Knee joint driven piezoelectric permanent magnet composite multi-vibrator energy harvesting system

Abstract

The present invention relates to the field of energy electromechanical conversion technology, a knee joint driven piezoelectric permanent magnet composite multi-vibrator energy collection system, wherein the first fixed arm is connected to the main shaft, the external fixed support is mounted on the main shaft and rotates with the main shaft; the end of the second fixed arm is connected to the external fixed support, the shell is connected to the main shaft and rotates with the main shaft; a plurality of piezoelectric substrates are installed on the main shaft in the shell, two fixed magnets are installed at the free end of the piezoelectric substrate, a moving magnet is installed near the piezoelectric substrate at the inner end face of the shell, and the moving magnets are arranged in a ring with the axis of the main shaft as the rotation center, and the polarities of two adjacent moving magnets are opposite; the polarities of the fixed magnets on the same side of the plurality of piezoelectric substrates are the same, and opposite to the polarities of the fixed magnets on the other side of the piezoelectric substrate. The energy collection system works stably and reliably, and has low processing, use and maintenance costs, and focuses on solving how to realize magnetically excited vibration energy collection when the human body walks.

Description

Technical Field

[0001] The present invention relates to the technical field of energy electromechanical conversion, in particular to a knee joint driven piezoelectric permanent magnet composite multi-vibrator energy collection system. Background Art

[0002] In recent years, the global demand for small electronic devices has continued to grow across various fields. Most sensors and small electronic devices rely primarily on batteries for power. However, for military electronic devices and wearable devices, carrying batteries is impractical due to their prolonged use in outdoor environments. Therefore, innovative equipment is needed to achieve a continuous energy supply.

[0003] Research has shown that vibration energy harvesting systems achieve the highest energy conversion efficiency when the external vibration frequency matches the system's natural frequency. However, in practical applications, the external vibration frequency may have a wide frequency band, with significant dispersion across different applications. Furthermore, the external vibration excitation frequency can change over time within the same application. This places a high demand on vibration energy harvesters for a wide frequency band, requiring them to have high energy conversion efficiency across a wide frequency band.

[0004] At present, most vibration energy harvesting structures increase the area of ​​the piezoelectric layer in the length or width direction, which leads to a reduction in the compactness of the collector and is not conducive to portability requirements. In addition, most existing vibration energy harvesting structures have disadvantages such as a single application environment and poor portability. This design can be applied in multiple fields, has a high degree of lightweight, high structural strength and strong maintainability, and can make corresponding adjustments for different application scenarios. Summary of the Invention

[0005] To solve the above problems, the present invention proposes a knee joint-driven piezoelectric permanent magnet composite multi-vibrator energy harvesting system, which has stable and reliable operation and low processing, use and maintenance costs. It focuses on how to realize magnetically excited vibration energy harvesting when the human body walks.

[0006] To achieve the above object, the technical solution adopted by the present invention is:

[0007] A knee joint driven piezoelectric permanent magnet composite multi-vibrator energy harvesting system is characterized by comprising a first fixed arm, a housing, a second fixed arm, an external fixed support, a main shaft, and a unidirectional drive mechanism, wherein the first fixed arm is connected to the main shaft, the external fixed support is connected to the end of the second fixed arm, the external fixed support is sleeved on the main shaft and rotatably connected to the main shaft, and the housing is rotatably mounted on the main shaft;

[0008] A plurality of piezoelectric matrixes are mounted on the main shaft, and the main extension surface of the piezoelectric matrix is ​​perpendicular to the main shaft, the root of the piezoelectric matrix is ​​connected to the main shaft, and the plurality of piezoelectric matrixes are equidistant and radially arranged with the axis of the main shaft as the center, two fixed magnets are mounted on both sides of the free end of each of the piezoelectric matrixes, the end faces of both ends of the inner side of the shell are close to the piezoelectric matrix, a plurality of spaced moving magnets are arranged on the inner end face of the shell, and the plurality of moving magnets are arranged in a ring with the axis of the main shaft as the rotation center, the polarities of two adjacent moving magnets are opposite, and the polarities of the fixed magnets on the first side of the plurality of piezoelectric matrixes are the same, and the polarities of the fixed magnets on the second side of the piezoelectric matrixes are the same and opposite to those of the fixed magnets on the first side;

[0009] The unidirectional driving mechanism is mounted on an external fixed support and can drive the shell to rotate unidirectionally, so that the staggered moving magnetic poles in the shell form a continuous sinusoidal excitation on the fixed magnet on the piezoelectric matrix, so that the piezoelectric matrix generates electricity.

