CN107786122B - Collision frequency-increasing type piezoelectric energy harvester for collecting human body swing energy and energy harvesting method thereof - Google Patents

Abstract

The invention discloses a collision upconversion piezoelectric energy capture device that collects human body swing energy and an energy capture method thereof. The frequency of human movement is low, and it is difficult for existing piezoelectric energy harvesting devices to be in the effective energy harvesting frequency band, resulting in low output power. The circular shell base of the present invention includes a circular shell and a circular base; the rotating shaft and the circular base form a rotating pair; the pendulum weight is fixed on the rotating shaft, and a circular hole is opened at both ends of the plane of the pendulum weight. A magnet is embedded in the hole; n piezoelectric beams are evenly distributed on the rotating shaft along the circumferential direction; n pieces of paddles evenly distributed along the circumferential direction are fixed on the inner wall of the annular shell; two bosses are fixed on the inner wall of the annular shell. A magnet is fixed on the opposite surface of the boss and the pendulum weight plane. The pendulum weight of the present invention swings around the rotating axis at the human body swing frequency, thereby driving the piezoelectric beam to collide with the paddle through the rotating axis, causing the piezoelectric beam to vibrate at high frequency to generate electrical energy, realize up-frequency conversion, and introduce nonlinear stiffness through the magnet. Broaden the energy band.

Description

Collision-upconverter piezoelectric energy harvesting device that collects human body swing energy and its energy harvesting method

Technical field

The present invention relates to an energy collection device and an energy collection method, and in particular to a collision upconversion piezoelectric energy capture device that collects human body swing energy and an energy capture method thereof.

Background technique

There is a large amount of motion energy during human movement, such as the swing of arms and legs. Vibration energy harvesters can convert these swing forms of motion energy into electrical energy to power wearable electronics. In order not to affect the normal movement of the human body, this type of energy capture device is best to use the inertia of the mass block to capture the motion energy of the human body, rather than actively applying driving force manually. Piezoelectric materials can achieve high energy conversion efficiency due to their high electromechanical coupling coefficient. Therefore, they are widely used in vibration energy collection. However, due to the low frequency of human body movement, it is difficult for existing piezoelectric energy harvesting devices to be in the effective energy harvesting frequency band, resulting in low output power.

Contents of the invention

The purpose of the present invention is to propose a high-efficiency, high-output collision-upconversion piezoelectric energy capture device and its energy capture method in view of the problems of low output power and low efficiency of piezoelectric energy capture devices in low-frequency environments.

The technical solutions adopted by the present invention to solve the technical problems are:

The invention is a collision upconversion piezoelectric energy capture device that collects human body swing energy. It is composed of a paddle, a piezoelectric beam, a pendulum, a rotating shaft, a magnet, a circular shell base and a boss; the circular shell base includes an integrated A formed annular shell and a circular base; the rotating shaft and the circular base are coaxially arranged, and the rotating shaft and the circular base form a rotating pair. The pendulum weight includes a first semi-cylinder and a second semi-cylinder formed in one piece. The radius of the first semi-cylinder is 2 to 4 mm larger than the radius of the rotating shaft. The radius of the second semi-cylinder is 4 to 6 mm smaller than the inner diameter of the annular shell. ; Half of the central hole opened by the pendulum weight is located on the first semi-cylinder, and the other half is located on the second semi-cylinder; the center hole of the pendulum weight is fixed on the rotating shaft, and a circular hole is opened at both ends of the plane of the second semi-cylinder. , a magnet is embedded in each circular hole. n piezoelectric beams are evenly distributed on the rotating shaft along the circumferential direction of the rotating shaft, 4≤n≤8. n pieces of picks evenly distributed along the circumferential direction are fixed on the inner wall of the annular shell; in the axial direction of the rotating shaft, the picks are aligned with the piezoelectric beam; in the radial direction of the rotating shaft, the distance between the picks and the axis of the rotating shaft is smaller than the outer end of the piezoelectric beam The distance between the end face and the axis of the rotating shaft; two bosses are fixed on the inner wall of the annular shell, and the two bosses are located at both ends of the plane of the second semi-cylinder, and the distance between the central axis of the rotating shaft and the two bosses is equal; In the axial direction of the rotating shaft, the distance between the boss and the piezoelectric beam is set; a magnet is fixed on the opposite surface of the boss and the second semi-cylinder plane. When the plane of the second half-cylinder is parallel to the plane of the fixed magnet on the boss, the magnet on the second half-cylinder is coaxially arranged with the magnet on the boss at the corresponding end and the magnetic poles at the opposite ends are the same.

