Frequency up-conversion piezoelectric-electromagnetic hybrid energy harvester for ultra-small displacement input

Abstract

The present invention discloses a frequency up-conversion piezoelectric-electromagnetic hybrid energy collector for ultra-small displacement input, including a flexible amplification mechanism, a transmission mechanism, and a power generation mechanism; the flexible amplification mechanism includes two straight beam flexible hinges, two semicircular flexible hinges, a symmetrical flexible hinge, and corresponding rigid connection components and support rods; the transmission mechanism includes a ball screw, a one-way bearing, a gear pair, a seat bearing, and a corresponding transmission shaft; the two components of the power generation mechanism both use frequency up-conversion technology, one part is an electromagnetic power generation mechanism composed of a magnet on the edge of the flywheel and an induction coil on the support plate; the other part is a piezoelectric mechanism composed of a piezoelectric cantilever beam clamped on the support rod and a toggle block embedded in the ball screw nut. The present invention integrates electromagnetic-piezoelectric hybrid power generation technology, realizes bidirectional and efficient recovery and storage of vibration energy with low gap loss under micro-displacement input, and has broad application prospects.

Description

Technical Field

[0001] The invention belongs to the technical field of micro sensors, and in particular relates to a bidirectional frequency up-conversion energy collector. Background Art

[0002] In the past two decades, research on energy collectors for orbital vibration energy harvesting has attracted more and more attention. The power generation methods of these energy collectors are mainly electromagnetic, piezoelectric, hydraulic and triboelectric. The research in this field of energy collectors is mainly focused on piezoelectric and electromagnetic forms, accounting for more than 90% of the total research.

[0003] Among them, the piezoelectric material can be divided into a compression type and a bending type according to the different deformations produced when the wheel-rail force acts on the piezoelectric material. On the one hand, the compression type piezoelectric harvester uses the compression deformation caused by the downward pressure of the rail when the train passes to harvest energy. On the other hand, the bending type piezoelectric harvester mainly attaches the piezoelectric material to the bottom of the rail or the root of the cantilever beam. When the rail or cantilever beam is deformed, the piezoelectric sheet completes energy harvesting due to the strain. However, conventional piezoelectric energy collectors are suitable for working in a higher frequency range, and the output in a low-frequency environment is not ideal. Further, in terms of electromagnetic energy collectors that are more suitable for low-frequency environments, they can be mainly divided into linear vibration type and rotation type according to the form of movement. For rotary electromagnetic energy collectors, they have received more attention due to their higher power output (watt level). Rotary electromagnetic energy collectors mainly utilize the large load characteristics of track vibration, and convert the low-frequency linear vibration of the track into rapid rotational motion through a transmission mechanism. As for the electromagnetic energy collectors currently used for track vibration, almost all electromagnetic rotary energy collectors based on gear racks require a large displacement input (2.75-12.7mm). However, the vertical displacement of the most widely used continuous welded ballastless track in high-speed railway transportation is often less than 2mm. However, the gear clearance of the gear rack transmission mechanism will seriously affect the mechanical efficiency when the displacement input is less than 2mm, especially when collecting track vibration energy with pulse characteristics. In addition, most energy collectors have a single energy conversion method and the power generation is too dependent on the train speed.

[0004] Therefore, in order to overcome the above problems, enable the energy collector to achieve ideal effects in various applications and further expand its application fields, it is necessary to design a bidirectional frequency up-conversion energy collector that can amplify the excitation displacement and realize piezoelectric-electromagnetic hybrid energy harvesting. Summary of the invention

[0005] The purpose of the present invention is to overcome the deficiencies of the prior art and to provide a bidirectional frequency up-conversion energy collector with a compact structure, reliable performance, high energy recovery efficiency and an optimized design based on practical applications and a good foundation.

[0006] The object of the present invention is achieved through the following technical solutions: a frequency up-conversion piezoelectric-electromagnetic hybrid energy collector for ultra-small displacement input, including a flexible amplification mechanism, a transmission mechanism, a power generation mechanism and other mechanisms that play a supporting and fixing role;

[0007] The flexible amplification mechanism includes two straight beam flexible hinges, two semicircular flexible hinges, and one symmetrical flexible hinge; one end of the two straight beam flexible hinges is connected to the supporting top plate by bolts, and the other end is connected to the semicircular flexible hinge and the symmetrical flexible hinge by bolts; the other end of the semicircular flexible hinge is connected to the supporting beam by bolts; one end of the symmetrical flexible hinge is connected to the straight beam flexible hinge, and the other end is clamped on the lead screw.

