Rotary Electric Machine Recessed Magnet Axial Dimension Reduction
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Solution Overview
Problem
Conventional brushless motors have increased axial dimensions due to permanent magnets protruding from the rotating shaft, hindering size reductions.
Innovation Solution
A rotary electric machine design featuring a recess portion on the rotating shaft's axial end surface, where a magnetism generating body is housed within the bearing, allowing the magnetic sensor to be positioned closer to the end surface, thereby reducing the overall axial dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If permanent magnets are made to protrude completely from the end surface of the rotating shaft toward the angle detecting portion, then the angle detection function is ensured, but the axial dimension of the motor is increased
Solution Approach 1:
The magnetism generating body is nested within a recess portion formed on the axial end surface of the rotating shaft, allowing the magnetic field generation function to be integrated within the shaft structure rather than protruding outward. This nesting approach maintains the necessary magnetic field interaction for angle detection while eliminating the axial space consumption of protruding magnets.
Solution Approach 2:
The design transitions from a conventional protruding magnet configuration (extending in the axial dimension) to a recessed magnet configuration (utilizing the radial depth dimension). By moving the magnetism generating body into the recess portion, the solution addresses the axial dimension constraint by utilizing space in another dimension (radial depth of the recess).
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 design reduces the axial dimensions of the rotary electric machine by accommodating the magnetism generating unit inside the bearing, enabling a more compact structure while maintaining accurate positioning and signal generation for rotational angle detection.
Implementation Method 1
a magnetism generating body that is disposed on an axial end portion of the rotating shaft; and a magnetic sensor that faces the magnetism generating body, the rotational angle detecting apparatus generating a signal that corresponds to a rotational angle of the rotating shaft
Data Source
AI summary
A rotary electric machine includes: a housing; a stator that is disposed in the housing; a rotating shaft that is rotatably disposed in the housing; a rotor that is disposed on the rotating shaft; and a rotational angle detecting apparatus that generates a signal that corresponds to a rotational angle of the rotating shaft. The rotational angle detecting apparatus includes: a magnetism generating body that is disposed on an axial end surface of the rotating shaft; and a magnetic sensor that faces the magnetism generating body. A recess portion is disposed on the end surface. The magnetism generating body is disposed in the recess portion.