Electric Rotating Machine Rotor Contact Area Design
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Solution Overview
Problem
Existing electric rotating machines face challenges in providing a sufficient contact area for electrical connections between center hole conductors and conductors outside the center hole, especially when high currents are involved, which can lead to reduced thermal efficiency and increased shear stress on the shaft.
Innovation Solution
The design includes a rotor with a shaft having a center hole and radial holes for studs, where center hole conductors are inserted and protrude towards the shaft, allowing end conductors to be electrically connected to their side surfaces, providing a larger contact area through slits and bolts that apply pressure to these surfaces for efficient electrical connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the diameter of studs is increased or the number of studs is increased to provide sufficient contact area for high current, then the contact area for electrical connection is improved, but the shaft requires larger holes which reduces shear strength and cannot resist transmission torque
Solution Approach 1:
The invention transitions from a single-point contact (end surface of center hole conductor) to a multi-dimensional contact by forming radial holes that extend from the end surface into the shaft. This creates a contact surface that includes both the end surface and the inner peripheral surface of the radial holes, effectively increasing contact area in multiple spatial dimensions without requiring larger holes that would compromise shaft strength.
Solution Approach 2:
The radial holes are formed within the shaft structure, nesting the electrical connection pathways inside the shaft's radial dimension. This allows the contact surface to utilize the inner walls of these nested holes, providing additional contact area without extending beyond the shaft's outer dimensions or requiring excessive hole sizes that would weaken the shaft.
2Strength
If the diameter of the shaft is increased to increase shearing strength at the end of the rotor, then the shear strength is improved, but the peripheral speed limit of the collector ring restricts further diameter increase
Solution Approach 1:
Instead of increasing shaft diameter in the radial direction (which would increase peripheral speed), the invention utilizes the axial and radial hole depth dimensions to increase contact area. The radial holes extend into the shaft from the end surface, providing additional contact surface area without increasing the shaft's outer diameter, thereby maintaining the peripheral speed limit while achieving the required shear strength.
3Device complexity
If only the end surface area of center hole conductors is used for electrical connection, then the structure is simple, but the contact area is insufficient to accommodate increased current
Solution Approach 1:
The contact surface is segmented into multiple components: the end surface of the center hole conductor and the inner peripheral surfaces of multiple radial holes. This segmentation allows the total contact area to be distributed across several surfaces, accommodating high current through multiple contact zones while maintaining a relatively simple overall structure that integrates with the existing shaft and collector ring configuration.
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 configuration enables efficient and uniform contact surface pressure, increasing the contact area for high current values without the need for significant increases in bolt size or number, thus enhancing thermal efficiency and shear strength.
Implementation Method 1
bolts that apply pressure to these surfaces for efficient electrical connection
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
According to one embodiment, there is provided a gas cooled electric rotating machine in which a cooling gas is flowed through into a rotor (2) and a stator (3). The rotor (2) includes a pair of center hole conductors (211, 221) inserted into a center hole (201) along a center of rotation (L) while being electrically insulated from a shaft (20) and from each other, the center hole conductors (211, 221) including respective protruding parts (211A, 221A) protruding toward an end of the shaft (20). The rotor (2) includes a pair of end conductors (212, 222) provided at the end of the shaft (20) so as to be each electrically insulated from the shaft (20), the end conductors (212, 222) being electrically connected to side surfaces of the protruding parts (211A, 221A) of the pair of center hole conductors (211, 221), the side surfaces serving as electric connection surfaces.