Elevator Safety Link with 2:1 Roping Pulley
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing elevator safety devices experience time lag between detecting excessive descending speed and actuating the safety mechanism, leading to potential maximum speed of 1G and delayed stop of the elevator car.
Innovation Solution
A safety link with a 2:1 roping configuration actuation wire and pulley system, where the actuation wire is wrapped 180° around the pulley, allowing twice the movement of the governor rope, thereby reducing activation time and applying a braking force more efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a conventional safety link is used, then the safety device can stop the elevator car, but there is a time lag between detection and actuation causing delayed stoppage
Solution Approach 1:
The patent employs a 2:1 roping configuration where the actuation wire is wrapped around the pulley, creating a mechanical advantage system. When the governor rope moves a certain distance, the pulley rotates and the actuation wire is pulled with twice the movement distance, effectively doubling the actuation speed and reducing response time.
Solution Approach 2:
The pulley acts as an intermediary mechanism between the governor rope and the actuation wire. This intermediary component transforms the linear movement of the governor rope into amplified linear movement of the actuation wire through rotational motion, bridging the time gap between detection and actuation.
2Reliability
If the governor rope is pulled upward to actuate the safety device, then the safety mechanism is activated, but the load on the safety device increases
Solution Approach 1:
The 2:1 roping configuration creates a mechanical advantage where the pulley system distributes and amplifies the force. The actuation wire wrapped around the pulley allows the governor rope to pull with reduced force while achieving the same actuation effect, halving the load on the safety device.
3Speed
If the actuation wire is wrapped around the pulley in a 2:1 configuration, then the response speed is doubled, but the device complexity increases
Solution Approach 1:
The patent uses a simple pulley wheel with the actuation wire wrapped around it in a 2:1 configuration. This straightforward mechanical arrangement doubles the actuation speed without requiring complex mechanisms, maintaining simplicity while achieving the speed improvement.
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 safety link enables faster response to excessive elevator car speeds, reducing the risk of increased speed and potential damage by halving the load on the safety device, allowing for quicker stoppage of the elevator car.
Implementation Method 1
a pulley configured such that the actuation wire is directed upward to the pulley, wrapped around the pulley and then directed downward through the hitch bracket
Implementation Method 2
The safety link is configured such that the movement of the actuation wire is twice as much as the corresponding movement of the governor rope
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A safety link for an elevator car traveling in an elevator hoistway includes a hitch bracket slidably mounted to the elevator car frame so as to be movable in the moving directions of the elevator car and biased toward the downward movement direction of the elevator car in normal operating condition, the hitch bracket connected to the governor rope, and a pulley rotatably mounted to the hitch bracket and including an actuation wire wrapped around the pulley and connected to a safety device.