Emergency Lock Actuator with SMA Blocking Mechanism
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electric vehicle locks face challenges in emergency conditions post-accident, where increased friction forces render traditional electric motors and Shape Memory Alloy (SMA) actuators inadequate for opening the lock, as they either fail to generate sufficient force or have excessive thermal inertia, leading to unreliable operation.
Innovation Solution
A lock design incorporating a high-diameter SMA actuator with a blocking mechanism, such as a detent, that applies forces exceeding 100 N, specifically for emergency conditions, while a conventional actuator handles normal operations, and includes features to prevent accidental activation from external thermal conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If a high-diameter SMA actuator is used to generate sufficient force for emergency conditions, then the force capability is improved, but the thermal inertia increases leading to slower response time
Solution Approach 1:
The actuation system is segmented into two distinct actuators: a conventional electric motor for normal operations and a high-diameter SMA actuator for emergency conditions. This segmentation allows each actuator to be optimized for its specific function without compromise - the SMA actuator can be sized for maximum force without worrying about response time during normal use, while the conventional motor handles routine operations.
Solution Approach 2:
The system dynamically switches between two actuation modes based on operational conditions. The blocking mechanism (detent) remains engaged during normal operation, preventing the high-force SMA actuator from activating. In emergency conditions, the blocking mechanism releases, allowing the SMA actuator to engage and provide the necessary high force for door release.
2Loss of time
If a conventional electric motor is used for normal operations, then the response time is improved, but the force capability is insufficient for emergency conditions
Solution Approach 1:
The actuation system is segmented into two distinct actuators: a conventional electric motor for normal operations and a high-diameter SMA actuator for emergency conditions. This segmentation allows each actuator to be optimized for its specific function without compromise - the SMA actuator can be sized for maximum force without worrying about response time during normal use, while the conventional motor handles routine operations.
Solution Approach 2:
The system dynamically switches between two actuation modes based on operational conditions. The blocking mechanism (detent) remains engaged during normal operation, preventing the high-force SMA actuator from activating. In emergency conditions, the blocking mechanism releases, allowing the SMA actuator to engage and provide the necessary high force for door release.
3Ease of operation
If the blocking mechanism is designed to release at lower force thresholds, then the ease of operation is improved, but the reliability in emergency conditions deteriorates
Solution Approach 1:
The blocking mechanism is designed with specific mechanical parameters (detent depth, spring force, engagement geometry) that create a high force threshold for release. This parameter configuration ensures that only forces exceeding normal operational ranges - such as those generated by the high-diameter SMA actuator in emergency conditions - can release the detent, preventing accidental activation while ensuring reliable emergency operation.
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 ensures reliable operation under both normal and emergency conditions by providing a high-force SMA actuator for emergency situations and a conventional actuator for everyday use, with safety features to prevent accidental opening, addressing the limitations of previous SMA actuator designs.
Implementation Method 1
the shape memory phenomenon consists in the fact that a mechanical piece made of an alloy that exhibits said phenomenon is capable of transitioning, upon a temperature change, between two shapes that are preset at the time of manufacturing of the mechanical piece
Implementation Method 2
This occurs thanks to the transformation of the micro-crystalline structure of the piece that passes from a type called martensitic (M), stable at lower temperatures, to a type called austenitic (A), stable at higher temperatures, and vice versa (M/A and A/M transition)
Implementation Method 3
In the M/A transition the wire undergoes a shortening
Implementation Method 4
the temperature of the SMA actuator can be easily and repeatedly increased by Joule effect, supplying a current to the SMA wire
Data Source
AI summary
A lock for closing a door with respect to a frame. The lock includes a lock body mounted on the door and a striker mounted on the frame, or vice versa. The lock body includes a catch element mounted so as to rotate between a striker keep position and a striker release position; elastic means suitable for driving the catch element from the striker keep position to the striker release position; a lever suitable for moving between two positions, a closing position in which it maintains the catch element in the striker keep position and an opening position in which it is disengaged from the catch element; and a service actuator suitable for applying a force f on the lever so as to bring it from the closing position to the opening position. The lock body further includes an emergency SMA actuator suitable for applying a force on the lever so as to bring it from the closing position to the opening position. The SMA actuator can apply a force higher than 100 N and including blocking means for allowing the force to be applied on the lever only when the force exceeds a predetermined threshold value.