Rotor Short-Circuiting Pin Insertion with Chamfered Holes
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Solution Overview
Problem
Existing rotors for IPM motors experience strain and hysteresis losses due to the press-fitting of short-circuiting pins, which can lead to damage and reduced magnetic permeability, causing inefficiencies in electric machines.
Innovation Solution
A rotor design featuring a hollow cylindrical rotor core with chamfered or curved corners in pin-receiving holes to facilitate easy insertion of short-circuiting pins, reducing strain and metal shavings, and incorporating first and second plate members to position the pins effectively, thereby maintaining magnetic permeability and reducing hysteresis losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If short-circuiting pins are press-fitted into pin-receiving holes of the rotor core, then the magnetic field is short-circuited effectively, but strain occurs in the pins and rotor core reducing magnetic permeability and increasing hysteresis losses
Solution Approach 1:
The pin-receiving holes are pre-formed with chamfered or curved corners in the steel sheets before assembly. This preliminary action prepares the insertion path to be smooth and guiding, allowing the short-circuiting pins to be inserted without encountering sharp edges that would cause strain. The chamfered corners are created during the steel sheet manufacturing process, ensuring the pins can be inserted smoothly during assembly without damaging the laminated structure or creating excessive strain.
2Reliability
If short-circuiting pins are press-fitted into pin-receiving holes, then magnetic short-circuiting is achieved, but metal shavings are generated that may damage insulating coats and bearings
Solution Approach 1:
The steel sheets are pre-formed with chamfered or curved corners around the pin-receiving holes before the pins are inserted. This preliminary shaping of the hole entrance creates a smooth, rounded insertion path that guides the pins in without creating abrupt contact points. As a result, the pins slide in smoothly without generating metal shavings that could damage the insulating coats of the field coil or the bearings.
3Ease of manufacture
If sharp corners are present in pin-receiving holes, then manufacturing is simpler, but insertion of short-circuiting pins causes strain and damage
Solution Approach 1:
The chamfered or curved corners are incorporated into the steel sheets during the manufacturing process itself, before the sheets are laminated into the rotor core. This preliminary action ensures that when the short-circuiting pins are inserted later, they encounter a smooth, pre-prepared insertion path rather than sharp corners. The chamfering is done as part of the steel sheet fabrication, maintaining manufacturing efficiency while protecting pin integrity.
4Strength
If smooth insertion path is provided for short-circuiting pins, then strain and metal shavings are reduced, but additional processing steps are required
Solution Approach 1:
The formation of chamfered or curved corners in the pin-receiving holes is merged with the existing steel sheet manufacturing process. Rather than adding a separate post-processing step to round the corners, the chamfering is performed during the standard steel sheet fabrication process itself. This merging of operations creates the smooth insertion path without significantly increasing overall manufacturing complexity, as it utilizes existing manufacturing capabilities.
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 enhances the insertion process, minimizing damage and strain, thus maintaining the magnetic properties and efficiency of the electric machine by reducing hysteresis losses and metal shavings, leading to improved rotor performance.
Implementation Method 1
The first and second short-circuiting pins are respectively received in the pin-receiving holes of the rotor core to magnetically short-circuit a magnetic field created by the permanent magnets
Implementation Method 2
The field coil is arranged radially inside the rotor core to cause magnetic flux to flow to the first and second short-circuiting pins via the first and second plate members
Implementation Method 3
The permanent magnets are embedded in the rotor core so as to form a plurality of field poles on a radially outer periphery of the rotor core
Implementation Method 4
The IPM motors can use both reluctance torque and magnet torque
Data Source
AI summary
A rotor includes a rotor core formed by laminating steel sheets, first and second plate members respectively arranged on first and second axial sides of the rotor core, first short-circuiting pins held by the first plate member and having been inserted in respective pin-receiving holes of the rotor core from the first axial side, and second short-circuiting pins held by the second plate member and having been inserted in respective pin-receiving holes of the rotor core from the second axial side. One of the first short-circuiting pins and one of the second short-circuiting pins respectively function as first and second positioning pins. For at least one of first and second positioning pin-receiving holes in which the first and second positioning pins are respectively received, each of the steel sheets forming the rotor core has a chamfered or curved corner around the positioning pin-receiving hole on a positioning pin insertion side.