CN113482893B

CN113482893B - Flexible pump based on dielectric elastic material

Info

Publication number: CN113482893B
Application number: CN202110649740.8A
Authority: CN
Inventors: 夏庆超; 马姝阳; 吴泽亮; 杨灿军
Original assignee: Zhejiang University ZJU
Current assignee: Zhejiang University ZJU
Priority date: 2021-06-10
Filing date: 2021-06-10
Publication date: 2022-04-01
Anticipated expiration: 2041-06-10
Also published as: US20230047195A1; CN113482893A

Abstract

The invention discloses a pump, in particular to a flexible pump based on dielectric elastic materials, which comprises: the flexible pump bag comprises a plurality of tubular flexible films with non-telescopic and fusiform cross sections, the tubular flexible films are arranged in an annular array and are adjacently spliced, the middle section of each tubular flexible film is a filling area and is filled with a liquid medium with high breakdown strength in a saturated mode, and a positive electrode and a negative electrode are fixed on the radial half side surface of the middle section of each tubular flexible film, are respectively positioned on two sides of an axial reference plane of the middle section and are distributed symmetrically; and the rigid end covers are respectively provided with a water inlet and a water outlet and are respectively positioned at the two ends of the flexible pump bag, and the same-side ends of the plurality of tubular flexible films are fixed to the corresponding rigid end covers one by one. It solves the technical problem of providing a flexible hydraulic pump to provide liquid delivery and pressurization. The flexible pump has the characteristics of elasticity, adaptability and shock absorption, can generate large deformation, and is easy to adapt to the environment.

Description

Flexible pump based on dielectric elastic material

Technical Field

The invention relates to a pump, in particular to a flexible pump based on dielectric elastic materials.

Background

Along with the development of the bionics technology, more integrated and refined mechanical technology is more and more emphasized by people. In integrated and refined mechanical equipment, the driving performance is very important. There are very strict requirements for driving reliability, motion consistency, response speed, precision, and the like.

The hydraulic drive is one of important drive modes, has the characteristics of low speed, stability, large transmission power, overload protection capability, flexible transmission arrangement and the like, and a pump is a hydraulic transmission core and has the function of conveying fluid or pressurizing the fluid. The common pump on the market is made of metal materials and is widely applied to the fields of industrial automation and the like.

However, the conventional metal pump has the following problems:

(1) rigid components generally have limited degrees of freedom, and the flexibility of pump movement is limited;

(2) under the influence of working conditions, the metal pump often has the phenomena of corrosion, cavitation erosion, scouring, abrasion and the like, so that equipment fails, and a large amount of parts are paid for by only investing a large amount of funds to purchase a new pump, so that a large amount of funds and materials are wasted;

(3) the metal pump has the advantages of complex structure, large volume, large mass, difficult movement and carrying, and limitation in the application of some precise fields, such as the biomedical field;

(4) the production and manufacturing costs of metals are high.

These problems have resulted in certain limitations in the development of metallic materials in this field.

Disclosure of Invention

The invention aims to solve the defects of the prior art, and the traditional metal pump is improved in material and mechanism, and a flexible hydraulic pump is developed by utilizing the deformation principle of dielectric elastic materials so as to provide the functions of liquid conveying and pressurization.

In order to achieve the above object, the present invention provides a flexible pump based on dielectric elastic material, which comprises: the flexible pump bag comprises a plurality of tubular flexible films with non-telescopic and fusiform cross sections, the tubular flexible films are arranged in an annular array and are adjacently spliced, the middle section of each tubular flexible film is a filling area and is filled with a liquid medium with high breakdown strength in a saturated mode, and a positive electrode and a negative electrode are fixed on the radial half side surface of the middle section of each tubular flexible film, are respectively positioned on two sides of an axial reference plane of the middle section and are distributed symmetrically; and the rigid end covers are respectively provided with a water inlet and a water outlet and are respectively positioned at the two ends of the flexible pump bag, and the same-side ends of the plurality of tubular flexible films are fixed to the corresponding rigid end covers one by one.