[0010] Preferably, both ends of the main shaft have a spline structure, and an external fixed arm is installed on the side of the first fixed arm facing the main shaft. The external fixed arm is an "L"-shaped structure, and the end of the first fixed arm and the external fixed arm form a "U"-shaped structure. The two ends of the "U"-shaped structure are fixedly connected to the main shaft through a spline structure.

[0011] Preferably, the first end of the shell is mounted on the main shaft through a first bearing, the second end of the shell is mounted on the main shaft through a third bearing, the end of the second fixed arm has an annular structure, and the annular structure of the second fixed arm is connected to the second end of the shell through a second bearing.

[0012] Preferably, the external fixed support also has a mounting plate for mounting the one-way drive mechanism, the mounting plate is rotatably connected to the main shaft through a flange bearing, the inner side of the mounting plate faces the shell, and the one-way drive mechanism is mounted on the side of the one-way drive mechanism facing the shell.

[0013] Preferably, the shell has a ratchet on the side facing the mounting plate, and the mounting plate has a pawl on the side facing the ratchet. The tail of the pawl is rotatably mounted on the mounting plate through a positioning shaft. The inner side of the mounting plate also has a tension spring, and the two ends of the tension spring are respectively connected to the mounting plate and the front of the pawl, so that the pawl is always pressed on the tooth structure of the ratchet.

[0014] Preferably, the diameter of the middle portion of the spindle is larger than the diameter of the main spindle body and forms a cylindrical structure, the cylindrical structure is provided with a plurality of long strip-shaped mounting grooves, the mounting grooves extend annularly along the cylindrical structure, slots are provided on both sides of each group of mounting grooves, and the mounting groove body extends axially along the cylindrical structure;

[0015] The root of the piezoelectric matrix is ​​inserted into the installation groove, and blocking pieces are provided on both sides of the piezoelectric matrix, and the roots of the blocking pieces are inserted into the slots.

[0016] Preferably, the piezoelectric substrate and two baffles adjacent to the piezoelectric substrate form a piezoelectric cantilever beam with an "H"-shaped cross section.

[0017] Preferably, the slot is an "L"-shaped structure, and the bottom of the slot extends vertically away from the mounting slot; one end of the slot passes through the first end of the cylindrical structure; the piezoelectric matrix has a mounting hole, and the end face of the first end of the cylindrical structure is provided with a mounting hole for fixing the root of the piezoelectric matrix.

[0018] Preferably, the cylindrical structure also has a gasket and a locking plate on both sides, which connect and position the piezoelectric matrix and the baffle by screws passing through the hole interface at the tail of the piezoelectric matrix, the mounting hole on the cylindrical structure, and the gasket and the locking plate.

[0019] Preferably, the first fixing arm and the second fixing arm are both provided with straps; the first fixing arm and the second fixing arm are both bent to a certain extent to adapt to being worn on the thigh and calf of the human body; and the main shaft also has a threading hole.

[0020] The beneficial effects of using the present invention are:

[0021] This collecting device can be worn on the human leg. Through the movement of the thigh and calf, the shell is driven to rotate around the main axis with the main axis as the center, and then the moving magnet rotates around the fixed rotation axis. Through the cooperation of the moving magnet and the fixed magnet, that is, the fixed magnet is continuously sinusoidally excited by the moving magnetic pole, the piezoelectric matrix generates electricity.

[0022] This collection device optimizes the structure and installation method of the piezoelectric cantilever beam, and weakens the complex deformation of the cantilever beam through baffle constraints, avoiding the situation where the sinusoidal excitation effect changes due to deformation caused by the cantilever beam's complex receiving force.

