JP2012024082A - Spray device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spray device having improved chemical spraying efficiency by applying sufficient electric charge to the chemical and attaching a sufficient amount of the chemical even to closely spaced crops and distant crops.SOLUTION: A saw-tooth electric wave having large variation rate of voltage with time is applied to an electrode 4 to charge a liquid (e.g. chemical liquid) sprayed from a nozzle 20 in the form of mist with electric charge sufficient for attaching the liquid to closely spaced crops and distant crops, thereby coating the surface of the closely spaced crops and distant crops with the chemical to improve spraying efficiency of the chemical and surely exterminate insect pest. Furthermore, the variation rate of voltage with time is increased to improve the charge quantity of the sprayed chemical by converting a definite DC voltage to a pulse voltage and converting the voltage wave form to a saw-tooth wave.

Description

  The present invention relates to a spray device that sprays a liquid (for example, a chemical solution) in a mist form.

  When damage caused by pests, so-called worm-eating, occurs in the crops growing in the field, the commercial value of the crops is greatly reduced. Therefore, chemicals are sprayed on the crops to eliminate the pests. The crops are broadly divided into flat crops that grow so as to cover the surface of fields such as watermelon, strawberry, cabbage, leek and rice, and three-dimensional crops that grow and grow upward such as cucumber, tomato and eggplant. In general, the chemical solution is sprayed on the lower surface of a cylindrical boom that extends to the left and right by a sprayer in which a plurality of spray nozzles that spray the liquid in a mist form are connected. In recent years, in order to reliably attach a chemical solution to a crop, a spreader further provided with a configuration that imparts an electric charge to the injected liquid is often used.

  Patent Document 1 discloses a nozzle boom through which a chemical solution pumped from a chemical solution tank flows, a plurality of spray nozzles connected to the nozzle boom, and an electrostatic force that faces the tip of the spray nozzle and imparts an electric charge. An electrostatic application spreader including an application electrode is described. The electrostatic application spreader applies a high voltage pulse having a pulsed waveform to the electrostatic application electrode. The chemical liquid tank is grounded, and a charge is applied to the ground potential liquid ejected from the spray nozzle by a high voltage pulse, and the liquid is attracted to the crop by the Coulomb force and adheres. In addition, the electrostatic application type spreader includes a step-up transformer that raises the voltage, and a part of the spray nozzle is used as an iron core of the step-up transformer to reduce the number of parts.

  On the other hand, spraying of a chemical solution to a three-dimensional crop is often performed by a sprayer in which a spray nozzle is connected to the tip of a pipe through which the liquid flows. For example, in Patent Document 2, a chemical solution pumped from a storage tank by a pump is used. A flow tube, a spray nozzle connected to one end of the spray tube, an annular electrode disposed around the spray nozzle, and a grip for gripping provided at the other end of the spray tube An electrostatic spraying device is described. In the electrostatic spraying device, a constant direct current high voltage is applied to the annular electrode, the electric charge is applied to the liquid ejected from the spray nozzle, and the liquid is attracted and adhered to the crop by Coulomb force.

Japanese Patent No. 3822777 JP 2007-222729 A

Flat crops, especially varieties that grow densely, such as leeks and rice, are densely packed near the root if the amount of charge of the solution is small when the solution is sprayed by an electrostatic application sprayer using a nozzle boom. There are cases where chemicals do not adhere sufficiently to the area and pest control is insufficient.
On the other hand, in the case of a three-dimensional crop, a large number of crops are grown in a row, and a plurality of rows of three-dimensional crops are often arranged in the field. When spraying a chemical using the electrostatic spraying device, the user holds the grip and sprays the chemical sprayed from the spray nozzle toward both sides while moving between the rows. At this time, when the amount of charge of the chemical solution is small, due to the Faraday cage effect, the chemical solution concentrates on the surface of the crop and the edge of the leaf in the row closest to the user on both sides of the user, and The chemical solution does not reach the line, and the spraying efficiency decreases.

By the way, the charge amount of the chemical solution depends on the magnitude of the current I flowing through the electrode, and the current I is proportional to the amount of time change of the voltage V applied to the electrode (I = α · dV / dt, α is a proportional constant. , T is time), it is presumed that the chemical solution is more easily charged when a pulse voltage is applied to the electrode than a constant DC voltage.
As described above, the electrostatic spraying device described in Patent Document 2 applies a constant DC voltage to the annular electrode, but the high voltage pulse is applied as in the electrostatic application spreader described in Patent Document 1. It is considered that the amount of charge of the chemical solution can be increased by applying. However, the high-voltage pulse in the electrostatic application type spreader described in Patent Document 1 has a semicircular shape, and the slope of the voltage V is gentle, that is, the amount of time change of the voltage V is small, and the charge amount of the chemical solution is sufficient. It is thought that it cannot be increased.

  The present invention has been made in view of such circumstances, and a sufficient amount of a chemical solution is provided to a dense portion of a flat crop and a row of three-dimensional crops located away from the user by imparting a sufficient charge to the chemical solution. It aims at providing the spraying device which can be made to adhere and can improve the spraying efficiency of a chemical | medical solution.

  A spraying device according to the present invention includes a nozzle having an injection port for injecting a liquid in a mist shape, an electrode disposed around the injection port, and applying an electric charge to the liquid injected from the injection port. A spraying device comprising a pulse voltage generating means for generating a pulse voltage to be applied, wherein the pulse voltage generating means generates a sawtooth wave.

  In the present invention, a sawtooth wave having a large amount of time variation is applied to the electrode, and the liquid sprayed in a mist form from the spraying port is given sufficient charge to adhere to the densely packed part of the crop and to the distant crop. To do.

