Fluid one-way control unit and application thereof

Abstract

The invention discloses a fluid one-way control unit which comprises an asymmetric deformable porous membrane and self-adaptive functional liquid, the self-adaptive functional liquid at least partially infiltrates the asymmetric deformable porous membrane, and the self-adaptive functional liquid and the asymmetric deformable porous membrane are matched to form a fluid control channel; wherein the asymmetric deformable porous membrane is formed by compounding a rigid porous layer and an elastic porous layer and correspondingly forms a rigid part and an elastic part, and the threshold pressure intensity of the fluid passing through the control channel from the rigid part is different from the threshold pressure intensity of the fluid passing through the control channel from the elastic part, so that the membrane passing direction of the fluid can be controlled. The invention further discloses application of the fluid one-way control unit in a differential fluid control system. The fluid one-way control unit forms a plurality of control areas in different folding states through folding operation so as to achieve the system with different fluid flow output. The invention has the principle characteristics of flexibility, multiple functions and miniaturization, and the fluid flow is logically controlled so as to meet various practical applications.

Description

Technical Field

[0001] The invention belongs to the technical and application field of fluid flow control, and in particular relates to the design and use of a fluid one-way control unit. Background Art

[0002] With the development of comprehensive science and technology, the fluid flow control process has played an important role in frontier fields such as air supply of fuel cells, flow control of medical ventilators, sequential drive of soft robots, pneumatic clamps of progressive chemical instruments, and ink dispensers for 3D printing. At present, there are two most commonly used action mechanisms for fluid flow control, namely mechanical control fluid mechanisms with moving structures and fluid mechanisms based on jet interactions. The mechanical parts of mechanical control fluid mechanisms are generally stable, reliable, and durable, but they have disadvantages such as large size, high noise, single function, and complex design and manufacturing; while the fluid in the fluid mechanism based on jet interaction does not have a moving structure, but requires continuous flow consumption during use. Therefore, it is necessary to develop new fluid flow control systems to meet the needs of technological manufacturing development. Summary of the invention

[0003] The present invention aims at the deficiencies in the prior art and provides a fluid one-way control unit system.

[0004] In order to achieve the above purpose, the technical solution of the present invention is:

[0005] A fluid unidirectional control unit comprises an asymmetric deformable porous membrane and an adaptive functional liquid, wherein the adaptive functional liquid at least partially infiltrates the asymmetric deformable porous membrane and the two cooperate to form a fluid control transport channel; wherein the asymmetric deformable porous membrane is composed of a rigid porous layer and an elastic porous layer and respectively constitutes a rigid part and an elastic part, and the threshold pressure of the control fluid when passing through the rigid part is different from the threshold pressure of the control fluid when passing through the elastic part, so as to realize differentiated fluid control, that is, directional control of the fluid passing through the membrane.

[0006] The microporous structure of the asymmetric deformable porous membrane injected with adaptive functional liquid can realize the controlled flow of fluid by manipulating the threshold pressure. The threshold pressure is related to the surface chemical properties, pore geometry and interfacial tension. Asymmetric deformable porous membranes with different mechanical properties and surface chemical properties can realize different forms of fluid control transport behavior. For example, if the fluid is controlled to move in one direction (defined as the pressure threshold P required for the fluid to pass through the rigid part), the threshold pressure can be controlled by the pressure threshold P. R , a pressure threshold P is required to pass from the elastic part E ). Since the asymmetric deformable porous membrane will deform when passing through the elastic part, affecting the thickness and pore size, when the pressure threshold P E >P R, if P is applied to the fluid one-way control liquid gating unit R <P Apply <P E With constant pressure, the fluid will flow through the rigid part but not the elastic part, thus achieving one-way fluid control.

[0007] The fluid includes but is not limited to gaseous fluid and liquid fluid.

[0008] Optionally, the difference in elastic modulus between the rigid porous layer and the elastic porous layer is 9 to 13 times.

[0009] Optionally, the pore size distribution of the rigid porous layer is between 0 and 5 μm, and the pore size distribution of the elastic porous layer is between 0 and 3 μm.