[0023] The device has been structurally optimized, with an integrated spindle design for easy maintenance and disassembly. The compact structure and lightweight design of the system make it more wearable. Modifications to the device can also be used on other devices, making it highly portable. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 Axonometric view of the piezoelectric permanent magnet composite multi-vibrator energy harvesting system for knee joint drive.

[0025] Figure 2 Schematic diagram of the main axis of the piezoelectric permanent magnet composite multi-vibrator energy harvesting system device for knee joint driving.

[0026] Figure 3 Schematic diagram of the ratchet structure of the knee joint driven piezoelectric permanent magnet composite multi-vibrator energy harvesting system.

[0027] Figure 4 Schematic diagram of the shell structure of the knee joint driven piezoelectric permanent magnet composite multi-vibrator energy harvesting system device.

[0028] Figure 5 Schematic diagram of the internal structure of the shell of the knee joint drive piezoelectric permanent magnet composite multi-vibrator energy harvesting system device.

[0029] Figure 6 This is a schematic diagram of the connection method of each bearing in the knee joint driven piezoelectric permanent magnet composite multi-vibrator energy harvesting system device.

[0030] Reference numerals include:

[0031] 1-first fixed arm, 2-external fixed arm, 3-housing, 4-external fixed support, 5-second fixed arm, 6-binding strap, 7-spindle, 8-mounting slot, 9-slot, 10-threading hole, 11-threading hole, 12-tension spring, 13-pawl, 14-outer housing, 15-inner housing, 16-flange bearing, 17-gasket, 18-locking plate, 19-blocking plate, 20-piezoelectric matrix, 21-moving magnet, 22-fixed magnet, 23-first bearing, 24-flange bearing outer ring, 25-sleeve, 26-second bearing, 27-third bearing. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solution and advantages of this technical solution more clear, the following technical solution is further described in detail in conjunction with specific implementation methods. It should be understood that these descriptions are only exemplary and are not intended to limit the scope of this technical solution.

[0033] like Figures 1-6As shown, the knee joint driven piezoelectric permanent magnet composite multi-vibrator energy harvesting system includes a first fixed arm 1, a shell 3, a second fixed arm 5, an external fixed support 4, a main shaft 7 and a unidirectional driving mechanism, wherein the first fixed arm 1 is connected to the main shaft 7, the external fixed support 4 is connected to the end of the second fixed arm 5, the external fixed support 4 is sleeved on the main shaft 7 and rotatably connected to the main shaft 7, and the shell 3 is rotatably mounted on the main shaft 7; a plurality of piezoelectric substrates 20 are mounted on the main shaft 7, and the main extension surface of the piezoelectric substrate 20 is perpendicular to the main shaft 7, the root of the piezoelectric substrate 20 is connected to the main shaft 7, and the plurality of piezoelectric substrates 20 are equidistant and arranged radially with the axis of the main shaft 7 as the center, and the free Two fixed magnets 22 are installed on both sides of the end, and the two end faces of the inner side of the shell 3 are close to the piezoelectric matrix 20. A number of spaced moving magnets 21 are set on the inner end face of the shell 3, and multiple moving magnets 21 are arranged in a ring with the axis of the main shaft 7 as the rotation center. The polarities of two adjacent moving magnets are opposite, and the polarities of the fixed magnets 22 on the first side of the multiple piezoelectric matrix 20 are the same, and the polarity of the fixed magnets 22 on the second side of the piezoelectric matrix 20 is the same and opposite to the polarity of the fixed magnets 22 on the first side; the unidirectional drive mechanism is installed on the external fixed support 4, and can drive the shell 3 to rotate unidirectionally, so that the staggered moving magnetic poles in the shell 3 form a continuous sinusoidal excitation on the fixed magnets 22 on the piezoelectric matrix 20, so that the piezoelectric matrix 20 generates electricity.

[0034] The following describes this system in detail.

[0035] like Figure 1 As shown, the main shaft 7 of this system has spline structures at both ends. An external fixing arm 2 is also mounted on the side of the first fixing arm facing the main shaft 7. The external fixing arm 2 is L-shaped, and the end of the first fixing arm forms a U-shaped structure with the external fixing arm 2. The two ends of this U-shaped structure are fixedly connected to the main shaft 7 via spline structures. In this embodiment, the first fixing arm 1 and the external fixing arm 2 are connected to the main shaft 7, and their rotation is centered around the axis of the main shaft 7.

