Flow Rate Control Valve Thermal Expansion Decoupling
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Solution Overview
Problem
Conventional flow rate control valves experience operational issues due to dimensional changes in the valve casing, leading to reduced sealing force and potential defective operation, especially when temperature changes occur, requiring large stepping motors and increased power consumption.
Innovation Solution
A flow rate control valve design that includes a valve guide and valve body connected via a connector, allowing axial movement within a predetermined range, with a biasing mechanism to maintain sealing force and prevent contact with the valve seat during dimensional changes, and a small lead angle for the feed screw mechanism to reduce power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the lead angle of the feed screw mechanism is increased to maintain sealing force during dimensional changes, then the sealing force is improved, but the stroke amount per step increases resulting in deterioration of flow rate control property
Solution Approach 1:
The patent introduces a dynamic decoupling mechanism where the valve guide can move independently from the valve body through a connector with predetermined movement range. This allows the valve body to maintain precise positioning for flow control while the valve guide absorbs dimensional changes from thermal expansion, resolving the contradiction between sealing reliability and control precision
Solution Approach 2:
The patent segments the valve assembly into two independent movable components: the valve body controlled by the feed screw mechanism for precise flow rate adjustment, and the valve guide that can move independently to accommodate thermal expansion. The connector with predetermined movement range couples them while allowing relative motion, enabling each component to fulfill its specific function without interfering with the other
2Reliability
If a large thrust stepping motor is used to maintain valve body seating during dimensional changes, then the sealing force is improved, but the size and cost increase
Solution Approach 1:
The patent creates a dynamic system where the valve guide moves independently to absorb dimensional changes, eliminating the need for the valve body to compensate for thermal expansion. This allows the use of a smaller stepping motor that only needs to control precise valve body positioning for flow regulation, not maintain seating against thermal variations
Solution Approach 2:
The valve guide acts as an intermediary component that absorbs thermal expansion effects, preventing these dimensional changes from being transmitted to the valve body. This mediator function allows the valve body to remain stable and properly seated without requiring excessive motor thrust
3Manufacturing precision
If the valve guide is constrained to maintain contact with the contact portion during dimensional changes, then the positioning is improved, but the sealing force is reduced due to increased distance between motor and valve seat
Solution Approach 1:
The patent implements a dynamic decoupling where the valve guide is free to move within a predetermined range relative to the valve body through the connector. This allows the valve guide to maintain contact with the contact portion for positioning stability while the valve body maintains its sealing position through independent control, resolving the contradiction between positioning precision and sealing force
Solution Approach 2:
The patent segments the positioning and sealing functions into two independent systems: the valve guide handles positioning by contacting the contact portion, while the valve body handles sealing through precise control by the stepping motor. The connector with predetermined movement range enables this functional segmentation, allowing each component to optimize its specific function without compromising the other
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 effectively maintains sealing force and prevents defective operation during dimensional changes, reduces the need for high-thrust stepping motors, and minimizes power consumption while improving flow rate control properties.
Implementation Method 1
a spring for biasing the valve body in a closing direction
Implementation Method 2
a valve guide stroke-controlled in an axial direction by the stepping motor via a feed screw mechanism
Implementation Method 3
the valve body being seated on the valve seat
Data Source
AI summary
A flow rate control valve includes: a valve casing forming a fluid passage; a valve seat provided in the fluid passage; a stepping motor; a valve guide stroke-controlled by the stepping motor via a feed screw mechanism; a valve body configured to be placed and separated on and from the valve seat; a connector connecting the valve guide and the valve body so as to allow them to move in an axial direction within a predetermined range; a valve spring biasing the valve body in a closing direction. When closing the valve body, ECU controls the motor to a closed state such that a connection between the valve guide and the valve body by the connector is released, with the valve body being seated on the valve seat, and the valve guide being situated at a non-contact position spaced away from the valve seat.