CN113541524A

CN113541524A - Friction nanometer generator based on suspension sliding type charge self-excitation

Info

Publication number: CN113541524A
Application number: CN202110881715.2A
Authority: CN
Inventors: 胡陈果; 刘文林; 龙梨
Original assignee: Chongqing University
Current assignee: Chongqing University
Priority date: 2021-08-02
Filing date: 2021-08-02
Publication date: 2021-10-22
Anticipated expiration: 2041-08-02
Also published as: CN113541524B

Abstract

The invention discloses a friction nano generator based on suspension sliding type charge self-excitation, which comprises a TENG and a charge self-excitation system, wherein the charge self-excitation system is used for generating an excitation voltage so as to accumulate TENG charges; the TENG comprises a stator and a rotor, and an air gap exists between the stator and the rotor; the output end of the stator is connected with the input end of the charge self-excitation system, and the output end of the charge self-excitation system is connected with the input end of the rotor. The output charges are continuously and automatically increased through positive feedback between the rotor electrode and the stator electrode so as to improve the output power, and meanwhile, through the design of a suspension structure, the problem of contact wear is effectively avoided, and the service life of a device is prolonged.

Description

Friction nanometer generator based on suspension sliding type charge self-excitation

Technical Field

The invention relates to the technical field of generators, in particular to a friction nanometer generator based on suspension sliding type charge self-excitation.

Background

The use of distributed energy sources has attracted considerable attention from countries around the world. Triboelectric nanogenerators (TENG) have been demonstrated to be a more efficient distributed energy harvesting strategy based on triboelectric and electrostatic induction coupling effects, such as in the harvesting of mechanical energy in human motion, breeze, vibration, etc., to provide energy to personal/small electronic devices. Because TENG has the outstanding advantages of low cost, simple structure, various materials, high flexibility, strong adaptability and the like, the TENG has great application potential in the aspects of biosensing, artificial intelligence, high-voltage application, blue energy and the like.

TENG is largely limited in its progress toward practical applications and commercialization by the fact that its output power is in quadratic proportion to its friction surface charge density. For sliding TENG, contact friction can cause friction surface heat loss and wear, thereby reducing TENG surface charge density, affecting its output performance. The wear is generally delayed by adding interface lubricating oil, but the wear cannot be effectively avoided, and the driving force is increased, so that the micro-energy collection is not facilitated. Non-contact suspended slip mode TENG has high durability and nearly 100% theoretical conversion efficiency (zero friction loss), can easily capture slight kinetic energy, showing TENG's greatest potential in commercial processes. However, the pre-existing charges on the sensing medium layer of the non-contact TENG can decay rapidly, resulting in very small output, so that the charge density and output power of the non-contact TENG need to be improved significantly by charge supplement, mode automatic switching and the like, but the current electrical output of the non-contact TENG still presents a great challenge to meet the requirements of practical application. Therefore, there is a need to invent a new structure friction nano-generator with high durability and high output performance, which can realize wider and more effective micro-energy collection and application.

Disclosure of Invention

Aiming at the problem that the friction generator in the prior art is low in durability and output power, the invention provides a friction nano generator based on suspension sliding type charge self-excitation, the output charge is continuously and self-increased through positive feedback between a rotor electrode and a stator electrode so as to improve the output power, and meanwhile, through the design of a suspension structure, the problem of contact abrasion is effectively avoided, and the service life of a device is prolonged.

In order to achieve the purpose, the invention provides the following technical scheme:

a friction nano-generator based on suspension slip type charge self-excitation comprises a TENG and a charge self-excitation system, wherein the charge self-excitation system is used for generating an excitation voltage so as to accumulate TENG charges; the TENG comprises a stator and a rotor, and an air gap exists between the stator and the rotor; the output end of the stator is connected with the input end of the charge self-excitation system, and the output end of the charge self-excitation system is connected with the input end of the rotor.

Preferably, the mover includes a first hard substrate 1, a first insulating dielectric film 2, and a metal induction electrode 3, the first insulating dielectric film 1 and the metal induction electrode 3 are respectively disposed on a lower surface of the first hard substrate 1 with a gap between the first insulating dielectric film 2 and the metal induction electrode 3, and a lower surface of the metal induction electrode 3 is further covered with a second insulating dielectric film 4.

