Rotary triboelectric nanogenerator based on automatic mode switching and charge excitation

Abstract

The present invention discloses a rotating friction nanogenerator based on automatic mode switching and charge excitation, including a main TENG with a centrifugal force driving layer and an excitation TENG with a gear set. Through the automatic mode conversion of the first stator and the first rotor on the main TENG, it can be suitable for different operating frequencies, thereby improving the durability and extending the service life of the TENG; at the same time, through the coordinated work of the excitation TENG, the electrical performance output of the friction nanogenerator is improved, and it can be directly used to collect rotational mechanical energy. The number of electrode pairs and the size can be adjusted and designed according to different scenarios, and the applicable scenarios are wide.

Description

Technical Field

[0001] The invention relates to the technical field of generators, and in particular to a rotary friction nanogenerator based on automatic mode switching and charge excitation. Background Art

[0002] With the rapid development of big data and the Internet of Things, various types of sensors are emerging and applied in various distributed fields. Although most of these widely distributed sensors do not require high-power drive, it is difficult to maintain manual maintenance if all sensors are powered only by batteries, and the extensive use of batteries will cause certain environmental pollution. The friction nanogenerator based on the coupling of triboelectricity and electrostatic induction has been proven to be an effective way to use environmental mechanical energy to realize self-powered and distributed sensor devices. This friction nanogenerator (TENG) has the advantages of low production cost, light weight, rich structure and material selection, etc., and has broad application prospects and extensive research interests.

[0003] In the practical application of TENG to obtain mechanical energy from the surrounding environment, the electrical output performance of TENG is an important issue we are concerned about. Its surface charge density is the most important parameter that determines the output performance of TENG. In addition, the heat generated by sliding friction in the medium and high frequency regions and the huge wear on the material surface seriously reduce the electrical output performance of TENG.

[0004] At present, many methods have been proposed to effectively improve the surface charge density, such as material surface modification, working condition control, ion implantation and charge excitation. However, for TENGs that work continuously for a long time, especially rotating and sliding TENGs, they will be subjected to strong mechanical wear in the medium or high frequency region, and their electrical output performance will be greatly reduced. Therefore, reasonable structural design is very necessary to effectively improve the durability of TENG. In addition, appropriate material selection can also effectively reduce the mechanical wear of TENG. The above methods effectively ensure the long-term durability of TENG. However, improving the electrical output performance and durability at the same time is still a challenge in rotating and sliding TENGs. Therefore, it will be very meaningful to further explore the optimal design that improves durability and electrical output performance at the same time. Summary of the invention

[0005] In view of the problems of low durability and output power of friction nanogenerators in the prior art, the present invention proposes a rotating friction nanogenerator based on automatic mode switching and charge excitation, which improves the electrical output performance of TENG through charge excitation. At the same time, through the structural design of the gear set and the centrifugal force driving layer, the speed reduction and automatic contact-separation working mode are realized, which effectively reduces the sliding friction heat generation and wear problems of TENG in the medium and high frequency range, and improves the working durability of TENG.

[0006] In order to achieve the above object, the present invention provides the following technical solutions:

[0007] A rotary friction nanogenerator based on automatic mode switching and charge excitation includes a main TENG with a centrifugal force driving layer and an excitation TENG with a gear set. The main TENG is connected to the excitation TENG through a half-wave rectifier bridge.

[0008] Preferably, the main TENG includes a first stator, a first rotor and a centrifugal driving layer; the first stator includes a first substrate 1, a first electrode pair 3 and 4, and a first dielectric film 5, the first electrode pair 3 and 4 are arranged on the surface of the first substrate 1, and the first dielectric film 5 covers the surface of the first electrode pair 3 and 4; the first rotor includes a second energy storage electrode pair 7 and 8, a second dielectric film 6 covering the surface of the electrode 8, and a second acrylic substrate 9, and the second energy storage electrode pair 7 and 8 are arranged on the surface of the second acrylic substrate 9.

