Reversible electrically controlled adsorption device

Abstract

The present application relates to the field of industrial suction cup, especially to a reversible electrically controlled adsorption device based on polyvinyl chloride dielectric gel, comprising a cover body, the upper end of the cover body is an upper cover, the lower end is a cover opening, the inner wall of the cover body is circumferentially provided with an anode, the cover opening is closed by an adsorption layer with electroactive deformation, the upper cover of the cover body, the inner wall of the cover body and the inner side of the adsorption layer form an adsorption cavity, the outer side surface of the adsorption layer is provided with a cathode layer which can deform with the adsorption layer, and a sealing ring is arranged on the outer side of the adsorption layer along the edge of the cover opening. The present application combines the electroactive deformation material with the electric field skillfully, realizes the accurate control of the adsorption process, adjusts the adsorption force and has simple structure, which has significant technical effect and wide application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of industrial suction cups, and particularly relates to a reversible electrically controlled adsorption device based on polyvinyl chloride dielectric gel. BACKGROUND

[0002] In the fields of robots, industrial automation and aerospace, end effectors are usually used to transport objects. In view of the problem that traditional rigid manipulators / claws have great damage to target objects, people have designed various suction cup devices to grasp large-area objects, and good results have been achieved.

[0003] At present, common adsorption type end grippers include pneumatic suction cups, magnetic suction cups, electrostatic suction cups and the like. For example, a vacuum suction cup has a simple structure, but is driven by vacuum negative pressure, needs to be attached to a gas pump, and has problems of bulky size, poor flexibility and difficulty in miniaturization. For another example, a magnetic suction cup uses magnetic response materials and an external magnetic field to realize adsorption and desorption, and can provide good adsorption performance, but the assembly equipment required by the magnetic control suction cup is complex and cumbersome, a relatively bulky electromagnetic generator is needed, and the magnetic control suction cup has great limitations in actual use. An electrostatic suction cup is based on the principle of electrostatic adsorption, and requires that the surface of the adsorbed object has conductive properties, but the adsorption force generated by the electrostatic suction cup is very small and cannot meet the adsorption requirements. SUMMARY

[0004] The present application aims to provide a reversible electrically controlled adsorption device with strong adsorption force and simple structure.

[0005] To solve the above problems, the present application provides a reversible electrically controlled adsorption device, which comprises a cover body, the upper end of the cover body is an upper cover, the lower end is a cover opening, the inner wall of the cover body is circumferentially provided with an anode, the cover opening is closed by an adsorption layer with electrochromic deformation, the upper cover of the cover body, the inner wall of the cover body and the inner side of the adsorption layer form an adsorption cavity, the outer side surface of the adsorption layer is provided with a cathode layer which can deform with the adsorption layer, and a sealing ring is arranged on the outer side of the adsorption layer along the edge of the cover opening.

[0006] Beneficial effects: (1) The present application adopts an adsorption layer with electro-deformation characteristics as a key component, when the device is attached to the surface of the target object, the adsorption layer, the cover opening and the surface of the target object form a sealed space. The adsorption layer can change in volume or shape under the action of an electric field. When a voltage is applied, an electric field is formed between the anode and the cathode, the electric field induces the negatively charged substances in the adsorption layer to migrate to the positively charged anode, forming a negative charge enrichment layer near the anode, and attracting the anode, and then driving the adsorption layer to creep and deform along the anode on the cover wall (i.e. the adsorption layer is recessed into the adsorption cavity), thus the volume of the adsorption cavity is reduced, the sealed space is increased to produce negative pressure, and the adsorption of the target object is realized. After power off, the adsorption layer can quickly recover to the initial state, and then the cover body and the target object are separated. This electrically controlled adsorption effect not only has fast response speed, but also has high control accuracy, and can realize fast and reversible adsorption operation.

[0007] (2) The present application sets a sealing ring along the edge of the cover opening outside the adsorption layer, which closely cooperates with the adsorption layer, effectively prevents the interference of the external environment and the leakage of the internal gas, and ensures the sealing and stability of the adsorption cavity during the working process, and improves the adsorption efficiency.

