JP2017175676A - Power generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power generator capable of achieving size reduction by performing resonance at a low frequency of approx. several Hz generated by an activity of a person or an animal when an object on which a power generator is installed is the person or the animal.SOLUTION: The power generator is structured to include: a conical spring with a fixed terminal and a movable terminal; a movable element mounted on a movable end on the opposite side to a free length of the conical spring; and a power generation part performing power generation by movable element's vibration, thereby achieving resonance at a low frequency and power generation and size reduction.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a power generation device, and more particularly, to a power generation device that generates electric power by vibrating motion of a mover.

  In recent years, an energy harvesting technique has been proposed in which minute energy such as light, heat, and vibration is converted into electrical energy and collected. By using a power generation device using environmental power generation technology, for example, a power generation device can be attached to a bridge, a building, an animal, a person, or the like to be a power source for various electronic devices. Accordingly, it is possible to secure a self-supporting independent power source in various environments and drive the electronic device for a long time without requiring battery replacement or secondary battery charging.

  In a type of energy harvesting that generates power by vibration of an object, it is designed to efficiently convert kinetic energy due to vibration into electrical energy using a mechanism that resonates at a frequency at which the object vibrates (Patent Document 1, 2 etc.). Such a resonance type energy harvesting is extremely inferior in power generation efficiency except at the resonance frequency, so it is important to adjust the resonance point of the power generation device to the vibration of the object to lower the Q value.

JP 2014-050204 A JP 2011-172351 A

However, in particular, when the target to which the power generation device is attached is a person or an animal, the frequency generated by the activity of the person or animal is low and has a feature of about several Hz (about 1.9 Hz in the case of a person). In the case of resonance using a spring and a mover, if the spring constant is k, the mover mass is m, the frequency is ν, and the amplitude is A, the vibration energy E

It is expressed as Therefore, in order to collect as much energy as possible from low-frequency vibrations, it is necessary to increase the mass m of the mover or to decrease the spring constant k so that the amplitude is increased by resonance at a low frequency.

However, increasing the mass m of the mover is not preferable because it reduces the size and portability of the power generation device. Further, if the spring constant k is reduced, the amount of displacement of the spring due to the mass m of the mover increases, so that it is difficult to reduce the size of the tension spring, and the compression spring is buckled.

FIG. 5 is a schematic diagram for explaining vibration of a mover using a conventional tension spring. FIG. 5A shows a free length L0 in a state where no load is applied to the tension spring, and FIG. The displacement and amplitude due to the mover are shown. Assuming that the free length L0 is in a state where no load is applied to the tension spring 1, the amount of displacement by the weight when the fixed end 1a of the tension spring 1 is fixed to the fixed portion 2 and the movable element 3 is attached to the movable end 1b. x, amplitude A, and the total length L1 necessary for vibration are as shown in FIG.


It becomes the relationship. As described above, in the vibration using the conventional tension spring 1, the total length L1 necessary for obtaining the amplitude A is increased, and it is difficult to reduce the size of the power generation apparatus.

Therefore, the present invention has been made in view of the above-described conventional problems, and an object thereof is to provide a power generator that can resonate at a low frequency of about several Hz and can be downsized.

In order to solve the above problems, a power generator according to the present invention comprises a cone spring having a fixed end and a movable end, and has a mover attached to the movable end on the side opposite to the free length of the cone spring. And a power generation unit that generates power by vibration of the mover.

In such a power generator of the present invention, since the movable element is attached by inverting the movable end on the opposite side to the free length of the cone spring, the distance between the center position of the amplitude and the fixed end can be reduced. Thus, it is possible to reduce the overall length necessary for vibration and to reduce the size.

In one embodiment of the present invention, a natural frequency of the cone spring and the mover is in a range of 0.1 to 5 Hz.

  In one embodiment of the present invention, a spring constant of the cone spring is in a range of 0.005 to 0.05 N / mm.

  In one embodiment of the present invention, the fixed end is a side having a larger radius of curvature.

  In one embodiment of the present invention, the mover is a magnet, and the magnet vibrates inside the coil.

  In one embodiment of the present invention, the mover is a coil, and the coil vibrates in the vicinity of the magnet.

In one embodiment of the present invention, the mover is a motor, and includes a conversion mechanism that converts the vibration of the motor into a rotational motion to rotate the shaft of the motor.

In the present invention, it is possible to provide a power generator that resonates at a low frequency of about several Hz and can be miniaturized.