[0008] The transmission mechanism includes a lead screw, a lead screw nut, a driving shaft, two one-way bearings in different directions, two driving gears, a pair of driven gears, and a pair of driven shafts; one end of the lead screw is installed on a symmetrical flexible hinge, and the other end is connected to the driving shaft through a lead screw nut; the other end of the driving shaft is installed on a supporting base plate; the two driving gears are installed in cooperation with the driving shaft through one-way bearings in different directions, and respectively meet the gear meshing relationship with the two driven gears at different heights; the driven gear is installed on the driven shaft; the driven shaft is fixed to the supporting base plate through a fixing frame, and the upper end is connected to the flywheel.

[0009] The power generation mechanism includes a first power generation mechanism and two second power generation mechanisms; the toggle block is nested on the lead screw nut, the piezoelectric cantilever beam is installed on the support beam, and the piezoelectric cantilever beam has a piezoelectric sheet, forming the first power generation mechanism; the flywheel is connected to the driven shaft, and multiple magnets are installed on it, and the coil is fixed by a coil fixing plate, forming the second power generation mechanism.

[0010] Furthermore, the flexible amplification mechanism can amplify external micro-displacement excitation without gap.

[0011] Furthermore, the transmission mechanism can convert the axial movement of the lead screw into the rotational movement of the driving shaft. When the lead screw moves downward, the driving shaft is coupled with the upper driving gear through the one-way bearing, driving the left driven gear of the energy collector to rotate; when the lead screw moves upward, the driving shaft is coupled with the lower driving gear through the one-way bearing, driving the right driven gear of the energy collector to rotate.

[0012] Furthermore, in the first power generation mechanism, the toggle block rotates as the lead screw nut rotates, and each toggle block can toggle the piezoelectric cantilever beam to generate deformation, thereby utilizing the piezoelectric effect to convert deformation energy into electrical energy for storage.

[0013] Furthermore, the magnet in the second power generation mechanism is fixed on the flywheel and can rotate with the flywheel, generating relative rotation with the fixed coil, thereby utilizing the law of electromagnetic induction to convert kinetic energy into electrical energy for storage. Furthermore, the pair of driven gears are symmetrically distributed about the support beam, and the driven gears on both sides are only slightly different in height.

[0014] The beneficial effects of the present invention are as follows: the present invention has a compact structure and reliable performance. When used for vibration energy recovery, the micro-displacement excitation can be amplified, and the axial motion can be converted into rotational motion through the ball screw mechanism. Compared with the rack transmission, the energy loss caused by the structural gap can be greatly reduced. Furthermore, the present invention adopts a two-way energy collection method. When the screw moves downward and upward, it is coupled with one of the two active gears respectively, avoiding the efficiency loss problem caused by ordinary mechanical rectification. Furthermore, the present invention converts the low-frequency vibration of the track into high-frequency resonance of the piezoelectric beam by nesting the toggle blocks, thereby improving the energy recovery efficiency. The present invention has high integration, high energy recovery efficiency, high applicability, and broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 It is a structural schematic diagram of the energy collector of the present invention;

[0016] Figure 2 It is a schematic diagram of the flexible amplification mechanism and the first power generation mechanism of the energy collector of the present invention;

[0017] Figure 3 is a working flow chart of the energy collector of the present invention;

[0018] Figure 4 The rigid-flexible coupling dynamics model of the energy collector of the present invention;

[0019] Description of the reference numerals: 1-support top plate, 2-straight beam flexible hinge, 3-semicircular flexible hinge, 4-symmetrical flexible hinge. 5-screw, 6-screw nut, 7-sliding block, 8-piezoelectric cantilever beam, 9-one-way bearing, 10-driving shaft, 11-support beam, 12-support bottom plate, 13-driving gear, 14-driven gear, 15-fixed frame, 16-driven shaft, 17-flywheel, 18-magnet, 19-coil, 20-piezoelectric sheet, 21-coil fixing plate. DETAILED DESCRIPTION

[0020] The technical solution of the present invention is further described below in conjunction with the accompanying drawings.

