Electronic Control for Oil-Injected Compressor Pressure

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Solution Overview

Problem

Pneumatic control systems for oil-injected compressor installations suffer from continuous compressed air loss, unstable operating pressure, high power consumption when unloaded, large time constants leading to pressure fluctuations, freezing issues, manual pressure setting limitations, and high inlet losses due to piston valve design.

Innovation Solution

An electrically controllable system with a butterfly valve driven by a stepping motor and a PID controller, connected to an electronic control unit, which adjusts operating pressure based on measured values and eliminates pneumatic pressure pipes, allowing remote pressure setting and improved control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If pneumatic control systems are used to control the inlet valve, then the valve can be actuated, but continuous loss of compressed air occurs

Engineering Contradiction:
Improveinlet valve controlVSAvoidcompressed air loss
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The patent replaces the pneumatic control system with an electronic control system. The inlet valve is actuated by an electronic motor (such as a servo motor or stepper motor) controlled by a control unit, eliminating the need for compressed air in the control mechanism while maintaining reliable valve actuation.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Reliability

If pneumatic control systems are used with regulating pressure pipes, then the inlet valve can be controlled, but large time constants cause pressure fluctuations and overshoots

Engineering Contradiction:
Improveinlet valve controlVSAvoidoperating pressure stability
Core Design Contradiction:
ReliabilityVSStability of the object's composition

Solution Approach 1:

The patent replaces the pneumatic control system with an electronic control system. The electronic control unit directly controls the inlet valve actuator without intermediary pneumatic components, eliminating large time constants and pressure fluctuations, thereby improving operating pressure stability.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent implements a feedback control mechanism where a pressure sensor continuously monitors the operating pressure and feeds this information back to the control unit. The control unit adjusts the inlet valve position based on the feedback signal to maintain stable operating pressure and prevent overshoots.

Inventive Principle:
Principle #23Feedback

3Ease of operation

If the compressor installation is unloaded with pneumatic control, then the compressor runs idle, but operating pressure remains high requiring more power

Engineering Contradiction:
Improveunloaded operationVSAvoidpower consumption
Core Design Contradiction:
Ease of operationVSUse of energy by moving object

Solution Approach 1:

The patent replaces the pneumatic control system with an electronic control system that can precisely control the inlet valve opening degree. This allows the compressor to operate at reduced capacity with lower power consumption while maintaining stable operating pressure, even when unloaded or partially loaded.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent implements dynamic control of the inlet valve opening degree based on actual load conditions. The control unit continuously adjusts the valve position to match the required compressed air demand, enabling the compressor to operate efficiently across varying load conditions rather than maintaining fixed high pressure.

Inventive Principle:
Principle #15Dynamics

4Reliability

If piston valves are used for inlet control, then the valve can be actuated, but large inlet losses occur

Engineering Contradiction:
Improveinlet valve actuationVSAvoidinlet losses
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The patent replaces the mechanical piston valve with an electronically controlled valve mechanism. This new design reduces inlet losses by improving flow characteristics and reducing turbulence, while electronic actuation maintains reliable valve control.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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

The system reduces power consumption, stabilizes operating pressure, minimizes pressure fluctuations, prevents freezing, and decreases inlet losses, enabling efficient and precise control of compressor installations.

Implementation Method 1

butterfly valve that is driven by a stepping motor

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 2

inlet pressure controller which is made in the shape of a PID controller with a reinforcement, whereby this reinforcement is a function of the position of the inlet valve or of the relation between the absolute pressure following the inlet valve at the air inlet of the compressor element and the absolute pressure on the inlet side of the inlet valve

Methodology Applied
Scientific EffectFeedback control: Feedback

Data Source

PatentEP2027392B1Device for regulating the operating pressure of an oil-injected compressor installation
Publication Date: 2015.11.18 ATLAS COPCO AIRPOWER NV
  • EP2027392B1 patent drawingFigure 1
  • EP2027392B1 patent drawingFigure 2
  • EP2027392B1 patent drawingFigure 3~4

AI summary

Device for adjusting the operating pressure of an oil-injected compressor installation with a compressor element (2) driven by a motor (4) with an adjustable rotational speed and a control module (13), whereby the device (15) is provided with a controlled inlet valve (16) which is connected to the air inlet (5) and a blow-off mechanism (17) which can be closed by means of a blow-off valve (19), characterised in that the above-mentioned inlet valve (16), the blow-off valve (19) and the control module (13) are electrically controllable components which are connected to an electronic control unit (22) for adjusting the operating pressure (Pw), which is measured by an operating pressure sensor (23).