[0010] Optionally, the thickness ratio of the elastic porous layer to the rigid porous layer is 1:5 to 5:2.

[0011] Optionally, the mass ratio of the elastic porous layer PVDF to PAN is 4:1 to 6:4, and when the blending ratio is 6:4, it has an optimal fiber-based structure and a maximum threshold pressure difference with the rigid porous layer.

[0012] Optionally, the rigid porous layer is a polyvinylidene fluoride layer, and the elastic porous layer is a polyvinylidene fluoride / polyacrylonitrile layer; the polyvinylidene fluoride layer and the polyvinylidene fluoride / polyacrylonitrile layer are respectively formed by electrospinning processes, and the polyvinylidene fluoride / polyacrylonitrile layer is directly spun on the polyvinylidene fluoride layer.

[0013] Different electrospinning parameters will affect the micromorphology of the porous membrane and cause changes in the threshold pressure difference. The threshold pressure difference on both sides of the asymmetric deformable porous membrane can still be achieved by changing the solution ratio, stirring time, injection speed, receiving speed, translation speed, translation distance, needle model, voltage, ambient temperature and humidity, electrospinning time, etc. within a certain range.

[0014] Optionally, the contact angle of the adaptive functional gating liquid on the rigid porous layer and the elastic porous layer is less than 60°.

[0015] The adaptive functional liquid must strongly wet the asymmetric deformable porous membrane to ensure thermodynamic stability and not dissolve or chemically react with the transport fluid. Taking air as an example, the adaptive functional liquid can be liquid paraffin, silicone oil, or other K series lubricants such as Krytox 103.

[0016] Based on the above-mentioned fluid unidirectional control unit design principles, a differentiated fluid control system can be constructed, including an input channel, a differentiated control unit and multiple output channels; the differentiated control unit is formed by the above-mentioned fluid unidirectional control unit through a folding operation to form multiple gating areas in different folding states, and the multiple gating areas in different folding states have different fluid transmembrane threshold pressures; the differentiated control unit is arranged between the input channel and the output channel, and the control area and the output channel correspond one-to-one to achieve differentiated output of different output channels.

[0017] Optionally, the folding operation includes cutting the asymmetric deformable porous membrane and then performing differential folding on different regions, and the folded states include single-layer, double-layer and multi-layer formed by no folding, half folding and multiple folding.

[0018] The fluid one-way control unit can be designed for use in gas drives.

[0019] A pneumatic mechanical device comprises the above-mentioned differentiated fluid control system and a plurality of action units, wherein the plurality of output channels act on the plurality of action units one by one, and the differentiated actions of the plurality of action units are controlled by controlling the fluid input pressure of the input channel. The beneficial effects of the present invention are:

[0020] 1) Fluid unidirectional control unit, through the synergistic effect of asymmetric deformable porous membrane and functional liquid injection, different threshold pressures are applied in different membrane directions, which can realize the control of unidirectional fluid flow. It has the principle characteristics of flexibility, multi-function and miniaturization, and can logically manipulate gas flow to meet various practical applications, overcoming the shortcomings of existing mechanisms for controlling fluid movement.

[0021] 2) A differentiated fluid control system based on a fluid unidirectional control unit can construct folding states with different pressure thresholds through differentiated folding operations to achieve different gating areas. A variety of logical relationships between output signals and input signals can be designed. Various flow patterns can be programmed by setting multi-valued logic gates to achieve differentiated outputs. When applied to gas drives, it can realize the control of differentiated actions of different action units. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 The preparation process and principle diagram of the fluid one-way control unit of Example 1;

[0023] Figure 2 (a) is the compressive stress-strain curve of the rigid polyvinylidene fluoride (PVDF) layer and the elastic polyvinylidene fluoride / polyacrylonitrile (PVDF / PAN) layer of Example 1, and (b) the deformation before and after compression;

