Elevator Car Speed Control for Short Buffer Stroke
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Solution Overview
Problem
Conventional elevator devices require longer buffers and deeper pit spaces to accommodate higher speeds, leading to increased space occupation and reduced operational efficiency due to limited speed at terminal ends, which affects convenience and efficiency.
Innovation Solution
An elevator system with a car and counterweight that can operate at variable speeds and accelerations, featuring a car buffer, weight buffer, and emergency terminal speed-limiting means to prevent overspeed, allowing for shorter buffers and flexible speed control without increasing space requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the highest speed of the car is increased to improve operational efficiency, then the buffer stroke must be increased and the pit depth must be increased, which increases the space occupied by the elevator device
Solution Approach 1:
The patent applies dynamics by making the speed limit position variable rather than fixed. The speed limit position is dynamically adjusted based on the buffer stroke length, allowing the system to adapt its operational characteristics to different buffer configurations. This enables high-speed operation when using long-stroke buffers while permitting shorter buffers to be used with appropriately adjusted speed limit positions, thereby resolving the contradiction between operational efficiency and space occupation.
2Length of stationary object
If forced speed reduction means is used to limit the highest speed near terminal ends to allow shorter buffers, then the operational efficiency and convenience are reduced
Solution Approach 1:
The patent applies local quality by implementing speed limitation only in specific local regions (near terminal ends) rather than throughout the entire shaft. The speed limit position is set at a distance from the terminal end that corresponds to the buffer stroke length, creating a localized control zone. This allows the car to operate at high speeds in the majority of the shaft while applying speed reduction only where necessary to protect the buffers, thereby maintaining operational efficiency while enabling shorter buffers.
3Productivity
If the highest speed at terminal end section is not limited to maintain operational efficiency, then a long buffer with long buffer stroke is required, which increases pit depth and space occupation
Solution Approach 1:
The patent applies preliminary action by implementing speed reduction before the car reaches the terminal end section. The speed limit position is positioned at a distance from the terminal end that allows the car to decelerate in advance, ensuring that the car arrives at the terminal end at a safe speed compatible with the buffer stroke length. This preliminary speed control enables the use of shorter buffers while maintaining high-speed operation for most of the journey, resolving the contradiction between operational efficiency and buffer stroke length.
Data Source
AI summary
An elevator device includes: a controller and an emergency terminal speed-limiting device to decelerate a car when speed of the car within a predetermined certain distance from an terminal end section of a shaft is detected to have reached or exceeded an overspeed reference. The overspeed reference is set smaller as a distance of the car from the terminal end section of the shaft decreases. The controller includes: a lower deceleration limit determination controller to determine a lower deceleration limit at which the speed of the car is caused to be at or below the overspeed reference, based on a position and a speed of the car within the certain distance from the terminal end section of the shaft, and a deceleration controller to control deceleration of the car within the certain distance, in a range greater than the lower deceleration limit determined by the lower deceleration limit determination unit.