Composite Valve Pilot Switching for Precise Dual-Range Flow Control
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Solution Overview
Problem
Existing composite valves for heat pump systems face challenges in achieving precise flow rate control in both small and large flow rate regions while minimizing pressure loss and electric power consumption, often requiring larger sizes and increased costs due to conflicting demands for high precision and low resistance.
Innovation Solution
A composite valve design featuring a pilot type first control valve for large flow rates and a second control valve for small flow rates, with orthogonal valve body arrangements and a communication path structure that optimizes the dimensions and shapes for each flow rate, preventing undesired opening and reducing spring load requirements, thus enhancing precision and reducing size and power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single electrically operated valve is used to control both cooling and heating functions, then the system size is reduced and cost is lowered, but it becomes difficult to achieve high precision flow rate control in both small and large flow rate regions simultaneously
Solution Approach 1:
The valve is divided into two independent control mechanisms: a first control valve for large flow rates and a second control valve for small flow rates. This segmentation allows each valve to be optimized for its specific flow range, achieving high precision control in both regions while maintaining a compact single-valve structure.
Solution Approach 2:
The valve employs dynamic switching between two control modes based on flow rate requirements. The first control valve operates during high flow rate conditions (cooling mode), while the second control valve takes over during low flow rate conditions (heating mode), allowing the system to adapt to different operational requirements seamlessly.
2Measurement precision
If the valve bore diameter is made small to improve flow rate control precision in the small flow rate region, then control precision is improved, but the controllable flow rate is reduced and pressure loss is enlarged
Solution Approach 1:
The valve bore is segmented into two distinct pathways: a smaller second valve bore for precise small flow rate control and a larger first valve bore for high flow rate passage. This eliminates the need to compromise the small bore dimensions for large flow capacity, as each serves its intended purpose optimally.
Solution Approach 2:
The valve structure incorporates vertical stacking of control mechanisms, with the first control valve positioned above the second control valve. This three-dimensional arrangement allows both small and large bore diameters to coexist within a compact valve body, resolving the dimensional conflict between precision control and high flow capacity.
3Productivity
If the valve bore diameter is made large to increase controllable flow rate and reduce pressure loss, then flow rate and efficiency are improved, but the flow rate control precision in the small flow rate region is lowered
Solution Approach 1:
The valve incorporates two separate control pathways with different bore diameters: a large first valve bore for high flow rate applications and a small second valve bore for precise low flow rate control. This segmentation allows the system to achieve both high productivity and high precision by selecting the appropriate control pathway based on operational requirements.
4Reliability
If a valve closing spring with large spring load is used to prevent undesired opening of the second valve, then reliability is improved, but the valve size and electric power consumption are enlarged
Solution Approach 1:
The valve utilizes refrigerant pressure differential to assist valve closing. High pressure refrigerant from the first valve chamber is introduced into the second valve chamber, creating a pressure differential that generates a closing force on the second valve body. This hydraulic assistance reduces the spring load requirement while maintaining reliable valve closure.
5Reliability
If the second valve port bore diameter is constrained by large spring load requirements, then valve closed state stability is maintained, but the flow rate control precision and controllable flow rate are reduced
Solution Approach 1:
The hydraulic pressure differential mechanism allows the second valve port to maintain a larger bore diameter for high precision control while the refrigerant pressure provides the additional closing force needed to prevent undesired opening. This eliminates the need for oversized springs that would constrain the valve port dimensions.
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 design achieves improved flow rate control precision in the small flow rate region, increased controllable flow rates, reduced pressure loss, and lower electric power consumption without enlarging the valve size or increasing motion load, thereby addressing the limitations of previous solutions.
Implementation Method 1
the high pressure in the first valve chamber is introduced into the second valve chamber, a valve closing force acting on the second valve body in the valve closing state becomes significantly larger than a force which is going to push up it
Implementation Method 2
A composite valve design featuring a pilot type first control valve for large flow rates and a second control valve for small flow rates, with orthogonal valve body arrangements and a communication path structure that optimizes the dimensions and shapes for each flow rate, preventing undesired opening and reducing spring load requirements, thus enhancing precision and reducing size and power consumption
Data Source
AI summary
A composite valve has a communication path communicating a first valve chamber with a second valve chamber, a second valve port communicating the second valve chamber with an outflow port, and a pilot passage communicating a back pressure chamber with the outflow port. In the case that a lift amount of a second valve body for a small flow rate control is equal to or less than a predetermined amount, the pilot passage is closed by a pilot valve body, and a first valve port is closed by a first valve body, thereby taking a small flow rate control state. In the case that the lift amount of the second valve body goes beyond the predetermined amount, the pilot valve body is moved up in conjunction with the upward movement of a valve shaft so as to open the pilot passage, thereby taking a large flow rate control state.