JP2014138545A - Power generator and detection system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure high power generation efficiency without taking time and trouble.SOLUTION: The power generator includes: a power generation element 11 whose one end is connected with a vibration source and whose other end 11b is used as a fee end and which generates electric power by vibration of the vibration source; a weight 22 which is mounted to be movable along such a direction as connects one end with the other end 11b of the power generation element 11; movement means 24 that moves the weight 22; a measurement section which measures an output of the power generation element 11; and a control section which controls movement of the weight 22 by the movement means 24 according to an output level of the measured power generation element 11.

Description

  The present invention relates to a power generation apparatus and a detection system including a power generation element that generates power by vibration of the power generation element.

  Sensor devices that detect various state quantities require a power source for their operation, but when the power source is a commercial AC power source or a battery, wiring is required between the sensor and the power source. It is. For this reason, these are expensive, and in order to ensure the space for providing wiring, size reduction of a sensor apparatus may be prevented.

On the other hand, in recent years, a piezoelectric element is provided on a measurement target, electric power is generated by the piezoelectric element due to vibration or distortion generated in the measurement target, and this power is being used as a power source.
For example, Patent Document 1 discloses a configuration of a vibration detection device such as a bearing of a rotary machine, in which a piezoelectric element attached to the bearing covers the amount of electricity necessary for the vibration detection device by power generated by the vibration of the bearing. ing.

  Further, in Patent Document 1, by attaching a weight to a piezoelectric element and adjusting the weight and the attachment position of the weight with respect to the piezoelectric element, the natural frequency of the piezoelectric element is adjusted to the vibration frequency band of the bearing to be measured. A configuration is disclosed. This configuration is intended to increase the amount of power generated in the piezoelectric element.

Japanese Patent Laid-Open No. 9-264778

However, in the configuration described in Patent Document 1, when the vibration frequency band generated in the measurement object fluctuates for some reason, the power generation efficiency in the piezoelectric element is reduced.
In addition, since the weight is attached to the piezoelectric element by a screw, even when the screw is loosened and the weight is displaced, the power generation efficiency in the piezoelectric element is lowered.
In these cases, there is a problem that it is necessary to readjust the weight of the weight with respect to the piezoelectric element and the attachment position, which takes time.

  Such a problem is not limited to the vibration detection device, but is common to devices including a power generation element such as a piezoelectric element that generates power by vibration of a vibration source.

  An object of the present invention made there is to provide a power generation device and a detection system capable of constantly maintaining high power generation efficiency without taking time and effort.

The present invention employs the following means in order to solve the above problems.
That is, the power generation device of the present invention includes a power generation element that is connected to a vibration source at one end and the other end is a free end and generates power by vibration of the vibration source, and the one end and the other end with respect to the power generation element. A weight provided so as to be movable along the connecting direction, a moving means for moving the weight, a measurement unit for measuring an output from the power generation element, and an output level of the power generation element measured by the measurement unit And a control unit that controls the movement of the weight by the moving means and adjusts the natural frequency of the power generating element.

  According to such a power generation device, the control unit automatically controls the natural frequency of the power generation element by controlling the movement of the weight according to the output level of the power generation element when the weight is moved relative to the power generation element. Can be adjusted. Thereby, the natural frequency of the power generation element can be adjusted according to the natural frequency of the vibration source, and the power generation efficiency of the power generation element can be kept high.

  Here, it is preferable that the control unit fixes the weight at a position where the output level of the power generating element reaches a peak when the weight is moved by the moving means.

The control unit may move the weight when the output of the power generation element measured by the measurement unit falls below a predetermined lower limit.
Thereby, when the output of a power generation element falls for some reason, the position adjustment of a weight is automatically performed and the power generation efficiency in a power generation element can be maintained high.

  The present invention also provides a power generation apparatus as described above, a sensor that is attached to the power generation element or the vibration source and detects a state quantity, and receives power supplied from the power generation element, And a wireless transmitter for transmitting to the detection system.

  Such a detection system can secure a power source for transmitting the sensor detection signal to the outside with a wireless transmitter, and also keeps the system stable by keeping the power generation efficiency of the power generation element high. Can be operated.

  According to the present invention, the power generation efficiency can always be kept high without taking time and effort.

