Moving Stop Plates for Linear Compressor Piston Return

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Solution Overview

Problem

Existing linear compressors rely on support springs that occupy large space, are expensive, and require operation at resonance frequencies, leading to inefficiencies in gas filling and increased dead volume due to dependency on natural frequency and variable piston stopping points.

Innovation Solution

The use of moving stop plates at the piston's top and bottom proximity surfaces in linear drive and free piston compressors to enable piston movement and return through increased gas pressure, eliminating the need for support springs and allowing for simplified operation independent of resonance frequencies.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If support springs are used to enable piston return movement, then the piston can return to starting position, but the springs occupy large space and increase device complexity

Engineering Contradiction:
Improvepiston return capabilityVSAvoidspace occupied by support springs
Core Design Contradiction:
Ease of operationVSVolume of stationary object

Solution Approach 1:

The patent removes the support springs from the system entirely and replaces them with a gas pressure-based return mechanism. The compression gas pressure acting on the piston bottom surface provides the necessary force to return the piston to its starting position, eliminating the need for separate spring components and their associated space requirements.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The invention uses gas pressure (pneumatics) to achieve piston return movement. By utilizing the compression gas pressure that is already present in the system, the patent converts this pressure into a mechanical force that pushes the piston back to its initial position, replacing the mechanical spring system with a pneumatic actuation mechanism.

Inventive Principle:
Principle #29Pneumatics and hydraulics

2Measurement precision

If support springs are used to ensure piston stopping at top dead center, then the piston can be positioned accurately, but the system requires operation at resonance frequencies reducing productivity

Engineering Contradiction:
Improvepiston stopping position accuracyVSAvoidcompressor operation speed flexibility
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The system uses the existing compression gas pressure to automatically return the piston to its starting position and stop it at the top dead center. The gas pressure itself serves the dual function of both compressing the gas and providing the return force, eliminating the need for separate positioning mechanisms and resonance frequency operation requirements.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The invention changes the control parameter from resonance frequency-dependent spring oscillation to direct gas pressure control. By using the gas pressure magnitude and timing to control piston movement and positioning, the system gains flexibility in operation speed without being constrained by natural frequency requirements.

Inventive Principle:
Principle #35Parameter changes

3Duration of action of moving object

If support springs are used for piston return, then the piston movement can be maintained, but the dead volume space increases reducing filling efficiency

Engineering Contradiction:
Improvepiston movement continuityVSAvoiddead volume gas amount
Core Design Contradiction:
Duration of action of moving objectVSQuantity of substance

Solution Approach 1:

The patent eliminates support springs and their associated mounting space, thereby reducing the dead volume space in the cylinder. The gas pressure return mechanism requires minimal additional space compared to the physical spring components, allowing for more effective utilization of the cylinder volume for gas compression.

Inventive Principle:
Principle #2Taking out (Extraction)

4Quantity of substance

If moving stop plates are introduced to control piston position, then dead space is reduced and filling efficiency improves, but device complexity increases

Engineering Contradiction:
Improvedead volume reductionVSAvoidnumber of moving parts
Core Design Contradiction:
Quantity of substanceVSDevice complexity

Solution Approach 1:

The moving stop plates serve multiple functions: they limit the piston travel to minimize dead volume, they assist in positioning the piston at top dead center, and they work in conjunction with the gas pressure return mechanism. By combining these functions into a single component, the patent reduces overall device complexity compared to having separate components for each function.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 reduces dead space, enhances filling efficiency by minimizing remaining gas, and simplifies the compressor structure by eliminating the need for support springs and resonance frequency compliance, enabling precise piston control and reduced operational complexity.

Implementation Method 1

enables for the piston to return by means of the increased gas pressure

Methodology Applied
Scientific EffectGas pressure: Pressure Increase

Data Source

PatentEP3250825B1Moving stop plate facility for linear compressors and increasing return gas pressure
Publication Date: 2019.09.18 DOKUZ EYLUL UNIVERSITESI REKTORLUGU
  • EP3250825B1 patent drawingFigure 1
  • EP3250825B1 patent drawingFigure 2
  • EP3250825B1 patent drawingFigure 3~4

AI summary

The invention subject to the application is related to an apparatus which enables to compress the gas into the space behind the moving plate by establishing moving stop plates (9, 12) at the bottom and top proximity surfaces of the pistons in linear drive and free piston compressors and enables for the piston to return by means of the increased gas pressure and by means of a spring force.