Ultra-low frequency rotating high-efficiency energy collector below 2 Hz based on impact frequency doubling and its design method

Abstract

The present invention relates to an ultra-low frequency rotating high-efficiency energy collector below 2 Hz based on impact frequency doubling and a design method thereof. When a free excitation ball moves to both sides of the energy collector, the free excitation ball interacts with a secondary piezoelectric energy collecting piezoelectric material layer, and the secondary piezoelectric energy collecting substrate is squeezed and deformed in contact with a toggle contact, thereby realizing the conversion of kinetic energy into electrical energy and spring potential energy, and acting on the primary piezoelectric energy collecting piezoelectric material layer through a spring, thereby realizing energy conversion of the primary piezoelectric structure; when the energy collector continues to flip, the spring potential energy will push the free excitation ball in the form of mechanical force to obtain a higher reverse speed, and then enter the second half of the cycle to repeat the above process. The present invention realizes the reciprocating change excitation of the two-stage piezoelectric structure by the free excitation ball through a two-stage piezoelectric structure and a coil design, and collects energy in a rotating environment in the order of piezoelectric-electromagnetic-piezoelectric-electromagnetic within one cycle, which is suitable for low-frequency rotating environments and realizes energy supply to other structures such as sensor nodes.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy collection, and in particular relates to an ultra-low frequency rotating high-efficiency energy collector below 2 Hz based on impact frequency doubling and a design method thereof. Background Art

[0002] Sensors are an important means of obtaining information. Together with communications and computers, they are called the "three pillars of modern information technology" and involve all areas of national economy and national defense research. Sensor technology is developing in the direction of intelligence, miniaturization, low power consumption, and wireless. In the future, there will be tens of billions of wireless sensor devices and nodes that need to be powered. The operation and maintenance pressure and environmental pollution caused by traditional battery power supply have become bottlenecks for the application of related technologies.

[0003] Self-powered technology is an emerging technology that collects ineffective energy in the environment to power low-power devices. It has received widespread attention and research in the past decade. With the development of self-powered technology, the energy supply bottleneck of traditional wireless sensor systems is expected to achieve a revolutionary breakthrough and be upgraded to a self-sufficient, unmanned, and long-term self-sustaining "self-powered" system. At present, solar energy, thermal energy, radio frequency energy, and mechanical energy are the main energy sources for self-powered energy. Mechanical energy has the advantages of wide existence, rich energy conversion mechanisms, and easy miniaturization. Its research areas involve vehicles, natural environment, buildings, heartbeats, and limb activities. Mechanical energy harvesting has become one of the hot technologies in the field of self-powered energy.

[0004] In mechanical motion, vibration and rotation are representative forms of mechanical energy. Vibration is a reciprocating motion near the equilibrium position. Its energy collection is easy to achieve and has been developed earlier. As an important common technology, rotational self-powered energy is expected to achieve revolutionary breakthroughs in many fields. However, the direction of rotational linear velocity lacks reciprocating excitation, so its development is relatively slow. The methods of rotational energy collectors include the following:

[0005] Gravity piezoelectric type: The scheme uses the periodic changes in stress generated by the earth's gravity field as the excitation. The gravity type has a stable excitation source and does not require a fixed auxiliary structure, so it can be applied to independent closed structures. The important limitation of the gravity type is that the cantilever beam needs to reach a resonant state. Due to the thickness of the piezoelectric material, the inertia moment and stiffness of the piezoelectric beam are significantly improved compared to a single beam without piezoelectric material, and the design of an ultra-low resonant frequency of 0-2Hz is more difficult.

[0006] Piezoelectric: The scheme uses the contact piezoelectric action between the static piezoelectric structure and the protruding part of the rotating structure as the excitation. This mechanism can convert the excitation into high-frequency damped vibration, but the prying force under low-frequency excitation decreases significantly. The mechanical contact of the piezoelectric excitation type is not conducive to extending the life of the collection structure, especially when multiple excitation plectrums are used.

[0007] Magnetic piezoelectric: A scheme that uses the periodic magnetic force exerted on the magnet at the end of the piezoelectric beam as the excitation. It is divided into fixed beam-rotating magnet and fixed magnet-rotating beam schemes. Nonlinear magnetic force can be introduced to form a bistable potential well to further optimize performance. The magnetic excitation energy collector is a non-contact excitation method, which is beneficial to extend the life of the energy collector, but the nonlinear magnetic force requires precise design and has low efficiency under low-frequency conditions. Both magnetic excitation and toggle excitation require a fixed end to assist in generating relative displacement.