It is a figure which shows a mode that the electric power generation element in the detection system which concerns on embodiment of this invention vibrates. It is a figure which shows the functional structure of the detection system which concerns on embodiment. It is a side view which shows the frequency adjustment mechanism of the electric power generation element with which the detection system which concerns on embodiment was equipped. It is a figure which shows the flow of the process which adjusts automatically the frequency of the electric power generation element in the detection system which concerns on this embodiment. It is a figure which shows the flow of the process which adjusts the frequency of the electric power generation element in the modification of this embodiment automatically.

Hereinafter, with reference to an accompanying drawing, the form for carrying out the power generator and detection system by the present invention is explained. However, the present invention is not limited only to these embodiments.
As shown in FIGS. 1 and 2, the detection system 10 detects a state quantity and a power generation element 11 that is provided at an end 1 a of a rotary shaft (vibration source) 1 such as various rotary machines and generates power by its own vibration A sensor element (sensor) 13 (for example, a strain gauge that detects strain due to the axial torque of the rotary shaft 1) and power supply from the power generation element 11 are measured, and a detection signal of the sensor element 13 is measured and wirelessly transmitted. A signal processing unit 14, a power storage element 15 such as a capacitor that is built in the signal processing unit 14 and stores power by receiving power supplied from the power generation element 11, and a natural frequency of the power generation element 11 provided in the power generation element 11. And a frequency adjustment controller (measuring unit, control unit) 25 for controlling the operation of the frequency adjusting mechanism 20.

The power generation element 11 has one end 11 a fixed to the signal processing unit 14. Such a power generation element 11 has a cantilever shape in which one end 11a is a fixed end and the other end 11b is a free end. The signal processing unit 14 is provided on the outer periphery of the rotating shaft 1 and supports the one end 11a of the power generating element 11 at a position (height) spaced radially outward from the surface of the rotating shaft 1, Even when the power generating element 11 vibrates with the maximum amplitude, it does not come into contact with the rotating shaft 1.
The power generation element 11 has a strip shape, for example, having a rectangular cross section from one end 11a to the other end 11b.
Here, the power generating element 11 is formed so as to vibrate (repeatedly elastically deform) with rotation by reducing the cross-sectional secondary moment or using a material having a Young's modulus that can be appropriately elastically deformed.

  When the rotating shaft 1 rotates, the power generating element 11 rotates along with the rotating shaft 1 around its central axis. The rotating shaft 1 itself vibrates by a slight unbalance amount due to eccentricity or the like, or by receiving vibration from a bearing that supports the rotating shaft 1. The power generating element 11 extends along the axis of the rotating shaft 1 and has a thin flat shape in the radial direction. The rigidity differs in the plate width direction Dw (direction perpendicular to the paper surface of FIG. 1) and the plate thickness direction Dt. . As a result, in the power generation element 11, vibration is generated that is repeatedly deformed in the thickness direction Dt at the other end 11 b. At this time, since the natural frequency of the power generation element 11 is equal to or close to the frequency corresponding to the rotation of the rotary shaft 1, the power generation element 11 vibrates with a large amplitude and deforms, thereby generating an electromotive force. Will occur. In FIG. 1, the power generating element 11 is attached to a part of the longitudinal direction, that is, the direction along the axis of the rotating shaft 1, but may be attached to the entire surface. At least when the power generation element 11 vibrates, it is preferable that the power generation element 11 is attached to a position with a large strain. Further, the power generation element 11 is formed by, for example, a piezo element that generates power by converting kinetic energy generated by the vibration of the other end 11b into electric energy, but the power generation element itself is limited to a structure that vibrates in a cantilever shape. Instead of this, an element such as a piezo element that converts kinetic energy into electric energy may be fixed integrally with a cantilever-like elastic body that vibrates with rotation, and may be vibrated together with the elastic body.

  The sensor element 13 detects a state quantity and is fixed to the outer surface 1 b of the rotating shaft 1. For example, the sensor element 13 includes a foil strain gauge or a piezo-type strain sensor for detecting the rotational torque of the rotary shaft 1 and detects the strain of the rotary shaft 1.

  As shown in FIG. 2, the signal processing unit 14 includes a wireless transmission circuit (wireless transmitter) 14 a that operates by receiving power supplied from the power generation element 11 or the storage element 15, and a wireless transmission controller 14 b.

  The wireless transmission circuit 14a receives the detection signal output from the sensor element 13 and transmits it to the outside by radio. In an external receiving device (not shown), by receiving a detection signal from the sensor element 13, it is possible to monitor a torque fluctuation or the like of the rotating shaft 1.