[0024] Figure 3(a) is the thickness ratio T between the elastic polyvinylidene fluoride / polyacrylonitrile (PVDF / PAN) layer and the rigid polyvinylidene fluoride (PVDF) layer in Example 1 E / T R With P E / P R (b) The blending ratio of PVDF and PAN in the elastic polyvinylidene fluoride / polyacrylonitrile (PVDF / PAN) layer E , P R The relationship between the pressure difference ΔP on both sides;

[0025] Figure 4 The figure is a schematic diagram of the fluid unidirectional control unit of Example 2 forming an OR and AND logic gate, in which the dark surface is a rigid part and the light surface is an elastic part;

[0026] Figure 5 This is a schematic diagram of a multi-valued logic gate formed by a fluid unidirectional control unit of Example 3, in which the dark surface is a rigid part and the light surface is an elastic part;

[0027] Figure 6 This is a schematic diagram showing a comparison of the ventilation transmembrane threshold pressures of the fluid unidirectional control unit in different folding modes of Example 3, in which the dark surface is the rigid part and the light surface is the elastic part;

[0028] Figure 7 It is a structural schematic diagram of a differentiated fluid control system of Example 3;

[0029] Figure 8 is a schematic structural diagram of a pneumatic mechanical device of Example 4;

[0030] Fig. 9 Schematic diagram of different action states of the pneumatic mechanical device of Example 4. DETAILED DESCRIPTION

[0031] The present invention is further explained below in conjunction with the accompanying drawings and specific embodiments. The various drawings of the present invention are only for illustration to make it easier to understand the present invention, and the specific proportions can be adjusted according to design requirements. The upper and lower relationships of the relative elements and the definitions of the front / back in the figures described in the text should be understood by those skilled in the art to refer to the relative positions of the components, so they can all be flipped to present the same components, which should all fall within the scope disclosed in this specification.

[0032] The fluid in the embodiments is airflow. It can be understood that other fluids can also achieve the same technical effect.

[0033] Example 1

[0034] A fluid unidirectional control unit, composed of an asymmetric deformable porous membrane and an adaptive functional liquid. Figure 1 The asymmetric deformable porous membrane preparation process is as follows: 3.5 g PVDF, 10.75 mL acetone and 10.75 mL N, N-dimethylacetamide (DMAC) are stirred at room temperature for 2 h to form a uniform electrospinning solution. The injection speed during electrospinning is set to 0.15 mm / min, the voltage is +9 / -1 kV, the ambient humidity is 36±1% RH, the working time is 80 min, and the rigid polyvinylidene fluoride (PVDF) layer is formed by electrospinning as a rigid porous layer with an average pore size of 2.8 μm. 1.2g PVDF, 0.8g PAN and 14g N,N-dimethylformamide (DMF) were stirred evenly in a water bath at 50-55℃, and then an elastic polyvinylidene fluoride / polyacrylonitrile (PVDF / PAN) layer was directly spun on the original rigid PVDF layer. The injection speed was set to 0.20mm / min, the voltage was +19 / -1kV, the ambient humidity was 39±1%RH, the working time was 30min, and the average pore size of the elastic PVDF / PAN layer was 1.0μm. Both steps of electrospinning process used a 20-gauge needle, the stroke was set to 60mm, the translation speed was 100mm / min, and the receiving speed was 20r / min. The elastic modulus of the rigid PVDF layer obtained was about 97.1MPa, and the elastic modulus of the elastic PVDF / PAN layer was about 9.5MPa.

[0035] Lubricant Krytox 100 was selected as the adaptive functional liquid, which infiltrated the asymmetric deformable porous membrane and the two cooperated to form a control channel for the fluid. The contact angle of lubricant Krytox 100 on PVDF was 51.6° and the contact angle on PVDF / PAN was 50.9°, thus achieving strong wetting and ensuring thermodynamic stability.

