Vehicle Door Latch Memory Lever Prevents Pawl Obstruction
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Solution Overview
Problem
Vehicle door latches often malfunction due to decreased door seal force over time or in cold weather, causing the pawl to obstruct the ratchet, requiring a second pull on the door handle for opening.
Innovation Solution
A vehicle latch system incorporating a ratchet, pawl, memory lever, and release lever, where the memory lever prevents the pawl from obstructing the ratchet during delays between door handle pull and door opening, allowing for a delay between handle activation and door opening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the door seal force decreases due to aging or cold weather, then the door seal's ability to assist in pulling the striker from the ratchet deteriorates, but the basic latching function must be maintained
Solution Approach 1:
The memory lever is positioned to preemptively block the pawl's movement path before the pawl can engage and lock the ratchet. This preliminary blocking action prevents the pawl from obstructing the ratchet's release, compensating for the insufficient door seal force that would otherwise fail to pull the striker from the ratchet during delayed door opening operations
2Loss of time
If there is a delay between pulling the door handle and opening the door, then the pawl can inadvertently move to obstruct the ratchet release, but the door should remain openable after delay
Solution Approach 1:
The memory lever is pre-positioned to intercept and block the pawl's movement before the pawl can complete its engagement with the ratchet. This preliminary blocking ensures that even during delayed door opening operations, the pawl cannot obstruct the ratchet's release, maintaining reliable latch release after time delays
Solution Approach 2:
The memory lever acts as an intermediary component between the pawl and the ratchet. By positioning itself in the pawl's movement path, the memory lever mediates the interaction between these two components, preventing direct pawl-ratchet engagement that would cause obstruction during delayed door opening operations
3Ease of operation
If a second pull on the door handle is required to open the door, then the door can be opened despite pawl obstruction, but the ease of operation deteriorates
Solution Approach 1:
The memory lever preemptively blocks the pawl's engagement path, preventing the pawl from obstructing the ratchet release in the first place. This eliminates the need for a second door handle pull, reducing the time and effort required for door opening operations
Data Source
AI summary
A closure latch for a vehicle door is provided. The closure latch includes an emergency lock actuator to permit a person to lock the door in the event that the power lock actuator is unusable. The latch also includes an ‘impatient passenger’ feature, which permits the doors to be unlocked using the remote keyless-entry feature on the key fob even in a situation where an ‘impatient passenger’ had prematurely lifted the door handle of the vehicle. In some prior art latches, such an action by an ‘impatient passenger’ would prevent the drive motor on the latch from unlocking the latch, thereby necessitating the owner to press the unlock button on the key fob a second time. There is some overlap in the components that used for the ‘impatient passenger’ feature and the components used for the emergency lock actuator, thereby reducing cost and complexity of the latch.