Rotor Core Keyed Shaft Assembly Without Pin Holes
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Solution Overview
Problem
The existing fastening structure for rotor cores and shafts in dynamo-electric machines can compromise the strength of the rotor due to the application of unnecessary stress and reduced durability against centrifugal forces, particularly when using pin holes and pins to secure the components.
Innovation Solution
A rotor design where the shaft is attached to the rotor core with a clearance fit and a key protruding radially inward from the insertion hole, with the key fitting into a keyway on the shaft, reducing unnecessary stress and eliminating the need for pin holes, thereby enhancing the rotor's strength and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If pin holes are provided in electromagnetic steel sheets and pins are inserted to fasten the rotor core to the shaft, then the fastening between rotor core and shaft is achieved, but the durability strength of the rotor against centrifugal force decreases
Solution Approach 1:
The invention extracts and eliminates the pin holes from the electromagnetic steel sheets. Instead of using pin holes with pins for fastening, the design uses a key-way structure formed directly in the rotor core that receives a key on the shaft, thereby removing the harmful pin holes while maintaining fastening functionality.
Solution Approach 2:
The invention introduces a key as an intermediary element between the shaft and rotor core. The key fits into a key-way in the rotor core and engages with a corresponding feature on the shaft, providing the fastening function without requiring pin holes in the electromagnetic steel sheets.
2Ease of manufacture
If the distal end of the key is opened by pressing the pin into the pin hole, then the key is pressed against the keyway to fasten the shaft and rotor core, but unnecessary stress is applied to the rotor core causing adverse effect on rotor strength
Solution Approach 1:
The invention removes the pin and pin hole mechanism entirely. The fastening is achieved through a interference fit between the key on the shaft and the key-way in the rotor core, eliminating the need to press the distal end of a key into a pin hole and thereby avoiding the transmission of harmful strains to the rotor core.
Solution Approach 2:
Instead of opening the distal end of the key by pressing a pin into a pin hole (conventional method), the invention inverts the approach: the key is pre-formed with a distal end that directly engages with the key-way, and fastening is achieved by pressing the key into the key-way without opening it, thereby avoiding stress concentration and strain transmission to the rotor core.
Data Source
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AI summary
A rotor for a dynamo-electric machine includes a shaft and a rotor core constituted by laminating a plurality of electromagnetic steel sheets, and the rotor core is configured such that the shaft is attached to an inner periphery of the rotor core. Each of the electromagnetic steel sheets constituting the rotor core includes an insertion hole into which the shaft is inserted, and a key protruding radially inwardly from the insertion hole, the shaft includes a keyway formed along an axial direction, the shaft is attached by clearance fit to the insertion holes of the electromagnetic steel sheets, and the key is fitted by pressing into the keyway such that a side face of the key abuts with a side face of the keyway.