Webbing Take-up Device Centrifugal Clutch Control

Solution Overview

Problem

Centrifugal clutches in webbing take-up devices experience excessive load due to inertial force in addition to centrifugal force, leading to durability issues and increased operational noise.

Innovation Solution

A webbing take-up device with a controller that applies a first voltage lower than the target voltage to operate the centrifugal clutch, followed by the target voltage, to distribute the load and prevent excessive inertial force from contributing to the operational load.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the target voltage is applied directly to the motor to operate the centrifugal clutch, then the clutch operates reliably, but excessive load arises due to inertial force

Engineering Contradiction:

Improvecentrifugal clutch operation reliabilityVSAvoidload on centrifugal clutch

Core Design Contradiction:

ReliabilityVSForce

Solution Approach 1:

The controller applies a first voltage to the motor before applying the target voltage. This preliminary action allows the motor to start rotating and gradually build up speed, so that when the target voltage is applied, the inertial force is reduced and the load on the centrifugal clutch is minimized while still ensuring reliable operation.

Inventive Principle:

Principle #10Preliminary action

2Productivity

If the target voltage is applied directly to the motor, then the webbing take-up operates quickly, but operational noise increases due to excessive load

Engineering Contradiction:

Improvewebbing take-up speedVSAvoidoperational noise

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The controller applies a first voltage to the motor before applying the target voltage. This preliminary action allows the motor to start rotating and gradually build up speed, so that when the target voltage is applied, the inertial force is reduced and the load on the centrifugal clutch is minimized, thereby reducing operational noise while still ensuring efficient webbing take-up.

Inventive Principle:

Principle #10Preliminary action

3Loss of time

If the target voltage is applied directly to the motor, then the response time is short, but durability of the centrifugal clutch decreases

Engineering Contradiction:

Improveresponse timeVSAvoidcentrifugal clutch durability

Core Design Contradiction:

Loss of timeVSDuration of action of stationary object

Solution Approach 1:

The controller applies a first voltage to the motor before applying the target voltage. This preliminary action allows the motor to start rotating and gradually build up speed, so that when the target voltage is applied, the inertial force is reduced and the load on the centrifugal clutch is minimized. This extends the durability of the centrifugal clutch while maintaining acceptable response time for webbing take-up operation.

Inventive Principle:

Principle #10Preliminary action

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 approach reduces the necessary load on the centrifugal clutch, enhancing durability and reducing operational noise by ensuring only the centrifugal force is necessary for operation.

Implementation Method 1

a motor that is able to operate a centrifugal clutch

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

the centrifugal clutch is operated utilizing centrifugal force

Methodology Applied

Scientific EffectCentrifugal force: Centrifugal Force

Data Source

PatentEP3248847B1Webbing take-up device

Publication Date: 2020.05.06 KK TOKAI RIKA DENKI SEISAKUSHO

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AI summary

A webbing take-up controlling device 10 including: a motor 38 that is configured to operate a centrifugal clutch 116; and a controller 102 that controls a voltage applied to the motor 38 such that, in the case of operating the centrifugal clutch 116, a first voltage lower than a target voltage to operate the centrifugal clutch is applied to the motor 38, and then the target voltage is applied to the motor 38.