Preferably, the first insulating dielectric film 2 is made of an electret material, and the second insulating dielectric film 4 is made of a nylon film.

Preferably, the size of the second dielectric insulating film 4 is larger than the size of the metal induction electrode 3.

Preferably, the stator comprises a second hard substrate 8, a first electrode 6, a second electrode 7 and a third insulating dielectric film 5, wherein the first electrode 6 and the second electrode 7 are respectively arranged on the upper surface of the second hard substrate 8, and the upper surfaces of the first electrode 6 and the second electrode 7 are covered with the third insulating dielectric film 5.

Preferably, the third insulating dielectric film 5 is a nylon film.

Preferably, the charge self-excitation system comprises a self-voltage-doubling rectifying circuit and a high-voltage-resistant rectifying diode which are connected in series, and the self-voltage-doubling rectifying circuit comprises the following specific circuits:

a first electrode on the stator is connected with one end of a first capacitor through a first input end, a second electrode on the stator is connected with the anode of a first diode and one end of a fourth capacitor through a second input end respectively, the cathode of the first diode and the other end of the first capacitor are connected in parallel and then connected with the anode of a second diode and one end of a second capacitor respectively, the cathode of the second diode and the other end of the fourth capacitor are connected in parallel and then connected with the anode of a third diode and one end of a fifth capacitor respectively, the cathode of the third diode and the other end of the second capacitor are connected in parallel and then connected with the anode of the fourth diode and one end of the third capacitor respectively, the cathode of the fourth diode and the other end of the fifth capacitor are connected in parallel and then connected with the anode of a fifth diode, the cathode of the fifth diode and the other end of the third capacitor are connected in parallel and then connected with the anode of a rectifier diode, and the cathode of the rectifier diode is connected with an output end.

Preferably, the relationship between the excitation voltage generated by the charge self-excitation system and the TENG charge accumulation Q is as follows:

in formula (1), Q represents charge accumulation of TENG; d1 is the distance, ε, between the second and third insulating dielectric films₀Is the vacuum dielectric constant; s is the area of the metal induction electrode on the mover, V_ERepresenting the excitation voltage generated by the charge self-excitation system.

Preferably, the TENG charge accumulation maximum charge density Q_MaxSatisfies the following conditions:

in formula (2), P represents the pressure of the gas; d2 is the distance between the second electrode on the stator and the metal sensing electrode on the mover; epsilon₀Is the vacuum dielectric constant; s is the area of the metal induction electrode on the rotor; a and B are constants determined by the composition and pressure of the gas, and A is 2.87X 105V (atm. m) at a standard atmospheric pressure of 101kPa^-1And B is 12.6.

Preferably, the arrangement mode between the stator and the rotor comprises a circumferential radioactive arrangement, a linear arrangement or a curved arrangement, so as to form a friction nano-generator capable of collecting rotation or sliding energy.

In summary, due to the adoption of the technical scheme, compared with the prior art, the invention at least has the following beneficial effects:

the suspension sliding type charge self-excitation friction generator is novel and reasonable in design, simple in structure, low in cost and wide in application scene. By adopting the combination of a suspension sliding type structure and a self-voltage-doubling rectifying circuit design, the generator can quickly generate high excitation voltage and quickly accumulate charges; the insulating dielectric film on the surface of the electrode can effectively reduce the attenuation of charges on the electrode and avoid air breakdown, thereby realizing larger energy output.

Due to the design of the suspension structure, the contact friction resistance is greatly reduced, the energy conversion efficiency is improved, the surface of the dielectric film is not abraded, and the service life of the generator is prolonged to the maximum extent. The design of active cell and stator is nimble changeable, can warp into the rotary type for directly collect the rotation energy, and electrode quantity and size all can be adjusted and different demands can be realized. The suspension slip type charge self-excitation friction generator can effectively collect breeze energy in the environment in a normal environment, and has certain potential in the aspects of driving electronic equipment, self-powered systems and the like.

Description of the drawings:

fig. 1 is a structural schematic diagram of a friction nano-generator based on suspension-slip charge self-excitation according to an exemplary embodiment of the invention.