[0021] like Figure 1 , Figure 2 As shown, a frequency up-conversion piezoelectric-electromagnetic hybrid energy collector for ultra-small displacement input includes a flexible amplification mechanism, a transmission mechanism, a power generation mechanism, and other mechanisms that play a supporting and fixing role;

[0022] The flexible amplification mechanism includes two straight beam flexible hinges 2, two semicircular flexible hinges 3, and a symmetrical flexible hinge 4; one end of the two straight beam flexible hinges 2 is connected to the supporting top plate 1 by bolts, and the other end is connected to the semicircular flexible hinge 3 and the symmetrical flexible hinge 4 by bolts; the other end of the semicircular flexible hinge 3 is connected to the supporting beam 11 by bolts; one end of the symmetrical flexible hinge 4 is connected to the straight beam flexible hinge 2, and the other end is clamped on the screw 5.

[0023] The transmission mechanism includes a screw 5, a driving shaft 10, a screw nut 6, two one-way bearings 9 in different directions, a pair of driving gears 13, a pair of driven gears 14, and a pair of driven shafts 16; one end of the screw 5 is installed on the symmetrical flexible hinge 4, and the other end is connected to the driving shaft 10 through the screw nut 6; the other end of the driving shaft 10 is installed on the supporting base plate 12; the two driving gears 13 are installed in cooperation with the driving shaft 10 through the one-way bearings 9 in different directions, and respectively meet the gear meshing relationship with the pair of driven gears 14; the driven gears 14 are installed on the driven shaft 16 in a one-to-one correspondence; the driven shaft 16 is fixed to the supporting base plate 12 through the fixing frame 15, and the upper end is connected to the respective flywheels 17.

[0024] The power generation mechanism includes a toggle block 7, a piezoelectric sheet 20, a piezoelectric cantilever beam 8, a flywheel 17, a coil 19, and a magnet 18; the toggle block 7 is nested on the lead screw nut 6, the piezoelectric cantilever beam 8 is installed on the support beam 11, and the piezoelectric cantilever beam 8 has piezoelectric sheets 20 arranged in an array, forming a first power generation mechanism; the flywheel 17 is connected to the driven shaft 16, on which a plurality of magnets 18 are installed, and the coil 19 is fixed by a coil fixing plate 21, forming a second power generation mechanism.

[0025] Furthermore, the flexible amplification mechanism can amplify the external micro-displacement excitation without gap, so as to reduce the inherent gap of the subsequent conventional transmission mechanism and the adverse effects caused by the structural stress and deformation caused by long-term operation and temperature changes.

[0026] Furthermore, the transmission mechanism can convert the axial reciprocating motion of the screw 5 into two unidirectional rotational motions of the driving shaft 10. When the screw 5 moves downward, the driving shaft 10 and the upper driving gear 13 are coupled to drive the driven gear on the left side of the energy collector to rotate; when the screw 5 moves from bottom to top, the driving shaft 10 and the lower driving gear 13 are coupled to drive the driven gear on the right side of the energy collector to rotate. This method realizes the conversion of bidirectional linear motion into unidirectional rotation of two driving gears 13 in opposite directions, avoiding the energy loss caused by the reversal of the single flywheel 17 due to the reciprocating motion of the screw 5, while reducing the transmission impact and increasing the service life of the energy collector.

[0027] Furthermore, the magnet 18 is fixed on the flywheel 17, and can rotate with the flywheel 17, and generate relative rotation with the fixed coil 19. At the same time, the flywheel 17 is used to store the mechanical energy transmitted by the transmission mechanism, and the rapid rotation of the flywheel 17 realizes the frequency conversion effect of the rapid change of the magnetic flux, thereby converting the mechanical energy into electrical energy, and realizing the continuous collection, storage and stable output of the track impact energy.

[0028] Furthermore, in the first power generation mechanism, the toggle block 7 rotates with the rotation of the screw nut 6, and each toggle block 7 can cause the piezoelectric cantilever beam 8 to deform. At the same time, due to the large load characteristics of the track vibration, the intervention of the first power generation mechanism does not affect the energy collection of the second power generation mechanism, and finally realizes the conversion of the low-frequency vibration input decoupled from the second power generation mechanism into high-frequency resonant power generation.

