Compressor Discharge Valve for Oil Return and Freeze Protection
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Solution Overview
Problem
Existing refrigerant compressor discharge valves suffer from issues such as inadequate lubrication at startup, potential freezing of evaporators during low ambient temperatures, and chatter due to fluctuating discharge pressures, which are not effectively addressed by existing solutions like the Pillis and Heitmann valves.
Innovation Solution
A discharge valve with a valve plug that moves between closed and open positions in response to pressure differentials, featuring a spring-urged valve plug, a stem guide for fluid passageway, and a pivotally attached valve stem to ensure controlled opening and prevent chatter, while minimizing flow restriction and promoting oil return.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the discharge valve opens quickly to minimize flow restriction, then refrigerant flow increases, but discharge pressure fluctuates causing valve chatter
Solution Approach 1:
The valve stem is made movable relative to the valve plug, allowing the valve stem to move axially in response to pressure differentials. This dynamic adjustment enables the valve to open smoothly without chatter while maintaining adequate refrigerant flow, resolving the contradiction between productivity and reliability.
2Stress or pressure
If the discharge valve is restricted to increase discharge pressure for oil return, then oil return improves, but valve chatter occurs during opening
Solution Approach 1:
The movable valve stem allows progressive opening of the valve as discharge pressure builds, preventing chatter while maintaining sufficient pressure for oil return. The valve stem moves in response to the pressure differential between discharge and suction sides, providing a dynamic balance between pressure buildup and flow restriction.
Solution Approach 2:
The valve stem acts as an intermediary element between the valve plug and the actuating forces. Its movable connection allows it to mediate the opening process, enabling smooth valve operation that prevents chatter while maintaining the pressure restriction needed for oil return.
3Object-affected harmful factors
If the valve plug is held closed to prevent evaporator freezing, then freeze protection improves, but oil return is compromised
Solution Approach 1:
The dynamic valve stem allows the valve to respond automatically to system conditions. When discharge pressure is sufficient for oil return, the valve opens to prevent evaporator freezing. When pressure is low, the valve remains closed to maintain pressure for oil return, dynamically balancing freeze protection and oil return reliability.
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
The solution ensures proper oil return to the compressor, prevents evaporator freezing, and reduces chatter by maintaining a stable discharge pressure, thereby ensuring efficient operation and preventing rotor rubbing against the compressor housing.
Implementation Method 1
The discharge valve also comprises a spring disposed within one of the piston chamber and the discharge chamber to urge the valve plug toward the valve seat
Implementation Method 2
The valve plug moves to the closed position in response to the pressure differential between the high-pressure side and the low-pressure side being below a predetermined limit. The valve plug moves toward the open position in response to the pressure differential between the high-pressure side and the low-pressure side being at least as great as the predetermined limit
Data Source
AI summary
A refrigerant system includes a compressor with a discharge valve that temporarily restricts the compressor's outflow at startup so that the discharge pressure can quickly rise to force lubricant back to the compressor. The discharge valve also helps prevent an axial face of a rotor of a screw compressor from rubbing against a bearing housing axial face of the compressor's housing. When the system turns off under certain low ambient air temperature conditions, the valve closes to help prevent the system's evaporator from freezing up. The discharge valve includes a novel arrangement of a piston, a valve stem extending from the piston, and a valve plug pivotally attached to the valve stem. The pivotal connection ensures a positive seal between the valve plug and a valve seat. A somewhat restricted fluid passageway between the valve's discharge chamber and piston chamber helps prevent the valve from chattering as the valve opens.