JPH11341837A - Piezoelectric-type power device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric-type power device which efficiently utilizes and stores electrical energy obtained, even when its piezoelectric element is vibrating at a non-resonance frequency also. SOLUTION: A transistor T1 is turned on, when the positive part of a piezoelectric voltage VP is applied from a piezoelectric element 30 and a resistor element R1. Since a current flows into the transistor T1 from a smoothing capacitor C1 through a solenoid coil K1. electromagnetic energy is stored in the solenoid coil K1. Subsequently, when the transistor T1 is turned off, the energy in the solenoid coil K1 is transferred to a storage capacitor C2 through a diode D3. As a result of this, electric charges are stored in the storage capacitor C2. By repeating the on/off operation of the transistor T1 after that, electric charges are stored in the storage capacitor C2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a piezoelectric power supply device using a piezoelectric element.

[0002]

2. Description of the Related Art Conventionally, for example, power is supplied to various devices mounted on an automobile or the like from a power generator such as a power generator via a power supply line or by using a battery. by the way,
Usually, the power generation device has a large external shape, is fixed to a stationary member, and has a long power supply line. For this reason, when the power supply location is a movable part of a device in a narrow space, it is difficult to dispose the power generation device near the movable part, and wiring is difficult, poor contact, power loss, etc. Easy to invite.

Therefore, it is difficult to easily and satisfactorily supply power to a movable portion of a device via a power supply line. Further, in the case of using a battery, there is a problem in the life of the battery even if it can be charged. Therefore, there is a demand for the development of a small power supply device having a semi-permanent life and capable of supplying power to a movable portion of a device satisfactorily and easily without using long wiring.

On the other hand, Japanese Patent Application Laid-Open No. Sho 59-194677 discloses
As disclosed in Japanese Patent Application Laid-Open Publication No. H10-209, a power supply device that converts mechanical energy into electrical energy by using a piezoelectric element has been proposed. Specifically, in this power supply device, the piezoelectric voltage generated by the piezoelectric element is rectified by a rectifier circuit, and electrical energy based on the rectified voltage is stored in a storage capacitor.

[0005]

By the way, in the above power supply device, when the piezoelectric element vibrates at the resonance frequency, the maximum electric energy is obtained. Therefore, when the piezoelectric element vibrates at the resonance frequency, electric energy based on the piezoelectric voltage is sufficiently stored in the storage capacitor.

However, when the piezoelectric element vibrates at a frequency other than the resonance frequency, the voltage of the piezoelectric element may be lower than the voltage stored in the storage capacitor.
In such a case, the electrical energy based on the piezoelectric voltage is
Not stored in the storage capacitor. Therefore, there is a problem that electric energy when the piezoelectric element vibrates at a frequency other than the resonance frequency is wasted.

Accordingly, the present invention has been made in view of the above-mentioned problems, and a piezoelectric type which employs boosting means and efficiently utilizes and stores electric energy when a piezoelectric element vibrates at a non-resonant frequency. It is an object to provide a power supply device.

[0008]

According to the first aspect of the present invention, a piezoelectric element (3) is provided.
A piezoelectric vibrator comprising a piezoelectric vibrator (P) for generating a piezoelectric voltage from the piezoelectric element in accordance with the vibration thereof; and a rectifying means (40) for rectifying the piezoelectric voltage to generate a rectified output. And a storage capacitor (C2) that is charged according to the rectified output and generates a storage voltage, provided between the rectifier (40) and the storage capacitor (C2). And a boosting means (50) for boosting the voltage and storing it in the storage capacitor (C2).

As described above, since the rectified output is boosted and stored in the storage capacitor (C2), the piezoelectric power supply device can efficiently store electric energy when the piezoelectric element vibrates at the resonance frequency. Needless to say, the piezoelectric element (3
0, 31) can also efficiently store electrical energy when vibrating at a non-resonant frequency. Further, in the invention described in claim 2, the piezoelectric element (30, 3
A piezoelectric vibrator (P), comprising: a piezoelectric vibrator comprising:
Rectifying means (40) for rectifying the piezoelectric voltage to generate a rectified output, a storage capacitor (C2) for storing a stored voltage in accordance with the rectified output, and generating a regulator voltage based on the stored voltage. In the piezoelectric power supply device provided with a regulator (70), a rectified output is provided between the rectifying means (40) and the storage capacitor (C2) to boost the rectified output to generate a boosted voltage and to be stored in the storage capacitor (C2) A boosting means (50) for reducing the pressure.

In this case, the same operation and effect as the first aspect of the invention can be obtained. Further, as in the third aspect of the present invention, the step-up means (50) according to the first or second aspect includes:
A semiconductor switching element (T1) that performs a switching operation based on a piezoelectric voltage;
A boosting element (K1) for boosting the rectified output in accordance with the switching operation of 1) and storing the boosted output in the storage capacitor (C2) may be provided.

[0011]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing a first embodiment of the present invention. FIG. 1 shows an example in which a piezoelectric power supply device according to the present invention is applied to a tire condition sensor device 10. This power supply device is provided on an outer peripheral wall of a tire rim in a tire of the vehicle. ing.

