Refrigeration Cycle Valve Control for Multi-Mode Oil Circulation
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Solution Overview
Problem
Vapor compression type refrigeration cycle devices for vehicular air conditioners have complex configurations and control modes due to the need to adjust refrigerant states for different operation modes, leading to complications in switching between cooling, heating, and dehumidification modes, particularly in managing refrigerant flow and oil stagnation.
Innovation Solution
A refrigeration cycle device with a compressor, heat exchanger, branch passage, cooling and heat absorption valves, and a circuit switching valve that adjusts the refrigerant state to a gas-liquid two-phase state when switching between operation modes, allowing for simple configuration changes without complicating the cycle configuration, and includes an internal heat exchanger to improve the coefficient of performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the refrigeration cycle device switches between cooling, heating, and dehumidification modes using conventional methods, then different refrigerant circuits are activated, but the configuration becomes complex and control modes become complicated
Solution Approach 1:
The patent applies multi-functionality by enabling a single refrigerant circuit configuration to serve multiple operation modes (cooling, heating, dehumidification) through strategic placement of the four-way valve and expansion valves. The circuit is designed so that the same physical components can be activated in different sequences and configurations to achieve different thermal functions, eliminating the need for separate dedicated circuits for each mode.
Solution Approach 2:
The patent employs dynamic control through electronic expansion valves and four-way valves that can adjust their opening degrees and positions based on real-time operational requirements. The control unit dynamically switches between modes by adjusting valve positions and refrigerant flow directions, allowing the system to adapt its configuration without physical reconfiguration, thus maintaining simplicity while achieving versatility.
2Productivity
If the refrigerant flow is adjusted for different operation modes, then the refrigeration performance is optimized, but oil stagnation problems occur in the evaporators
Solution Approach 1:
The patent changes refrigerant flow parameters (pressure, temperature, flow rate) dynamically through electronic expansion valves to optimize refrigeration performance in each mode. By precisely controlling the degree of opening of expansion valves, the system adjusts refrigerant parameters to match operational requirements while maintaining sufficient flow velocity to prevent oil stagnation in evaporators.
Solution Approach 2:
The system incorporates feedback control through the control unit that monitors operational conditions and adjusts valve positions accordingly. This feedback mechanism ensures that refrigerant flow is optimized for performance while simultaneously preventing oil stagnation by maintaining appropriate flow rates, thus resolving the contradiction between productivity and reliability.
3Adaptability or versatility
If multiple expansion valves are used to control refrigerant flow in different circuits, then mode switching is enabled, but the device configuration becomes more complex
Solution Approach 1:
The patent merges the functions of multiple expansion valves into a unified control system where two electronic expansion valves work in coordination within a single refrigerant circuit. Rather than having separate expansion valves for each mode, the system combines their functions and uses a control unit to manage their operation, reducing overall system complexity while maintaining operational flexibility.
Solution Approach 2:
The electronic expansion valves are designed to perform multiple functions across different operation modes. The same valves used for cooling mode refrigerant expansion are also utilized in heating and dehumidification modes, eliminating the need for mode-specific valves and thereby reducing device complexity while preserving operational versatility.
4Adaptability or versatility
If the refrigerant is throttled to achieve evaporation in different modes, then the cooling and heating effects are achieved, but the coefficient of performance decreases
Solution Approach 1:
The patent optimizes the coefficient of performance by dynamically changing refrigerant parameters (pressure, temperature, flow rate) through electronic expansion valves. By precisely controlling the degree of opening, the system minimizes unnecessary throttling losses and ensures efficient heat exchange in both cooling and heating modes, thereby maintaining high COP across different operation modes.
Solution Approach 2:
The system employs a composite approach by integrating multiple valve types (four-way valve, electronic expansion valves) and heat exchangers into a unified refrigerant circuit. This composite configuration allows efficient heat transfer and minimal energy loss by optimizing the interaction between different components, thereby maintaining high coefficient of performance across multiple operation modes.
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 efficient switching between operation modes without complicating the cycle configuration, reduces refrigerant oil stagnation, and improves the coefficient of performance by appropriately adjusting refrigerant states and enthalpy in the refrigeration cycle device.
Implementation Method 1
a compressor that compresses and discharges a refrigerant mixed with a refrigerator oil
Implementation Method 2
a heat exchanger that heats a ventilation air by using a heat of the refrigerant discharged from the compressor as a heat source
Implementation Method 3
a cooling valve that reduces a pressure of the refrigerant flowing out from one refrigerant outflow port of the branch passage
Implementation Method 4
a cooling evaporator that evaporates the refrigerant by heat exchange between the refrigerant reduced in pressure by the cooling valve and the ventilation air
Data Source
AI summary
In a refrigeration cycle device, in an operation mode in which a refrigerant does not flows into a cooling evaporator, a throttle opening degree characteristic of a heat absorption valve disposed upstream of a heat absorption evaporator is set to cause the refrigerant on the outlet side of the heat absorption evaporator to be in a gas-liquid two-phase state.