Linear Rotary Motor Position Sensing Without Rotation Lock
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Solution Overview
Problem
Existing linear rotary motors face challenges in downsizing and simplifying their structure due to the need for long, narrow timing rulers and configurations that prevent mover rotation, leading to increased complexity and size.
Innovation Solution
A linear rotary motor design featuring a cylindrical frame with coaxially arranged linear and rotation coils, a movable and rotatable shaft with a magnet, and integrated position detection using a linear motion scale and detector, allowing for rectilinear and rotational motion without the need for additional rotation prevention mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a timing ruler is provided on the outer periphery of the magnet system extending in the axial direction, then the sensor can detect the timing ruler, but when the mover rotates, the timing ruler cannot be detected by the sensor, requiring additional rotation prevention mechanisms that increase structure complexity
Solution Approach 1:
The linear motion scale is configured to extend in the radial direction (from inner periphery to outer periphery of the magnet system) rather than the axial direction. This dimensional change allows the scale to remain accessible to the sensor regardless of mover rotation, eliminating the need for rotation prevention mechanisms while maintaining detection capability throughout the entire radial length of the scale.
2Measurement precision
If position detectors are collectively disposed on a side opposite to the output shaft, then the detection function is achieved, but the length of the linear rotary motor in the linear motion direction increases, resulting in increased overall motor size
Solution Approach 1:
The position detection system is reconfigured to operate in the radial direction rather than requiring extended axial placement. The linear motion scale extends radially from the inner periphery toward the outer periphery of the magnet system, with the sensor positioned to read the scale from the radial direction. This allows the detector to be disposed on the same side as the output shaft, significantly reducing the motor's length in the linear motion direction while maintaining full detection capability across the entire range of motion.
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 achieves downsizing and simplification of the motor structure by enabling effective position detection over the entire range of motion and rotation, reducing the overall length and complexity of the motor.
Implementation Method 1
a linear motion coil generating a linearly moving magnetic field in a linear motion direction
Implementation Method 2
a rotation coil generating a rotating magnetic field in a rotation direction
Implementation Method 3
the linear motion coil and the rotation coil being energized to cause the mover to move rectilinearly and rotate
Data Source
AI summary
A linear rotary motor includes: a frame; a stator including a linear motion coil and a rotation coil; and a mover including a shaft and a magnet, the shaft including an output shaft. The linear motion coil and the rotation coil is energized to cause the mover to move rectilinearly and rotate. A linear motion detector is disposed on the frame or the stator in such a way as to face the magnet, and detects a position of the mover in a linear motion direction. A linear motion scale is provided on an outer periphery of the mover, the linear motion scale being provided over a range of motion in the linear motion direction and a range of rotation in a circumferential direction so as to face the linear motion detector when the mover moves rectilinearly or rotates.