[0009] Preferably, a first flexible foam 2 is further arranged between the first substrate 1 and the first electrode pair 3 and 4 .

[0010] Preferably, the centrifugal force driving layer includes four separation components and a third acrylic substrate 12, and the four separation components are evenly fixed on the third acrylic substrate 12, and the separation components are used to adjust the spacing distance between the first stator and the first rotor in the main TENG.

[0011] Preferably, the separation component includes a spring 10, a hollow steel ball 11, a fixed plate and a right-angled triangle skateboard, the fixed plate is fixed to the edge of the third acrylic substrate 12, one end of the spring 10 is connected to the fixed plate, the other end of the spring 10 is connected to the hollow steel ball 11, and the hollow steel ball 11 is horizontally placed on the third acrylic substrate 12; the first straight side of the right-angled triangle skateboard is fixed to the surface edge of the second acrylic substrate 9, the second straight side of the right-angled triangle skateboard and the second acrylic substrate 9 are perpendicular to each other and away from the edge of the second acrylic substrate 9, and the hollow steel ball 11 slides on the hypotenuse of the right-angled triangle skateboard.

[0012] Preferably, the excitation TENG includes a second stator and a second rotor; the second rotor includes a third acrylic substrate 14, a second flexible foam 15 covering the lower surface of the third acrylic substrate 14 of the second rotor, and a third dielectric film covering the lower surface of the second flexible foam 15; the second stator includes a third electrode pair 18 and 19, and a fourth dielectric film 17 covering the upper surface of the third electrode pair 18 and 19, and the third electrode pair covers the third electrode pair 18 and 19 and is arranged on the upper surface of the fourth acrylic substrate 20.

[0013] Preferably, the excitation TENG further includes a gear set, which includes a central rotating shaft 25, a driving wheel 22, a first driven wheel 23, a second driven wheel 24 and a third driven wheel 21, and the central rotating shaft 25 is a common rotating shaft of the main TENG and the excitation TENG;

[0014] The driving wheel 22 is on the central rotating shaft 25 and rotates in the same direction, the first driven wheel 23 is engaged with the driving wheel 22, the second driven wheel 24 is bonded to the upper surface of the first driven wheel 23, the third driven wheel 21 is engaged with the second driven wheel 24, the third driven wheel 21 is sleeved on the central rotating shaft 25 and the upper surface of the third driven wheel 21 is fixed to the lower surface of the third acrylic substrate 14 of the second rotor.

[0015] Preferably, the third electrode pair 18 and 19 are respectively connected to the input end of the half-wave rectifier bridge, the output negative electrode of the half-wave rectifier bridge is connected to the electrode 7, and the output positive electrode is connected to the electrode 8.

[0016] Preferably, the rotation speed of the excitation TENG is N times the rotation speed of the main TENG, and N<1.

[0017] Preferably, the friction nanogenerator is used in water flow driving and forest environment fire monitoring.

[0018] In summary, due to the adoption of the above technical solution, compared with the prior art, the present invention has at least the following beneficial effects:

[0019] The friction nanogenerator of the present invention comprises a main TENG having a centrifugal force driving layer and an excitation TENG having a gear set. Through the automatic mode conversion of the first stator and the first rotor on the main TENG, it can be applied to different operating frequencies, thereby improving durability and extending the service life of the TENG.

[0020] At the same time, by stimulating the collaborative work of TENG, the electrical performance output of the friction nanogenerator is improved, which can be directly used to collect rotational mechanical energy. The number of electrode pairs and size can be adjusted according to different scenarios, and it has a wide range of applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of a rotary friction nanogenerator based on automatic mode switching and charge excitation according to an exemplary embodiment of the present invention.

[0022] Figure 2 a is a simplified schematic diagram of a gear set according to an exemplary embodiment of the present invention; Figure 2 b is a schematic diagram of a gear set according to an exemplary embodiment of the present invention.

