Oil sump for multi-compressor HVAC and R system
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Solution Overview
Problem
HVAC&R systems with multiple compressors face challenges in equal oil distribution due to mixed compressor configurations and operational conditions, leading to insufficient oil levels, which existing solutions like oil line connections and pressure regulators do not reliably address across all configurations and conditions.
Innovation Solution
A lubricant sump with pressure greater than compressor cavity pressures, connected via an equilibrium lubricant line to ensure consistent lubricant distribution to each compressor, maintaining a minimum oil level and equalizing suction line pressure, with optional pressure equalizer lines to stabilize oil distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If oil line connections and pressure regulators are used to distribute oil to compressors, then oil distribution can be controlled, but the system becomes complex and unreliable across mixed compressor configurations and operational conditions
Solution Approach 1:
The patent extracts the oil distribution control function from complex active components (pressure regulators, flow controllers) and replaces it with a passive pressure-driven system. The oil sump is positioned at a higher elevation than compressor oil cavities, creating gravitational pressure that automatically distributes oil to all compressors without requiring active control mechanisms, thereby reducing system complexity while maintaining reliability.
Solution Approach 2:
The patent creates an equipotential oil distribution system by positioning the oil sump at a strategic elevation and using pressure equalizer lines to balance pressure across all compressor oil cavities. This ensures that oil pressure is effectively equalized throughout the system, allowing reliable oil distribution to compressors of mixed configurations without requiring individual pressure control for each compressor.
2Adaptability or versatility
If compressors are arranged in fluidly parallel configuration with mixed configurations, then system capacity control and efficiency are improved, but oil distribution becomes uneven and unreliable
Solution Approach 1:
The patent uses pressure equalizer lines connecting the oil sump to each compressor oil cavity to equalize pressure across all compressors regardless of their size or operational status. This passive pressure equalization system ensures that oil distributes reliably to all compressors in the parallel configuration, accommodating mixed compressor sizes and fixed/variable speed configurations without compromising oil level sufficiency.
Solution Approach 2:
The oil distribution system operates autonomously using the pressure differential created by the elevated oil sump position. Oil automatically flows from the sump to compressor oil cavities and returns to the sump, creating a self-regulating system that adapts to varying compressor operational conditions without requiring external control, thereby maintaining reliability across diverse compressor configurations.
3Reliability
If pressure drop regulators are installed at compressor suction ports to reduce oil level differences, then oil distribution can be controlled, but device complexity increases and reliability across all conditions is not ensured
Solution Approach 1:
The patent removes pressure drop regulators from the suction line system and replaces them with an elevated oil sump that uses gravitational pressure to balance oil levels in compressor cavities. This eliminates the need for active pressure control devices in the suction line while achieving the same oil level balancing function through passive gravitational pressure, thereby reducing device complexity while maintaining reliability.
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 solution ensures reliable and efficient oil management across various compressor configurations and operational conditions, maintaining adequate lubrication levels and system performance.
Implementation Method 1
A lubricant sump pressure is greater than a lubricant cavity pressure of each compressor of the two or more compressors at all operating conditions of the two or more compressors
Implementation Method 2
An equilibrium lubricant line connects the lubricant sump to the two or more compressors to convey lubricant from the lubricant sump to a lubricant cavity of each compressor
Data Source
AI summary
A compressor arrangement includes two or more compressors (16a, 16b) arranged in a fluidly parallel configuration and a lubricant sump (38) containing a volume of lubricant operably connected to the two or more compressors. A lubricant sump pressure (P) is greater than a lubricant cavity pressure of each compressor (Pa, Pb, Pc) of the two or more compressors at all operating conditions of the two or more compressors. An equilibrium lubricant line (40) connects the lubricant sump to the two or more compressors to convey lubricant from the lubricant sump to a lubricant cavity (42) of each compressor of the two or more compressors.