A ball bearing type friction-electromagnetic composite energy harvesting system and a parameter optimization design method thereof

Abstract

This invention discloses a ball bearing-type triboelectric-electromagnetic composite energy harvesting system and its parameter optimization design method, including an inner ring stator, an outer ring rotor, a wind cup, an induction coil, a permanent magnet array, a triboelectric nano-power generation unit, and a rotor-side energy management unit. The wind cup drives the outer ring rotor to rotate, simultaneously realizing triboelectric nano-power generation and electromagnetic induction power generation. The two power sources are isolated, rectified, and regulated before being output through a slip ring. The optimization method optimizes the parameters of the rolling element diameter, electrode gap, and electrode center angle by establishing a multiphysics simulation model. This invention integrates the bearing and dual power generation unit, resulting in a compact structure and strong versatility. It solves the problems of difficult maintenance and poor stability of traditional self-powered systems, as well as the difficulty in miniaturizing existing harvesters and their poor power generation performance, making it suitable for the in-situ self-powering requirements of IoT sensors.

Description

Technical Field

[0001] This invention relates to the field of energy harvesting system technology, and in particular to a ball bearing type friction-electromagnetic composite energy harvesting system and its parameter optimization design method. Background Technology

[0002] Traditional battery-powered solutions suffer from limited lifespan and the need for frequent replacement and maintenance, especially in inaccessible locations such as remote mountainous areas, high-altitude equipment, or enclosed machinery, where maintenance costs are extremely high and environmental pollution risks exist. Meanwhile, single-source energy harvesting technologies like solar power are significantly limited by weather, sunlight conditions, and installation location, resulting in insufficient power supply stability.

[0003] TENG can effectively collect low-frequency vibration energy and wind energy from the environment and has high voltage output characteristics; EMG has the advantage of high current output under large amplitude and high speed. Combining the two to achieve complementary advantages is an effective way to solve the problem of all-weather self-powering of IoT nodes.

[0004] However, existing hybrid generators are often complex in structure and bulky, making them difficult to integrate into miniaturized devices. Ball bearings, as ubiquitous standard components in various rotating machinery (such as motors, fans, conveyor belt rollers, and vehicle wheel hubs), possess immense potential for structural integration. If energy harvesting can be achieved using the ball bearing's own rotating structure, it could provide in-situ power to equipment condition monitoring sensors (such as vibration and temperature sensors), realizing a true "smart bearing" or self-powered node. However, when converting standard ball bearings into hybrid generators, the influence of component dimensions (such as rolling element diameter, micron-level electrode gap, and electrode coverage angle) on power generation performance exhibits a complex nonlinear relationship. Currently, the lack of generalized structural optimization design guided by accurate multiphysics simulations results in many bearing-based energy harvesters failing to achieve optimal output performance. Summary of the Invention

[0005] The technical problem to be solved by this invention is that traditional self-powered solutions are difficult to maintain and have poor power supply stability. Existing composite energy harvesters have complex structures and are difficult to miniaturize and integrate. Furthermore, bearing-type harvesters lack accurate simulation and optimization, resulting in the inability to achieve optimal power generation performance.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a ball bearing type triboelectric-electromagnetic composite energy harvesting system, including an annular inner ring stator and an outer ring rotor coaxially rotatably connected to the inner ring stator. An installation rod is radially fixedly connected to the outer side wall of the outer ring rotor. An induction coil is wound on the installation rod. A wind cup is fixed to the outer end of the installation rod. A permanent magnet array is installed inside the inner ring stator. A triboelectric nano-power generation unit is set at the gap between the inner ring stator and the outer ring rotor. A collector ring electrically connected to the induction coil and the triboelectric nano-power generation unit is installed on the outer side of the inner ring stator.

[0007] Preferably, the triboelectric nanogenerator unit includes a plurality of rolling elements that can be rolled between the inner stator and the outer rotor, and a comb-shaped copper electrode fixed to the inner sidewall of the outer rotor. The rolling elements are made of PTFE material.