[0008] (3) The present application can accurately control the deformation degree of the adsorption layer by adjusting the voltage size and polarity applied on the electrode plate, and then control the volume change of the adsorption cavity. This reversible control mode makes the device have great application value in occasions where the adsorbed substances need to be frequently replaced or released.

[0009] The present application combines the electro-deformation material with the electric field skillfully, realizes the accurate control of the adsorption process, can adjust the adsorption force, and has simple structure, significant technical effect and wide application prospect.

[0010] Further, the adsorption layer is a layered structure made of polyvinyl chloride dielectric gel, and the outer side is coated with a pre-oxidized eutectic gallium-indium alloy layer as a cathode layer; the anode is a cylindrical structure made of conductive copper mesh.

[0011] Under the action of electric field, the small molecule of dibutyl adipate in the polyvinyl chloride dielectric gel migrates to the anode, forming a negative charge rich layer near the anode side, and then triggering the deformation of the adsorption layer to the anode (i.e. the adsorption layer is concave to the adsorption cavity), so as to realize more efficient adsorption; the anode is a cylindrical structure made of conductive copper mesh, which not only has excellent conductivity, can ensure uniform distribution of electric field and effective transmission to the polyvinyl chloride dielectric gel layer, but also provides good mechanical support and flexibility, so that the deformation process of the adsorption layer can be closely attached to the anode, making the concave deformation more stable and reliable; and the pre-oxidized eutectic gallium-indium alloy as the cathode layer, this alloy has the characteristics of easy stretching (modulus almost zero), low and stable resistance (almost zero resistance change when stretched), especially after pre-oxidation treatment, the coatability and bonding stability with the surface of the polyvinyl chloride dielectric gel are improved, so that the cathode electrode can deform adaptively with the deformation of the adsorption layer, further improving the adsorption efficiency.

[0012] Further, the sealing ring is a polyvinyl chloride dielectric gel ring and is bonded to the edge of the cover opening by a polyvinyl chloride dielectric gel liquid, so that the sealing ring is tightly fixed with the cover opening.

[0013] Further, the mass fraction of the polyvinyl chloride dielectric gel is as follows:

[0014] Polyvinyl chloride polymer 1 part;

[0015] Dibutyl adipate 1-15 parts;

[0016] Tetrahydrofuran 10-30 parts.

[0017] Further, the mass fraction of the polyvinyl chloride dielectric gel is as follows: polyvinyl chloride polymer 1 part, dibutyl adipate 6 parts, tetrahydrofuran 15 parts, the polyvinyl chloride dielectric gel under this ratio has smaller modulus and larger dielectric constant; or polyvinyl chloride polymer 1 part, dibutyl adipate 1 part, tetrahydrofuran 10 parts, the polyvinyl chloride dielectric gel under this ratio has larger modulus, smaller dielectric loss and better breakdown resistance; or polyvinyl chloride polymer 1 part, dibutyl adipate 15 parts, tetrahydrofuran 30 parts, the polyvinyl chloride dielectric gel under this ratio has smaller modulus and stronger deformation ability.

[0018] Further, the pre-oxidized eutectic gallium-indium liquid alloy layer is obtained by stirring the eutectic gallium-indium liquid alloy, then introducing air to oxidize the gallium metal (generate oxidant) to obtain a paste, and then coating the paste on the surface of the adsorption layer. The presence of oxidized gallium converts the easily flowing eutectic gallium-indium liquid alloy into a high-stability paste. The cathode layer formed in this way not only has high conductivity and negligible additional stiffness, but also has good electrical stability during cyclic driving.

[0019] Further, the cover body is a conical cover with narrow upper part and wide lower part, and the anode is a conical mesh cover with narrow upper part and wide lower part, so that the conical mesh cover can be supported during adsorption.

