A gas-liquid dual control valve based on shape memory alloy wire driving

Abstract

The application provides a gas-liquid dual-purpose control valve driven by a shape memory alloy wire, solves the wire overload and sealing failure problems of a traditional SMA wire driven valve through double-plunger cooperative driving and elastic buffer design, a plunger one and a plunger two are coaxially sleeved in the valve body, the plunger two is driven by a pre-compressed second elastic member to realize opening and closing of a medium input valve port and limiting, the plunger one is pulled by SMA wire, and the limit displacement of the plunger one contains a redundant displacement, the first elastic member completely absorbs the remaining shrinkage of the wire, and the strain of the wire is ensured to be less than a safety threshold. Through the innovative mechanical structure design and material-mechanical cooperative optimization, the application overcomes the overload failure, sealing lag and short service life of the SMA wire driven valve, and makes a significant breakthrough in miniaturization, high reliability and long service life, and provides a new technical path for precise fluid control.

Description

Technical Field

[0001] The present invention relates to the technical field of SMA driven control valves, and in particular to a gas-liquid dual-purpose control valve driven by a shape memory alloy wire. Background Art

[0002] In the field of valve control, shape memory alloy (SMA) wire has unique superelasticity and shape memory effect. The diameter of SMA wire can be as low as 0.05-0.2mm, and the driving force per unit volume can reach 100-300MPa, far exceeding the 5-20MPa of electromagnetic actuators. The axial size of the dynamic module can be compressed to less than 5mm, which is perfectly suitable for miniaturized valve bodies. In addition, SMA drive does not require high-frequency electromagnetic fields, but only requires direct current or other drives. Its structural layout is compact and the drive is efficient and simple, giving it the advantages of miniaturization, high reliability and long life. It has been widely used in the drive control of micro valve bodies, such as lumbar support airbags or massage airbag control valves for seats. Typical SMA drive control valves in the prior art usually adopt a single plunger structure (such as Figure 1 As shown in the figure), its technical solution has the following significant defects:

[0003] 1. The problem of wire over-pull caused by hard limit: the existing valve body sets a mechanical limit structure (such as a limit boss or bayonet, etc.) at the end of the plunger to constrain the plunger displacement range. Figure 1 As shown in the figure, when the SMA wire is energized and contracts, the plunger is rigidly pulled until the sealing plug forms hard contact with the boss at the valve port. To ensure airtightness, continuous power supply is required to maintain a superelastic strain of approximately 5%-8% in the wire, far exceeding the safe operating range of SMA material (typically less than 4%). Under long-term cyclic loading, the internal dislocation density of the wire increases, leading to phase transition temperature drift and reduced actuation efficiency, significantly shortening the service life and degrading deformation performance.

[0004] 2. The contradiction between dynamic sealing and strain control: To achieve zero leakage of the medium, it is necessary to increase the contraction force of the wire material to generate a large contact pressure between the sealing plug and the valve port. This rigid sealing mechanism forces the wire material to bear a large peak stress in each movement, accelerating material fatigue failure. Existing experimental data shows that this type of valve body has a 5×10 4 After one cycle, the residual strain of the wire reaches 0.6%, and the driving displacement attenuation rate exceeds 30%.

[0005] The above technical defects lead to problems such as low reliability and short service life (usually less than 50,000 cycles) in existing SMA drive valves, which seriously restrict their application. Summary of the Invention

[0006] The present invention aims to provide a gas-liquid dual-purpose control valve driven by a shape memory alloy wire, which utilizes a double-plunger layered drive and elastic buffer mechanism. By separating the functions of plunger 2 for sealing and limiting and plunger 1 for driving the SMA wire, and coordinating the stiffness ratio of the first elastic member and the second elastic member, action decoupling and stress diversion are achieved, thereby preventing the SMA wire from being excessively stretched during the driving process and extending its service life.

[0007] To achieve the above objectives, the present invention proposes the following technical solutions:

[0008] A gas-liquid dual-purpose control valve driven by a shape memory alloy wire, comprising a valve body and a shape memory alloy wire, and also comprising a first plunger, a second plunger and an elastic component;

[0009] The valve body is provided with an axially penetrating chamber, the top of the chamber is provided with a medium input valve port, the middle is provided with a limiting boss, and the bottom is provided with a wire fixing structure;

[0010] The first plunger and the second plunger are coaxially sleeved and arranged in the chamber, and the second plunger is coaxially nested outside the first plunger to form a separable contact;

[0011] The elastic component includes a first elastic member and a second elastic member. The first elastic member is pre-compressed and arranged between the plunger 1 and the bottom of the chamber to provide an upward reset elastic force; the second elastic member is pre-compressed and arranged between the top of the plunger 2 and the top of the chamber to provide a downward driving force. The top of the plunger 2 forms a separable seal with the medium input valve port, and its axial displacement is limited by the limit displacement of the limiting boss. ;

[0012] The shape memory alloy wire is arranged in a U shape, with both ends fixed to the wire fixing structure and the middle section connected to the plunger 1. When the shape memory alloy wire contracts, it drives the plunger 1 to move axially downward to the limit displacement. satisfy ;in, The redundant displacement of the plunger 1 that can independently move downward after the plunger 2 reaches the limiting boss is provided by the deformation of the first elastic member.

[0013] As a preferred technical solution of the present invention, the redundant displacement Meet 0.1mm≤ ≤0.3mm; stiffness coefficient of the second elastic member The stiffness coefficient of the first elastic member Satisfaction: 2.0≤ ≤3.0.