[0008] Preferably, the comb-shaped copper electrode includes two sets of interlocking but non-contacting comb-shaped electrode plates, wherein the number of comb teeth in the two sets of comb-shaped electrode plates is equal to or an integer multiple of the number of rolling elements.

[0009] Preferably, the gap between the rolling element and the comb-shaped copper electrode along the radial direction of the outer ring rotor is no more than 0.1 mm, and welding fixing structures are provided between the two sides of the top of the rolling element and the inner wall of the outer ring rotor.

[0010] Preferably, a rotor-side energy management unit is installed on the outer side wall of the outer ring rotor. The comb-shaped copper electrode of the triboelectric nanogenerator and the output terminal of the induction coil are both electrically connected to the rotor-side energy management unit, and the rotor-side energy management unit is electrically connected to the collector ring.

[0011] Preferably, the rotor-side energy management unit includes an independent triboelectric rectifier bridge and an electromagnetic rectifier bridge. The triboelectric rectifier bridge is connected to the comb-shaped copper electrode, and the electromagnetic rectifier bridge is connected to the induction coil. Both the triboelectric rectifier bridge and the electromagnetic rectifier bridge are equipped with diodes for impedance isolation.

[0012] Preferably, the outer rotor and inner stator substrates are made of transparent acrylic or insulating resin material, and the comb-shaped copper electrodes are attached to or embedded in the inner wall of the outer rotor using flexible circuit technology.

[0013] Preferably, the permanent magnet array is arranged at uniform intervals along the circumference of the inner stator, and the magnetic field direction of the permanent magnet array is perpendicular to the axial direction of the induction coil.

[0014] A parameter optimization design method for a ball bearing-type friction-electromagnetic composite energy harvesting system includes the following steps: S1. Establish a multiphysics finite element simulation model that includes rolling elements, comb-shaped copper electrodes, inner stator and outer rotor structure, and use surface charge density as boundary condition to simulate the dynamic induction process of relative rotation between the PTFE rolling elements and the comb-shaped copper electrodes. S2. Using the diameter of the rolling element, the radial clearance between the rolling element and the comb-shaped copper electrode, and the central angle of the comb-shaped copper electrode as optimization variables, the influence of each variable on the system output potential and induced charge density is obtained through simulation. S3. Determine the optimal parameters based on the simulation results: the diameter of the rolling element is taken as the maximum allowable value of the bearing structure composed of the inner ring stator and the outer ring rotor; the radial clearance between the rolling element and the comb-shaped copper electrode is controlled within 0.1mm; and the central angle of the comb-shaped copper electrode is taken as the angle corresponding to the system output power balance point. S4. Connect the output terminal of the comb-shaped copper electrode of the triboelectric nanogenerator unit to the triboelectric rectifier bridge of the rotor-side energy management unit, and connect the output terminal of the induction coil to the electromagnetic rectifier bridge of the rotor-side energy management unit. Utilize the unidirectional conduction characteristic of the diode to achieve impedance isolation between the two power supplies. After rectification, the two power supplies are connected in parallel on the DC side and then the energy is stored by the energy storage capacitor and regulated by the low-dropout linear regulator. Finally, a stable DC voltage is output through the collector ring.

[0015] Preferably, in step S1, the multiphysics finite element simulation model needs to simulate the motion state of the outer rotor driving the rolling element to rotate around the inner stator, and simultaneously simulate the triboelectric charging process of the triboelectric nanogenerator and the electromagnetic induction process of the electromagnetic generator, so as to ensure that the simulation results are consistent with the actual working state.

[0016] This invention provides a ball bearing-type friction-electromagnetic composite energy harvesting system and its parameter optimization design method, which has the following beneficial effects.

[0017] 1. Adopting an integrated bearing composite structure, the triboelectric power generation unit and the electromagnetic power generation unit are integrated into the standard bearing structure. The structure is compact, small in size, and highly versatile. It can be directly adapted to various rotating machinery such as fans, motors, hubs, and rollers. It is easy to embed into miniaturized equipment and enclosed spaces, realize in-situ self-powering, and meet the all-weather power supply needs of IoT sensors.

