Parallel Compressor Climate Control Without Oil Equalization
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Solution Overview
Problem
Conventional climate systems with parallel compressors face challenges in efficiently managing compressor oil distribution without an oil equalization system, leading to uneven lubrication and reduced efficiency, and are often complex and costly to maintain.
Innovation Solution
A climate system with parallel compressors that uses a controller to independently manage compressor oil distribution by operating compressors at low speed ranges before shutdown to draw back oil, eliminating the need for an oil equalization system and allowing for compressors of different sizes and configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an oil equalization line system is used to connect compressor crankcases, then oil distribution between compressors is improved, but device complexity and cost increase
Solution Approach 1:
The patent removes the oil equalization line system entirely from the parallel compressor configuration. Instead of adding complex equalization lines between compressors, the invention extracts this component and relies on each compressor's independent oil sump and refrigerant circuit to manage its own oil requirements, thereby reducing device complexity while maintaining reliable oil distribution
Solution Approach 2:
The patent segments the oil management system by providing each compressor with its own independent oil sump and refrigerant circuit. This segmentation eliminates the need for inter-compressor oil equalization lines, allowing each compressor to independently manage its oil supply while maintaining reliable lubrication
2Reliability
If oil separators are used to separate and return oil to compressors, then oil distribution is improved, but device complexity and maintenance difficulty increase
Solution Approach 1:
The patent extracts and removes oil separators from the system configuration. Instead of incorporating oil separators that would need to be installed, maintained, and serviced, the invention relies on the natural refrigerant flow and compressor operation to return oil to the oil sumps, eliminating maintenance complexity
3Device complexity
If compressors are arranged in parallel with independent oil sumps, then system simplicity is improved, but oil drawback to compressors becomes problematic
Solution Approach 1:
The patent applies preliminary action by controlling the expansion valve to allow liquid refrigerant to pass through to the evaporator before the compressor shuts off. This preliminary refrigerant flow ensures that oil is carried back to the compressor and oil sump during the brief period before shutdown, solving the oil drawback problem while maintaining system simplicity
Solution Approach 2:
The patent implements feedback control through the controller that monitors compressor operation and coordinates the expansion valve and compressor shutdown timing. This feedback mechanism ensures oil is properly returned to the compressor by adjusting refrigerant flow based on compressor state, maintaining reliable oil return without adding mechanical complexity
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 approach simplifies the system, reduces costs, and enhances efficiency by allowing for flexible installation and independent compressor control based on thermal loads, improving overall reliability and performance.
Implementation Method 1
the controller is electrically coupled to the first and second compressors and configured to automatically and independently control operation of the first and second compressors to draw back compressor oil to the first and second compressors
Data Source
AI summary
Disclosed are climate systems and methods for control the climate systems. A climate system includes a plurality of compressors arranged in parallel, a condenser disposed downstream of the compressors and an evaporator disposed downstream of the condenser. The compressors, the condenser, and the evaporator are fluidly connected by refrigerant lines to form a refrigerant circuit. The climate system also includes a controller that controls the operation of the compressors to draw back lubricant to the compressors without use of an oil equalization system.