  The spray device according to the present invention is characterized in that the pulse voltage generating means is a DC-DC converter.

  In the present invention, a constant DC voltage (input voltage) is converted into a high-frequency pulse voltage, boosted by a transformer, and further smoothed to obtain a DC output voltage of a predetermined voltage. At this time, the input voltage is turned on and off at a predetermined frequency using a switch, thereby outputting a high voltage pulse voltage having a predetermined frequency.

  The spray device according to the present invention is characterized in that the frequency of the sawtooth wave is 100 hertz or less.

  In the present invention, the charge amount of the liquid ejected from the ejection port is maximized by controlling the voltage frequency to 100 hertz or less.

  In the spraying apparatus according to the present invention, a sawtooth wave having a large amount of time change is applied to the electrode, and a liquid (for example, a chemical solution) sprayed in a mist form from the spraying port has a dense crop portion and a distant crop. By applying a sufficient charge to adhere to the surface, the dense part of the crop and the surface of the distant crop are covered with a chemical solution, the spraying efficiency of the chemical solution is improved, and the pests can be reliably controlled.

  In the spray device according to the present invention, it is possible to convert a constant DC voltage into a pulse voltage and further smooth it to generate a sawtooth wave.

  In the spray device according to the present invention, a constant DC voltage (input voltage) is converted into a high-frequency pulse voltage, boosted by a transformer, and further smoothed to obtain a DC output voltage of a predetermined voltage. At this time, by turning on / off the input voltage at a predetermined frequency using a switch, a high-voltage pulse voltage having a predetermined frequency can be output to maximize the charge amount of the injected liquid medicine.

  In the spraying apparatus according to the present invention, by controlling the voltage frequency to 100 hertz or less, the charge amount of the chemical liquid sprayed from the spraying port is maximized, and the densely packed part of the crop and the surface of the distant crop Can be reliably coated with a chemical solution to improve the spraying efficiency of the chemical solution, and the pests can be reliably exterminated. As will be described later, compared to the case where a constant DC voltage is applied, the coverage area ratio in which the surface or back surface of the leaf is covered with the sprayed chemical solution is larger when a pulse voltage of 100 hertz or less is applied. On the other hand, when the frequency exceeds 100 Hz, the voltage rises and falls within a short time, a voltage with a large slope cannot be applied to the electrode for a long time, and the waveform becomes close to a constant direct current, It is not preferable.

It is sectional drawing which shows schematically the nozzle vicinity of the spraying apparatus which concerns on embodiment. FIG. 3 is a circuit diagram schematically showing a pulse generation circuit. 6 is a time chart schematically showing the relationship between the input voltage to the source of the FET, the input pulse voltage to the gate of the FET, and the output voltage of the smoothing circuit when the switch is turned on and off. 5 is a time chart schematically showing a pulse voltage applied to an electrode when a control signal related to a rectangular wave having a duty ratio of 0.1 and a frequency of 2 hertz (Hz) is output from a PG. 6 is a time chart schematically showing a pulse voltage applied to an electrode when a control signal related to a rectangular wave having a duty ratio of 0.1 and a frequency of 4 Hz is output from a PG. It is the schematic diagram which showed schematically the structure of the experimental apparatus for confirming an adhesion rate from upper direction. It is a figure which shows the surface and back surface of the water sensitive paper which the liquid adhered in the case of (A). It is a figure which shows the surface and back surface of the water sensitive paper which the liquid adhered in the case of (B). It is a figure which shows the surface and the back surface of the water sensitive paper to which the liquid adhered in the case of (C). It is a figure which shows the surface and back surface of the water sensitive paper which the liquid adhered in the case of (D). It is a figure which shows the surface and the back surface of the water sensitive paper to which the liquid adhered in the case of (E). It is a figure which shows the surface and the back surface of the water sensitive paper to which the liquid adhered in the case of (F). It is a figure which shows the surface and the back surface of the water sensitive paper to which the liquid adhered in the case of (R). FIG. 6 is a diagram schematically showing a relationship between a voltage applied to an electrode and a current flowing through a droplet by outputting from a PG a control signal related to a rectangular wave having a duty ratio of 0.1 and a frequency of 4 Hz. It is the schematic diagram which showed schematically the structure of the experimental apparatus for confirming the relationship between the shape of a voltage waveform, and the adhesion rate to the injection target of a chemical | medical solution from the upper direction. It is a figure which shows the relationship between the output voltage of PG, and the voltage applied to the nozzle. It is a graph which shows the adhesion area of the liquid per dummy tree.

Hereinafter, the present invention will be described in detail with reference to the drawings illustrating a spray device according to an embodiment. FIG. 1 is a cross-sectional view schematically showing the vicinity of a nozzle 2 of a spraying apparatus according to an embodiment.
In the figure, reference numeral 1 denotes a flow pipe through which a chemical liquid flows, and one end of the flow pipe 1 is connected to a tank (see FIG. 4 described later) that stores the chemical liquid. A cylindrical nozzle 2 having an injection port 20 for injecting a liquid in a mist form is connected to the other end of the flow pipe 1. The injection port 20 is located at the center of the tip surface of the nozzle 2. Around the nozzle 2, there is provided a cylindrical accommodating portion 3 that accommodates a high-voltage electric wire, which will be described later, and the nozzle 2 is coaxially disposed inside the accommodating portion 3. The cylindrical accommodating portion 3 is formed with an elongated bottomed cylindrical accommodating chamber 30 along the axial direction, and the opening of the accommodating chamber 30 is provided on the end surface of the accommodating chamber 30 on the flow tube 1 side. It is.