[0008] Electromagnetic: Based on the law of electromagnetic induction, the rotor magnet and the stator coil undergo relative displacement to complete the electromechanical conversion, usually operating at a high rotation frequency. The electromagnetic energy collector requires the magnet and the coil to produce a relatively high-speed relative motion, and also requires an external auxiliary fixed end.

[0009] Electrostatic type: Based on the principle of capacitor discharge, rotation causes relative movement between electrodes, resulting in changes in capacitance. Electrostatic rotary energy collectors are easy to combine with MEMS technology to achieve miniaturization and integration of energy collectors, and have good application prospects in wearable devices and other fields. Similarly, electrostatic energy collectors require the setting of stator and rotor structures, and the energy density is low under low-frequency conditions.

[0010] At present, the energy collection scheme under rotational excitation conditions has a key bottleneck problem of low energy collection efficiency in the low frequency band when it comes to practical applications. There are few studies on rotational motion in the frequency band below 2 Hz, and even fewer studies below 0.5 Hz. The collected energy density is usually around 10 μW / cm 3 the following. Summary of the invention

[0011] The purpose of the present invention is to overcome the shortcomings of the prior art and provide an ultra-low frequency rotating high-efficiency energy collector below 2 Hz based on impact frequency doubling and a design method thereof, which can realize efficient energy collection in a rotating environment, and is particularly suitable for an ultra-low frequency rotating environment with an excitation frequency of 0 to 2 Hz.

[0012] The present invention solves the technical problem by the following technical solutions:

[0013] A super low frequency rotating high efficiency energy collector below 2 Hz based on impact frequency doubling, characterized in that it comprises a turntable, a shell, a primary piezoelectric energy collecting substrate, a primary piezoelectric energy collecting piezoelectric material layer, a spring, a secondary piezoelectric energy collecting substrate, a secondary piezoelectric energy collecting piezoelectric material layer, an electromagnetic energy collecting coil and a free excitation ball; the shell is coaxially fixedly installed on the turntable, the primary piezoelectric energy collecting substrate is symmetrically installed at both ends of the shell, the primary piezoelectric energy collecting piezoelectric material layer is bonded to the outside of the primary piezoelectric energy collecting substrate, the outer side of the primary piezoelectric energy collecting piezoelectric material layer is connected to the secondary piezoelectric energy collecting substrate through a spring, the secondary piezoelectric energy collecting piezoelectric material layer is connected to the secondary piezoelectric energy collecting substrate, fixed wave contacts are arranged at both ends of the shell on one side of the secondary piezoelectric energy collecting substrate, and the inner wall side of the shell An electromagnetic energy collecting coil is arranged on the shell, and the electromagnetic energy collecting coil covers the whole length of the shell, and a free excitation ball is built in the shell; when the energy collector rotates, the free excitation ball is subjected to the acceleration of gravity and reciprocates in the shell, and generates electrical energy by relative displacement with the electromagnetic energy collecting coil. When the free excitation ball moves to both sides of the energy collector, the free excitation ball interacts with the secondary piezoelectric energy collecting piezoelectric material layer, and the secondary piezoelectric energy collecting substrate is squeezed and contacts with the toggle contact to produce deformation, thereby realizing the conversion of kinetic energy into electrical energy and spring potential energy, and acts on the primary piezoelectric energy collecting piezoelectric material layer through the spring to realize the primary piezoelectric structure energy conversion; when the energy collector continues to flip, the spring potential energy will push the free excitation ball in the form of mechanical force to obtain a higher reverse speed, and then enter the second half cycle to repeat the above process.

[0014] Moreover, the turntable is of any rotatable structure, the rotation axis of the turntable is parallel to the ground, and the turntable plane is perpendicular to the ground.

[0015] Moreover, the shell is cylindrical or cubic.

[0016] Moreover, the primary piezoelectric energy collecting substrate is a metal curved structure, which is rectangular or cymbal-shaped, and both sides of the primary piezoelectric energy collecting substrate are connected to the edge of the shell; the secondary piezoelectric energy collecting substrate is a metal planar structure, which is rectangular or circular.

[0017] Moreover, the primary piezoelectric energy collecting piezoelectric material layer is PZT or PVDF, and its area is slightly smaller than the primary piezoelectric energy collecting substrate; the secondary piezoelectric energy collecting piezoelectric material layer is PZT or PVDF, and its area is slightly smaller than the secondary piezoelectric energy collecting substrate.

