JPH04144819A - Oscillating type transportation device - Google Patents

Abstract

PURPOSE:To provide complete transportation with resonance frequency and make speed regular at the time of load change by adjusting voltage so that electric power value of an inverter for resonance generating source may coincide with an electric power reference value, and correcting voltage periodically according to the adjusted voltage amount to search for the resonance frequency. CONSTITUTION:When voltage correcting motion switching switch 29 and an operation switch not illustrated here are turned on, a microcomputer 20 initializes exciting frequency and computes output electric power of an inverter 19. When a computing electric power value becomes larger than a threshold, the exciting frequency is returned to a prescribed value, electric power computation is carried out from the frequency again, and the computed value is compared with the preset electric power value. When a computed electric power value is less than the preset value, the frequency is corrected to be increased, and the electric power is computed again. It is repeated until a computed value exceeds the preset value. Frequency where a computed value exceeds the preset value is set at resonance frequency, and comparison is repeated in the same manner thereafter.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a vibrating conveyance device controlled to perform conveyance operation at a resonant frequency.

(Prior Art) Conventionally, as a vibrating conveyance device, in addition to one in which the vibration generation source is constituted by an electromagnet, there is also one in which a piezoelectric element is used.

In any of these vibratory conveyance devices, in order to maximize conveyance efficiency, it is necessary to match the excitation frequency to the resonance frequency. From this point of view, a conveyor device with an excitation frequency adjustment function was developed, and it was published in Japanese Patent Laid-Open No. 62-21
This method is publicly known in Japanese Patent No. 8308. This is a CR with a potentiometer for adjusting the excitation frequency.
A type sine wave generator is installed, and by operating the potentiometer, the excitation frequency is gradually changed, and the worker observes the vibration state and sound changes with his or her own eyes and ears. It is designed to find the frequency.

(Problems to be Solved by the Invention) In the conventional configuration described above, adjustment to match the excitation frequency to the resonant frequency relies on the human five senses, so even an expert cannot easily make accurate adjustment, and adjustment variations inevitably occur. This results in an unavoidable drop in conveyance efficiency.

Moreover, the permissible range of excitation frequency is ±0.0 of the resonant frequency.
It has been experimentally confirmed that this resonant frequency is 2Hz, but since this resonant frequency has a negative temperature dependence, if the ambient temperature is changed from 0°C to 40°C, the resonant frequency will decrease to 2Hz.
will also decrease.

The reason for this is thought to be that the elastic modulus changes due to thermal expansion of the vibration system.

On the other hand, since the capacitor of the CR oscillator for adjusting the excitation frequency has a positive temperature dependence, the output frequency of this CR oscillator is such that the excitation frequency is 2Hz when the ambient temperature changes from 0℃ to 40℃. will also increase.

In this way, the temperature gradients of the temperature dependence on the vibration system and the CR oscillator side are opposite, so even if the excitation frequency is exactly matched to the resonant frequency at 20°C, the ambient temperature will be ±5 If the temperature changes by ℃, the deviation width between the excitation frequency and the resonant frequency will be approximately 0.5Hz, which is within the allowable range (0.2Hz).
Hz). This means that the excitation frequency needs to be adjusted even if the ambient temperature changes slightly, but as mentioned above, relying on the five human senses to make this adjustment would be troublesome. In addition, adjustment variations occur, which inevitably leads to a decrease in conveyance efficiency.

Also, the quantity (load) of conveyed parts on the conveyor during conveyance operation.
When this changes, the vibration amplitude of the conveying body changes accordingly, and the conveying speed fluctuates. Therefore, in order to stabilize the conveyance speed, it is necessary to adjust the input terminal to the vibration source according to changes in the load, but it is extremely difficult to manually adjust the voltage.

