Vacuum Pump Speed Control for Rotor Clearance and Bearing Heat
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Solution Overview
Problem
Conventional vacuum pumps, particularly dry compression two-shaft pumps, face inefficiencies due to the need for a safety margin in rotor-stator distances and bearing temperatures, leading to reduced output and increased costs from complex and expensive sensor systems for monitoring operating parameters.
Innovation Solution
A vacuum pump with a control device and sensors that correlate operating parameters with critical parameters using machine learning algorithms, such as neural networks, to dynamically adjust rotor speed, eliminating the need for expensive sensors and ensuring optimal performance without exceeding critical limits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the distance between rotor element and stator/second rotor is increased to include a safety margin, then the reliability is improved, but the pump output is reduced
Solution Approach 1:
The patent applies dynamics by transitioning from a static safety margin design to a dynamic control system that continuously monitors operating parameters (temperature, rotational speed) and adjusts the rotor-stator distance accordingly. The control device modifies motor speed in real-time to maintain optimal spacing without requiring excessive clearance, thereby preserving pump output while ensuring reliability under varying operating conditions.
Solution Approach 2:
The patent utilizes parameter changes by monitoring temperature and rotational speed as key parameters and using them to dynamically adjust the operating state of the pump. The control device changes the motor speed parameter based on sensed operating conditions, which indirectly adjusts the rotor-stator distance and prevents contact while maximizing pump output for each operating scenario.
2Measurement precision
If complex sensors are used to sense the distance between rotor element and housing/second shaft, then the measurement precision is improved, but the device complexity and cost are increased
Solution Approach 1:
The patent employs an intermediary approach by using readily available sensors (temperature sensors, rotational speed sensors) as mediators to indirectly determine the rotor-stator distance. Instead of directly measuring the difficult-to-access spacing, the system uses temperature and speed data as intermediate parameters that correlate with the distance, allowing the control device to infer spacing conditions without complex direct measurement apparatus.
Solution Approach 2:
The patent replaces a potential complex mechanical measurement system with an electronic control system using standard sensors and computational logic. The control device substitutes direct mechanical distance sensing with an electronic feedback mechanism that calculates optimal motor speed based on temperature and rotational speed inputs, thereby reducing device complexity while maintaining measurement effectiveness.
3Reliability
If the maximum rotational speed of rotors is reduced to prevent bearing temperature from exceeding the limit, then the reliability is improved, but the pumping output is reduced
Solution Approach 1:
The patent applies dynamics by replacing a static rotational speed limit with a dynamic speed control system. The control device continuously monitors bearing temperature and adjusts the motor speed in real-time, allowing the rotors to operate at higher speeds when temperatures are acceptable and reducing speed only when necessary to prevent overheating. This dynamic approach maximizes pumping output while maintaining reliability under varying operating conditions.
Solution Approach 2:
The patent implements feedback control by using temperature sensors to monitor bearing temperature and feeding this information back to the control device. The control device processes the temperature feedback and adjusts the motor speed accordingly, creating a closed-loop system that automatically maintains bearing temperature within safe limits while optimizing pump output. This feedback mechanism eliminates the need for conservative static speed limits.
Data Source
AI summary
A vacuum pump includes a housing having an inlet and an outlet, at least one rotor arranged in the housing configured to convey a gaseous medium from the inlet to the outlet, a motor configured to rotate the rotor, a control device connected to the motor configured to control the motor, and at least one sensor connected to the control device. The at least one sensor is configured to sense at least one operating parameter of the vacuum pump. The control device comprises a correlation module. The correlation module is configured to correlate the sensed at least one operating parameter with at least one critical parameter. The motor is controlled on the basis of the at least one critical parameter.