[0018] 2. Triboelectric power generation and electromagnetic power generation complement each other. The triboelectric nano-power generation unit can efficiently collect low-frequency vibration energy and micro-wind energy, while the electromagnetic power generation unit outputs a large current under rotating conditions. The two work together and are not limited by light, weather or installation location. The power supply stability is significantly better than that of a single energy collection method.

[0019] 3. The use of comb-shaped copper electrodes in conjunction with rolling elements, with the gap between the rolling elements and electrodes precisely controlled within 0.1mm, combined with two sets of finger-inserted comb-shaped electrodes to achieve phase synchronization induction, resulting in high charge output efficiency and effectively improving triboelectric charging and charge collection capabilities. Attached Figure Description

[0020] The present invention will be further described below with reference to the accompanying drawings and embodiments: Figure 1 This is a schematic diagram of the structure of an embodiment of the present invention.

[0021] Figure 2 This is a schematic diagram of the internal structure of an embodiment of the present invention.

[0022] Figure 3 This is a structural front view of an embodiment of the present invention.

[0023] Figure 4 This is a schematic diagram of the comb-shaped copper electrode in an embodiment of the present invention.

[0024] Figure 5 This is a schematic diagram of the internal circuit topology and working principle of the rotor-side energy management unit in an embodiment of the present invention.

[0025] In the diagram: 1. Outer rotor; 2. Inner stator; 3. Wind cup; 4. Rolling element; 5. Comb-shaped copper electrode; 6. Permanent magnet; 7. Induction coil; 8. Rotor-side energy management unit. Detailed Implementation

[0026] like Figures 1 to 5 As shown, the present invention provides a ball bearing type triboelectric-electromagnetic composite energy harvesting system, including an annular inner stator 2 and an outer rotor 1 coaxially rotatably connected to the inner stator 2. A mounting rod is radially fixedly connected to the outer side wall of the outer rotor 1, an induction coil 7 is wound on the mounting rod, and a wind cup 3 is fixed to the outer end of the mounting rod. A permanent magnet array 6 is installed inside the inner stator 2. A triboelectric nanogenerator unit is provided at the gap between the inner stator 2 and the outer rotor 1. A collector ring electrically connected to the induction coil 7 and the triboelectric nanogenerator unit is installed on the outer side of the inner stator 2.

[0027] The outer ring rotor 1 and the inner ring stator 2 are modified versions of standard ball bearings. Both are annular structures and are coaxially assembled to ensure that the outer ring rotor 1 can rotate smoothly around the inner ring stator 2. This retains the mechanical support function of the ball bearings and provides an installation carrier for the triboelectric power generation unit and the electromagnetic power generation unit.

[0028] Under the action of wind, the wind cup 3 can drive the mounting rod to rotate, and the mounting rod drives the induction coil 7 to rotate. Since the permanent magnet array 6 is fixed in the inner ring stator 2, the induction coil 7 will cut the magnetic field lines during the rotation, thereby generating an induced current, which is then transmitted to the collector ring for transmission.

[0029] Similarly, during the rotation of the outer rotor 1, the outer rotor 1 drives the triboelectric nanogenerator unit to rotate and generate electricity through triboelectricity, and the generated electrical energy is also transmitted.

[0030] The slip ring, made of copper with excellent conductivity, is mounted on the outer side of the inner stator 2 and is electrically connected to the rotor-side energy management unit 8. Its core function is to solve the problem of energy extraction when the outer rotor 1 rotates. Since the outer rotor 1 is rotating, directly connecting it to an external load via wires would cause wire entanglement and wear, affecting the stability of power transmission. The slip ring is fixed to the inner stator 2, and the rotor-side energy management unit 8, which rotates synchronously with the outer rotor 1, contacts the slip ring through brushes, achieving entangle-free power transmission and ensuring that stable DC power after rectification and stabilization can be continuously delivered to the external load.

[0031] like Figure 2 As shown. The triboelectric nanogenerator unit includes several rolling elements 4 that are rotatably disposed between the inner stator 2 and the outer rotor 1, and a comb-shaped copper electrode 5 fixed to the inner sidewall of the outer rotor 1. The rolling elements 4 are made of PTFE material.