[0014] As a preferred technical solution of the present invention, it also includes a valve seat, which is arranged at the upper part of the chamber and uses its bottom end as the boundary to divide the chamber into an upper valve chamber and a lower valve chamber. A positioning column is provided at the bottom of the valve seat, and an axial positioning groove is provided at the top of the positioning column. The bottom of the plunger is slidably engaged in the positioning groove, and both ends of the shape memory alloy wire pass through the valve seat and extend to the lower valve chamber and are connected to the wire fixing structure.

[0015] As a preferred technical solution of the present invention, the valve body is also provided with a medium discharge flow channel independent of the upper valve cavity, the top of the medium discharge flow channel is provided with a pressure relief port, and the end surface of the pressure relief port constitutes the limiting boss; the top of the second plunger is provided with an end plate, the lower surface of the end plate is provided with a sealing gasket that cooperates with the pressure relief port, and the upper surface of the end plate is provided with a sealing plug that cooperates with the medium input valve port.

[0016] As a preferred technical solution of the present invention, the valve seat is provided with two symmetrically distributed guide pillars, which pass through the end plate and extend to the top of the upper valve cavity. The second elastic member is sleeved on the outside of the guide pillars and clamped between the end plate and the top of the upper valve cavity.

[0017] As a preferred technical solution of the present invention, the inner wall of the medium input valve port is a tapered flow channel structure, and the sealing plug is a tapered sealing component that matches it, and the two form a line contact seal.

[0018] As a preferred technical solution of the present invention, a temperature sensor is provided in the lower valve cavity, which maintains a distance of ≤2mm from the shape memory alloy wire to monitor the working temperature of the wire in real time.

[0019] As a preferred technical solution of the present invention, the control valve can work independently as a single valve, or multiple control valves can be used in parallel combination through a manifold.

[0020] As a preferred technical solution of the present invention, the interior of the manifold is provided with three layers of horizontal flow channels arranged axially parallel and distributed sequentially from top to bottom:

[0021] The main flow channel for medium input has its inlet end connected to the medium output device, and a number of medium input branches are distributed along the axial direction on the outlet side;

[0022] The main medium output flow channel has an outlet connected to the medium chamber and a plurality of medium flow branches on the inlet side;

[0023] The main flow channel for medium discharge has several medium discharge branches on its inlet side;

[0024] All of the medium input branch ports, the medium circulation branch ports, and the medium discharge branch ports are provided on the first interface where the manifold and the valve body are connected, forming a plurality of vertically arranged first interface arrays;

[0025] The medium input valve port, the medium chamber valve port and the medium discharge port are all provided on the second interface where the valve body and the manifold are connected, forming a second interface array that matches the first interface array.

[0026] As can be seen from the above technical solutions, the technical solution of the present invention provides a gas-liquid dual-purpose control valve driven by a shape memory alloy wire, which has the following advantages compared with the prior art:

[0027] 1. Utilizing a dual-plunger layered drive and elastic buffer mechanism, the second plunger is dedicated to sealing and limiting, while the first plunger is responsible for driving the SMA wire. This, combined with the stiffness ratio of the first and second elastic members, achieves motion decoupling and stress diversion. When the second plunger, driven by the second elastic member, moves downward to the limiting boss, the first plunger can continue to move downward independently through redundant displacement. The first elastic member fully absorbs the remaining SMA wire shrinkage, ensuring wire strain is below the safety threshold of 4%, significantly extending the wire's cycle life.

[0028] 2. The tapered flow channel of the medium input valve port and the tapered sealing plug of the plunger form a linear contact seal, and the contact pressure is evenly distributed. At the same time, the radial width of the tapered gap is linearly related to the displacement, achieving precise flow control and adapting to the full medium control needs of gas and liquid.

[0029] 3. The temperature sensor in the lower valve cavity monitors the wire's operating temperature in real time to prevent overheating and phase change failure. The manifold's three-layer flow channel design enables independent layering of the media input, output, and discharge channels when multiple valves are connected in parallel, making it suitable for multi-airbag coordinated control systems.

[0030] It should be appreciated that all combinations of the foregoing concepts, as well as additional concepts described in greater detail below, to the extent such concepts are not mutually inconsistent, can be considered to be part of the inventive subject matter of this disclosure.

[0031] The foregoing and other aspects, embodiments, and features of the present invention will be more fully understood from the following description in conjunction with the accompanying drawings. Other additional aspects of the present invention, such as features and / or beneficial effects of the exemplary embodiments, will become apparent from the following description or through practice of specific embodiments according to the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The accompanying drawings are not drawn to scale. In the accompanying drawings, each identical or nearly identical component shown in various figures may be represented by the same reference numeral. For clarity, not every component is labeled in every figure. Embodiments of various aspects of the present invention will now be described by way of example with reference to the accompanying drawings, in which:

[0033] Figure 1 Schematic diagram of the plunger structure of a traditional control valve;

[0034] Figure 2 This is a front cross-sectional view of a control valve according to embodiment 1 of the present invention;

[0035] Figure 3 A side sectional view of a control valve according to embodiment 1 of the present invention;

[0036] Figure 4 Schematic diagram of the plunger structure of the control valve in closed and open states according to Example 1 of the present invention;

[0037] Figure 5 This is a front view of the control valve of Example 1 of the present invention;

[0038] Figure 6 This is a schematic structural diagram of a busbar according to Example 2 of the present invention;

[0039] Figure 7 This is a front view of a single control valve according to embodiment 2 of the present invention;

[0040] Figure 8 This is a schematic diagram of the structure of multiple control valves used in parallel according to Example 2 of the present invention;

[0041] Figure 9 Cross-sectional view of the connection structure between multiple control valves and a manifold according to embodiment 2 of the present invention.