The working principle of the flexible pump with the structure is as follows:

when the positive electrodes and the negative electrodes on all the tubular flexible films are simultaneously applied with voltage, the positive electrodes and the negative electrodes are gradually closed under the action of electrostatic force, a liquid medium between the radial half-side film parts covered by the positive electrodes and the negative electrodes is squeezed to flow towards the half sides uncovered by the positive electrodes and the negative electrodes, so that the fusiform cross sections of all the tubular flexible films are bulged to form circular cross sections, the total circumference of the flexible pump bag is reduced because the tubular flexible films are not telescopic, the volume of the inner cavity of the flexible pump bag is reduced, meanwhile, the circumferences of the rigid end covers at two sides are kept unchanged during the contraction of the flexible pump bag, the upper section and the lower section of all the tubular flexible films, which are not filled with the liquid medium, generate axial contraction displacement, and finally, the liquid in the inner cavity of the flexible pump bag is compressed, and flows out from the water outlets of the rigid end covers;

on the contrary, when the positive electrode and the negative electrode are not applied with voltage, the electrostatic force on the positive electrode and the negative electrode disappears instantly, the liquid medium between the radial half-side film parts which are not covered with the positive electrode and the negative electrode returns to the original position under the driving of the liquid pressure, the circular cross sections of all the tubular flexible films gradually return to the fusiform cross sections, the total circumference of the flexible pump bag is increased because the films are not retractable, and simultaneously the upper section and the lower section of all the tubular flexible films which are not filled with the liquid medium generate axial bending displacement synchronously, so that the volume of the inner cavity of the flexible pump bag is increased, the pressure of the inner cavity of the flexible pump bag is reduced, and the liquid flows in from the water inlet of the rigid end cover.

On the basis of the scheme, the invention can also make the following improvements:

the preferred scheme is that the electrode adopts an ion-conductive hydrogel electrode patch. The hydrogel electrode is soft in property, the deformation of the film wrapping the liquid medium is large during the working period of the flexible pump, the soft hydrogel electrode can be well attached to the film, the film is not easily abraded, and the liquid medium in the film is prevented from being leaked outwards.

The preferable scheme is that the liquid medium filled in the non-telescopic tubular flexible film is plant-based oil with high breakdown strength. When the electrostatic force is used, the requirement on the electric field is very high, and a voltage of several kilovolts is usually required to be provided, so that a liquid medium with a high dielectric constant is required to be used, and the leakage of oil liquid after breakdown is avoided.

The preferred scheme is that the one-way valves of the water inlet and the water outlet can adopt a film valve plate with a single-film, double-film or multi-film structure, and the functions of one-way filling and flowing of fluid can be guaranteed while the structure is simplified.

Further, the preferable scheme is improved, the check valves of the water inlet and the water outlet can adopt a valve structure for preventing backflow. There are valve structures in the heart that prevent the reverse flow of blood, the valves open when flowing in the flow direction and close when flowing against the flow direction. The backflow prevention valve is manufactured by referring to the structure principle and is arranged at the water inlet and the water outlet to ensure the unidirectional flow of the fluid. Simple structure, it is convenient to use.

The scheme has the advantages that: first, compared to a metal material, the flexible pump using a flexible material has elasticity, adaptability, and shock absorption characteristics, can generate large deformation, and is easily adaptable to the environment. Secondly, the pump equipment made of flexible materials is light in weight, convenient to carry and move, lower in cost, easy to produce and manufacture, and free of corrosion, cavitation and other phenomena. In addition, when not in use, the flexible pump can be easily stored after the liquid in the inner cavity of the pump bag is discharged.