[0036] One-way fluid control is related to the ventilation threshold pressure difference on both sides, that is, the greater the threshold pressure difference, the easier it is to achieve one-way fluid control. Figure 2 As shown in the figure, due to the different compressive stress-strain conditions of the rigid PVDF layer and the elastic PVDF / PAN layer, when the gas passes through the fluid unidirectional control unit, the rigid polyvinylidene fluoride (PVDF) layer and the elastic polyvinylidene fluoride / polyacrylonitrile (PVDF / PAN) layer will produce different compression deformations, which will lead to unequal threshold pressures P when passing through different parts. R With P E .

[0037] The pressure threshold is related to the surface chemistry, pore distribution of the porous membrane, pore geometry and the compression of the two membrane parts, such as the thickness ratio T between the elastic PVDF / PAN layer and the rigid PVDF layer. E / T R (PVDF / PAN layer thickness is TE , the thickness of the PVDF layer is T R ) and the blending ratio of PVDF to PAN in the elastic polyvinylidene fluoride / polyacrylonitrile (PVDF / PAN) layer will affect the P E , P R The pressure difference ΔP on both sides affects the result, refer to Figure 3 As shown. Figure 3 (a) It can be seen that as the thickness ratio T E / T R Increase, the pressure threshold is higher than P E / P R Gradually decreases, thickness is greater than T E / T R It is preferably between 0.2 and 2.5 to achieve a more ideal difference effect. In this embodiment, the thickness T E About 40μm, T R About 34μm. Figure 3 (b) It can be seen that the larger the blending ratio PVDF / PAN of PVDF and PAN in the elastic polyvinylidene fluoride / polyacrylonitrile (PVDF / PAN) layer, the larger the pressure difference ΔP. Considering the fiber-based structure and the mechanical properties of the film, the blending ratio of 6:4 is selected in this embodiment.

[0038] Example 2

[0039] By designing the fluid one-way control unit of the first embodiment through the flow loop, an OR gate and an AND gate similar to an electronic diode can be formed, thereby generating a logical relationship between the input gas pressure and the output flow rate. Figure 4 , with one side of the rigid part and the elastic part as the input end and the other side as the output end, different output modes can be achieved by adjusting the input air pressure. Input pressure P R Corresponding to logic 0, input pressure P E Corresponding to logic 1, the flow rate Q is the output, a relatively low value is logic 0, and a relatively high value is logic 1. The corresponding output Q is measured with a gas mass flow meter. The results show that when P is input at any position of the rigid part E When both input values ​​are equal to P, the output is 1, which behaves like a traditional OR gate. A similar setting also applies to AND gates. The results show that only when both input values ​​are equal to P E When , the flow rate Q is relatively high, that is, the output is 1.

[0040] Example 3

[0041] Through simple origami operations, the fluid unidirectional control unit can be folded to achieve different pressure thresholds, thereby realizing multi-valued logic, reference Figure 5 and Figure 6The input logic 0, 1, and 2 correspond to the three folding states: unfolded, half-folded, and three-folded. The other input logic 0, 1, and 2 correspond to the three threshold pressures (low, medium, and high) of the folding state. 1 , P 2 , P 8 ); when the flow rate is lower than 5mL / min, the output is 0; when the flow rate is between 5 and 40mL / min, the output is 1; when the flow rate is higher than 40mL / min, the output is 2. Figure 5 By combining different folding states and input pressures, the direction and flow of the gas can be controlled.

[0042] refer to Figure 7 A differentiated fluid control system includes an input channel 1, a differentiated control unit 2 and multiple output channels A1, A2, and A3; the differentiated control unit 2 is formed by the above-mentioned fluid unidirectional control unit through a folding operation to form multiple control areas in different folding states (the examples in the figure are three parts: plane, folded in half, and folded in three parts), and the multiple control areas in different folding states have different threshold pressures of gas flow through the membrane; the differentiated control unit is arranged between the input channel and the output channel, and the control area and the output channel correspond one to one to achieve differentiated output of different output channels. Specifically, the sealed connection between the differentiated control unit 2 and the input channel and the multiple output channels A1, A2, and A3 can be achieved by the clamp 3.

[0043] Example 4

[0044] This embodiment applies a differentiated fluid control system of a specific folding mode to the joint control of an excavator model, constructs a pneumatic mechanical device controlled by the same multi-valued logic, and as the pressure input gradually increases, the joints of the excavator gradually move.