[0029] Furthermore, the energy collector is symmetrically distributed about the support beam 11 except for the driven gears 14 on both sides, and the driven gears 14 on both sides are only slightly different in height, so as to realize the double energy collection mechanism to fully collect the bidirectional vibration energy, which will effectively utilize the large load characteristics of rail vibration (>100KN).

[0030] The working principle of the present invention is: Figure 3 As shown, the support top plate fixedly connected to the rail receives the vibration excitation of the rail, amplifies the vertical displacement through the flexible amplification mechanism, and then transmits it to the lead screw 5 of the ball screw. The up and down movement of the lead screw 5 causes the lead screw nut 6 to drive the transmission shaft to rotate clockwise and counterclockwise, and then transmits power through two one-way bearings 9 in opposite directions, so that the two driving gears 13 make one-way rotations in different directions to realize the power transmission between the driven shaft 16 and the flywheel 17. It is worth noting that due to the effect of the one-way bearing 9, when the lead screw 5 moves downward, the transmission shaft can drive the gear to rotate counterclockwise, but when it moves upward, it cannot drive the gear to rotate and change direction, so that the flywheel 17 can maintain free rotation in the clockwise direction. Figure 1In the structural diagram shown, when the lead screw 5 moves downward, it will only drive the upper active gear 13 to rotate counterclockwise, and when the lead screw 5 moves upward, it will only drive the lower active gear 13 to rotate clockwise, so that the flywheels 17 on the left and right sides respectively maintain continuous rotation clockwise and counterclockwise, and realize the storage of track impact energy while collecting and completing the bidirectional vibration energy, thereby realizing efficient energy collection and improving the smoothness of the energy collector output and the robustness of the system. At the same time, for the piezoelectric cantilever beam 8, whether the rail vibration is upward or downward, the toggle block 7 on the lead screw nut 6 can toggle it to generate electricity. The thrust of the toggle block 7 causes the piezoelectric cantilever beam 8 to deflect. In this process, kinetic energy is stored as deformation potential energy. After separation, the piezoelectric cantilever beam 8 oscillates freely at its natural frequency, and the piezoelectric ceramic quickly converts the deformation energy into electrical energy output. This is a frequency up-conversion method that quickly releases the energy in low-frequency excitation through high-frequency oscillation to increase power output. The adoption of this method widens the operating frequency range of the energy collector, which is superior to conventional low-frequency piezoelectric energy collectors. More importantly, the large load characteristics of track vibration decouple the two power generation mechanisms from each other, further improving the energy collection efficiency.

[0031] Figure 4 The rigid-flexible coupling dynamic model of the proposed energy collector is presented. The energy collector can be regarded as a multi-rigid body transmission mechanism, and the flexible hinge mechanism is equivalent to a simplified model of a spring connected to a lever. The lever amplifies the input rail displacement and outputs it to the screw 5. The ball screw converts linear motion into rotational motion, so that the driving shaft 10 rotates clockwise and counterclockwise as the excitation displacement changes. Due to the presence of the one-way bearing 9, the torque can only be transmitted from the driving shaft 10 to the driven shaft 16 when the driving shaft 10 is in the same direction as the driving gear 13 and the angular velocity is equal to that of the driving gear 13. In other cases, the driven shaft 16 and the flywheel 17 maintain free rotation due to inertia.

[0032] The frequency up-conversion piezoelectric-electromagnetic hybrid energy collector for ultra-small displacement input proposed by the present invention can realize efficient energy extraction under small amplitude, low frequency and large load excitation conditions. The device has a flexible amplification mechanism without mechanical friction, high precision, and can effectively avoid the working gap problem of rigid transmission mechanisms such as gear racks, that is, a primary transmission mechanism, which can realize gapless amplification of small displacements, and can effectively reduce the adverse effects caused by the gap of the subsequent transmission when the amplified displacement input is transmitted to the conventional subsequent transmission structure. Then, the structure of the lead screw 5, the lead screw nut 6 and the two one-way bearings 9 can realize the one-way transmission of power. At the same time, the toggle block 7 nested on the lead screw nut 6 can also convert the low-frequency excitation into the high-frequency resonance of the piezoelectric beam to realize efficient energy collection. Finally, the force is transmitted to the flywheel 17 by gear transmission, and the flywheel 17 drives the magnet 18 to rotate, and the cutting coil 19 generates electrical energy, realizing the decoupled energy collection from the first power generation mechanism while storing and extracting the impact energy of the track, thereby improving the energy collection efficiency and the stability and robustness of the energy collector.

