JPH0749388A - Generator - Google Patents

Abstract

(57) [Abstract] [Object] The present invention excites a piezoelectric element or a member coupled to the piezoelectric element by acceleration or displacement, and freely vibrates to generate electric power, thereby making it easy to reduce the size and thickness, and reduce the cost. Achieve an efficient generator for mobile devices. [Structure] 11a is a piezoelectric element, 11b is a metal plate joined to the piezoelectric element and also serving as an extraction electrode, 12 is a weight, 13
Is a fixed part of the generator, 14 is a direction of acceleration or force applied to the entire generator, 15 is a power extraction surface of the piezoelectric element, 16
Is a measure for keeping the displacement of the element within an appropriate range.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to generators.

[0002]

2. Description of the Related Art As a conventional electromagnetic generator, the one shown in FIG. 5 is known.

In FIG. 5, 51 is an unbalanced weight for generating a rotational force, 52 is a gear for extracting the rotational force of the weight, 53 is a speed-increasing gear driven by 52, and 54 is A magnetized magnet rotor driven by 53, 55 is a stator for transmitting magnetic force, and 56 is a generator coil.

In FIG. 5, the direction of gravity changes due to the rotation of the equipment in which the generator is mounted, and when the weight 51 rotates due to imbalance, the rotor 5 passes through the gear 53.
4 is driven, and the magnetic flux in the stator 55 changes. As a result, a current flows through the coil 56 due to the electromagnetic induction phenomenon, and power can be generated.

A conventional electromagnetic generator is disclosed in Japanese Patent Laid-Open No. 52-52
Structures such as -80871 and JP-A-52-82480 are disclosed.

On the other hand, as a conventional piezoelectric generator, the one shown in FIG. 6 is known.

In FIG. 6, 61 is a circular bimorph, 62 is a housing, 63 is an insulator adhered between 61 circular bimorph and the housing of 62, and 64 is a flexible weight provided on the upper surface of the circular bimorph.

When acceleration is applied due to a change in posture of a device equipped with the piezoelectric generator having the above-described structure, a force proportional to the mass of the weight 64 is applied to the circular bimorph 6.
In addition to 1, the circular bimorph 61 is flexibly deformed, and power can be generated by the piezoelectric effect of the bimorph.

A conventional piezoelectric generator is disclosed in Japanese Patent Application Laid-Open No. 48
The structures of JP-A-26088, JP-A-52-127091, and JP-A-56-64677 are disclosed.

[0010]

However, since the conventional electromagnetic generator uses the electromagnetic induction phenomenon for conversion, a coil and a magnet are required. In order to secure sufficient power generation efficiency, a speed increasing mechanism is required. However, there is a problem in that the structure is complicated, it is not suitable for miniaturization and thinning, and it becomes expensive.

On the other hand, the conventional piezoelectric generator is very simple in structure as compared with the electromagnetic generator, so that it is suitable for downsizing and thinning, but it has a drawback that sufficient output cannot be obtained.

The reason why the output is not sufficiently obtained is that the conversion efficiency is low because the portion of the input energy that is stored as distortion of the piezoelectric element itself is much larger than the portion that is converted to electricity by the piezoelectric effect. Since the frequency of acceleration input from the outside is much lower than the resonance frequency of the piezoelectric generator, the operation of the generator is close to static deformation, and sufficient input cannot be obtained.

Therefore, the present invention solves such a problem, and an object of the present invention is to provide a generator for portable equipment which is small in size and thin in thickness, inexpensive, and highly efficient.

[0014]

A power generator of the present invention is characterized in that a piezoelectric element or a member coupled to the piezoelectric element is excited by acceleration or displacement and is freely vibrated to generate electric power.

[0015]

【Example】

(Embodiment 1) FIG. 1 is an assembly view of a main part in an embodiment of the present invention, in which 11a is a piezoelectric element, 11b is a metal plate joined to the piezoelectric element and also serving as an extraction electrode, and 12 is a weight.
13 is a fixed part of the generator, 14 is the direction of acceleration or force applied to the generator, 15 is a power extraction surface of the piezoelectric element, 16
Is a measure for keeping the displacement of the element within an appropriate range. It is also assumed that the piezoelectric element 11a is polarized in the thickness direction.

