Motor Rotor Resin Layer Prevents Centrifugal Peeling

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Solution Overview

Problem

Conventional motor rotors experience resin breakdown and void formation between the cylindrical member and thread layer when rotated at high speeds due to centrifugal forces, leading to potential peeling and cracking of the resin.

Innovation Solution

A motor rotor design featuring a rotary shaft with a permanent magnet layer, a thread layer of reinforced fibers, and a cylindrical member with a resin layer formed by injecting curable resin into the gap between the thread layer and the cylindrical member, ensuring full filling and enhanced adhesion to prevent voids and resin separation at high speeds.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the motor rotor rotates at high speed (not less than 150,000 rpm), then the centrifugal force increases, but the resin with which the thread layer is impregnated is broken and voids are formed between the cylindrical member and the thread layer

Engineering Contradiction:
Improverotation speedVSAvoidresin integrity
Core Design Contradiction:
SpeedVSReliability

Solution Approach 1:

A resin layer is formed on the inner peripheral surface of the cylindrical member before the thread layer is wound around the permanent magnet layer. This preliminary resin layer acts as a protective barrier that prevents the impregnated resin from being broken by centrifugal force during high-speed rotation, thereby maintaining resin integrity at rotation speeds of not less than 150,000 rpm

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The invention uses a composite structure consisting of the cylindrical member, the resin layer, the thread layer impregnated with curable resin, and the permanent magnet layer. This multi-layer composite structure distributes the centrifugal forces across different materials with complementary properties, preventing resin breakdown while maintaining structural integrity at high rotation speeds

Inventive Principle:
Principle #40Composite materials

2Ease of manufacture

If the curable resin with which the thread layer is impregnated is used to bond the threads, then the threads are mutually bonded, but the resin itself is low in strength and peels off under centrifugal force

Engineering Contradiction:
Improvethread bondingVSAvoidresin strength
Core Design Contradiction:
Ease of manufactureVSStrength

Solution Approach 1:

The resin layer formed on the inner peripheral surface of the cylindrical member serves as an intermediary between the cylindrical member and the thread layer. This intermediate resin layer provides enhanced adhesion and structural support, preventing the impregnated resin from peeling off under centrifugal force while maintaining the thread bonding function

Inventive Principle:
Principle #24Intermediary (Mediator)

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 effectively prevents resin peeling and cracking, maintaining structural integrity even at speeds exceeding 150,000 revolutions per minute by ensuring the resin layer adheres strongly to the cylindrical member, thus enhancing the motor rotor's durability and performance.

Implementation Method 1

a resin layer formed of a curable resin which has been injected into the gap and cured... The resin layer that is positively formed only of a curable resin adheres to the cylindrical member with higher adhesion

Methodology Applied
Scientific EffectAdhesion: Adhesive

Implementation Method 2

If the motor rotor rotates at a high speed, however, the plurality of permanent magnets may be broken by a centrifugal force... if the motor rotor is rotated at a high speed and the resin with which the thread layer is impregnated is subjected to a centrifugal force

Methodology Applied
Scientific EffectCentrifugal force: Centrifugal Force

Data Source

PatentEP2091131B1Permanentmagnetrotor for motor and its manufacturing method
Publication Date: 2017.08.09 SANYO DENKI CO LTD
  • EP2091131B1 patent drawingFigure 1
  • EP2091131B1 patent drawingFigure 2A~2B
  • EP2091131B1 patent drawingFigure 3A~3B

AI summary

A motor rotor is provided wherein a resin with which a thread layer is impregnated is preventing from being broken even if the motor rotor is rotated at a high speed. A thread layer 9 is formed by winding a thread of a reinforced fiber material around a permanent magnet layer 5 with a gap formed between an outer peripheral surface 9a of the thread layer 9 and an inner peripheral surface 53a of a cylindrical body 53. The thread layer 9 is impregnated with a curable resin. A subsequent thread layer 13 is formed by leading a continuous thread, which is continuous with the thread forming the thread layer 9, into an annular passage 35 through thread passing recesses 33a, and winding the continuous thread around a bottom portion of the passage 35. The subsequent thread layer 13 is impregnated with a curable resin. A cylindrical member 17 is fixed to first and second annular members 21, 7 by shrink fitting. A curable resin is injected into the gap between the outer peripheral surface 9a of the thread layer 9 and the inner peripheral surface 53a of the cylindrical body 53 through resin injection passages 27a and the thread passing recesses 33a. A curable resin is injected into the gap between an outer peripheral surface 13a of the subsequent thread layer 13 and the inner peripheral surface 53a of the cylindrical body 53 through the resin injection passages 27a. Air bubbles contained in the curable resins are removed through the resin injection passages 27a and the thread passing recesses 33a before the curable resins are heated to be cured.