Knurled Stator-Housing Interface for Low-Force Torque Transfer
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Solution Overview
Problem
Existing methods for connecting a stator to a housing in electrical machines face challenges such as increased wall thickness, high press-in forces, risk of cracking, and metal chip damage, while also requiring additional time and cost for heat solidification in adhesive bonding, which hinder compact and efficient design.
Innovation Solution
Implementing a shape deviation, such as knurling, on a partial area of the contact surface between the stator and housing to increase friction, allowing for both non-positive and positive connections without the need for excessive force or adhesives, enabling efficient torque transfer and reduced material usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the stator is pressed into the housing using high pressing forces, then a secure connection is achieved, but the housing wall thickness must be increased to prevent cracking and metallic shavings can be released that may damage the electric motor
Solution Approach 1:
The invention applies a roughening structure (knurling) locally at the contact interface between the stator and housing. This localized surface modification increases friction and mechanical interlocking precisely where needed for connection security, eliminating the need for high pressing forces that would require thicker housing walls.
2Reliability
If the stator is connected to the housing using adhesive bonding, then a secure connection is achieved, but an additional time-consuming curing step and expensive oven equipment are required
Solution Approach 1:
The invention replaces the chemical bonding mechanism (adhesive curing) with a mechanical bonding mechanism (friction and interlocking through knurling). This substitution eliminates the need for thermal curing processes, reducing both time and equipment requirements while maintaining connection security.
3Reliability
If the stator is connected to the housing using a recess and groove design, then torque transmission is achieved, but the housing wall thickness must be increased to accommodate the recess
Solution Approach 1:
The invention concentrates the torque transmission function at the localized knurled contact interface rather than requiring a deep recess. The surface roughening creates sufficient mechanical interlocking and friction for torque transmission without compromising the housing wall thickness.
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 solution allows for a compact and cost-effective electrical machine design with reduced risk of damage, lower material requirements, and efficient assembly, as it enables secure connection with minimal force and no adhesive use, while maintaining structural integrity and thermal conductivity.
Implementation Method 1
at least a partial surface of a contact area between the stator and the housing has a shape deviation to increase the coefficient of friction between the stator and the housing
Data Source
Figure 1
AI summary
The invention relates to a stator-housing unit for an electric machine (10), wherein a stator (1) is connected to a housing (3). A surface deviation is formed on at least one partial surface of a contact surface between the stator (1) and the housing (3), in order to increase the friction coefficient between the stator and housing. According to the invention, the surface deviation is designed as a knurling (4) having preferably axis-parallel striae. Preferably 10% to 30% of the contact surface between the stator (1) and housing (3) is knurled. The invention further relates to a method for producing such a stator-housing-unit for an electric machine (10) and to an electric machine (10) having a stator-housing-unit according to the invention.