The present invention has been made in consideration of the above-mentioned circumstances, and therefore, its purpose is to automate the adjustment of the excitation frequency to the resonant frequency, and to easily and reliably transport the material at the best excitation frequency (resonance frequency). It is an object of the present invention to provide a vibrating conveyance device that can be operated, can cope with load fluctuations, and can always be operated at a constant conveyance speed.

[Configuration of the Invention (Means for Solving the Problems)] The vibration type conveyance device of the present invention is one that conveys a conveyed object by vibrating a conveyance body by applying an alternating current voltage to a vibration generation source. An inverter that applies an alternating current voltage to a generation source, a power calculation means that calculates the input power or output power of the inverter, and a frequency change means that changes the output frequency of the inverter, and the power calculated by the power calculation means. a resonant frequency search operation for determining a resonant frequency by adjusting the output frequency of the inverter by the frequency changing means so that the output frequency is maximized; A constant power control operation that adjusts the input voltage or output voltage of the inverter and a voltage correction operation that corrects the voltage according to the voltage adjustment amount adjusted by this constant power control operation are periodically repeated. .

(Function) As shown in Fig. 7, the change curve of vibration acceleration and the change curve of electric power with respect to excitation frequency are similar to each other,
The frequency of the peak value of vibration acceleration and the frequency of the peak value of electric power match. Therefore, if you find the frequency where the power is maximum, that point will be the resonant frequency.

The present invention focuses on such a relationship, and after the start of conveyance operation, first, the output frequency of the inverter is adjusted by the frequency change means so that the power value calculated by the power calculation means is maximized, and the resonance frequency is determined. Performs resonance frequency search operation.

During this resonance frequency search operation, if the weight of the conveyed object increases from, for example, 0 kg to 1 kg, it changes from the state of point A to the state of point B in Fig. 9, and both the vibration acceleration and the electric power decrease. , the conveyance speed will decrease. Therefore, after the resonant frequency search operation is completed, the power constant control operation is executed. In this constant power control operation, by adjusting the voltage, the state is changed from point B to point 0 in FIG. 9, and the power is made to match the value at point A. As a result, although the vibration acceleration recovers to some extent, there is still a difference in vibration acceleration between the 0 point and the A point by ΔG. Therefore, after the constant power control operation is completed, the voltage correction operation is performed. In this voltage correction operation, the voltage is corrected according to the voltage adjustment amount adjusted by the constant power control operation, thereby correcting the power and restoring the vibration acceleration to approximately the same level as point A. By periodically repeating each of the above operations, the vibration acceleration (conveying speed) is stabilized while adjusting the excitation frequency to the resonance frequency.

(Example) Hereinafter, an example in which the present invention is applied to a bowl-shaped parts feeder will be described based on the drawings.

First, in FIG. 2 showing the overall mechanical structure, 1
is a base formed in the shape of a disk, and on the upper surface of the base, a plurality of bimorphs 2 are arranged in an inclined manner at equal intervals on the same circumference. Each bimorph 2 is constructed by pasting a piezoelectric element 4, which is a vibration generation source, on both sides of a leaf spring 3, and a bowl-shaped carrier 6 is connected to the upper end of each leaf spring 3 via a vibration amplification spring 5. There is. In this case, each bimorph 2 is driven by a drive device 7, which will be described later, to apply an alternating current voltage to both piezoelectric elements 4 so that the polarization directions are opposite to each other. 6 is vibrated in a spiral direction (diagonally up and down in the circumferential direction), and the internal conveyance parts are conveyed along the spiral conveyance path 8.

Next, the configuration of the drive device 7 will be explained based on FIG. 1.

9 is AClooV or 200V commercial single-phase AC power supply,
Power is supplied from this power source 9 to a rectifier 11 via a line filter 10 for noise removal. This rectifier 10 is configured with a single-phase bridge full-wave rectifier circuit, and a DC voltage that has been full-wave rectified here is applied to a DC/DC converter 12.

