Electric Compressor Boss Structure to Limit Bearing Distortion
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Solution Overview
Problem
The downsizing of electric compressors leads to challenges in ensuring sufficient space for the boss, resulting in asymmetrical shapes with varying wall thicknesses, which causes deformation and distortion of the bearing, reducing durability and leading to noise due to rotary shaft runout.
Innovation Solution
The electric compressor design includes a boss with an asymmetrical shape and varying distances from the inner peripheral surface, allowing the rotary shaft to be press-fitted with a clearance, which supports the bearing and reduces distortion, enhancing durability and quietness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the housing diameter is decreased to downsize the electric compressor, then the compactness is improved, but the space for the boss becomes insufficient, leading to asymmetrical shape and non-uniform wall thickness
Solution Approach 1:
The patent accepts and utilizes the asymmetrical shape of the boss as a result of downsizing constraints. Rather than attempting to maintain symmetry, the design adapts to the asymmetrical configuration caused by the reduced housing diameter, allowing the boss to have varying wall thicknesses while still fulfilling its structural function of supporting the bearing.
2Ease of manufacture
If the bearing is press-fitted into the boss with non-uniform wall thickness, then the assembly is simplified, but the boss deforms and distorts during press-fitting, reducing bearing durability
Solution Approach 1:
The patent applies local quality by providing reinforcement ribs at specific locations on the boss where needed to prevent deformation during press-fitting. Rather than uniformly thickening the entire boss structure, the reinforcement is localized to critical areas that experience the most stress during the press-fitting process, thus preventing distortion while maintaining the overall asymmetrical design.
3Strength
If the boss wall thickness is increased to prevent deformation, then the structural strength is improved, but the available space in the housing is further reduced, limiting downsizing
Solution Approach 1:
The patent segments the boss structure by adding reinforcement ribs that divide the wall into multiple sections. These ribs provide localized structural support to prevent deformation during press-fitting without requiring a uniform increase in wall thickness throughout the entire boss. This segmentation approach strengthens critical areas while minimizing the overall material usage and space occupation.
4Ease of manufacture
If the bearing is distorted due to boss deformation, then the manufacturing process is simpler, but the rotary shaft runout increases, causing noise
Solution Approach 1:
The reinforcement ribs are strategically positioned at locations that experience the most stress during press-fitting to prevent localized deformation that would cause bearing distortion and subsequent shaft runout. This localized reinforcement maintains the simplicity of the press-fitting process while eliminating the harmful noise generated by improper bearing alignment.
Data Source
AI summary
An electric compressor includes a housing, a rotary shaft rotatably supported in the housing, a motor that rotates the rotary shaft, and a compression part that compresses fluid. The housing includes a boss protruding toward the motor, and the boss has an inner peripheral surface in which a bearing that supports the rotary shaft is provided. The boss has an asymmetrical shape and has an outer peripheral surface that varies in distance from the inner peripheral surface in a radial direction of the rotary shaft. The rotary shaft is press-fitted in the bearing, and the bearing is fitted in the inner peripheral surface with a clearance between the bearing and the inner peripheral surface.