[0042] 1: Valve body 101: Upper valve cavity 102: Lower valve cavity 103 Medium input valve port 104: Medium chamber valve port 105: Medium discharge port 2: Valve seat 201: Positioning column 202: Medium discharge flow channel 203: Guide column 204: Positioning groove 205: Pressure relief port 3: Shape memory alloy wire 4: Plunger 1 401: Fixed groove 5: Plunger 2 501: End plate 502: Sealing plug 503: Sealing gasket 6: Clamp 7: First elastic part 8: Second elastic part 9: First sealing ring 10: Second sealing ring 11: Confluence plate 1101: Medium input main flow channel 1102: Medium input branch port 1103: Medium output main flow channel 1104: Fluid outlet 1105: Medium circulation branch port 1106: Medium discharge main flow channel 1107: Medium discharge branch port. DETAILED DESCRIPTION

[0043] To further clarify the objectives, technical solutions, and advantages of the embodiments of the present invention, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only a portion of the embodiments of the present invention, not all of them. Based on the described embodiments of the present invention, all other embodiments derived by persons of ordinary skill in the art without requiring creative effort are within the scope of protection of the present invention. Unless otherwise defined, technical or scientific terms used herein shall have the ordinary meanings understood by persons of ordinary skill in the field to which the present invention pertains.

[0044] The terms "first," "second," and similar terms used in the patent specification and claims of this invention do not denote any order, quantity, or importance, but are merely used to distinguish different components. Similarly, unless the context clearly indicates otherwise, the singular forms of "a," "an," or "the" and similar terms do not denote a limitation of quantity, but rather denote the presence of at least one. Terms such as "include" or "comprising" indicate that the elements or objects preceding "include" or "comprising" encompass the features, integers, steps, operations, elements, and / or components listed after "include" or "comprising," and do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or combinations thereof. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.

[0045] Example 1

[0046] The control valve of the embodiment of the present invention includes a valve body 1, a valve seat 2, a shape memory alloy wire 3, a plunger 1 4, a plunger 2 5 and an elastic component. To ensure the sealing performance of the valve body 1 as a whole, the valve body 1 can be designed as a one-piece type with a hollow interior forming an axially through chamber; however, to facilitate the installation and maintenance of the valve body 1, the valve body 1 can also be designed as a split type. Figure 2-5As shown, the split-type valve body 1 includes an upper valve body and a lower valve body that are detachably connected. The upper valve body and the lower valve body are sealed together by a clamp 6. The interior of the upper valve body and the interior of the lower valve body are designed to be hollow structures to form an upper valve cavity 101 and a lower valve cavity 102 respectively. The upper valve cavity 101 and the lower valve cavity 102 are combined to form an axially through chamber with a certain height, which is used to provide a displacement space for axial movement of plunger 1 4 and plunger 2 5. The top of the upper valve body is provided with a medium input valve port 103 for connecting to a medium output device such as an air pump or liquid pump. Fluid media such as gas or liquid enters the control valve through this medium input valve port 103. A medium cavity valve port 104 is provided on the upper axial sidewall of the upper valve body for transferring fluid media such as gas or liquid to a cavity or container for storing media, such as a lumbar support air / liquid bag or a massage air / liquid bag. A medium discharge port 105 is provided on the lower axial sidewall of the upper valve body for discharging excess gas or liquid from the medium cavity or container to achieve pressure relief functions such as exhaust or liquid discharge. To achieve these functions, both the medium input valve port 103 and the medium cavity valve port 104 are connected to the chamber.

[0047] To ensure that the functional divisions of the chamber are clear and that the components therein do not interfere with each other, in an embodiment of the present invention, the entire chamber is divided into an upper valve chamber 101 and a lower valve chamber 102 by the valve seat 2. Specifically, the top end of the valve seat 2 abuts against the inner top end of the upper valve body, and its bottom end abuts against the stepped surface formed by the concave axial side wall inside the lower valve body, so that it is fixedly installed in the upper valve chamber 101 formed by the hollow upper valve body. The bottom end of the valve seat 2 forms a certain seal on the top end of the lower valve chamber, thereby dividing the entire chamber into a distinct upper valve chamber 101 and a lower valve chamber 102. The upper valve chamber 101 is used to accommodate fluid media such as gas or liquid, while the lower valve chamber 102 is kept sealed by a sealing device and is used to install some circuit control boards, temperature sensors and other components. The valve seat 2 of the embodiment of the present invention mainly includes a positioning column 201, a medium discharge flow channel 202 and a guide column 203. As shown in the figure, a positioning post 201 is positioned in the center of the bottom of the valve seat 2, at the junction of the upper valve cavity 101 and the lower valve cavity 102. The top of the positioning post 201 defines an upward-facing positioning groove 204 for mounting a positioning plunger 1 (4). A medium discharge channel 202 is located on one side of the valve body, independent of the upper valve cavity 201. Only the pressure relief port 205 at its top communicates with the upper valve cavity 101. The bottom opening communicates with the medium discharge port 105, used for pressure relief or discharging the medium from the medium chamber or container. Plunger 2 (5) is nested outside the positioning post 201 and movably connected to the center of the valve seat 2 with it as the central axis. To further limit and guide the axial movement of plunger 2 (5) and ensure smoother operation in conjunction with the second elastic component 8, two guide posts 203 are provided on the valve body 1, one on either side of the medium inlet valve port 103. These, in conjunction with the two second elastic members 8, provide symmetrical and balanced force on plunger 2 (5). The tops of the guide posts 203 extend to the top of the upper valve cavity 101.

