Electric Machine Rotor Gap Filled with Plastic
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Solution Overview
Problem
Electrical machine rotors, particularly in motor vehicles, face mechanical stress issues due to press fits and torque transmission, leading to reduced service life and increased production costs when using high-strength materials, and complex assembly challenges with positive fits.
Innovation Solution
A rotor design featuring a gap between protrusions on the disk pack and grooves on the rotor carrier, filled with injection-moldable plastic, which reduces mechanical stresses and allows for easier assembly, enhancing mechanical stability and service life while avoiding the complexities of press fits and positive fits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a press fit connection is used between the disk pack and rotor carrier, then torque transmission is achieved, but mechanical stresses in the disk pack and laminations increase, reducing service life
Solution Approach 1:
The patent introduces plastic material as an intermediary substance between the disk pack and rotor carrier. This plastic fills the gap and provides torque transmission through adhesive bonding rather than direct mechanical contact, eliminating the harmful press fit stresses while maintaining the required torque transmission capability.
Solution Approach 2:
The patent replaces the mechanical press fit connection system with a chemical adhesive bonding system using plastic. This substitution eliminates the mechanical stresses caused by interference fitting while maintaining effective torque transmission through the bonded joint.
2Strength
If high-strength materials are used for the disk pack to withstand mechanical stresses, then torque transmission capability is improved, but production costs increase
Solution Approach 1:
By introducing plastic as an intermediary bonding agent, the patent eliminates the need for high-strength disk pack materials. The plastic absorbs the torque transmission function, allowing the use of standard, cost-effective materials for the disk pack while maintaining adequate strength through the adhesive bonding mechanism.
3Manufacturing precision
If a positive fit connection is used between the disk pack and rotor carrier, then assembly precision is improved, but assembly complexity increases
Solution Approach 1:
The plastic material serves as a compensating intermediary that fills gaps and accommodates dimensional variations between the disk pack and rotor carrier. This eliminates the need for tight tolerances and complex alignment procedures required by positive fit connections, simplifying the assembly process while maintaining adequate positioning accuracy.
4Quantity of substance
If the gap between protrusion and groove is reduced to minimize plastic material, then material usage is optimized, but mechanical stability may be compromised
Solution Approach 1:
The patent optimizes the gap dimensions and plastic material properties to achieve the right balance. By carefully selecting the gap size and using plastic with appropriate adhesive strength and mechanical properties, the design achieves adequate mechanical stability with minimized material usage, avoiding both excessive material consumption and insufficient bonding strength.
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 design increases mechanical stability, robustness, and service life by reducing mechanical stresses and simplifying assembly, allowing for higher operational speeds and reduced production costs.
Implementation Method 1
the gap being completely filled with an injection-moldable plastic, so that the disk pack is rotatably connected to the rotor arm
Implementation Method 2
in one Plastic injection molding process and / or a transfer molding process can be filled
Implementation Method 3
the injection-mouldable plastic can be characterized in that it can harden relatively quickly and, in the hardened state, has high mechanical stability or strength and high temperature resistance
Data Source
Figure 1
Figure 2~3
AI summary
A rotor (14) for an electric machine (10) and an electric machine (10) are disclosed. The rotor (14) has a rotor support (24) and at least one laminated core (16) comprising laminations (18) stacked over one another in the longitudinal extension direction of the rotor (14), wherein the laminated core (16) is arranged coaxial to the rotor support (24) and completely surrounds the rotor support (24) on an outer circumference of the rotor support (24). The laminated core (16) has at least one projection (26) on an inner circumference, and the rotor support (24) has at least one groove (28) on the outer circumference, which groove is designed to cooperate with the projection (26) of the laminated core (16). The rotor (14) according to the invention is characterized in particular in that the projection (26) of the laminated core (16) and the groove (28) of the rotor support (24) are spaced apart from one another via a gap (32) in order to facilitate an assembly of the rotor (14), wherein the gap (32) is completely filled with an injectable plastic material (34) so that the laminated core (16) is rotationally fixed to the rotor support (24). All together, this can simplify manufacturing of the rotor (14) and increase a load-bearing capacity of the rotor (14).