It is a schematic cross section which shows the electric power generating apparatus 10 in 1st Embodiment. FIGS. 2A and 2B are schematic diagrams for explaining vibrations caused by the conical spring 11 and the magnet 13. FIG. 2A shows a free length when no load is applied to the conical spring 11, and FIG. The vibration is shown with the end 11a and the movable end 11b reversed. It is a schematic cross section which shows the electric power generating apparatus 20 in 2nd Embodiment. It is a schematic cross section which shows the electric power generating apparatus 30 in 3rd Embodiment. FIG. 5A is a schematic diagram for explaining vibration of a mover using a conventional tension spring. FIG. 5A shows a free length L0 when no load is applied to the tension spring, and FIG. The displacement and amplitude are shown.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings. The same or equivalent components, members, and processes shown in the drawings are denoted by the same reference numerals, and repeated descriptions are omitted as appropriate. FIG. 1 is a schematic cross-sectional view showing a power generation device 10 according to this embodiment. The power generation device 10 includes a conical spring 11 serving as a cone spring, a fixed portion 12, a magnet 13, a guide 14, a bottom portion 15, and a coil 16.

The conical spring 11 is a member processed in a spiral shape in the height direction while the radius of curvature of the wire gradually decreases from the fixed end 11a to the movable end 11b. Here, the conical spring 11 and a general name are used. However, the conical spring 11 is not necessarily required to have a conical shape. The conical spring 11 may be formed in a spiral shape in a height direction with a gradually decreasing curvature radius. Various shapes such as a shape can be employed. Here, an example is shown in which the radius of curvature on the fixed end 11a side is larger than that on the movable end 11b side, but the radius of curvature on the movable end 11b side may be larger than that on the fixed end 11a side.

The fixed end 11a of the conical spring 11 is fixed to the lower surface of the fixed portion 12, and the movable end 11b is reversed to the side opposite to the free length of the conical spring 11 and a magnet 13 is attached as will be described later. Attachment to the other members of the fixed end 11a and the movable end 11b may be performed using an adhesive or the like, or another jig may be interposed.

The fixed portion 12 is a member for fixing and hanging the fixed end 11 a of the conical spring 11. Although the position where the fixing portion 12 is provided in the power generation device 10 is not limited, by using the top surface of the casing that constitutes the power generation device 10, it is possible to reduce the size of the device while ensuring a distance necessary for vibration.

The magnet 13 is a member that is attached to the movable end 11 b of the conical spring 11 and is suspended and functions as a movable element that vibrates the conical spring 11. Although FIG. 1 shows an example in which the upper movable end 11b side is the N pole and the lower bottom 15 side is the S pole, the N pole and the S pole may be reversed. In the power generation device 10, the magnet 13 vibrates in the vertical direction with an amplitude A at a natural frequency Fn determined by the spring constant k of the conical spring 11 and the mass m of the magnet 13.

When the power generation device 10 is attached to a human body and environmental power generation is performed by vibration caused by human activity, the natural frequency Fn is 0.1 to 5 Hz, more preferably 1 to 3 Hz, and still more preferably 1.6 to 2.2 Hz. It is desirable to select the spring constant k of the conical spring 11 and the mass m of the magnet 13 so as to be in the range. Moreover, in order to improve the portability of the electric power generating apparatus 10, it is preferable that the mass of the magnet 13 is in the range of 30 to 100 g, and the spring constant k of the conical spring 11 is based on the range of the natural frequency Fn and the mass m. Is preferably in the range of 0.005 to 0.05 N / mm.

The guide 14 is a member that extends in the amplitude direction of the magnet 13 and regulates the vibration direction of the magnet 13. The upper portion of the guide 14 is connected to the fixed portion 12, and the lower portion is connected to the bottom portion 15. . Although FIG. 1 shows an example in which the guide 14 is connected to the fixed portion 12 and the bottom portion 15, it is only necessary to be able to regulate the vibration direction of the magnet 13, and it may be provided only in the region of the amplitude A of the magnet 13. Good. The structure of the guide 14 may be a cylindrical member having a cross section substantially the same as the horizontal cross section of the magnet 13 or may be a rail-like member that slides in contact with a part of the magnet 13.