  The wireless transmission controller 14b controls the operation of the wireless transmission circuit 14a. That is, in order to reduce power consumption, the wireless transmission circuit 14a is activated at regular intervals to transmit the detection signal from the sensor element 13 to the outside, and otherwise, the wireless transmission circuit 14a is turned off. Controls like this. Note that the control content in the wireless transmission controller 14b is not limited at all.

  Although it is necessary to electrically connect the power generation element 11 and the sensor element 13 to the signal processing unit 14, the signal processing unit 14 is disposed closer to the power generation element 11 in order to shorten the wiring as much as possible. It is desirable.

  In such a detection system 10, by providing the power generation element 11, it is not necessary to provide a power source outside, and the detection signal of the sensor element 13 can be transmitted wirelessly by the power generated by the power generation element 11. Therefore, wiring from a power source or the like is unnecessary, and detection can be performed over a long period of time without maintenance.

As shown in FIG. 3, the frequency adjustment mechanism 20 that adjusts the natural frequency of the power generation element 11 is provided with a rail 21 that protrudes from the other end 11 b of the power generation element 11 along the longitudinal direction of the power generation element 11. And a weight 22 that is movable along the rail 21 while meshing with the rail 21, a feed screw 23 provided in parallel to the rail 21, and the other end 11 b of the power generating element 11. And a motor (moving means) 24 composed of a micromotor that rotates the motor around its axis.
An internal thread portion 22a is formed through the weight 22, and a feed screw 23 is inserted through the internal thread portion 22a and meshed therewith.
In such a frequency adjustment mechanism 20, the weight 22 moves in the longitudinal direction Ds of the power generation element 11 along the rail 21 by rotating the feed screw 23 with the motor 24. As a result, the natural vibration frequency of the power generation element 11 is varied.

The frequency adjustment controller 25 that controls the operation of the frequency adjustment mechanism 20 is composed of a microcomputer (microcomputer), and operates by receiving power supplied from the power generation element 11 or the storage element 15.
The frequency adjustment controller 25 monitors the power generation amount (current value) in the power generation element 11, operates the motor 24 according to the detected power generation amount, and adjusts the position of the weight 22. As a result, the frequency adjustment controller 25 automatically adjusts the natural vibration frequency of the power generation element 11 (resonance frequency associated with the rotation of the rotating shaft 1) by adjusting the position of the weight 22 in accordance with the amount of power generation in the power generation element 11. .

Hereinafter, the flow of the automatic adjustment process of the natural vibration frequency of the power generation element 11 in the frequency adjustment controller 25 will be described with reference to FIG. The following processing is automatically executed based on a computer program stored in advance in the frequency adjustment controller 25.
Here, in the state immediately after the assembly in which the power generation element 11 and the frequency adjustment mechanism 20 are mounted on the rotary shaft 1, no power is stored in the power storage element 15, and no power is supplied to the frequency adjustment controller 25. The automatic adjustment processing by the number adjustment controller 25 cannot be performed. Therefore, it is preferable that power is stored in advance in the power storage element 15 from an external power source in the assembly stage.

In the automatic adjustment processing of the natural vibration frequency of the power generating element 11, first, the operation (rotation) of the rotating shaft 1 is started (step S101).
Then, the power generation element 11 vibrates with the rotation of the rotating shaft 1, and thereby the power generation element 11 starts power generation.

In the frequency adjustment controller 25, the motor 24 is operated for a predetermined time, and the position of the weight 22 is moved by a fixed dimension to change the position (step S102). Then, the natural frequency of the power generation element 11 changes due to the movement of the position of the weight 22. In the power generation element 11 that vibrates in a state after the position adjustment of the weight 22 is performed, the power generation amount in the power generation element 11 also changes.
Next, the frequency adjustment controller 25 measures the magnitude of the output current from the power generation element 11 as the power generation amount of the power generation element 11 (step S103).
Then, the value of the power generation amount measured in step S102 is stored in a storage area such as a memory provided in the frequency adjustment controller 25.

  Thereafter, the above steps S102 to S103 are repeated over the entire range in which the weight 22 is movable, and the output current from the power generating element 11 is measured at each position while moving the weight 22 by a certain size.

