Comminution Rotor Drive Slip Control via Frequency Converter
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Solution Overview
Problem
Conventional comminution devices with belt drives face issues of significant wear and tear, complex operation, and frequent interruptions due to material accumulation, leading to high maintenance needs and potential damage from shock loads and non-crushable impurities.
Innovation Solution
A method that regulates traction mechanism slip by controlling the frequency converter to reduce torque when a second slip threshold is exceeded, minimizing wear and maintaining continuous operation by adjusting the slip mode to prevent excessive slip and maintain rotor speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a non-positive belt drive is used instead of a toothed gear drive, then the device becomes more insensitive to shock loads and damping is improved, but significant wear and tear occurs leading to short maintenance intervals
Solution Approach 1:
The control system dynamically adjusts the motor torque based on real-time slip detection. When slip exceeds a threshold indicating impurity presence, the controller reduces torque to prevent belt damage. This dynamic adaptation allows the belt drive to handle shock loads from impurities without suffering excessive wear, extending maintenance intervals while maintaining shock load insensitivity.
Solution Approach 2:
The system implements feedback control by monitoring traction mechanism slip and using this information to adjust motor torque. The slip signal serves as feedback that triggers torque reduction when impurities are detected, preventing excessive wear during abnormal operating conditions while maintaining normal operation during standard conditions, thereby extending maintenance intervals.
2Reliability
If the electric motor is switched off when slip exceeds a threshold, then damage from impurities is avoided, but operation is interrupted requiring frequent stopping
Solution Approach 1:
Instead of completely switching off the motor when slip occurs, the system applies partial action by reducing torque to a lower level that is sufficient to continue operation but gentle enough to prevent belt damage during impurity passage. This partial torque reduction allows continuous operation while still protecting the drive system, maintaining productivity while ensuring reliability.
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 approach extends maintenance intervals, ensures uninterrupted operation, and reduces wear on the drive system by dynamically managing slip and torque, allowing for continuous comminution without excessive wear or interruptions.
Implementation Method 1
a three-phase electric motor, which is fed by a controlled frequency converter
Implementation Method 2
a non-positive traction drive, in particular a belt drive
Data Source
Figure 1
Figure 2a~2b
Figure 3
AI summary
A comminuting rotor is driven by a rotary current electric motor via a non-positive traction drive, wherein said rotary current electric motor is energized by a controlled frequency converter for operating the comminuting rotor at a predetermined rotational speed during the normal operating phase. A degree of slip of the traction drive is determined and monitored and the rotary current electric motor is controlled for being powered off if a first slip threshold value is exceeded. If a predetermined second threshold of the traction drive slip is exceeded, which is below said first slip threshold, for continuing the operation of the comminuting device, the frequency converter is controlled in a slip operating phase for a closed or open loop control of the traction drive slip to a predetermined third slip threshold value and for reducing the torque output from the rotary current electric motor.