Rotor Lamination Spring Tongues Torque Transmission
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Solution Overview
Problem
Existing methods for connecting laminations to a rotor shaft in electric motors fail to achieve a torque-transmitting, backlash-free connection while maintaining low manufacturing costs, often requiring tight tolerances and high machining efforts.
Innovation Solution
The use of spring tongues in the laminations' inner passage, which are braced with a counter-geometry on the shaft, creating a force fit that complements the form fit to transmit large torques and maintain a backlash-free connection, even under alternating loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If resilient tabs are used to center laminations on the shaft, then the laminations can be assembled without tight tolerances, but large torques cannot be transmitted between the laminations and the shaft
Solution Approach 1:
The connection function is segmented into two independent mechanisms: resilient tabs for centering and positioning, and circumferential bracing elements (keys or grooves) for torque transmission. This segmentation allows each mechanism to be optimized independently - the resilient tabs provide assembly ease with loose tolerances, while the bracing elements provide the necessary torque capacity without interfering with the centering function.
Solution Approach 2:
The resilient tabs act as an intermediary element that provides the form fit for centering, while a separate bracing mechanism (key or groove) acts as an intermediary for torque transmission. This intermediary approach allows the two functions to be decoupled, enabling loose tolerances for assembly while maintaining high torque transmission capacity through the bracing mechanism.
2Strength
If a cylindrical press fit is used to fasten disks on the shaft, then a torque-transmitting connection is achieved, but tight tolerances and high machining effort are required
Solution Approach 1:
The connection function is segmented into two independent mechanisms: resilient tabs for centering and positioning, and circumferential bracing elements (keys or grooves) for torque transmission. This segmentation allows each mechanism to be optimized independently - the resilient tabs provide assembly ease with loose tolerances, while the bracing elements provide the necessary torque capacity without interfering with the centering function.
Solution Approach 2:
The connection mechanism transitions from a single press-fit interface requiring tight tolerances to a two-stage mechanism: first, resilient tabs provide form fit with loose tolerances for easy assembly; second, circumferential bracing elements engage to provide torque transmission. This parameter change in the connection approach eliminates the need for tight tolerances while maintaining torque capacity.
3Ease of manufacture
If a form fit is formed between the disks and shaft with a recess, then manufacturing costs are reduced, but backlash-free transmission of alternating torques cannot be achieved
Solution Approach 1:
The connection function is segmented into two independent mechanisms: resilient tabs for centering and positioning, and circumferential bracing elements (keys or grooves) for torque transmission. This segmentation allows each mechanism to be optimized independently - the resilient tabs provide assembly ease with loose tolerances, while the bracing elements provide the necessary torque capacity without interfering with the centering function.
Solution Approach 2:
The connection system uses a composite approach combining two different mechanical interfaces: the resilient tabs create a form fit for positioning, while the circumferential bracing elements (keys or grooves) create a positive mechanical interlock for torque transmission. This composite connection system achieves both cost-effective manufacturing and reliable backlash-free torque transmission.
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 enables the secure, circumferentially braced attachment of laminations to the shaft, allowing for the transmission of large torques without deflection, while avoiding the need for tight tolerances and reducing production costs.
Implementation Method 1
resilient attachments of the lamellas, which are in the inner passage of the laminations, deform elastically in the axial direction and create indentations on the surface of the shaft
Implementation Method 2
the lamellae have spring tongues formed in the inner passage, which are braced with a bracing force in the circumferential direction with at least one counter-geometry formed on the shaft
Data Source
Figure 1~2
Figure 3~5
Figure 6~7
AI summary
A rotor for an electric motor may include a shaft and a plurality of disks that are received on the shaft. The disks may include an inner passage, through which the shaft is guided, with the result being that the disks are centered on the shaft via the inner passage. The plurality of disks may have spring tongues that are configured in or along the inner passage and are braced with a bracing force in a circumferential direction against at least one mating geometry that is configured on the shaft.”