Belt Retractor Locking Control With Dual-Path Signal Transmission
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Solution Overview
Problem
Existing vehicle occupant restraint systems face high costs and latency issues due to separate sensor and drive electronics for each belt retractor, which are not adequately fast for timely belt reel locking during critical vehicle situations.
Innovation Solution
A vehicle occupant restraint system with central sensor electronics generating a locking signal, connected via a separate communication channel directly to drive electronics, utilizing existing bus systems as a fallback, and integrating drive electronics into belt retractors to simplify wiring and meet EMC requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a separate sensor and drive electronics are assigned to each belt retractor, then the locking signal can be transmitted quickly, but the system costs become high
Solution Approach 1:
The sensor electronics are designed to serve multiple functions: they detect vehicle acceleration for airbag deployment, ESP control, and belt retractor locking. This multi-functional approach allows one sensor system to support multiple safety systems, reducing overall system cost while maintaining fast response capabilities through shared hardware resources
Solution Approach 2:
The system separates the communication path into two independent channels: a fast direct wiring connection for critical locking signals and a standard bus system for non-critical data. This segmentation allows the critical path to operate independently without being constrained by bus arbitration delays, achieving fast locking response without requiring separate electronics at each retractor
2Device complexity
If the existing bus system is used for transmitting locking signals, then the system complexity is reduced, but the signal transmission latency increases
Solution Approach 1:
A dedicated direct wiring connection acts as an intermediary communication channel between the sensor electronics and drive electronics for critical locking signals. This separate physical channel bypasses the bus system arbitration mechanism, providing a direct path that eliminates bus-related delays while the bus system continues to handle non-critical communications
Solution Approach 2:
The system prepares multiple communication pathways in advance: the direct wiring connection is pre-configured for immediate signal transmission when locking is required, while the bus system handles routine communications. This preliminary setup ensures that when a critical event occurs, the fast path is already ready without requiring any reconfiguration or arbitration
3Device complexity
If drive electronics are integrated into belt retractors, then wiring complexity is reduced, but electromagnetic compatibility requirements become more stringent
Solution Approach 1:
The drive electronics for the locking system are integrated into the existing drive electronics that control the belt tensioning mechanism. This merging of functions eliminates the need for separate drive electronics at each retractor, simplifying the wiring harness while consolidating electromagnetic emissions into fewer, more manageable locations that can be shielded and filtered more effectively
Data Source
AI summary
The invention suggests a vehicle occupant restraint system (10), comprising central sensor electronics (14) which can generate a locking signal; at least one belt retractor (12) which includes an electromechanical locking system (20); drive electronics (22) which is assigned to and can activate the locking system (20) of the belt retractor (12) in reaction to a locking signal; a bus system (16) to which the sensor electronics (14) and the drive electronics (22) are connected; and a line (18) separate from the bus system (16) which connects the drive electronics (22) to the sensor electronics (14). Further, a method of controlling at least one belt retractor (12) of a vehicle occupant restraint system (10) is suggested in which the following steps are provided:a vehicle acceleration is detected by sensor electronics (14);if the vehicle acceleration exceeds a predetermined threshold, a locking signal is transmitted via a bus system (16) and via a line (18) separate from the bus system (16) to drive electronics (22, 26) which is assigned to an electromechanical locking system of the belt retractor (12),the electromechanical locking system (1) then locks the belt reel.