[0018] Moreover, the fixed toggle contact is a triangular elastic material, such as ABS, and its height is slightly larger than the width of the shell minus the length of the secondary piezoelectric energy collecting substrate, and overlaps with the secondary piezoelectric energy collecting substrate.

[0019] Moreover, the free excitation ball is a small magnetic ball, and its diameter is slightly smaller than the minimum side length of the shell.

[0020] Moreover, the motion process of the energy collector in one cycle is:

[0021] (1) When the energy collector is oriented vertically, the free excitation ball in the shell moves toward the bottom of the shell under the action of gravity, and the free excitation ball passes through the electromagnetic energy collection coil to generate electricity;

[0022] (2) When the energy collector rotates 90° clockwise, during this rotation process, the free excitation ball in the shell collides with the secondary piezoelectric energy collector substrate, the secondary piezoelectric energy collector piezoelectric material layer, the primary piezoelectric energy collector substrate, and the primary piezoelectric energy collector piezoelectric material layer at the bottom under the action of gravity and centrifugal force, and the energy collector generates electrical energy through the piezoelectric effect;

[0023] (3) When the energy collector rotates 180° clockwise, the free excitation ball in the shell begins to move from one side of the shell to the other side under the action of gravity, and during the movement, it still passes through the electromagnetic energy collection coil to generate electricity;

[0024] (4) When the energy collector rotates 270° clockwise, during this rotation process, the free excitation ball in the shell collides with the secondary piezoelectric energy collecting substrate, the secondary piezoelectric energy collecting piezoelectric material layer, the primary piezoelectric energy collecting substrate, and the primary piezoelectric energy collecting piezoelectric material layer again under the action of gravity, and the free excitation ball is located at the bottom of the shell again, and the energy collector still generates electrical energy through the piezoelectric effect;

[0025] (5) When the energy collector rotates 360°, it returns to its initial state, and the free excitation ball returns to the bottom of the shell under the action of gravity to complete a cycle of motion.

[0026] A design method for an ultra-low frequency rotating high-efficiency energy collector below 2 Hz based on impact frequency doubling, characterized in that the method comprises the following steps:

[0027] (1) Determine the dimensions of the shell, electromagnetic energy collection coil, and free excitation ball

[0028] Assume that the length of the shell is L and the width or diameter is D. Under this size, the free excitation ball should meet the condition of being able to hit the piezoelectric structures at both ends. The force on the free excitation ball at any time is:

[0029] F=Mgsinwt-μMgcoswt-Mw 2 e

[0030] Where: M is the mass of the free excitation ball, w is the rotational angular velocity of the energy collector, μ is the sliding friction coefficient of the inner wall of the shell, e is the axial distance between the free excitation ball and the rotation center of the shell, and g is the gravitational acceleration;

[0031] Considering that the friction force component can be controlled to a smaller level by grinding the inner wall of the shell, and the centrifugal force component is significantly smaller than gravity due to the small moving distance and rotation frequency, the force condition of the free excitation ball at any time can be simplified as:

[0032] F=Mgsinwt

[0033] The excitation ball is The axial movement distance in time is:

[0034]

[0035] The condition for the excitation ball to hit the piezoelectric structures at both ends is that the maximum axial movement distance of the excitation ball within a half cycle is greater than the length L of the shell, that is, it satisfies:

[0036]

[0037] Considering the application environment is a low-frequency rotation environment of 0 to 2 Hz, the shell length L should satisfy L ≤ 20 cm, the shell length L is taken as 15 cm, and the shell width or diameter D is 25 mm; considering the thickness of the shell and the gap between the free excitation ball and the shell, the diameter d of the excitation ball is set b The coil needs to cover the entire shell, so the coil wire diameter is 0.2mm, the diameter is 25mm, the length is 15cm, and the number of turns is 1500.

