Damping Coupling for Electric Motor Angle Sensor

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Solution Overview

Problem

Existing angle detection systems for rotor shafts in electric motors are prone to errors due to transverse torque shocks and jerks, which are not effectively suppressed, leading to inaccurate angular position measurements.

Innovation Solution

A coupling system with a damping part between the rotor shaft and the angle sensor, featuring a first and second coupling part connected non-rotatably, where the damping part is elastically deformed to absorb shocks and jerks, and a form-fit connection is established to prevent distortion, ensuring robust operation and precise angle detection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a rigid coupling is used between the rotor shaft and the angle sensor shaft, then the connection is strong and stable, but transverse torque shocks and jerks are transmitted to the angle sensor, causing measurement errors

Engineering Contradiction:
Improveconnection strengthVSAvoidangle measurement precision
Core Design Contradiction:
StrengthVSMeasurement precision

Solution Approach 1:

A damping element is introduced as an intermediary component between the first coupling part (connected to rotor shaft) and the second coupling part (connected to sensor shaft). This damping element absorbs and attenuates transverse torque shocks and jerks, preventing them from reaching the angle sensor while maintaining the mechanical connection. The damping element acts as a mediator that protects the sensitive measurement device from mechanical disturbances.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The damping element is pre-installed between the coupling parts to provide cushioning protection before any shocks or jerks occur. This beforehand cushioning ensures that when transverse torque shocks or jerks are generated during motor operation, they are immediately absorbed by the damping element, preventing measurement errors from the outset.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

2Measurement precision

If a damping element is added between the coupling parts, then transverse torque shocks and jerks are suppressed, but the device complexity increases

Engineering Contradiction:
Improveangle measurement precisionVSAvoidcoupling structure complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The damping element is designed as a flexible component with a simple geometric shape (such as a cylindrical or rectangular element), eliminating the need for complex damping structures. This flexible element can be easily manufactured and integrated into the coupling, providing effective shock suppression without significantly increasing device complexity.

Inventive Principle:
Principle #30Flexible shells and thin films

Solution Approach 2:

The damping element is made from homogeneous damping material with consistent properties throughout, simplifying the design and manufacturing process. This homogeneous structure provides reliable damping performance while maintaining a simple, uncomplicated component design that does not add significant complexity to the overall coupling system.

Inventive Principle:
Principle #33Homogeneity

3Reliability

If the damping element is made from elastic material, then it can deform to absorb shocks, but the connection strength may be reduced

Engineering Contradiction:
Improveshock absorption capabilityVSAvoidconnection strength
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The damping element is designed with optimized geometric parameters (dimensions, shape, positioning) to achieve the right balance between elasticity for shock absorption and sufficient connection strength. By carefully selecting and adjusting these parameters, the damping element provides reliable shock absorption while maintaining adequate mechanical strength to transmit torque and maintain the coupling connection.

Inventive Principle:
Principle #35Parameter changes

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 solution enables error-free angle detection by suppressing transverse torque shocks and jerks, ensuring a robust operation of the angle sensor, even under motor brake or load-induced disturbances, with a high static friction and self-locking mechanism for precise centering and secure connection.

Implementation Method 1

the damping part is elastically deformed to absorb shocks and jerks

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Implementation Method 2

achieve very high static friction, especially with a steel-on-steel material pairing

Methodology Applied
Scientific EffectStatic friction: Static Friction

Data Source

PatentEP3788270B1Electric motor with a coupling between the rotor shaft and the shaft of an angle sensor
Publication Date: 2022.03.23 SEW EURODRIVE GMBH & CO KG
  • EP3788270B1 patent drawingFigure 1
  • EP3788270B1 patent drawingFigure 2
  • EP3788270B1 patent drawingFigure 3

AI summary

An electric motor, having a rotor shaft (15), in particular a rotatably mounted rotor shaft (15) and an angular sensor (6), the angular sensor (6) having a sensor shaft (18) and a housing, wherein: the sensor shaft (18) is connected to the rotor shaft (15) for conjoint rotation therewith by means of a coupling; the coupling has a first coupling part (1), a second coupling part (2) and a damping part (3) positioned between the first coupling part (1) and the second coupling part (2), the damping part being, in particular, in the form of a bushing held in a blind-hole-type cavity of the first coupling part (1); and the first coupling part (1) is connected to the rotor shaft (15) for conjoint rotation therewith and the sensor shaft (18) is connected to the second coupling part (2) for conjoint rotation therewith.