Magnetic Levitation Molecular Pump Rotor Dynamic Balancing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The method of rotor dynamic balancing for magnetic levitation molecular pumps is inconvenient and inefficient, requiring multiple steps and additional equipment, which increases costs and limits the ability to accelerate the rotor beyond its rigid critical speed.
Innovation Solution
A method utilizing an open loop feed forward control module to inhibit co-frequency vibrations, allowing high-speed dynamic balancing without additional equipment, using first and second radial displacement sensors to calculate balance mass and phase, and employing balance planes for enhanced force compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional rotor dynamic balancing method is used, then balancing can be achieved, but it requires multiple steps and additional balancing devices, increasing costs and reducing efficiency
Solution Approach 1:
The patent extracts the balancing function from traditional external balancing devices and integrates it into the pump's existing control system. The control system uses radial displacement sensors already present in the magnetic bearing system to detect vibration and calculate imbalance, eliminating the need for separate balancing equipment.
Solution Approach 2:
The control system performs multiple functions: it controls the magnetic bearings for levitation and simultaneously performs dynamic balancing. The radial displacement sensors serve both for position control and vibration detection, and the control algorithm handles both stabilization and imbalance compensation.
2Manufacturing precision
If traditional rotor dynamic balancing method is used, then balancing can be achieved, but it requires multiple steps and additional balancing devices, increasing time consumption
Solution Approach 1:
The system performs balancing measurements during the normal operation and commissioning phase of the pump, before the pump is put into final service. The control system automatically detects imbalance characteristics and calculates correction values, allowing balancing to be completed during initial setup rather than requiring separate maintenance interventions.
Solution Approach 2:
The balancing process is integrated into the continuous operation of the pump. The control system continuously monitors radial displacement and vibration during rotation, allowing for real-time detection and calculation of imbalance without stopping the pump or requiring separate balancing operations.
3Manufacturing precision
If imbalance mass is large, then the rotor can be balanced, but the centrifugal force causes transverse mechanical vibration and prevents the rotor from reaching normal working speed
Solution Approach 1:
The control system uses radial displacement sensors to continuously monitor the rotor's radial position and vibration during rotation. The detected vibration signals are fed back to the control algorithm, which calculates the imbalance characteristics and determines the necessary compensation forces to apply through the magnetic bearings.
Solution Approach 2:
The system changes the operational parameters by operating the rotor at multiple different speeds during the balancing process. By measuring vibration at various speeds including above and below the critical speed, the control algorithm can accurately determine imbalance characteristics and calculate effective compensation values that work across the entire operating range.
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 method enables efficient and convenient high-speed rotor dynamic balancing, reducing costs and improving balancing efficiency, allowing the rotor to stabilize at rated rotational speeds with reduced imbalance mass and vibration thresholds.
Implementation Method 1
a magnetic bearing (also known as active magnetic levitation bearing) as a bearing for the rotor of the molecular pump, and the rotor is suspended in the air stably through the magnetic bearing
Implementation Method 2
detecting a radial vibration amplitude of the rotor
Implementation Method 3
generate a compensation signal having a same phase and a same amplitude with a displacement/vibration signal of the rotor, in order to counteract same frequency of vibration of the rotor
Implementation Method 4
the product of this mass and centripetal acceleration equals to the rotor's imbalance centrifugal force. When the imbalance mass is much larger than 10 mg, due to this imbalance mass, an eccentric moment may be generated between the barycenter of the rotor and its axis. Therefore, during the rotating ascend of the rotor, the centrifugal force caused by the imbalance mass of the rotor may cause transverse mechanical vibration of the rotor
Data Source
AI summary
A rotor dynamic balancing method for a magnetic levitation molecular pump, which includes the steps of activating an open loop feed forward control module after activating a motor of the magnetic levitation molecular pump; if the maximum radial vibration amplitude does not exceed ½ of a protective clearance during the acceleration of the rotor under the control of the open loop feed forward control module, indicating that the open loop feed forward control module is able to inhibit the co-frequency vibration of the rotor, so as to allow the rotational speed of the rotor to exceed its rigid critical rotational speed; and performing a rotor dynamic balancing operation at a high speed by an influence coefficient method. This method directly performs the rotor dynamic balancing operation with respect to the rotor at a high-speed, which facilitates the rotor dynamic balancing operation so as to perform the rotor dynamic balancing operation more quickly and efficiently.