Fig. 2 is a circuit schematic diagram of a charge self-energizing system according to an exemplary embodiment of the invention.

Fig. 3 is a schematic diagram of the accumulation of operating charge of a friction nanogenerator based on suspension slip type charge self-excitation according to an exemplary embodiment of the invention.

Fig. 4 is a comparison diagram of dynamic output charge density curves of a friction generator based on space charge accumulation under different operating conditions according to an exemplary embodiment of the present invention.

Fig. 5 is a schematic top view of a rotary generator according to an exemplary embodiment of the present invention.

FIG. 6 is a schematic representation of the output performance of a friction generator based on space charge accumulation according to an exemplary embodiment of the present invention.

Fig. 7 shows the charge output of a friction generator based on space charge accumulation under different wind speeds according to an exemplary embodiment of the present invention.

Detailed Description

The present invention will be described in further detail with reference to examples and embodiments. It should be understood that the scope of the above-described subject matter is not limited to the following examples, and any techniques implemented based on the disclosure of the present invention are within the scope of the present invention.

In the description of the present invention, it is to be understood that the terms "longitudinal", "lateral", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", and the like, indicate orientations or positional relationships based on those shown in the drawings, and are used merely for convenience of description and for simplicity of description, and do not indicate or imply that the referenced devices or elements must have a particular orientation, be constructed in a particular orientation, and be operated, and thus, are not to be construed as limiting the present invention.

As shown in fig. 1, the present invention provides a friction nano-generator based on suspension-slip charge self-excitation, which comprises a suspension-slip TENG with a charge accumulation electrode and a charge self-excitation system.

The TENG comprises a rotor and a stator, wherein the rotor slides relative to the stator, the stator can be fixed and move, the rotor and the stator are mutually matched, and the electrostatic induction effect is utilized to generate alternating current output to provide electric energy for a load.

The edge of stator and active cell sets up the ya keli gasket that 0.35mm is thick to form the air gap, and then constitute floated sliding structure, can effectually avoid contact wear, furthest extension device's life. Meanwhile, due to the non-contact structure of the stator and the rotor, the running resistance of TENG is small, the required driving force is small, and the TENG can be used for effectively collecting breeze energy in the environment.

The mover includes a first hard substrate 1, a first insulating dielectric film 2 and a metal induction electrode 3, the first insulating dielectric film 2 and the metal induction electrode 3 are respectively disposed on the lower surface of the first hard substrate 1 with a gap between the first insulating dielectric film 2 and the metal induction electrode 3, and the lower surface of the metal induction electrode 3 is further covered with a second insulating dielectric film 4.

In this embodiment, the first dielectric film 2 can be made of electret material (e.g. teflon) to store charge for a long time and provide an initial charge for the charge self-excited system.

The stator comprises a second hard substrate 8, a first electrode 6, a second electrode 7 and a third insulating dielectric film 5, wherein the first electrode 6 and the second electrode 7 are electron pairs (with a gap therebetween, for example, 2mm) and are respectively positioned on the upper surface of the second hard substrate 8, and the upper surfaces of the first electrode 6 and the second electrode 7 are covered with the third insulating dielectric film 5.

In this embodiment, the second insulating dielectric film 4 and the third insulating dielectric film 5 can be made of dielectric films with poor charge retention capability (such as nylon), so as to avoid the accumulation of charges on the films to form high potential, thereby generating electrostatic shielding. The size of the second insulating dielectric film 4 should be larger than the size of the metal induction electrode 3, and the size of the third insulating dielectric film 5 should be larger than the size of the electron pair formed by the first electrode 6 and the second electrode 7 to prevent edge air breakdown.

The output end of the first electrode 6 is connected to a first input end of a charge self-excitation system 9, the output end of the second electrode 7 is connected to a second input end of the charge self-excitation system 9, and the output end of the charge self-excitation system 9 is connected to the input end of the metal induction electrode 3 of the mover. The first input end and the second input end are positioned on the same side, and the continuous increase of the charges is realized by designing a connection mode of two input units in the charge self-excitation system 9 on the same side.