  The outer diameter of the end surface portion of the accommodating portion 3 on the side opposite to the flow pipe 1 is smaller than the outer diameter of other portions, and a step is formed. An annular electrode 4 is fitted in the stepped portion of the accommodating portion 3. A cylindrical waterproof member 51 is provided in the vicinity of the opening of the storage chamber 30 inside the storage chamber 30, and the high-voltage electric wire 5 is inserted in a watertight manner inside the waterproof member 51. The high voltage electric wire 5 is connected to the electrode 4. On the outer peripheral surface of the cylindrical accommodating portion 3, an annular recess 31 is formed in the middle in the axial direction, and an O-ring 50 is fitted in the recess 31.

  A cylindrical cover 6 that covers the electrode 4 is provided from the end surface of the accommodating portion 3 on the electrode 4 side to the concave portion 31. An annular groove 60 is formed on the inner peripheral surface of the cover 6 on the electrode 4 side, and an O-ring 50 is fitted in the groove 60. The side surface of the groove 60 on the electrode 4 side is open, and the O-ring 50 fitted in the groove 60 is adjacent to the end surface of the electrode 4. In a state where the O-rings 50 and 50 are sandwiched, the cover 6 is fitted in the accommodating portion 3 in a watertight manner. Therefore, the chemical solution does not enter from the gap between the cover 6 and the accommodating portion 3 and reach the electrode 4, thereby preventing leakage.

  FIG. 2 is a circuit diagram schematically showing the pulse voltage generation circuit 80. A pulse voltage generation circuit 80 is connected to the electrode 4 via the high voltage electric wire 5, and a high voltage pulse voltage is applied to the electrode 4 from the pulse voltage generation circuit 80.

  The pulse voltage generation circuit 80 is a DC-DC converter, and as shown in FIG. 2, a switch 87 is interposed between a positive electrode of a DC power supply 81 that is a battery and a source of a p-type FET 83. A primary coil 84 a of the step-up transformer 84 is interposed between the drain of the FET 83 and the negative electrode of the DC power supply 81. An oscillation circuit 82 is connected to the gate of the FET 83. The oscillation circuit 82 is supplied with electric power from a DC power supply 81 via a switch 87. When the switch 87 is turned on, the FET 83 is turned on and off at a constant high-frequency cycle by a signal input from the oscillation circuit 82 to the gate.

  One end of the primary coil 84a is connected to the drain of the FET 83, and the other end of the primary coil 84a and one end of the secondary coil 84b of the step-up transformer 84 are connected. One end of the secondary coil 84 b is connected to the electrode 4. The anode of the diode 85 is connected to the other end of the secondary coil 84b, and a smoothing circuit 86 is interposed between the cathode of the diode 85 and the electrode 4 or between one end of the secondary coil 84b and the electrode 4. It is. The smoothing circuit 86 includes a capacitor input type smoothing circuit, but other smoothing circuits such as an inductor or a choke input type smoothing circuit are used according to the specifications of the pulse voltage generation circuit 80 for generating a sawtooth wave. May be. The other end of the primary coil 84 a and one end of the secondary coil 84 b are connected to the negative electrode of the DC power supply 81.

The switch 87 is formed of a photocoupler. In the phototransistor of the switch 87, the collector is connected to the positive electrode of the DC power supply 81, and the emitter is connected to the source of the transmission circuit 82 and the FET 83. A pulse generator (hereinafter referred to as PG) 8 for generating a pulse signal for controlling on / off of the switch 87 is connected to the light emitting diode of the switch 87.
An optical pulse signal corresponding to the pulse signal generated in PG 8 is output from the light emitting diode. The phototransistor is turned on by receiving the light pulse signal.

  When the switch 87 is turned on, the positive voltage of the DC power supply 81 is applied to the source of the FET 83 and the transmission circuit 82. Thus, a high frequency pulse signal is input from the oscillation circuit 82 to the gate of the FET 83, and a high frequency pulse current flows through the primary coil 84a. Note that the frequency of the pulse signal input to the gate of the FET 83 is sufficiently higher than the frequency of the output pulse of PG8.

  By passing a high-frequency pulse current through the primary coil 84a, a high-frequency pulse current having a voltage higher than the voltage of the current passed through the primary coil 84a is generated in the secondary coil 84b. The current generated in the secondary coil 84 b is rectified by the diode 85. The voltage (pulse wave) related to the high-frequency pulse current is smoothed by the smoothing circuit 86 so as to gradually decrease after rising sharply, and a sawtooth wave is applied to the electrode 4.

  Next, the operation of the pulse generation circuit 80 will be described in detail. FIG. 3 is a time chart schematically showing the relationship between the input voltage to the source of the FET 83, the input pulse voltage to the gate of the FET 83, and the output voltage of the smoothing circuit 86 when the switch 87 is turned on and off.

  FIG. 3A shows the input voltage to the source of the FET 83 and corresponds to the output of PG8. FIG. 3B shows the input pulse voltage to the gate of the FET 83 and corresponds to the voltage applied to the primary coil 84a. FIG. 3C shows the output voltage of the smoothing circuit 86 and corresponds to the voltage applied to the electrode 4.

When the switch 87 is turned on at time t1 and the switch 87 is turned off at time t2 by the output pulse of PG8, a voltage is applied to the source of the FET 83 between times t1 and t2, as shown in FIG. 3A. On the other hand, as shown in FIG. 3B, a high-frequency pulse voltage is applied from the transmission circuit 82 to the gate of the FET 83.
Then, the smoothing circuit 86 is charged between the times t1 and t2, and as shown in FIG. 3C, the output voltage of the smoothing circuit 86 rises with a steep slope between the times t1 and t2. After the energization is completed, between times t2 and t3, the output voltage of the smoothing circuit 86 gradually decreases due to the discharge from the smoothing circuit 86, and a sawtooth wave is generated.

