DC Motor Rotation Detection Unit in End Cover
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Solution Overview
Problem
Existing DC motors face challenges in accurately controlling the velocity or position of the rotor due to space constraints when integrating a rotation detection unit, which is necessary for applications like autofocus lenses, where precise rotation detection is required.
Innovation Solution
A miniaturized DC motor design that integrates a rotation detection unit within the motor's structure, eliminating the need for additional space by arranging the detection unit between the brushes or on the rotor shaft, using various location detection devices such as reflectors, magnets, or capacitive/inductive sensors to detect rotation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a rotation detection unit is installed in the gear unit, then rotation detection function is achieved, but space in lengthwise direction is required which hinders miniaturization
Solution Approach 1:
The rotation detection unit is merged with the end cover structure. The detection unit is installed in the end cover rather than in the gear unit, combining the protective housing function with the detection function. This integration eliminates the need for separate detection unit space in the lengthwise direction while maintaining rotation detection capability.
Solution Approach 2:
The detection unit is arranged in the radial direction within the end cover rather than extending the motor in the axial direction. By utilizing the radial space in the end cover, the design achieves rotation detection without increasing the motor's lengthwise dimension, effectively transitioning the space utilization from axial to radial arrangement.
2Measurement precision
If a rotation detection sensor unit is added to the DC motor, then accurate control of rotor velocity or position is achieved, but device complexity increases
Solution Approach 1:
The rotation detection unit is combined with the end cover assembly, merging two functional elements (detection and housing) into one integrated structure. This reduces the number of separate components and simplifies the overall motor structure while maintaining accurate rotation detection capability for rotor velocity and position control.
Solution Approach 2:
The end cover is designed to serve multiple functions: it provides structural housing protection, supports brush assembly, and integrates the rotation detection unit. This multi-functionality reduces the need for additional separate components, thereby decreasing device complexity while achieving accurate rotor control.
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 allows for reduced product size, simplified modularization of the motor driving unit, and decreased manufacturing costs by eliminating the need for external space for the detection unit, while enhancing assembly efficiency and accuracy of rotation detection.
Implementation Method 1
The at least one location detection device may include one or more reflectors arranged at regular intervals along a circumferential direction of the cover unit
Implementation Method 2
The at least one location detection device may include permanent magnets that have an N pole and an S pole and are alternately arranged along a circumferential direction of the cover unit
Implementation Method 3
The at least one location detection device may include one or more protrusions formed of conductors and arranged on a surface of the cover unit along a circumferential direction of the cover unit
Implementation Method 4
The at least one location detection device may include metallic and non-metallic materials alternately arranged along a circumferential direction of the cover unit
Implementation Method 5
The rotation detection unit may include a light source and a light reception unit
Implementation Method 6
The at least one location detection device may include one or more slits arranged at regular intervals along a circumferential direction of the cover unit
Data Source
AI summary
A direct current (DC) motor including: a cylindrical frame, at least one end of which is open; a cylindrical end cover including an opening configured to block the at least one open end; a rotor including a rotor shaft supported by the frame and the end cover, and a rotor core installed on the rotor shaft; a commutator installed on the rotor shaft and arranged on one end of the rotor core; a cover unit installed on the rotor shaft, arranged between the rotor and the commutator, and including at least one location detection device; and a rotation detection unit installed in the end cover and configured to detect the at least one location detection device.