[0020] Further, the lower end of the anode contacts the adsorption layer, so that the distance between the anode and the cathode layer is small, and the electric field strength formed between the anode and the cathode layer is large under the condition that the electric potential difference is unchanged. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 Fig. 1 is a schematic diagram of the three-dimensional structure of the reversible electrically controlled adsorption device according to Embodiment 1 of the present application;

[0022] Figure 2 Fig. 1 is a schematic diagram of the three-dimensional structure of the reversible electrically controlled adsorption device according to Embodiment 1 of the present application;

[0023] Figure 3 Fig. 1 is a schematic diagram of the three-dimensional structure of the reversible electrically controlled adsorption device according to Embodiment 1 of the present application;

[0024] Figure 4 Fig. 1 is a schematic diagram of the three-dimensional structure of the reversible electrically controlled adsorption device according to Embodiment 1 of the present application;

[0025] Figure 5 Fig. 1 is a schematic diagram of the three-dimensional structure of the reversible electrically controlled adsorption device according to Embodiment 1 of the present application;

[0026] Figure 6 Fig. 1 is a schematic diagram of the three-dimensional structure of the reversible electrically controlled adsorption device according to Embodiment 1 of the present application; DETAILED DESCRIPTION

[0027] The reference signs in the drawings of the specification include: upper cover 1, conical mesh cover 2, first wire 3, adsorption layer 4, sealing ring 5, and second wire 6.

[0028] (I) Embodiment 1

[0029] As shown in Fig. 1, the reversible electrically controlled adsorption device according to the present application comprises a cover body with narrow upper part and wide lower part and in conical shape, an upper cover 1 with closed upper end and open lower end, and a through hole formed in the upper cover. Figures 1-3

[0030] A conical mesh cover 2 with narrow upper part and wide lower part made of conductive copper wire is attached to the inner wall of the cover body, and the conical mesh cover 2 is an anode and is connected to the first wire 3. The first wire 3 is connected to the positive electrode of the power supply after passing through the through hole.

[0031] The adsorption layer 4 made of polyvinyl chloride dielectric gel seals the cover opening, and the upper cover 1 of the cover body, the inner wall of the cover body, and the inner side of the adsorption layer 4 form an adsorption cavity.

[0032] ​The outer side of the adsorption layer 4 is coated with a pre-oxidized eutectic gallium-indium alloy as a cathode layer, and a sealing ring 5 made of polyvinyl chloride dielectric gel is adhered to the outer side of the adsorption layer 4 along the edge of the cover opening by a polyvinyl chloride dielectric gel liquid. The cathode layer is soldered to a second conductive wire 6, which is connected to the negative electrode of a power supply after passing through the sealing ring. Because the sealing ring 5 has a certain thickness, when the reversible electrically controlled adsorption device contacts the surface of the target object, a sealed space is formed between the adsorption layer 4 and the target object.

[0033] The ratio and preparation method of the polyvinyl chloride dielectric gel and the pre-oxidized eutectic gallium-indium alloy in this embodiment 1 are as follows:

[0034] The polyvinyl chloride dielectric gel: the mass fraction of the raw materials is polyvinyl chloride polymer: dibutyl adipate: tetrahydrofuran = 1:6:15. The raw materials are blended and stirred uniformly to obtain a polyvinyl chloride dielectric gel stock solution, which is then poured into the corresponding mold. After the evaporation of tetrahydrofuran, the adsorption layer 4 and the sealing ring 5 are obtained.

[0035] The pre-oxidized eutectic gallium-indium alloy: the mass fraction of the liquid alloy raw materials is gallium: indium = 75:25. The eutectic gallium-indium liquid alloy is stirred for 60 minutes using a magnetic stirrer to form a paste, which is then coated on the outer side of the adsorption layer 5.

[0036] As shown in Figure 3 After power is turned on, the adsorption layer 5 (polyvinyl chloride dielectric gel) migrates under the action of the electric field, and the dibutyl adipate small molecules inside the adsorption layer 5 migrate towards the anode to form a negative charge enrichment layer near the anode side, which further causes the adsorption layer to deform towards the anode (i.e., the adsorption layer 5 is recessed into the adsorption cavity), achieving adsorption. After power is turned off, the electric field disappears, and the adsorption layer 5 returns to its original position, achieving desorption.