  Similarly, the sawtooth wave can be continuously generated by turning on the switch 87 at time t3 and repeating the above operation. In other words, the sawtooth wave can be continuously generated by turning on / off the switch 87 at an appropriate time interval by the output pulse of PG8.

  The pulse voltage applied to the electrode 4 has a time variation in voltage when the voltage rises larger than a time variation in voltage when the voltage falls. When the chemical liquid sprayed in the form of a mist from the injection port 20 passes through the inside of the annular electrode 4, the chemical liquid is charged and is attracted to and adhered to a target to be sprayed such as a crop by Coulomb force.

  An element that generates a sawtooth wave is a time constant determined by the circuit constant of the smoothing circuit 86, and the output waveform of the smoothing circuit 86 can be adjusted by adjusting the time constant. Further, a periodic pulse voltage applied to the electrode 4 can be generated by the output pulse of PG8. For example, by outputting from the PG8 a control signal related to a rectangular wave with a predetermined frequency having a predetermined duty ratio, the pulse voltage Adjust the frequency.

  FIG. 4 is a time chart schematically showing a pulse voltage applied to the electrode 4 when a control signal related to a rectangular wave having a duty ratio of 0.1 and a frequency of 2 hertz (Hz) is output from the PG 8. . The pulse voltage shown in FIG. 4 rises substantially vertically from a voltage of approximately 3.3 kilovolts (kV) to approximately 4.5 kV, and falls in an arc shape from the top of the rise to approximately 3.3 kV. The substantially vertical waveform portion and the arc-shaped waveform portion are continuous at the apex. In addition, the arcuate waveform portion has a curved line protruding toward the substantially vertical waveform portion side.

  FIG. 5 is a time chart schematically showing a pulse voltage applied to the electrode 4 when a control signal related to a rectangular wave having a duty ratio of 0.1 and a frequency of 4 Hz is output from the PG 8. The pulse voltage shown in FIG. 5 rises substantially vertically from a voltage of about 3 kV to about 4.5 kV, and falls in an arc shape from the top of the rise to about 3 kV, and has a substantially vertical waveform portion and an arc shape. The waveform portion forming is continuous at the apex. In addition, the arcuate waveform portion has a curved line protruding toward the substantially vertical waveform portion side.

  Next, the adhesion rate of the chemical solution injected from the injection port 20 of the spray device to the injection target will be described. FIG. 6 is a schematic diagram schematically showing the configuration of an experimental apparatus for confirming the adhesion rate from above.

  In the figure, I to VI indicate the positions of the water sensitive papers as if they were crop leaves, and the water sensitive papers are arranged at a height of 74 cm. Water sensitive papers I, III, and V are arranged in order along the jet direction of the nozzle 2 on one side with an extension line from the jet nozzle 20 of the nozzle 2 in the jet direction as a boundary. And a gap of 40 cm is provided between the water sensitive papers III and V. Further, water sensitive papers II, IV, VI are arranged along the ejection direction of the nozzle 2 on the other side with the extension line as a boundary, and between the water sensitive papers II and IV and the water sensitive papers IV and VI. A space of 40 cm is provided between them. Further, the water sensitive papers I and II, the water sensitive papers III and IV, and the water sensitive papers V and VI are opposed to each other with an interval of 20 cm.

  The nozzle 2 is located at a substantially middle point of a line segment connecting the water sensitive papers I and II in the direction in which the water sensitive papers I and II are opposed to each other, and is located at a distance of 20 cm from the middle point in the direction opposite to the ejection direction. Is arranged. The water sensitive paper faces the injection port 20 of the nozzle 2 and has a vertical dimension of 5.2 cm and a horizontal dimension of 7.6 cm. Hereinafter, the surface of the water-sensitive paper facing the ejection port 20 of the nozzle 2 is referred to as the front surface, and the surface opposite to the front surface is referred to as the back surface. The nozzle 2 is connected via a flow pipe 1 to a tank that stores a liquid corresponding to a chemical solution, and the tank is grounded. The hole diameter of the injection port 20 of the nozzle 2 is 1.0 mm, the pressure of the injected liquid is 1.0 MPa, and the flow rate of the liquid is 0.76 L / min. The liquid ejection time is 5 seconds.

  In the above experimental apparatus, (A) when a liquid is ejected without applying a voltage to the electrode 4, (B) when a liquid is ejected by applying a constant DC voltage of 4.5 kV to the electrode 4, (C) When a control signal related to a rectangular wave with a duty ratio of 0.1 and a frequency of 2 Hz is output from the PG 8 and a liquid is ejected by applying a voltage to the electrode 4 (see FIG. 4), (D) the duty ratio is 0 1. When a control signal related to a rectangular wave having a frequency of 4 Hz is output from PG 8 and a voltage is applied to the electrode 4 to eject a liquid (see FIG. 5), and (E) a constant DC voltage of 9 kV is applied to the electrode 4 Table 1 to Table 5 below show the coating area ratio of the liquid adhering to the front and back surfaces of the water-sensitive paper.