Drawings

FIG. 1 is a schematic diagram I of the overall structure of a flexible pump when no voltage is applied;

FIG. 2 is a schematic view of the operation principle of the valve structure for preventing backflow in the water inlet;

FIG. 3 is a schematic view of the operation principle of the valve structure for preventing backflow in the water outlet;

FIG. 4 is a schematic diagram illustrating the principle of deformation of a dielectric elastomer;

FIG. 5 is a schematic diagram of the expansion and contraction length of the dielectric elastomer material;

FIG. 6 is a top view of a mid-section of a flexible pump bladder structure when no voltage is applied;

FIG. 7 is a top view of a mid-section of a flexible pump bladder structure when a voltage is applied;

FIG. 8 is a schematic diagram of the overall structure of the flexible pump when a voltage is applied;

fig. 9 is a schematic diagram of the overall structure of the flexible pump when no voltage is applied.

In the figure: the device comprises a water inlet 1, an upper end cover 2, a flexible pump bag 3, a lower end cover 4, a water outlet 5, a valve structure 6, a liquid medium 7, a tubular flexible film 8, a positive electrode 9, a negative electrode 10, an upper section 11 and a lower section 12.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments that can be derived from the embodiments of the present invention by a person of ordinary skill in the art are intended to fall within the scope of the present invention.

As shown in fig. 1, as an embodiment of the present invention, the flexible pump based on dielectric elastic material provided in this embodiment includes a water inlet 1, an upper end cap 2, a non-retractable flexible pump bladder 3, a lower end cap 4 and a water outlet 5; wherein, the upper and lower end covers 2, 4 are respectively arranged at the upper and lower ends of the flexible pump capsule 3 and are connected with the flexible pump capsule 3 in a sealing way.

As shown in figures 2 and 3, a flexible backflow-preventing valve structure 6 is arranged on the edge of the inner part of the water inlet 1, and the structure is similar to the valve structure 6 for preventing the backflow of blood in the heart. When the liquid in the flexible pump capsule 3 is to flow out from the water inlet 1, as shown in fig. 2 (a), the valve is in a closed state, and the water in the flexible pump capsule 3 cannot flow out. When external water is about to enter the interior of the flexible pump capsule 3, as shown in fig. 2 (b), the external pressure is higher than the internal pressure, the valve is in an open state, and external water flow is pumped into the interior of the flexible pump capsule 3. Similarly, a circle of flexible backflow-preventing valve structure 6 is also arranged on the edge inside the water outlet 5. When the external liquid wants to flow into the flexible pump capsule 3, as shown in fig. 3 (a), the valve is in a closed state, and the external liquid cannot enter the interior of the flexible pump capsule 3 from the water outlet 5. When the liquid in the flexible pump bag 3 is about to flow out, as shown in fig. 3 (b), the pressure in the flexible pump bag 3 is higher than the external pressure, the valve is in the open state, and the liquid in the flexible pump bag 3 is pumped out.

As shown in fig. 4, the flexible pump capsule 3 is mainly composed of four parts, a liquid medium 7, a non-stretchable rectangular flexible film, a positive electrode 9, and a negative electrode 10. A flexible pump driven by the deformation principle of a dielectric elastomer requires a high electric field, so the liquid medium 7 is selected from a vegetable-based oil with high breakdown strength. The non-stretchable rectangular flexible film is a biaxially oriented polypropylene film, and the material is excellent in mechanical strength and high in dielectric breakdown strength, so that the reliability in the use process is guaranteed. The positive electrode 9 and the negative electrode 10 are ion-conductive hydrogel electrode patches. The aquogel electrode is softer, and at flexible pump during operation, deformation is great, and the flexible film of the laminating of aquogel electrode ability is not tensile to difficult the wearing and tearing that cause prevents that liquid medium 7 from revealing the phenomenon appears in the film damage. The specific manufacturing process comprises the following steps: firstly, an inextensible rectangular flexible film is sealed by a hot press and a heating metal die to prepare a plurality of tubular flexible films 8 which are annularly arrayed and adjacently spliced and have inextensible fusiform cross sections, the middle section of each tubular flexible film 8 is a filling area, and a gap is reserved on the sealing boundary of each filling area to facilitate the filling of a liquid medium 7. After the liquid medium 7 is saturated, the above-mentioned gap is completely sealed with a heated aluminum strip. Finally, a prefabricated hydrogel electrode is affixed to the half side of the middle section of each tubular flexible membrane 8.

