Elevator Traction Control via Friction Monitoring
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Uncontrolled slip of elevator ropes on the traction sheave due to weakening traction poses safety risks and affects the stopping accuracy and transportation capacity of elevator systems, particularly due to factors like damage, temperature variations, and lubricant wear.
Innovation Solution
An elevator system with traction determination means and a control circuit that adapts the movement profile of the elevator car based on detected traction changes, reducing acceleration and deceleration when traction weakens and increasing them when traction improves, along with a machinery brake system for safety, to prevent uncontrolled slip and maintain safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the friction force between the traction sheave and elevator ropes is sufficient, then the elevator car can be driven with high acceleration and deceleration, but if the traction weakens, then uncontrolled slip occurs which compromises safety and stopping accuracy
Solution Approach 1:
The system performs preliminary detection of traction strength before the elevator car reaches critical speeds. The traction determination means measures the friction force between the traction sheave and ropes in advance, allowing the control circuit to pre-adjust acceleration and deceleration parameters to match the actual traction capacity, preventing uncontrolled slip before it occurs
Solution Approach 2:
The system continuously monitors traction strength through the traction determination means and uses this feedback to dynamically adjust the movement profile of the elevator car. The control circuit receives real-time data on friction force and modifies acceleration and deceleration rates accordingly, creating a closed-loop control system that adapts to changing traction conditions to maintain both speed and safety
2Productivity
If the movement profile is optimized for high speed, then transportation capacity increases, but if traction weakens, then uncontrolled slip occurs which affects stopping accuracy
Solution Approach 1:
The system transitions from a static, fixed movement profile to a dynamic, adaptable profile that changes in real-time based on measured traction strength. The control circuit continuously adjusts acceleration and deceleration rates according to the actual friction force between the traction sheave and ropes, allowing the system to optimize speed when traction is strong and reduce speed when traction weakens, thereby maintaining both transportation capacity and stopping accuracy
Solution Approach 2:
The system changes the parameters of the movement profile (acceleration and deceleration rates) based on the measured traction strength. When the traction determination means detects strong friction force, the control circuit allows higher acceleration and deceleration values to maximize transportation capacity. When traction weakens, the parameters are automatically reduced to prevent uncontrolled slip and maintain stopping accuracy
3Force
If the friction force is high, then the elevator ropes can transmit driving torque effectively, but if the coating is damaged or temperature varies, then traction weakens causing uncontrolled slip
Solution Approach 1:
The system replaces direct mechanical reliance on friction-based traction with an active measurement and control system. Instead of depending solely on the friction force between the traction sheave and ropes to prevent slip, the system uses the traction determination means to measure the actual friction force and the control circuit to actively manage the movement profile, substituting passive mechanical traction with an active controlled system that compensates for coating damage and temperature variations
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 system effectively prevents uncontrolled slip, ensures safety by automatically adjusting to traction changes, and enhances transportation capacity by optimizing movement profiles, thereby reducing the risk of accidents and improving operational efficiency.
Implementation Method 1
The friction force between the grooves of the traction sheave and the elevator ropes in the grooves compensates the aforementioned force difference caused by the weight difference of the elevator car and the counterweight. In addition, the friction force transmits driving torque to the elevator ropes from the motor drive
Implementation Method 2
The elevator car and the counterweight are suspended in the elevator hoistway such that their weight difference produces a force difference in the elevator ropes on the different sides of the traction sheave
Implementation Method 3
Since elongation of an elevator rope is proportional to the rope force according to a spring constant, rope elongation in the elevator ropes is different on the different sides of the traction sheave since the rope forces differ from each other on the different sides of the traction sheave
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to an elevator system and also to a method for ensuring the safety of an elevator system. The elevator system comprises a driving member (1) and also a hoisting means (3), which engages with the aforementioned driving member (1) by frictional traction. The elevator system comprises traction determination means (4, 5, 6A, 6B, 7) for determining the traction of the driving member (1), and the elevator system comprises a control circuit (4), which is configured to start a procedure ensuring the safety of the elevator system after the traction determination means (4, 5, 6A, 6B, 7) have detected that the traction of the driving member (1) has weakened.