Tables 1 to 5 correspond to cases (A) to (E), respectively. I to VI described in the column of “water sensitive paper” in each table indicate water sensitive papers located at I to VI in FIG. 6. The “covered area ratio” column in the “front surface” indicates the ratio (percentage) of the area where the liquid adheres to the surface area of the water sensitive paper, and the “covered area ratio” column in the “back surface”. Shows the ratio of the area where the liquid adheres to the area of the back surface of the water sensitive paper. For the calculation of the covering area ratio, water sensitive paper covering area calculation software was used. In the “average value” column, the average of the coverage areas of the water-sensitive papers located in III to VI for both “front surface” and “back surface” is shown. An ink having a high light reflectance (for example, yellow) is coated on the surface of the water sensitive paper. The ink changes color when droplets adhere. For example, it turns blue. The software calculates the coverage area ratio by the ratio of the discolored portion in the entire surface.
Since the water sensitive papers located at I and II are close to the nozzle 2, a large amount of droplets adhere to the surface and the ink flows down, and the surface of the water sensitive paper becomes white. For this reason, the water sensitive paper covering area calculation software determines that the droplet should not be attached to a portion where it should be determined that the droplet is attached, and calculates a value lower than the original value. Therefore, it is considered that I and II may be regarded as a substantially 100% adhesion rate. Therefore, I and II were excluded in calculating the average value of “surface”. Also, I and II were excluded in calculating the average value of the “back surface” in order to achieve a flatness with the “front surface”.

  FIG. 7 is a diagram showing the front and back surfaces of the water-sensitive paper to which liquid has adhered in the case of (A), and FIG. 8 is a diagram showing the front and back surfaces of the water-sensitive paper to which liquid has adhered in the case of (B). FIG. 9 is a diagram showing the front and back surfaces of the water-sensitive paper to which liquid has adhered in the case of (C), and FIG. 10 is a diagram showing the front and back surfaces of the water-sensitive paper to which liquid has adhered in the case of (D). FIG. 11 is a diagram illustrating the front and back surfaces of the water-sensitive paper to which the liquid has adhered in the case of (E). In FIGS. 7 to 11, the darkly colored portion is the portion to which the liquid has adhered.

  As shown in Tables 1 to 5 and FIGS. 7 to 11, when the voltage is applied to the electrode 4 (B) to (E), compared to the case where the voltage is not applied to the electrode 4 (A). However, the coverage area ratio is large. The average coverage area ratio is (D)> (C)> (E)> (B)> (A) on the front surface, and (E)> (C)> (D)> (B)> on the back surface. (A). That is, when the pulse voltage is applied rather than the case where the constant DC voltage 4.5 kV is applied to the electrode 4 (B), that is, the control signal relating to the rectangular wave having the duty ratio of 0.1 and the frequency of 2 Hz is supplied to PG8. When a voltage is applied to the electrode 4 (C) and a control signal related to a rectangular wave with a duty ratio of 0.1 and a frequency of 4 Hz is output from the PG 8 and a voltage is applied to the electrode 4 (D ) Shows that the average coverage area ratio is larger on both the front and back surfaces.

  Moreover, when the average coverage area ratio on the surface in the case of (C) and (D) is compared, it becomes 92.96 (C) and 95.20 (D), and both exceed 90%. The average coverage area ratio on the back surface is 30.95 (C) and 19.84 (D), with (C) being larger. In addition, in the case of (A) to (D), the coverage area ratio of the surface at the positions (I) and (II) 20 cm from the nozzle 2 and the coverage area ratio of the surface at the position (I) in the case of (E) Is about 30% to 50%, but an adhesion rate of 90% or more (substantially 100%) is visually observed.

  The surface coverage ratio at the positions (III) and (IV) 60 cm from the nozzle 2 is 90% or more when (A) is not applied with voltage, and (B) to (E) when voltage is applied. It is about 90%, and no big difference is recognized. On the other hand, the surface coverage ratio at the position (VI) 100 cm from the nozzle 2 is 59.351 when the constant DC voltage 9 kV is applied to the electrode 4 (E), and the constant DC voltage 4 When a voltage of .5 kV is applied to the electrode 4, the coverage area ratio of (B) is 25.151, whereas when a pulse voltage having a peak value of approximately 4.5 kV is applied (C), the coverage area ratio of (D) Are 95.65 and 88.115, respectively. That is, the adhesion rate of (C) and (D) is approximately 1.5 times the adhesion rate of (E), and is approximately 3.5 times the adhesion rate of (B). This indicates that in the case of (B) and (E), the droplet reaching the position of 100 cm from the nozzle 2 is greatly reduced compared to the case of (C) and (D). It is considered that droplets can be adhered farther when a pulse voltage is applied than when a constant DC voltage is applied.

  Further, referring to the average coverage area ratio on the front and back surfaces of (B) to (D) and the coverage area ratio at the position (VI), a pulse voltage (2 Hz higher than that in (B) when applying a constant DC voltage ( C) and a pulse voltage (D) of 4 Hz are applied, the coverage area ratio is increased, and the coverage area ratio can be further improved.

  In the above experimental apparatus, the following experiment was performed by replacing the pulse generation circuit 80 with a high voltage amplifier (not shown). The high-voltage amplifier is a device that reads a waveform from PG 8 and generates a high voltage having substantially the same waveform. When a triangular wave (sawtooth wave) is output from the PG 8 to the high voltage amplifier, a voltage of a triangular wave (sawtooth wave) is applied to the electrode 4.

