Electric Motor Rotor Axial Locking Mechanism

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Solution Overview

Problem

Existing electric brake devices for motor rotors require external lock mechanisms like solenoids and reduction gears, increasing cost and space usage, and necessitating unnecessary components.

Innovation Solution

An electric brake device with a reverse input holder that slides the rotor axially to engage with the housing, eliminating the need for external lock mechanisms by using an electromagnetic force to maintain engagement and retain the rotor's rotation angle.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an external lock mechanism with solenoid and engagement structure is used, then the rotor can be locked, but the device complexity and installation space increase

Engineering Contradiction:
Improverotor locking capabilityVSAvoidlock mechanism structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the locking function with the existing rotor and housing structures by providing an engaging portion on the rotor and an engaged portion on the housing, eliminating the need for separate solenoid and engagement structures. This merging of functions reduces device complexity while maintaining rotor locking capability.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent extracts and eliminates unnecessary external lock mechanism components (solenoid, separate engagement structure) by integrating the locking function directly into the rotor-housing assembly, thereby simplifying the overall device structure.

Inventive Principle:
Principle #2Taking out (Extraction)

2Reliability

If an external lock mechanism with solenoid and engagement structure is used, then the rotor can be locked, but the installation space increases

Engineering Contradiction:
Improverotor locking capabilityVSAvoidinstallation space
Core Design Contradiction:
ReliabilityVSArea of stationary object

Solution Approach 1:

The locking function is merged with the existing rotor and housing components, eliminating the need for separate external lock mechanism components that would occupy additional installation space.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent removes unnecessary external lock mechanism components (solenoid, separate engagement structure) that would increase installation space, retaining only the essential engaging portions integrated into the rotor and housing.

Inventive Principle:
Principle #2Taking out (Extraction)

3Reliability

If a reduction gear is provided for lock mechanism engagement, then the lock can be engaged, but unnecessary components increase cost

Engineering Contradiction:
Improvelock engagementVSAvoidmanufacturing cost
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The patent extracts and eliminates unnecessary reduction gear components by providing direct engagement between the rotor's engaging portion and the housing's engaged portion, thereby reducing manufacturing cost while maintaining lock engagement functionality.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The locking engagement is merged directly between the rotor and housing without requiring intermediate reduction gear components, simplifying the structure and reducing manufacturing cost.

Inventive Principle:
Principle #5Merging (Combining)

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 reduces component count, saves space, and lowers costs by using friction forces to maintain engagement even when power is off, thereby reducing power consumption.

Implementation Method 1

the rotor slider is configured to slide the rotor in the axial direction by an electromagnetic force in the axial direction that acts on the stator and the rotor

Methodology Applied
Scientific EffectElectromagnetic force: Lorentz Force

Implementation Method 2

the friction force generated on the contact surfaces between the engaging portion and the engaged portion keeps the state that the rotor is slid in one axial direction and thereby maintains the engagement

Methodology Applied
Scientific EffectFriction force: Friction

Data Source

PatentEP3503357B1Electric motor device
Publication Date: 2023.01.25 NTN CORP
  • EP3503357B1 patent drawingFigure 1
  • EP3503357B1 patent drawingFigure 2A~2B
  • EP3503357B1 patent drawingFigure 3A~3B

AI summary

When a rotor (8) performs an ordinary rotation operation, an axial position of the rotor (8) is retained such that the rotor (8) is rotatable with respect to a stator (7). When a parking brake switch is operated while a vehicle is at stoppage, a rotor slider slides the rotor (8) in an axial direction against a preload of an axially preloading part (54). This brings an engaging portion (55) of the rotor (8) into engagement with an engaged potion (56) of a housing (4). The reverse input holder retains the rotation angle of the rotor (8) during the engagement due to the fact that the engagement between the engaging portion (55) and the engaged potion (56) is maintained against a reverse input load acting on the rotor (8) as an external force that accompanies a reaction force of a pressing force of a brake friction member.