Elevator Speed Governor Triggering Arm Design
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Solution Overview
Problem
In low-speed elevators, the existing speed governor assemblies often trigger falsely due to a small difference between the first and basic running speeds, leading to potential damage and non-compliance with national safety standards, as the overspeed protection switch may not be triggered in time or at all.
Innovation Solution
The speed governor assembly is designed such that the centrifugal mechanism deploys to trigger the overspeed protection switch at a first speed, with a ratio of first to second speed set between 0.9-1.0, ensuring the electrical brake is triggered before the mechanical brake, and includes a triggering arm to guarantee timely activation of the overspeed protection switch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the overspeed protection switch is set farther away to increase the first speed, then the difference between the first speed and basic running speed increases (reducing false triggering), but the overspeed protection switch may not be triggered in time or at all before the mechanical brake device
Solution Approach 1:
The speed governor assembly is divided into two independent triggering paths: one for the overspeed protection switch (electrical brake) and one for the mechanical brake device. Each path has its own adjustment mechanism, allowing the first speed threshold to be set higher than the second speed threshold, ensuring the electrical brake triggers first without compromising either timing or reliability
Solution Approach 2:
The patent changes the speed threshold parameters by allowing the first speed to be greater than the second speed (ratio > 1), which is the reverse of conventional designs. This parameter inversion resolves the contradiction by enabling the overspeed protection switch to be positioned farther away (reducing false triggering) while still ensuring timely activation before the mechanical brake engages
2Reliability
If the ratio of first speed to second speed is kept below 0.9 to meet national standards, then safety compliance is achieved, but in low-speed elevators the first speed is too close to the basic running speed causing false triggering
Solution Approach 1:
The patent inverts the conventional speed ratio relationship by setting the first speed greater than the second speed (ratio > 1), opposite to traditional designs where the first speed is lower. This inversion allows the electrical brake to trigger after the mechanical brake threshold but still before actual overspeed damage occurs, eliminating false triggering in low-speed elevators while maintaining safety compliance
Solution Approach 2:
The mechanical brake device is configured to engage at a lower speed threshold (second speed) as a preliminary protective action, while the electrical brake (overspeed protection switch) is set to trigger at a higher speed (first speed). This preliminary action ensures that even if the electrical brake threshold is raised to avoid false triggering, the mechanical brake provides early protection
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
This configuration ensures the electrical brake is activated before the mechanical brake, reducing false triggering and meeting national safety standards by allowing the overspeed protection switch to be set farther, thereby increasing the difference between the first and basic running speeds.
Implementation Method 1
a centrifugal mechanism (4) mounted on the sheave and rotated together with the sheave; an overspeed protection switch (20) disposed at a first distance from a radial outer side of the centrifugal mechanism (4)
Data Source
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AI summary
The present invention provides a speed governor assembly and an elevator system. The speed governor assembly includes: a sheave (3); a centrifugal mechanism (4) mounted on the sheave and rotating together with the sheave; an overspeed protection switch (20) at a first distance from a radial outer side of the centrifugal mechanism; a core ring (5) disposed coaxially with the sheave; and a triggering arm (7) rotating together with the core ring; wherein the centrifugal mechanism engages with the core ring and drives the core ring and the triggering arm to rotate when the sheave reaches a second speed, and the rotation of the triggering arm can contact and trigger the overspeed protection switch. The speed governor assembly and the elevator system according to the present invention ensure that the electrical brake device of the elevator system is triggered not later than the mechanical brake device and eliminate the possibility that electrical action speed of the speed governor assembly does not meet the requirements of the relevant national standards.