[0048] like Figure 1 As shown, in the traditional single-plunger control valve, the shape memory alloy wire 3 directly drives the single plunger to complete the sealing action. In order to achieve reliable sealing of the valve port, the SMA wire needs to be continuously energized to maintain a high-strength contraction state so that it has sufficient tension to press the plug of the single plunger against the valve port, causing the wire strain to exceed its safety threshold for a long time, causing material dislocation accumulation, phase change temperature drift and a sharp drop in cycle life (usually <50,000 times). Therefore, in order to solve the above-mentioned defects, the present invention innovatively adopts a dual-plunger collaborative drive structure, combining the mechanical collaboration of two groups of elastic components to achieve action decoupling and stress diversion. Specifically, the traditional single plunger is functionally separated by a dual-plunger design. For example, the plunger 2 5 in the embodiment of the present invention is responsible for sealing and limiting. It is pushed downward quickly by the pre-compressed second elastic member 8 to open the medium input valve port 103 and block the pressure relief port 205 of the medium discharge channel 202, and its maximum axial downward displacement is The plunger 4 is directly driven by the SMA wire, which can move downward along the axis to the limit displacement , through the non-fixed connection contact with the plunger 2 5, after losing the constraint imposed by the plunger 2 5, the plunger 1 4 still has redundant displacement that can move downward independently , the redundant displacement is provided by the deformation of the first elastic member acting thereon and satisfies , 0.1mm≤ ≤0.3mm.

[0049] The specific implementation of the double plunger and the elastic component is that the double plunger includes a plunger 4 and a plunger 5, and the elastic component includes a rigidity coefficient of The first elastic member 7 and the two rigidity coefficients are The second elastic member 8, 2.0≤ ≤3.0, to ensure that the plunger 2 takes priority. Figure 3-4 As shown, preferably, the first elastic member 7 and the second elastic member 8 of the embodiment of the present invention are both springs, and the rigidity coefficients are The first spring and stiffness coefficient are In order to make the valve body 1 compact and make full use of the limited space of the chamber, the positioning column 201, the plunger 1 4 and the plunger 2 5 are connected by a coaxial sleeve structure from the inside to the outside. Therefore, the positioning column 201, the plunger 1 4 and the plunger 2 5 of the embodiment of the present invention are all designed to be cylindrical. Figure 2-3As shown, plunger 2 (5) has a downwardly opening internal cavity, allowing it to coaxially and flexibly fit over the exterior of plunger 1 (4) and positioning post (201). Plunger 1 (4) is located in the space above the internal cavity of plunger 2 (5), with the two forming a detachable contact via contacting end surfaces (the top surface of the internal cavity of plunger 2 (5) and the top surface of plunger 1 (4), without a rigid connection. Positioning post (201) is located in the lower space of plunger 2 (5), and the bottom of plunger 1 (4) flexibly engages in positioning groove (204). To accommodate the cylindrical structure of plunger 1 (4), positioning groove (204) is designed as a circular groove. To increase the stability of plunger 1 (4) during axial movement, the outer diameter of the bottom of plunger 1 (4) matches the inner diameter of positioning groove (204). Positioning groove (204) provides a guiding and limiting effect, ensuring smoother movement of plunger 1 (4). The bottom end of plunger 1 (4) defines an axially recessed fixing groove (401). The top end of the first elastic member (7) is connected to the fixing groove (401), and its bottom end is connected to the end wall of the positioning groove (204). This serves to cushion the tension when plunger 1 (4) is forced downward, while also providing redundant displacement for plunger 1 (4) to move downward independently, preventing it from being subjected to rigid tension like a conventional plunger and excessive contraction and tension of the shape memory alloy wire (3). Furthermore, when the tension is released, plunger 1 (4) is pushed upward to reset itself. The top end of plunger 2 (5) is provided with an end plate (501). The top surface of end plate (501) is provided with a sealing plug (502) that mates with the medium inlet valve port (103). The sealing plug (502) tightly seals the medium inlet valve port (103). Two second elastic members (8) are disposed between the top end of the end plate (501) and the top end of the upper valve chamber (101) and are in a pre-compressed state. The second elastic members (8) drive plunger 2 (5) to move axially downward under the guidance of the guide post (203), opening the medium inlet valve port (103). Furthermore, the two guide posts 203 extend through the end plate 501 to the top of the upper valve chamber 101, and the second elastic member 8 is sleeved on the outside of the guide posts 203 between the end plate 501 and the top of the upper valve chamber 101. The first end of the second elastic member 8 is connected to the end plate 501, and the second end is connected to the top of the upper valve chamber 101. To further enhance the sealing of the valve body 1 as a whole and the sealing between the upper and lower valve bodies, a first sealing ring 9 is provided between the connecting side wall of the upper and lower valve bodies and the valve seat 1, and a second sealing ring 10 is provided between the second plunger 5 and the valve body 1.

