Double Pull Latch Mechanism for Vehicle Hood Release
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Solution Overview
Problem
Current vehicle hood latches require two operations to open, one from inside the vehicle and another under the hood, which is inconvenient and does not provide a visual signal for release, and they lack compatibility with active pedestrian protection systems that require greater hood lift during collisions.
Innovation Solution
A latch mechanism with a ratchet and pawl system that allows multiple stage release from inside the vehicle, providing a visual signal for hood release and enhanced pedestrian protection by allowing greater hood lift through a fishmouth mechanism and torsion springs, enabling the striker to move from a primary to a secondary closed position and then to an open position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a traditional two-stage latch mechanism is used, then the hood can be secured reliably, but the user must exit the vehicle to complete the release operation
Solution Approach 1:
The latch mechanism is segmented into two distinct positions: a primary closed position and a secondary closed position. The pawl can engage with either a primary locking surface or a secondary locking surface on the ratchet, creating two separate locked states. This segmentation allows the first pull to transition from primary to secondary position (partial release visible through window), and the second pull to transition from secondary to fully open position, eliminating the need to exit the vehicle.
Solution Approach 2:
The patent adds a dimensional aspect to the latch operation by creating a intermediate secondary closed position between the fully closed and fully open states. This intermediate position provides a visual indicator that the hood is partially released, allowing users to know the hood is secured open without needing to physically inspect it, thus completing the operation from inside the vehicle.
2Loss of information
If a traditional latch mechanism is used, then the structure remains simple, but no visual signal is provided that the hood has been released
Solution Approach 1:
The patent utilizes the visibility of the striker's position relative to the fishmouth opening as a visual indicator. When the striker is in the secondary closed position, it is partially visible through the window, providing a clear visual signal that the hood is partially released. This visual feedback mechanism does not require additional components or complex structures, maintaining simplicity while providing necessary information.
3Object-affected harmful factors
If a standard latch travel is used, then the mechanism fits within normal packaging, but the hood lift is insufficient for active pedestrian protection
Solution Approach 1:
The latch mechanism incorporates a dynamic fishmouth structure that can accommodate extended striker travel. The fishmouth opening is designed to allow the striker to move through a larger range of motion, enabling the hood to lift higher during active pedestrian protection events. This dynamic capability is integrated into the existing latch packaging without requiring significant volume increases, as the fishmouth geometry is optimized to provide the necessary travel within the available space.
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 latch mechanism simplifies hood opening by reducing the need for external lever operation, provides a visual indication of release, and enhances pedestrian safety by allowing greater hood lift during collisions, improving user convenience and safety features.
Implementation Method 1
the ratchet is biased towards the open position for facilitating travel of the striker in a fishmouth of the latch to the secondary closed position
Implementation Method 2
the pawl is biased towards the primary locking position, in the primary closed position the pawl has a pawl locking surface for engaging a primary locking surface on the ratchet
Implementation Method 3
a lift lever biased towards the open position and having a lift surface for moving the striker in the fishmouth away from the secondary closed position and towards the open position
Data Source
AI summary
A latch described herein comprises a ratchet movable between a primary closed position, a secondary closed position and an open position. The ratchet is biased towards the open position for facilitating travel of a striker in a fishmouth of the latch to the secondary closed position. The latch includes a pawl movable between a primary locking position, a secondary locking position and an unlocking position. The pawl is biased towards the primary locking position and has a pawl locking surface for holding the ratchet in the primary closed position and the secondary closed position. The latch includes a lift lever biased towards the open position for moving the striker in the fishmouth away from the secondary closed position and towards the open position when the pawl is in the unlocking position. The striker is further from the primary position when in the open position compared to the secondary closed position.