As shown in FIGS. 2 and 3, the power supply device includes a piezoelectric vibrator P. The piezoelectric vibrator P is fitted in a part of the tire rim 20 at a fixed portion thereof, and the piezoelectric vibrator P extends in a radial direction and an outward direction (rightward in the drawing) of the tire. . The piezoelectric vibrator P is shown in FIG.
As shown in FIG. 3, a vibration member P1 is provided. As shown in FIG.
It is configured such that a metal plate 32 is sandwiched between 31. The two piezoelectric elements 30 and 31 are electrically connected in series via a metal plate 32. The vibrating member P1 has a positive electrode 33 on the outer surface of the piezoelectric element 30 and a negative electrode 34 on the outer surface of the piezoelectric element 31.

As shown in FIGS. 2 and 3, the piezoelectric vibrator P has a weight P2, and the weight P2 is fixed to the tip of the piezoelectric vibrator P. As a result,
When vibration is applied to the rim, the piezoelectric vibrator P vibrates up and down as shown in FIG. 2 based on the fixed end in response to the vibration.
Accordingly, the piezoelectric vibrator P converts the vibration into a piezoelectric voltage having an AC waveform, and generates the piezoelectric voltage between the electrodes 33 and 34 of the vibration member P1.

The power supply device has a rectifier circuit 40. The rectifier circuit 40 is configured by a full-bridge circuit composed of a diode, and the rectifier circuit 40 performs full-wave rectification on a piezoelectric voltage generated from the vibration member P1. Each input terminal of the rectifier circuit 40 is connected to both electrodes 33 of the vibration member P1,
34 respectively. In addition, the power supply device includes a smoothing capacitor C1, which smoothes the rectified voltage output from the rectifier circuit 40. Note that both terminals of the smoothing capacitor C1 are connected to both output terminals of the rectifier circuit 40, respectively.

The power supply includes a booster circuit 50. The booster circuit 50 includes a transistor T1, and the transistor T1 is turned on by applying a positive portion of the piezoelectric voltage from the vibration member P1 through the diode D2 and the resistor R1. Note that the transistor T1 has N
It is composed of a PN transistor. The diode D2 has an anode terminal connected to the positive electrode 33 of the vibrating member P1 and a cathode terminal connected to the base terminal of the transistor T1 through the resistor R1. The piezoelectric voltage of the vibrating member P1 is rectified to output a positive portion of the piezoelectric voltage. Further, the Zener diode Z1 prevents the transistor T1 from being damaged by an excessive piezoelectric voltage.

Further, the booster circuit 50 includes an electromagnetic coil K1, and this electromagnetic coil K1 exerts an electromagnetic induction action in accordance with the switching operation of the transistor T1.
Specifically, when the transistor T1 is turned on, the energy stored in the electromagnetic coil K1 is transferred to the storage capacitor C2 through the diode D3 as the transistor T1 is turned off, and the voltage of the storage capacitor C2 increases. The electromagnetic coil K1 is connected between the collector terminal of the transistor T1 and the positive terminal of the storage capacitor C2.

The booster circuit 50 includes a backflow preventing diode D3, which prevents a current from flowing from a storage capacitor C2 described later to the electromagnetic coil K1. The power supply device is a storage capacitor C2.
The storage capacitor C2 is charged according to the current supplied from the electromagnetic coil K1 through the diode D3.

Further, the power supply device includes an operation interval determination circuit 60.
The operation interval determination circuit 60 includes a timer 6
1 is provided. The timer 61 determines the ON / OFF cycle of the transistor F1 described later by the charge / discharge circuit. Note that this charge / discharge circuit includes a storage capacitor C
2 through the resistance element R2 to repeat charging and discharging at a predetermined cycle.

The operation interval determination circuit 60 includes a transistor F1. The transistor F1 is controlled to be turned on and off by a charging / discharging circuit of a timer 61 at a charging / discharging cycle. Note that the transistor F1 is composed of a P-channel field effect transistor. Further, the power supply device includes a regulator 70. The regulator 70 is supplied with power from the power storage capacitor C2, generates a regulator voltage, and outputs it to the tire condition sensor device 10.

The tire condition sensor device 10 includes a tire sensor and a transmitter provided on an outer peripheral wall of a tire rim. Each time the tire condition sensor device 10 is supplied with power from the regulator 70, the tire sensor measures the tire air pressure and its temperature, and the measured data is provided as radio waves in the vehicle interior of the vehicle by the transmitter. Send to receiver. The power is supplied from the regulator 70 to the tire sensor and the transmitter.

In the power supply device configured as described above,
When the piezoelectric vibrator P is vibrated through the tire rim of the vehicle, the vibrating member P1 vibrates and generates a piezoelectric voltage having an AC waveform (refer to a symbol VP in FIG. 4). Then, the rectifier circuit 40 performs full-wave rectification on the piezoelectric voltage VP of the vibration member P1 and outputs a full-wave rectified voltage (see reference numeral V0 in FIG. 5).