[0050] In the aforementioned dual-plunger design, the shape memory alloy wire 3 forms a direct driving relationship only with plunger 1 4. There are various connection methods between the two, as well as various heating methods for the shape memory alloy wire 3, which can be selected based on the specific connection method between the shape memory alloy wire 3 and plunger 1 4. For example, a single wire can be used to pull plunger 1 4 directly. One end of the wire is fixedly connected to plunger 1 4, while the other end extends through the positioning column 201 to the bottom end of the lower valve chamber 102 and is fixed to the wire fixing structure, forming a single-sided linear pulling drive path. This connection method allows for indirect heating of the SMA wire, such as by filling the lower valve chamber 102 with a heat-conducting medium to heat the wire. However, this pulling drive method is a single-point fixing method. Single-point fixing of the wire leads to local strain gradients greater than 15%, which can easily cause cracks at the anchor end. Relying on heat conduction to achieve phase change contraction of the wire can also easily lead to a large deviation between the actual wire temperature and the set temperature, resulting in poor phase change stability. Therefore, the embodiment of the present invention adopts a U-shaped connection traction method with better pulling drive effect, as well as an electric heating method. Specifically, a circuit control board is provided at the bottom of the lower valve chamber, on which a wire fixing structure such as a positive and negative electrode holder is provided for connecting and fixing the two ends of the wire. An inverted U-shaped hook groove is provided on the plunger 4, and the SMA wire is pre-formed into an inverted U-shaped structure (so the effective length of the wire is the total expanded length of the bilateral path). The two ends of the wire extend from the two sides of the plunger 4 through the positioning column 201 to the lower valve chamber 102 and are respectively fixedly connected to the positive and negative electrode holders. The middle U-shaped overhanging section of the wire is embedded in the hook groove on the plunger 4, forming a bilateral linear pulling drive path and a current loop directly connected to the control circuit through the electrode holder. When power is applied, current flows through the entire length of the U-shaped wire, achieving Joule effect self-heating, thereby causing the wire to contract and pull the plunger 4. This connection method disperses stress through geometric optimization, extends the service life of the wire, eliminates thermal conduction hysteresis, and achieves millisecond-level dynamic response. In addition, the partition design structure of the upper valve chamber 101 and the lower valve chamber 102 prevents the medium fluid in the upper valve chamber 101 from entering the lower valve chamber 102, thereby not affecting the electronic components in the lower valve chamber, making wire control more precise.

[0051] To improve drive reliability and extend wire life, a real-time temperature monitoring module, such as a temperature sensor or other temperature measurement component, is integrated within lower valve chamber 102 to measure the ambient temperature near the wire. To accurately measure the wire temperature, the temperature sensor maintains a distance of ≤2 mm from the shape memory alloy wire. Furthermore, the temperature sensor is preferably integrated into the circuit control board.

[0052] During the opening and closing process of a conventional planar sealing valve, the flow rate may not change linearly. This is because when the plunger moves slightly, the flow channel suddenly opens, and the flow rate may increase dramatically. During this process, the cross-sectional area of ​​the valve port changes nonlinearly with the plunger displacement, making it difficult for the contraction of the SMA wire to form a linear relationship with the medium flow rate. Therefore, to avoid the problem of sudden increase in flow rate caused by the sudden opening of the flow channel, the embodiment of the present invention processes the inner wall of the medium input valve port into a tapered flow channel with a fixed taper angle, and designs the sealing plug 502 into a conical columnar structure that closely matches the tapered flow channel. When the two cooperate, an annular linear contact seal is formed, which not only ensures sealing reliability but also avoids stress concentration caused by planar contact. At the same time, when the SMA wire contracts and indirectly causes the plunger 2 5 to move downward, a uniform annular gap is formed between the conical columnar sealing plug 502 and the medium input valve port. The radial width of the gap is proportional to the displacement of the plunger 2, so that the cross-sectional area of ​​the flow channel increases linearly with the displacement, thereby achieving precise linear control of the wire contraction and flow rate. Through the collaborative design of elastic drive of the tapered flow channel and the tapered sealing plug, the present invention converts the nanoscale deformation of the SMA wire into a macroscopic linear flow output of the medium, providing a new technical path for precision fluid control systems.

[0053] In order to realize the sealing and limiting function of plunger 2 5, the upper limit position of plunger 2 5 is limited by the end face of the medium input valve port 103. At this time, the sealing plug 502 at the top of plunger 2 5 is tightly sealed in the medium input valve port 103, limiting the upward movement of plunger 2 5; the lower limit position of plunger 2 5 is determined by the limiting protrusion provided in the upper valve cavity 101. The limiting protrusion can be provided on the axial side wall of the upper valve cavity 101 or on the valve seat 1, and both are located below the end plate 501. When the end plate 501 moves downward with plunger 2 5, it will be blocked by the limiting protrusion, thereby limiting the further downward movement of plunger 2 5. In order to make the internal structure layout of the valve body 1 compact and the functions highly integrated, the present invention uses the end face of the pressure relief port 205 at the upper end of the medium discharge flow channel 202 as the limiting surface of the limiting protrusion, integrating the medium discharge flow channel 202 and the limiting protrusion into one. Specifically, when plunger 2 (5) moves downward until it contacts the end surface of end plate 501 where pressure relief port 205 is located, a hard limit is placed on the downward displacement of plunger 2 (5). Simultaneously, the lower surface of end plate 501 seals medium discharge channel 202, effectively shutting off medium discharge. This functional coupling of mechanical limit and channel sealing is achieved. To achieve a tight seal against pressure relief port 205 in medium discharge channel 202, a sealing gasket 503 is provided on the lower surface of end plate 501, which mates with pressure relief port 205.

[0054] This embodiment of the present invention innovatively integrates the pressure relief port 205 at the upper end of the medium discharge flow channel 202 with the position limiting surface. This structural reuse optimizes space and improves performance, resolving the drawbacks of traditional plunger-type control valves, where the position limiting function typically relies on independent position limiting bumps, resulting in a loose valve body structure and redundant flow channel layout. By deeply integrating the position limiting function into the medium discharge flow channel structure, the physical limitations of traditional valve body spatial layout are overcome while ensuring precise displacement control.

[0055] The operating principle of Example 1 of the present invention is as follows, taking gas as an example, including the following states:

[0056] Initial state when not in use: External equipment is connected, medium input valve port 103 is connected to the air pump, and medium chamber valve port 104 is connected to an airbag (such as a massage airbag or lumbar support airbag). The SMA wire is not powered and is at its original length. No tension is applied to plunger 1 4, and valve body 1 is closed. Plunger 2 5 is pushed against medium input valve port 103 by the upward force of plunger 1 4, and is sealed by sealing plug 502. Second elastic member 8 is pre-compressed. First elastic member 7 applies an upward pre-compressive force to plunger 1 4, enabling plunger 1 4 to overcome the pre-compressive force of second elastic member 8 and push plunger 2 5 against medium input valve port 103.