[0045] A pneumatic mechanical device controlled by the same multi-valued logic, the multi-valued logic used is similar to that of Example 3, with an additional extended input pressure, P 8 High 30kPa, as logic 3. Figure 7 The differential fluid control system shown is gas driven, and the differential control unit 2 here adopts Figure 5 The folding pattern of D5 in the middle is used to make a planar fluid logic gate, forming three gated areas with three different folding states: single layer, double layer and triple layer. An airflow is input at the input channel 1, and the airflow that breaks through the respective threshold pressure can be output from the airflow output ports A1, A2 and A3 through the corresponding control areas. Figure 8 and Fig. 9In the test, the output-motion of the excavator joint is controlled by the accumulated gas flow in the cylinder (syringe). The three movable joints of the excavator are controlled by the gas flow in three syringes respectively, and the three syringe needles (C1, C2 and C3) are connected to the gas output ports A1, A2 and A3 by three rubber tubes B1, B2 and B3 respectively.

[0046] The following describes its action process: Injector C1 is closest to the bucket 4, and its syringe needle is fixed to the top of the stick 5. The piston push rod of C1 is connected to the connecting rod 6 and the rocker 7 that can control the bucket joint, and the needle is connected to the rubber tube B1. When the cylinder gas flow in the injector C1 increases, the piston push rod pushes downward, and the angle α between the bucket 4 and the stick 5 decreases accordingly. Conversely, when the cylinder gas flow in the injector C1 decreases, the piston push rod pulls upward, and the angle α between the bucket 4 and the stick 5 increases accordingly. Injector C2 is located above the excavator boom 8, and its needle end is fixed to the excavator boom angle screw 9. The piston push rod is connected to the top of the stick 5, and the needle is connected to the rubber tube B2. When the cylinder gas flow in the injector C2 increases, the piston push rod pushes the stick 5 upward, so that the angle β between the front end of the boom 8 and the stick 5 decreases. On the contrary, when the cylinder gas flow in the syringe B2 decreases, the piston push rod pulls the boom 5 downward, so that the angle β between the front end of the boom 8 and the boom 5 increases. The syringe C3 is located below the boom 8, and its syringe needle end is fixed on the boom base bracket 10. The piston push rod is connected to the screw 11 that can rotate near the front end of the boom 8 corner, and the needle is connected to the rubber tube B3. When the cylinder gas flow in the syringe C3 increases, the piston push rod pushes the front end of the boom 8 upward, so that the angle ε between the boom 8 and the horizontal plane of the vehicle body 12 increases. On the contrary, when the cylinder gas flow in the syringe C3 decreases, the piston push rod pushes the front end of the boom 8 downward, so that the angle ε between the boom 8 and the horizontal plane of the vehicle body 12 decreases. Due to the distance limit of the cylinder and the increasing pressure, the highest output is limited to logic 2. There are three joints with angles of α, β, and ε, which are controlled by multi-valued logic, and their origami patterns are the same as those in Example 3. As the pressure input gradually increases, the joints of the excavator gradually move. When the input pressure is logic 0, there is no airflow or low airflow at the tail, the excavator is stationary, the joint angle output between the dipper arm 5 and the bucket 4 is α, the angle output between the boom 8 and the dipper arm 5 is β, and the angle output between the boom 8 and the horizontal plane of the vehicle body 12 is ε ( Fig. 9 When the input pressure increases (logic 1), the plane fluid logic gate origami starts to output the accumulated gas flow, controls the piston push rod of the syringe C1 to push down, drives the joint between the bucket 5 and the bucket 4 to output to α 1 ( Fig. 9 When the input pressure increases further (logic 2), the cumulative air flow output of the plane fluid logic grid origami control increases further, and the joint output angle between the arm 5 and the bucket 4 will further expand to the limit α 2, and the folded fluid logic gate origami begins to output the accumulated gas flow, and the piston push rod of the controlled syringe C2 is pushed upward, driving the angle between the boom 8 and the dipper 5 to output to β 1 ( Fig. 9 When the input pressure reaches the highest value (logic 3), the joint output angle between the arm 5 and the bucket 4 controlled by the plane fluid logic grid origami is still α 2 , the cumulative air flow output of the folded fluid logic gate origami control is further increased, and the angle between the boom 8 and the stick 5 is output to β 2 , and the three-fold fluid logic gate origami begins to output cumulative gas flow, controlling the piston push rod of the syringe C3 to push upward, driving the joint between the boom 8 and the horizontal plane of the vehicle body 12 to output to ε 1 ( Fig. 9 Lower left state). When opposite pressure is applied, the excavator returns to its original state. By using this new type of fluid logic gate origami, pneumatic devices can be controlled by a single inlet logic.