The bottom portion 15 is a member that is positioned below the amplitude region of the magnet 13 and attached to the guide 14. Although the position where the bottom portion 15 is provided in the power generation device 10 is not limited, by using the bottom surface of the casing constituting the power generation device 10, the device can be reduced in size while ensuring a necessary distance for vibration. Although the bottom portion 15 is not necessarily provided, by attaching to the lower end of the guide 14, the magnet 13 is prevented from moving beyond the amplitude region in normal use due to excessive vibration, and the conical spring 11 and the magnet 13 are prevented. And can be protected.

The coil 16 is a member obtained by winding an electrically conductive winding into a cylindrical shape having a predetermined inner diameter, and is arranged so that its central axis coincides with the vibration direction of the magnet 13. As a result, the magnet 13 vibrates inside the coil 16 and power is generated by electromagnetic induction.

Although not shown in FIG. 1, both ends of the winding of the coil 16 are extended to the outside and electrically connected to the circuit unit, and the secondary battery is charged by a rectifier circuit, a voltage conversion circuit, a charging circuit, or the like. In addition, current is supplied to external devices. 1 shows an example in which the coil 16 is disposed outside the guide 14 as a separate body, but the coil 16 and the guide 14 may be integrated or may be disposed inside the guide 14. A plurality of coils 16 may be provided along the vibration direction.

2A and 2B are schematic diagrams for explaining vibrations caused by the conical spring 11 and the magnet 13. FIG. 2A shows a free length when no load is applied to the conical spring 11, and FIG. The vibration in a state where the fixed end 11a and the movable end 11b of the spring 11 are reversed is shown.

  As shown in FIG. 2A, the conical spring 11 has a free length L0 when no load is applied, with the fixed end 11a on the lower side and the movable end 11b on the upper side. When the conical spring 11 is used in the power generation device 10, the conical spring 11 is compressed from above until the fixed end 11a and the movable end 11b are in the same plane, and then the movable end 11b is positioned below the fixed end 11a. The magnet 13 is attached to the movable end 11b while being pulled from below to such a position. Thereby, the movable end 11b is inverted to the side opposite to the free length of the conical spring 11, and the inverted state is maintained by the weight of the magnet 13.

As shown in FIG. 2B, the vibration of the conical spring 11 in the inverted state is caused by the weight of the magnet 13 because the movable end 11b of the conical spring is higher than the fixed end 11a when the free length L0. Where x is the displacement amount and A is the amplitude, the total length L1 required for vibration is

It is represented by

Here, when the mass of the magnet 13 as a mover is m and the spring constant of the conical spring 11 is k, the displacement amount x is

And the natural frequency Fn is

It becomes.

  By using these formulas and appropriately selecting the spring constant k of the conical spring 11 and the mass m of the magnet 13 as the mover, the total length L1 and the natural frequency Fn necessary for vibration can be designed, and power generation Energy collection by the device 10 can be optimized to about 1.9 Hz due to human activity.

In this way, by reversing the conical spring 11 and attaching the magnet 13 as the mover to the movable end 11b on the side opposite to the free length, it is necessary for vibration than the number 2 in the case of using a normal tension spring. The total length L1 can be shortened by 2L0. Therefore, in the power generation device 10 according to the present embodiment, it is possible to resonate at a low frequency of about several Hz while downsizing and efficiently convert vibration energy into electric energy.

  Further, since the conical spring 11 is inverted and used as a tension spring, it is not necessary to increase the spring diameter as a countermeasure against buckling as in the case of a compression spring, and the design freedom of the spring is increased. Moreover, it is not necessary to design a special spring shape, and since the conical spring 11 that can be manufactured with existing facilities is used, the manufacturing cost can be reduced and the mass productivity can be improved.

(Second Embodiment)
Next, a second embodiment of the present invention will be described. A description of portions common to the first embodiment is omitted. FIG. 3 is a schematic cross-sectional view showing the power generation device 20 in the present embodiment. The power generation device 20 includes a conical spring 21, a fixing portion 22, a coil 23, a guide 24, a bottom portion 25, and a magnet 26.

The conical spring 21 includes a fixed end 21a and a movable end 21b. The fixed end 21a is fixed to the lower surface of the fixed portion 22, and the movable end 21b is reversed to the opposite side to the free length of the conical spring 21 to be coil holding portions. 23a is attached. The coil 23 is attached to the coil holding part 23a, is suspended from the movable end 21b of the conical spring 21, and functions as a movable element that vibrates the conical spring 21. The magnet 26 is erected on the bottom portion 25 so that the central axes of the coils 23 coincide with the polar directions of the magnet 26. Although FIG. 3 shows an example in which the coil 23 is disposed inside the guide 24, the coil 23 may be disposed outside the guide 24.