As shown in fig. 2, the charge self-excitation system 9 includes a self-voltage-doubling rectifying circuit and a rectifying diode connected in series:

the first input end is connected with one end of a first capacitor C1, the second input end is respectively connected with the anode of a first diode D1 and one end of a fourth capacitor C4, the cathode of the first diode D1 and the other end of the first capacitor C1 are connected in parallel and then respectively connected with the anode of a second diode D2 and one end of a second capacitor C2, the cathode of the second diode D2 and the other end of the fourth capacitor C4 are connected in parallel and then respectively connected with the anode of a third diode and one end of a fifth capacitor C5, the cathode of the third diode and the other end of the second capacitor are connected in parallel and then respectively connected with the anode of the fourth diode D4 and one end of a third capacitor C3, the cathode of the fourth diode D4 and the other end of the fifth capacitor C5 are connected in parallel and then connected with the anode of a fifth diode D5, the cathode of the fifth diode D5 and the other end of the third capacitor C3 are connected in parallel and then connected with the anode of a rectifier diode D6, and the cathode of the rectifier diode D6 are connected with the output end of the rectifier diode D6. The rectifier diode D6 has a unidirectional conduction function, and can ensure that only charges of one polarity are continuously injected into the metal induction electrode 3, thereby achieving the effect of charge accumulation. The model number of D1-D5 is 1N 4007; the model of the rectifier diode D6 is 2CL20 KV; the capacitance of C1, C2, C3, C4 and C5 is 2.2nF, but the capacitance can be changed, and the smaller the capacitance value, the faster the excitation speed.

In this embodiment, the self-voltage-doubling rectifying circuit can select different numbers of units as required to achieve a faster charge increase (excitation) speed. Excitation voltage V of self-voltage-doubling rectifying circuit_EThe relationship with the surface charge of the metal induction electrode 3 of the mover is as follows:

d1 is the distance, ε, between the second and third insulating dielectric films₀Is the vacuum dielectric constant; s is the area of the metal sensing electrode 3. As can be seen from the equation, the electric charge on the metal inductive electrode 3 of the mover is proportional to the excitation voltage of the self-voltage-multiplying rectifier circuit, and it is described that the electric charge on the metal inductive electrode 3 of the mover increases as the excitation voltage increases.

In this embodiment, the metal sensing electrode 3, the first electrode 6, and the second electrode 7 may be metal electrodes, or may be other non-metal conductive materials such as conductive silica gel, ITO, and the like.

In this embodiment, an air gap (i.e., a distance between the second insulating dielectric film and the third insulating dielectric film, the distance being d1) exists between the stator and the mover, so as to form a suspension-type sliding structure, and generate electric energy by using an electrostatic induction effect.

In this embodiment, the operation of the charge self-excitation system 9 during the periodical slipping process is shown in fig. 3.

In the initial state (fig. 3a), the first insulating dielectric film 2 injects less charge (for example, negative charge) in advance, and the voltage across the self-voltage-doubling rectifying circuit (VMC) is zero. When the mover starts to operate periodically, the potential difference between the stator electrodes causes an alternating current output (fig. 3b, fig. 3c), both ends of the VMC start to charge (e.g., increase to Vo), the output voltage increases with the increase of the operation time (e.g., increase to 3Vo), and the electric charge (positive charge) output from the excitation system 9 to the metal induction electrodes 3 of the mover is accumulated continuously. The polarity of the charge initially injected by the first insulating dielectric film 2 on the rotor is opposite to that of the charge on the metal induction electrode 3, and the charge and the metal induction electrode can just act synergistically to induce the movement of electrons in the stator electrode, so that the induction output of the suspended sliding TENG is continuously increased. After several cycles, the voltage at the two ends of the VMC tends to be stable, the charge output to the metal induction electrode 3 of the mover tends to be in a saturated state, and the output reaches a maximum value (for example, increased to 5Vo), thereby implementing a charge self-excitation operation mode, as shown in fig. 3 d.