[0047] In addition, other mechanical structures with multiple action units can also use the differentiated fluid control system of the present invention as a fluid driving unit to achieve logically programmable differentiated control.

[0048] The above embodiments are only used to further illustrate a fluid one-way control unit and its application of the present invention, but the present invention is not limited to the embodiments. Any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the technical solution of the present invention.

Claims

1. A fluid one-way control unit, Features: It includes an asymmetric deformable porous membrane and an adaptive functional liquid, wherein the adaptive functional liquid at least partially infiltrates the asymmetric deformable porous membrane and the two cooperate to form a control channel for the fluid; wherein the asymmetric deformable porous membrane is composed of a rigid porous layer and an elastic porous layer and forms a rigid part and an elastic part respectively, and the threshold pressure through the rigid part through the control channel is different from the threshold pressure through the elastic part through the control channel, thereby realizing the control of the fluid passing through the membrane.

2. The fluid one-way control unit according to claim 1, Features: The difference in elastic modulus between the rigid porous layer and the elastic porous layer is 9 to 13 times.

3. The fluid one-way control unit according to claim 1, Features: The pore size distribution of the rigid porous layer is between 0 and 5 μm, and the pore size distribution of the elastic porous layer is between 0 and 3 μm.

4. The fluid one-way control unit according to claim 1, Features: The thickness ratio of the elastic porous layer to the rigid porous layer is 1:5 to 5:

2.

5. The fluid one-way control unit according to claim 1, Features: The rigid porous layer is a polyvinylidene fluoride layer, and the elastic porous layer is a polyvinylidene fluoride / polyacrylonitrile layer; the polyvinylidene fluoride layer and the polyvinylidene fluoride / polyacrylonitrile layer are respectively formed by an electrostatic spinning process, and the polyvinylidene fluoride / polyacrylonitrile layer is directly spun on the polyvinylidene fluoride layer.

6. The fluid one-way control unit according to claim 1, Features: The contact angle of the adaptive functional liquid on the rigid porous layer and the elastic porous layer is less than 60°.

7. A differentiated fluid control system based on a fluid unidirectional control unit, Features: It comprises an input channel, a differentiated control unit and a plurality of output channels; the differentiated control unit is a fluid one-way control liquid gating unit as described in any one of claims 1 to 6, which forms a plurality of control areas in different folding states through a folding operation, and the plurality of control areas in different folding states have different fluid transmembrane threshold pressures; the differentiated control unit is arranged between the input channel and the output channel, and the control areas and the output channels correspond one to one to realize differentiated output of different output channels.

8. The differentiated fluid control system according to claim 7, Features: The folding operation includes cutting the asymmetric deformable porous membrane and performing differential folding on different regions. The folding states include single-layer, double-layer and multi-layer formed by no folding, half folding and multiple folding.

9. Use of the fluid one-way control unit according to any one of claims 1 to 6 in gas drive.

10. A pneumatic mechanical device, It is characterized in that It comprises the differentiated fluid control system described in any one of items 7 to 8 and a plurality of action units, wherein the plurality of output channels act on the plurality of action units one by one, and the differentiated actions of the plurality of action units are controlled by controlling the fluid input pressure of the input channel.

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