Force Sensor Sealing Against Liquid and Dust

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Solution Overview

Problem

Force sensors used in environments with liquids and dust, such as robot arms, face the challenge of liquid and dust entering through gaps between the main body and movable parts, compromising reliability.

Innovation Solution

A force sensor design featuring a cylindrical main body and movable body with circular openings, strain body, and stoppers to prevent excessive deformation, along with sealing members to cover the openings and maintain a precise gap for protection against liquids and dust.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If the force sensor is designed with a gap between the main body and movable body for movement, then the movable body can move with respect to the main body, but liquid and dust can enter the inside through the gap

Engineering Contradiction:
Improvemovability of movable bodyVSAvoidprotection against liquid and dust
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The patent applies sealing members (flexible membranes) that cover the movable body while allowing it to move relative to the main body. These flexible membranes create a barrier against liquid and dust penetration while maintaining the necessary movability of the movable body for force detection operations.

Inventive Principle:
Principle #30Flexible shells and thin films

2Reliability

If sealing members are added to cover openings and prevent liquid entry, then protection against liquid and dust is improved, but device complexity increases

Engineering Contradiction:
Improveprotection against liquid and dustVSAvoidstructure with sealing members
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The sealing members serve multiple functions simultaneously: they seal the gaps between the main body and movable body to prevent liquid and dust entry, while also allowing the movable body to move for force detection. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 effectively prevents liquid and dust from entering the sensor, enhancing its reliability and safety by managing the clearance between components with high accuracy, thus protecting the strain body from damage and improving the sensor's operational integrity.

Implementation Method 1

a strain body fixed to the main body and the movable body and deformable according to the movement of the movable body

Methodology Applied
Scientific EffectDeformation: Deformation

Implementation Method 2

deformation of the strain body is converted into an electrical signal by a strain sensor (strain gage)

Methodology Applied
Scientific EffectStrain sensor conversion: Piezoresistive Effect

Data Source

PatentEP3594648B1Force sensor
Publication Date: 2023.04.19 NIDEC COPAL ELECTRONICS CORPORATION
  • EP3594648B1 patent drawingFigure 1~2
  • EP3594648B1 patent drawingFigure 3
  • EP3594648B1 patent drawingFigure 4

AI summary

A force sensor capable of preventing liquid and dust from entering an inside through a gap between a main body and a movable body, and improving reliability is provided. In a force sensor 10B according to one embodiment, a main body 11 is cylindrical. A cylindrical movable body 12 is movable with respect to the main body and includes at least three circular openings in the outer circumference thereof. A strain body 16 is fixed to the main body and the movable body and is deformable according to the movement of the movable body. Strain sensors 16a are provided on the strain body. A first stopper 14 is arranged inside each of the openings and includes a first outer circumferential surface including a first outer diameter less than a diameter of the opening. Sealing members 40 are configured to cover at least the openings and a movable part between the main body and the movable body.