Worm Drive Locking Device Resolving Preload and Complexity
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Solution Overview
Problem
Electromechanical drop-bolts often fail to retract due to 'preload' conditions, such as sideways pressure or air pressure differences, leading to locking device failure and complexity in construction with many moving parts, which increases manufacturing costs and vulnerability to tampering.
Innovation Solution
A rotary motor-driven worm drive mechanism with a pivotally mounted bolt, return spring, and microswitches that resist forces parallel to the gear's axis of rotation, ensuring the bolt can be reliably extended and retracted, and an onboard power storage system for fail-safe operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a roller nut and screw shaft mechanism is used to overcome preload, then the bolt can be rotated to extended position, but the device complexity increases and manufacturing cost increases
Solution Approach 1:
The invention extracts and eliminates the roller nut and screw shaft components from the system, replacing them with a direct motor-to-gear connection. This removal of unnecessary components reduces the number of moving parts while maintaining the bolt extension function through a simplified direct-drive mechanism.
Solution Approach 2:
Instead of using a complex roller nut-screw shaft mechanism to achieve bolt rotation, the invention inverts the approach by using a simple geared motor system where the motor directly drives the bolt through gears. This inversion simplifies the mechanical transmission path while achieving the same functional outcome.
2Reliability
If more moving parts are added to overcome preload, then the locking function can be improved, but the vulnerability to tampering increases
Solution Approach 1:
The invention removes multiple moving parts that create vulnerability points for tampering. By extracting the roller nut, screw shaft, and other intermediate components, the system achieves its locking function with fewer exposure points that intruders could potentially exploit.
Solution Approach 2:
The invention changes the fundamental parameter of mechanical transmission from a multi-component system to a direct-drive geared system. This parameter change reduces the number of interfaces and moving parts that could be targeted for tampering while maintaining secure locking functionality.
3Force
If a complex mechanism with many parts is used, then preload resistance can be improved, but the manufacturing cost increases
Solution Approach 1:
The invention extracts the complex roller nut and screw shaft assembly and replaces it with a simple geared motor system. This extraction eliminates the need for precision-machined threaded components and complex assemblies, significantly reducing manufacturing complexity and cost while maintaining adequate preload resistance through the direct-drive mechanism.
Solution Approach 2:
Instead of building up complexity with multiple components to achieve preload resistance, the invention inverts the approach by using a simplified direct-drive system. The motor's inherent torque characteristics combined with the gear reduction provide sufficient force to overcome preload conditions without requiring complex mechanical assemblies.
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 provides a simplified locking device with improved preload resistance, tolerance for door misalignment, and reliable fail-safe operation, reducing manufacturing costs and enhancing security by minimizing moving parts and ensuring the lock remains secure even without continuous power.
Implementation Method 1
a return spring for moving the bolt from the extended to the retracted position
Implementation Method 2
a worm drive arrangement including a worm and a gear; and a pivotally mounted bolt which is rotatable between a retracted position and an extended position
Data Source
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AI summary
A locking device is described including: a rotary motor; a worm drive arrangement including a worm and a gear; and a pivotally mounted bolt which is rotatable between a retracted position and an extended position; the motor is arranged to drive the worm to rotate the gear; as the gear rotates it cooperates with a cam formation associated with the bolt to move the bolt between the retracted and extended positions.