Refrigerant Charging Flow Control for Stable Fill Time
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Solution Overview
Problem
Conventional refrigerant charging devices experience variations in charging speed due to pressure differences, leading to longer charging times, especially when outdoor air temperature drops.
Innovation Solution
A refrigerant charging device with a flow rate control unit that adjusts the electric valve's opening based on the pressure difference between the saturation pressure corresponding to outdoor air temperature and the refrigerant pressure on the suction side, maintaining a consistent refrigerant flow rate through the supply pipe, and a correction control unit to manage superheat and prevent refrigerant wetness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If refrigerant charging relies on pressure difference between cylinder and suction side, then charging process is simple, but charging speed varies and increases charging time
Solution Approach 1:
The patent applies the dynamics principle by making the valve opening degree adjustable and variable during the charging process. The valve opening degree is dynamically changed based on detected refrigerant pressure and temperature to maintain substantially constant charging speed, resolving the contradiction between simple charging process and variable charging speed.
Solution Approach 2:
The patent applies parameter changes by modifying the valve opening degree as a controllable parameter in response to changes in refrigerant pressure and temperature. This allows the system to adapt to varying pressure differences and maintain stable charging speed, addressing the issue of charging time variation.
2Productivity
If valve opening is increased to maintain flow rate, then refrigerant charging speed is improved, but refrigerant wetness may occur causing compressor damage
Solution Approach 1:
The patent applies feedback by using a detector to continuously monitor refrigerant pressure and temperature, then using this information to adjust the valve opening degree. This closed-loop control ensures that the refrigerant evaporates completely before entering the compressor, preventing wetness while maintaining efficient charging speed.
Solution Approach 2:
The patent applies preliminary action by ensuring the refrigerant is fully evaporated in the evaporator before reaching the compressor. This preliminary evaporation step prevents wet refrigerant from entering the compressor, thereby protecting the compressor while allowing faster charging.
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 stabilizes the refrigerant flow rate and prevents prolonged charging times by adjusting the valve opening to maintain a predetermined flow rate and superheat, ensuring efficient refrigerant charging while preventing compressor damage from wet refrigerant.
Implementation Method 1
the refrigerant flows through the supply pipe into the refrigerant circuit, to be charged into the latter, in accordance with the pressure difference between the refrigerant pressure in the cylinder and the pressure in the suction side of the compression mechanism
Implementation Method 2
a heat exchanger for heat exchange between the refrigerant and outdoor air
Implementation Method 3
a compression mechanism for compressing the refrigerant
Data Source
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AI summary
Suppression of variation in the charging time of refrigerant into a refrigerant circuit is enabled. A refrigerant charging device includes: an electric valve (49) provided in a supply pipe (47); a flow rate control unit (50) for controlling the degree of opening of the electric valve (49) such that the flow rate in the supply pipe (47) lies within a predetermined range, on the basis of a pressure difference between pressure of refrigerant supplied to the supply pipe (47) and the pressure of refrigerant on the suction side of a compressor (14); an outdoor air temperature sensor (36) for detecting outdoor air temperature; and a low-pressure side pressure sensor (34) for detecting refrigerant pressure on the suction side of the compressor (14). The pressure difference is a difference between a saturation pressure corresponding to the outdoor air temperature detected by the outdoor air temperature sensor (36) and refrigerant pressure detected by the low-pressure side pressure sensor (34).