[0033] The frequency up-conversion piezoelectric-electromagnetic hybrid energy collector proposed in the present invention for ultra-small displacement input can not only complete the low-frequency and small-amplitude energy extraction of most tracks compared to conventional energy collectors, but also greatly reduce the energy storage waste and structural impact caused by the reversal of the flywheel 17 following the vibration direction due to the use of two-way energy collection. In addition, the electromagnetic-piezoelectric hybrid energy collection technology is also applied. Due to the large load characteristics of track vibration, the electromagnetic power generation unit and the piezoelectric power generation unit are connected in parallel, and the two are decoupled, which greatly increases the total value of extracted energy while achieving continuous output. Therefore, its energy recovery efficiency and average power of output electric energy are higher than those of ordinary energy harvesters. It has been verified that the collected electric energy can power components such as micro sensors.

[0034] Those skilled in the art will appreciate that the embodiments described herein are intended to help readers understand the principles of the present invention, and should be understood that the protection scope of the present invention is not limited to such specific statements and embodiments. Those skilled in the art can make various other specific variations and combinations that do not deviate from the essence of the present invention based on the technical revelations disclosed by the present invention, and these variations and combinations are still within the protection scope of the present invention.

Claims

1. A frequency up-conversion piezoelectric-electromagnetic hybrid energy collector for ultra-small displacement input, characterized in that: It includes a flexible amplification mechanism, a transmission mechanism, and a power generation mechanism; The flexible amplification mechanism is used to amplify the external micro-displacement excitation without gap; The transmission mechanism comprises a lead screw (5), a driving shaft (10), a lead screw nut (6), two one-way bearings (9) in different directions, two driving gears (13), a pair of driven gears (14), and a pair of driven shafts (16); one end of the lead screw (5) is mounted on the flexible amplification mechanism, and the other end is connected to the driving shaft (10) through the lead screw nut (6); the other end of the driving shaft (10) is mounted on the supporting base plate (12); the two driving gears (13) are respectively mounted on the driving shaft (10) through two one-way bearings (9) in different directions, and the two driving gears (13) respectively meet the gear meshing relationship with the pair of driven gears (14) at different heights; the driven gears (14) are mounted on the driven shafts (16) in a one-to-one correspondence; the pair of driven shafts (16) are respectively fixed to the supporting base plate (12) through a fixing frame (15), and the upper end of each driven shaft (16) is connected to a flywheel (17); The power generation mechanism comprises a first power generation mechanism and two second power generation mechanisms; the toggle block (7) is nested on the lead screw nut (6), the piezoelectric cantilever beam (8) is mounted on the support beam (11), and a piezoelectric sheet (20) is disposed on the piezoelectric cantilever beam (8), forming the first power generation mechanism; the flywheel (17) is connected to the driven shaft (16), a plurality of magnets (18) are mounted on the flywheel, and the coil (19) is fixed by a coil fixing plate (21), forming the second power generation mechanism; The flexible amplification mechanism comprises two straight beam flexible hinges (2), two semicircular flexible hinges (3), and a symmetrical flexible hinge (4); one end of the two straight beam flexible hinges (2) is connected to the support top plate (1) by bolts, and the other end is connected to the semicircular flexible hinge (3) and the symmetrical flexible hinge (4) by bolts; the other end of the semicircular flexible hinge (3) is connected to the support beam (11) by bolts; one end of the symmetrical flexible hinge (4) is connected to the straight beam flexible hinge (2), and the other end is clamped on the lead screw (5).

2. The frequency up-conversion piezoelectric-electromagnetic hybrid energy collector for ultra-small displacement input according to claim 1, characterized in that: The pair of driven gears (14) are symmetrically distributed with respect to the support beam (11).

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