This DC/DC converter 12 is composed of an RCC type or a flyback transformer type converter, and boosts a full-wave rectified DC voltage to a high-voltage DC voltage of 700V. Three output lines 13a of this DC/DC converter 12,
Resistors 14a, 14b and capacitors 15a, 15b are connected in parallel between 13b, 13c, thereby dividing the high voltage DC voltage of 700v into two power supplies of +350v and -350v.

On the other hand, the central output line 1 of the DC/DC converter 12
3b, the piezoelectric element 4 of the bimorph 2 and a short-circuit current prevention glue handle 16 are connected in series, and between this reactor 16 and the output lines 13a and 13c on both sides, a field effect transistor (hereinafter referred to as a switching element) is connected in series. F
The sources and drains of ETJ) 17a and 17b are connected. A gate signal is applied from the gate drive circuit 18 to the gates of both FETs 17a and 17b, whereby both FETs 17a and 17b are alternately turned on and off.
It is turned off and an alternating current voltage is applied to the piezoelectric element 4. During the positive half cycle of this AC voltage, one of the FETs 17a
At the same time, the other FET 17b is turned off,
Conversely, in the negative half cycle, the other FET 17b is P
The FET 17a is turned on using the WM method, and one of the FETs 17a is turned off.

An inverter 19 is constituted by these FETs 17a and 17b and the gate drive circuit 18. In this case, the gate drive circuit 18 receives the output signal of the output port P of the microcomputer 20 and the output signal of the output port P of the microcomputer 20.
The output signal of the PWM circuit 21 attached to the is input.

Then, according to the output signal of the PWM circuit 21, the piezoelectric element 4
The amplitude of the alternating current voltage applied to is controlled, and a polarity (+-) signal is output from the output port P. In this case, the period of the clock signal of the PWM circuit 20 is 0.8 microseconds,
If the width is 127, it is 0.8 x 127 - 101.6 [microseconds], so P every 101.6 microseconds (every 9.84 KHz)
WM control is possible. Therefore, in this embodiment, the microcomputer 20 outputs sinusoidal data to the PWM circuit 21 every 101.6 microseconds, outputs a polarity (+-) signal from the output port P, and outputs the AC applied voltage. control the amplitude and frequency of In this way, the microcomputer 20 also functions as a frequency changing means.

On the other hand, in order to detect the current value flowing through the piezoelectric element 4, D
A current transformer 22 is provided on the output line 13b of the C/DC converter 12, and the current is detected by the current transformer 22 and is connected to a resistor 23.
The current detection signal converted into a voltage value is input to the zero-cross detection interrupt circuit 24 of the microcomputer 20, and is also input to the A/D converter 26 of the microcomputer 20 via the rectifier 25. This A/D
The converter 26 is of a successive conversion type, has a conversion word length of 8 bits, and a conversion time of about 10 to 20 microseconds. Also,
The interrupt circuit 24 with zero cross detection is shown in FIG. 10(a).
When the level of the input signal changes from negative (-) to positive (+) or from positive (+) to negative (-) (crosses zero) as shown by il+j2+t3, the microcomputer 20 A pulse-like interrupt signal shown in FIG. 3(b) is input. The reason why the current detection signal is rectified through the rectifier 25 is because the A/D converter 26 is unipolar with no positive or negative polarity, and because it is necessary to use a negative polarity to calculate the effective value of the alternating current. This is because even if the calculation is performed by converting the polarity to positive polarity, the calculated value will be the same.

Also, in order to store the frequency and voltage value of the applied voltage just before the end of the previous transport operation as data, the battery
A random access read/write memory (hereinafter referred to as rRAMJ) 28 backed up by 7 is connected to the microcomputer 20 via a data bus.

On the other hand, at the input port I of the microcomputer 20,
A voltage correction operation changeover switch 29 is connected, and when this switch 29 is turned on, the voltage correction operation described below is executed, and when it is turned off, the voltage correction operation is omitted, and the resonant frequency search operation and constant power control operation, which will be described later, are performed. will only be executed. Further, in order to set a power reference value to be described later, a power reference value setting potentiometer 30 is provided, and this potentiometer 30 is connected to an A/D converter 31 of the microcomputer 20.

