheel is fixedly attached. The transmission nut is pivotably mounted on the mechanism wheel about a pivot axis oriented perpendicularly to the longitudinal axis of the steering rod, and has a curved joint section which interacts with a curved joint section of the mechanism wheel to form a pivoting bearing. In order to realize low-friction movement capability of the pivoting bearing, at least one of the joint sections has a sliding coating, and/or a lubricant is arranged between the joint sections.