[0037] (II) Embodiment 2, Embodiment 3, Comparative Example 1, Comparative Example 2, and Comparative Example 3

[0038] Embodiments 2 and 3 have the same structure, adsorption layer material, and cathode material as Embodiment 1, but the specific ratio and preparation method are different. Comparative Examples 1, 2, and 3 have the same structure as Embodiment 1, but the materials / preparation methods of the adsorption layer and the cathode are different. The specific details are as follows:

[0039]

[0040]

[0041] (III) Performance Test

[0042] (1) Adsorption layer elastic modulus test

[0043] The adsorption layers in Examples 1-6 were cut to the same size (length 10 mm x width 10 mm), and each was subjected to uniform stretching using a universal testing machine, and the stress-strain curve was calculated and plotted, wherein the stress and strain were calculated as follows:

[0044] Stress (σ): refers to the force per unit area, and the calculation formula is σ = F / A, wherein F is the force acting on the material, and A is the contact area of the force, which describes the strength of the external force on the material.

[0045] Strain (ε): refers to the relative deformation of the material when subjected to an external force, and the calculation formula is ε = ΔL / L, wherein ΔL is the deformation of the material in the direction of the force, and L is the original length of the material, which describes the degree of deformation of the material under the action of the external force;

[0046] The slope of the 0-10% section of the stress-strain curve was calculated to obtain the elastic modulus as follows:

[0047] Elastic modulus of the adsorption layer (kPa) Example 1 0.077 MPa Example 2 0.423 MPa Example 3 0.039 MPa Comparative Example 1 0.169 MPa Comparative Example 2 0.077 MPa Comparative Example 3 0.077 MPa

[0048] Note: Examples 1, Comparative Example 2, and Comparative Example 3 used the same polyvinyl chloride dielectric gel, so the experimental results were completely consistent.

[0049] From the above table, the elastic modulus is: Example 2 > Comparative Example 1 > Example 1 = Comparative Example 2 = Comparative Example 3 > Example 3. In theory, the greater the elastic modulus, the more difficult the deformation, and the smaller the adsorption force, which is further verified in subsequent performance tests.

[0050] (2) Tensile-conductive performance test

[0051] The adsorption layer in Example 1 was selected as the reference sample, the adsorption layer prepared in Example 1 (which had been coated with the cathode layer in Example 1) was used as Sample 1, and the adsorption layer prepared in Comparative Example 3 (which had been coated with the cathode layer in Comparative Example 3) was used as Sample 2.

[0052] The samples 1 and 2 (both with a size of length 10 mm x width 10 mm) were stretched at room temperature using a universal tensile testing machine, conductive tape was pasted on both ends and connected to a digital source meter, and the resistance during stretching was tested using the digital source meter. Record: (1) record the data every 10% strain, including the stretching and recovery stages, and plot the strain-resistance change curve as Figure 4 , the resistance of Sample 1 and Sample 2 with respect to the stretching strain can be obtained; (2) the stress-strain curve is plotted, and the elastic modulus of Sample 1 and Sample 2 is obtained, together with the elastic modulus of the reference sample, to form an elastic modulus graph, the results of which are shown in Figure 5 .

[0053] From Figure 4As can be seen, Sample 1 (coated with a pre-oxidized eutectic gallium-indium alloy) exhibits minimal resistance change under 100% strain, with the resistance curves during recovery and stretching nearly overlapping, indicating stable resistance and resistance to external deformation. Sample 2 (coated with carbon paste) exhibits significant resistance change under 100% strain, with the resistance curves during recovery and stretching not overlapping. This suggests that tensile deformation causes resistance changes in the carbon paste electrode, indicating poor stretch resistance and susceptibility to external deformation.

[0054] Depend on Figure 5 It can be seen that the elastic modulus of sample 1 increased by 0.044 MPa compared with the reference sample (not coated with any material), and that of sample 2 increased by 0.095 MPa compared with the reference sample, indicating that the modulus increased less after the pre-oxidized eutectic gallium-indium alloy was coated with polyvinyl chloride dielectric gel, while the modulus increased more after coating with carbon paste.

[0055] In summary, the pre-oxidized eutectic gallium-indium alloy has stable electrical properties and extremely low added modulus. It is superior to carbon paste when coated on polyvinyl chloride dielectric gel as an electrode, ensuring that the polyvinyl chloride dielectric gel layer can maintain stable adsorption performance during the self-adaptation process along the anode.

