Normally-Closed Flow Rate Valve With Low-Expansion Piezo Drive
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Solution Overview
Problem
Conventional normally-closed flow rate control valves using piezoelectric elements face challenges in precisely transmitting length changes without thermal influence and adjusting pressing forces effectively, leading to potential liquid leakage or valve seat damage.
Innovation Solution
A flow rate control valve design featuring a base block with a cooling space and fin to isolate thermal influences, using a low thermal expansion support post and adjustable elastic members to ensure precise transmission of piezoelectric element changes and optimal pressing forces, while preventing diaphragm damage through surface contact with a protective plate and steel ball.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If general metal members (stainless steel) are used for the valve rod and circular cylindrical member, then the structure is simple and easy to manufacture, but thermal expansion causes imprecise transmission of the piezoelectric element's length change
Solution Approach 1:
The patent changes the material parameter (thermal expansion coefficient) of the valve rod from general metal to low thermal expansion material, enabling precise transmission of the piezoelectric element's length change by minimizing thermal expansion interference
Solution Approach 2:
The patent employs composite material structure by combining low thermal expansion material for the valve rod with general metal materials for other components, achieving both precision and manufacturability
2Reliability
If a pressing spring is used to press the diaphragm to the valve seat, then the valve can achieve closed state, but the pressing force cannot be adjusted leading to liquid leakage or valve seat damage
Solution Approach 1:
The patent transforms the static pressing spring into an adjustable elastic member system where the pressing force can be dynamically adjusted by changing the position of the adjustable member, improving both reliability and operational flexibility
Solution Approach 2:
The patent introduces an adjustable member as an intermediary between the elastic member and the diaphragm, allowing independent adjustment of the pressing force without changing the elastic member itself
3Measurement precision
If the piezoelectric element is directly connected to the diaphragm through the valve rod, then the structure is simple, but thermal expansion of the valve rod interferes with the minute length change of the piezoelectric element
Solution Approach 1:
The patent changes the thermal parameter of the transmission path by using low thermal expansion material for the valve rod, ensuring that the minute length changes of the piezoelectric element are not masked by thermal expansion of the connecting rod
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 enables precise and quick valve opening/closing operations, minimizing thermal errors and ensuring appropriate pressing forces to prevent leakage and damage, maintaining precise control of liquid flow rates.
Implementation Method 1
a piezoelectric element that expands/contracts simultaneously upon ON/OFF of voltage
Implementation Method 2
a base block with a cooling space and fin to isolate thermal influences
Implementation Method 3
using a low thermal expansion support post to ensure precise transmission of piezoelectric element changes
Implementation Method 4
adjustable elastic members to ensure precise transmission of piezoelectric element changes and optimal pressing forces
Data Source
Figure 1(a)~1(b)
Figure 2
Figure 3(a)~3(d)
AI summary
The present invention provides a normally-closed flow rate control valve capable of precisely and quickly transmitting a change in length of a piezoelectric element without thermal influence. A flow rate control valve (A) includes a base block (1) and a valve opening/closing mechanism (10). The base block (1) is provided with a valve chamber (4) in which a valve seat (3) through which a liquid raw material L flows, and a diaphragm (5) that is brought into contact with or separated from the valve seat (3) so as to close/open the valve seat (3) are installed. The valve opening/closing mechanism (10) includes a slide bearing part (20), a support post part (30), a piezoelectric actuator part (40), and a valve-actuating part (50). The slide bearing part (20) is installed on the base block 1 and is provided with a bearing (24). The support post part (30) includes a support post (31) that is inserted slidably in the bearing (24) and that moves upward and downward in a diaphragm direction. The piezoelectric actuator part (40) is equipped with a piezoelectric element (45) that presses up the support post part (30) in such a direction as to separate the support post part (30) from the diaphragm (5). The valve-operating part (50) performs opening/closing drive of the diaphragm (5) along up-and-down movement of the support post part (30). The support post (31) is made of a low thermal expansion member.