(F) When a constant DC voltage of 2.25 kV is applied to the electrode 4 to eject a liquid,
(G) When a control signal related to a triangular wave with a duty ratio of 0.1 and a frequency of 2 Hz is output from PG 8 and a voltage having a peak value of 2.25 kV is applied to the electrode 4 to eject a liquid,
(H) When a control signal related to a triangular wave with a duty ratio of 0.5 and a frequency of 2 Hz is output from PG 8 and a voltage having a peak value of 2.25 kV is applied to the electrode 4 to eject a liquid,
(I) When a control signal related to a triangular wave having a duty ratio of 0.1 and a frequency of 4 Hz is output from PG 8 and a voltage having a peak value of 2.25 kV is applied to the electrode 4 to eject a liquid,
(J) When a control signal related to a triangular wave with a duty ratio of 0.5 and a frequency of 4 Hz is output from PG 8 and a liquid having a peak value of 2.25 kV is applied to the electrode 4 to eject liquid,
(K) When a control signal related to a triangular wave having a duty ratio of 0.1 and a frequency of 10 Hz is output from PG 8 and a voltage having a peak value of 2.25 kV is applied to the electrode 4 to eject a liquid,
(L) When a control signal related to a triangular wave with a duty ratio of 0.5 and a frequency of 10 Hz is output from PG 8 and a voltage having a peak value of 2.25 kV is applied to the electrode 4 to eject a liquid,
(M) When a control signal related to a triangular wave with a duty ratio of 0.1 and a frequency of 20 Hz is output from PG 8 and a voltage having a peak value of 2.25 kV is applied to the electrode 4 to eject a liquid,
(N) When a control signal related to a triangular wave with a duty ratio of 0.5 and a frequency of 20 Hz is output from PG 8 and a voltage having a peak value of 2.25 kV is applied to the electrode 4 to eject a liquid,
(O) When a control signal related to a triangular wave with a duty ratio of 0.1 and a frequency of 50 Hz is output from PG 8 and a voltage having a peak value of 2.25 kV is applied to the electrode 4 to eject a liquid,
(P) When a control signal related to a triangular wave with a duty ratio of 0.5 and a frequency of 50 Hz is output from PG8, a voltage having a peak value of 2.25 kV is applied to the electrode 4, and liquid is ejected,
(Q) When a control signal related to a triangular wave with a duty ratio of 0.1 and a frequency of 100 Hz is output from PG 8 and a voltage having a peak value of 2.25 kV is applied to the electrode 4 to inject liquid, and (R) duty When a control signal related to a triangular wave having a ratio of 0.5 and a frequency of 100 Hz is output from PG 8 and a voltage of a peak value of 2.25 kV is applied to the electrode 4 to inject liquid, the front and back surfaces of the water sensitive paper Tables 6 to 18 below show the coating area ratio of the liquid adhering to the surface. Tables 6 to 18 correspond to cases (F) to (R), respectively.
In the “average value” column, the average of the coverage areas of the water-sensitive papers located in III to VI for both “front surface” and “back surface” is shown.

  Note that the pulse voltage in the cases (G) to (R) rises substantially vertically from a voltage of approximately 0 kV to approximately 2.25 kV, falls in an arc shape from the top of the rise to approximately 0 kV, and is approximately vertical. The waveform portion and the waveform portion forming an arc shape are continuous at the apex. In addition, the arcuate waveform portion has a curved line protruding toward the substantially vertical waveform portion side.

  FIG. 12 is a diagram illustrating the front and back surfaces of the water-sensitive paper to which liquid has adhered in the case of (F), and FIG. 13 is a diagram illustrating the front and back surfaces of the water-sensitive paper to which liquid has adhered in the case of (R). is there.

  As shown in Tables 6 to 18, when applying a pulse voltage of 2 to 100 Hz with a peak value of 2.25 kV as compared to the case of applying a constant DC voltage of 2.25 kV (F) (G) to ( R) has a higher average surface area coverage. In the case of (F), it is 54.2%. On the other hand, 61.3% for (G), 66.4% for (H), 59.7% for (I), 60.5% for (J), 56.0% for (K). (L) 56.0%, (M) 58.6%, (N) 56.2%, (O) 63.5%, (P) 60.0% (Q) is 58.2%, and (R) is 64.6%. Therefore, when a pulse voltage is applied, it is about 1.8 to 12% larger than when a DC voltage is applied.

  Moreover, the average coverage area ratio of the surface at the position (V) 100 cm from the nozzle 2 is 62.3% in the case of (F). On the other hand, in the case of (G), it is 88.6, which is approximately 1.4 times that of (F). In the case of (H), it is 73.3%, which is approximately 1.2 times that of (F). In the case of (I), it is 74.0%, which is approximately 1.2 times that of (F). In the case of (L), it is 74.8%, which is approximately 1.2 times that of (F). In the case of (M), it is 82.7%, which is approximately 1.3 times that of (F). In the case of (N), it is 82.5%, which is about 1.3 times that of (F). In the case of (O), it is 72.4%, which is about 1.2 times that of (F). In the case of (Q), it is 77.4%, which is approximately 1.2 times that of (F). In the case of (R), it is 93.3%, which is about 1.5 times that of (F).

  Moreover, the average coverage area ratio of the surface at the position (VI) 100 cm from the nozzle 2 is 5.1% in the case of (F). On the other hand, in the case of (H), it is 37.0%, which is approximately 7.3 times that of (F). In the case of (I) and (J), it is 37.6%, which is approximately 7.4 times that of (F). In the case of (K), it is 37.3%, which is approximately 7.3 times that of (F). In the case of (L), it is 26.1%, which is approximately 5.1 times that of (F). In the case of (M), it is 19.0%, which is approximately 3.7 times that of (F). In the case of (N), it is 21.9%, which is approximately 4.3 times that of (F). In the case of (O), it is 15.8%, which is approximately 3.1 times of (F). In the case of (P), it is 32.2%, which is approximately 6.3 times that of (F). The field of (Q) is 18.8%, which is approximately 3.7 times of (F). In the case of (R), it is 11.6%, which is about 2.3 times that of (F).