After the measurement of the output current from the power generation element 11 over the entire movable range of the weight 22 is completed, the motor 24 is operated, and the output current from the power generation element 11 stored in step S104 is stored in the weight 22. Move to the highest position. After the weight 22 is moved, the rotation of the motor 24 is stopped (step S104).
Thereby, the weight 22 can be arranged at a position where the power generation amount in the power generation element 11 is maximized, and the natural frequency of the power generation element 11 including the frequency adjusting mechanism 20 matches the natural frequency of the rotating shaft or It can be in a close state.

  Then, after a predetermined time has elapsed, the automatic position adjustment of the weight 22 in steps S102 to S104 is repeated (step S105).

  As described above, by automatically adjusting the position of the weight 22, the power generation amount in the power generation element 11 is maximized according to the number of rotations of the rotating shaft 1 (vibration generated on the rotating shaft 1) as a measurement target. It can be in a certain state. As a result, the power generation efficiency of the power generation element 11 can be maintained high without taking time for adjustment.

(Modification of the embodiment)
Next, a modified example of the embodiment of the power generation device and the detection system according to the present invention will be described. That is, in the above embodiment, the frequency adjustment controller 25 automatically adjusts the position of the weight 22 so that the power generation amount of the power generation element 11 is maximized. By the control as shown, the position of the cone 22 can be determined more accurately.
That is, as shown in FIG. 5, first, the rotating shaft 1 is actuated (rotated) (step S201). Then, the power generation element 11 vibrates with the rotation of the rotary shaft 1, thereby starting power generation.

In the frequency adjustment controller 25, the motor 24 is operated for a predetermined time, and the position of the weight 22 is moved by a fixed dimension to change the position (step S202). Then, the natural frequency of the power generation element 11 changes due to the movement of the position of the weight 22. The power generation amount of the power generation element 11 that vibrates in the state after the position adjustment of the weight 22 also changes.
Next, the frequency adjustment controller 25 measures the magnitude of the output current as the power generation amount of the power generation element 11 (step S203).
Then, the value of the power generation amount measured in step S102 is stored in a storage area such as a memory provided in the frequency adjustment controller 25.

  Thereafter, the above steps S202 to S203 are repeated over the entire range in which the weight 22 is movable, and the output current from the power generating element 11 is measured at each position while moving the weight 22 by a certain size.

After the measurement of the output current from the power generation element 11 over the entire movable range of the weight 22 is completed, the motor 24 is rotated in the reverse direction so that the output current from the power generation element 11 stored in step S104 is Move in a direction approaching the position where the peak value Pi is reached. At this time, the magnitude of the output current from the power generation element 11 is monitored each time the weight 22 is moved by a certain range, as in steps S202 and S203. Then, the weight 22 is moved to a position where the output current exceeds the position where the peak value Pi reaches the peak value Pi and reaches K% of the peak value Pi (K is a predetermined number of, for example, 70 or more and less than 95) (step S204).
Then, since the weight 22 passes the position where the peak value Pi of the output current from the power generation element 11 passes, the motor 24 is rotated forward again, and the output current of the power generation element 11 is stored in step S104. The weight 22 is moved in a direction approaching the position where the output current of the current reaches the peak value Pi. At this time, the weight 22 may pass a position where the output current of the power generation element 11 becomes the peak value Pi due to overshoot of the motor 24 or the like. Therefore, until the weight 22 matches the position where the output current of the power generating element 11 reaches the peak value Pi, the above-described forward / reverse rotation of the motor 24 is repeated, and the output current of the power generating element 11 peaks at the position of the weight 22. It converges to a position where the value Pi is obtained.
At this time, each time the forward / reverse direction of the motor 24 is switched, the rotational speed of the motor 24 is decreased stepwise, or the distance over which the weight 22 is moved by driving the motor 24 once is decreased stepwise. Or, the driving time of the motor 24 may be shortened stepwise. Thereby, the position of the weight 22 can be quickly converged to the position where the output current of the power generating element 11 becomes the peak value Pi.

Then, when the weight 22 matches the position where the output current of the power generating element 11 reaches the peak value Pi, the rotation of the motor 24 is stopped (step S205).
Thereby, the weight 22 can be arrange | positioned in the position where the electric power generation amount in the electric power generation element 11 becomes more than a predetermined lower limit.

  Then, after a predetermined time T1 has elapsed, the automatic position adjustment of the weight 22 in steps S202 to S205 is repeated (step S206).

