Vehicle Door Latch with Variable Gear Ratio for Fast Unlock
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Solution Overview
Problem
Existing vehicle door latch systems with passive entry features require multiple motors or large motors to achieve quick unlock, leading to high cost and complexity.
Innovation Solution
A latch assembly with a ratchet and link mechanism, utilizing a transfer assembly with a first gear rotating at a higher speed and lower torque, and a second gear rotating at a lower speed and higher torque, allowing a single small actuator to efficiently move the link and inside lock lever, reducing the need for high torque and complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If multiple motors or large motors are used to achieve quick unlock, then the unlock speed is improved, but the device complexity and cost increase
Solution Approach 1:
The patent applies dynamics by making the gear ratio variable through a shiftable third gear. The third gear can be positioned in different locations along the second shaft to change the effective gear ratio between the first and second gears, allowing the system to optimize between speed and torque dynamically based on operational requirements without needing multiple motors
Solution Approach 2:
The patent changes the parameter of gear ratio by physically repositioning the third gear along the second shaft. This alters the mechanical advantage in the gear train, enabling the single motor to deliver either higher speed or higher torque output as needed for the unlink mechanism or lock lever actuation
2Device complexity
If a single small actuator is used, then the device complexity is reduced, but the torque capability decreases
Solution Approach 1:
The third gear acts as an intermediary element that can be shifted to different positions on the second shaft. This intermediary gear modifies the torque transmission path, allowing a single small motor to achieve both high-speed low-torque operation for the unlink and high-torque operation for the lock lever by changing the effective gear ratio
Solution Approach 2:
The dynamic repositioning of the third gear creates a variable transmission system where the same motor can deliver different torque levels to different outputs (unlink or lock lever) based on the instantaneous position of the third gear, eliminating the need for multiple actuators with different torque capabilities
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 solution enables quick door opening with reduced motor torque requirements, simplifying the design and lowering manufacturing costs while maintaining efficient operation.
Implementation Method 1
The transfer assembly includes a first gear that is rotatable, has a first radius and is connected to the link for providing the movement of the link. The transfer assembly also includes a second gear that is rotatable, has a second radius and is connected to the inside lock lever for providing the movement of the inside lock lever. The second radius of the second gear is larger than the first radius of the first gear for rotating the first gear at a higher speed and with lower torque than the second gear to quickly move the link, and for rotating the second gear at a lower speed and with higher torque than the first gear to forcefully move the inside lock lever.
Implementation Method 2
The second radius of the second gear is larger than the first radius of the first gear for rotating the first gear at a higher speed and with lower torque than the second gear to quickly move the link, and for rotating the second gear at a lower speed and with higher torque than the first gear to forcefully move the inside lock lever.
Implementation Method 3
a ratchet that is moveable between a closed position in which the striker is retained within the latch and an open position in which the ratchet releases the striker from the ratchet
Data Source
AI summary
A closure latch assembly for a vehicle door comprising a lock link operatively connected to a ratchet is provided. The latch assembly is configured to quickly move the lock link to an unlocking position and thus the ratchet to an open position when a user activates a motor of the latch assembly, for example using a key fob. Thus, an impatient passenger can quickly open the door, even while other components of the latch assembly are still moving toward their respective unlocking positions.