[0038] (2) Determine the size of the spring

[0039] Assume the spring wire diameter is d t , the spring diameter is D t , the effective number of spring coils is n, the shear modulus of the spring material is G, then the spring constant k t for:

[0040]

[0041] When the spring stiffness is equal to the stiffness of the piezoelectric energy collecting piezoelectric material layer, the piezoelectric structure can obtain a relatively large output voltage. When the piezoelectric energy collecting piezoelectric material layer structure is a disc structure, the stiffness of the piezoelectric disc is:

[0042]

[0043] Where, E represents the elastic modulus of the piezoelectric disk, h represents the thickness of the piezoelectric disk, and d f represents the diameter of the piezoelectric disk;

[0044] Therefore, the effective number of coils n of the spring can be determined by the following formula:

[0045]

[0046] Considering practical applications, the spring wire diameter is set to 0.5mm and the spring middle diameter is set to 10mm;

[0047] (3) Determine the dimensions of the primary piezoelectric energy collecting substrate, the primary piezoelectric energy collecting piezoelectric material layer, the secondary piezoelectric energy collecting substrate, and the secondary piezoelectric energy collecting piezoelectric material layer

[0048] The size of the primary piezoelectric energy collecting substrate and the primary piezoelectric energy collecting piezoelectric material layer is slightly larger than the shell width or diameter D, which is designed to be 28 mm in the present invention, and is fixedly connected to both sides after being bent, and the primary piezoelectric energy collecting substrate and the primary piezoelectric energy collecting piezoelectric material layer are connected by epoxy resin glue; the size of the secondary piezoelectric energy collecting substrate and the secondary piezoelectric energy collecting piezoelectric material layer is slightly smaller than the shell width or diameter D, which is designed to be 20 mm in the present invention, and there is no fixed requirement for the thickness of the above structure;

[0049] (4) Determine the size of the fixed toggle contact

[0050] The contact is an equilateral triangle, and its height is slightly larger than the shell width or diameter D minus the size of the secondary piezoelectric energy collecting piezoelectric material layer, which is 25mm-20mm=5mm in the present invention, and the contact height is designed to be 7mm.

[0051] The advantages and beneficial effects of the present invention are:

[0052] The present invention is an ultra-low frequency rotating high-efficiency energy collector below 2 Hz based on impact frequency doubling and a design method thereof. The structural design is ingenious. Through the design of a two-stage piezoelectric structure and a coil, the reciprocating excitation of the two-stage piezoelectric structure by a free excitation ball is realized, and the energy in the rotating environment is collected in the order of piezoelectric-electromagnetic-piezoelectric-electromagnetic within one cycle. It is particularly suitable for low-frequency rotating environments and can realize energy supply to other structures such as sensor nodes. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figure 1 It is a schematic diagram of the structure of the present invention;

[0054] Figure 2 is a diagram of energy harvesting tested by the present invention;

[0055] Figure 3 It is the energy density diagram of the present invention after testing.

[0056] Description of Reference Numerals

[0057] 1-turntable, 2-shell, 3-and piezoelectric energy collecting substrate, 4-and piezoelectric energy collecting piezoelectric material layer, 5-spring, 6-secondary piezoelectric energy collecting substrate, 7-secondary piezoelectric energy collecting piezoelectric material layer, 8-fixed wave contact, 9-electromagnetic energy collecting coil, 10-free excitation ball. DETAILED DESCRIPTION

[0058] The present invention is further described in detail below through specific examples. The following examples are only illustrative and not restrictive, and the protection scope of the present invention cannot be limited thereto.

[0059] like Figure 1 As shown, an ultra-low frequency rotating high-efficiency energy collector below 2 Hz based on impact frequency doubling is characterized in that it includes a turntable 1, a shell 2, a primary piezoelectric energy collecting substrate 3, a primary piezoelectric energy collecting piezoelectric material layer 4, a spring 5, a secondary piezoelectric energy collecting substrate 6, a secondary piezoelectric energy collecting piezoelectric material layer 7, an electromagnetic energy collecting coil 9 and a free excitation ball 10; the shell 2 is coaxially fixedly installed on the turntable 1, and the primary piezoelectric energy collecting substrate 3 is symmetrically installed at both ends of the shell 2, the primary piezoelectric energy collecting substrate 3 is bonded to the outside of the primary piezoelectric energy collecting substrate 3, the outer side of the primary piezoelectric energy collecting piezoelectric material layer 4 is connected to the secondary piezoelectric energy collecting substrate 6 through a spring 5, the secondary piezoelectric energy collecting substrate 6 is connected to the secondary piezoelectric energy collecting piezoelectric material layer 7, and fixed wave contacts 8 are provided at both ends of the shell on one side of the secondary piezoelectric energy collecting substrate 6. An electromagnetic energy collecting coil 9 is arranged on the side of the inner wall of the shell 2, and the electromagnetic energy collecting coil 9 covers the entire length of the shell 2. A free excitation ball 10 is built into the shell 2; when the energy collector rotates, the free excitation ball is subjected to the acceleration of gravity and reciprocates in the shell, and generates electrical energy by relative displacement with the electromagnetic energy collecting coil. When the free excitation ball moves to both sides of the energy collector, the free excitation ball interacts with the secondary pressure point energy collecting piezoelectric material layer, and the secondary piezoelectric energy collecting substrate is squeezed and contacts with the toggle contact to produce deformation, thereby realizing the conversion of kinetic energy into electrical energy and spring potential energy, and acting on the primary piezoelectric energy collecting piezoelectric material layer through the spring to realize the primary piezoelectric structure energy conversion; when the energy collector continues to flip, the spring potential energy will push the free excitation ball in the form of mechanical force to obtain a higher reverse speed, and then enter the second half cycle to repeat the above process.

