Motor Vehicle Door Latch Two-Stage Safety Catch
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Motor vehicle door latches produce an acoustically noticeable and discomforting opening sound due to the sudden release of preloading pressure from the sealing gasket when the safety catch disengages from the rotary latch, leading to an abrupt opening motion.
Innovation Solution
The safety catch is moved by the drive element in a two-part movement, first tangentially and then radially, while remaining engaged with the rotary latch, to reduce preloading pressure before disengagement, allowing the hatchback to open smoothly and minimizing the opening sound.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the safety catch is quickly pivoted away from the rotary latch to enable opening, then the opening speed is improved, but the preloading pressure is suddenly released causing an acoustically audible discharge stroke and abrupt opening motion
Solution Approach 1:
The rotary latch is pre-rotated by approximately 15 degrees before the safety catch fully disengages, preparing the closing element for smooth opening movement. This preliminary action ensures that when the safety catch releases, the latch is already positioned to move outward rather than abruptly discharge
Solution Approach 2:
The opening process is divided into two dynamic phases: first, the safety catch pivots away while the rotary latch remains engaged and pre-rotates; second, the safety catch fully disengages and the rotary latch completes its opening motion. This dynamic sequencing controls the release of preloading pressure to minimize acoustic discharge
2Device complexity
If the safety catch is moved in a simple radial path away from the rotary latch, then the device complexity is reduced, but the preloading pressure cannot be reduced before disengagement causing abrupt opening
Solution Approach 1:
The safety catch movement is transformed from a simple radial path to a two-component path: a radial component that moves the catch away from the latch, and a tangential component that enables the rotary latch to pre-rotate. This dimensional change in the movement path allows pressure reduction before disengagement without requiring complex additional mechanisms
3Reliability
If the rotary latch is held firmly engaged with the safety catch during opening, then the locking reliability is improved, but the opening force required increases and opening speed decreases
Solution Approach 1:
The rotary latch is pre-rotated while still engaged with the safety catch, preparing the closing element for opening motion before the actual disengagement occurs. This preliminary rotation reduces the mechanical resistance during the critical disengagement phase, enabling faster opening while maintaining locking reliability during the pre-engagement phase
Data Source
AI summary
A motor vehicle door latch includes a rotary latch which encompasses a closing element when in the closed position, and is preloaded toward an open position of the closing element. A safety catch is engaged with the rotary latch so that the rotary latch is prevented from moving toward the open position. A coupling section of the safety catch is dynamically coupled with a drive element and moves the safety catch between the engagement position and a releasing position so that the rotary latch can move toward the open position. The opening sound is reduced to a minimum. The drive element moves the safety catch from the engagement position toward the releasing position so that the rotary latch, which is still engaged with the safety catch during such movement, moves toward the open position.