Electric Motor Interference-Fit Assembly Using Induction Heating
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Solution Overview
Problem
The existing methods for assembling electric motors, particularly in-wheel motors, are time-consuming and complex due to the need for heating components in an oven to create an interference fit, which complicates the manufacturing process.
Innovation Solution
A method using induction heating to expand the inner surfaces of rotor and stator components, allowing for an interference fit without the need for oven heating, facilitated by robotic arms and precise temperature control to ensure accurate alignment and assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional oven heating is used to create interference fit, then the component can be mounted on the other component, but the assembly process becomes time-consuming and complex
Solution Approach 1:
The patent replaces the traditional mechanical oven heating system with an induction heating system that uses electromagnetic fields to directly heat the component. This substitution eliminates the need for large ovens and manual heating processes, significantly reducing assembly time while maintaining reliable interference fit quality through precise thermal control.
Solution Approach 2:
The invention changes the heating parameters from slow, uniform oven heating to rapid, localized induction heating. By controlling the induction heating parameters (power, duration, position), the system achieves the necessary thermal expansion for interference fit much faster than traditional methods, directly addressing the time loss issue.
2Reliability
If oven heating is used for interference fit, then mounting can be achieved, but the manufacturing process complexity increases
Solution Approach 1:
The patent replaces the complex mechanical oven heating system with a simpler induction heating system. The induction heating apparatus consists of basic electromagnetic components that can be integrated into the assembly line without requiring large heating chambers, complex temperature control systems, or extended heating cycles, thereby reducing manufacturing process complexity.
Solution Approach 2:
The invention applies localized heating to only the specific area requiring interference fit, rather than heating the entire component uniformly as in oven heating. This segmentation of the heating process simplifies the manufacturing setup and allows for more straightforward integration into the assembly line.
3Reliability
If uniform heating is applied to create interference fit, then mounting can be achieved, but time is lost due to heating the entire component
Solution Approach 1:
The patent applies heating only to the local area where interference fit is needed, rather than uniformly heating the entire component. The induction heating system can be positioned to target specific zones, creating thermal expansion only where required for mounting. This localized approach maintains reliable interference fit quality while dramatically reducing the time and energy required for the heating process.
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 approach simplifies the assembly process, reduces time, and ensures secure, uniform connections while maintaining optimal operational characteristics under vibration, thereby enhancing manufacturing efficiency and motor performance.
Implementation Method 1
heating the inner surface of the cylindrical portion of the rotor housing to a temperature which increases the diameter of the inner surface of the cylindrical portion of the rotor housing sufficiently to enable the rotor back iron to fit within the cylindrical portion of the rotor housing
Implementation Method 2
an induction coil which is arranged to heat the inner surface of the cylindrical portion of the rotor housing by electromagnetic induction
Data Source
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AI summary
A method of assembling an electric motor or generator having an annular first element mounted on a circumferential mounting surface of a second element, the method comprising placing a heating coil within an inner annular surface of the annular first element; applying a current to the heating coil to heat the inner annular surface of the annular first element to a temperature that results in the inner annular surface of the annular first element increasing in diameter to allow the annular first element to be mounted on or over the circumferential mounting surface of the second element; and cooling the annular first element to form an interference fit between the annular first element and the circumferential mounting surface of the second element.