Note that a clock pulse is input from the oscillator 35 to this microcomputer 20, and based on this clock pulse, the microcomputer 20 outputs PWM to the PWM circuit 21.
It generates a WM signal and measures the phase difference between the applied voltage and current.

Next, the details of the operation control by the microcomputer 20 will be explained based on FIGS. 3 to 9.

When the voltage correction operation changeover switch 29 and the operation start switch (not shown) are turned on to start the conveyance operation, first,
A resonant frequency search operation is performed to match the excitation frequency to the resonant frequency.

The basic principle of this resonance frequency search operation will be explained based on FIG. 7. As shown in FIG. 7, the change curve of the vibration acceleration with respect to the excitation frequency and the change curve of the output power of the inverter 19 (power applied to the piezoelectric element 4) are similar to each other, and the peak value of the vibration acceleration The frequency and the frequency of the peak value of power match. From this relationship, if we find the frequency at which the power is maximum while changing the excitation frequency while keeping the output voltage of the inverter 19 (voltage applied to the piezoelectric element 4) constant, that point will be the resonant frequency. .

Using this relationship, in the resonant frequency search operation, the third
As shown in the figure, first, the excitation frequency f is set to an initial value f. (a frequency lower than the resonance frequency fr) (step P1), and the output power W of the inverter 19 is calculated (step P2). This calculation is based on the output voltage of the inverter 19 (
This is performed using the following equation (1) from the effective value VrllS of the voltage applied to the piezoelectric element 4 and the effective current value Irsss power factor eO5φ.

W-Vrls X I rms X cosφ --
--= (1) In this case, since the output voltage is adjusted by the PWM circuit 21 of the microcomputer 20, the effective value V rms of the applied voltage is set by the microcomputer 20 without measuring it with a voltmeter or the like. be done. Therefore, in this embodiment, the microcomputer 20
Although this function also serves as a means for determining the effective value Vr*S of the output voltage, it is also possible to have a configuration in which the effective value v rats of the output voltage is actually measured and determined using a separately provided voltmeter or the like.

The procedure for determining the effective current value I rss is to convert the current value flowing through the piezoelectric element 4 at a predetermined sampling period (50 to 200 μs) into the current transformer 22, resistor 23, rectifier 25, and A/D converter 26. The microcomputer 20 squares the sampling data, adds it for a specified cycle (N times), divides the added value by N, and squares the divided value to obtain the effective current value I rffls.
demand. Furthermore, the procedure for determining the power factor eO5φ involves detecting the zero-crossing timing tv of the output voltage and also detecting the zero-crossing timing t of the input current measured through the interrupt circuit 24 with zero-crossing detection. Then, the time difference 1tv t+l between the zero-crossing timing tv of these output voltages and the zero-crossing timing t of the current is calculated, and it is converted into a phase difference φ to calculate the power factor COSφ. In addition, as another method for calculating the power factor cosφ from the phase difference φ, the calculated value of COSφ with respect to φ is stored in a table in advance in the read-only memory (ROM) of the microcomputer 20, and COSφ is calculated from the stored data group. You may also read it.

The output power W is calculated from the voltage effective value V rls and the current effective value l rms s power factor cosφ obtained in this way using the above equation (1). In this embodiment, in order to improve the calculation accuracy, the calculation of the output power W is repeated several times and the average value is used as the power value.

After this, the power value W becomes the threshold value W. (See FIG. 8) It is determined whether it is larger than (step P3).

