Overspeed Protection Switch Self-Reset Mechanism
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Solution Overview
Problem
Existing overspeed governor assemblies for elevators lack a reliable self-reset mechanism for the overspeed protection switch, making it difficult to return to a safe operational state after a speed-related brake engagement, which is essential for repeated use.
Innovation Solution
An overspeed protection switch with a self-reset function, comprising a trigger member, protrusions, a reset lever, and an actuation device, which allows the trigger member to toggle between triggered and untriggered positions, enabling automatic return to the untriggered state upon receiving a reset command, facilitated by a link mechanism and actuator.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an overspeed protection switch is implemented in the governor assembly, then safety protection is provided when overspeed occurs, but the switch cannot be returned to the untriggered position after tripping, preventing repeated use
Solution Approach 1:
The reset lever is designed to automatically engage with the protrusion on the trigger member when the elevator car is stationary, using gravity and the mechanical configuration to self-reset the switch without requiring external intervention. This self-service mechanism resolves the contradiction by enabling automatic return to the untriggered position while maintaining safety protection functionality.
Solution Approach 2:
The trigger member is designed with rotational freedom around its longitudinal axis, allowing it to dynamically transition between triggered and untriggered positions. The reset lever provides a mechanical pathway that enables this dynamic movement, resolving the contradiction between maintaining a stable triggered state for safety and enabling dynamic resetting for operational continuity.
2Ease of operation
If a complex reset mechanism is added to enable self-reset function, then the switch can be returned to untriggered position, but the device complexity increases
Solution Approach 1:
The reset lever is integrated into the existing governor assembly structure, combining the reset function with the overall mechanical configuration. Rather than adding a separate complex reset system, the design merges the reset capability into the existing trigger member and lever arrangement, reducing overall device complexity while achieving the self-reset function.
Solution Approach 2:
The protrusion on the trigger member serves as an intermediary element that transfers the resetting action from the reset lever to the trigger member's rotational position. This simple intermediary mechanism enables the self-reset function without requiring complex transmission systems, maintaining device simplicity while achieving operational ease.
3Adaptability or versatility
If the trigger member is designed to rotate in both directions, then it can adapt to different rotational directions of the centrifugal mechanism, but the structure becomes more complex
Solution Approach 1:
The trigger member is designed with universal rotational capability around its longitudinal axis, allowing it to respond to centrifugal mechanism rotation in either direction. This multi-functional design enables the same component to handle both clockwise and counter-clockwise rotation scenarios without requiring direction-specific mechanisms, achieving adaptability without proportionally increasing complexity.
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 simple, cost-effective, and efficient mechanism for the overspeed governor assembly to reset the protection switch, ensuring the elevator can operate safely after maintenance, reducing the thrust requirement for the actuation device and maintaining low operational costs.
Implementation Method 1
When the rope sheave exceeds a predetermined speed, a centrifugal mechanism toggles a trigger member
Implementation Method 2
an actuator having an action end capable of performing a linear reciprocating movement; a link mechanism, via which the actuator is connected to a pivot shaft; and the pivot shaft connected to the reset lever, wherein the pivot shaft rotates when driven by the actuator
Data Source
AI summary
An overspeed protection switch, an overspeed governor assembly and an elevator system are provided. The overspeed protection switch includes: a trigger member, which is in an untriggered position when the overspeed governor assembly is in normal operation, and which is capable of rotating to a triggered position from the untriggered position when being toggled by a centrifugal mechanism of the overspeed governor assembly in case of overspeed of the overspeed governor assembly; at least one protrusion connected to the trigger member and rotating together with the trigger member; a reset lever which is rotatable along an axial axis from an idle position to act on one of the at least one protrusion to drive the trigger member to return to the untriggered position from the triggered position; and an actuation device which, in response to a reset command, acts on the reset lever to rotate the reset lever.