  Further, the average coverage area of the back surface at the position (V) 100 cm from the nozzle 2 is 7.2% in the case of (F). On the other hand, in the case of (H), it is 29.0%, which is about four times that of (F). In the case of (I), it is 33.8%, which is approximately 4.7 times that of (F). In the case of (J), it is 32.2%, which is approximately 4.5 times that of (F). In the case of (K), it is 31.9%, which is approximately 4.4 times that of (F). In the case of (L), it is 26.2%, which is approximately 3.6 times that of (F). In the case of (M), it is 20.9%, which is approximately 2.9 times that of (F). In the case of (N), it is 17.4%, which is approximately 2.4 times that of (F). In the case of (O), it is 18.6%, which is approximately 2.6 times that of (F). In the case of (P), it is 13.6%, which is approximately 1.9 times of (F). In the case of (Q), it is 15.9%, which is approximately 2.2 times that of (F). In the case of (R), it is 14.7%, which is approximately twice that of (F).

  Moreover, the average covered area ratio of the back surface at the position (VI) 100 cm from the nozzle 2 is 1.3% in the case of (F). On the other hand, in the case of (H), it is 27.5%, which is about 21.2 times of (F). In the case of (I), it is 33.0%, which is approximately 25.4 times that of (F). In the case of (J), it is 31.6%, which is approximately 24.3 times that of (F). In the case of (K), it is 30.3%, which is approximately 23.3 times that of (F). In the case of (L), it is 24.5%, which is approximately 18.8 times that of (F). In the case of (M), it is 17.6%, which is approximately 13.5 times that of (F). In the case of (N), it is 17.0%, which is approximately 13.1 times that of (F). In the case of (O), it is 16.3%, which is approximately 12.5 times that of (F). In the case of (P), it is 12.5%, which is approximately 9.6 times that of (F). In the case of (Q), it is 17.3%, which is approximately 13.3 times that of (F). In the case of (R), it is 8.2%, which is approximately 6.3 times that of (F).

  From the above experimental results, it is shown that when a pulse voltage is applied, the droplet reaching the position of 100 cm from the nozzle 2 greatly increases as compared with the case where a DC voltage is applied. It is considered that droplets can be adhered farther when a pulse voltage of 2 to 100 Hz having a peak value of 2.25 kV is applied than when .25 kV is applied.

  In addition, the average covered area ratio of the back surface in the cases of (P) and (R) is smaller than that in the case of (F). That is, when the frequency of the pulse voltage is 50 Hz or more, it may be more difficult for droplets to adhere to the back surface than when a DC voltage is applied. Therefore, it is considered that the limit value of the frequency capable of maintaining the average coverage area ratio larger than that when a DC voltage is applied on the back surface is about 100 Hz.

  Next, the relationship between the voltage applied to the electrode 4 and the current flowing through the liquid (droplet) ejected from the ejection port 20 will be described. FIG. 14 is a diagram schematically showing the relationship between the voltage applied to the electrode 4 and the current flowing through the droplets by outputting from the PG 8 a control signal related to a rectangular wave having a duty ratio of 0.1 and a frequency of 4 Hz. is there. In FIG. 14, a sawtooth waveform composed of a thick line represents a voltage waveform applied to the electrode 4, and a waveform composed of a thin line represents a current waveform flowing through a droplet.

  As shown in FIG. 14, at the time when the sawtooth voltage waveform rises substantially vertically, the amplitude of the current waveform is larger than the amplitude at other time points, for example, when the voltage waveform falls in an arc shape. It is thought that the charge amount of the droplet increases from other time points.

  Next, the relationship between the shape of the voltage waveform and the adhesion rate of the chemical solution to the injection target will be described. FIG. 15 is a schematic diagram schematically showing the configuration of the experimental apparatus for confirming the relationship between the shape of the voltage waveform and the adhesion rate of the chemical solution to the injection target, and FIG. 16 shows the output voltage of PG 8 and the nozzle 2 applied thereto. It is a figure which shows the relationship with the measured voltage.

  As shown in FIG. 15, PG 8 is connected to the DC power source 81. Further, the DC power source 81 and the nozzle 2 are connected by the electric wire 5. As shown in FIG. 16, a periodic pulse voltage can be applied from the DC power supply 81 to the nozzle 2 by the output pulse of PG8. The nozzle 2 is connected to the tank 10 via the flow pipe 1. The tank 10 and the nozzle 2 are provided with an insulator 9. Further, apart from the nozzle 2, four dummy trees T1 to T4 are provided along the liquid ejection direction. The experimental apparatus shown in FIG. 15 has a configuration in which the electric wire 5 is directly connected to the nozzle 2 and the liquid is charged by so-called contact charging, and a voltage is applied to the electrode 4 as in the configuration shown in FIGS. Although different from the configuration in which the liquid is charged by so-called induction charging, the charged state of the droplet is considered to depend on the voltage change of the DC power supply 81, so that the purpose of the experiment can be achieved.

  Dummy trees T1 and T3 are arranged on one side and dummy trees T2 and T4 are arranged in order along the injection direction of the nozzle 2 on the other side, with an extension line from the injection port 20 of the nozzle 2 to the injection direction as a boundary. Yes. An interval of 60 cm is provided between the dummy tree T1 and the dummy tree T3 and between the dummy tree T2 and the dummy tree T4. The dummy tree T1 and the dummy tree T2 are opposed to each other, and the dummy tree T3 and the dummy tree T4 are opposed to each other. Each facing distance is 60 cm. The nozzle 2 is located at a substantially middle point of a line segment connecting the dummy tree T1 and the dummy tree T2 in the direction in which the dummy tree T1 and the dummy tree T2 face each other, and is spaced 60 cm from the middle point in the direction opposite to the injection direction. It is placed at the position.

  The dummy trees T1 to T4 are imitated trees, with a brass pipe at the trunk, a stainless steel plate at the leaf, a crocodile clip at both ends of the wire at the branch, and one crocodile clip. The branch is fixed to the brass pipe with the other alligator clip, and the stainless steel plate is sandwiched between them. The height of the dummy trees T1 to T4 is 1.2 m, and the number of leaves is 28 per dummy tree. A filter paper is affixed on both surfaces (front surface and back surface) of 14 leaves out of 28 leaves, and the area of the filter paper on the part where the liquid is adhered is measured.