Here, the threshold value W. represents the boundary line of the region where the excitation frequency deviates significantly from the resonant frequency. Then, the power value W is a threshold value W. If it is below, the excitation frequency f is increased by Δf (step P4), and the power is calculated again (step P2) and the threshold W is determined. The comparison with (step P3) is repeated. In this example, Δfc is set to a thick value (
For example, the resonant frequency is set to 5 Hz) to shorten the search time for the resonant frequency after the power is turned on.

Then, the power value W is the threshold value W. When the excitation frequency exceeds f1, the excitation frequency is returned to, for example, 10 Hz (step P5), and the power calculation is performed again from the frequency f1 (step P6).

Then, this power value W is compared with a preset Wwax (step P7), and if the power value W is equal to or less than Wa+ax, the excitation frequency f is increased by Δf+ (for example, 0.1Hz or 0.2Hz) (step P7). P8), power calculation (step P6) and comparison with Wsax again (step P
Repeat 7). After this, if the power value W becomes larger than WIlax, the power value W at that time is set to Wmax, and the excitation frequency f at that time is set to the temporary resonance frequency f.
ri (step P10). After this, the excitation frequency f is increased by Δf, and the power calculation and comparison with WllaX are repeated. Then, when the excitation frequency f exceeds f, +20 Hz, the initial resonance frequency search operation after power-on is terminated (step P9, pH), and thereafter, steady operation is started.

The resonance frequency search operation during steady operation is executed according to the flowchart shown in FIG. First, after calculating the power value W1 using the temporary resonant frequency fri found in the initial resonant frequency search operation after the power is turned on (step P12), the excitation frequency f is increased by Δf (step P13). Calculate the power value W2 again (step P1
4).

Then, compare this W2 with Wl (step P15),
If W2 is less than or equal to W1, repeat the above steps again. As a result, the excitation frequency f is gradually brought closer to the true resonance frequency fr (the power value is gradually increased).

After this, when W2 exceeds Wl (when the excitation frequency f exceeds the resonance frequency fr), the excitation frequency f is decreased by Δf (step P16), and the power value W1 is calculated (step P17). Furthermore, the excitation frequency f is decreased by Δft (step P18), and the power value W2 is calculated (step P19). Then, this W2 is compared with Wl (step P20), and if W2 is larger than Wl, the power calculation is repeated again. As a result, the excitation frequency f is returned to approach the resonant frequency fr, and when W2 becomes W or less, the excitation frequency f at that time is set to the resonant frequency fr (step P21), and a resonant frequency search operation is performed. (Step P22).

During this resonance frequency search operation, if the weight of the conveyed object increases from, for example, 0 kg to 1 kg, it changes from the state of point A to the state of point B in Fig. 9, and both the vibration acceleration and the electric power decrease. , the conveyance speed will decrease. Therefore, after the resonant frequency search operation is completed, the power constant control operation shown in FIG. 5 is executed.

In this power constant control operation, as will be described later, by adjusting the voltage, the state is changed from point B to point 0 in FIG. 9, and the power is made to match the value at point A.

As a result, although the vibration acceleration recovers to some extent, there is still a difference in vibration acceleration between the 0 point and the A point by ΔG. Therefore, after the constant power control operation is completed, the voltage correction operation shown in FIG. 6 is executed. In this voltage correction operation, the voltage is corrected as described later in accordance with the voltage adjustment amount adjusted by the constant power control operation, thereby correcting the power and restoring the vibration acceleration to approximately the same level as point A. . By periodically repeating each of the above operations, the vibration acceleration (conveying speed) is stabilized while adjusting the excitation frequency to the resonance frequency.

In the constant power control operation executed after the end of the resonant frequency search operation described above, first, the inverter 19 at the time of the start is
The output voltage vo of is stored (step P23), and the power value W is calculated (step P24). Then, this power value W is compared with a power reference value Ws, which will be described later, in step P30.
), if the power value W is smaller than the power reference value Ws, the voltage V is increased according to the following equation (2), and if it is larger than the power reference value Ws, the voltage is lowered (step P31).