The annular shell is provided with an adjustment hole group near the two bosses; the adjustment hole group includes three adjustment holes arranged along the circumference of the annular shell, and the center of each two adjustment holes The angles between the axes are equal; the boss is connected to one of the adjustment holes through screws.

The magnet adopts a cylinder.

The energy harvesting method of the collision upconversion piezoelectric energy harvester that collects human body swing energy is as follows:

When carrying, the pendulum weight is placed horizontally. The pendulum weight swings around the rotating axis at the frequency of human body swing, thereby driving the piezoelectric beam to collide with the paddle through the rotating axis, causing the piezoelectric beam to vibrate at high frequency to generate electrical energy. When the pendulum weight swings, the magnets at both ends of the second semi-cylinder and the magnets on the corresponding end bosses mutually repel magnetic forces, which introduces nonlinear stiffness to the pendulum weight and broadens the effective energy capture band of the pendulum weight. When the human body swings at a frequency of When the effective energy capture frequency band is within the frequency band, the swing amplitude of the pendulum weight increases, and the collision force between the piezoelectric beam and the paddle increases, thereby collecting more swing energy of the human body. Moreover, the magnets at both ends of the second semi-cylinder and the magnets on the corresponding end bosses mutually repel magnetic forces, storing the kinetic energy that cannot be converted in time in the form of magnetic potential energy, thereby collecting more human body swing energy.

The invention has the beneficial effects:

By introducing nonlinear stiffness, the captured energy frequency band is broadened, low-frequency swings are converted into high-frequency vibrations in the form of collisions, up-frequency conversion is achieved, and the piezoelectric effect is used to convert human body swing energy into electrical energy.

Description of drawings

Figure 1 is a schematic plan view of the present invention;

Figure 2 is a perspective view of the present invention;

Figure 3 is a structural perspective view of the pendulum weight in the present invention;

Figure 4 is a schematic diagram when the position of the boss is adjusted to be closest to the pendulum weight in the present invention.