[0023] Figure 3 a is a schematic diagram showing the relationship between the output charge and the rotation speed of the main TENG according to an exemplary embodiment of the present invention; Figure 3 b is a schematic diagram showing the relationship between the output voltage and the rotation speed of the main TENG according to an exemplary embodiment of the present invention; Figure 3 c is a schematic diagram showing the relationship between the short-circuit current and the rotation speed of the main TENG according to an exemplary embodiment of the present invention.

[0024] Figure 4 Schematic diagram of the relationship between the output charge, voltage and rotation speed of the excitation TENG according to an exemplary embodiment of the present invention.

[0025] Figure 5 a is a schematic diagram of the output voltage of the excitation TENG and the main TENG in the unexcited and excited states according to an exemplary embodiment of the present invention; Figure 5 b is a schematic diagram of the output power of the excitation TENG and the main TENG under unexcitation and excitation conditions according to an exemplary embodiment of the present invention.

[0026] Figure 6 Schematic diagram of charging curves of a generator for different capacitors according to an exemplary embodiment of the present invention.

[0027] Figure 7 FIG. 1 is a schematic diagram of a generator driving an LED lamp according to an exemplary embodiment of the present invention. DETAILED DESCRIPTION

[0028] The present invention is further described in detail below in conjunction with the examples and specific implementation methods. However, this should not be understood as the scope of the above subject matter of the present invention being limited to the following examples, and all technologies realized based on the content of the present invention belong to the scope of the present invention.

[0029] In the description of the present invention, it is necessary to understand that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0030] like Figure 1 As shown, the present invention provides a rotary friction nanogenerator based on automatic mode switching and charge excitation, including a main TENG with a centrifugal force driving layer and an excitation TENG with a gear set, and the main TENG is connected to the excitation TENG through a half-wave rectifier bridge 13.

[0031] In this embodiment, the main TENG with a centrifugal force driving layer includes a first stator, a first rotor and a centrifugal force driving layer. The first stator includes a first acrylic substrate 1, a first flexible foam 2 (which reduces wear and improves contact efficiency), a first electrode pair 3 and 4, and a first dielectric film 5 covering the lower surface of the first electrode pair. The first electrode pair 3 and 4 are arranged on the lower surface of the flexible foam 2. The first rotor includes a second energy storage electrode pair 7 and 8, a second dielectric film 6 covering the electrode 8, and a second acrylic substrate 9. The second energy storage electrode pair 7 and 8 are arranged on the upper surface of the second acrylic substrate 9. The centrifugal driving layer includes four separation components and a third acrylic substrate 12, and the four separation components are evenly fixed on the third acrylic substrate 12; the separation components include a spring 10, a hollow steel ball 11, a fixed plate and a right-angled triangle slide plate (acrylic material can be used), the fixed plate (the fixed plate is an acrylic plate with dimensions of 9 mm wide, 16 mm high and 2 mm thick) is fixed on the edge of the third acrylic substrate 12 (for example, 10 mm away from the edge), one end of the spring 10 is connected to the fixed plate, and the other end of the spring 10 is connected to the hollow steel ball 11, and the hollow steel ball 11 is horizontally placed on the third acrylic substrate 12, the first straight side (the longer side) of the right-angled triangle slide plate is fixed to the lower surface edge of the second acrylic substrate 9, the second straight side (the shorter side) of the right-angled triangle slide plate and the second acrylic substrate 9 are perpendicular to each other but away from the edge of the third acrylic substrate 12, and the hollow steel ball 11 slides on the hypotenuse of the right-angled triangle slide plate.

[0032] In this embodiment, the excitation TENG with a gear set includes a second stator, a second rotor and a gear set. The second rotor includes a third acrylic substrate 14 (the third acrylic substrate 14 of the second rotor is evenly divided into 8 sector-shaped parts), a second flexible foam 15 covering the lower surface of the third acrylic substrate 14 of the second rotor (the number of the second flexible foam 15 is 4, which are attached to the sector-shaped parts of the third acrylic substrate 14 of the second rotor at intervals, and act as a slider in friction electrification, which plays a role in reducing wear and improving contact efficiency. In friction electrification, the second stator is generally stationary and the second rotor slides on the second stator), and a third dielectric film covering the lower surface of the second flexible foam 15; the second stator includes a third electrode pair 18 and 19, a fourth dielectric film 17 covering the third electrode pair, and a fourth acrylic substrate 20, and the third electrode pair 18 and 19 are arranged on the upper surface of the fourth acrylic substrate 20;