[0032] like Figure 2 and Figure 4 As shown. The comb-shaped copper electrode 5 includes two sets of interlocking but non-contacting comb-tooth electrode plates 51. The number of teeth in the two sets of comb-tooth electrode plates 51 is equal to or an integer multiple of the number of rolling elements 4.

[0033] As a preferred embodiment of the present invention, the gap between the rolling element 4 and the comb-shaped copper electrode 5 along the radial direction of the outer ring rotor 1 does not exceed 0.1 mm, and welding fixing structures are provided between the top two sides of the rolling element 4 and the inner wall of the outer ring rotor 1.

[0034] When the gap is too large, the induction effect between the rolling element 4 and the copper electrode weakens, and the output performance of triboelectric power generation drops sharply. When the gap is too small, the rolling element 4 comes into direct contact with the copper electrode, which leads to increased wear and shortens the service life. A gap of 0.05mm-0.1mm allows the system to operate in a quasi-contact mode, achieving high output performance close to contact friction while avoiding wear caused by direct contact, thus balancing power generation efficiency and equipment lifespan.

[0035] A rotor-side energy management unit 8 is installed on the outer wall of the outer rotor 1. The output terminals of the comb-shaped copper electrode 5 and the induction coil 7 of the triboelectric nanogenerator are both electrically connected to the rotor-side energy management unit 8. The rotor-side energy management unit 8 is electrically connected to the collector ring. The purpose of setting up the rotor-side energy management unit 8 is to solve the problem of easy short circuit when the high-voltage triboelectric generator and the low-resistance electromagnetic coil are directly connected in parallel, and to realize impedance isolation, rectification, current combining, and voltage stabilization of the two power sources, ultimately outputting stable DC power.

[0036] As a preferred embodiment of the present invention, the rotor-side energy management unit 8 includes an independent triboelectric rectifier bridge and an electromagnetic rectifier bridge. The triboelectric rectifier bridge is connected to the comb-shaped copper electrode 5, and the electromagnetic rectifier bridge is connected to the induction coil 7. Both the triboelectric rectifier bridge and the electromagnetic rectifier bridge are equipped with diodes for impedance isolation.

[0037] Triboelectric nanogenerators exhibit high voltage and high internal resistance characteristics, consisting of an AC voltage source connected in series with an internal capacitor. Electromagnetic generation, on the other hand, involves an AC voltage source connected in series with an inductor and internal resistance, exhibiting low voltage and low internal resistance characteristics. If the two are directly connected in parallel, the high-voltage charge generated by the triboelectric nanogenerators will instantly flow back into the low-impedance induction coil 7, causing a short circuit. The unidirectional conduction characteristic of a diode, however, enables complete isolation of the two power sources in terms of physical impedance, avoiding short circuits and ensuring stable transmission of each power source.

[0038] The AC triboelectric signal output from the triboelectric nanogenerator unit is fed into a triboelectric rectifier bridge and rectified into DC power by diodes. The AC induced current output from induction coil 7 is fed into an electromagnetic rectifier bridge and also rectified into DC power by diodes. The two DC power sources are connected in parallel on the DC side and then fed into an energy storage capacitor for energy harvesting and voltage smoothing. Subsequently, a low-dropout linear regulator is used for voltage stabilization and step-down processing to stabilize the voltage within the operating voltage range required by the external load. Finally, a stable DC voltage is output through a collector ring, achieving power superposition and complementary advantages of high-voltage triboelectric nanogenerator and high-current electromagnetic generator. As a preferred embodiment of the present invention, the outer rotor 1 and the inner stator 2 are made of transparent acrylic or insulating resin material, and the comb-shaped copper electrodes 5 are attached to or embedded in the inner wall of the outer rotor 1 by flexible circuit technology.

[0039] The outer rotor 1 and inner stator 2 are made of transparent acrylic or insulating resin, which has excellent insulation properties and can effectively prevent leakage between the comb-shaped copper electrode 5, the induction coil 7 and the substrate, ensuring charge collection efficiency and power transmission stability. Moreover, the material is lightweight, which can reduce the overall mass of the outer rotor 1, reduce the wind energy threshold required for the wind cup 3 to drive the outer rotor 1 to rotate, and improve the utilization efficiency of weak wind energy. In addition, the processing and molding are easy, making it easy to make into a ring structure that matches the ball bearing, and it can adapt to the assembly requirements of flexible circuit technology, ensuring the attachment or embedding accuracy of the comb-shaped copper electrode 5.

