Electromechanical Actuator Belt Drive and Temperature Sensing

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Solution Overview

Problem

Existing electromechanical actuators face challenges in achieving a small size and low weight while providing sufficient torque, often requiring heavy gearing that can lead to motor overheating due to stall conditions, which current solutions attempt to mitigate by monitoring current draw rather than temperature.

Innovation Solution

A compact electromechanical actuator design featuring a small, high-speed motor with a gear assembly utilizing a drive belt and worm screw system, incorporating a position sensor and temperature sensor to prevent stall torque and overheating, allowing for efficient torque output without the need for complex gearing and reducing weight.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Weight of moving object

If a small electric motor with high rotational speed is used, then the size and weight of the actuator are reduced, but the output torque becomes insufficient

Engineering Contradiction:
Improveactuator weightVSAvoidoutput torque
Core Design Contradiction:
Weight of moving objectVSForce

Solution Approach 1:

The patent replaces traditional heavy metal gear reduction mechanisms with a belt drive system. The belt transmits rotational motion from the motor to the output shaft, providing torque multiplication without the weight and complexity of conventional gear assemblies. This substitution maintains the benefits of using a small, high-speed motor while achieving the required output torque through the mechanical advantage of the belt pulley system.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Force

If gear reduction is used to increase output torque, then the torque output is sufficient, but the size and weight of the actuator increase

Engineering Contradiction:
Improveoutput torqueVSAvoidactuator weight
Core Design Contradiction:
ForceVSWeight of moving object

Solution Approach 1:

The patent substitutes traditional heavy metal gear reduction mechanisms with a lightweight belt drive system. The belt and pulley arrangement provides the necessary torque multiplication through mechanical advantage while significantly reducing the overall weight and size of the actuator compared to conventional gear-based solutions.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If current draw monitoring is used to detect stall conditions, then the system can protect against overheating, but the detection precision is insufficient compared to direct temperature sensing

Engineering Contradiction:
Improvestall protectionVSAvoidstall detection accuracy
Core Design Contradiction:
ReliabilityVSMeasurement precision

Solution Approach 1:

The patent replaces indirect stall detection through current monitoring with direct temperature sensing using a temperature sensor in thermal contact with the motor. This substitution provides more accurate and reliable stall condition detection by directly measuring the physical parameter (temperature) that indicates motor stress, rather than inferring it from electrical characteristics.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 actuator achieves a smaller size and lower weight with efficient torque output, effectively preventing overheating by monitoring temperature rather than current draw, enhancing reliability and reducing the risk of motor failure.

Implementation Method 1

incorporating a position sensor and temperature sensor to prevent stall torque and overheating

Methodology Applied
Scientific EffectTemperature sensing:

Data Source

PatentEP3325845B1Motor driven electromechanical actuator
Publication Date: 2021.08.04 NATIONAL MACHINERY LLC
  • EP3325845B1 patent drawingFigure 1
  • EP3325845B1 patent drawingFigure 2A
  • EP3325845B1 patent drawingFigure 2B

AI summary

Disclosed is a motor driven electromechanical actuator assembly that generally comprises a motor assembly, a gear assembly, and a circuit board, all of which may be disposed within a housing. The gear assembly includes a plurality of gears, including a belt drive that couples the motor assembly to the actuator output shaft. Moreover, the present actuator assembly may include any number of sensing systems and other features.