In the present embodiment, the coil 23 and the coil holding portion 23 a serve as the mover of the conical spring 21, and the coil 23 vibrates in the magnetic field of the magnet 26. Therefore, in the power generation device 20, vibrations are collected by electromagnetic induction in the coil 23, where m is the total mass of the coil 23 and the coil holding portion 23 a, and the vibration shown in Equations 3 to 5 is performed.

  Thus, by reversing the conical spring 21 and attaching the coil 23, which is a mover, to the movable end 21b on the side opposite to the free length, it is necessary for vibration than the number 2 in the case of using a normal tension spring. The total length L1 can be shortened by 2L0. Therefore, the power generation apparatus 20 of the present embodiment also resonates at a low frequency of about several Hz while achieving downsizing, and can efficiently convert vibration energy into electric energy.

(Third embodiment)
Next, a third embodiment of the present invention will be described. A description of portions common to the first embodiment is omitted. FIG. 4 is a schematic cross-sectional view showing the power generation device 30 in the present embodiment. The power generation device 30 includes a conical spring 31, a fixing portion 32, a motor 33, a guide 34, a bottom portion 35, and a rack 36.

The conical spring 31 includes a fixed end 31a and a movable end 31b. The fixed end 31a is fixed to the lower surface of the fixed portion 32. The movable end 31b is reversed to the opposite side of the free length of the conical spring 31, and the motor 33 is rotated. It is attached. A pinion gear 33b is attached to the shaft 33a of the motor 33, and the teeth of the rack 36 and the teeth of the pinion gear 33b mesh with each other to constitute a rack and pinion mechanism. In addition, the motor 33 contains a magnet and a coil in the same manner as a normal motor, and a lead wire is extended from a terminal (not shown) to the outside and is electrically connected to a circuit unit. A rectifier circuit, a voltage conversion circuit, a charging circuit, etc. For example, the secondary battery is charged and current is supplied to an external device.

In the present embodiment, the motor 33 becomes a mover of the conical spring 31, and the motor 33 vibrates along the rack 36 as expressed by Equations 3 to 5, where m is the mass of the motor 33. Therefore, in the power generation device 30, the vibration motion of the motor 33 is converted into rotational motion by the rack 36 and the pinion gear 33b, and the motor 33 generates power and collects vibration energy by rotating the shaft 33a.

  In this way, by reversing the conical spring 31 and attaching the motor 33 as a mover to the movable end 31b on the side opposite to the free length, it is necessary for vibration more than the number 2 when a normal tension spring is used. The total length L1 can be shortened by 2L0. Therefore, the power generation device 30 of the present embodiment also resonates at a low frequency of about several Hz while achieving downsizing, and can efficiently convert vibration energy into electric energy.

The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 1 ... Tension spring 2 ... Fixed part 3 ... Movable element 10, 20, 30 ... Power generator 11, 21, 31 ... Conical spring 1a, 11a, 21a, 31a ... Fixed end 1b, 11b, 21b, 31b ... Movable end 12, 22, 32 ... fixed parts 13, 26 ... magnets 14, 24, 34 ... guides 15, 25, 35 ... bottom parts 16, 23 ... coil 23 a ... coil holding part 33 ... motor 33 a ... shaft 33 b ... pinion gear 36 ... rack

Claims (7)

Comprising a cone spring having a fixed end and a movable end;
A mover attached to the movable end on the opposite side of the free length of the spring;
A power generation apparatus comprising a power generation unit that generates power by vibration of the mover. The power generation device according to claim 1,
A natural frequency generated by the cone spring and the mover is in a range of 0.1 to 5 Hz. The power generation device according to claim 1 or 2,
The power generator according to claim 1, wherein a spring constant of the cone spring is in a range of 0.005 to 0.05 N / mm. The power generation device according to any one of claims 1 to 3,
The power generation apparatus according to claim 1, wherein the fixed end is on a side having a larger radius of curvature. The power generation device according to any one of claims 1 to 4,
The power generation device, wherein the mover is a magnet, and the magnet vibrates inside a coil. The power generation device according to any one of claims 1 to 4,
The power generator is characterized in that the mover is a coil and the coil vibrates in the vicinity of a magnet. The power generation device according to any one of claims 1 to 4,
The power generator is provided with a conversion mechanism for converting the vibration of the motor into a rotational motion and rotating the shaft of the motor.