Rotary Electric Machine Housing Tapered Split Cylinder Press Fit
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Solution Overview
Problem
Conventional rotary electric machine housings face challenges in securing the stator against torque reaction and inertial forces due to vibrations, and in achieving efficient cooling, particularly with increased lamination thickness and electric current, which leads to higher press fitting forces and production costs.
Innovation Solution
A rotary electric machine housing with an internal cylinder having a tapered face on its outer diameter and an external cylinder with a tapered face on its inner diameter, allowing for reduced press fitting force and enhanced cooling through a multi-step press fitting process and integrated coolant ducts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the thickness of the laminated stator is increased to achieve higher output, then the output of the rotary electric machine is improved, but the shrink fitting time and press fitting distance increase, requiring upsized equipment and reducing production efficiency
Solution Approach 1:
The housing is divided into a two-way split center housing with front and rear housing segments. The stator is press-fitted into this split housing structure, which allows the stator to be secured without requiring excessive press fitting force or distance, thereby maintaining production efficiency while supporting higher output requirements through increased lamination thickness
2Power
If the thickness of the laminated stator is increased to achieve higher output, then the output of the rotary electric machine is improved, but the press fitting force increases, necessitating upsized press fitting equipment
Solution Approach 1:
The split center housing structure divides the press fitting process into manageable segments, allowing the stator to be press-fitted into the housing without requiring excessive force. The segmented housing provides distributed support that reduces the peak press fitting force needed while accommodating thicker laminated stators for higher output
3Power
If an increased amount of electric current flows in the rotary electric machine to achieve higher output, then the output is improved, but the amount of heat generated at the stator conductor increases, requiring forced cooling
Solution Approach 1:
A coolant duct is introduced as an intermediary cooling mechanism within the housing structure. The coolant duct enables forced cooling of the stator conductor by circulating coolant through the housing, effectively managing the increased heat generation that results from higher electric current flow required for higher output
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 solution reduces the press fitting force required and enhances cooling efficiency, addressing the issues of stator security and production costs while maintaining a compact design.
Implementation Method 1
an internal cylinder 10 allowing press fitting of a stator 20 along an inner diameter end of the internal cylinder 10. The internal cylinder 10 has an internal cylinder-side tapered face on its outer diameter end surface. A rotary electric machine housing according to a first aspect of the present invention includes an internal cylinder 10 allowing press fitting of a stator 20
Implementation Method 2
Placing the entire outer perimeter of the stator into contact with the inner perimeter of the center housing maximizes the contact area through which heat generated at the stator conductor is transferred to the center housing
Implementation Method 3
Another structure for coolant-use forced cooling is proposed, as disclosed in PTL 3. This structure includes a concave coolant duct provided on the outer perimeter of a center housing and a cylindrical cover provided as an outer casing on the outer perimeter of the center housing
Data Source
AI summary
Provided is a rotary electric machine housing and a rotary electric machine equipped with the same. The housing allows the reduction of press fitting force required in each of two press fitting steps and has a high cooling effect. This rotary electric machine housing includes an internal cylinder 10 allowing press fitting of a stator 20 along an inner diameter end of the internal cylinder. The internal cylinder 10 has an internal cylinder-side tapered face on its outer diameter end surface. The housing further includes an external cylinder 11 having an external cylinder-side tapered face on an inner diameter end of the external cylinder. The external cylinder-side tapered face fits onto the internal cylinder-side tapered face. It is preferred that an inner diameter of the internal cylinder be smaller than an outer diameter of the stator; an outer diameter of the internal cylinder be larger than an inner diameter of the external cylinder; and a difference between the outer diameter of the internal cylinder and the inner diameter of the external cylinder be larger than a difference between the inner diameter of the internal cylinder and the outer diameter of the stator.