Rotor Lamination Slot Geometry for Lower Bridge Stress
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Solution Overview
Problem
High-speed operation of rotor laminations in electric machines is limited by mechanical stresses in bridge areas between through-openings and the outer contour, leading to undesirable magnetic leakage fluxes or increased material costs.
Innovation Solution
The rotor lamination design incorporates an equidistant portion along its edge, which reduces mechanical stresses by maintaining a constant distance from the outer contour, allowing for higher speed operation or reduced material usage while minimizing flux leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the distance to the outer diameter is increased for a given through-opening shape, then mechanical stress resistance is improved, but magnetic leakage flux increases
Solution Approach 1:
The invention changes the geometric parameters of the through-opening by introducing an equidistant portion that extends radially outwardly beyond parallel leg sides. This parameter modification allows the opening to maintain adequate mechanical stress resistance while controlling the distance to the outer diameter to minimize magnetic leakage flux.
Solution Approach 2:
The through-opening transitions from a simple linear slot to a three-dimensional form with parallel leg sides connected by an equidistant portion. This dimensional change creates a more efficient stress distribution pattern that reduces mechanical stress concentration without requiring increased distance to the outer diameter.
2Productivity
If higher speed operation is achieved, then productivity is improved, but mechanical stresses in bridge areas increase
Solution Approach 1:
The equidistant portion of the through-opening creates a curved, arc-shaped bridge area between the parallel leg sides and the outer contour. This curvature distributes mechanical stresses more evenly during high-speed rotation, preventing stress concentration that would limit operating speed.
Solution Approach 2:
By modifying the geometry of the through-opening to include an equidistant portion, the invention changes the stress distribution parameters in the bridge areas, enabling the rotor lamination to withstand the centrifugal forces generated during high-speed operation.
3Strength
If material with higher stress resistance is used, then mechanical strength is improved, but manufacturing cost increases
Solution Approach 1:
The invention achieves improved mechanical stress resistance through geometric parameter changes in the through-opening design rather than by changing the material properties. This allows the use of standard, cost-effective materials while still achieving the required strength performance.
Solution Approach 2:
The through-opening is segmented into parallel leg sides and an equidistant portion, creating distinct functional zones that optimize stress distribution. This segmentation allows the structure to achieve high strength without requiring expensive materials.
Data Source
AI summary
A rotor lamination is subdivided into a plurality of equidistant sectors of equal size, each including a first half-sector and a second half-sector separated from the first half-sector by a separation plane. A through-opening is formed in the first half-sector and has a first leg side, of which the imaginary extension intersects the separation plane below a radially outwardly open acute angle, a second leg side, which runs parallel to the first leg side and of which the imaginary extension intersects the separation plane radially further outwards than the imaginary extension of the first leg side, and an edge connecting ends of the leg sides furthest away from the separation plane. A further through opening formed mirror-symmetrically to the first through-opening with respect to the separation plane is formed in the second half-sector, wherein the edge has an equidistant portion equidistant to an outer contour of the rotor lamination.