[0060] The turntable 1 is a rotatable arbitrary structure, the rotation axis of the turntable 1 is parallel to the ground, and the plane of the turntable 1 is perpendicular to the ground. The housing 2 is cylindrical or cubic.

[0061] The primary piezoelectric energy collecting substrate 3 is a metal curved structure, in the shape of a rectangle or a cymbal, and both sides of the primary piezoelectric energy collecting substrate 3 are connected to the edge of the shell 2; the secondary piezoelectric energy collecting substrate 6 is a metal planar structure, in the shape of a rectangle or a circle.

[0062] The primary piezoelectric energy collecting piezoelectric material layer 4 is PZT or PVDF, and its area is slightly smaller than the primary piezoelectric energy collecting substrate 3 ; the secondary piezoelectric energy collecting piezoelectric material layer 7 is PZT or PVDF, and its area is slightly smaller than the secondary piezoelectric energy collecting substrate 6 .

[0063] The fixed toggle contact 8 is made of triangular elastic material, such as ABS, and its height is slightly greater than the width of the shell minus the length of the secondary piezoelectric energy collecting substrate 6 , and overlaps with the secondary piezoelectric energy collecting substrate 6 .

[0064] The free excitation ball 10 is a small magnetic ball, and its diameter is slightly smaller than the minimum side length of the housing 2 .

[0065] The motion process of the energy collector in one cycle is:

[0066] (1) When the energy collector is oriented vertically, the free excitation ball in the shell moves toward the bottom of the shell under the action of gravity, and the free excitation ball passes through the electromagnetic energy collection coil to generate electricity;

[0067] (2) When the energy collector rotates 90° clockwise, during this rotation process, the free excitation ball in the shell collides with the secondary piezoelectric energy collector substrate, the secondary piezoelectric energy collector piezoelectric material layer, the primary piezoelectric energy collector substrate, and the primary piezoelectric energy collector piezoelectric material layer at the bottom under the action of gravity and centrifugal force, and the energy collector generates electrical energy through the piezoelectric effect;

[0068] (3) When the energy collector rotates 180° clockwise, the free excitation ball in the shell begins to move from one side of the shell to the other side under the action of gravity, and during the movement, it still passes through the electromagnetic energy collection coil to generate electricity;

[0069] (4) When the energy collector rotates 270° clockwise, during this rotation process, the free excitation ball in the shell collides with the secondary piezoelectric energy collecting substrate, the secondary piezoelectric energy collecting piezoelectric material layer, the primary piezoelectric energy collecting substrate, and the primary piezoelectric energy collecting piezoelectric material layer again under the action of gravity, and the free excitation ball is located at the bottom of the shell again, and the energy collector still generates electrical energy through the piezoelectric effect;

[0070] (5) When the energy collector rotates 360°, it returns to its initial state, and the free excitation ball returns to the bottom of the shell under the action of gravity to complete a cycle of motion.

[0071] A design method for an ultra-low frequency rotating high-efficiency energy collector below 2 Hz based on impact frequency doubling, characterized in that the method comprises the following steps:

[0072] (1) Determine the dimensions of the shell, electromagnetic energy collection coil, and free excitation ball

[0073] Assume that the length of the shell is L and the width or diameter is D. Under this size, the free excitation ball should meet the condition of being able to hit the piezoelectric structures at both ends. The force on the free excitation ball at any time is:

[0074] F=Mgsinwt-μMgcoswt-Mw 2 e

[0075] Where: M is the mass of the free excitation ball, w is the rotational angular velocity of the energy collector, μ is the sliding friction coefficient of the inner wall of the shell, e is the axial distance between the free excitation ball and the rotation center of the shell, and g is the gravitational acceleration;

