Rotary machine unit, compressor, and refrigeration device
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Solution Overview
Problem
The holding force of the stator core in a compressor casing with a non-circular barrel is reduced due to the clearance between the stator core and the casing, leading to potential displacement and stress concentration.
Innovation Solution
A resin layer with a lower Young's modulus than the casing and stator core materials is inserted between the inner peripheral surface of the barrel and the outer peripheral surface of the stator core, increasing the contact area and fixing them through shrink fit, thereby enhancing the holding force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If interference fit is used to fix the stator core in the barrel, then the stator core can be held in position, but the holding force is reduced when the barrel has a non-circular shape due to clearance formation
Solution Approach 1:
A resin layer is introduced as an intermediary substance between the stator core and the barrel. This resin layer fills the clearance formed by the non-circular barrel shape, enabling effective force transmission and maintaining holding force despite manufacturing tolerances in barrel circularity.
Solution Approach 2:
The resin layer's physical properties are utilized to resolve the contradiction. By selecting a resin with appropriate viscosity and curing characteristics, the clearance is filled effectively during assembly, and after curing, the resin maintains constant contact pressure to ensure reliable holding force regardless of barrel shape deviations.
2Reliability
If a resin layer is added to increase contact area and holding force, then reliability improves, but device complexity increases
Solution Approach 1:
A thin resin layer is applied between the stator core and barrel, conforming to the non-circular barrel shape. This thin flexible layer increases the effective contact area without adding significant structural complexity, as it simply fills the clearance rather than requiring additional mechanical components.
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 resin layer increases the holding force of the stator core in the barrel, reducing displacement and stress concentration, even with a non-perfect circular shape, improving motor efficiency and reducing individual variations.
Implementation Method 1
since the resin layer has a lower Young's modulus than those of the casing and the stator core, the resin layer is relatively easily deformed between the inner peripheral surface of the barrel and the outer peripheral surface of the stator core
Implementation Method 2
fixing them through shrink fit, thereby enhancing the holding force
Data Source
Figure 1
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AI summary
A rotary machine unit includes a casing (20) having a tubular barrel (20a), a stator core (61) fixed to an inner peripheral surface of the barrel (20a), and a first member (12) provided between the inner peripheral surface of the barrel (20a) and an outer peripheral surface of the stator core (61). The shape of the inner peripheral surface of the barrel (20a) is a non-perfect circular shape as viewed in the cylinder axis direction of the barrel. The first member (12) is made of a material having a lower Young's modulus than those of a material forming the barrel (20a) and a material forming the stator core (61).