Motor Encoder Nesting in Hollow Space for Axial Length Reduction
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Solution Overview
Problem
The challenge is to further reduce the size of motors used in devices while maintaining the functionality of encoders for detecting the rotation state of the rotor, as the axial length of motors often increases due to the inclusion of encoders, making it difficult to achieve significant size reduction.
Innovation Solution
A motor design where a stator and rotor are positioned with a clearance, and the encoder is placed within a hollow space defined by the inner peripheral sides of the stator and rotor, allowing at least part of the encoder to be disposed in this space, along with a method of manufacturing that aligns the rotation axis using a jig to optimize the motor's dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If an encoder is provided in the motor to detect rotation state, then the motor can control torque output and number of revolutions, but the axial length of the motor increases
Solution Approach 1:
The encoder is disposed inside the hollow space formed by the rotor and stator, nesting the encoder within the existing motor structure. This allows the encoder to be housed without increasing the overall axial length of the motor, as it utilizes the empty space already present in the motor's cross-sectional area.
Solution Approach 2:
Instead of extending the encoder axially along the rotation axis, the encoder is positioned radially within the hollow space between the rotor and stator. This dimensional repositioning moves the encoder from an axial arrangement to a radial arrangement, preventing axial length increase while maintaining detection functionality.
2Volume of moving object
If the motor size is reduced for device size reduction, then the device becomes more compact, but it becomes difficult to accommodate the encoder without increasing axial length
Solution Approach 1:
The encoder is nested within the hollow space of the motor structure, allowing both the encoder and motor to coexist in a compact configuration. This nesting approach enables small motor size while accommodating the encoder without requiring additional axial space.
Solution Approach 2:
The encoder housing is merged with the motor structure by utilizing the hollow space between the rotor and stator. This combining of functions allows the encoder to be accommodated within the motor's existing volume rather than requiring separate housing space.
3Length of moving object
If the encoder is disposed in the hollow space between rotor and stator, then the axial length is reduced, but precise alignment of the rotation axis becomes critical
Solution Approach 1:
A jig is introduced as an intermediary tool during assembly to ensure precise alignment of the rotation axis with the hollow space. The jig facilitates accurate positioning of the encoder relative to the rotor and stator, compensating for the critical alignment requirements imposed by the compact design.
Solution Approach 2:
Alignment features and positioning structures are built into the motor components during manufacturing to pre-establish the correct rotational alignment. This preliminary preparation ensures that when components are assembled, the rotation axis is properly aligned with the hollow space without requiring complex adjustment procedures.
Data Source
AI summary
A motor is provided to reduce a size of a device more effectively. The motor includes a stator, a rotor that is provided to oppose the stator via a clearance, and an encoder that detects a rotation state of the rotor. A hollow space is provided at an inner peripheral side in comparison with the stator and the rotor, and at least a part of the encoder is disposed in the hollow space.