Remote Safety Switch Actuation for Elevator Shaft Reactivation
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Solution Overview
Problem
Existing safety switch actuation methods for elevators require direct access to the shaft for reactivation, posing safety risks and being time-consuming, and can result in failure to actuate during emergency braking due to jammed or force-requiring Bowden cables.
Innovation Solution
A remotely operable safety switch actuation device with a plunger, linear drive, return spring, and return actuator that can be externally probed to keep the pushbutton switch actuated and deactivated, eliminating the need for direct access and ensuring actuation during emergency braking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the service technician goes into the elevator shaft to close the safety circuit, then the safety switch can be accessed and closed, but this is time-consuming and dangerous
Solution Approach 1:
A Bowden cable is introduced as an intermediary mechanism that allows the service technician to actuate the safety switch from outside the elevator shaft. The cable transmits the actuating force remotely, eliminating the need for direct access to the switch while maintaining operational capability.
Solution Approach 2:
The actuation mechanism is segmented into separate components: the safety switch remains in its fixed position, while the actuating element is connected via a flexible Bowden cable that can be operated from a remote location. This segmentation allows independent optimization of each component's position and function.
2Ease of operation
If the Bowden cable is used to lift off the element actuating the safety switch, then remote operation is enabled, but the safety switch may not be actuated during emergency braking if the cable is jammed or requires too much force
Solution Approach 1:
The system transitions from a static mechanical connection to a dynamic cable-based connection that can accommodate movement and positioning variations. The Bowden cable provides flexibility in positioning while maintaining the force transmission necessary for actuation, adapting to different operational states.
Solution Approach 2:
The design anticipates potential cable issues by positioning the safety switch and actuating mechanism to ensure sufficient clearance and force margin. The system is configured to maintain reliable actuation even if the cable experiences some resistance or positioning variations, cushioning against potential failure modes.
3Ease of operation
If the Bowden cable has sufficient clearance for operation, then remote actuation is enabled, but this may prevent actuation during emergency braking due to jamming or excessive force requirements
Solution Approach 1:
The system parameters (clearance, force requirements, cable tension) are optimized to balance two opposing needs: sufficient clearance for reliable remote operation and minimal interference during emergency braking. By carefully selecting these parameters, the design ensures that normal operation and emergency response both function reliably without compromising either.
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
Enables safe and efficient reactivation of the safety circuit without direct access to the elevator shaft, preventing actuation failures due to jammed Bowden cables and ensuring reliable operation by using a return spring to maintain the plunger's position until remote deactivation.
Implementation Method 1
the return spring pushes the return actuator to a position more remote from the pushbutton switch. In the process, the return spring takes the plunger with it to its standby position
Data Source
AI summary
An actuation device for keeping the pushbutton switch activated and deactivated remotely. The actuation device includes a plunger which can be brought by external probing from a standby position, in which it does not switch the pushbutton switch, to an active position, in which it keeps the pushbutton switch actuated. The actuation device has a remotely controllable linear drive, a return spring and a return actuator and is designed in such a way that the plunger can be coupled to the return actuator by the remotely controllable linear drive, which is preferably driven by a Bowden cable, under tension of the return spring, wherein after deactivation of the linear drive, the plunger is pressed by the return spring into a position more remote from the pushbutton switch, thereby entraining the plunger into its standby position.