Miniature PMDC Motor with Cylindrical Commutator for High Power Density
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Solution Overview
Problem
Miniature PMDC motors used in vacuum cleaner brush rollers face challenges in increasing power output without increasing size, which is essential for reducing the motor's weight and allowing access to smaller areas, as they typically have a power output of less than 20 watts with a size of 70 mm×40 mm.
Innovation Solution
A miniature PMDC motor design with a rotor core diameter of 23 mm and 12 poles, a cylindrical commutator with 24 segments, and arcuate permanent magnets, achieving an output power of more than 25 watts, with a compact housing and extended brush length to maintain a low profile and increase motor life, while operating at high speed and voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If the motor size is reduced to decrease weight and improve accessibility, then the motor can access tighter spaces and reduce attachment weight, but the power output decreases below acceptable levels
Solution Approach 1:
The patent changes key parameters including increasing the commutator segment count from typical values to 24 segments, adjusting the rotor core diameter to 23mm±3mm with 12 poles, and optimizing the axial length to 30mm or less. These parameter changes enable the motor to achieve over 25 watts output power in a compact size, resolving the contradiction between size reduction and power maintenance.
Solution Approach 2:
The patent transitions from a conventional rectangular commutator to a cylindrical commutator geometry. This dimensional change allows for more efficient space utilization and improved electrical contact distribution, enabling higher power density in a smaller footprint while maintaining over 25 watts output power.
2Ease of operation
If the motor size is reduced to improve accessibility to tight spaces, then the attachment can reach under low objects, but the power output becomes insufficient for effective brush roller operation
Solution Approach 1:
By optimizing the rotor core diameter to 23mm±3mm and axial length to 30mm or less, the motor achieves a compact cylindrical form factor that can access tight spaces while maintaining over 25 watts power output through the specialized 24-segment cylindrical commutator design.
3Ease of manufacture
If conventional motor design is used to maintain simplicity, then the motor structure remains easy to manufacture, but the power output is limited to less than 20 watts
Solution Approach 1:
The commutator is divided into 24 segments, which is a significant increase from conventional segment counts. This segmentation allows for more precise commutation and higher current handling capability, enabling the motor to achieve over 25 watts power output while maintaining a straightforward manufacturing process using standard brush and commutator assembly techniques.
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 motor achieves a rated output power of 30 watts or more with a reduced size, enhancing cleaning capabilities by allowing access to tighter spaces and maintaining a long operational life of at least 600 hours at 30 watts.
Implementation Method 1
windings wound about the poles of the rotor core and terminated on segments of the commutator
Implementation Method 2
arcuate permanent magnets are located on the inner surface of the arcuate sides
Data Source
AI summary
A small size permanent magnet direct current motor has a housing accommodating a permanent magnet stator and a wound rotor. The rotor has a rotor core with a diameter of 23 mm±3 mm and 12 poles and a cylindrical commutator. The motor has an output power of more than 25 watts.