[0076] Considering that the friction force component can be controlled to a smaller level by grinding the inner wall of the shell, and the centrifugal force component is significantly smaller than gravity due to the small moving distance and rotation frequency, the force condition of the free excitation ball at any time can be simplified as:

[0077] F=Mgsinwt

[0078] The excitation ball is The axial movement distance in time is:

[0079]

[0080] The condition for the excitation ball to hit the piezoelectric structures at both ends is that the maximum axial movement distance of the excitation ball within a half cycle is greater than the length L of the shell, that is, it satisfies:

[0081]

[0082] Considering the application environment is a low-frequency rotation environment of 0 to 2 Hz, the shell length L should satisfy L ≤ 20 cm, the shell length L is taken as 15 cm, and the shell width or diameter D is 25 mm; considering the thickness of the shell and the gap between the free excitation ball and the shell, the diameter d of the excitation ball is set b The coil needs to cover the entire shell, so the coil wire diameter is 0.2mm, the diameter is 25mm, the length is 15cm, and the number of turns is 1500.

[0083] (2) Determine the size of the spring

[0084] Assume the spring wire diameter is d t , the spring diameter is D t , the effective number of spring coils is n, the shear modulus of the spring material is G, then the spring constant k t for:

[0085]

[0086] When the spring stiffness is equal to the stiffness of the piezoelectric energy collecting piezoelectric material layer, the piezoelectric structure can obtain a relatively large output voltage. When the structure of the piezoelectric energy collecting piezoelectric material layer is a disc structure, the stiffness of the piezoelectric disc is:

[0087]

[0088] Where, E represents the elastic modulus of the piezoelectric disk, h represents the thickness of the piezoelectric disk, and d frepresents the diameter of the piezoelectric disk;

[0089] Therefore, the effective number of coils n of the spring can be determined by the following formula:

[0090]

[0091] Considering practical applications, the spring wire diameter is set to 0.5mm and the spring middle diameter is set to 10mm;

[0092] (3) Determine the dimensions of the primary piezoelectric energy collecting substrate, the primary piezoelectric energy collecting piezoelectric material layer, the secondary piezoelectric energy collecting substrate, and the secondary piezoelectric energy collecting piezoelectric material layer

[0093] The size of the primary piezoelectric energy collecting substrate and the primary piezoelectric energy collecting piezoelectric material layer is slightly larger than the shell width or diameter D, which is designed to be 28 mm in the present invention, and is fixedly connected to both sides after being bent, and the primary piezoelectric energy collecting substrate and the primary piezoelectric energy collecting piezoelectric material layer are connected by epoxy resin glue; the size of the secondary piezoelectric energy collecting substrate and the secondary piezoelectric energy collecting piezoelectric material layer is slightly smaller than the shell width or diameter D, which is designed to be 20 mm in the present invention, and there is no fixed requirement for the thickness of the above structure;

[0094] (4) Determine the size of the fixed toggle contact

[0095] The contact is an equilateral triangle, and its height is slightly larger than the shell width or diameter D minus the size of the secondary piezoelectric energy collecting piezoelectric material layer, which is 25mm-20mm=5mm in the present invention, and the contact height is designed to be 7mm.

[0096] like Figure 2 As shown, when the rotation frequency is 10-60r / min, for a single secondary piezoelectric energy collecting piezoelectric material layer, 1, 2, 2, 3, 4, and 5 collisions will occur in sequence, and the electromagnetic energy collecting part will have 2, 4, 5, 6, 8, and 10 voltage peaks in sequence.

[0097] like Figure 3 As shown in the figure, it can be seen that the energy collection density of the high-efficiency energy collector designed by the present invention is more than 10μW / cm below 0.5Hz 3 , and the energy density increases with the increase of rotation frequency, so efficient energy collection in the 0-2Hz frequency band can be achieved.

[0098] Although the embodiments and drawings of the present invention are disclosed for illustrative purposes, those skilled in the art will appreciate that various substitutions, changes and modifications are possible without departing from the spirit and scope of the present invention and the appended claims. Therefore, the scope of the present invention is not limited to the contents disclosed in the embodiments and drawings.