Detailed ways

The embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

Referring to Figures 1, 2, and 3, the collision upconversion piezoelectric energy capture device proposed by the present invention for collecting human body swing energy consists of a paddle 1, a piezoelectric beam 2, a pendulum 3, a rotating shaft 4, a magnet 5, and a circular shell. The base 6 is composed of a boss; the circular shell base 6 includes an integrally formed annular shell and a circular base; the rotating shaft 4 and the circular base are coaxially arranged, and the rotating shaft 4 and the circular base form a rotating pair. The pendulum weight 3 includes a first semi-cylinder and a second semi-cylinder formed in one piece. The radius of the first semi-cylinder is 2 mm larger than the radius of the rotating shaft 4, and the radius of the second semi-cylinder is 4 mm smaller than the inner diameter of the annular shell; the pendulum weight 3 has a Half of the central hole is located on the first semi-cylinder, and the other half is located on the second semi-cylinder; the central hole of the pendulum weight 3 is fixed on the rotating shaft 4, and a circular hole is opened at both ends of the second semi-cylinder plane, each A magnet 5 is embedded in the round hole. Six piezoelectric beams 2 are evenly distributed and fixed on the rotating shaft 4 along the circumferential direction of the rotating shaft 4 . Six paddles 1 evenly distributed along the circumferential direction are fixed on the inner wall of the annular shell; the axial position of the paddle 1 relative to the rotating shaft 4 corresponds to the axial position of the piezoelectric beam 2 relative to the rotating shaft 4; in the radial direction of the rotating shaft 4, the dial The distance between the piece 1 and the axis of the rotating shaft 4 is less than the distance between the outer end surface of the piezoelectric beam 2 and the axis of the rotating shaft 4; two bosses are fixed on the inner wall of the annular shell, and the two bosses are respectively located on the second semi-cylinder. At both ends of the plane, the distance between the central axis of the rotating shaft 4 and the two bosses is equal; in the axial direction of the rotating shaft, the distance between the bosses and the piezoelectric beam 2 is set; a magnet 5 is fixed on the opposite surface of the boss and the second semi-cylindrical plane. When the plane of the second semi-cylinder is parallel to the plane of the fixed magnet 5 on the boss, the magnet 5 on the second semi-cylinder is coaxially arranged with the magnet 5 on the boss at the corresponding end and the magnetic poles at the opposite ends are the same. When the energy capture device does not move, the magnets 5 at both ends of the second semi-cylinder are affected by equal repulsive magnetic forces from the magnets 5 on the bosses at both ends, and can be in a balanced position without swinging.

Referring to Figure 1 and Figure 4, an adjustment hole group is provided near the two bosses of the annular shell; the adjustment hole group includes three adjustment holes arranged along the circumference of the annular shell, and each two adjustment holes are The angles between the central axes are equal; the boss is connected to one of the adjustment holes through screws. The boss can be connected to the adjustment holes at different positions, so the up and down position relative to the annular shell can be adjusted, thereby changing the magnet 5 and 5 on the second semi-cylinder. The initial spacing of the magnets 5 on the boss ultimately changes the nonlinear stiffness of the pendulum 3, achieving the purpose of broadening the effective energy capture frequency band of the pendulum 3. Therefore, by adjusting the position of the boss, the working frequency of the pendulum weight 3 can more easily match the swing frequency of the human body.

In this embodiment, the magnet is a cylinder, but other shapes can also be used.

The energy harvesting method of the collision upconversion piezoelectric energy harvester that collects human body swing energy is as follows:

When the human body carries the energy capture device, the pendulum 3 is placed horizontally. The pendulum 3 swings around the rotating axis 4 at the human body's swing frequency (less than 10Hz), thereby driving the piezoelectric beam 2 to collide with the paddle 1 through the rotating axis 4, causing the piezoelectric beam to collide with the paddle 1. The beam 2 vibrates at high frequency to realize the transformation from low frequency to high frequency (50-500Hz); the high-frequency vibration of the piezoelectric beam 2 can generate electric energy, thereby achieving the purpose of energy capture. The combination of multiple piezoelectric beams 2 and paddles 1 collides, effectively increasing the output power. When the pendulum 3 swings, the magnets at both ends of the second semi-cylinder and the magnets on the corresponding end bosses mutually repel magnetic forces, introducing nonlinear stiffness to the pendulum 3, thus broadening the effective energy capture band of the pendulum 3. When the human body swings When the frequency is within the effective energy harvesting frequency band of pendulum 3, the swing amplitude of pendulum 3 is significant, the collision force between piezoelectric beam 2 and paddle 1 increases, and the energy capture device can collect more swing energy, making the energy capture device operate more efficiently. Efficiently generate electricity over a wide frequency band. Moreover, the magnets at both ends of the second semi-cylinder and the magnets on the corresponding end bosses mutually repel magnetic forces, which can store kinetic energy that cannot be converted in time in the form of magnetic potential energy, thereby collecting more swing energy.

