Controller unit for controlling the speed of a motor driving an oil injected compressor and method of controlling said speed
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Solution Overview
Problem
Existing oil injected compressors face condensate formation issues, which can damage components due to corrosive effects, and existing solutions require significant design changes and increased maintenance costs.
Innovation Solution
A controller unit that connects with measuring means to determine a minimum motor speed based on working pressure, ambient temperature, and dew point, adjusting the motor speed to maintain the system temperature above the condensation point, thereby preventing condensate formation without major interventions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the temperature of the compressed gas is controlled by adjusting the flow of injected oil through a mixing valve, then the temperature can be maintained above the dew point to avoid condensate formation, but the piping and overall structure would require significant design changes that are not feasible for existing units
Solution Approach 1:
The invention changes the operating parameters of the existing compressor by controlling the motor speed to regulate the temperature of the compressed gas. By adjusting the speed of the motor driving the compressor elements, the temperature rises proportionally to the cube of the speed ratio, allowing temperature control without modifying the physical piping or structure of existing units.
Solution Approach 2:
The invention replaces the mechanical mixing valve system with an electronic control system that regulates motor speed. Instead of using a physical mixing valve to control oil flow and temperature, the system uses electronic sensors and a control unit to adjust the motor speed, thereby controlling the compression temperature directly.
2Reliability
If a mixing valve system is implemented to control temperature, then condensate formation can be prevented, but the complexity of the overall design increases the frequency of maintenance and its costs
Solution Approach 1:
The control system automatically monitors and adjusts motor speed to maintain optimal temperature, eliminating the need for manual intervention in temperature control. The system self-regulates by comparing measured temperature with target temperature and automatically adjusting motor speed accordingly, reducing maintenance requirements.
Solution Approach 2:
The invention implements a feedback control system where temperature sensors continuously monitor the compressed gas temperature, and the control unit adjusts motor speed based on the difference between measured and target temperatures. This closed-loop control ensures reliable condensate prevention while simplifying maintenance compared to mechanical mixing valve systems.
3Duration of action of stationary object
If the motor speed is controlled to maintain temperature above dew point, then condensate formation is prevented and component lifetime is increased, but additional measuring means and control complexity are introduced
Solution Approach 1:
The control system integrates multiple functions into a single unit: it measures temperature, calculates dew point, determines optimal motor speed, and controls the motor all through one control unit. The system can be applied to various compressor types and configurations, making it a universal solution that doesn't require separate dedicated components for each function.
Data Source
AI summary
A controller unit for controlling the speed of a motor for driving an oil injected compressor, the controller unit including: a data connection; and a first module to receive data through the data connection. The controller unit includes a processing unit for determining a minimum working speed of the motor on the basis of the measured working pressure, the ambient temperature and a dew point temperature; and a comparator unit to compare the determined minimum working speed with the retrieved working speed of the motor. The processing unit includes a signal generating unit to send a signal to the motor for increasing the working speed of the motor to at least the determined minimum working speed, if the retrieved working speed is lower than the determined minimum working speed.