As another embodiment of the present invention, the specific structure of the flexible pump bladder 3 in the structure may also be as shown in fig. 9, and the specific manufacturing process is as follows: firstly, a plurality of non-stretchable tubular flexible films 8 are sealed by using a hot press and a heating metal die, the tubular flexible films 8 are made of polypropylene films, the middle section of each tubular flexible film 8 is a filling area, and a gap is reserved on the sealing boundary of the filling area so as to facilitate the filling of the liquid medium 7. Next, after the liquid medium 7 is saturated and filled, the above-mentioned gap is completely sealed with a heated aluminum strip. Then, the plurality of tubular flexible films 8 are arranged in an annular array, and are subjected to adjacent hot-pressing splicing by adopting a hot press and a heating metal mold again. Finally, a prefabricated hydrogel electrode is affixed to the half side of the middle section of each tubular flexible membrane 8.

The deformation principle of the dielectric elastic material is as follows: when not energized, as shown in fig. 4 (a), the liquid medium 7 is wrapped by a non-stretchable tubular flexible film 8, one half side of the tubular flexible film 8 covers the positive electrode 9 and the negative electrode 10, and the other half side does not cover the electrodes. When a voltage V is applied to the electrodes₂Then, under the action of electrostatic force, the positive and

negative electrodes

9, 10 are gradually closed, and the liquid medium 7 wrapped by the tubular flexible film 8 on the half side covered by the positive and

negative electrodes

9, 10 is squeezed to flow to the half side uncovered by the electrodes. As shown in fig. 4 (b), the originally flat shuttle-shaped cross section gradually bulges under the pressing of the positive and

negative electrodes

9, 10. As shown in fig. 4 (c), when the liquid medium 7 wrapped by the tubular flexible film 8 covered with the positive and

negative electrodes

9, 10 is completely pressed to the half uncovered with the positive and

negative electrodes

9, 10, the cross section becomes circular. After no voltage is applied, the electrostatic force disappears, the liquid pressure on the half side which is not covered by the positive and

negative electrodes

9 and 10 is larger than that on the half side which is covered by the positive and

negative electrodes

9 and 10, the liquid flows from high pressure to low pressure, the liquid medium 7 gradually flows from the half side which is not covered by the positive and

negative electrodes

9 and 10 to the half side which is covered by the positive and

negative electrodes

9 and 10, and the cross section is changed from a circular shape to a flat shuttle-shaped cross section. As shown in FIG. 5, if each length of the tubular flexible film 8 is 2L₀In the unpowered stage, the cross section is flat, and the length of each segment is also approximately 2L₀. At an applied voltage V₂Then, under the action of electrostatic force, the positive and

negative electrodes

9, 10 are closed, the original flat shuttle-shaped cross section is changed into a circular cross section, and the total length of each section of the dielectric elastomer is changed into L due to the inextensible film₀+2L₀And/pi, the total length is reduced. Similarly, the length of each section of the dielectric elastomer is changed back to 2L again under the action of hydraulic pressure after no voltage is applied₀。

As shown in fig. 6, the dielectric elastic material is arranged in a circle to form a flexible and non-retractable pump bag, and the inside of the circle is wrapped with fluid/liquid to be transported or pressurized. As shown in fig. 7, when a voltage is applied, the total length of the dielectric elastomer is reduced, that is, the total circumference of the flexible pump bladder 3 is reduced, according to the principle of deformation of the dielectric elastic material described above, so that the total volume of the flexible pump bladder 3 is contracted. In the same way, when no voltage is applied, based on the above principle, the dielectric elastomer is restored to the original length under the action of hydraulic pressure, that is, the total circumference of the flexible pump bladder 3 is increased, so that the total volume of the flexible pump bladder 3 is increased.

