Variable Volume Screw Compressor Discharge Port

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Solution Overview

Problem

Current screw compressors face inefficiencies due to fixed volume ratios, leading to overcompression or undercompression, which result in increased power consumption, noise, and reduced efficiency, especially when operating conditions change, as they are not adaptable to varying climate conditions.

Innovation Solution

A screw compressor with a variable volume ratio mechanism, where a movable plug in the discharge port allows for adjustments in volume ratio based on climate conditions, enabling efficient operation by maximizing or minimizing the discharge port volume, thus optimizing efficiency according to seasonal changes without requiring extensive disassembly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a fixed volume ratio compressor is designed for maximum compression under severe conditions, then reliability is improved, but efficiency deteriorates under milder operating conditions due to overcompression or undercompression

Engineering Contradiction:
Improvecompressor reliabilityVSAvoidenergy loss from overcompression or undercompression
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The discharge port volume is made variable through a movable plug that can be adjusted to different positions, allowing the compressor to dynamically adapt its volume ratio to matching operating conditions. This dynamic adjustment eliminates the need to design for maximum compression under all conditions, thereby reducing energy losses from overcompression or undercompression while maintaining reliability.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The physical parameter of discharge port volume is changed by moving the plug to different positions along the discharge port axis. This parameter change allows the volume ratio to be adjusted according to operating conditions, optimizing efficiency across different climates and operating scenarios without compromising the compressor's reliability.

Inventive Principle:
Principle #35Parameter changes

2Loss of energy

If the discharge port volume is increased to reduce compression ratio, then efficiency is improved under milder conditions, but the compressor cannot handle severe operating conditions effectively

Engineering Contradiction:
Improvecompression efficiencyVSAvoidadaptability to operating conditions
Core Design Contradiction:
Loss of energyVSAdaptability or versatility

Solution Approach 1:

The discharge port volume is made dynamically adjustable through the movable plug mechanism. The plug can be positioned to provide maximum volume for milder conditions or reduced volume for severe conditions, allowing the compressor to adapt its compression characteristics to match the actual operating environment and optimize efficiency across the full range of conditions.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The compressor is designed with a universal adjustment mechanism that enables it to perform optimally across multiple operating conditions. The movable plug allows the same compressor to be configured for different climates and operating scenarios, making it universally adaptable without requiring multiple specialized compressors.

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

3Adaptability or versatility

If a variable volume ratio mechanism is added to the compressor, then adaptability to operating conditions is improved, but device complexity increases

Engineering Contradiction:
Improvevolume ratio adjustabilityVSAvoidcompressor structure complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The adjustment mechanism is extracted as a separate, standalone component (the movable plug) that can be independently positioned and locked. This extraction allows the variable volume ratio functionality to be added with minimal integration complexity, as the plug operates independently within the discharge port without requiring complex control systems or multiple moving parts.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The movable plug is designed to be self-contained with its own positioning and locking mechanisms. The adjustment can be performed manually or through simple actuation, and the plug maintains its position without requiring continuous external control. This self-service design minimizes the complexity of the overall control system while providing effective variable volume ratio control.

Inventive Principle:
Principle #25Self-service

4Adaptability or versatility

If the compressor is designed for maximum compression, then it can handle severe operating conditions, but it operates inefficiently in milder conditions due to overcompression

Engineering Contradiction:
Improvehandling of severe conditionsVSAvoidovercompression energy loss
Core Design Contradiction:
Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The discharge port volume is dynamically adjusted by moving the plug to provide maximum compression capability when severe conditions require it, while reducing the volume ratio for milder conditions to eliminate overcompression. This dynamic adaptation allows the compressor to maintain optimal efficiency across the full spectrum of operating conditions without being permanently designed for maximum compression only.

Inventive Principle:
Principle #15Dynamics

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 variable volume ratio screw compressor maintains maximum efficiency by adapting to changing climate conditions, avoiding undercompression and overcompression, thereby reducing energy consumption and noise, while allowing for minimal disassembly and cost-effective procurement based on severe conditions.

Implementation Method 1

The volume ratio is determined by the size and shape of the discharge port, since the groove volume is a fixed volume at the start of compression. The discharge port volume includes a penetration that houses a movable member or plug. The movable plug or member allows the discharge port volume to be varied.

Methodology Applied
Scientific EffectVolume ratio adjustment:

Implementation Method 2

The refrigerant is compressed between the rotors in the interlobe region as the rotors rotate with respect to one another, compressing the refrigerant gas and raising its pressure.

Methodology Applied
Scientific EffectCompression: Compression

Implementation Method 3

The highly compressed gas is ejected from the rotor interlobe region as a high pressure gas, which is expelled into a discharge port in fluid communication with the refrigeration circuit.

Methodology Applied
Scientific EffectFluid flow:

Data Source

PatentEP2758669B1MANUAL Vi ADJUSTMENT MECHANISM FOR SCREW COMPRESSORS
Publication Date: 2015.06.24 JOHNSON CONTROLS TECHNOLOGY CO
  • EP2758669B1 patent drawingFigure 1
  • EP2758669B1 patent drawingFigure 2
  • EP2758669B1 patent drawingFigure 3

AI summary

A variable capacity screw compressor for use in a refrigeration system is provided. Compressed refrigerant gas from the compressor is expelled into a discharge port in fluid communication with the refrigeration circuit. The volume associated with the discharge port can be periodically varied, allowing the efficiency of the compressor to be varied periodically. The discharge port volume includes a penetration that houses a movable member or plug that permits the volume to be periodically varied. This movable member is accessible from the exterior of the compressor housing to adjust the position of the movable member within the discharge port volume. The movable member may be adjusted to a full open position in which the discharge port volume is maximized, to a full closed position in which the discharge port volume is minimized, and to any position between full open and full closed.