Rotating Electric Machine Sensor Shielding
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Solution Overview
Problem
Conventional rotating electric machines face issues with electromagnetic noise affecting rotation-position detection units due to rapid current changes, and existing shielding methods are mechanically fragile and prone to positional deviations, leading to variations in performance and shielding effectiveness.
Innovation Solution
A rotating electric machine design featuring a ring-shaped member with a non-magnetic, conductive unit that forms a magnetic circuit to reduce magnetic field changes and enhance shielding, combined with a robust positioning mechanism to maintain the sensor unit's accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a shielding member made of magnetic material is used to cover the rotation-position detection unit, then the shielding effect against electromagnetic noise is improved, but the mechanical strength is reduced and positional deviation occurs
Solution Approach 1:
The patent employs a composite structure consisting of a non-magnetic material base (such as aluminum or aluminum alloy) combined with a magnetic material layer (such as ferrite or permalloy) coated on its inner surface. This composite shielding member maintains high mechanical strength from the non-magnetic base while the magnetic material layer provides effective shielding against electromagnetic noise through its magnetic properties.
2Object-affected harmful factors
If the shielding member is positioned close to the rotation sensor unit for effective shielding, then the noise reduction is improved, but the detection accuracy is adversely affected due to magnetic field interference
Solution Approach 1:
The patent applies magnetic material selectively only on the inner surface of the non-magnetic shielding member that faces the rotation sensor unit, rather than using magnetic material throughout the entire structure. This localized application of magnetic material provides effective noise shielding in the critical region while minimizing magnetic field interference with the sensor operation.
3Ease of operation
If an opening is provided in the shielding member for signal line passage, then the ease of operation is improved, but the shielding performance is deteriorated due to magnetic flux intrusion
Solution Approach 1:
The patent introduces a magnetic seal structure (such as a C-shaped magnetic seal or magnetic grommet) as an intermediary component at the opening where the signal line passes through the shielding member. This magnetic seal maintains the shielding effectiveness by providing a magnetic path that prevents magnetic flux intrusion while allowing the signal line to pass through.
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 interference with the rotation sensor unit, enhances detection accuracy, and maintains high mechanical strength, thereby improving the overall control precision and productivity of the rotating electric machine.
Implementation Method 1
a ring-shaped member provided with a non-magnetic unit having an electric conductivity and a magnetic unit is fixed on the outer periphery of the rotation sensor unit
Implementation Method 2
thereby changes in a magnetic field due to switching operation of the switching element hardly reach the rotation sensor unit
Data Source
AI summary
There is provided a rotating electric machine including a rotation sensor unit capable of demonstrating a shielding effect over a wide frequency bandwidth and a manufacturing method therefor. In the rotating electric machine, a power unit provided with a switching element that controls an electric current that flows in a stator winding and a magnetic-field current control circuit unit provided with a switching element that controls an electric current that flows in a rotor winding are arranged on a predetermined surface of one of a pair of brackets that pivotably support a rotor shaft, and the rotation sensor unit is disposed in the vicinity of the predetermined surface of the one bracket; The rotating electric machine is characterized in such a way that there is provided a ring-shaped member that is fixed on the outer surface of the rotation sensor unit, and the ring-shaped member is configured with a non-magnetic unit having an electric conductivity and a magnetic unit.