Claims

1. An ultra-low frequency rotating high-efficiency energy collector below 2 Hz based on impact frequency doubling, characterized in that: The invention comprises a rotating disk (1), a shell (2), a primary piezoelectric energy collecting substrate (3), a primary piezoelectric energy collecting piezoelectric material layer (4), a spring (5), a secondary piezoelectric energy collecting substrate (6), a secondary piezoelectric energy collecting piezoelectric material layer (7), an electromagnetic energy collecting coil (9) and a free excitation ball (10); the shell (2) is coaxially fixedly mounted on the rotating disk (1), the primary piezoelectric energy collecting substrate (3) is symmetrically mounted at both ends of the shell (2), the primary piezoelectric energy collecting piezoelectric material layer (4) is bonded to the outside of the primary piezoelectric energy collecting substrate (3), the outer side of the primary piezoelectric energy collecting piezoelectric material layer (4) is connected to the secondary piezoelectric energy collecting substrate (6) through a spring (5), the secondary piezoelectric energy collecting substrate (6) is connected to the secondary piezoelectric energy collecting piezoelectric material layer (7), and fixed toggle contacts (8) are arranged at both ends of the shell on one side of the secondary piezoelectric energy collecting substrate (6). An electromagnetic energy collecting coil (9) is arranged on the side surface of the inner wall of the shell (2), and the electromagnetic energy collecting coil (9) covers the entire length of the shell (2). A free excitation ball (10) is built into the shell (2); when the energy collector rotates, the free excitation ball is subjected to the acceleration of gravity and reciprocates in the shell, and generates electrical energy by relative displacement with the electromagnetic energy collecting coil. When the free excitation ball moves to both sides of the energy collector, the free excitation ball interacts with the secondary piezoelectric energy collecting piezoelectric material layer, and the secondary piezoelectric energy collecting substrate is squeezed and contacts with the toggle contact to generate deformation, thereby realizing the conversion of kinetic energy into electrical energy and spring potential energy, and acting on the primary piezoelectric energy collecting piezoelectric material layer through the spring, thereby realizing the primary piezoelectric structure energy conversion; when the energy collector continues to flip, the spring potential energy will push the free excitation ball in the form of mechanical force to obtain a higher speed, and then enter the second half cycle to repeat the above process.

2. According to claim 1, the ultra-low frequency rotating high-efficiency energy collector below 2 Hz based on impact frequency doubling is characterized in that: The turntable (1) is of any rotatable structure, the rotation axis of the turntable (1) is parallel to the ground, and the plane of the turntable (1) is perpendicular to the ground.

3. According to claim 1, the ultra-low frequency rotating high-efficiency energy collector below 2 Hz based on impact frequency doubling is characterized in that: The shell (2) is cylindrical or cubic.

4. According to claim 1, the ultra-low frequency rotating high-efficiency energy collector below 2 Hz based on impact frequency doubling is characterized in that: The primary piezoelectric energy collecting substrate (3) is a metal curved structure, in the shape of a rectangle or a cymbal, and both sides of the primary piezoelectric energy collecting substrate (3) are connected to the edges of the shell (2); the secondary piezoelectric energy collecting substrate (6) is a metal flat structure, in the shape of a rectangle or a circle.

5. According to claim 1, the ultra-low frequency rotating high-efficiency energy collector below 2 Hz based on impact frequency doubling is characterized in that: The primary piezoelectric energy collecting piezoelectric material layer (4) is PZT or PVDF, and its area is smaller than the primary piezoelectric energy collecting substrate (3); the secondary piezoelectric energy collecting piezoelectric material layer (7) is PZT or PVDF, and its area is smaller than the secondary piezoelectric energy collecting substrate (6).

6. According to claim 1, the ultra-low frequency rotating high-efficiency energy collector below 2 Hz based on impact frequency doubling is characterized in that: The fixed toggle contact (8) is a triangular elastic material ABS, the height of which is greater than the width of the shell minus the length of the secondary piezoelectric energy collecting substrate (6), and overlaps with the secondary piezoelectric energy collecting substrate (6).

7. According to claim 1, the ultra-low frequency rotating high-efficiency energy collector below 2 Hz based on impact frequency doubling is characterized in that: The free excitation ball (10) is a small magnetic ball, the diameter of which is smaller than the minimum side length of the shell (2).