Fig. 4 is a comparison of the dynamic output charge density curves for four operating conditions. FIG. 4-is the traditional non-contact TENG output charge density curve, FIG. 4-is the output charge density curve of the TENG stator output connected to the self-voltage-doubling rectifying circuit but without the rectifying diode D6, at this time, positive and negative electrons will be injected into the metal induction electrode 3 at the same time, and the self-voltage-doubling rectifying circuit will consume part of the energy, resulting in output drop; fig. 4-c is the output charge density curve of the present invention, under the action of the rectifier diode D6, the surface charge density of the metal induction electrode 3 rapidly rises to a stable value; fig. 4-4 are graphs showing the rapid drop of the curve to the initial value when the charge self-energizing system 9 of the present invention is turned off. Therefore, the suspension sliding type charge self-excitation generator designed by the invention has strong electric output capability.

The induced charge in TENG will increase exponentially by virtue of the automatic switching of the series-parallel state of the capacitor bank in the charge self-energising system 9 during the slip process. For floating TENG, air breakdown occurs between the mover and the stator due to the presence of the air gap, so that a maximum charge density (Q) exists on the surface of the metal sensing electrode 3_Max) And satisfies the following conditions:

p is the pressure of the gas; d2 is the distance between the second electrode on the stator and the metal inductive electrode on the mover₀Is the vacuum dielectric constant; s is the area of the metal sensing electrode 3; a and B are constants determined by the composition and pressure of the gas, and A is 2.87X 105V (atm. m) at a standard atmospheric pressure of 101kPa^-1And B is 12.6. It is clear that the maximum charge density of floating TENG decreases with increasing air gap.

In the embodiment, the stator and the rotor can be arranged radially, linearly or curvilinearly around the circumference to form a suspension type charge self-excitation friction generator capable of collecting rotation or sliding energy; a friction generator that collects rotational energy is shown in fig. 5.

The base plates 15 of the rotor and the stator can adopt acrylic plates with the inner diameter, the outer diameter and the thickness of 19mm, 210mm and 4mm respectively, and the central circular hole is used for installing and connecting the rotating shaft. The fan-shaped electrode pairs 16 and 17 on the stator are both aluminum electrodes, the inner diameter, the outer diameter and the radial angle of the electrode 16 are respectively 72mm, 200mm and 30 degrees, the inner diameter, the outer diameter and the radial angle of the electrode 17 are respectively 70mm, 198mm and 30 degrees, and the gap between the

electrodes

16 and 17 is 2 mm; the third dielectric film 5 is entirely covered on the surface of the electrode pair with a nylon film 30 μm thick. On the rotor, the inner diameter, the outer diameter and the radial angle of the electrode 18 are respectively 70mm, 198mm and 30 degrees, and the thickness is 20 microns; a third dielectric film 5 is covered on the electrode 18; each independent insulating dielectric film 19 is a Polytetrafluoroethylene (PTFE) film with a thickness of 50 microns, and the inner diameter, the outer diameter and the radial angle of each insulating dielectric film 19 are 72mm, 200mm and 30 degrees respectively. The stator and the rotor are connected through a rotating shaft, and an extra electric brush is used for connecting an excitation path, so that the winding problem is avoided.

In order to test the output performance of the generator, the generator is driven by a stepping motor in different rotating speed modes, and the output performance of the generator is measured by a Gicherley electrometer (Keithley 6514) and a high-speed electrostatic voltmeter (Trek model 370).

As shown in fig. 6: by means of charge self-excitation, the induction output charge of the suspension slip type friction nano generator can reach 1 μ C at the driving frequency of 300rpm, the effective charge density reaches 71.5 μ C M-2 (fig. 6a), fig. 6b and fig. 6C are corresponding output current and output voltage curves, and can reach 76 μ A and 470V respectively, and it needs to be explained here that the voltage is measured under the external 10M Ω load because the self-excitation process requires the existence of current in the loop. Fig. 6d shows the output charge as a function of increasing rotational speed, and it can be seen that the transferred charge shows a tendency to increase and then decrease, since the charge excitation does not reach saturation for a short time at lower rotational speeds, and when the rotational speed increases, the centrifugal force and vertical vibration of the rotor increase accordingly due to imperfections in the manufacturing process, resulting in an increase in the gap between the rotor and the stator, and thus the maximum output charge decreases with increasing speed. In addition, the power of the generator at 300rpm with different external load resistance is shown in fig. 6e, and the peak power at 30M Ω is 34.68 mW. FIG. 6F shows the charging capability for different capacitors, for example, a 100 μ F capacitor can be charged to 50V at 180s, a 220 μ F capacitor can be charged to 30V at 300s, a 470 μ F capacitor can be charged to 15V at 300s, and a 1mF capacitor can be charged to 5V at 300 s.

