Compressor Oil Recirculation for Balanced Refrigeration Lubrication
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Solution Overview
Problem
In refrigeration cycles with multiple compressors of different sizes and variable speeds, existing systems face challenges in maintaining optimal lubrication, leading to damage from either insufficient or excessive oil circulation, particularly when active oil distribution systems are costly and prone to failure.
Innovation Solution
A self-regulating mechanism that enhances oil circulation rate by using features like oil dispersing blades or by-pass lines to increase oil transport when the oil sump level exceeds a nominal value, ensuring balanced oil distribution between compressors without the need for active management systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If multiple compressors of different sizes are used in a refrigeration cycle, then the cooling capacity and versatility of the system is improved, but the oil distribution balance deteriorates causing damage from insufficient or excessive oil circulation
Solution Approach 1:
The system divides the refrigeration load into multiple compressor units of different sizes, each capable of independent operation. This segmentation allows the system to adapt to varying cooling demands while the oil circulation system is designed to serve each compressor independently, preventing oil distribution imbalances that would occur in a shared system.
Solution Approach 2:
Each compressor is equipped with its own dedicated oil circulation system with locally adjusted oil supply parameters. The oil circulation rate, pressure, and flow characteristics are optimized specifically for each compressor's requirements based on its size and operating conditions, ensuring reliable lubrication regardless of the varying capacities of different compressors in the system.
2Use of energy by moving object
If compressors operate at variable speeds, then the energy efficiency and adaptability of the refrigeration system is improved, but the oil circulation rate balance deteriorates causing lubrication failures
Solution Approach 1:
The oil circulation system is designed with dynamic characteristics that match the variable speed operation of compressors. Oil supply mechanisms can automatically adjust flow rates in response to changing compressor speeds, and the system incorporates dynamic pressure compensation to maintain adequate oil delivery across the full operating range, preventing lubrication failures during speed transitions.
Solution Approach 2:
The system incorporates feedback mechanisms that monitor oil circulation rates and compressor operating conditions in real-time. Based on this feedback, the oil supply system automatically adjusts parameters such as flow rate and pressure to maintain optimal lubrication conditions regardless of compressor speed variations, ensuring reliable operation across all operating points.
3Reliability
If active oil distribution systems are used to balance oil distribution, then the oil circulation balance is improved, but the system cost and complexity increase
Solution Approach 1:
The oil circulation system is designed to be self-regulating, using the inherent characteristics of oil flow and compressor operation to automatically balance oil distribution. Each compressor's oil supply is designed to self-adjust based on its own operating conditions, eliminating the need for external active control systems, sensors, or actuators that would increase complexity.
Solution Approach 2:
The system replaces complex active oil distribution control mechanisms with simple, passive oil circulation components that are inexpensive and reliable. Rather than using expensive active control systems with multiple moving parts that could fail, the design employs simple oil supply arrangements that maintain balance through their inherent design characteristics.
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 reduces costs, increases system reliability, and prevents both overfilling and underfilling of oil, allowing for stable operation across varying compressor sizes and speeds, thereby enhancing the overall efficiency and reliability of refrigeration systems.
Implementation Method 1
The suction gas entrainment feature comprises a suction gas entrainment element arranged in the compression element suction line and the oil circulation rate enhancement feature comprises suction gas entrainment means
Implementation Method 2
DE 619 921 shows a compressor in particular for home cooling devices comprising a device for oil separation in which the oil is separated by centrifugal forces
Data Source
Figure 1~3
Figure 4~6
Figure 7~8
AI summary
A compressor (2) for a refrigeration cycle according to the invention comprises an inlet port (6), a compression element (10), an outlet port (18), wherein in operation a refrigerant flow (20) of a gaseous refrigerant carrying an amount of oil circulates through the inlet port (6), the compression element (10) and the outlet port (18), and an oil sump (8) in which part of the oil carried by the gaseous refrigerant collects. An oil circulation rate enhancement feature (16) is provided being configured so as to direct oil from the oil sump (8) to the refrigerant flow (20), when the oil in the oil sump (8) exceeds a predetermined oil sump level (24).