  The measurement is (a) when a liquid is ejected without applying a voltage to the electrode 4, (i) when a constant DC voltage of 10 kV is applied to the electrode 4 and the liquid is ejected, and (iii) a rectangular value with a peak value of 10 kV. This is performed in the case where a voltage having a shape waveform is applied to the electrode 4 to eject the liquid. In the case of (iii), as shown by the alternate long and short dash line in FIG. 16, a control signal related to a rectangular wave with a duty ratio of 0.5 and a frequency of 0.5 Hz is output from PG8 from PG8 and shown by a solid line. A rectangular pulse voltage is applied to the electrode 4.

  FIG. 17 is a graph showing the adhesion area of the liquid per dummy tree. In the figure, the items of the first, first, second, second, second, third, third, fourth, fourth and fourth back indicate the front and back surfaces of the leaves of the dummy trees 1 to 4, respectively. Of the three bar graphs arranged on the left and right of each item, the left bar graph shows the adhesion area in the case of (A), the middle bar graph shows the adhesion area in the case of (Yes), and the right bar graph is (U) In this case, the adhesion area is shown.

  As shown in FIG. 17, in either case, compared to the case where a rectangular pulse voltage is applied to the electrode 4 (Yes) and the case where a constant DC voltage of 10 kV is applied to the electrode 4 (Yes), The adhesion area is small. In the above-mentioned average coverage area ratio of liquid on the water-sensitive paper, when a sawtooth pulse voltage is applied, the average coverage area ratio is larger than when a constant DC voltage is applied. It is considered that the adhesion amount of is influenced by the voltage waveform. In addition, it is considered that applying the sawtooth pulse voltage improves the adhesion rate of the droplets to the leaves compared to applying the rectangular pulse voltage.

  In addition, as described above, when the voltage waveform has an arc shape, the charge amount of the droplet is reduced, so that a sawtooth pulse voltage is applied rather than applying a pulse voltage having a semicircular waveform to the power supply. It is considered that the rate of adhesion to the leaves of the droplet is improved by applying.

  In the spray device according to the present invention, a sawtooth wave having a large amount of time change is applied to the electrode 4, and a liquid (for example, a medicinal solution) sprayed in a mist form from the spraying port 20 has a dense crop portion and a distant place. Applying enough charge to adhere to the crops, covering the dense part of the crops and the surface of the distant crops with chemicals, improving the spraying efficiency of the chemicals, and controlling the pests reliably it can.

  Further, a constant DC voltage (input voltage) from the DC power supply 81 is converted into a high-frequency pulse voltage, boosted by a step-up transformer 84, and further smoothed by a smoothing circuit 86 to obtain a DC output voltage of a predetermined voltage. At this time, the input voltage is turned on / off at a predetermined frequency using the switch 87, thereby outputting a high-voltage pulse voltage having a predetermined frequency, controlling the frequency of the output voltage, and the charge amount of the injected chemical liquid The charge amount of the injected chemical liquid can be improved.

  In addition, by controlling the voltage frequency to 100 Hz or less, the charge amount of the chemical liquid sprayed from the injection port 20 is maximized, and the dense part of the crop and the surface of the distant crop are reliably covered with the chemical liquid. The spraying efficiency can be improved and the pests can be controlled.

  The pulse voltage generation circuit 80 according to the embodiment is merely an example of a DC-DC converter that generates a sawtooth wave, and instead of the pulse voltage generation circuit 80, another DC-DC converter that generates a sawtooth wave. It goes without saying that may be used. The sawtooth wave is not limited to a waveform that rises steeply and falls gently, but may have a waveform that rises gently and falls sharply according to the specifications of the spraying device.

  Further, the pulse voltage generation circuit 80 according to the embodiment adjusts the voltage applied to the electrode 4 by the output pulse from the PG 8, but controls the timing at which a signal is input to the gate of the FET 83 by the oscillation circuit 82. 4 may be configured to adjust the applied voltage. The FET 83 is a p-type, but an n-type FET may be used instead, and another switching element may be used.

  In addition, the spray device according to the embodiment uses the annular electrode 4, but instead of this, a rod-like electrode is used, and the rod-like electrode is arranged in the vicinity of a plurality of nozzles arranged in parallel on the boom. It may be a configuration.

  Moreover, the spraying apparatus which concerns on embodiment can also spray other liquids, such as a liquid fertilizer, not only a chemical | medical solution.

  The embodiment described above is an exemplification of the present invention, and the present invention can be implemented in variously modified forms within the scope determined based on the description of the claims.

DESCRIPTION OF SYMBOLS 1 Flow pipe 2 Nozzle 3 Accommodating part 4 Electrode 8 Pulse generator 80 Pulse voltage generation circuit 81 DC power supply 82 Oscillation circuit 83 FET
84 Step-up transformer 84a Primary coil 84b Secondary coil 85 Diode 86 Smoothing circuit 87 Switch

Claims (3)

Generates a nozzle having an ejection port for ejecting liquid in the form of a mist, an electrode arranged around the ejection port and imparting electric charge to the liquid ejected from the ejection port, and a pulse voltage to be applied to the electrode In a spraying device comprising a pulse voltage generating means for
The spray apparatus according to claim 1, wherein the pulse voltage generating means generates a sawtooth wave.   The spray device according to claim 1, wherein the pulse voltage generation means is a DC-DC converter.   The spray device according to claim 1 or 2, wherein the frequency of the sawtooth wave is 100 hertz or less.