Motor Cover Sensor Integration for EPS Position Accuracy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing electrically-driven power steering systems face challenges in achieving accurate positional assembly of position detection sensors and are susceptible to switching noise interference from the electric power conversion circuit, leading to inaccurate detection signals.
Innovation Solution
The position detection purpose permanent magnet and magneto resistive effect element are installed on the motor cover opposite to the rotor's output side, with the position detection circuit arranged on the motor cover, maintaining a distance from the electric power conversion circuit to reduce noise interference and improve assembly accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the position detection sensor is installed separately in the motor housing and ECU housing, then the assembly structure is flexible, but the positional assembly accuracy deteriorates
Solution Approach 1:
The patent merges the position detection sensor installation with the motor cover structure. The magneto resistive effect element and position detection circuit are integrated into the motor cover, which is then assembled with the motor housing as a unit. This combining approach maintains the flexibility of separate housing assembly while achieving high positional accuracy through the integrated sensor mounting structure.
Solution Approach 2:
The motor cover serves as an intermediary structure that facilitates both the mechanical assembly and the precise positioning of the detection sensor. By providing a dedicated mounting surface and structure on the motor cover, the patent enables accurate sensor installation while maintaining the modular assembly approach of separate motor housing and ECU housing.
2Device complexity
If the position detection circuit is installed close to the electric power conversion circuit, then the device complexity is reduced, but the detection signal accuracy deteriorates due to switching noise
Solution Approach 1:
The patent extracts the position detection circuit from the ECU housing and relocates it to the motor cover, physically separating it from the electric power conversion circuit. This extraction eliminates the switching noise interference while maintaining relatively simple overall structure through the integrated motor cover design.
Solution Approach 2:
The motor cover acts as an intermediary structure that hosts the position detection circuit at an optimal location - close enough to the rotor for accurate detection but far enough from the power conversion circuit to avoid noise interference. This intermediary structure resolves the conflict between proximity for accuracy and distance for noise reduction.
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 enhances the positional assembly accuracy of the position detection sensor and minimizes the influence of switching noise, resulting in more accurate detection signals.
Implementation Method 1
a magneto resistive effect element constituting a position detection sensor and a position detection circuit for detecting a magnetic pole position are installed in a motor cover
Data Source
AI summary
A position detecting purpose permanent magnet 51 constituting a position detection sensor is installed at an opposite side to an output side of a rotational shaft 45 of a rotor housed within a motor housing 11A. A GMR element 56 which constitutes the position detection sensor and a position detection circuit thereof are installed on a side of a motor cover 48 on which a position detection purpose permanent magnet 51 is arranged. GMR element 56 is arranged on a position opposed against the position detection purpose permanent magnet. Thus, since the GMR element and the position detection purpose permanent magnet is installed, a mutually positioning assembly (attachment) accuracy can be improved. In addition, since the electric power conversion circuit and both of the GMR element and its position detection circuit are kept away, such an effect that an accurate detection signal can be obtained can be achieved.