Motor Vehicle Lock Overload Clutch Cinching Safety
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Solution Overview
Problem
The existing motor vehicle lock cinching function increases user-friendliness but poses an injury risk due to the application of full cinching force when objects or fingers are inserted into the gap between the door and the vehicle body during the closing process, compromising operational safety.
Innovation Solution
Incorporating an overload clutch in the drive train between the cinching drive and the catch, which engages load-dependently in the initial section of the cinching routine and disconnects when a predefined limit load is exceeded, ensuring the pinched object does not withstand excessive force, and transitions to a load-independent engagement in the subsequent section for safe closure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the cinching function is implemented to pull the door from preliminary to main door position, then user-friendliness is improved, but injury risk increases due to full cinching force being applied to objects or fingers in the gap
Solution Approach 1:
The clutch element's engagement state changes dynamically during the cinching routine. Initially engaged to provide overload protection, it disengages when the gap is sufficiently closed to eliminate pinching risk, then re-engages for the final closure. This dynamic behavior allows the system to adapt its force transmission characteristics based on the operational phase, resolving the contradiction between providing full cinching force and preventing injury.
Solution Approach 2:
The system changes the force transmission parameter by transitioning the clutch from an engaged state (limiting force to prevent injury) to a disengaged state (allowing full force for closure). This parameter change enables the cinching function to operate safely in the preliminary phase while maintaining full effectiveness in the final phase, addressing both user-friendliness and safety requirements.
2Object-affected harmful factors
If the overload clutch remains engaged throughout the entire cinching routine to prevent injury, then operational safety is improved, but the cinching force required to close the door seal gap is reduced
Solution Approach 1:
The clutch engagement is made dynamic rather than static. It is engaged during the initial phase when safety is the priority, disengaged during the intermediate phase when full force is needed to overcome seal resistance, and re-engaged for the final phase. This dynamic control allows the system to optimize both safety and force transmission at different stages of the cinching routine.
Solution Approach 2:
The clutch engagement follows a periodic pattern: engaged → disengaged → engaged. This periodic action allows the system to alternately apply force limitation and full force transmission, ensuring safety when needed while maintaining closing capability when the gap is small enough to be safe.
3Object-affected harmful factors
If the gap between door and body is reduced to at least 3 mm during the initial section, then user safety is improved, but additional control complexity is introduced
Solution Approach 1:
The clutch element automatically engages and disengages based on the mechanical conditions in the drive train without requiring external control signals or complex control logic. The disengagement occurs naturally when the gap closure creates sufficient load to overcome the clutch's holding force, and re-engagement occurs when the load decreases. This self-service mechanism achieves safety gap control without adding control system complexity.
Data Source
AI summary
A motor vehicle lock has a pawl and a catch that may be moved into an open position, a preliminary latching position and a main latching position. In one latching position, that catch is or may be brought into holding engagement with a lock striker. During a cinching routine, the catch is moved into its main latching position by a cinching drive. An overload clutch with two clutch elements is provided in the drive train between the cinching drive and the catch. The clutch elements are in engagement with each other for the transmission of cinching forces. The engagement is load dependent in a beginning section of the cinching routine, such that the engagement, and thereby the overload clutch, is disconnected in reaction to exceeding a predefined limit load in the drive train. The engagement is load independent in the remaining, subsequent section of the cinching routine.