Electric Belt Retractor Control for Blocking Catch Engagement
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Solution Overview
Problem
The existing electric belt retractor systems cause unnecessary stress and discomfort to vehicle occupants by applying additional belt force during the unlocking process, as the blocking catch is released regardless of whether it is engaged in the blocking teeth, due to the lack of state monitoring.
Innovation Solution
Implement a method where the electric motor is operated in the belt retraction direction only when belt withdrawal is detected, ensuring the blocking catch is drawn into the blocking teeth, and the unlocking operation is adapted to the extent of belt withdrawal, with a quantitative determination of belt band movement to minimize unnecessary force increase.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electric motor is operated to unlock the blocking catch regardless of its state, then the blocking catch can be released from blocking teeth, but unnecessary belt force increases and occupant discomfort occur
Solution Approach 1:
The control unit monitors the state of the blocking catch through sensor signals and uses this feedback information to determine whether unlocking operation is necessary. The control unit only activates the electric motor for unlocking when the blocking catch is actually engaged in the blocking teeth, as indicated by the sensor signal, thereby avoiding unnecessary belt force increases.
Solution Approach 2:
The system uses the existing sensor that monitors blocking catch state for the dual purpose of both accident detection and unlocking control. The blocking catch state information, already available for safety assessment, is reused to control the unlocking operation, eliminating the need for additional monitoring components.
2Reliability
If the blocking catch is drawn into blocking teeth during tensioning, then reliable blocking is achieved, but subsequent unlocking operation causes additional belt band retraction
Solution Approach 1:
The control unit receives sensor signals indicating whether the blocking catch is engaged in the blocking teeth and uses this feedback to conditionally activate the unlocking operation. Only when engagement is detected does the control unit command the electric motor to perform unlocking, thereby avoiding unnecessary belt band retraction and improving occupant comfort.
Solution Approach 2:
Instead of performing a complete unlocking operation regardless of state, the system applies partial action by only executing unlocking when actually needed. The electric motor is activated for a brief period sufficient to release the blocking catch from engagement, minimizing unnecessary belt band retraction while ensuring reliable unlocking when required.
Data Source
AI summary
A method for controlling an electric belt retractor (16) which has an electric motor (20) which can drive a belt spool (18) in a belt band retraction direction and/or in a belt band withdrawal direction, and a blocking catch which is able to be guided into blocking teeth in order to block a rotation of the belt spool (18) in the belt band withdrawal direction, comprises the following steps:Operating the electric motor (20) in belt band retraction direction for tensioning the belt band (26);Detecting a possible belt band withdrawal;Determining a stable vehicle state; andRe-operating the electric motor (20) in belt band retraction direction only when a belt band withdrawal is detected.