Steering Pinion Preload for Tight Worm Wheel Meshing
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Solution Overview
Problem
Existing vehicle steering systems face challenges in efficiently transferring torque from the steering wheel to the steerable wheels, particularly in maintaining tight meshing between the pinion and worm wheel under varying steering torques and wear conditions.
Innovation Solution
The steering system incorporates a pinion supported by first and second bearings, with a worm wheel meshed with the pinion to transfer torque. A pressing device applies a pressing force to the pinion via the second bearing, urging it toward the worm wheel to maintain tight meshing, and an elastic element is used to reduce noise and vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the pinion is supported by two ball bearings aligned along the rotational axis, then the pinion can rotate smoothly, but the meshing between the pinion and worm wheel becomes loose under varying steering torques and wear conditions
Solution Approach 1:
The patent replaces the fixed alignment of ball bearings with a dynamic pressing mechanism that allows the pinion position to adjust automatically. The pressing device applies axial force to the pinion, enabling it to move dynamically toward the worm wheel to maintain tight meshing under varying torque and wear conditions, while still allowing smooth rotation through the bearing support.
Solution Approach 2:
The patent changes the operational parameters of the bearing support system by introducing axial pressing force. Instead of relying solely on the fixed geometric alignment of ball bearings, the system actively modifies the axial position of the pinion through controlled pressing force, thereby maintaining optimal meshing parameters under varying operating conditions.
2Reliability
If a pressing device applies pressing force to the pinion via the second bearing, then tight meshing between pinion and worm wheel is maintained, but the complexity of the bearing support system increases
Solution Approach 1:
The patent makes the second bearing serve dual functions: it continues to provide rotational support for the pinion while also serving as the application point for axial pressing force. This multi-functionality allows the pressing device to act through the existing bearing structure rather than requiring a separate mounting mechanism, thereby reducing overall system complexity.
Solution Approach 2:
The patent combines the pressing function with the existing bearing support structure. The pressing device integrates with the second bearing assembly, merging the support and pressing functions into a unified structural arrangement that avoids adding separate complex mounting mechanisms.
3Object-affected harmful factors
If an elastic element is added to reduce noise and vibration, then NVH performance improves, but the device complexity increases
Solution Approach 1:
The patent introduces an elastic element as an intermediary component between the pressing device and the pinion or housing. This elastic intermediary absorbs vibrations and dampens noise by deformable compliance, reducing NVH while maintaining the necessary pressing force through its elastic properties rather than requiring complex active control systems.
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 effectively transfers torque from the steering wheel to the steerable wheels, maintains tight meshing between the pinion and worm wheel, and reduces noise, vibration, and harshness (NVH) by adjusting the bearing preload and using an elastic element.
Implementation Method 1
an elastic element is used to reduce noise and vibration
Data Source
AI summary
A steering system for use in turning steerable vehicle wheels includes a steering wheel and a housing. A pinion is in the housing and connected to the steering wheel such that rotation of the steering wheel results in rotation of the pinion about a rotational axis relative to the housing. A first bearing rotatably supports a first end of the pinon in the housing. A second bearing rotatably supports a second end of the pinon in the housing. A worm wheel is meshed with the pinion in the housing and connected to steerable vehicle wheels. The worm wheel transfers torque from the steering wheel to the steerable vehicle wheels to effect turning of the steerable vehicle wheels. A pressing device applies a pressing force to the second end of the pinion via the second bearing to urge the pinion toward the worm wheel.