DC Motor Rotor Insulation via Integrated Resin Collar
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Solution Overview
Problem
Resin rotor shafts in DC motors lack rigidity and heat resistance, and existing methods for insulating metal rotor shafts from electromagnetic coil windings are complex and prone to process management issues, such as rough surfaces and detachment during assembly.
Innovation Solution
A DC motor design featuring a rotor with a resin cylindrical member and an annular collar integrated through apertures in the rotor shaft, which provides insulation between the rotor shaft and electromagnetic coil windings, allowing for simpler manufacturing and reduced stress on the coils.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If insulating coating is applied to the rotor shaft prior to mounting, then insulation between windings and rotor shaft is achieved, but the process sequence becomes complicated and the rotor shaft surface becomes rough preventing press fitting
Solution Approach 1:
The patent introduces a resin cylindrical member as an intermediary component between the metal rotor shaft and the electromagnetic coil windings. This mediator provides the necessary insulation function while maintaining a smooth rotor shaft surface for press fitting, avoiding the need to apply insulating coating directly to the rotor shaft.
Solution Approach 2:
The patent divides the insulation function from the rotor shaft itself by introducing a separate resin cylindrical member. This segmentation allows the rotor shaft to maintain its mechanical properties (smooth surface for press fitting) while the resin member provides the insulation function, simplifying the overall process sequence.
2Reliability
If heat-shrinkable tube is mounted to the rotor shaft for insulation, then insulation is achieved and process sequence is flexible, but additional components and complicated mounting work are required
Solution Approach 1:
The patent combines the insulation function with the existing rotor core structure by integrating the resin cylindrical member into the rotor assembly. This merging approach eliminates the need for separate heat-shrinkable tubes while achieving the same insulation effect, reducing both component count and assembly complexity.
Solution Approach 2:
The resin cylindrical member serves multiple functions: it provides electrical insulation between the metal rotor shaft and windings, maintains structural integrity, and facilitates the press-fit assembly process. This multi-functionality replaces the specialized heat-shrinkable tube with a more versatile component.
3Strength
If metal rotor shaft is used, then rigidity and heat resistance are improved, but electric conduction between windings and rotor shaft occurs causing short circuit
Solution Approach 1:
The patent applies local quality by using a metal rotor shaft for the portion requiring strength and heat resistance, while introducing a resin cylindrical member at the specific location where electrical insulation is needed. This allows each material to be used where its properties are most beneficial.
Solution Approach 2:
The patent creates a composite structure combining metal rotor shaft and resin cylindrical member. The metal provides mechanical strength and heat resistance, while the resin provides electrical insulation, achieving a synergistic combination of properties that neither material could provide alone.
Data Source
AI summary
A collar is provided on the outer periphery of a rotor shaft and is integrated with a cylindrical member through apertures penetrating the outer wall of the rotor shaft.