[0033] like Figure 2As shown, the gear set includes a driving wheel 22, a first driven wheel 23, a second driven wheel 24 and a third driven wheel 21. The driving wheel 22 is fixed on the central rotating shaft 25 by screws and rotates in the same direction. The first driven wheel 23 is engaged on the right side of the driving wheel 22. The radius of the first driven wheel 23 is 25, and the radius of the driving wheel 22 is 8. Then they overlap by 1mm when engaged, so the center of the first driven wheel 23 is 32mm away from the center of the driving wheel 22; the first driven wheel 23 and the second driven wheel 24 are glued, and the second driven wheel 24 is attached to the lower surface of the fourth acrylic substrate 20; the third driven wheel 21 is attached to the lower surface of the third acrylic substrate 14 of the second rotor, and is engaged with the second driven wheel 24 through gears. The driving wheel 22, the first driven wheel 23, the second driven wheel 24 and the third driven wheel 21 are all hollow structures. Both the main TENG and the excitation TENG use the same central rotating shaft 25, but the second stator in the excitation TENG is not connected to the central rotating shaft 25, and the central rotating shaft 25 passes through the middle hole of the second stator.

[0034] In this embodiment, the driving wheel 22 with 16 teeth is tightly fixed on the central rotating shaft 25 of the main TENG and the excitation TENG. The driving wheel 22 drives the first driven wheel 23 (the number of teeth of the first driven wheel 23 is 48 teeth) to rotate at the same linear speed through gear meshing, the first driven wheel 23 and the second driven wheel 24 are tightly fixed together and rotate at the same angular velocity, and the second driven wheel 24 drives the third driven wheel 21 (the number of teeth of the third driven wheel 21 is 48 teeth) to rotate at the same linear speed through gear meshing, thereby driving the third acrylic substrate 14 of the second rotor to rotate, that is, the second rotor rotates. The third driven wheel 21 is sleeved on the central rotating shaft 25 of the excitation TENG, so it can rotate freely on the central rotating shaft 25.

[0035] In this embodiment, the number of electrode pairs on the first stator and the first rotor in the main TENG can be changed. Similarly, the number of electrode pairs on the second stator and the second rotor in the excitation TENG can also be changed. The number of electrode pairs can be set as needed.

[0036] In this embodiment, the second energy storage electrode pair 7 and 8 on the rotor in the main TENG is connected to the third electrode pair 18 and 19 on the second stator in the excitation TENG through a half-wave rectifier bridge 13.

[0037] In this embodiment, the excitation TENG reduces the rotation speed of the second rotor of the excitation TENG to N times (N < 1, for example, N is 1 / 9) the rotation speed of the first rotor in the main TENG through the gear set speed change, ensuring that the second rotor always operates at a lower frequency. The AC signal output by the excitation TENG is converted into a DC signal through a half-wave rectifier bridge 13 and output to the second energy storage electrode pair 7 and 8 of the main TENG to improve the electrical output performance of the main TENG.

[0038] For example, the third acrylic substrate 14 and the third driven wheel 21 in the second rotor of the excitation TENG are tightly fixed and can rotate together around the central rotating axis 25; the driving wheel 22 has 16 teeth, the first driven wheel 23 has 48 teeth, the second driven wheel 24 has 16 teeth, and the third driven wheel 21 has 48 teeth. Therefore, after two speed changes, the rotation speed of the second rotor of the excitation TENG can be changed to 1 / 9 of the rotation speed of the first rotor of the main TENG.

