Rotor Cover Radial Protrusions Fixation
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Solution Overview
Problem
Conventional rotary electric machines in automotive vehicles face issues with the press-fit mounting of rotor shafts and covers, which can lead to accidental disassembly during high-speed rotations and excessive stress due to thermal expansion, necessitating a more secure and stress-free assembly method.
Innovation Solution
A rotor design featuring a cover with radial protrusions that deform a predefined area on the rotor shaft or end plate to create a solid fixation, allowing for a screw-connection type assembly that improves manufacturing and in-service life, using materials with varying hardness such as aluminum and steel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If press-fit mounting is used to assemble the cover on the rotor shaft, then the assembly process is simple, but the fixation is insufficient during high-speed rotations causing accidental disassembly
Solution Approach 1:
The invention replaces the conventional cylindrical press-fit interface with a conical interface where the cover has a conical outer surface that mates with a conical inner surface of the rotor shaft or end plate. The conical geometry provides mechanical interlocking through radial protrusions that deform the softer material, creating a secure fixation that prevents disassembly during high-speed rotation while maintaining ease of manufacture through a single-step assembly process.
2Reliability
If high press-fit efforts are applied to account for thermal shrinking effects, then the fixation security is improved, but undesirable additional stresses are generated
Solution Approach 1:
The invention changes the geometric parameters of the interface from cylindrical to conical, and changes the material parameter relationship by using radial protrusions made of harder material (such as metal) that deform softer predefined areas (such as plastic areas on the end plate or rotor shaft). This deformation creates a mechanical interlock that secures the fixation without requiring high press-fit efforts, thereby avoiding undesirable additional stresses while maintaining thermal expansion compatibility.
3Reliability
If thermal assembly is used to account for thermal shrinking effects, then the fixation security is improved, but the manufacturing process becomes more complex and time-consuming
Solution Approach 1:
The invention replaces the thermal assembly process (heating and cooling cycles) with a mechanical deformation process. Radial protrusions on the conical surface of the cover are made of harder material that deforms softer predefined areas during a single press-fit operation, creating permanent mechanical interlocking. This eliminates the need for thermal processing equipment and multiple heating/cooling cycles, simplifying the manufacturing process while maintaining secure fixation.
4Reliability
If high press-fit efforts are applied to ensure fixation, then the reliability is improved, but the manufacturing cost increases due to higher equipment requirements
Solution Approach 1:
The invention changes the interface geometry to conical and uses differential material hardness with radial protrusions. The protrusions, made of harder material, deform softer predefined areas during assembly, creating mechanical interlocking that secures fixation without requiring high press-fit efforts. This allows the use of simpler, less expensive assembly equipment while maintaining high reliability, thereby reducing manufacturing costs.
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 provides a secure, easy, and cost-effective assembly of the cover on the rotor shaft, preventing accidental disassembly and reducing thermal stresses, thereby enhancing the rotor's manufacturing process and operational life.
Implementation Method 1
said axial portion of the cover comprises at least one row of radial protrusions adapted to deformed said predefined area of the rotor shaft and/or the end plate in order to ensure a fixation between the cover on one side and the rotor shaft and/or the end plate on the other side
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
The invention concerns a rotor for a rotary electric machine, the rotor having an axis of rotation and comprising: - a rotor shaft (5), a rotor body (7) mounted on the rotor shaft (5) and having a plurality of teeth (11), - at least one field coil (10) wound around the plurality of teeth, - at least one end plate (16) configured to come against one axial end of the rotor body (7), - at least one cover (15) mounted on the rotor shaft and having an axial portion (15a, 15b) being in contact with a predefined area (50, 161, 162) of the rotor shaft (5) and/or the end plate (16), wherein said axial portion of the cover (15a, 15b) comprises at least one row of radial protrusions (150) adapted to deformed said predefined area (50, 161, 162) of the rotor shaft (5) and/or the end plate (16) in order to ensure a fixation between the cover (15) on one side and the rotor shaft (5) and/or the end plate (16) on the other side.