[0036] Both the first and second fixing arms 1, 5 are equipped with straps 6. These arms are curved to accommodate wear on the thigh and calf. The first arm 1 is secured to the thigh via the straps 6, while the second arm 5 is secured to the calf via the straps 6. These features conform to the curves of the leg and provide a comfortable fit.

[0037] Combine Figure 2 and Figure 5As shown, the diameter of the middle portion of the main shaft 7 is larger than the diameter of the main body of the main shaft 7, forming a cylindrical structure. The cylindrical structure is provided with multiple elongated mounting grooves 8, which extend annularly along the cylindrical structure. Slots 9 are provided on either side of each group of mounting grooves 8. The main body of the mounting grooves 8 extends axially along the cylindrical structure. The root of the piezoelectric substrate 20 is inserted into the mounting grooves 8. Baffles 19 are provided on both sides of the piezoelectric substrate 20, and the root of the baffles 19 is inserted into the slots 9. The piezoelectric substrate 20 and the two adjacent baffles 19 form a piezoelectric cantilever beam with an "H"-shaped cross-section.

[0038] The slot 9 is an "L"-shaped structure, and the bottom of the slot 9 extends vertically away from the mounting slot 8; one end of the slot 9 passes through the first end of the cylindrical structure; the piezoelectric matrix 20 has a mounting hole, and the end face of the first end of the cylindrical structure is provided with a mounting hole for fixing the root of the piezoelectric matrix 20.

[0039] The main shaft 7 has splined ends, and a non-through wire hole 11 is provided near the inner thigh side to collect the wires leading from the piezoelectric cantilever beam. The wire hole 11 is 45° away from the fixed position of the piezoelectric substrate 20, and is then connected to an external energy storage device. The main shaft 7 also has a wire hole 10 that communicates with the wire hole 11. The main shaft 7 has an uneven cross-section structure, with the middle section having the largest cross-section. It is equipped with a slot 9 for inserting the baffle, a mounting groove 8 for inserting the piezoelectric substrate 20, and a bolt hole for fixing the piezoelectric substrate 20.

[0040] like Figure 2 As shown, the largest cross-section of the main shaft 7 is provided with a baffle slot 9 and a bolt hole for securing the piezoelectric substrate 20. The main shaft 7 is connected to the fixed walls of the first fixed arm 1 and the outer fixed support arm 2 on both sides via spline structures at both ends. The entire main shaft 7 is located at the center of the device and can be considered as the fixed origin. It is responsible for fixing the piezoelectric cantilever beam and serving as the central axis of rotation for each bearing.

[0041] In this embodiment, taking the energy harvesting system installed at the knee joint as an example, the first fixed arm 1 is mounted on the thigh via a strap 6, and the second fixed arm 5 is mounted on the calf via a strap 6. With the main shaft 7 as the fixed axis, the housing 3 contains moving magnets 21 with the same polarity, arranged symmetrically about the plane containing the main shaft 7's axis. The moving magnets 21 partially exposed on the inner end surface of the housing 3 have the same polarity in the direction normal to the plane where they are exposed. Adjacent moving magnets 21 on either side of the mounting plane have opposite polarities. Correspondingly, on the piezoelectric cantilever beam, one side has the same polarity as the moving magnet 21 on the same side, while the other side has the opposite polarity. During the early stages of leg swing, the angle between the thigh and calf decreases, driving the pawl 13, which in turn drives the ratchet and housing 3 to rotate. This causes the staggered magnetic poles within the housing 3 to generate a continuous sinusoidal excitation on the cantilever beam. In the middle stage of human leg swing, the angle between the femur and the tibia increases, the ratchet 13 retreats, and slides into the ratchet tooth groove in sequence under the action of the tension spring 12.

