Lubricant-Sealed Vacuum Pump Speed Control for Smaller Filters
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Solution Overview
Problem
Existing lubricant-sealed vacuum pumps require large filters to handle maximum fluid flow rates during initial chamber evacuation, leading to oversized designs for most of the pump's operation time.
Innovation Solution
Implementing control circuitry to regulate the rotor's rotational speed, reducing it initially when pressure is high to manage flow rates below the filter's capacity, allowing for a smaller filter size and acceptable pump-down time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the filter is sized to handle maximum fluid flow rate during initial chamber evacuation, then the filter can effectively filter exhaust gases, but the filter becomes oversized for most of the pump's operation time
Solution Approach 1:
The pump employs variable speed operation where the rotor rotates at a selected reduced speed during initial chamber evacuation and at a higher operational speed during normal operation. This dynamic speed adjustment allows the system to use a smaller filter sized for reduced flow rates while maintaining effective filtration throughout the pump's operation cycle.
Solution Approach 2:
The control circuitry changes the rotational speed parameter of the rotor based on operating conditions. By reducing the speed during initial evacuation when flow rate is highest, the system maintains filtration effectiveness with a smaller filter, as the actual flow rate through the filter remains within its designed capacity.
2Productivity
If the rotor rotates at higher operational speed throughout, then the pump achieves faster evacuation, but the flow rate through the filter exceeds the maximum flow rate the filter has been configured to support
Solution Approach 1:
The system dynamically adjusts rotor speed based on the pumping phase. During initial evacuation, the rotor operates at a reduced speed to keep flow rate within the filter's maximum capacity. Once the chamber pressure reduces to operational levels, the rotor speed increases to higher operational speed for optimized productivity.
Solution Approach 2:
The control circuitry implements preliminary reduced-speed operation during the initial evacuation phase before transitioning to higher speed. This preliminary action prevents excessive flow rates from overwhelming the filter, ensuring reliable operation throughout the entire pumping cycle.
3Reliability
If the rotor rotates at reduced speed for a predetermined period, then the flow rate through the filter remains below maximum capacity, but the time required to pump the chamber down to working pressure is increased
Solution Approach 1:
The control circuitry changes the rotor speed parameter based on operating conditions. By reducing speed only during the initial evacuation phase when flow rate is highest, the system manages filter load effectively. The predetermined period of reduced-speed operation is optimized to balance filter protection with acceptable pump-down time.
Data Source
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AI summary
A lubricant-sealed vacuum pump configured to pump fluid from an inlet to an exhaust, method and filter are disclosed. The lubricant-sealed vacuum pump comprises: a rotor; a filter for filtering lubricant from fluid to be output by the pump; control circuitry for controlling a speed of rotation of the rotor, the control circuitry being configured to control rotation of the rotor, such that the rotor rotates at a reduced speed initially when a pressure at the inlet is high and rotates at a higher operational speed when the pressure at the inlet has reduced.