Hold-Open Latch Lever to Prevent Pawl Re-Engagement
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Solution Overview
Problem
Existing vehicle latches often fail to maintain the pawl in a released position after unlatching, leading to unintended re-engagement with the claw, especially during slamming events, which prevents the panel from opening as intended.
Innovation Solution
A latch design incorporating a hold open lever and gear mechanism, actuated by a motor-driven worm, ensures the pawl remains disengaged until the panel is manually opened, using springs and a cam portion to prevent re-engagement with the claw during slamming events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a remote unlatch mechanism is used to release the pawl from the claw, then the panel can be opened remotely, but the pawl may re-engage the claw before the panel opens, causing the opening to fail
Solution Approach 1:
The hold open lever is positioned in advance to block the pawl's re-engagement path with the claw. When the unlatch mechanism activates, the hold open lever is already in place to prevent the pawl from returning to the engaged position, ensuring the panel remains open even if the unlatch signal is de-energized before opening occurs.
2Speed
If the claw rotates at high speed during a slam event, then the latch can respond to closing forces, but the pawl is pushed back with excessive energy, preventing proper engagement
Solution Approach 1:
The hold open lever acts as an intermediary element between the pawl and the claw's motion during slam events. By positioning the hold open lever to engage the pawl, it mediates the energy transfer and controls the pawl's movement, preventing the excessive displacement that would occur from direct high-speed claw rotation and ensuring reliable engagement.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The design effectively maintains the pawl in a disengaged state, allowing the panel to open as intended, even under forces like ice buildup or slamming, by insulating the hold open function from slamming energy.
Implementation Method 1
a spring for biasing the hold open lever into the second position as the gear is rotated into the second position
Implementation Method 2
the gear having a cam portion that is configured to engage the pawl and move the pawl to the disengaged position as the gear rotates from the first position to the second position
Data Source
AI summary
A latch, including: a claw movably mounted to the latch for movement between an unlatched position and a latched position; a pawl movably mounted to the latch for movement between an engaged position and a disengaged position, wherein the pawl prevents the claw from moving from the latched position to the unlatched position when the pawl is in the engaged position; a hold open lever configured for movement between a first position wherein the hold open lever does not block movement of the pawl and a second position, wherein the hold open lever prevents the pawl from moving from the disengaged position to the engaged position; a gear rotatably mounted to the latch for movement between a first position and a second position, the gear having a cam portion that is configured to engage the pawl and move the pawl to the disengaged position as the gear rotates from the first position to the second position; and a spring for biasing the hold open lever into the second position as the gear is rotated into the second position, the spring being operably coupled to the pawl at one end and the hold open lever at a second end.