[0042] The structure of the ratchet and pawl 13 is as follows: Figure 3 As shown, the pawl 13 is connected to the external fixed support 4, and an annular groove is provided on the pawl 13 to fix one end of the tension spring 12. A mounting hole is also provided on the external fixed support 4 to fix the other end of the tension spring 12. A groove matching the length and shape of the tension spring 12 is provided on the external fixed support 4 to prevent the friction resistance caused by the spring to the rotating housing 3 during travel.

[0043] like Figure 4 As shown, the external fixed support 4 also has a mounting plate for mounting the one-way drive mechanism. This mounting plate is rotatably connected to the main shaft 7 via a flange bearing 16. The inner side of the mounting plate faces the housing 3, and the one-way drive mechanism is mounted on the side of the one-way drive mechanism facing the housing 3. The housing 3 has a ratchet on the side facing the mounting plate, and the mounting plate has a pawl 13 on the side facing the ratchet. The tail of the pawl 13 is rotatably mounted on the mounting plate via a positioning shaft. The inner side of the mounting plate also has a tension spring 12, with its ends connected to the mounting plate and the front of the pawl 13, respectively, to ensure that the pawl 13 is always pressed against the teeth of the ratchet.

[0044] When the device is stimulated by the legs, the pawl 13 drives the ratchet to rotate, thereby driving the housing 3 and the moving magnet 21 inside the housing 3 to rotate. The moving magnet 21 rotates continuously, thereby generating a sinusoidal excitation on the moving magnet 21 of the piezoelectric cantilever on the main shaft 7. The piezoelectric cantilever on the main shaft 7 will generate vibrations in the same axial direction as the main shaft 7. The vibration of the piezoelectric substrate 20 causes the piezoelectric film to deform, thereby forming an electric potential difference between the upper and lower surfaces of the piezoelectric film, ultimately achieving the energy collection function under this excitation. To meet the needs of different application scenarios, the number of cantilever beams can be adjusted, or the number of rotating magnets can be adjusted. In addition, the structure in which the main shaft 7 is stationary and the housing rotates can also be applied to rotating structures such as automobile wheels.

[0045] like Figure 5 As shown, there are gaskets 17 and locking plates 18 on both sides of the cylindrical structure, respectively. The gaskets 17 and locking plates 18 are connected and positioned by screws passing through the hole interface at the tail of the piezoelectric substrate 20, the mounting holes on the cylindrical structure, and the gaskets 17 and locking plates 18.

[0046] The piezoelectric cantilever beam is inserted into the corresponding mounting slots 8 and slots 9 of the spindle 7. The piezoelectric cantilever beam has a trapezoidal structure, with the fixed end at the root of the piezoelectric cantilever beam as the long side and the free end as the short side. A fixed magnet 22 at the free end serves as the excitation object of the rotating magnet and the end mass. The fixed magnet 22, serving as the end mass of the cantilever beam, is connected to the piezoelectric substrate 20 via structural adhesive. Under the continuous excitation of the moving magnet 21, the fixed magnet 22 produces displacement along the plane normal of the piezoelectric substrate 20.

[0047] In one embodiment, the first end of the housing 3 is mounted on the main shaft 7 via a first bearing 23, and the second end of the housing 3 is mounted on the main shaft 7 via a third bearing 27. The distal end of the second fixed arm 5 has an annular structure, and the annular structure of the second fixed arm 5 is connected to the second end of the housing 3 via a second bearing 26. The upper end of the second fixed arm serves as a rotating arm rotatably connected to the main shaft 7. The second fixed arm also serves to mount an external fixed support 4, which serves as a mounting base for the one-way drive mechanism. In this embodiment, the one-way drive mechanism includes a tension spring 12 and a pawl 13, and a ratchet is fixedly connected to the housing 3 on the side of the housing 3 facing the one-way drive mechanism.