Then, the smoothing capacitor C1 smoothes the full-wave rectified voltage V0 to generate a smoothed voltage (see reference numeral V1 in FIG. 5). The smoothed voltage V1 is about 0.7 times the peak voltage of the full-wave rectified voltage V0. Then
The transistor T1 is connected from the vibration member P1 to the diode D2.
When the positive portion of the piezoelectric voltage VP is applied through the resistor R1 and the resistor R1, the transistor turns on. Then, a current flows from the smoothing capacitor C1 to the transistor T1 through the electromagnetic coil K1, so that electromagnetic energy is stored in the electromagnetic coil K1.

Thereafter, when the transistor T1 is turned off,
The energy of the electromagnetic coil K1 is transferred to the storage capacitor C2 through the diode D3. This allows
The storage capacitor C2 is stored. Since then
As described above, when the transistor T1 is repeatedly turned on and off, the power storage capacitor C2 is charged.

The timer 61 is charged and discharged by the charging / discharging circuit by the storage capacitor C2. Therefore, the transistor F1 is repeatedly turned on and off at a constant cycle. Therefore, the regulator 7
0 is intermittently supplied from the storage capacitor C2 through the transistor F1 at a constant cycle. The regulator 70 applies a regulator voltage to the tire condition sensor device 10 each time power is supplied from the storage capacitor C2.

As described above, in the power supply device, electromagnetic energy is stored in the electromagnetic coil K1 while the transistor T1 is repeatedly turned on and off, and this energy is transferred to the power storage capacitor C2 through the diode D3. For this reason, it is possible to efficiently utilize the entire piezoelectric voltage VP of the vibration member P1 including the piezoelectric voltage VP in which the vibration member P1 is in a non-resonant state, and efficiently store the electric power in the electric storage capacitor C2.

In the above embodiment, a field effect transistor may be used as the transistor T1 in the booster circuit 60. Further, in the above embodiment, a PNP transistor may be employed instead of the NPN transistor T1. In this case, instead of connecting the anode terminal of the diode D2 to the positive electrode 33 of the vibration member P1, as shown in FIG.
Type transistor connected to the base terminal
The second cathode terminal is connected to the positive electrode 33 of the vibration member P1.

With such a configuration, the PNP transistor is turned on by applying a negative portion of the piezoelectric voltage. Further, in the above-described embodiment, the example in which the piezoelectric power supply is mounted on the vehicle has been described. However, the present invention is not limited to this. The present invention may be applied and implemented.

[Brief description of the drawings]

FIG. 1 is an electric circuit diagram showing an embodiment of a piezoelectric power supply device for a vehicle according to the present invention.

FIG. 2 is a side view showing the piezoelectric vibrator of FIG.

FIG. 3 is a perspective view showing the piezoelectric vibrator.

FIG. 4 is a timing chart showing an output of the vibration member of FIG. 1;

FIG. 5 is a timing chart showing respective outputs of a rectifier circuit 40 and a smoothing capacitor of FIG. 1;

[Explanation of symbols]

30, 31: piezoelectric element, 40: rectifier circuit, 50: booster circuit, 70: regulator, C2: storage capacitor, K
1: electromagnetic coil, P: piezoelectric vibrator, T1: transistor.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor, Michiyasu Moritsugu, 14 Iwatani, Shimowakaku-cho, Nishio-shi, Aichi Japan (72) Inventor, Mamoru Ishikiriyama 1-Toyota-cho, Toyota-cho, Toyota-shi, Aichi Automobile Co., Ltd.

Claims (3)

[Claims] 1. A piezoelectric vibrator (P) comprising a piezoelectric element (30, 31), wherein a piezoelectric vibrator (P) for generating a piezoelectric voltage from the piezoelectric element in accordance with the vibration thereof; A piezoelectric power supply device comprising: a rectifier (40) for generating an output; and a storage capacitor (C2) that is stored in accordance with the rectified output to generate a storage voltage. Capacitor (C
2) A piezoelectric power supply device comprising: a boosting means (50) provided between the two for boosting the rectified output and storing the boosted voltage in the storage capacitor (C2). 2. A piezoelectric vibrator comprising a piezoelectric element (30, 31), wherein the piezoelectric vibrator (P) generates a piezoelectric voltage from the piezoelectric element in accordance with the vibration thereof; A rectifier (40) for generating an output, a storage capacitor (C2) that is stored according to the rectified output to generate a storage voltage, and a regulator (70) that generates a regulator voltage based on the storage voltage. The rectifying means (40) and the storage capacitor (C
2) A piezoelectric power supply device comprising: a boosting means (50) provided between the boosting means and boosting the rectified output and storing the boosted voltage in the storage capacitor (C2). 3. The boosting means (50) is a semiconductor switching element (T1) that performs switching operation based on the piezoelectric voltage, and boosts the rectified output according to the switching operation of the semiconductor switching element (T1) to store the electric power. 3. The piezoelectric power supply device according to claim 1, further comprising: a boosting element (K1) for storing electricity in the capacitor for use (C2). 4.