Electromagnetic Actuator for Reciprocating Compressor

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Solution Overview

Problem

Reciprocating compressors face limitations in flexibility and efficiency due to fixed piston travel and high inertial forces, making it difficult to vary gas displacement and compression capacity in response to changing gas demand, and existing linear motor technology is unsuitable for phased operation.

Innovation Solution

The use of double or single electromagnetic actuators with resonance springs allows for phased control of piston movement, enabling variable compression capacity by dynamically adjusting the phase angle and reducing inertial forces through the combination of electromagnetic forces and resilient members.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a rotatory motor with crankshaft and connecting rod is used to drive the piston, then the piston can be driven reliably, but the piston travel is fixed and the machine cannot adapt to changing gas demand

Engineering Contradiction:
Improvepiston travel adjustmentVSAvoidmechanical linkage complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent replaces the traditional rotatory motor with crankshaft and connecting rod mechanism with a linear motor that directly drives the piston along the cylinder axis. This substitution eliminates the mechanical linkage complexity while enabling variable piston travel through electronic control of the linear motor, thus resolving the contradiction between adaptability and device complexity.

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

2Adaptability or versatility

If the operating speed is changed to vary the volume of gas pumped, then the pumping capacity can be adjusted, but the efficiency is reduced and vibration frequency changes

Engineering Contradiction:
Improvepumping capacity adjustmentVSAvoidmotor efficiency
Core Design Contradiction:
Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

The patent changes the control parameter from operating speed to piston stroke length. By varying the piston travel distance while maintaining constant operating speed, the system achieves variable pumping capacity without the efficiency losses and vibration frequency changes associated with speed variation. This is accomplished through electronic control of the linear motor's stroke length.

Inventive Principle:
Principle #35Parameter changes

3Volume of stationary object

If existing linear motor technology is used to drive opposed pistons, then the machine can be compact, but the high inertial rod loads exceed the force capability of available linear motors

Engineering Contradiction:
Improvecompressor sizeVSAvoidlinear motor force capability
Core Design Contradiction:
Volume of stationary objectVSForce

Solution Approach 1:

The patent employs periodic action by coordinating the reciprocating motion of opposed pistons in a specific phase relationship. The inertial loads from opposing pistons cancel each other out when properly phased, dramatically reducing the net force requirement on the linear motor. This enables compact design with available linear motor technology despite the high inertial loads.

Inventive Principle:
Principle #19Periodic action

4Volume of stationary object

If oppositely arranged pistons are used in a standard reciprocating compressor, then the machine can be compact, but varying the phase between pistons is difficult and slow

Engineering Contradiction:
Improvecompressor sizeVSAvoidphase adjustment
Core Design Contradiction:
Volume of stationary objectVSEase of operation

Solution Approach 1:

The patent replaces mechanical phase adjustment mechanisms with electronic control of the linear motor. By using electronic commutation and control algorithms, the phase relationship between opposed pistons can be rapidly and precisely adjusted without mechanical linkages, resolving the contradiction between compact design and ease of phase adjustment.

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

This solution provides a compact, efficient compressor that can adapt to changing gas demand by varying piston phase and stroke length, minimizing drive force requirements and maintaining energy efficiency.

Implementation Method 1

an electromagnetic actuator positioned inside the cylinder bore and adapted to exert an oscillating electromagnetic force along the axis on the piston rod

Methodology Applied
Scientific EffectElectromagnetic force: Lorentz Force

Implementation Method 2

a resilient member having a first end coupled to the piston rod and a second end coupled to the cylinder head, the resilient member being configured to reduce inertial forces on the piston rod

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP2861868B1Electromagnetic actuator for a reciprocating compressor
Publication Date: 2020.03.04 NUOVO PIGNONE SPA
  • EP2861868B1 patent drawingFigure 1
  • EP2861868B1 patent drawingFigure 2~3
  • EP2861868B1 patent drawingFigure 4

AI summary

A compressor includes a pair of opposed pistons 42, 44 disposed in a housing 41 and defining a compression chamber 43. An electromagnetic actuator 20 reciprocatedly drives the pistons 42, 44 within the housing in cooperation with force accumulator. The force accumulators bank the force during a first reciprocation, decelerating the pistons 42, 44, and apply the force in a subsequent reciprocation, thereby accelerating the pistons. In one embodiment, two electromagnetic actuators drive the compression pistons. In another embodiment, a single electromagnetic actuator drives the compression pistons. A system and method of operation are disclosed.