Electric Power Steering Stator Segmentation for Moisture Short Circuit Prevention
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Solution Overview
Problem
In electric power steering devices, rainwater entering the housing due to damaged rubber boots can cause electrical short circuits, leading to failure of the steering assist function, especially when the electric motor is positioned lower than the rack shaft, potentially making steering difficult.
Innovation Solution
The stator windings are vertically divided into upper and lower areas, with one system wound on the top and the other on the bottom, allowing independent control of each system to minimize the risk of short circuits, ensuring continued steering assist even if rainwater enters the housing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the electric motor is disposed at a position lower than the rack shaft to facilitate rainwater drainage, then drainage performance is improved, but the risk of electrical short circuit increases when rainwater enters the housing
Solution Approach 1:
The stator windings are segmented into two independent systems (first and second systems) with separate winding sets. This segmentation ensures that if one system experiences a short circuit due to rainwater exposure, the other system remains functional, maintaining steering assist capability while accommodating the motor's lower position for drainage.
Solution Approach 2:
Different winding systems are positioned at different locations within the stator structure. The first system windings and second system windings are spatially separated, creating local quality differences that protect against uniform water exposure. This allows the motor to be positioned lower for drainage while minimizing short circuit risk through localized winding protection.
2Reliability
If the winding is divided into two systems to provide backup steering assist, then reliability is improved, but the complexity of the winding configuration increases
Solution Approach 1:
The winding is divided into two independent systems with separate winding sets, allowing one system to backup the other in case of failure. This segmentation provides reliability through redundancy while maintaining a systematic approach to the increased complexity.
Solution Approach 2:
The first and second winding systems are configured with asymmetric characteristics, including different winding arrangements and control pathways. This asymmetry ensures independence between systems, providing backup capability while managing complexity through deliberate structural differentiation rather than symmetric duplication.
3Reliability
If the stator windings are vertically divided into upper and lower areas with independent control, then the risk of electrical short circuit is reduced, but the control system complexity increases
Solution Approach 1:
The stator windings are vertically segmented into upper and lower areas with independent control systems. This segmentation reduces short circuit risk by isolating potential failure zones while maintaining manageable control complexity through modular independent control of each vertical section.
Solution Approach 2:
The winding systems are arranged in the vertical dimension (upper and lower areas) rather than only horizontal positioning. This dimensional arrangement provides natural separation against water exposure paths while keeping control complexity manageable through vertical zonation of independent control systems.
Data Source
AI summary
There is provided a novel electric power steering device capable of continuing a steering assist function as much as possible even in an environment where moisture enters inside a housing of an electric motor due to breakage of a rubber boot and an electrical short circuit phenomenon occurs.A stator 14 around which a winding is wound is vertically divided into two areas in the direction of gravity, a winding 16 of one system is wound in the upper stator area of the stator 14 while the winding 16 of the other system is wound in the lower stator area of the stator 14, and power of the winding of one system is controlled by an electronic control means 33 of one system while power of the winding of the other system is controlled by an electronic control means 34 of the other system. Even if moisture enters inside the housing of the electric motor due to breakage of the rubber boot, occurrence of the electrical short circuit phenomenon is suppressed at least in the winding wound on the upper side, whereby the steering assist can be continued.