[0040] The permanent magnet array 6 is arranged at uniform intervals along the circumference of the inner stator 2, and the magnetic field direction of the permanent magnet array 6 is perpendicular to the axial direction of the induction coil 7.

[0041] A parameter optimization design method for a ball bearing-type friction-electromagnetic composite energy harvesting system includes the following steps: S1. Establish a multiphysics finite element simulation model that includes the structure of rolling element 4, comb-shaped copper electrode 5, inner ring stator 2 and outer ring rotor 1, and use surface charge density as boundary condition to simulate the dynamic sensing process of the relative rotation of the PTFE rolling element 4 and the comb-shaped copper electrode 5. S2. Using the diameter of the rolling element 4, the radial gap between the rolling element 4 and the comb-shaped copper electrode 5, and the central angle of the comb-shaped copper electrode 5 as optimization variables, the influence of each variable on the system output potential and induced charge density is obtained through simulation. S3. Determine the optimal parameters based on the simulation results: the diameter of the rolling element 4 is taken as the maximum allowable value of the bearing structure composed of the inner ring stator 2 and the outer ring rotor 1; the radial clearance between the rolling element 4 and the comb-shaped copper electrode 5 is controlled within 0.1mm; and the central angle of the comb-shaped copper electrode 5 is taken as the angle corresponding to the system output power balance point. S4. Connect the output terminal of the comb-shaped copper electrode 5 of the triboelectric nanogenerator unit to the triboelectric rectifier bridge of the rotor-side energy management unit 8, and connect the output terminal of the induction coil 7 to the electromagnetic rectifier bridge of the rotor-side energy management unit 8. Utilize the unidirectional conduction characteristic of the diode to achieve impedance isolation between the two power supplies. After rectification, the two power supplies are connected in parallel on the DC side, and after energy storage by the energy storage capacitor and voltage regulation by the low-dropout linear regulator, a stable DC voltage is output through the collector ring.

[0042] In step S1, the multiphysics finite element simulation model needs to simulate the motion state of the outer ring rotor 1 driving the rolling element 4 to rotate around the inner ring stator 2, and simultaneously simulate the triboelectric charging process of the triboelectric nano-power generation unit and the electromagnetic induction process of the electromagnetic power generation unit to ensure that the simulation results are consistent with the actual working state.

Claims

1. A ball bearing type triboelectric-electromagnetic composite energy harvesting system, characterized in that: It includes an inner ring stator (2) and an outer ring rotor (1) coaxially rotatably connected to the inner ring stator (2). An installation rod is fixedly connected radially to the outer side wall of the outer ring rotor (1). An induction coil (7) is wound on the installation rod. A wind cup (3) is fixed to the outer end of the installation rod. A permanent magnet array (6) is installed inside the inner ring stator (2). A triboelectric nanogenerator unit is set at the gap between the inner ring stator (2) and the outer ring rotor (1). A collector ring electrically connected to the induction coil (7) and the triboelectric nanogenerator unit is installed on the outer side of the inner ring stator (2).

2. The ball bearing type triboelectric-electromagnetic composite energy harvesting system as described in claim 1, characterized in that: The triboelectric nanogenerator unit includes several rolling elements (4) that can be rolled between the inner stator (2) and the outer rotor (1), and a comb-shaped copper electrode (5) fixed to the inner sidewall of the outer rotor (1). The rolling elements (4) are made of PTFE material.

3. The ball bearing type triboelectric-electromagnetic composite energy harvesting system as described in claim 2, characterized in that: The comb-shaped copper electrode (5) includes two sets of interlocking but non-contacting comb electrode plates (51), the number of comb teeth of the two sets of comb electrode plates (51) being equal to or an integer multiple of the number of rolling elements (4).

