Screw Compressor Inlet Valve Startup Torque Reduction
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Solution Overview
Problem
Existing devices for adjusting the flow rate of mobile oil-injected screw-type compressors face challenges with low torque during cold startup and high fuel consumption, as the inlet valve is often pushed open by a compression spring, hindering the compressor's speed increase and requiring excessive fuel for operation.
Innovation Solution
Incorporating a non-return valve actuated by control pressure and a bypass line with a normally closed load valve to maintain the inlet valve in a closed position during startup, reducing the torque required and minimizing fuel consumption by allowing direct pressure application to the valve element, thus preventing unnecessary air compression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the inlet valve is pushed open by a compression spring during startup, then the valve is automatically open for gas intake, but the compressor requires high torque and consumes excessive fuel to overcome air compression
Solution Approach 1:
The system performs preliminary action by keeping the inlet valve closed during the startup phase until the compressor reaches minimum rotational speed. The control pressure buildup occurs in advance to ensure the valve remains closed during the critical acceleration phase, preventing unnecessary air compression and reducing fuel consumption.
Solution Approach 2:
The inlet valve position is made dynamic rather than static. The valve element responds to changing control pressure conditions, automatically transitioning from closed during startup to open during normal operation. This dynamic control allows the system to optimize performance at different operating phases.
2Use of energy by moving object
If the inlet valve is kept closed during startup until minimum rotational speed is reached, then fuel consumption is reduced, but the valve requires complex control mechanisms to maintain closed position
Solution Approach 1:
The control system is self-regulating through the natural buildup of control pressure as the compressor operates. The control pressure automatically increases with operating conditions, eliminating the need for external control signals or complex actuation mechanisms. The system serves itself by using its own operational parameters to control the valve.
Solution Approach 2:
The valve control utilizes pneumatic principles by employing control pressure derived from the compressor's own operating conditions. The control pressure line connects to the valve element, using gas pressure to maintain the closed position during startup and automatically opening the valve when control pressure drops during normal operation.
3Ease of operation
If a compression spring is used to push the inlet valve open during startup, then the valve opens automatically, but the spring adds complexity and the valve cannot remain closed during startup
Solution Approach 1:
The invention extracts and removes the compression spring from the valve mechanism. Instead of using a spring to push the valve open, the system relies on control pressure management to keep the valve closed during startup. This extraction eliminates the spring mechanism's complexity while achieving the desired valve control functionality.
Solution Approach 2:
Instead of using a spring to actively open the valve (positive action), the system uses control pressure to actively keep the valve closed (negative action). The valve opens not through spring force but through the release of control pressure, inverting the conventional approach to valve actuation.
4Productivity
If the inlet valve is opened during startup, then gas can be drawn in immediately, but the compressor cannot accelerate to required speed due to air compression
Solution Approach 1:
The system performs preliminary action by maintaining a closed inlet valve during the acceleration phase. The valve remains closed until the compressor reaches minimum rotational speed, ensuring that no air is drawn in during the critical acceleration period. This preliminary closure of the valve enables the compressor to accelerate to the required speed without the hindrance of air compression.
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 solution simplifies the startup process by reducing torque requirements and lowers fuel consumption, allowing the compressor to operate efficiently and economically by maintaining the inlet valve in a closed position until the minimum rotational speed is reached.
Implementation Method 1
a non-return valve actuated by means of a spring which can be pushed open by the control pressure
Implementation Method 2
a non-return valve actuated by means of a spring which can be pushed open by the control pressure
Implementation Method 3
while the screw-type compressor increases speed from a standstill up to the required minimum rotational speed, air is drawn in and compressed
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
Improved device (7) for adjusting the flow rate of a screw- type compressor (1) supplying compressed gas, consisting of a control valve (14) which supplies a control pressure (Pn) which is in proportion to the gas pressure (Pw) as of a gas pressure (A) ; an electronic speed controller (20) which sets a lower rotational speed (N) as the control pressure (Pr1) rises; an inlet valve (8) controlled by the control pressure (Pr1) with a valve element (10) which can freely move inside a housing (9) and whereby a non-return valve (22) actuated by means of a spring (23) is provided in a line (21) between the inlet valve (8) and the control valve (14) .