An arrow 14 is drawn on the whole generator configured as described above.
When an acceleration in the direction of is applied, a force corresponding to the acceleration is applied by the weight 12, and the piezoelectric element 11a and the metal plate 11b are deformed. Electric charges are generated by this deformation and the piezoelectric effect of the piezoelectric element 11a, and a voltage is generated between the surface 15 and the metal plate 11b. When a large acceleration is input, it is possible to prevent an excessive force from being applied to the element due to the contact between the weight 16 and the weight and to prevent damage. Further, the fixed portion 13 is provided on the short side of the vibrator in order to suppress the vibration attenuation.

When a force or motion is converted into electric energy by utilizing the piezoelectric effect, the element has to be deformed, so most of the applied energy is converted into strain energy, which is converted into electric energy. Efficiency is a few percent
It is a degree.

However, if the element is vibrated repeatedly by the stored strain energy to cause deformation, the final conversion efficiency is determined by the ratio of the internal attenuation rate of the element per time and the conversion efficiency into electric energy, and Can be very expensive.

When the generator is used in a portable device such as a watch, acceleration is intermittently applied. Therefore, if the element is freely vibrated during this period and the given energy is converted into electric energy, the above-mentioned efficiency can be obtained. A high generator can be realized.

The output of such a generator is maximized when the frequency of the excitation acceleration is equal to the natural frequency. When the frequency component of acceleration is known in advance, the output can be maximized by adjusting the dimensions of the element and setting the natural frequency in an appropriate region.

(Embodiment 2) FIG. 2 is an assembly view of a main portion in another embodiment of the present invention, in which 21a is a piezoelectric element and 21 is a piezoelectric element.
Reference numeral b is a metal plate joined to the piezoelectric element and also serving as an extraction electrode, 22 is a cam for forcibly displacing the element, 23 is a fixed part of the generator, 24 is the rotational direction of the cam, and 25 is power extraction of the piezoelectric element. The surface. The piezoelectric element 21a is polarized in the thickness direction. The cam is driven by an unbalanced weight.

The cam 22 of the generator constructed in this way
When is rotated in the direction of arrow 24, the piezoelectric element 11a and the metal plate 11b are deformed. Due to this deformation, electric charges are generated between the power extraction surface 25 of the piezoelectric element and the metal plate 21b.

The shape of the cam is rapidly changed to 21 after displacement.
If a and b are released, the element can freely vibrate, and the stored strain energy can be efficiently converted into electric energy as in the first embodiment.

(Embodiment 3) FIG. 3 is an assembly view of a main portion in another embodiment of the present invention, in which 31a is a piezoelectric element and 31 is a piezoelectric element.
Reference numeral b is a tuning fork type metal portion joined to a piezoelectric element and also serving as an extraction electrode, 32 is a bearing mounted so that the element rotates, 33 is a peripheral portion where a generator is mounted, 34
Is a rotating direction of the entire tuning fork type element, and 35 is a contact portion for limiting the rotation.

When acceleration is applied by rotation of a portable device having a generator constructed as described above and the like, the element starts to move in the direction of arrow 34 around the bearing 32. However, when it is rotated to a certain angle, the element collides 35 times per degree and the direction of rotation can be changed. Strain is given by the impulse at this time, and the element vibrates with this as an initial displacement. The vibration can be converted into electric power by the piezoelectric element 31b.

Further, since the mechanism uses the mass of the element itself, the number of parts is small, and an inexpensive, compact and thin generator can be constructed. Further, since the piezoelectric element is arranged so as not to receive an impact directly, it has high durability.

In this structure, since it is not necessary to match the natural frequency of the element with the frequency of the input acceleration, the degree of freedom of shape of the element is high. Further, by sufficiently increasing the natural frequency, the conversion time between vibration and electric power can be made extremely short, and it is possible to cope with the case where the input acceleration changes at a high frequency. Further, by making the metal part a tuning fork type, the bearing 32 can be fixed without affecting the vibrating part.

(Embodiment 4) FIG. 4 is an assembly view of a main portion in another embodiment of the present invention, in which 41 is a piezoelectric element, 42 is a weight, 43 is a fixed portion of the piezoelectric element, and 44 is a swing of a weight. Arrows indicating the directions of motion and acceleration, and 45 are leaf springs coupled to the piezoelectric element.

When acceleration in the direction indicated by arrow 44 is applied to the generator configured as described above, a force proportional to the mass of the weight and the acceleration is transmitted to the piezoelectric element 41 via the spring 45.
Electric power can be taken out by this force and the piezoelectric effect of the piezoelectric element 41. Further, by forming the piezoelectric element 41 as a laminated type, it is possible to increase the generated charges.

