Linear Compressor Piston Travel Limiting via Magnetic Repulsion

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Solution Overview

Problem

Conventional refrigerant compressors with linear drives face challenges in precisely limiting piston travel without mechanical spring elements or complex electronic controls, leading to mechanical wear and inefficiencies.

Innovation Solution

The use of permanent magnet arrangements on the piston and cylinder housing to create a repelling effect, limiting piston travel at top and bottom dead centers without the need for electronic sensors or mechanical springs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If mechanical spring elements are used to limit piston travel, then the piston is prevented from hitting the cylinder head, but mechanical wear occurs in the spring elements and piston components

Engineering Contradiction:
Improvepiston travel limitationVSAvoidmechanical wear
Core Design Contradiction:
ReliabilityVSObject-generated harmful factors

Solution Approach 1:

The patent replaces mechanical spring elements with a magnetic field-based limitation system. Permanent magnets arranged on the piston and cylinder housing create magnetic repulsion forces that limit piston travel without physical contact, eliminating mechanical wear while maintaining reliable piston travel limitation.

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

Solution Approach 2:

The patent introduces magnetic fields as an intermediary between the piston and cylinder head. The magnetic repulsion force acts as a non-contact mediator to prevent the piston from hitting the cylinder head, replacing the need for direct mechanical contact through spring elements.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Measurement precision

If complex electronic sensors and controls are used to limit piston travel, then precise control is achieved, but device complexity and cost increase

Engineering Contradiction:
Improvepiston travel control precisionVSAvoidelectronic control system
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent implements a self-regulating system where the piston itself generates the limiting force through permanent magnets attached to it. The magnetic repulsion automatically limits piston travel based on the physical distance between magnets, eliminating the need for external sensors, controllers, or complex electronic systems.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent replaces complex electronic sensing and control systems with a passive magnetic field-based limitation mechanism. The magnetic repulsion provides inherent, contactless feedback that automatically limits piston travel without requiring electronic measurement or control circuitry.

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

3Productivity

If the piston stroke is increased to improve refrigeration capacity, then more refrigerant can be compressed, but the piston may hit the cylinder head or create excessive dead space

Engineering Contradiction:
Improverefrigeration capacityVSAvoidpiston travel limitation
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent enables variable piston stroke by adjusting the strength and configuration of magnetic fields. By changing magnetic field parameters (such as magnet strength or arrangement), the piston travel distance can be optimized for different refrigeration capacity requirements while maintaining reliable limitation and avoiding piston-cylinder head contact.

Inventive Principle:
Principle #35Parameter changes

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 simple, reliable method to restrict piston movement, reducing mechanical wear and dead space, while allowing for adjustable refrigeration capacity and efficiency by varying the magnetic field configuration.

Implementation Method 1

at least one first permanent magnet arranged on the piston or on a component connected to the piston and at least one second permanent magnet arranged on the cylinder housing or on a component connected to the cylinder housing, the at least one first permanent magnet and the at least one second permanent magnet each pointing towards one another with the same magnetic pole direction in order to limit the piston travel in the area of top dead center and/or in the area of bottom dead center when the at least one first permanent magnet approaches the at least one second permanent magnet, a repelling effect between the two permanent magnets

Methodology Applied
Scientific EffectMagnetic repulsion: Magnetism

Implementation Method 2

a linear drive is provided, comprising at least one oscillating body surrounded by an excitation winding, which is connected to the piston in order to move it in an oscillating manner along a piston longitudinal axis

Methodology Applied
Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP2513479B1Coolant compressor with linear drive
Publication Date: 2015.08.19 SECOP AUSTRIA
  • EP2513479B1 patent drawingFigure 1~2
  • EP2513479B1 patent drawingFigure 3~4
  • EP2513479B1 patent drawingFigure 5~6

AI summary

The invention relates to a coolant compressor with a hermetically sealed compressor housing, in the interior of which lies a piston cylinder unit (21) that compresses a coolant. The cylinder housing (1) of said piston cylinder unit is closed at the front end thereof by means of a cylinder head (4), said piston cylinder unit (21) having at least one piston (3). A linear drive (6) is provided, comprising at least one oscillating body (7) which is surrounded by an excitation winding (8) and which is connected to the piston (3) in order to move same along a longitudinal axis (9) of the piston in an oscillating manner. According to the invention, the piston cylinder unit (21) is equipped with at least one permanent magnet arrangement, each permanent magnet arrangement comprising at least one first permanent magnet (11) that lies on the piston (3) and at least one second permanent magnet (12) that lies on the cylinder housing (1). Both the first permanent magnet (11) and the second permanent magnet (12) face each other and are oriented in the same magnetic pole direction in order to generate a repelling effect between both permanent magnets (11, 12) to limit the path of the piston in the region of the top dead center and/or in the region of the bottom dead center.