[0039] In this embodiment, the third electrode pair 18 and 19 on the second stator in the excitation TENG are respectively connected to the input end of the half-wave rectifier bridge 13, and the output end of the half-wave rectifier bridge 13 is connected to the second energy storage electrode pair 7 and 8 on the rotor (the output negative electrode is connected to electrode 7, and the output positive electrode is connected to electrode 8).

[0040] In this embodiment, when the main TENG rotates at a low speed, due to the low working frequency (for example, less than 2Hz), the centrifugal force of the centrifugal driving layer is less than the elastic force of the spring 10, and the hollow steel ball 11 approaches the second straight side along the hypotenuse of the right triangle slide, thereby pushing the first rotor to move upward, and the first stator and the first rotor of the main TENG are in close contact. At this time, the working principle of the main TENG is the coupling of friction electrification and electrostatic induction; when the main TENG works at a high frequency (for example, greater than or equal to 2Hz), since the centrifugal force of the centrifugal driving layer is greater than the elastic force of the spring 10, the spring contracts, that is, the four small balls 11 spread to the surroundings respectively, and the first rotor of the main TENG moves downward, then the first stator and the first rotor are separated, and at this time, the working principle of the main TENG is electrostatic induction. When the main TENG works periodically, the charges bound to the surface of the second dielectric film 6 in the first rotor and the second energy storage electrode pair 7, 8 will drive the electrons on the first stator to periodically transfer back and forth between the first electrode pair 3 and 3, thereby outputting an AC signal to the outside.

[0041] Therefore, the first stator and the first rotor of the main TENG can realize automatic conversion of the contact-separation mode at low frequency and high frequency, respectively, effectively avoiding contact wear during high-frequency operation and maximizing the service life of the device.

[0042] During the rotation of the main TENG, due to the interaction between the centrifugal force and the elastic force of the spring 10 in the centrifugal force driving layer, the descending distance of the first rotor in the main TENG gradually increases with the increase of the rotation speed, that is, the higher the rotation speed, the more the first rotor in the main TENG descends, and the longer the interval between the first rotor and the first stator. When the main TENG is in a stationary state, the spring 10 is in a normal state (generally a deformation of 2mm occurs. In order to make the ball more stable, the initial deformation of the spring is 2mm, so at low frequencies, the centrifugal force is less than the spring elastic force, and the ball still does not slide), the first stator and the first rotor are in close contact and fit. When the main TENG is in a working state, as the rotation speed increases, the first stator and the first rotor of the main TENG gradually change from the initial close contact state to a separation state.

[0043] like Figure 3 As shown in Figure 2, the transferred charge output of the main TENG gradually decreases with the increase of the rotation speed. The charge outputs at rotation speeds of 60rpm, 120rpm, 180rpm, 240rpm, 300rpm, 360rpm, and 420rpm are 680nC, 600nC, 500nC, 480nC, 4000nC, 380nC, and 300nC, respectively.

[0044] like Figure 4 As shown in the figure, the charge (Charge) and voltage (Voltage) output of the excitation TENG are basically not affected by the change of the rotation speed, that is, whether it is rotating at high or low frequency, the excitation TENG can continuously inject charge into the main TENG, significantly improving the electrical performance output of the main TENG. For example, when the rotation speed is 7rpm, 13rpm, 20rpm, 27rpm, 33rpm, 40rpm, and 47rpm, the charge output of the excitation TENG is about 500nC, and the voltage output is about 3.5KV.

[0045] Therefore, the friction nanogenerator of the present invention can realize automatic switching of the contact-separation working mode at different working frequencies, and can quickly generate an electrical performance output greater than that of the ordinary contact-slip TENG under the charge excitation of the excitation TENG, and has an output durability far higher than that of the ordinary contact-slip TENG.

[0046] In this embodiment, the half-wave rectifier bridge 13 ensures that the charge for exciting the TENG can be continuously injected into the second energy storage electrode pair 7 and 8 of the main TENG, thereby enhancing the electrostatic induction of the main TENG and achieving the effect of improving the electrical output performance of the main TENG.