  In addition, the measurement of the output current of the power generation element 11 is performed every certain time T2 shorter than the certain time T1 (step S207). When the measured output current value becomes a predetermined lower limit L (for example, less than X% (X is, for example, 60 or more and less than K) with respect to the peak value P1 of the output current), a step The automatic position adjustment of the weight 22 in S202 to S206 is repeated (step S208).

According to the configuration described above, if the power generation amount in the power generation element 11 becomes too low, the position of the weight 22 is automatically adjusted to adjust the natural frequency of the power generation element 11 to increase the power generation amount. Can continue to maintain.
When the frequency of change of the natural frequency on the power generation element 11 or the rotating shaft 1 side is high, in the process flow shown in FIG. 4, the natural frequency changes before a predetermined time passes in step S105, and the power generation amount is greatly increased. May decrease. In that case, the power generation amount of the power generation element 11 is insufficient, and signal transmission from the wireless transmission circuit 14a and position adjustment of the weight 22 may not be performed. On the other hand, as described above, when the amount of power generation becomes low, the position adjustment of the weight 22 is automatically performed, so that power generation can always be stably performed.

(Other variations)
The power generation device and the detection system of the present invention are not limited to the above-described embodiment and modifications described with reference to the drawings, and various modifications can be considered within the technical scope thereof.
For example, the state quantity measured by the sensor element 13 is not limited to the rotational torque of the rotating shaft 1 but may be other, for example, temperature.
Furthermore, the power generation device can be configured by the power generation element 11, the weight 22, the motor 24, and the frequency adjustment controller 25. The usage target of the power generated by the power generation apparatus is not limited to the transmission of data measured by the sensor element 13 and the signal transmission in the wireless transmission circuit 14a, but may be any other purpose.

  In addition, in the above-described embodiment, the configuration in which the power generation element 11 is attached to the rotating shaft 1 of the rotating machine is illustrated, but the rotating shaft 1 may be of any rotating machine. Furthermore, if the power generating element 11 vibrates, the vibration source to be attached is not limited to the rotating shaft 1 and may be any other device such as another device.

Moreover, although the electric power generation element 11 was made into the strip | belt-plate shape of a cross-sectional rectangle, this can also be made into the column shape of a cross-sectional circle. Also in this case, necessary power generation efficiency and sensor sensitivity can be obtained by making the cross-sectional secondary moment of the power generation element 11 sufficiently smaller than that of the rotating shaft 1. However, in the cylindrical power generation element 11, there is a possibility that the direction in which the vibration is generated is a cross section orthogonal to the central axis of the rotating shaft 1 and is not likely to be a linear reciprocating motion. Therefore, the cross-sectional shape of the power generating element 11 attached to the rotating shaft 1 is preferably a flat shape such as an elliptical shape or an elliptical shape in addition to the rectangular shape as in the above embodiment.
In addition to this, as long as it does not depart from the gist of the present invention, the configuration described in the above embodiment can be selected or changed to another configuration as appropriate.

1 Rotating shaft (vibration source)
DESCRIPTION OF SYMBOLS 10 Detection system 11 Electric power generation element 13 Sensor element (sensor)
14 Signal processor 14a Wireless transmission circuit (wireless transmitter)
14b Wireless transmission controller 15 Power storage element 20 Frequency adjusting mechanism 21 Rail 22 Weight 22a Female thread 23 Feed screw 24 Motor (moving means)
25 Frequency adjustment controller (measurement unit, control unit)

Claims (4)

A power generation element having one end connected to the vibration source and the other end being a free end, and generating power by vibration of the vibration source;
For the power generation element, a weight provided movably along the direction connecting the one end and the other end;
Moving means for moving the weight;
A measurement unit for measuring the output from the power generation element;
A control unit that controls the movement of the weight by the moving unit and adjusts the natural frequency of the power generating element according to the output level of the power generating element measured by the measuring unit;
A power generation device comprising:   2. The power generation device according to claim 1, wherein the control unit fixes the weight at a position where an output level of the power generation element reaches a peak when the weight is moved by the moving unit. .   The power generation apparatus according to claim 1, wherein the control unit moves the weight when an output of the power generation element measured by the measurement unit falls below a predetermined lower limit. A power generation device according to any one of claims 1 to 3,
A sensor that is attached to the power generation element or the vibration source and detects a state quantity;
A wireless transmitter that receives power from the power generation element and transmits a detection signal of the sensor to the outside;
A detection system comprising:

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