Push-Pull Voice Coil Compressor for Balanced Cryocooler Efficiency

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Solution Overview

Problem

Cryocooler designs are inefficient due to compressor motor inefficiencies and exported forces caused by mismatches in piston forces, leading to high power requirements and increased complexity, weight, and cost.

Innovation Solution

A push-pull compressor design using voice coil actuators with magnets and coils embedded within or coupled to projections on opposing pistons, allowing them to push or pull each other, which reduces exported forces and increases efficiency by matching masses and suspension resonances, potentially reducing input power requirements by up to 30-40%.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If traditional compressor motors are used in cryocoolers, then the system can achieve compression function, but the efficiency is poor and power consumption is high

Engineering Contradiction:
Improvecompressor efficiencyVSAvoidinput power requirement
Core Design Contradiction:
Use of energy by moving objectVSPower

Solution Approach 1:

The patent replaces traditional electromagnetic compressor motors with a voice coil actuator system that uses electromagnetic fields to directly drive piston movement. The voice coil generates a varying electromagnetic field that attracts and repels magnets on opposing pistons, eliminating the need for traditional motor-mechanism conversions and reducing energy loss.

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

Solution Approach 2:

The voice coil actuator operates by generating periodic varying electromagnetic fields that repeatedly attract and repel the magnets on opposing pistons. This periodic electromagnetic action directly translates to periodic piston movement, enabling efficient compression cycles with reduced energy consumption compared to continuous motor operation.

Inventive Principle:
Principle #19Periodic action

2Object-generated harmful factors

If opposing pistons are used to provide compression, then compression function is achieved, but mismatches in piston forces generate exported forces that affect other components

Engineering Contradiction:
Improveexported forcesVSAvoidsystem stability
Core Design Contradiction:
Object-generated harmful factorsVSReliability

Solution Approach 1:

The patent uses opposing pistons with magnets that generate counteracting forces. When the voice coil attracts one magnet, it simultaneously repels the other magnet with equal force in the opposite direction. These opposing forces balance each other out, canceling exported forces and preventing detrimental effects on other system components.

Inventive Principle:
Principle #8Anti-weight (Counterweight)

Solution Approach 2:

The patent employs asymmetric magnet placement and voice coil positioning to create balanced opposing forces. By strategically positioning magnets on projections extending from opposing pistons and configuring the voice coil geometry, the system achieves force balance that eliminates net exported forces while maintaining compression functionality.

Inventive Principle:
Principle #4Asymmetry

3Use of energy by moving object

If voice coil actuators are used with magnets and coils embedded within or coupled to projections on opposing pistons, then efficiency increases and exported forces are reduced, but the device complexity increases

Engineering Contradiction:
Improvecompressor efficiencyVSAvoidcompressor structure
Core Design Contradiction:
Use of energy by moving objectVSDevice complexity

Solution Approach 1:

The patent embeds magnets within projections that extend from the piston bodies, and integrates voice coil structures that couple to these projections. This nested configuration allows the actuator components to be compactly arranged within the existing compressor structure, minimizing additional space requirements and reducing overall system complexity despite the advanced actuation mechanism.

Inventive Principle:
Principle #7Nested doll (Nesting)

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 design achieves ultra-high efficiency by doubling mechanical work output and passively reducing or eliminating exported forces, thereby simplifying the system, reducing weight and cost, and maintaining symmetry, which enhances the overall performance of cryocoolers.

Implementation Method 1

generating a first varying electromagnetic field using a first voice coil of a first voice coil actuator; and repeatedly attracting and repelling a first magnet of the first voice coil actuator based on the first varying electromagnetic field

Methodology Applied
Scientific EffectElectromagnetic field: Electromagnetic Induction

Data Source

PatentEP3669076B1Push-pull compressor having ultra-high efficiency for cryocoolers or other systems
Publication Date: 2021.09.15 RAYTHEON CO
  • EP3669076B1 patent drawingFigure 1
  • EP3669076B1 patent drawingFigure 2
  • EP3669076B1 patent drawingFigure 3

AI summary

A method includes generating (602, 608) a first varying electromagnetic field using a first voice coil (122, 222a, 322, 422a) of a first actuator. The method also includes repeatedly attracting (606) and repelling (610) a first magnet (118, 218a, 318, 418a) of the first actuator based on the first varying electromagnetic field. The first voice coil is connected to a first piston (102, 202, 302, 402) of a compressor (100, 200, 300, 400, 502), and the first magnet is connected to an opposing second piston (104, 204, 304, 404) of the compressor. Attracting the first magnet narrows a space (108, 208, 308, 408) between the pistons, and repelling the first magnet enlarges the space between the pistons. The method may further include generating (602, 608) a second varying electromagnetic field using a second voice coil (122, 222b, 422b) of a second actuator and repeatedly attracting (606) and repelling (610) a second magnet (218b, 418b) of the second actuator based on the second varying electromagnetic field. The second voice coil may be connected to the second piston, and the second magnet may be connected to the first piston.