Reduction Gear Spring Element for Uniform Bearing Preload
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Solution Overview
Problem
Electromechanical steering systems face issues with noise generation due to friction and uneven load distribution, which can lead to bearing damage and limited spring travel, especially in reduction gear applications.
Innovation Solution
A spring element with annular and U-shaped spring arms is used between the worm gear and the inner ring of the bearing, providing a uniform preload and reducing noise by distributing force along the longitudinal axis, while protecting the bearing from damage and allowing for increased spring travel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional preloading elements are used, then the bearing is preloaded, but noise is generated due to friction and load distribution is uneven
Solution Approach 1:
The spring element is divided into multiple spring arms (at least two) that are arranged symmetrically around the longitudinal axis. Each spring arm independently contacts the bearing inner ring and worm gear, distributing the preload force evenly across multiple contact points. This segmentation eliminates the uneven load distribution and friction-induced noise associated with conventional single-element preloading mechanisms.
2Length of moving object
If corrugated springs are used, then spring travel is increased, but a flat distribution of load is not possible and tilting moments arise
Solution Approach 1:
Each spring arm is designed with an asymmetric geometry featuring a first leg extending radially outward from the longitudinal axis and a second leg extending parallel to the longitudinal axis. This asymmetric configuration allows the spring arms to accommodate large travel distances while maintaining symmetric arrangement around the axis, thereby distributing load evenly and preventing tilting moments that would arise from asymmetric spring designs.
3Length of moving object
If large spring travel is implemented, then the spring can accommodate more movement, but the distance in radial direction is limited
Solution Approach 1:
The spring arms utilize the longitudinal dimension (parallel to the rotational axis) to achieve large travel distances, rather than relying solely on radial expansion. The second leg of each spring arm extends parallel to the longitudinal axis, allowing the spring to accommodate significant axial movement while maintaining a compact radial footprint. This dimensional transition enables large spring travel within the limited radial space of the gearbox.
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 effectively reduces noise and enhances load distribution, preventing bearing damage and enabling larger spring travel, thus improving the operational efficiency and reliability of electromechanical steering systems.
Implementation Method 1
a spring element which in the installed state is disposed between the inner ring of the second bearing and the worm gear. The spring element has an at least partially annular main body which in the installed state extends coaxially with the longitudinal axis, spring arms which in the circumferential direction are spaced apart from the longitudinal axis emanating from the external circumferential side of the main body
Data Source
AI summary
An electromechanical steering system may include a reduction gearbox where a worm gear is mounted in first and second bearings rotatably about a longitudinal axis. Rolling elements are disposed between inner and outer rings of the bearings. The inner rings are rotationally fixed on a shaft driven by the worm gear. A spring element is disposed between the inner ring of the second bearing and the worm gear. The spring element has an at least partially annular main body that when installed extends coaxially with the longitudinal axis. Spring arms in a circumferential direction are spaced apart from the longitudinal axis emanating from an external circumferential side of the main body. A first spring arm has a first leg that points away from the longitudinal axis and a second leg on which a free end is disposed, with the second leg running at least partially parallel to the longitudinal axis.