[0057] During inflation: the SMA wire contracts when energized and heated, overcoming the resistance of the first elastic member 7 to pull the plunger 1 4 downward, thereby canceling part of the driving force of the plunger 2 5 and making room for the downward movement of the plunger 2 5; the plunger 2 5 is pushed downward by the elastic force of the second elastic member 8, and the sealing plug 502 at its top gradually separates from the medium input valve port 103, and the gas enters the upper valve cavity 101, and then enters the airbag through the medium cavity valve port 104. The downward displacement of the plunger 2 5 is limited by the end face of the pressure relief port 205. When the end plate 501 presses against the pressure relief port 205, the plunger 2 5 is forced to stop moving downward and the medium discharge flow channel 202 is also closed, and it is in a fully inflated state. At this time, the plunger 2 5 reaches its limit displacement. But the plunger 4 is different. At this time, after it is freed from the constraint of the plunger 5, it can still be pulled by the wire contraction to overcome the resistance of the first elastic member 7 and move down a certain displacement independently, that is, the redundant displacement of the anti-over-pull design of the present invention , The deformation of the first elastic member 7 provides the residual shrinkage of the shape memory alloy wire 3. Complete absorption, therefore, the plunger 4 can move to the limit displacement , 0.1mm≤ ≤0.3mm. Therefore, when inflating, the gas flow path is: medium input valve port 103 → upper valve cavity 101 → medium chamber valve port 104 → airbag.

[0058] During deflation, the SMA wire loses power, cools, and returns to its original length. Plunger 1 (4) is pushed upward to its original position by the restoring force of first elastic member 7, completing its reset. Plunger 2 (5) is then pushed upward by plunger 1 (4), disengaging end plate 501 from pressure relief port 205 of medium discharge channel 202 until its upper end surface presses against medium inlet valve port 103, sealing it. The second elastic member 8 is compressed back to its original position. At this point, the gas flow path is: medium chamber valve port 104 → upper valve chamber 101 → medium discharge channel 202 → medium discharge port 105.

[0059] for The calculation method can be derived from the forces and displacements of the SMA wire, plunger 1 4, plunger 2 5 and the elastic component:

[0060] Analysis of the initial state of the system:

[0061] 1. The SMA wire is at its original length and no tension is applied;

[0062] 2. Second elastic member 8 (rigidity coefficient ) is pre-compressed, the compression amount is , push plunger 25 downwards, ;

[0063] 3. First elastic member 7 (rigidity coefficient ) by its initial compression Provide upward momentum , ;

[0064] Therefore, when the second plunger is stationary, the force of the first elastic member 7 needs to balance the pre-compression force of the second elastic member 8, and the two are equal, resulting in:

[0065] （1）

[0066] Work process analysis:

[0067] After power is applied, the SMA wire generates tension (In the embodiment of the present invention, it is the vector sum of the pulling forces on both sides of the U-shaped path), driving the plunger 1 4 to move downward, causing the plunger 2 5 to move downward synchronously, including two stages;

[0068] Stage 1: Plunger 25 moves down (0→ ), dominated by the second elastic member 8, the compression amount of the second elastic member 8 is reduced to , providing downward force ; Plunger 14 moves down synchronously to make way for displacement , so that the compression amount of the first elastic member 7 increases to ;

[0069] Stage 2: Plunger 1 (4) is not constrained by plunger 2 (5) and can move downward independently under the pull of the wire. ( → ), the compression amount of the first elastic member 7 increases to , the upward thrust provided is .

[0070] Tensile force generated by SMA wire The combined force of the entire system needs to be balanced, so:

[0071] (2)

[0072] Substituting formula (1) into formula (2), we can obtain

[0073] (3)

[0074] The derivation process of the above model is carried out under ideal conditions, including the following: ignoring coefficient friction dissipation; ignoring the elastic deformation of seals (such as sealing plugs and gaskets); assuming uniformity of the temperature field; ignoring the influence of the plunger's own weight. For the last factor, because in the design of micro valve bodies, the plunger is usually made of lightweight materials (such as aluminum alloys, titanium alloys or composite materials), its mass is extremely small, combined with the following factors, the influence of the plunger's weight on the mechanical balance can be ignored. SMA wire has a high driving force. The driving force per unit volume of SMA wire is as high as 100-300MPa, which far exceeds the order of magnitude of the plunger's gravity. For example, if the mass of the plunger is 1g, the gravity is m*g=0.001kg*9.8m / s2≈0.01N, and the wire driving force is usually ≥1N, gravity accounts for less than 1%. Therefore, the contribution of gravity to the initial balance can be ignored. The simplified model of the embodiment of the present invention achieves accurate prediction of redundant displacement by reasonably ignoring minor interference factors while retaining the core mechanical elements, providing a reliable theoretical framework for structural parameter optimization. In addition, according to the working principle of the embodiment of the present invention, in order for the control valve to work properly, the total driving force provided by the shape memory alloy wire is satisfy: .