Vnev=VX・・・・・・
(2) By repeating the above operations until the power value W matches the power reference value Ws, the power is stabilized.

In this case, the power reference value is a true power reference value Ws given by the power reference value setting potentiometer 30, and a low power reference value Ws given after a voltage correction operation to be described later.
Normally, the low power reference value Wsi is used as the power reference value Ws (step P29), but in the following cases, the true power reference value Ws is used (step P28).

■At the time of the first cycle and at the second cycle after the start of steady operation (step P25) ■At the time of the first cycle and 2 after changing the value of the power reference value setting potentiometer 30 (true power reference value Ws) At the time of the first cycle (Step P) When the power value W is equal to the true power reference value Ws and the voltage value V is approximately equal to Vf (Step P2, vr is This is the output voltage of the inverter 19 at the end of the constant power control operation.

The reason why the true power reference value Ws is used in the case of (■) is that there is no low power reference value Wsi yet, and in the case of (■),
Low power reference value Ws because the true power reference value Ws has changed
This is because i has become meaningless, and in the case of ■, the error that accumulates by repeatedly correcting the low power reference value Wsl is reset when the state is the same as the initial setting (certain two If each power value and voltage value are equal for the operating state, the vibration acceleration and the weight of the transported object are both equal). In the case of (2), the voltage value does not necessarily have to completely match Vf, but only needs to be a close value.

When the power value W matches the power reference value Ws by such power constant control operation, the voltage value V at that time is stored as Vn (step P32), and the first or true power reference value is changed after the start of steady operation. If it is the next cycle (step P33), the voltage value V is set to vr (step P34), and the process returns to the resonant frequency search operation shown in FIG. In this way, the reason why the voltage correction operation is passed and the resonant frequency search operation is returned to at the first cycle after the start of steady operation and at the first cycle after changing the true power reference value is that in these cases, This is because the difference between vo and Vn does not depend only on an increase or decrease in the amount of transported objects.

On the other hand, if the determination in step P33 is negative (No), the process moves to the voltage correction operation shown in FIG. In this voltage correction operation, first, the voltage value Vn at the end of the constant power operation and the voltage value V before the start. ΔV (voltage adjustment amount) is calculated (step P35). If this voltage difference ΔV has a positive value, it means that the weight of the transported object has increased, and conversely, if it has a negative value, it means that the weight of the transported object has decreased. Then, based on this voltage difference ΔV, a new voltage value v new is calculated according to the following equation (3) (step P36).

Vnew −V+AxΔV −·····−(3) Here, A is a constant determined through experiments or the like. The reason for performing such voltage correction is that the larger the voltage difference Δ■, the larger the amount of variation in the conveyed object and the greater the variation in vibration acceleration. , which attempts to stabilize vibration acceleration.

After correcting the voltage value using the above equation (3), calculate the power value W (step P37), set the power value w as the temporary power reference value Wsi (step P38), and perform the resonant frequency search operation shown in FIG. Return to After that, the resonance frequency search operation,
Constant power control operation and voltage correction operation are repeated periodically.

In this case, even if the resonant frequency of the transport device fluctuates due to changes in ambient temperature or increases or decreases in the transported object, the excitation frequency can always be made to match the resonant frequency by the resonant frequency search operation performed periodically. Transport operation can be carried out most efficiently.

In addition, fluctuations in the vibration acceleration due to increases and decreases in the transported object can be effectively suppressed by the constant power control operation and the voltage correction operation, thereby stabilizing the vibration acceleration (transportation speed).

In addition, in cases where the amount of conveyed objects does not increase or decrease significantly during conveyance operation (for example, in a linear feeder, etc.), ΔG (
Since there is almost no variation in vibration acceleration) and there is no need for voltage correction operation, the voltage correction operation changeover switch 29 is turned off in order to speed up the other two control cycle times.