[0048] Combine Figure 1 、 Figure 4 and Figure 6As shown, the first fixed arm 1 is connected to the third bearing 27, the inner housing 15 is fitted on the outer ring of the third bearing 27, and the moving magnet 21 is inserted into the moving magnet 21 groove in the inner housing 15 and fixed with structural adhesive. Similarly, the outer housing 14 and the moving magnet 21 are fitted in the same manner as described above. The assembled main shaft 7 is inserted into the spline groove of the upper fixed arm through a spline structure. The outer ring of the first bearing 23 is fitted with the outer housing 14, and the inner ring of the first bearing 23 is fitted with the main shaft 7. The inner housing 15 is connected to the outer housing 14 by bolts and nuts. The ratchet on the outer end face of the outer housing 14 engages with the pawl 13, and the pawl 13 is provided with an annular groove for fixing the tension spring 12. Correspondingly, the outer fixed support 4 is also provided with a fixing hole for fixing the tension spring 12. The specific implementation is shown in FIG. Figure 3 The pawl 13 engages with the locating pin on the external fixed support 4. The locating pin is provided with a protrusion to prevent the pawl 13 from falling out or interfering with the movement of the housing 3. The external fixed support 4 is fixed to the lower fixed arm via bolts and nuts. A bushing 25 is provided in the gap between the external fixed support 4 and the outer housing 14. The flange bearing outer ring 24 of the flange bearing 16 engages with the outer side of the external fixed support 4. The spline groove on the external fixed support arm 2 mates with the spline on the main shaft 7 and is connected to the upper fixed arm via bolts and nuts.

[0049] In this embodiment, the specific structure of the piezoelectric cantilever beam is as follows: the first layer in the normal direction of the piezoelectric cantilever beam is paved with conductive glue, the area of ​​which is slightly smaller than or equal to the area of ​​the exposed section of the cantilever beam; the second layer is paved with a piezoelectric film (PVDF), the area of ​​which is slightly smaller than or equal to the area of ​​the above-mentioned first layer of conductive glue; a wire is inserted between the first and second layers as a positive (negative) lead; the third layer is paved with conductive glue, the area of ​​which is slightly smaller than or equal to the area of ​​the piezoelectric film; the fourth layer (outermost layer) is paved with conductive glue, the area of ​​which is smaller than the area of ​​the third layer of conductive glue; a wire is inserted between the third and fourth layers as a negative (positive) lead; the piezoelectric cantilever beams are arranged radially, and the magnets in the shell 3 are arranged in a ring lattice with the axis of the main shaft 7 as the center point, and their number can be adjusted according to the usage scenario.

[0050] The knee joint driven piezoelectric permanent magnet composite multi-vibrator energy harvesting system proposed in the present invention has stable and reliable operation and low processing, use and maintenance costs. It focuses on solving how to realize magnetically excited vibration energy harvesting when the human body walks.

[0051] The above content is only a preferred embodiment of the present invention. For ordinary technicians in this field, many changes can be made in the specific implementation methods and application scope based on the ideas of the present technical content. As long as these changes do not deviate from the concept of the present invention, they all fall within the scope of protection of this patent.

Claims

1. Knee joint driven piezoelectric permanent magnet composite multi-vibrator energy harvesting system, characterized by: It includes a first fixed arm, a shell, a second fixed arm, an external fixed support, a main shaft and a one-way driving mechanism, wherein the first fixed arm is connected to the main shaft, the external fixed support is connected to the end of the second fixed arm, the external fixed support is sleeved on the main shaft and rotatably connected to the main shaft, and the shell is rotatably mounted on the main shaft; A plurality of piezoelectric substrates are mounted on the spindle, and the main extension surface of the piezoelectric substrate is perpendicular to the spindle, the root of the piezoelectric substrate is connected to the spindle, and the plurality of piezoelectric substrates are equally spaced and radially arranged with the axis of the spindle as the center, two fixed magnets are mounted on both sides of the free end of each of the piezoelectric substrates, the two end faces at both ends of the inner side of the shell face close to the piezoelectric substrate, a plurality of spaced moving magnets are arranged on the inner end face of the shell, and the plurality of moving magnets are arranged in a ring with the axis of the spindle as the rotation center, the polarities of two adjacent moving magnets are opposite, and the polarities of the fixed magnets on the first side of the plurality of piezoelectric substrates are the same, and the polarities of the fixed magnets on the second side of the piezoelectric substrates are the same and opposite to the polarity of the fixed magnets on the first side; The unidirectional driving mechanism is installed on the external fixed support and can drive the shell to rotate unidirectionally, so that the moving magnetic poles arranged alternately in the shell form continuous sinusoidal excitation to the fixed magnets on the piezoelectric matrix, so that the piezoelectric matrix generates electricity.