[0075] Despite the above redundant displacement The theoretical model is based on idealized assumptions, but its core value lies in revealing the elastic stiffness coefficient ratio ( ) and redundant displacement A linear mapping relationship. Those skilled in the art should understand that interference factors such as friction coefficient, elastic deformation of seals and assembly tolerances in actual working conditions will introduce high-order correction terms, such as friction correction terms, seal stiffness correction terms, etc. However, the essence of these corrections is the superposition operation or iterative optimization based on the basic model of the present invention, which belongs to the category of conventional mechanical analysis. The actual model containing interference factors can be established through finite element simulation or experimental calibration, and this process does not involve creative labor. Therefore, the scope of the claims of the present invention covers all deformation implementation methods based on the model.

[0076] In the description of Example 1 above, the solution to the problem of wire over-tension / overload by the dual-plunger coordinated drive and elastic buffer mechanism has been revealed from the structural principle level. In order to further quantitatively verify the effectiveness of this design in wire strain control, a numerical analysis is now carried out in combination with typical working condition parameters. Based on the size of a general control valve, the length of the shape memory alloy wire 3 used is taken as 60mm (the total unfolded length of the U-shaped wire, and the length of one side of the wire is 30mm). The stroke of the plunger 2 to fully open / close the medium input valve port is used as the limit. Different medium fluids have certain requirements for flow accuracy. The gas-liquid dual-purpose control valve of the embodiment of the present invention is also the same. In order to adapt to the sealing requirements of different medium fluids, generally Meet 0.55mm≤ ≤1.0mm; assuming that the total driving force provided by the wire is 20N (the vector sum of the tension on both sides of the U-shaped wire, and 10N on one side), the safe strain threshold of the SMA wire is 4%, that is, as long as the strain of the SMA wire does not exceed 4% of the original length, it is within the safe range and has not reached the over-tension state. The above formula is used to verify the anti-over-tension effect of the wire. The specific results are shown in Table 1 below:

[0077] Table 1

[0078]

[0079] Table 1 lists the wire strain calculation results under three sets of core parameter combinations. ) and the ultimate displacement of the plunger 2 5, verifying the redundant displacement The shunt buffering effect on the wire strain is achieved by redundant displacement during the SMA wire driving process. The stiffness ratio of the elastic component is optimized to strictly control the wire strain within the safety threshold (<4%). Within the range of values ​​(0.1-0.3mm), even if the limit displacement of the plunger 25 reaches 1.0 (corresponding to the maximum flow demand condition), the strain of the SMA wire is always strictly controlled below 3.67%, which is lower than the safety threshold of 4%. This fully proves that: through The redundant displacement design and the coordinated optimization of the stiffness ratio of the two sets of elastic parts successfully limit the working strain of the wire material to the safe service range of the material, fundamentally overcoming the overload failure defect of the traditional single plunger control valve. In particular, even if Even when the strain reaches the upper limit of 0.3mm, it is still within the safety threshold, indicating that this design not only ensures basic safety, but also leaves sufficient safety margin to cope with extreme working conditions, demonstrating its outstanding engineering robustness. ) increases from 2.0 to 3.0, the limit displacement of the plunger 5 increases from 0.55mm to 1.0mm, and The decrease from 0.3mm to 0.1mm indicates that by adjusting the stiffness ratio, the displacement contributions of plunger 1 4 and plunger 2 5 can be flexibly distributed, giving priority to ensuring that plunger 2 5 completes the sealing action, while plunger 1 4 is responsible for absorbing the remaining strain. The larger the , the higher the total shrinkage of the wire, but the strain is still controlled within a safe range through the coordinated design of the stiffness ratio of the elastic parts.

[0080] In the technical solution of this embodiment, the parameters listed in Table 1, such as the wire length, the limit displacement of plunger 2 5, and the safety strain threshold, are only preferred implementations of the embodiment of the present invention. Their specific numerical ranges are guiding quantitative boundaries based on the engineering practice of typical micro-control valves. It should be emphasized that the core innovation of the present invention lies in the mechanical architecture design of dual-plunger cooperative drive and elastic buffering, and the resulting technical concept of coordinated optimization of redundant displacement and stiffness ratio. For parameter deviations caused by fluid medium characteristics (such as the viscosity difference between gas and liquid), control accuracy requirements, or miniaturization adjustment in actual applications, as long as they are still based on the core design principles of functional decoupling of plunger 1 4 and plunger 2 5 and redundant displacement absorbing the residual shrinkage of the wire, they should be regarded as equivalent replacements or conventional adjustments to the technical solution of this patent.

[0081] Example 2

[0082] The main difference between Example 2 and Example 1 is that Example 1 is a single valve control scenario, while Example 2 is a combination of multiple control valves in parallel. The specific implementation is as follows:

[0083] like Figure 6-9 As shown, when multiple valve bodies are used in parallel, a manifold 11 needs to be added to connect them in parallel, such as Figure 6As shown, the manifold 11 is internally provided with three layers of horizontal flow channels arranged axially parallel to each other. The upper layer is the main medium input flow channel 1101, whose inlet is connected to a medium output device (such as an air pump or liquid pump). Several medium input branches 1102 are axially distributed on the outlet side. The middle layer is the main medium output flow channel 1103, whose outlet side is provided with multiple fluid outlets 1104 for connecting to medium cavities (such as the air inlet pipe of an airbag or the liquid inlet pipe of a liquid sac), and whose inlet side is provided with several medium circulation branches 1105. The lower layer is the main medium discharge flow channel 1106, whose inlet side is provided with several medium discharge branches 1107. The medium input branches 1102, the medium circulation branches 1105, and the medium discharge branches 1107 are all provided on the first interface connecting the manifold 11 and the valve body 1, forming multiple groups of vertically arranged first interface arrays.

