Electric Power Steering Adjusting Sleeve Preload Control
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Solution Overview
Problem
Adjusting the preloading force in electric power steering systems is complex and expensive due to the numerous influencing parameters and components involved, making it difficult to achieve a consistent tolerance range.
Innovation Solution
A method involving an adjusting sleeve with a press fit into the worm shaft's axial opening, where a spring element applies a preloading force, allowing for individual adjustment of the sleeve's position to optimize the preloading force, simplifying the adjustment process by transferring it to a single easily adjustable element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple components (coupling device and preloading device) are used to apply preloading force to the worm shaft, then the preloading force can be distributed across multiple elements, but the adjustment of preloading force becomes complex and expensive due to the large number of influencing parameters and components
Solution Approach 1:
The invention extracts the adjustment function from the complex multi-component system (coupling device and preloading device) and concentrates it into a single adjusting sleeve. This sleeve is press-fitted into the worm shaft and can be individually adjusted in axial position to set the preloading force, thereby simplifying the adjustment process while maintaining reliability through the frictional connection that prevents unintentional displacement
Solution Approach 2:
The invention changes the adjustable parameter from multiple component parameters (coupling device axial force, preloading device force, various tolerances) to a single parameter: the axial position of the adjusting sleeve. By measuring individual components and calculating the optimal sleeve position, the system achieves precise preloading force control through one parameter instead of multiple interacting parameters
2Manufacturing precision
If individual adjustment of preloading force is implemented for each electric power steering system, then the preloading force can be optimized within tolerance range, but the adjustment process becomes more time-consuming and costly without the simplifying措施
Solution Approach 1:
The invention performs preliminary measurement of individual components (worm shaft, drive shaft, housing, spring element) before assembly to determine their actual dimensions and deviations from standard dimensions. Based on these measurements, the optimal axial position of the adjusting sleeve is calculated in advance, so that when the system is assembled, the preloading force is already optimized within the tolerance range without requiring complex real-time adjustment procedures
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 straightforward and individual adjustment of the preloading force for each electric power steering system, ensuring it falls within a predefined tolerance range, reducing the complexity and cost associated with component alignment.
Implementation Method 1
a spring element is installed in the adjusting sleeve, so that the spring element on one end is supported axially on the drive shaft and on its other end it is supported axially on the adjusting sleeve, and the spring element acts upon the worm shaft with the preloading force in the axial direction via the adjusting sleeve
Implementation Method 2
There is a frictional connection between the adjusting sleeve and the worm shaft, wherein the force necessary to move the adjusting sleeve within the axial opening, must be greater than the force exerted by the spring element on the adjusting sleeve
Data Source
AI summary
A method to manufacture electric power steering systems is proposed. First, an electric motor having a drive shaft, a coupling device, and a worm gear having a worm shaft are provided. Then, an adjusting sleeve is provided, and an individual axial position of each adjusting sleeve in its associated opening is determined in order to achieve a specific axial preloading force on the worm shaft. The adjusting sleeve is press-fitted into the axial opening in the determined axial position, and a spring element is installed in the adjusting sleeve so that the spring element is supported on one end axially on the drive shaft and on its other end it is supported axially on the adjusting sleeve, and said spring element acts upon the worm shaft with the preloading force in the axial direction via the adjusting sleeve.