Expansion Valve Assembly for Reversible Refrigerant Flow
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Solution Overview
Problem
In heat pump type refrigeration cycle apparatuses, the placement of a single expansion valve is problematic as it leads to pressure loss and difficulty in flow rate control, especially when the refrigerant flow is reversed, necessitating the use of two expansion valves, which complicates routing refrigerant flow through the system when one valve is non-controlling.
Innovation Solution
A refrigerant expansion valve arrangement with a pilot operated main spool valve, a pilot valve, a feedback valve, and a check valve that allows the valve to fully open when non-controlling, permitting reverse flow and optimizing the balance of forces to ensure efficient operation in both heating and cooling modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single expansion valve is used in heat pump type refrigeration cycle apparatuses, then the device complexity is reduced, but pressure loss increases and flow rate control becomes difficult when refrigerant flow is reversed
Solution Approach 1:
The expansion valve is designed with a pilot operated main spool valve that can dynamically change its flow characteristics. The valve transitions between a throttling position (when controlling flow) and a fully open position (when non-controlling), allowing the system to adapt to different operational modes (heating/cooling) and minimize pressure loss in reverse flow conditions
2Device complexity
If a single expansion valve is used, then the device complexity is reduced, but flow rate control precision deteriorates when the valve is non-controlling
Solution Approach 1:
The valve utilizes a pilot operated main spool valve that can dynamically position itself. When non-controlling, the valve fully opens to permit unrestricted flow, eliminating flow control issues. When controlling, it transitions to a throttling position with precise flow control capability, thus maintaining measurement precision across different operational states
Solution Approach 2:
The single expansion valve is designed to perform multiple functions: it can control refrigerant flow in one direction while fully opening to permit unrestricted flow in the reverse direction. This multi-functionality allows one valve to replace what would traditionally require two valves, maintaining flow rate control precision in both heating and cooling modes
3Measurement precision
If two expansion valves are used to handle reversed refrigerant flow, then flow rate control precision is maintained in both directions, but the device complexity and routing complexity increase
Solution Approach 1:
The invention makes a single expansion valve universal by enabling it to handle both controlling and non-controlling scenarios. The pilot operated main spool valve can fully open to permit unrestricted reverse flow while maintaining the ability to throttle when needed, thus one valve performs the work of two valves without increasing device complexity
Solution Approach 2:
The dynamic positioning capability of the pilot operated main spool valve allows it to adapt its flow characteristics based on operational requirements. This dynamic behavior enables a single valve to maintain flow rate control precision in both heating and cooling modes, replacing the need for two static valves
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 solution enables efficient control of refrigerant flow in both heating and cooling modes by ensuring the expansion valve is fully open when non-controlling, thereby optimizing system performance and reducing pressure losses, even when the valve is not directly controlling the flow.
Implementation Method 1
a control element positionable to one or more throttled positions for controlling fluid flow through the first fluid passageway from the first port to the second port, and positionable to a fully open position to permit free flow from the second port to the first port
Implementation Method 2
a check valve in the second fluid passageway prevents fluid flow from the first port to the second port, and permits fluid flow through to the first port from the second port to the first port
Implementation Method 3
optimizing the balance of forces to ensure efficient operation in both heating and cooling modes
Data Source
AI summary
An arrangement includes a housing defining a first and second ports. A first passageway provides communication between the ports; a second passageway provides communication with the first port. An element is disposed in the housing and positioned by a balance of forces, the element is positionable to throttled positions for controlling flow through the first passageway in a first direction and to an open position to permit unrestricted flow in a second direction. A check valve is disposed in the second passageway for preventing flow therein from the first port when pressure in the first port is greater than pressure in the second port, and permitting flow through the second passageway to the first port when pressure in the first port is less than the pressure in the second port thereby affecting the balance of forces acting on the element so the element is urged toward the fully open position.