Vehicle Latch Release Actuator With Worm Wheel Cam Lobes
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Solution Overview
Problem
Current vehicle latch systems face challenges in compact design and low mass production while maintaining performance under various conditions, particularly with rear door latches that experience excessive inertia, leading to increased packaging concerns and higher release efforts due to extended pawl release levers and additional components like memory levers, which also generate unwanted noise.
Innovation Solution
A vehicle latch system featuring a pawl and claw mechanism with a worm wheel having cam lobes in distinct planes, a spring-biased release lever, and a motor assembly, where the center of gravity of the pawl and release lever work together to provide robustness against external acceleration, allowing for a smaller return spring and reduced energy requirements, and integrating a memory lever into the housing to minimize additional components and noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If an extended pawl release lever is used to transfer the center of gravity of the pawl, then the opening torque is increased, but the packaging area increases and release effort increases
Solution Approach 1:
The patent introduces a memory lever that operates in a different dimensional plane from the pawl and release lever. The memory lever rotates about a different axis and interacts with the release lever through a cam mechanism, allowing the system to achieve enhanced torque control without extending the pawl release lever in its original plane, thus avoiding increased packaging area.
Solution Approach 2:
The memory lever acts as an intermediary component between the release actuator and the pawl mechanism. It receives rotational input from the release actuator and transforms it into the appropriate torque on the pawl through the cam mechanism, enabling controlled release effort without requiring an extended pawl release lever.
2Reliability
If a larger pawl return spring is implemented to counteract inertia events, then the release effort is increased, but the packaging area increases
Solution Approach 1:
The memory lever provides an additional degree of freedom that allows the system to manage inertia forces in a different dimensional space. By rotating the memory lever about a different axis and using the cam mechanism to control the release lever, the system can resist inertia events without requiring a proportionally larger pawl return spring, thus avoiding increased packaging area.
Solution Approach 2:
The cam mechanism on the memory lever changes the mechanical parameters of the release system dynamically. As the cam rotates, it modifies the force transmission characteristics between the release actuator and the pawl, allowing the system to handle inertia events with appropriate spring size without requiring excessive packaging area.
3Force
If an extended pawl release lever with higher torque return spring is used, then the release effort is increased, but the energy consumption increases
Solution Approach 1:
The memory lever serves as an intermediary that optimizes the energy transmission path. It uses the cam mechanism to provide mechanical advantage, allowing the release actuator to generate the necessary release effort with reduced energy consumption compared to directly using an extended pawl release lever with a high-torque spring.
Solution Approach 2:
The cam mechanism dynamically changes the force and displacement parameters during the release cycle. By optimizing the cam profile and the interaction between the memory lever and release lever, the system achieves the required release effort with minimized energy consumption from the actuator.
4Reliability
If additional components like memory lever and return spring are added, then the device complexity increases, but the sound generation increases
Solution Approach 1:
The memory lever is integrated into the existing latch housing structure, merging the memory lever function with the housing rather than adding it as a separate external component. This integration reduces the overall device complexity and minimizes the sources of sound generation while maintaining the necessary functionality.
Solution Approach 2:
The cam mechanism on the memory lever acts as an intermediary that smooths the force transmission and reduces impulsive loads that cause noise. By gradually engaging and disengaging the cam surfaces, the system reduces sudden force changes that would otherwise generate unwanted sound from the additional components.
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 results in a more robust and efficient latch system with reduced package size, lower energy requirements for release, and improved sound performance by minimizing spring torque and eliminating the need for a larger return spring, enhancing crashworthiness and manufacturing ease.
Implementation Method 1
the release lever may be spring biased into a rest position by a spring
Implementation Method 2
a worm wheel having a plurality of cam lobes, wherein each of the cam lobes are located in separate and distinct planes with respect to each other
Data Source
AI summary
A vehicle latch having: a frame; a pawl rotatably mounted to the frame for movement between an engaged position and a disengaged position; a claw rotatably mounted to the frame for movement between a latched position and an open position, wherein pawl is configured to impede rotational movement of the claw from the latched position to the open position when the pawl is in the engaged position; a release lever rotatably mounted to the frame; and a worm wheel having a plurality of cam lobes, wherein each of the cam lobes are located in separate and distinct planes with respect to each other, wherein the release lever operably couples the pawl to the worm wheel such that rotational movement of the worm wheel rotates the pawl.