[0056] (3) Conductivity test

[0057] The adsorption layer coated with the eutectic gallium-indium liquid alloy was cut (length 10 mm × width 10 mm), and the resistance of the eutectic gallium-indium liquid alloy (cathode layer) was measured using a digital source meter, and the conductivity was calculated.

[0058] The conductivity (ρ) is calculated as follows: ρ = RL / S, where R is the resistance in Ω; L is the length of the eutectic gallium-indium liquid alloy in mm; S is the cross-sectional area of ​​the eutectic gallium-indium liquid alloy in mm 2 The test results are shown in the following table:

[0059] Sample Pre-oxidized eutectic gallium-indium alloy conductivity (unit: S / m) Example 1 3.09 x 10 6 ]] Example 2 3.17 x 10 6 ]] Example 3 3.20 x 10 6 ]] Comparative Example 1 <![CDATA[3.09×10 6 ]]> Comparative Example 2 3.23 x 10 6 ]]

[0060] Note: Example 1 and Comparative Example 1 use exactly the same pre-oxidized eutectic gallium-indium liquid alloy, so the experimental results are completely consistent.

[0061] As can be seen from the table above, the conductivity results are as follows: Example 1 / Comparative Example 1 > Example 2 > Example 3. This is because the pre-oxidation times for the eutectic gallium-indium alloy in Examples 1, 2, and 3 were 60 minutes, 40 minutes, and 20 minutes, respectively. As the stirring time decreases, the non-conductive gallium oxide content decreases, and the conductivity becomes stronger, resulting in higher conductivity. Comparative Example 1, using the same 60-minute pre-oxidation eutectic gallium-indium alloy as in Example 1, achieves the same conductivity as Example 1.

[0062] Comparative Example 2 uses eutectic gallium indium alloy without any mechanical stirring, and has the highest electrical conductivity, but the subsequent performance test results show that the adsorption force of Comparative Example 2 is 0, indicating that the eutectic gallium indium alloy without pre-oxidation cannot form an electrode layer on the surface due to insufficient adhesion, and therefore cannot be used. On the other hand, from the comparison of the absolute values of the sample conductivity, although stirring reduces the electrical conductivity, the actual decrease is very limited, and even between Example 1 with the longest stirring time and Comparative Example 2 without any stirring, the difference is only 0.14 x 10 6 .

[0063] 2. Adsorption force performance test

[0064] Example 1 was subjected to adsorption formation under a voltage of 0-900V, and the test method was as follows: the upper cover of the cover body was fixed with the upper clamp of the universal tensile testing machine, and a glass plate was horizontally fixed at the lower clamp as the target adsorbent. After power on, the universal tensile testing machine was used to pull at a constant speed, and the adsorption force was measured. As shown in Figure 6 , the adsorption force is different under different voltages, and increases gradually with the increase of voltage. Among them, at the maximum voltage of 900V, the adsorption force can reach 0.46MPa, which is about the weight of 4 eggs or a middle school textbook, indicating that the adsorption force of the suction cup meets the adsorption needs in production and life. When the electric field is broken down, the maximum adsorption force is reached, so the upper limit of the voltage should be controlled during use.

[0065] Examples 2-3 and Comparative Examples 1-3 were assembled into corresponding reversible electrically controlled adsorption devices in the same way, and their maximum adsorption forces were measured. The test results are as follows:

[0066] Maximum adsorption force (unit: MPa) Example 1 0.46 MPa Example 2 0.33 MPa Example 3 0.12 MPa Comparative Example 1 0 Comparative Example 2 0 Comparative Example 3 Cathode open circuit under external pressure, unstable conductivity, unable to measure

[0067] As can be seen from the above table, Examples 1, 2 and 3 all use polyvinyl chloride dielectric gel as the adsorption layer and pre-oxidized eutectic gallium indium alloy as the cathode, and have significant adsorption force. The three examples show different adsorption forces due to different proportions, with Example 1 > Example 2 > Example 3. According to the material experiment, the adsorption layer of Example 1 has low elastic modulus and is easy to adsorb, so the adsorption force is the largest. The adsorption layer of Example 2 has high elastic modulus and is difficult to deform, so the adsorption force is lower than that of Example 1. The adsorption layer of Example 3 has the lowest elastic modulus, but the polyvinyl chloride polymer content in the adsorption layer is low, and the dielectric constant of the whole material is small, which leads to easy breakdown and the smallest maximum adsorption force.

