Vehicle Seatbelt Control System for Reduced Motor Torque

Solution Overview

Problem

Existing seatbelt systems require high torque or large motors to immediately take up seatbelts during minor collisions, leading to increased motor size or current demand, which is inefficient and unnecessary for multiple collision scenarios.

Innovation Solution

A seatbelt system with a take-up device and electronic control unit that delays seatbelt take-up until collision forces decrease below a threshold or a predetermined time has passed, allowing for reduced motor torque and preventing occupant displacement during minor collisions, while activating a pretensioner for major collisions to ensure restraint.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the motor immediately takes up the seatbelt upon collision detection, then the occupant restraint response is rapid, but the motor size and current requirement increase due to high torque demand

Engineering Contradiction:

Improveseatbelt take-up speedVSAvoidmotor size

Core Design Contradiction:

SpeedVSWeight of stationary object

Solution Approach 1:

The system performs preliminary assessment of collision severity before activating the seatbelt take-up mechanism. By detecting collision acceleration and comparing it against thresholds, the system determines whether immediate take-up is necessary or if delayed take-up is sufficient, avoiding unnecessary high-torque motor activation for minor collisions

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system dynamically adjusts the seatbelt take-up timing based on real-time collision detection data. The control unit modifies the take-up strategy according to the detected acceleration magnitude, transitioning between immediate take-up for severe collisions and delayed take-up for minor collisions, optimizing motor torque requirements

Inventive Principle:

Principle #15Dynamics

2Speed

If the motor immediately takes up the seatbelt upon collision detection, then the occupant restraint response is rapid, but the current flowing through the motor increases due to high torque demand

Engineering Contradiction:

Improveseatbelt take-up speedVSAvoidmotor current consumption

Core Design Contradiction:

SpeedVSUse of energy by moving object

Solution Approach 1:

The system performs preliminary assessment of collision severity before activating the seatbelt take-up mechanism. By detecting collision acceleration and comparing it against thresholds, the system determines whether immediate take-up is necessary or if delayed take-up is sufficient, avoiding unnecessary high-current motor activation for minor collisions

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system dynamically adjusts the seatbelt take-up timing based on real-time collision detection data. The control unit modifies the take-up strategy according to the detected acceleration magnitude, transitioning between immediate take-up for severe collisions and delayed take-up for minor collisions, optimizing motor current consumption

Inventive Principle:

Principle #15Dynamics

3Reliability

If the seatbelt is taken up during minor collision, then the occupant displacement is restricted, but the motor requires high torque that increases its size

Engineering Contradiction:

Improveoccupant restraint effectivenessVSAvoidmotor size

Core Design Contradiction:

ReliabilityVSWeight of stationary object

Solution Approach 1:

The system performs preliminary assessment of collision severity before activating the seatbelt take-up mechanism. By detecting collision acceleration and comparing it against thresholds, the system determines whether immediate take-up is necessary or if delayed take-up is sufficient, avoiding unnecessary high-torque motor activation for minor collisions

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system changes the operational parameters of the seatbelt control system based on collision severity. For minor collisions below the threshold, the system uses delayed take-up with lower torque requirements, while for severe collisions above the threshold, it switches to immediate take-up with high torque, optimizing both safety and motor sizing

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS11235722B2Seatbelt system for vehicle, and control method for seatbelt system

Publication Date: 2022.02.01 TOYOTA JIDOSHA KK

AI summary

A seatbelt system includes a take-up device configured to take up a seatbelt, and an electronic control unit configured to, when any one of first and second conditions is satisfied, cause a motor to take up the seatbelt. In the first condition, after occurrence of a collision whose physical quantity detected by a detector configured to detect the physical quantity associated with a magnitude of the collision is less than or equal to a first threshold, the physical quantity decreases to less than or equal to a second threshold. In the second condition, after occurrence of a collision whose physical quantity is less than or equal to the first threshold, a first predetermined time elapses, which is estimated to be equivalent to a decrease in the physical quantity to less than or equal to the second threshold.