The overall structure of the flexible pump when no voltage is applied is shown in fig. 1. After the voltage is applied, the positive electrode 9 and the negative electrode 10 are gradually closed by the action of the electrostatic force, and the liquid medium 7 wrapped by the non-telescopic tubular flexible film 8 on the half side covered by the positive electrode 9 and the negative electrode 10 is extruded to flow to the half side not covered by the electrode, so that the flat fusiform cross section is bulged to form a circular cross section, as shown in fig. 8. Since the tubular flexible membrane 8 is not collapsible, the overall circumference of the flexible pump bladder 3 is reduced, thereby allowing the volume of the pump bladder lumen to be reduced. Meanwhile, a section of non-telescopic tubular flexible film 8 is respectively reserved at the upper end and the lower end of the liquid filling part of the flexible pump bag 3, and the liquid medium 7 is not filled in the flexible pump bag. Since the perimeter of the upper end cap 2 and the lower end cap 4 is kept constant, the upper section 11 and the lower section 12 of the non-stretchable tubular flexible film 8 are contracted in the axial direction of the pump capsule, and the liquid in the inner cavity of the pump capsule is further compressed. Under the action of the valve structure 6, liquid cannot flow out of the water inlet 1 of the upper end cover 2 and can only be pumped out of the water outlet 5 of the lower end cover 4. When no voltage is applied to the electrodes, the electrostatic force disappears, the pressure of the liquid medium 7 at the half side wrapped by the film which is not covered by the electrodes is greater than the pressure of the liquid medium 7 at the half side wrapped by the film which is covered by the electrodes, the liquid medium 7 flows back to the original position under the driving of hydraulic pressure, so that the circular section is gradually changed back to a flat cross section, the total circumference of the flexible pump bag 3 is increased due to the fact that the film is not stretchable, the volume of the inner cavity surrounded by the pump bag is increased, the pressure of the inner cavity of the pump bag is reduced, liquid cannot flow in from the water outlet 5 under the action of the valve structure 6, and outside water can only be pumped into the inner cavity of the pump bag through the water inlet 1. According to the process, voltage is continuously applied and interrupted, the flexible pump can continuously pump in liquid from the water inlet 1 and pump out the liquid from the water outlet 5, and the transportation and pressurization of the liquid are realized.

The present invention is not limited to the above-mentioned preferred embodiments, and any other products in various forms can be obtained by anyone in the light of the present invention, but any changes in the shape or structure thereof, which have the same or similar technical solutions as those of the present application, should fall within the protection scope of the present invention.

Claims

1. A flexible pump based on a dielectric elastomeric material, comprising:

the flexible pump bag comprises a plurality of tubular flexible films with non-telescopic and fusiform cross sections, the tubular flexible films are arranged in an annular array and are adjacently spliced, the middle section of each tubular flexible film is a filling area and is filled with a liquid medium with high breakdown strength in a saturated mode, and a positive electrode and a negative electrode are fixed on the radial half side surface of the middle section of each tubular flexible film, are respectively positioned on two sides of an axial reference plane of the middle section and are distributed symmetrically;

and the rigid end covers are respectively provided with a water inlet and a water outlet and are respectively positioned at the two ends of the flexible pump bag, and the same-side ends of the plurality of tubular flexible films are fixed to the corresponding rigid end covers one by one.

2. A flexible pump based on dielectric elastic material as claimed in claim 1, wherein said tubular flexible film is a biaxially oriented polypropylene film.

3. A flexible pump based on dielectric elastomer material as claimed in claim 1, wherein said liquid medium is a high breakdown strength vegetable based oil.

4. A dielectrically elastic material-based flexible pump according to claim 1, wherein the positive and negative electrodes are each an ionically conductive hydrogel electrode patch.

5. The dielectric elastic material-based flexible pump as claimed in claim 1, wherein the rigid end cap has a valve structure at both the water inlet and the water outlet.