[0047] like Figure 5As shown in a, the output voltages of the excitation TENG (E-TENG) and the main TENG in the unexcited (M-TENG) and excited (CEMA-TENG) cases are 1KV, 1.1KV, and 1.6KV, respectively; Figure 5 As shown in Figure b, the output power of the excitation TENG (E-TENG), the main TENG in the unexcitation (M-TENG) and the excitation (CEMA-TENG) cases are 2.5mW, 6mW and 19mW respectively. It can be seen that the maximum output power of CEMA-TENG is about twice the sum of M-TENG and E-TENG, which shows that the friction nanogenerator of the present invention has high electrical performance output.

[0048] In this embodiment, the inner diameter, outer diameter and thickness of the first acrylic substrate 1 of the first stator in the main TENG are 16 mm, 128 mm and 4 mm respectively. The lower surface of the first acrylic substrate 1 is covered with a first flexible foam 2 for alleviating the friction loss of the material. The inner diameter, outer diameter and thickness are 12 mm, 128 mm and 2 mm respectively. The inner diameter and outer diameter of the first electrode pair 3 and 4 are 24 mm, 104 mm and 27 mm, 114 mm respectively. The surface of the first electrode pair 3 and 4 is covered with a first dielectric film 5.

[0049] The inner diameter, outer diameter and thickness of the second acrylic substrate 9 in the first rotor are 16 mm, 123 mm and 4 mm respectively. The sizes of the second electrode pairs 7 and 8 are the same as those of the first electrode pairs 3 and 4, that is, the inner diameter and outer diameter are 24 mm, 104 mm and 27 mm, 114 mm respectively. The surface of the electrode 7 is covered with a second dielectric film 6 with an inner diameter, outer diameter and thickness of 24 mm, 104 mm and 50 um respectively.

[0050] The four separation components of the centrifugal drive layer are fixed on the third acrylic substrate 12, and the inner diameter, outer diameter and thickness of the third acrylic substrate 12 are 16mm, 128mm and 4mm respectively. The outer diameter of the hollow steel ball 11 is 13mm, and the length of the spring 10 is 20mm. The second energy storage electrode pair 7 and 8 of the excitation TENG and the main TENG are connected by using brushes and a half-wave rectifier bridge 13 to avoid circuit winding problems.

[0051] In this embodiment, the inner diameter, outer diameter, and thickness of the fourth acrylic substrate 20 of the second stator in the excitation TENG are 54 mm, 120 mm, and 4 mm, respectively; the inner diameter, outer diameter, and thickness of the third acrylic substrate 14 of the second rotor are 16 mm, 120 mm, and 4 mm, respectively. The third acrylic substrate 14 and the fourth acrylic substrate 20 of the second rotor are both circular and have a circular hole in the center for mounting and connecting the rotating shaft. The lower surface of the third acrylic substrate 14 in the second rotor is pasted with a second flexible foam 15 to alleviate the friction loss between the devices. The inner diameter, outer diameter, and thickness are 58 mm, 116 mm, and 2 mm, respectively. The lower surface of the second flexible foam 15 is also covered with a 50-micron-thick third dielectric film (a nylon film can be used). The third electrode pair 18 and 19 in the second stator are both aluminum electrodes. The inner diameter, outer diameter and radial angle of electrode 18 are 57 mm, 112 mm and 45° respectively; the inner diameter, outer diameter and radial angle of electrode 19 are 60 mm, 120 mm and 45° respectively; the gap between electrodes 18 and 19 is 2 mm; the upper surface of the third electrode pair is covered with a 50-micron thick fourth dielectric film 17 (FEP dielectric film).

[0052] In the gear set, the driving wheel 22 with 16 teeth is tightly fixed on the central rotating shaft 25 of the excitation TENG. The driving wheel 22 drives the first driven wheel 23 to rotate at the same linear speed. The number of teeth of the first driven wheel 23 is 48. The first driven wheel 23 and the second driven wheel 24 are tightly fixed together and rotate at the same angular velocity. The second driven wheel 24 drives the third driven wheel 21 to rotate at the same linear speed. The number of teeth of the third driven wheel 21 is 48. The third driven wheel 21 is sleeved on the central rotating shaft 25 of the excitation TENG and can rotate freely on the central rotating shaft 25.