As shown in FIG. 7, the generator of the present invention can be driven at a low wind speed of 3m/s, and thus can be used to collect breeze energy. FIG. 7a shows the charge output of the generator driven by different wind speeds, and the transferred charge amount is kept around 420 nC; this is different from the trend of motor drives, mainly because the corresponding rotational speeds are still relatively low even at high wind speeds. In addition, the uneven force and large fluctuation of wind force easily cause large vertical vibration, and transfer charge at low speed is reduced. Therefore, when driven by wind, the output charge of the floating-slip type self-excited friction nano-generator shows a constant trend due to the deviation of the two factors. FIG. 7b the generator achieves 16.7mW peak power at 7M/s wind speed at 120M Ω drag.

In the embodiment, 912 series-connected green LED lamps with the diameter of 5mm are respectively lightened by the suspension sliding type charge self-excitation friction generator under the driving force of the wind speed of 5m/s, and brighter light is emitted.

It will be understood by those of ordinary skill in the art that the foregoing embodiments are specific examples for carrying out the invention, and that various changes in form and details may be made therein without departing from the spirit and scope of the invention in practice.

Claims

1. A friction nano-generator based on suspension slip type charge self-excitation is characterized by comprising a TENG and a charge self-excitation system, wherein the charge self-excitation system is used for generating an excitation voltage so as to accumulate TENG charges; the TENG comprises a stator and a rotor, and an air gap exists between the stator and the rotor; the output end of the stator is connected with the input end of the charge self-excitation system, and the output end of the charge self-excitation system is connected with the input end of the rotor.

2. The friction nano-generator based on suspension sliding type charge self-excitation according to claim 1, wherein the mover comprises a first hard substrate (1), a first insulating dielectric film (2) and a metal induction electrode (3), the first insulating dielectric film (2) and the metal induction electrode (3) are respectively disposed on the lower surface of the first hard substrate (1) with a gap between the first insulating dielectric film (2) and the metal induction electrode (3), and the lower surface of the metal induction electrode (3) is further covered with a second insulating dielectric film (4).

3. The suspended sliding type charge self-excited friction nanogenerator according to claim 2, wherein the first dielectric film (2) is made of electret material, and the second dielectric film (4) is made of nylon film.

4. A friction nanogenerator based on suspended sliding charge self-excitation according to claim 2, wherein the size of the second insulating dielectric film (4) is larger than the size of the metal induction electrode (3).

5. The friction nanogenerator based on suspension sliding type charge self-excitation according to claim 1, wherein the stator comprises a second rigid substrate (8), a first electrode (6), a second electrode (7) and a third insulating dielectric film (5), the first electrode (6) and the second electrode (7) are respectively arranged on the upper surface of the second rigid substrate (8), and the upper surfaces of the first electrode (6) and the second electrode (7) are covered with the third insulating dielectric film (5).

6. A friction nano-generator based on suspension sliding type charge self-excitation according to claim 5, characterized in that the third insulating dielectric film (5) is nylon film.

7. The friction nanogenerator based on suspension slip type charge self-excitation according to claim 1, wherein the charge self-excitation system comprises a self-voltage-multiplying rectification circuit and a high-voltage-resistant rectification diode which are connected in series, and the specific circuit of the self-voltage-multiplying rectification circuit is as follows:

8. The levitation-slip based charge self-excitation friction nanogenerator according to claim 1, wherein the excitation voltage generated by the charge self-excitation system is related to TENG charge accumulation Q as follows:

9. The suspended-slip charge self-excitation based friction nanogenerator of claim 1, wherein TENG charge accumulation maximum charge density Q_MaxSatisfies the following conditions:

10. The levitation-slip-based charge self-excitation friction nanogenerator as claimed in claim 1, wherein the arrangement between the stator and the mover comprises a circumferential radial arrangement, a linear arrangement or a curvilinear arrangement, forming a friction nanogenerator that can collect rotational or sliding energy.