8. According to claim 1, the ultra-low frequency rotating high-efficiency energy collector below 2 Hz based on impact frequency doubling is characterized in that: The motion process of the energy collector in one cycle is: (1) When the energy collector is oriented vertically, the free excitation ball in the shell moves toward the bottom of the shell under the action of gravity, and the free excitation ball passes through the electromagnetic energy collection coil to generate electricity; (2) When the energy collector rotates 90° clockwise, during this rotation process, the free excitation ball in the shell collides with the secondary piezoelectric energy collector substrate, the secondary piezoelectric energy collector piezoelectric material layer, the primary piezoelectric energy collector substrate, and the primary piezoelectric energy collector piezoelectric material layer at the bottom under the action of gravity and centrifugal force, and the energy collector generates electrical energy through the piezoelectric effect; (3) When the energy collector rotates 180° clockwise, the free excitation ball in the shell begins to move from one side of the shell to the other side under the action of gravity, and during the movement, it still passes through the electromagnetic energy collection coil to generate electricity; (4) When the energy collector rotates 270° clockwise, during this rotation process, the free excitation ball in the shell collides with the secondary piezoelectric energy collecting substrate, the secondary piezoelectric energy collecting piezoelectric material layer, the primary piezoelectric energy collecting substrate, and the primary piezoelectric energy collecting piezoelectric material layer again under the action of gravity, and the free excitation ball is located at the bottom of the shell again, and the energy collector still generates electrical energy through the piezoelectric effect; (5) When the energy collector rotates 360°, it returns to its initial state, and the free excitation ball returns to the bottom of the shell under the action of gravity, completing a cycle of motion.

9. The design method of a 2 Hz ultra-low frequency rotating high-efficiency energy collector based on impact frequency doubling according to any one of claims 1 to 8, characterized in that: The method comprises the following steps: (1) Determine the dimensions of the shell, electromagnetic energy collection coil, and free excitation ball Assume that the length of the shell is L and the width or diameter is D. Under this size, the free excitation ball should meet the condition of being able to hit the piezoelectric structures at both ends. The force on the free excitation ball at any time is: F=Mgsinwt-μMgcoswt-Mw 2 a Where: M is the mass of the free excitation ball, w is the rotational angular velocity of the energy collector, μ is the sliding friction coefficient of the inner wall of the shell, e is the axial distance between the free excitation ball and the rotation center of the shell, and g is the gravitational acceleration; Considering that the friction force component can be controlled to a smaller level by grinding the inner wall of the shell, and the centrifugal force component is significantly smaller than gravity due to the small moving distance and rotation frequency, the force condition of the free excitation ball at any time can be simplified as: F=Mgsinwt The excitation ball is The axial movement distance in time is: The condition for the excitation ball to hit the piezoelectric structures at both ends is that the maximum axial movement distance of the excitation ball within a half cycle is greater than the length L of the shell, that is, it satisfies: Considering the application environment is a low-frequency rotation environment of 0 to 2 Hz, the shell length L should satisfy L ≤ 20 cm, the shell length L is taken as 15 cm, and the shell width or diameter D is 25 mm; considering the thickness of the shell and the gap between the free excitation ball and the shell, the diameter d of the excitation ball is set b The coil needs to cover the entire shell, so the coil wire diameter is 0.2mm, the diameter is 25mm, the length is 15cm, and the number of turns is 1500. (2) Determine the size of the spring Assume the spring wire diameter is d t , the spring diameter is D t , the effective number of spring coils is n, the shear modulus of the spring material is G, then the spring constant k t for: When the spring stiffness is equal to the stiffness of the piezoelectric energy collecting piezoelectric material layer, the piezoelectric structure can obtain a relatively large output voltage. When the piezoelectric energy collecting piezoelectric material layer structure is a disc structure, the stiffness of the piezoelectric disc is: Where, E represents the elastic modulus of the piezoelectric disk, h represents the thickness of the piezoelectric disk, and d f represents the diameter of the piezoelectric disk; Therefore, the effective number of coils n of the spring can be determined by the following formula: Considering practical applications, the spring wire diameter is set to 0.5mm and the spring middle diameter is set to 10mm; (3) Design the dimensions of the primary piezoelectric energy collecting substrate, the primary piezoelectric energy collecting piezoelectric material layer, the secondary piezoelectric energy collecting substrate, and the secondary piezoelectric energy collecting piezoelectric material layer The size of the primary piezoelectric energy collecting substrate and the primary piezoelectric energy collecting piezoelectric material layer is 28 mm, and they are bent and fixedly connected to both sides, and the primary piezoelectric energy collecting substrate and the primary piezoelectric energy collecting piezoelectric material layer are connected by epoxy resin glue; the size of the secondary piezoelectric energy collecting substrate and the secondary piezoelectric energy collecting piezoelectric material layer is 20 mm, and there is no fixed requirement for the thickness of the above structure; (4) Design fixed toggle contact size The contacts are equilateral triangles, the contact height is designed to be 7mm, and the shell width or diameter is 25mm.

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