[0053] In order to test the output performance of the generator of the present invention, during the electrical performance output test of TENG, a programmable stepper motor was used to simulate the mechanical energy of external rotation and drive TENG under different speed modes. The output end of TENG was connected to an electrometer (Keithley 6514) and a high-speed electrostatic voltmeter (Trek model 370) to display the output of its transferred charge, short-circuit current and open-circuit voltage.

[0054] like Figure 3 As shown in the figure: after the charge excitation of TENG, the electrical performance output of the triboelectric nanogenerator under different speed driving, its transfer charge and open circuit voltage show a trend of gradually decreasing with the increase of speed, and the output current gradually increases with the increase of speed. The maximum output charge and minimum output charge output of the main TENG reach 796nC and 384nC respectively ( Figure 3 a), the maximum voltage and minimum voltage are 3400V and 2300V respectively ( Figure 3b), the corresponding minimum short-circuit current and maximum short-circuit current are 10.5μA and 47μA respectively ( Figure 3 c).

[0055] In addition, if Figure 5 As shown in a, the output voltages of the excitation TENG (E-TENG) and the main TENG in the unexcited (M-TENG) and excited (CEMA-TENG) cases are 1KV, 1.1KV, and 1.6KV, respectively; Figure 5 As shown in Fig. 2a, the output power of the excited TENG (E-TENG) and the main TENG in the unexcited (M-TENG) and excited (CEMA-TENG) cases are 2.5 mW, 6 mW, and 19 mW, respectively. It can be seen that the maximum output power of CEMA-TENG is about twice the sum of M-TENG and E-TENG. The results show that charge excitation can significantly improve the electrical performance output of the main TENG.

[0056] like Figure 6 As shown, the generator of the present invention can charge different commercial capacitors driven by water flow, such as charging 470μF, 1mF and 3.3mF capacitors to 3.5V, 3.5V and 2.9V respectively. After charging, the capacitor can drive a commercial fire alarm module. When fire appears, the alarm module can send out a red light alarm, which can be used for forest environment monitoring. In addition, it can also drive two thermometers and hygrometers connected in series at the same time.

[0057] like Figure 7 As shown, the generator of the present invention can successfully light up 944 series-connected green LED lamps with a diameter of 5 mm when driven by a motor of 60 rpm, and can emit very bright light.

[0058] Due to the contact-separation automatic mode switching and charge excitation strategy of the friction nanogenerator of the present invention, the mechanical durability of TENG is improved, the operating frequency range is expanded, and its electrical performance output is improved at the same time. More importantly, the friction electric nanogenerator demonstrated in this study will provide a power source option for the Internet of Things in remote areas with rivers or streams.

[0059] Those skilled in the art will appreciate that the above-mentioned embodiments are specific examples for implementing the present invention, and in actual applications, various changes may be made thereto in form and detail without departing from the spirit and scope of the present invention.

