Rack-Assist Electric Power Steering Belt Tension Control
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Solution Overview
Problem
Conventional rack-assist-type electric power steering apparatuses experience noise and vibration due to chord vibration in the belt and fluctuating belt tension when the motor pulley is rotated, leading to wear and breakage of components.
Innovation Solution
Incorporation of magnetic bodies on the belt and rack housing to prevent chord vibration by maintaining constant belt tension through magnetic attraction and repulsion forces, reducing noise and ensuring consistent belt tension.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the motor pulley is continuously rotated in forward and reverse directions, then the steering assist function is provided, but chord vibration occurs in the belt causing noise and vibration in the rack housing
Solution Approach 1:
The patent applies magnetic vibration damping elements that generate controlled vibrations to counteract the harmful chord vibrations in the belt. The magnetic elements create oscillating forces that cancel out the vibration frequencies generated during motor pulley rotation, thereby reducing noise and vibration in the rack housing while maintaining steering assist functionality.
Solution Approach 2:
The patent introduces magnetic vibration damping elements as intermediary components between the belt and the rack housing. These elements act as mediators that absorb and dampen the vibration energy transmitted from the belt to the housing, reducing the harmful effects of chord vibration without interfering with the power transmission function.
2Ease of operation
If the motor operates continuously in forward and reverse directions, then steering control is achieved, but belt tension fluctuates causing wear and breakage
Solution Approach 1:
The patent employs magnetic spring elements that dynamically adjust the belt tension parameters based on operating conditions. The magnetic fields generated by these elements provide a restoring force that maintains optimal belt tension during continuous forward and reverse motor operation, preventing excessive tension fluctuations that would otherwise lead to wear and breakage.
Solution Approach 2:
The patent replaces traditional mechanical tensioning mechanisms with magnetic spring elements. These magnetic elements use magnetic field forces instead of mechanical springs or dampers to control belt tension, providing smoother and more consistent tension maintenance during bidirectional motor operation, thereby improving belt reliability.
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 maintains constant belt tension, enhancing the durability and performance of the steering apparatus by preventing chord vibration and wear on components.
Implementation Method 1
Incorporation of magnetic bodies on the belt and rack housing to prevent chord vibration by maintaining constant belt tension through magnetic attraction and repulsion forces
Data Source
AI summary
A rack-assist-type electric power steering apparatus may include: a motor pulley provided on or coupled to a shaft of a motor; a nut pulley provided on or coupled to an outer circumferential surface of a ball nut coupled to a rack bar via a ball; a belt coupled to the motor pulley and the nut pulley, the belt comprising provided with one or more first magnetic bodies; and a rack housing enclosing or housing at least a portion of the motor pulley, the nut pulley and the belt are housed. The rack housing may comprise one or more second magnetic bodies provided on an inner circumferential surface thereof facing or opposite to the belt. Alternatively, the rack housing may comprise a support portion protruding from an inner surface of the rack housing, and one or more second magnetic bodies may be provided on a surface of the support portion.