Brushed Motor Rotor Commutator Press-Fitting Contamination
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Solution Overview
Problem
Conventional methods for press-fitting a commutator onto a rotor are prone to contamination, leading to defects and reduced productivity due to scratches and indentations on the rotor.
Innovation Solution
A rotor design with an inclined surface on the inner circumference of the commutator, where the angle of the inclined surface is smaller than the axial end portion of the knurling, allowing for reduced contamination during press-fitting by ensuring the knurling cuts into the commutator from its extreme distal end.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the commutator is press-fitted onto the knurling of the shaft, then the commutator is securely fixed to the shaft, but contamination occurs at the press-fitting interface causing scratches and indentations on the shaft
Solution Approach 1:
The inner circumferential surface of the commutator is divided into two distinct zones: a first circumferential region with a larger diameter that contacts the knurling during press-fitting, and a second circumferential region with a smaller diameter that contacts the shaft. This segmentation allows the press-fitting contamination to be confined to the first region while protecting the second region from contamination, thus resolving the contradiction between secure fixing and contamination prevention.
2Productivity
If the inner diameter of the commutator is tapered to reduce initial rupture and improve productivity, then molding workability and coaxial accuracy are improved, but contamination during press-fitting is not addressed
Solution Approach 1:
Different regions of the commutator's inner circumferential surface are given different diameters to serve different functions. The first circumferential region has a larger diameter optimized for press-fitting operations, while the second circumferential region has a smaller diameter optimized for contact with the shaft. This local quality differentiation allows productivity improvements through tapered design while simultaneously addressing contamination by isolating the press-fitting zone.
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 effectively minimizes contamination and defect factors during press-fitting, enhancing productivity and coaxial accuracy between the commutator and shaft.
Implementation Method 1
fastening of a commutator and a shaft of a rotor is in many cases carried out using a method of providing a knurling on the shaft and press-fitting the commutator onto the knurling
Data Source
AI summary
Provided is a rotor of a brushed motor capable of reducing the occurrence of contamination during press-fitting of a commutator onto a knurling and reducing defect factors due to rotor contamination to improve productivity. In a rotor of a brushed motor having a commutator press-fitted onto a knurling of a shaft, an inclined surface is provided on an inner circumferential side of the commutator, and an angle of the inclined surface is configured to be smaller than an angle of an axial end portion of the knurling. The knurling may be configured to be at a position different from a shaft stepped end surface of the shaft and the knurling may be configured to be positioned axially inward of the commutator from an end surface of the commutator.