Vacuum Pump Rotor Reversal for Inlet Valve Closure
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Solution Overview
Problem
Existing vacuum pumps with oil-lubricated systems face challenges in quickly isolating the inlet to prevent oil backflow when shut down, as the closure time of safety valves is influenced by oil viscosity and temperature, leading to variable and potentially prolonged isolation times.
Innovation Solution
The vacuum pump incorporates a drive unit that actively reverses the rotor's direction upon shutdown, compressing fluid to close the inlet valve quickly, supported by a triggering device and frequency converter for controlled operation, ensuring rapid valve closure independent of temperature and viscosity effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a spring biased safety valve is used to close the inlet automatically when the pump is shut down, then the inlet can be isolated from oil-lubricated areas, but the closing time varies with temperature and oil viscosity, leading to prolonged isolation times at low temperatures
Solution Approach 1:
The patent replaces the purely mechanical spring-biased safety valve system with an electromechanical system. An electric motor coupled to the rotor can actively reverse the rotor's rotation direction upon shutdown detection, providing controlled mechanical action to close the inlet valve. This substitution of mechanical reliance with electrical control enables faster and more consistent valve closing times independent of temperature and oil viscosity conditions.
Solution Approach 2:
The patent changes the operational parameters of the rotor by actively controlling its rotation direction. Upon shutdown detection, the drive unit reverses the rotor's rotation from the pumping direction to the opposite direction, creating a controlled backflow that actively pushes the inlet valve closed. This dynamic parameter change (rotation direction) provides a reliable and timely valve closing mechanism that overcomes the temperature-dependent delays of passive mechanical systems.
2Loss of energy
If the rotor is allowed to stop naturally when shut down, then energy consumption is reduced, but the inlet valve closes slowly due to oil viscosity and temperature effects
Solution Approach 1:
The patent implements a periodic action sequence where the rotor is first stopped, then actively reversed to rotate in the opposite direction for a predetermined period to ensure the inlet valve closes completely. This periodic operation (stop + reverse rotation) ensures timely valve closure while limiting energy consumption to only the necessary reversal period rather than continuous operation.
Solution Approach 2:
The control unit detects the shutdown condition and immediately triggers the rotor reversal before the natural stopping process completes. This preliminary active action ensures that the inlet valve begins closing early in the shutdown sequence, preventing delay caused by waiting for natural stop conditions to develop. The predetermined time control ensures the action is taken at the optimal moment to balance energy consumption with timely valve closure.
3Reliability
If the inlet valve is closed quickly to prevent oil backflow, then vacuum system reliability is improved, but the complexity of the control system increases
Solution Approach 1:
The control unit continuously monitors the pump's operational state and automatically triggers the rotor reversal upon detecting shutdown conditions. This feedback mechanism ensures the inlet valve closes at the precise moment needed to prevent oil backflow, maintaining vacuum system reliability. The automated feedback control eliminates the need for complex manual intervention systems while ensuring timely and reliable valve closure.
Solution Approach 2:
The system uses its own operational parameters (motor shutdown detection, rotor position sensing) to automatically initiate the valve closing sequence. The control unit leverages existing sensors and the motor's own operation status to trigger the reversal, making the system self-regulating. This self-service approach minimizes additional complexity by using the system's inherent capabilities to achieve reliable inlet isolation without external control systems.
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 enables the inlet valve to be closed within a short, predefined time, maintaining negative pressure and preventing oil backflow, thus enhancing the reliability and efficiency of vacuum system operation.
Implementation Method 1
The rotation of the rotor of the vacuum pump in the opposite direction to the direction of rotation when pumping the fluid causes the safety valve of the vacuum pump to close. This backflow of fluid via the outlet into the interior of the vacuum pump depends on the pressure difference between the interior of the vacuum pump and the area downstream of the outlet of the vacuum pump
Implementation Method 2
These passages ensure that in the event of an intentional or unintentional shutdown of the vacuum pump, a sufficient amount of fluid flows via the outlet into an interior space of the vacuum pump, thereby causing the rotor to rotate in a direction opposite to the direction required for conveying the fluid from the inlet
Implementation Method 3
a safety valve in the inlet area of the vacuum pump, which is automatically closed if the vacuum pump is switched off or fails, in order to isolate the oil-lubricated areas of the vacuum pump from upstream components of the vacuum system
Data Source
Figure 1
Figure 2
AI summary
A vacuum pump comprises an inlet (27) with an inlet valve (47), an outlet (29), a rotor (19) rotatably mounted in an interior (21) of the vacuum pump, and a drive unit (31) for the rotor (19). Rotation of the rotor (19) in a conveying direction (30) causes a fluid to be conveyed from the inlet (27) to the outlet (29) of the vacuum pump. The drive unit (31) is configured to rotate the rotor (19) in the opposite direction to the conveying direction when the vacuum pump is switched off or deactivated, thus assisting in the closing of the inlet valve (47).