Elevator Tensioning Sheave Displacement Detection for Hoistway Space Saving
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Solution Overview
Problem
Conventional elevator apparatuses face complexity in speed governor construction when reducing first and second overspeed thresholds near terminal floors, leading to space and cost inefficiencies, and existing solutions fail to effectively shorten buffer dimensions for space saving.
Innovation Solution
Incorporating a tensioning sheave displacement detecting portion that activates a safety device upon downward displacement of the tensioning sheave due to suspending body breakage, allowing for a simpler configuration and reduced buffering stroke, enabling space saving in the hoistway.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the first overspeed Vos and second overspeed Vtr are reduced in the vicinity of terminal floors to shorten buffer stroke, then the buffering stroke can be shortened, but the construction of speed governors becomes complicated
Solution Approach 1:
The patent extracts the detection function from the speed governor by introducing a separate car position switch that detects terminal floor proximity. This allows the speed governor to maintain its original simple construction while the buffer stroke is shortened through the combined action of the position switch and hoisting machine control.
Solution Approach 2:
The patent introduces a car position switch as an intermediary device between the car and the control system. This switch detects when the car is in the vicinity of the terminal floor and provides this information to the controlling apparatus, which then coordinates with the speed governor to achieve reduced buffer stroke without complicating the speed governor itself.
2Speed
If a terminal overspeed Vts detection method using car position switch is used, then the car speed can be controlled near terminal floor, but it is not possible to brake the car using the hoisting machine if the main rope breaks
Solution Approach 1:
The patent applies preliminary action by having the car position switch detect terminal floor proximity in advance and the controlling apparatus prepare for potential emergencies. When the suspending body breaks, the speed governor's second overspeed detection ensures the safety device activates regardless of the main rope status, providing reliable braking capability.
Solution Approach 2:
The patent implements beforehand cushioning through the safety device that is always ready to activate. The buffer is designed with sufficient stroke capacity to handle worst-case scenarios, and the speed governor maintains its full braking capability as a backup even when terminal overspeed control is active.
3Reliability
If the buffer length is determined by the first overspeed Vos and second overspeed Vtr, then the buffer can handle normal overspeed cases, but additional space is required in the hoistway
Solution Approach 1:
The patent applies dynamics by making the effective buffer stroke variable based on car position. When the car is near the terminal floor (detected by the car position switch), the hoisting machine is controlled to limit speed to terminal overspeed Vts, resulting in a shorter effective buffer stroke. When the car is far from the terminal floor, the full buffer stroke capacity is available for handling higher overspeeds Vos and Vtr.
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 effectively shortens the buffering stroke of the buffer, achieving space saving in the hoistway by detecting suspending body breakage through the tensioning sheave displacement detecting portion, simplifying the configuration and enhancing safety device activation reliability.
Implementation Method 1
a tensioning sheave displacement detecting portion that detects downward displacement of the tensioning sheave that accompanies dropping of the car due to breakage of the suspending body
Data Source
AI summary
In an elevator apparatus, a safety device that makes a car perform emergency stopping is mounted to the car. A rope is installed in a loop inside a hoistway. The rope is connected to the car. A tensioning sheave around which the rope is wound is disposed in a lower portion of the hoistway. A tensioning sheave displacement detecting portion detects downward displacement of the tensioning sheave that accompanies dropping of the car due to breakage of the suspending body and activates the safety device.