[0068] Comparative Example 1 uses silica gel as the adsorption layer, and has no adsorption effect, so it has no adsorption force. Comparative Example 2 uses a eutectic gallium-indium alloy that has not been subjected to any mechanical stirring, and because of insufficient adhesion, it cannot form an electrode layer on the surface of the adsorption layer, so it cannot be used as an electrode. Comparative Example 3 uses carbon paste coating, which is prone to open circuit, and cannot be measured.

[0069] The above is only an embodiment of the present application, and common technical solutions and / or characteristics in the scheme are not described in detail. It should be noted that, for those skilled in the art, without departing from the technical solutions of the present application, a number of modifications and improvements can be made, which should also be considered as the protection scope of the present application, and these will not affect the effect and practicality of the patent. The protection scope claimed by the present application should be subject to the content of its claims, and the specific embodiments and the like in the specification can be used to explain the content of the claims.

Claims

1. A reversible electrically controlled adsorption device, comprising a housing, wherein the upper end of the housing is an upper cover and the lower end is a housing opening, characterized in that: An anode is arranged on the circumference of the inner wall of the cover, and the cover opening is closed by an adsorption layer with electro-deformation. The cover upper cover, the inner wall of the cover and the inner side of the adsorption layer together form an adsorption cavity; a cathode layer that can deform with the adsorption layer is provided on the outer surface of the adsorption layer, and a sealing ring is provided on the outside of the adsorption layer along the edge of the cover opening, and the lower end of the anode is in contact with the adsorption layer.

2. The reversible electrically controlled adsorption device according to claim 1, characterized in that: The adsorption layer is a layered structure made of polyvinyl chloride dielectric gel, and the outer side of the adsorption layer is coated with a pre-oxidized eutectic gallium-indium alloy layer as a cathode layer; the anode is a cylindrical structure made of a conductive copper mesh.

3. The reversible electrically controlled adsorption device according to claim 2, characterized in that: The sealing ring is a polyvinyl chloride dielectric gel ring and is bonded to the edge of the cover opening by polyvinyl chloride dielectric gel liquid.

4. The reversible electrically controlled adsorption device according to claim 3, characterized in that: The mass fractions of the polyvinyl chloride dielectric gel are as follows: 1 part of polyvinyl chloride polymer; 1-15 parts of dibutyl adipate; 10 to 30 parts of tetrahydrofuran.

5. The reversible electrically controlled adsorption device according to claim 4, characterized in that: The mass fractions of the polyvinyl chloride dielectric gel are as follows: 1 part of polyvinyl chloride polymer; 6 parts of dibutyl adipate; 15 parts of tetrahydrofuran.

6. The reversible electrically controlled adsorption device according to claim 4, characterized in that: The mass fractions of the polyvinyl chloride dielectric gel are as follows: 1 part of polyvinyl chloride polymer; 1 part of dibutyl adipate; 10 parts of tetrahydrofuran.

7. The reversible electrically controlled adsorption device according to claim 4, characterized in that: The mass fractions of the polyvinyl chloride dielectric gel are as follows: 1 part of polyvinyl chloride polymer; 15 parts of dibutyl adipate; 30 parts of tetrahydrofuran.

8. A reversible electrically controlled adsorption device according to any one of claims 5 to 7, characterized in that: The pre-oxidized eutectic gallium-indium alloy layer is formed by stirring the eutectic gallium-indium liquid alloy, introducing air to oxidize the gallium metal to obtain a paste, and then coating the paste on the surface of the adsorption layer.

9. The reversible electrically controlled adsorption device according to claim 8, characterized in that: The cover body is a conical cover that is narrow at the top and wide at the bottom, and the anode is a conical cylindrical mesh cover that is narrow at the top and wide at the bottom.

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