4. The ball bearing type triboelectric-electromagnetic composite energy harvesting system as described in claim 2, characterized in that: The gap between the rolling element (4) and the comb-shaped copper electrode (5) along the radial direction of the outer ring rotor (1) is no more than 0.1 mm. Welded fixing structures are provided between the top two sides of the rolling element (4) and the inner wall of the outer ring rotor (1).

5. The ball bearing type triboelectric-electromagnetic composite energy harvesting system as described in claim 1, characterized in that: A rotor-side energy management unit (8) is installed on the outer side wall of the outer ring rotor (1). The output ends of the comb-shaped copper electrode (5) of the triboelectric nanogenerator and the induction coil (7) are electrically connected to the rotor-side energy management unit (8). The rotor-side energy management unit (8) is electrically connected to the collector ring.

6. The ball bearing type triboelectric-electromagnetic composite energy harvesting system as described in claim 5, characterized in that: The rotor-side energy management unit (8) includes a triboelectric rectifier bridge and an electromagnetic rectifier bridge that are independent of each other. The triboelectric rectifier bridge is connected to the comb-shaped copper electrode (5), and the electromagnetic rectifier bridge is connected to the induction coil (7). Both the triboelectric rectifier bridge and the electromagnetic rectifier bridge are equipped with diodes for impedance isolation.

7. The ball bearing type triboelectric-electromagnetic composite energy harvesting system as described in claim 1, characterized in that: The outer ring rotor (1) and the inner ring stator (2) are made of transparent acrylic or insulating resin material, and the comb-shaped copper electrode (5) is attached to or embedded in the inner wall of the outer ring rotor (1) by flexible circuit technology.

8. The ball bearing type triboelectric-electromagnetic composite energy harvesting system as described in claim 1, characterized in that: The permanent magnet array (6) is arranged at uniform intervals along the circumference of the inner stator (2), and the magnetic field direction of the permanent magnet array (6) is perpendicular to the axial direction of the induction coil (7).

9. A parameter optimization design method for a ball bearing-type triboelectric-electromagnetic composite energy harvesting system according to any one of claims 1-8, characterized in that, Includes the following steps: S1. Establish a multiphysics finite element simulation model containing a rolling element (4), a comb-shaped copper electrode (5), an inner ring stator (2) and an outer ring rotor (1). Use surface charge density as the boundary condition to simulate the dynamic sensing process of the relative rotation between the PTFE rolling element (4) and the comb-shaped copper electrode (5). S2. Using the diameter of the rolling element (4), the radial gap between the rolling element (4) and the comb-shaped copper electrode (5), and the central angle of the comb-shaped copper electrode (5) as optimization variables, the influence of each variable on the system output potential and induced charge density is obtained through simulation. S3. Determine the optimal parameters based on the simulation results: the diameter of the rolling element (4) is taken as the maximum value allowed by the bearing structure composed of the inner ring stator (2) and the outer ring rotor (1); the radial clearance between the rolling element (4) and the comb-shaped copper electrode (5) is controlled within 0.1mm; and the central angle of the comb-shaped copper electrode (5) is taken as the angle corresponding to the system output power balance point. S4. Connect the output terminal of the comb-shaped copper electrode (5) of the triboelectric nanogenerator unit to the triboelectric rectifier bridge of the rotor-side energy management unit (8), and connect the output terminal of the induction coil (7) to the electromagnetic rectifier bridge of the rotor-side energy management unit (8). Utilize the unidirectional conduction characteristic of the diode to achieve impedance isolation between the two power supplies. After rectification, the two power supplies are connected in parallel on the DC side, and after energy storage by the energy storage capacitor and voltage regulation by the low-dropout linear regulator, a stable DC voltage is output through the collector ring.

10. The parameter optimization design method as described in claim 9, characterized in that: In step S1, the multiphysics finite element simulation model needs to simulate the motion state of the outer ring rotor (1) driving the rolling body (4) to rotate around the inner ring stator (2), and simultaneously simulate the triboelectric process of the triboelectric nano-power generation unit and the electromagnetic induction process of the electromagnetic power generation unit to ensure that the simulation results are consistent with the actual working state.

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