Washing Machine Motor Shield Precision Machining for Alignment
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Solution Overview
Problem
The assembly of brushless permanent magnet electric motors for washing machines faces challenges in achieving precise alignment due to the imprecision of die-cast shields, leading to increased variability and noise in motor performance, particularly evident in domestic washing machines with higher spin cycle speeds.
Innovation Solution
Precision machining of the outer surface of at least one shield, specifically the cylindrical outer surface of the bearing seat, to serve as a precise reference for component positioning and centering during assembly, which can be done using common machine tools without significant design or mold changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If die-casting is used to manufacture shields, then manufacturing ease and cost are improved, but manufacturing precision and alignment accuracy deteriorate
Solution Approach 1:
The shield manufacturing process is segmented into two stages: die-casting for the base structure (maintaining ease of manufacture) and subsequent precision machining of specific reference surfaces (achieving alignment precision). This segmentation allows each process to optimize for its specific purpose.
Solution Approach 2:
Precision machining of reference surfaces is performed as a preliminary action before assembly. By pre-machining the outer surface of the bearing housing and other reference surfaces on the die-cast shields, accurate alignment references are established in advance, enabling precise component positioning during assembly.
2Ease of operation
If larger clearances and tolerances are provided to compensate for alignment imprecision, then assembly ease is improved, but motor performance and noise characteristics deteriorate
Solution Approach 1:
The patent replaces reliance on large mechanical clearances with precision-machined reference surfaces that provide accurate geometric references. This substitution eliminates the need for compensatory clearances while achieving better alignment precision, thereby improving motor performance and reducing noise.
3Manufacturing precision
If precision machining is applied to the outer surface of bearing housing, then alignment precision is improved, but manufacturing complexity increases
Solution Approach 1:
Instead of machining the entire shield, precision machining is applied locally only to specific reference surfaces (outer surface of bearing housing, stator support base, centering reference surfaces). This local quality approach achieves alignment precision while minimizing the impact on manufacturing complexity.
Data Source
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AI summary
To resolve the problem of noise and to reduce the electrical energy consumption of motors for washing machines, the present invention proposes to form, on the outer surface of at least one of the two shields of the motor, an abutment zone that is precision machined so as to allow it to be taken as an exact reference for the positioning and centering of the components in the assembly process of the motor. The most suitable outer surface to meet the needs of the required machining is the outer ring of the bearing housing. In effect, this surface is easily accessible and workable with common machine tools, without requiring tools or work cycles significantly different from the traditional ones.