Elevator Overspeed Detection for Shock Absorber Sizing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional elevator systems face challenges in reducing hoistway size due to the need for a larger shock absorber to accommodate varying collision speeds, as the first and second overspeed detection levels are based on the car's running speed pattern, leading to inconsistent collision speeds with the shock absorber.
Innovation Solution
An elevator apparatus with a safety device that sets overspeed detection levels based on the car's position, activating the braking device to ensure the car reaches the shock absorber at a predetermined speed, allowing for a smaller shock absorber and reduced hoistway size by controlling the car's speed through the hoisting machine brake and emergency stop devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the first and second overspeed detection levels are set based on the car's running speed pattern, then the brake and emergency stop device can be actuated to prevent excessive speed, but the collision speed with the shock absorber varies and requires a larger shock absorber size
Solution Approach 1:
The patent applies dynamics by making the overspeed detection level variable rather than fixed. The detection level changes dynamically based on the car's position in the hoistway, allowing the system to optimize braking timing and collision speed control. This dynamic adjustment enables the shock absorber to be sized for a specific target collision speed rather than accommodating the full range of possible collision speeds, thereby reducing its size.
Solution Approach 2:
The patent changes the parameter of overspeed detection level from a static value to a variable value that depends on the car's position. By setting different detection levels at different positions, the system can control the collision speed with the shock absorber to be within a predetermined range, allowing the shock absorber to be optimized for a specific speed rather than designing for maximum possible speed.
2Reliability
If the shock absorber is enlarged to accommodate maximum collision speed, then the shock absorber can handle all possible collision scenarios, but the hoistway cannot be reduced in size
Solution Approach 1:
The patent applies preliminary action by setting the overspeed detection level in advance based on the car's position before the collision occurs. The system proactively controls the braking process to ensure the car reaches the shock absorber at a predetermined collision speed, rather than reacting after the collision risk arises. This preliminary control allows the shock absorber to be sized for a specific, controlled collision speed, enabling hoistway size reduction.
3Speed
If the overspeed detection level is set high to allow faster car operation, then the car can operate at higher speeds, but the collision speed with the shock absorber increases requiring a larger shock absorber
Solution Approach 1:
The patent applies local quality by setting different overspeed detection levels for different positions in the hoistway. The detection level is locally optimized for each position, allowing the car to operate at higher speeds in certain zones while ensuring controlled collision speed near the shock absorber. This localized adjustment enables high-speed operation without requiring the shock absorber to be oversized for maximum collision speeds.
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 solution enables efficient performance of the shock absorber by ensuring consistent collision speeds, allowing for a smaller shock absorber and a reduced hoistway size, while providing reliable braking mechanisms to prevent collisions.
Implementation Method 1
a shock absorber for absorbing a shock caused to a car at a bottom within a hoistway
Implementation Method 2
a braking device for braking a movement of the car
Data Source
Figure 1~2
Figure 3~5
Figure 6~7
AI summary
A shock absorber for a car is provided at a bottom within a hoistway. A hoisting machine is provided with a hoisting machine brake device for braking a movement of the car. A safety device controls an operation of the hoisting machine brake device when there is an abnormality in a speed of the car such that the speed of the car becomes equal to or lower than an allowable collision speed of a shock absorber before the car reaches a position of the shock absorber. The safety device starts the operation of the hoisting machine brake device when the speed of the car exceeds an overspeed detection level. A value of the overspeed detection level in a predetermined interval from the position of the shock absorber is set in accordance with a position of the car such that the speed of the car becomes equal to the allowable collision speed of the shock absorber at the position of the shock absorber through braking of the car by the hoisting machine brake device.