The collision-upconverting piezoelectric energy capture device proposed by the present invention to collect human body swing energy can broaden the energy capture frequency band by introducing nonlinear stiffness in a low-frequency environment, and convert low-frequency swing into high-frequency vibration in the form of collision, achieving Up-conversion uses the piezoelectric effect to convert human body swing energy into electrical energy.

Claims (2)

1. Collect collision frequency-raising type piezoelectric energy harvester of human body swing energy, its characterized in that: consists of a poking piece, a piezoelectric beam, a swinging weight, a rotating shaft, a magnet, a circular shell base and a boss; the circular shell base comprises an integrally formed circular shell and a circular base; the rotating shaft and the circular base are coaxially arranged, and form a revolute pair; the pendulum weight comprises a first semi-cylinder and a second semi-cylinder which are integrally formed, the radius of the first semi-cylinder is 2-4 mm larger than the radius of the rotating shaft, and the radius of the second semi-cylinder is 4-6 mm smaller than the inner diameter of the annular shell; one half of the center hole formed in the pendulum weight is positioned on the first semi-cylinder, and the other half of the center hole is positioned on the second semi-cylinder; the central hole of the pendulum weight is fixed on the rotating shaft, two ends of the plane of the second semi-cylinder are respectively provided with a round hole, and a magnet is embedded in each round hole; n piezoelectric beams are uniformly distributed and fixed on the rotating shaft along the circumferential direction of the rotating shaft, wherein n is more than or equal to 4 and less than or equal to 8; n poking sheets uniformly distributed along the circumferential direction are fixed on the inner side wall of the annular shell; in the axial direction of the rotating shaft, the poking piece is aligned with the piezoelectric beam; in the radial direction of the rotating shaft, the distance between the shifting piece and the axis of the rotating shaft is smaller than the distance between the end face of the outer end of the piezoelectric beam and the axis of the rotating shaft;

two bosses are fixedly arranged on the inner side wall of the annular shell, the two bosses are respectively arranged at two ends of the plane of the second semi-cylinder, and the distance between the central axis of the rotating shaft and the two bosses is equal; in the axial direction of the rotating shaft, the lug boss is arranged at intervals with the piezoelectric beam; a magnet is fixed on the opposite surface of the boss and the second semi-cylindrical plane; in a state that the plane of the second semi-cylinder is parallel to the plane of the boss fixing magnet, the magnet on the second semi-cylinder and the magnet on the boss at the corresponding end are coaxially arranged, and the magnetic poles at the opposite ends are the same;

the annular shell is provided with an adjusting hole group at the position close to the two bosses; the adjusting hole group comprises three adjusting holes circumferentially distributed along the annular shell, and the included angles of central axes of every two adjusting holes are equal; the boss is connected with one of the adjusting holes through a screw; the magnet is a cylinder.

2. The energy harvesting method of the collision frequency-increasing piezoelectric energy harvester for collecting human body swing energy according to claim 1, wherein the energy harvesting method is characterized by comprising the following steps of: the method comprises the following steps: when the electric bicycle is carried, the pendulum weight is horizontally placed, and swings around the rotating shaft under the human body swinging frequency, so that the piezoelectric beam is driven to collide with the poking piece through the rotating shaft, and the piezoelectric beam is vibrated at high frequency to generate electric energy; when the pendulum weight swings, the magnets at the two ends of the second semi-cylinder and the magnets on the bosses at the corresponding ends repel each other to act, nonlinear rigidity is introduced to the pendulum weight, the effective energy capturing frequency band of the pendulum weight is widened, when the human body swinging frequency is within the effective energy capturing frequency band of the pendulum weight, the swing amplitude of the pendulum weight is increased, and the collision force between the piezoelectric beam and the plectrum is increased, so that more human body swinging energy is collected; and the magnets at the two ends of the second semi-cylinder and the magnets on the bosses at the corresponding ends mutually repel and magnetically act, so that kinetic energy which cannot be timely converted is stored in a magnetic potential energy form, and more human body swing energy is collected.