Claims

1. Rotary triboelectric nanogenerator based on automatic mode switching and charge excitation, It is characterized in that It includes a main TENG with a centrifugal force driving layer and an excitation TENG with a gear set, and the main TENG is connected to the excitation TENG through a half-wave rectifier bridge; The centrifugal force driving layer comprises four separation components and a third acrylic substrate (12), the four separation components are respectively and evenly fixed on the third acrylic substrate (12), and the separation components are used to adjust the spacing distance between the first stator and the first rotor in the main TENG; The excitation TENG comprises a second stator and a second rotor; the second rotor comprises a third acrylic substrate (14), a second flexible foam (15) covering the lower surface of the third acrylic substrate (14) of the second rotor, and a third dielectric film covering the lower surface of the second flexible foam (15); the second stator comprises an electrode (18) of a third electrode pair and another electrode (19) of the third electrode pair, a fourth dielectric film (17) covering the upper surfaces of one electrode (18) of the third electrode pair and another electrode (19) of the third electrode pair, and one electrode (18) of the third electrode pair and another electrode (19) of the third electrode pair are arranged on the upper surface of the fourth acrylic substrate (20); The separation component comprises a spring (10), a hollow steel ball (11), a fixing plate and a right-angled triangle slide plate, wherein the fixing plate is fixed to the edge of the third acrylic substrate (12), one end of the spring (10) is connected to the fixing plate, the other end of the spring (10) is connected to the hollow steel ball (11), and the hollow steel ball (11) is horizontally placed on the third acrylic substrate (12); the first straight side of the right-angled triangle slide plate is fixed to the surface edge of the second acrylic substrate (9), the second straight side of the right-angled triangle slide plate and the second acrylic substrate (9) are perpendicular to each other and away from the edge of the second acrylic substrate (9), and the hollow steel ball (11) slides on the hypotenuse of the right-angled triangle slide plate; The excitation TENG further comprises a gear set, the gear set comprising a central rotating shaft (25), a driving wheel (22), a first driven wheel (23), a second driven wheel (24) and a third driven wheel (21), the central rotating shaft (25) being a common rotating shaft of the main TENG and the excitation TENG; The driving wheel (22) rotates in the same direction on the central rotating shaft (25), the first driven wheel (23) engages with the driving wheel (22), the second driven wheel (24) is bonded to the upper surface of the first driven wheel (23), the third driven wheel (21) engages with the second driven wheel (24), the third driven wheel (21) is sleeved on the central rotating shaft (25), and the upper surface of the third driven wheel (21) is fixed to the lower surface of the third acrylic substrate (14) of the second rotor; the second driven wheel (24) is in contact with the lower surface of the fourth acrylic substrate (20); the second stator for exciting the TENG is not connected to the central rotating shaft (25), that is, the central rotating shaft (25) passes through the middle hole of the second stator.

2. The rotary friction nanogenerator based on mode automatic switching and charge excitation as claimed in claim 1, It is characterized in that The main TENG comprises a first stator, a first rotor and a centrifugal force driving layer; the first stator comprises a first substrate (1), one electrode (3) of a first electrode pair and another electrode (4) of the first electrode pair, and a first dielectric film (5); one electrode (3) of the first electrode pair and another electrode (4) of the first electrode pair are arranged on the surface of the first substrate (1); the first dielectric film (5) covers the surfaces of one electrode (3) of the first electrode pair and another electrode (4) of the first electrode pair; the first rotor comprises one electrode (7) of a second energy storage electrode pair and another electrode (8) of the second energy storage electrode pair, a second dielectric film (6) covering the surface of the other electrode (8) of the second energy storage electrode pair, and a second acrylic substrate (9); one electrode (7) of the second energy storage electrode pair and another electrode (8) of the second energy storage electrode pair are arranged on the surface of the second acrylic substrate (9).

3. The rotary friction nanogenerator based on mode automatic switching and charge excitation as claimed in claim 2, It is characterized in that A first flexible foam (2) is also arranged between the first substrate (1), one electrode (3) of the first electrode pair and the other electrode (4) of the first electrode pair.

4. The rotary friction nanogenerator based on mode automatic switching and charge excitation as claimed in claim 1, It is characterized in that One electrode (18) of the third electrode pair and the other electrode (19) of the third electrode pair are respectively connected to the input end of the half-wave rectifier bridge, the output negative electrode of the half-wave rectifier bridge is connected to one electrode (7) of the second energy storage electrode pair, and the output positive electrode is connected to the other electrode (8) of the second energy storage electrode pair.

5. The rotary friction nanogenerator based on mode automatic switching and charge excitation as claimed in claim 1, It is characterized in that The rotation speed of the excitation TENG is N times the rotation speed of the main TENG, and N<1.

6. The rotary friction nanogenerator based on mode automatic switching and charge excitation as claimed in claim 1, It is characterized in that The friction nanogenerator is applied in water flow driving and forest environment fire monitoring.

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