Compressor Frequency Control for Oil Recovery During Heating
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Solution Overview
Problem
In air conditioners, refrigeration machine oil can accumulate in the refrigerant circuit during compressor operation, leading to poor lubrication and potential burnout, and existing methods to recover this oil impair the heating capacity by requiring a switch to a cooling cycle.
Innovation Solution
An air conditioner system with oil amount calculation means and frequency control means to increase compressor operating frequency during heating when oil accumulation is detected, allowing oil recovery without switching to a cooling cycle, and includes pressure detection and switching mechanisms to manage refrigerant pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the air conditioner is switched to a cooling cycle to recover refrigerating machine oil, then the oil can be blended into liquid refrigerant and recovered to the compressor, but the heating capacity is significantly impaired
Solution Approach 1:
The invention changes the operating parameters of the compressor during heating operation by adjusting the discharge pressure to a predetermined value or higher. This parameter change enables oil recovery while maintaining the heating cycle, eliminating the need to switch to cooling mode and thus preserving heating capacity while still achieving reliable oil recovery
Solution Approach 2:
The invention dynamically adjusts the compressor's discharge pressure based on operating conditions. By controlling the discharge pressure to be at or above a predetermined value during heating operation, the system adaptively achieves oil recovery conditions without fixed cycle switching, maintaining both heating function and lubrication reliability
2Productivity
If the compressor operates at normal frequency during heating, then heating efficiency is maintained, but refrigerating machine oil accumulates in the refrigerant circuit causing poor lubrication
Solution Approach 1:
The invention implements a feedback control mechanism where the discharge pressure of the compressor is monitored and adjusted to maintain a predetermined value or higher during heating operation. This feedback loop ensures that oil recovery conditions are met while maintaining heating efficiency, preventing oil accumulation without sacrificing productivity
Solution Approach 2:
The invention modifies the discharge pressure parameter during heating operation to enable oil recovery. By maintaining discharge pressure at or above a predetermined value, the system creates conditions for oil to return to the compressor while continuing normal heating operation, thus preserving both heating efficiency and lubrication 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
Enables recovery of refrigeration machine oil without reducing heating capacity, preventing compressor burnout and maintaining system efficiency by forced circulation and pressure management.
Implementation Method 1
the compressor (21) is controlled to increase the operating frequency so that the refrigerating machine oil accumulating in a pipe of the refrigerant circuit (R) can be forcedly circulated through the refrigerant circuit (R) and recovered to the compressor (21)
Implementation Method 2
pressure detection means (Ps1) configured to detect the high-side pressure of refrigerant flowing through the refrigerant circuit (R)
Implementation Method 3
the switching mechanism (30A) includes a first control valve (31) for selectively permitting or shutting off the flow of refrigerant into the high-pressure gas pipe (11), and a second control valve (32) for selectively permitting or shutting off the flow of refrigerant into the low-pressure gas pipe (12), and is configured to provide communication between the high-pressure gas pipe (11) and the low-pressure gas pipe (12) by opening the second control valve (32) when the value detected by the pressure detection means (Ps1) is equal to or above a predetermined value
Data Source
AI summary
When during a heating operation the value calculated by an oil amount calculation section (51) is equal to or above a predetermined value, a frequency control section (52) of a controller (50) increases the operating frequency of a compressor (21) in order to recover refrigerating machine oil in a refrigerant circuit (R).