By the way, in the above embodiment, the output power of the inverter 19 (voltage applied to the piezoelectric element 4) during the resonance frequency search operation
Although the input power of one inverter is controlled to be maximized, the resonant frequency may be determined by controlling to maximize the input power of one inverter. This is because when the input power of the inverter 19 is maximized, the output power is also maximized. In addition, in order to maximize the input power of the inverter 19 during the resonance frequency search operation, the input voltage of the inverter 19 is adjusted so that the input power matches the power reference value during the constant power control operation, and the input voltage is It may be corrected by a correction operation.

In addition, the present invention is not limited to the bowl-shaped parts feeder as in the above embodiment, but can also be applied to linear parts feeders, and is not limited to those using a piezoelectric element as a drive source, but uses an electromagnet as a drive source. Various modifications are possible, such as being applicable to things that do.

[Effects of the Invention] As is clear from the above description, the present invention includes a resonant frequency search operation for determining the resonant frequency by adjusting the output frequency of the inverter so that the power value is maximized, and a resonant frequency search operation that determines the resonant frequency so that the power value is equal to the power reference value. The constant power control operation that adjusts the voltage to match the voltage and the voltage correction operation that corrects the voltage according to the amount of voltage adjustment adjusted by this constant power control operation are periodically repeated, so the ambient temperature Even if the resonant frequency of the conveying device fluctuates due to changes in the conveyance frequency or increase or decrease of conveyed objects, the excitation frequency can always be made to match the resonant frequency.
In addition to being able to carry out the most efficient conveyance operation, it also effectively suppresses fluctuations in vibration acceleration due to increases and decreases in conveyed objects, and has the excellent effect of stabilizing vibration acceleration. .

[Brief explanation of drawings]

The drawings show an embodiment of the present invention. Fig. 1 is a circuit diagram showing the overall electrical configuration, Fig. 2 is an external perspective view of the transport device, and Fig. 3 shows the initial resonance frequency after power is turned on. FIG. 4 is a flowchart showing the contents of the search operation. FIG. 4 is a flowchart showing the contents of the resonance frequency search operation during steady operation.
The figure is a flowchart showing the contents of the power-constant control operation, Figure 6 is a flowchart showing the contents of the voltage correction operation, and Figure 7 is a flowchart showing the contents of the voltage correction operation.
The figure shows the relationship between excitation frequency and electric power, vibration acceleration, current, and phase difference. Figure 8 shows the relationship between excitation frequency and electric power. Figure 9 shows the relationship between excitation frequency and electric power. FIG. 3 is a diagram for explaining how vibration acceleration changes. In the drawing, 2 is a bimorph, 3 is a leaf spring, and 4 is a piezoelectric element (
(vibration generation source), 6 is a bowl-shaped conveyor, 7 is a drive device, 1
2 is a DC/DC converter, 17a and 17b are FETs
, 18 is a gate drive circuit, 19 is an inverter, 20 is a microcomputer (power calculation means, frequency change means)
, 21 is a PWM circuit, 28 is a RAM, 29 is a voltage correction operation changeover switch, and 30 is a potentiometer for setting a power reference value. Agent Patent Attorney Sato

Claims (1)

[Claims] 1. In a vibrating conveyance device that conveys a conveyed object by vibrating a conveyance body by applying an AC voltage to a vibration generation source, an inverter that applies an AC voltage to the vibration generation source;
The frequency changing means includes a power calculating means for calculating input power or output power of the inverter, and a frequency changing means for changing the output frequency of the inverter, and the frequency changing means adjusts the power value calculated by the power calculating means to a maximum. a resonant frequency search operation for determining a resonant frequency by adjusting the output frequency of the inverter, and a power for adjusting the input voltage or output voltage of the inverter so that the power value calculated by the power calculation means matches a power reference value. A vibrating conveyance device characterized in that a constant control operation and a voltage correction operation for correcting the voltage according to the voltage adjustment amount adjusted by the constant power control operation are periodically repeated.