[0084] The relative positions of the medium input valve port 103 and the medium chamber valve port 104 in Example 1 are changed, and the two, along with the medium discharge port 105, are centrally located on the second interface connecting the valve body 1 and the manifold 11. The medium input valve port 103, the medium chamber valve port 104, and the medium discharge port 105 form a second interface array on the second interface of the valve body 1 that matches the first interface array. The medium input valve port originally located at the top can be connected to the second interface via a curved flow channel, thereby achieving a centralized opening arrangement of the valve body 1.

[0085] While the present invention has been disclosed above with reference to preferred embodiments, this is not intended to limit the present invention. Persons skilled in the art will readily appreciate that various modifications and variations can be made without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the claims.

Claims

1. A gas-liquid dual-purpose control valve driven by a shape memory alloy wire, comprising a valve body (1) and a shape memory alloy wire (3), characterized in that: Also includes plunger one (4), plunger two (5) and an elastic component; The valve body (1) is provided with an axially penetrating chamber inside, the top of the chamber is provided with a medium input valve port (103), the middle is provided with a limiting boss, and the bottom is provided with a wire fixing structure; The plunger 1 (4) and the plunger 2 (5) are coaxially sleeved and arranged in the chamber, and the plunger 2 (5) is coaxially nested outside the plunger 1 (4) to form a separable contact; The elastic component includes a first elastic member (7) and a second elastic member (8). The first elastic member (7) is pre-compressed and arranged between the plunger 1 (4) and the bottom of the chamber to provide an upward return elastic force; the second elastic member (8) is pre-compressed and arranged between the top of the plunger 2 (5) and the top of the chamber to provide a downward driving force. The top of the plunger 2 (5) forms a separable seal with the medium input valve port (103), and its axial displacement is limited by the limit displacement of the limiting boss. ; The shape memory alloy wire (3) is arranged in a U shape, with both ends fixed to the wire fixing structure and the middle section connected to the plunger 1 (4). When the shape memory alloy wire (3) contracts, it drives the plunger 1 (4) to move axially downward to the limit displacement. satisfy ;in, The redundant displacement of the plunger 1 (4) that can be independently moved downward after the plunger 2 (5) reaches the limiting boss is provided by the deformation of the first elastic member (7); The redundant displacement Meet 0.1mm≤ ≤0.3mm; stiffness coefficient of the second elastic member (8) The stiffness coefficient of the first elastic member (7) Satisfaction: 2.0≤ ≤3.0; It also includes a valve seat (2), the valve seat (2) being arranged at the upper part of the chamber and dividing the chamber into an upper valve chamber (101) and a lower valve chamber (102) with its bottom end as the boundary; The valve body (1) is further provided with a medium discharge flow channel (202) independent of the upper valve cavity (101), and a pressure relief port (205) is provided at the top of the medium discharge flow channel (202), and the end surface of the pressure relief port (205) constitutes the limiting boss; an end plate (501) is provided at the top of the plunger 2 (5), and a sealing gasket (503) cooperating with the pressure relief port (205) is provided on the lower surface of the end plate (501), and a sealing plug (502) cooperating with the medium input valve port (103) is provided on the upper surface of the end plate (501).

2. The gas-liquid dual-purpose control valve driven by shape memory alloy wire according to claim 1, characterized in that: A positioning column (201) is provided at the bottom of the valve seat (2), and an axial positioning groove (204) is provided at the top of the positioning column (201). The bottom of the plunger (4) is slidably embedded in the positioning groove (204). Both ends of the shape memory alloy wire (3) pass through the valve seat (2) and extend to the lower valve cavity (102) to be connected to the wire fixing structure.

3. The gas-liquid dual-purpose control valve driven by shape memory alloy wire according to claim 1, characterized in that: The valve seat (2) is provided with two symmetrically distributed guide pillars (203), the guide pillars (203) passing through the end plate (501) and extending to the top of the upper valve cavity (101), and the second elastic member (8) is sleeved on the outside of the guide pillars (203) and clamped between the end plate (501) and the top of the upper valve cavity (101).

4. The gas-liquid dual-purpose control valve driven by shape memory alloy wire according to claim 1, characterized in that: The inner wall of the medium input valve port (103) is a tapered flow channel structure, and the sealing plug (502) is a tapered sealing component that matches it, and the two form a line contact seal.

5. The gas-liquid dual-purpose control valve driven by shape memory alloy wire according to claim 1, characterized in that: A temperature sensor is provided in the lower valve cavity (102), which maintains a spacing of ≤2 mm from the shape memory alloy wire (3) to monitor the working temperature of the wire in real time.

6. The gas-liquid dual-purpose control valve driven by a shape memory alloy wire according to any one of claims 1 to 5, characterized in that: The control valve can work independently as a single valve, or a plurality of control valves can be used in parallel combination through a manifold (11).

7. The gas-liquid dual-purpose control valve driven by shape memory alloy wire according to claim 6, characterized in that: The manifold (11) is provided with three layers of horizontal flow channels arranged in axial parallel and distributed sequentially from top to bottom: A medium input main flow channel (1101), the inlet end of which is connected to the medium output device, and the outlet side of which has a plurality of medium input branches (1102) distributed along the axial direction; A medium output main flow channel (1103), the outlet side of which is connected to the medium chamber, and the inlet side is provided with a plurality of medium flow branches (1105); A main medium discharge flow channel (1106) is provided with a plurality of medium discharge branches (1107) on its inlet side; All of the medium input branch ports (1102), the medium circulation branch ports (1105), and the medium discharge branch ports (1107) are provided on a first docking surface where the manifold (11) is connected to the valve body (1), forming a plurality of vertically arranged first interface arrays; The medium input valve port (103), the medium chamber valve port (103) and the medium discharge port (105) are all provided on a second docking surface where the valve body (1) is connected to the manifold (11), forming a second interface array that matches the first interface array.

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