Multi-Split Expansion Valve Cyclic Control to Reduce Refrigerant Noise
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Solution Overview
Problem
In multi-split systems, the noise generated by refrigerant flowing through expansion valves during heating mode can significantly affect user experience, especially when indoor units are in a non-working state, as the refrigerant may be in a gas-liquid two-phase state, leading to excessive noise.
Innovation Solution
A method and device that control the expansion valves by turning off all indoor units in a non-working state and adjusting the compressor's working frequency based on the number of inactive units, while selectively turning on expansion valves in a predetermined cycle to minimize noise and maintain system pressure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the expansion valve is opened during heating mode, then refrigerant flow is maintained for system operation, but large noise is generated when indoor units are shut down
Solution Approach 1:
The patent implements periodic action by controlling expansion valves to open and close in a predetermined cycle rather than remaining constantly open. The controller opens expansion valves for indoor units in a sequential manner over time, allowing refrigerant flow to be maintained periodically while preventing continuous noise generation during shutdown periods. This temporal segmentation of valve operation resolves the contradiction between maintaining system operation and reducing noise.
2Object-generated harmful factors
If all expansion valves are closed to eliminate noise, then noise is reduced, but system pressure may be compromised
Solution Approach 1:
The patent applies partial action by opening only a specified number of expansion valves rather than all valves, and doing so in a predetermined cycle rather than continuously. This partial opening maintains sufficient refrigerant flow to preserve system pressure and reliability while limiting the number of active valves at any given time to reduce overall noise levels. The controller selectively activates valves based on system needs rather than maintaining full operation.
3Object-generated harmful factors
If expansion valves are opened in a predetermined cycle, then noise is minimized, but control complexity increases
Solution Approach 1:
The patent segments the control of multiple expansion valves into discrete, individually controllable units. Each expansion valve is controlled separately by the controller based on a predetermined cycle, allowing the system to manage noise by activating only specific valves at specific times. This segmentation enables simplified control logic where each valve follows the same periodic pattern, reducing overall control complexity compared to managing all valves simultaneously.
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 noise interference by allowing only a portion of indoor units to generate noise, effectively minimizing disruptions and maintaining system safety and operation.
Implementation Method 1
then enters an outdoor unit through an electronic expansion valve, evaporates into a low-temperature gaseous refrigerant at the outdoor unit heat exchanger after throttling and depressurizing
Implementation Method 2
a high-temperature and high-pressure gaseous refrigerant output by a compressor is condensed into a high-pressure normal-temperature liquid refrigerant in the indoor unit heat exchanger
Implementation Method 3
and is compressed into a high-temperature and high-pressure gaseous refrigerant through the compressor to complete a cycle of a refrigeration system
Data Source
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Figure 5~7
AI summary
The present disclosure discloses a method and a device for controlling an expansion valve. The method includes: when a first specified number of indoor units are in a non-working state, turning off (101) expansion valves corresponding to all the indoor units in the non-working state; and turning on (102) expansion valves corresponding to a second specified number of indoor units in the non-working state in turn according to a predetermined cycle.