Master Ratchet and Slave Catch Linkage for B-Pillarless Vehicle Latches
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Solution Overview
Problem
In vehicles without a B-pillar, the roof tends to buckle during a frontal crash, exerting excessive loads on the latch and potentially causing undesirable unlatching, as current door systems lack sufficient support and kinematic compatibility for catcher pins.
Innovation Solution
A latching system featuring a master ratchet and slave catch mechanism, connected via a linkage, which moves in tandem to securely engage and disengage the striker and secondary striker, enhancing safety and stability by providing additional support during crashes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a typical latch system is used in vehicles without a B-pillar, then the door system meets regulatory requirements and provides comfort, but the roof buckles during frontal crash exerting excessive loads on the latch causing undesirable unlatching
Solution Approach 1:
The latch system is divided into two independent but coordinated latching mechanisms: a primary latch with ratchet and striker, and a secondary latch with catch and secondary striker. This segmentation allows each latch to independently handle crash loads, preventing single-point failure and maintaining door security during roof buckling events
Solution Approach 2:
The patent modifies the latching system by adding a secondary latch mechanism that changes the overall structural parameter of the door retention system. This dual-latch configuration increases the force distribution and structural redundancy, enabling the system to withstand excessive loads from roof buckling without unlatching
2Reliability
If catcher pins are added to account for roof buckling, then latch security during crash is improved, but the latch packaging does not allow enough room for these pins and the kinematics of door swing may not allow the catcher pins to work as desired
Solution Approach 1:
The secondary latch mechanism is integrated into the existing latch housing and actuation system. The catch is mounted within the same housing as the ratchet, and both are actuated through a unified linkage system, merging the secondary safety function into the primary latch structure without requiring separate packaging space
Solution Approach 2:
The linkage system serves multiple functions: it actuates both the primary ratchet and secondary catch simultaneously, provides mechanical advantage for both latching operations, and coordinates the kinematics of door swing for both mechanisms. This multi-functionality eliminates the need for separate actuation systems that would increase packaging complexity
3Reliability
If a master ratchet and slave catch mechanism with linkage is used, then latch security during crash is enhanced, but the device complexity increases
Solution Approach 1:
The linkage connecting the ratchet and catch is designed to move dynamically with the door swing kinematics. The linkage automatically adjusts the actuation forces and timing based on the door position and crash load conditions, providing adaptive latching that maintains simplicity while enhancing security
Solution Approach 2:
The dual-latch system is designed to be self-actuating through the unified linkage mechanism. When the door closes, the striker and secondary striker automatically engage the ratchet and catch respectively. During crash conditions, the mechanical advantage of the linkage automatically increases the latching forces without requiring additional active control systems
Data Source
AI summary
A latch for a closure panel of a vehicle, the latch comprising: a housing; a ratchet mounted to the housing for releasably securing a striker in a slot; a catch mounted to the housing for releasably securing a secondary striker; and a linkage connecting the catch to the ratchet; wherein the ratchet and the catch move in tandem with one another via the linkage.