By attaching the weight via the spring, the natural frequency of the entire generator can be determined without being significantly affected by the natural frequency of the piezoelectric element itself. The natural frequency of the generator can be easily adjusted to the frequency of the input acceleration, and the power generation output can be increased.

Further, since the masses are coupled via the spring, the piezoelectric element will not be damaged even when the acceleration is shocked. Also, such an input can be converted into electric energy.

[0032]

As described above, according to the present invention, a piezoelectric element or a member coupled to the piezoelectric element is excited by acceleration or displacement, and is freely vibrated to generate power.
This has the effect that it is possible to configure a generator for portable equipment that is easy to make small and thin, inexpensive, and highly efficient.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a main part in an embodiment of the present invention.

FIG. 2 is a configuration diagram of a main part in another embodiment of the present invention.

FIG. 3 is a configuration diagram of a main part in another embodiment of the present invention.

FIG. 4 is a configuration diagram of a main part in another embodiment of the present invention.

FIG. 5 is a configuration diagram of a conventional electromagnetic generator.

FIG. 6 is a configuration diagram of a conventional piezoelectric generator.

[Explanation of symbols]

11a --- Piezoelectric element 11b --- Metal plate joined to the piezoelectric element and also serving as an extraction electrode 12 --- Weight 13 --- Fixed part of generator 14 --- Direction of acceleration or force applied to the entire generator 15 --- Piezoelectric Electric power extraction surface of the element 16 --- Per degree to keep the displacement of the element within an appropriate range 21a --- Piezoelectric element 21b --- Metal plate bonded to the piezoelectric element and also serving as the extraction electrode 22 --- Displacement to the piezoelectric element Giving cam 23 --- Generator fixed part 24 --- Cam rotation direction 25 --- Power extraction surface of piezoelectric element 31a --- Piezoelectric element 31b --- Tuning fork type metal plate 32 --- Bearings mounted to rotate 33 --- Frame fixed to the generator 34 --- Rotation direction of bearing 35 --- Proper range of displacement Time per 41 to fit in - the piezoelectric element 42 - weight 43 - frame is the generator fixed 44 - applied to the entire generator acceleration or force direction 45 - a leaf spring coupled to the piezoelectric element

Claims (16)

[Claims] 1. A power generator having a piezoelectric element that freely vibrates due to an externally applied acceleration. 2. A generator comprising: a piezoelectric element that freely vibrates by an externally applied acceleration; and a member that is joined to the piezoelectric element and integrally vibrates freely. 3. A piezoelectric element that freely vibrates by an externally applied acceleration, a member that is joined to the piezoelectric element and integrally vibrates freely, and a weight that is coupled to the piezoelectric element or the member. Generator. 4. A generator comprising a mechanism for converting an acceleration applied from the outside into a displacement and releasing the displacement, and a piezoelectric element which is distorted by the displacement and vibrates freely. 5. A mechanism for converting an externally applied acceleration into a displacement to release the displacement, a member which is distorted by the displacement and which freely vibrates, and a piezoelectric element which is joined to the member and vibrates integrally as a unit. A generator characterized by having. 6. A generator comprising: a piezoelectric element that can rotate or linearly move due to an externally applied acceleration to freely vibrate, and a mechanism that comes into contact with the piezoelectric element. 7. A piezoelectric element, which can rotate or linearly move by an externally applied acceleration to freely vibrate, a member that is joined to the piezoelectric element and freely vibrates integrally, and a mechanism that contacts the piezoelectric element or the member. A generator characterized by. 8. The generator according to claim 1, wherein the frequency of free vibration is set in a region where the frequency component of the acceleration to be excited is high in frequency. 9. The generator according to claim 1, wherein the piezoelectric element or the member coupled to the piezoelectric element has a cantilever shape. 10. The generator according to claim 1, wherein the piezoelectric element or a member connected to the piezoelectric element has a tuning fork shape. 11. The generator according to claim 1, wherein the piezoelectric element or a member coupled to the piezoelectric element has a disk shape. 12. The generator according to claim 1, wherein a plurality of piezoelectric elements are used in the generator. 13. The generator according to claim 1, wherein the piezoelectric element used in the generator is a laminated piezoelectric element. 14. The generator according to claim 1, wherein a contact is provided to keep the amplitude within an appropriate range. 15. The generator according to claim 6, wherein the mechanism capable of rotating or linearly moving by an externally applied acceleration is a spring. 16. The generator according to claim 6, wherein the mechanism capable of rotating or linearly moving by an externally applied acceleration is a bearing.