2. The knee joint driven piezoelectric permanent magnet composite multi-vibrator energy collection system according to claim 1 is characterized in that: Both ends of the main shaft have a spline structure, and an external fixed arm is installed on the side of the first fixed arm facing the main shaft. The external fixed arm is an "L"-shaped structure, and the end of the first fixed arm forms a "U"-shaped structure with the external fixed arm. The two ends of the "U"-shaped structure are fixedly connected to the main shaft through a spline structure.

3. The knee joint driven piezoelectric permanent magnet composite multi-vibrator energy collection system according to claim 1 is characterized in that: The first end of the shell is sleeved on the main shaft through a first bearing, the second end of the shell is sleeved on the main shaft through a third bearing, the end of the second fixed arm has an annular structure, and the annular structure of the second fixed arm is connected to the shell through a second bearing.

4. The knee joint driven piezoelectric permanent magnet composite multi-vibrator energy collection system according to claim 1, characterized in that: The external fixed support also has a mounting plate for mounting the one-way drive mechanism, the mounting plate is rotatably connected to the main shaft through a flange bearing, the inner side of the mounting plate faces the housing, and the one-way drive mechanism is mounted on the one-way drive mechanism side facing the housing.

5. The knee joint driven piezoelectric permanent magnet composite multi-vibrator energy harvesting system according to claim 1 is characterized in that: The shell has a ratchet on the side facing the mounting plate, and the mounting plate has a pawl on the side facing the ratchet. The tail of the pawl is rotatably mounted on the mounting plate via a positioning shaft. The inner side of the mounting plate also has a tension spring, and both ends of the tension spring are respectively connected to the mounting plate and the front of the pawl so that the pawl is always pressed on the tooth structure of the ratchet.

6. The knee joint driven piezoelectric permanent magnet composite multi-vibrator energy harvesting system according to any one of claims 1 to 5, characterized in that: The diameter of the middle part of the main shaft is larger than the diameter of the main shaft body and forms a cylindrical structure, on which a plurality of long strip-shaped mounting grooves are provided, the mounting grooves extend in an annular manner along the cylindrical structure, and slots are provided on both sides of each group of mounting grooves, and the mounting groove body extends along the axial direction of the cylindrical structure; The root of the piezoelectric matrix is ​​inserted in the installation groove, and baffles are arranged on both sides of the piezoelectric matrix, and the root of the baffles is inserted in the slot.

7. The knee joint driven piezoelectric permanent magnet composite multi-vibrator energy collection system according to claim 6, characterized in that: The piezoelectric substrate and two baffles adjacent to the piezoelectric substrate form a piezoelectric cantilever beam with an "H"-shaped cross section.

8. The knee joint driven piezoelectric permanent magnet composite multi-vibrator energy collection system according to claim 6, characterized in that: The slot is an "L"-shaped structure, and the bottom of the slot extends vertically away from the mounting slot; one end of the slot passes through the first end of the cylindrical structure; the piezoelectric matrix has a hole structure, and a mounting hole for fixing the root of the piezoelectric matrix is ​​provided on the end face of the first end of the cylindrical structure, and the mounting hole passes through the cylindrical structure.

9. The knee joint driven piezoelectric permanent magnet composite multi-vibrator energy collection system according to claim 8, characterized in that: The two sides of the cylindrical structure are also provided with gaskets and locking plates respectively. The gaskets and locking plates are connected and positioned by screws penetrating the hole interface at the tail of the piezoelectric substrate, the mounting holes on the cylindrical structure, and the gaskets and locking plates.

10. The knee joint driven piezoelectric permanent magnet composite multi-vibrator energy collection system according to claim 1, characterized in that: The first fixing arm and the second fixing arm are both provided with straps; the first fixing arm and the second fixing arm are both bent to a certain extent so as to be worn on the thigh and calf of a human body; and the main shaft is also provided with threading holes.

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