Multi-Split Air Conditioner Oil Return During Heating
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Solution Overview
Problem
In multi-split air conditioners during heating, oil accumulation in gas pipes leads to insufficient lubrication in the compressor, causing operational issues and discomfort due to inefficient oil return methods that disrupt heating performance.
Innovation Solution
Adjusting the compressor operation frequency and indoor throttling element open degrees to maintain refrigerant flow velocity and ensure oil return without switching the four-way valve, while monitoring and adjusting parameters to maintain optimal pressure and temperature conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the four-way valve is switched to refrigeration mode for oil return, then oil can be returned effectively, but heating operation stops and the air conditioner remains in low pressure state for a period of time
Solution Approach 1:
The patent changes the operating parameters of the system by adjusting compressor frequency and throttling element openings instead of switching the four-way valve. The compressor frequency is adjusted to a first preset frequency and then a second preset frequency, while indoor throttling elements are adjusted to preset openings, enabling oil return while maintaining heating mode and high pressure state
Solution Approach 2:
The patent dynamically adjusts the operation frequency of the compressor and the opening degree of throttling elements during the oil return process. The compressor frequency is first adjusted to a first preset frequency, then to a second preset frequency that is higher than the first, allowing the system to adapt to different stages of oil return while maintaining heating operation
2Productivity
If the compressor operation frequency is increased and throttling element steps are increased for oil return, then heating comfort is maintained, but the running of the air conditioner is more greatly affected
Solution Approach 1:
The patent implements a periodic oil return process by first adjusting the compressor to a first preset frequency for an initial period, then after a first period of time, adjusting to a second preset frequency for a subsequent period. This periodic adjustment enables oil return while maintaining system stability and heating comfort
Solution Approach 2:
The patent monitors the high pressure value during the oil return process and compares it with a preset high pressure. Based on this feedback, the system determines whether to continue the oil return process or adjust parameters, ensuring reliable oil return while maintaining system stability
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 ensures reliable oil return, maintains heating efficiency, and improves user comfort by preventing compressor damage and ensuring consistent operation during the oil return process.
Implementation Method 1
adjusting the operation frequency of the compressor
Implementation Method 2
adjusting the open degree of the indoor throttling element of each indoor unit
Implementation Method 3
the indoor unit acts as an evaporator
Implementation Method 4
switching the four-way valve to the refrigeration mode
Data Source
Figure 1
Figure 2
AI summary
An oil return method for multi-split air conditioner in heating comprises steps of: S1, adjusting operation frequency f0 of a compressor (11) to a first preset oil return frequency f1, and simultaneously, adjusting open degree S0 of each indoor throttling element (22) to a preset oil return open degree; S2, measuring operation parameters of the air conditioner; S3, judging whether the air conditioner operates abnormally, jumping to Step S4 if so, or jumping to Step S5 if not; S4, exiting from oil return process, adjusting the operation frequency f0 of the compressor (11) to a second preset oil return frequency f1, judging whether the air conditioner operates abnormally, existing from the oil return process if so, or jumping to Step S5 if not; S5, ending the oil return process when oil return time reaches the oil return time t2.