Composite Valve Pilot Control for Precise Low-Flow Regulation
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Solution Overview
Problem
Existing composite valves for heat pump systems face challenges in achieving precise flow rate control in small flow rate regions while minimizing pressure loss and reducing electric power consumption, often requiring large spring loads and increased size, which complicates the design and increases costs.
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, where the second valve body is driven by an elevating motion, and a pilot valve is energized downward by a spring member, with a catch mechanism to prevent undesired opening, and a pressure equalizing hole to manage high pressures, allowing for optimal dimensioning and reduced spring loads.
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 the flow rate control precision in small flow rate regions deteriorates and pressure loss increases
Solution Approach 1:
The valve is segmented into two independent control valves: a first control valve with a large valve bore for cooling operation and a second control valve with a small valve bore for heating operation. Each valve has its own valve body and control mechanism, allowing optimized flow rate control for各自的 operating conditions without compromise
Solution Approach 2:
Each control valve is designed with locally optimized characteristics: the first valve has a large bore suitable for high flow rates during cooling, while the second valve has a small bore suitable for precise low flow rate control during heating. This local optimization ensures both valves operate at their best performance in their respective flow rate regions
2Loss of energy
If the valve bore diameter is increased to reduce pressure loss and increase controllable flow rate, then the flow rate control precision in small flow rate regions deteriorates
Solution Approach 1:
The flow control function is segmented into two independent valves with different bore sizes. The first valve handles high flow rates with minimal pressure loss during cooling, while the second valve provides precise control at low flow rates during heating, eliminating the need to compromise valve bore size
3Reliability
If the spring load is increased to prevent undesired valve opening, then the electric power consumption and device size increase
Solution Approach 1:
The sealing function is segmented between two valves, each with appropriately sized spring loads for their specific functions. The second valve's smaller bore allows it to maintain reliable sealing with a smaller spring load, reducing the torque required by the elevation driving mechanism and thereby reducing electric power consumption
Solution Approach 2:
The pilot valve acts as an intermediary mechanism that uses the elevating motion of the valve shaft to control the opening and closing of the first valve. This pilot control mechanism allows the main valve to be opened and closed with reduced direct actuation force, lowering the spring load requirements and associated power consumption
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 design enhances flow rate control precision in small flow rate regions, increases controllable flow rates, reduces pressure loss, and minimizes electric power consumption by preventing undesired valve openings and optimizing valve dimensions, thus achieving cost reduction and downsizing.
Implementation Method 1
a pilot valve body which is driven so as to be opened and closed by utilizing an elevating motion of the valve shaft, wherein the pilot valve is energized downward by a spring member
Implementation Method 2
a pressure equalizing hole to manage high pressures
Data Source
AI summary
A composite valve has a communication path, a second valve port and a pilot passage. First and second valve bodies are arranged to be moved up and down in the same direction, and are away from each other only at a predetermined distance. In the case that a lift amount of the second valve body for a small flow rate control is equal to or less than a predetermined amount, said pilot passage and a first valve port are respectively closed by a pilot valve body and the first valve body, thereby taking a small flow rate control state. In the case that the lift amount of said second valve body goes beyond said predetermined amount, said pilot valve body is moved up by the upward movement of a valve shaft to open said pilot passage, thereby taking a large flow rate control state.