JP2012182054A - Explosion-proof discharge device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an explosion-proof discharge device which can efficiently radiate an ion generated in a discharge electrode while preventing the intrusion of a foreign matter into a casing.SOLUTION: A casing 1 is connected to an air supply source and also is sealed, and further comprises: a plurality of the discharge electrodes 2 provided at an ion-radiation side; and more number of small holes 3a for air-radiation than the number of the discharge electrodes 2, which are formed at a wall surface 3 provided at the ion-radiation side. In addition, the discharge electrodes 2 are arranged so as to face the small holes 3a for air-radiation.

Description

  The present invention relates to an explosion-proof discharge device that can be used in an environment where explosion-proof specifications are required.

Conventionally, for example, at the electrostatic coating site, after applying a conductive primer, the grounding of the workpiece is confirmed before the main coating is performed.
In this way, the grounding of the workpiece is confirmed by connecting the ground wire to the workpiece during the main coating by electrostatic painting. If the ground wire is disconnected or has a poor contact, If it is not removed, the workpiece will be charged at a high potential during the painting process, and it is dangerous if a discharge occurs between the ground zone and a spark occurs.
Further, even if electrostatic coating is performed with insufficient grounding, a proper coating film may not be formed, resulting in poor coating.

Therefore, it is confirmed whether or not the work to be grounded is grounded. As the method, the following method is known.
In the method described in Patent Document 1, a ground wire is connected to a workpiece coated with a conductive paint, and the surface is charged by radiating ions to the workpiece, and then a non-contact surface potentiometer is used. This is to measure the potential of the workpiece surface.
If there is no defect in the conductive coating film on the workpiece and the ground wire is connected and properly grounded, the surface potential measured by the electrometer should be low. Therefore, it can be seen from the measured surface potential whether the workpiece is grounded.
By using such a method, the approximate electrical resistance value of the workpiece can be obtained (see Patent Document 2).

In order to charge the workpiece for the purpose of confirming the ground as described above, a discharge device that emits ions is used. However, a spark due to discharge may occur from the tip of the discharge electrode to which a high voltage is applied. For example, when a foreign substance such as metal powder approaches the discharge electrode, a spark is generated in the meantime, which is dangerous.
In particular, if a spark is generated at a site using an organic solvent such as the above-mentioned coating site, it may ignite the organic solvent.
Therefore, the discharge device used in the above-described flammable environment must be an explosion-proof discharge device. As an explosion-proof discharge device, there is known a discharge device in which a discharge electrode is covered with a casing and a small hole having a size to prevent entry of foreign matter from the outside is formed on a surface on which ion wind is radiated. And the ion produced | generated by the said discharge electrode is radiated | emitted from the said small hole as an ion wind with the air supplied to a casing.

Japanese Patent No. 3611037 Japanese Patent No. 4388059

As described above, in the explosion-proof discharge device that covers the tip side of the discharge electrode, the ion wind generated by the discharge electrode is narrowed by the small hole having the small opening so that the amount of ions emitted to the outside of the casing is small. There was a problem of becoming. Thus, if the amount of ions radiated to the workpiece is reduced, the workpiece cannot be charged. In order to increase the amount of ions generated at the discharge electrode, it is conceivable to increase the applied voltage, but there is a limit to increasing the applied voltage, and if the generated ions are not emitted, the efficiency is poor. .
An object of the present invention is to provide an explosion-proof discharge device that can efficiently radiate ions generated by a discharge electrode while preventing foreign matter from entering the casing.

  The first invention is a casing which is connected to an air supply source and is hermetically sealed, wherein a plurality of discharge electrodes are provided on the ion emission side, and a wall surface provided on the ion emission side is provided with the number of discharge electrodes. In addition, a large number of small holes for air emission are formed, and the discharge electrode is opposed to the small holes for air emission.

  According to a second aspect of the present invention, there is provided an electrode position adjusting means that can change a distance from the tip of the discharge electrode to the wall.

  The third invention is characterized in that a power supply control circuit for controlling a high voltage applied to the radiation electrode is housed in the casing.

  The fourth invention is characterized by comprising a pressure sensor for detecting the pressure in the casing.

  In a fifth aspect of the present invention, on the ion emission side in the casing, an air introduction path made of an insulating material that is continuous with the air emission small hole and has a flow path cross section larger than the opening of the air emission small hole is provided. The tip of the discharge electrode is provided in the air introduction path.

According to the present invention, it is possible to efficiently emit ions generated by the discharge electrode while preventing foreign matters from entering the casing.
In particular, since the small holes for air emission are provided in addition to the positions corresponding to the discharge electrodes where ions are generated, the air flowing in the casing is made while keeping the size of the individual small holes so that no foreign matter is mixed in. Can be ensured. Therefore, the generated ions can be efficiently radiated on the air.

In the second invention, since the electrode position can be adjusted, the amount of ion radiation can be adjusted according to the electrode position, and charging and static elimination according to the purpose can be performed.
In the third invention, since the high voltage control circuit is accommodated in the casing, a high voltage cable is not required outside the casing. When connecting from the casing to the external power supply with a high-voltage cable, the length of the high-voltage cable becomes long, and in the meantime, the high voltage is drawn around, which is dangerous. The current leaking from the cable may affect other electronic devices as electrical noise. However, according to the third aspect of the invention, a normal low voltage cable, for example, one having a direct current of 10 V or less can be used outside the casing, so that the above problem does not occur.

  In the fourth aspect of the invention, since the pressure in the casing can be detected by providing a pressure sensor, the air supply source connected to the casing is controlled so that the pressure in the casing becomes higher than the external pressure, and the air purge is performed reliably. be able to. And if it controls to apply a high voltage to a discharge electrode after performing an air purge, while being able to discharge | emit the foreign material in a casing, it can prevent more reliably that a foreign material mixes from the small hole for air discharge | release. .

  According to the fifth aspect of the invention, the air supplied to the casing is guided to the air emission small hole via the air introduction path, and the air in the casing flows toward the air emission small hole without waste. And the ion produced | generated by the front-end | tip of the discharge electrode provided in the said air introduction path rides on the said air flow, and is radiated | emitted more efficiently.

FIG. 1 is an external view of a discharge device according to an embodiment. FIG. 2 is a bottom view of the embodiment with the rear end side cover removed. FIG. 3 is a plan view showing the ion emission side of the embodiment. 4 is a cross-sectional view taken along line IV-IV in FIG. 5 is a cross-sectional view taken along line VV in FIG.

The discharge device shown in FIGS. 1 to 5 is an explosion-proof device provided with three discharge electrode needles 2 (see FIGS. 2 and 4) which are discharge electrodes of the present invention in a cylindrical casing body 1. .
The casing body 1 is a cylindrical member made of a conductive material such as aluminum and having both ends opened. A metal front disk 3 and a pressing plate 4 are provided at the front end, and a rear end is covered with a cover member 5. Covering.
A mounting block 6 for fitting the front disc 3 and the holding plate 4 is press-fitted to the inner periphery of the casing body 1 and a sealing block 7 is press-fitted to the inner periphery of the rear end. Yes.
And it is the said casing main body 1, Comprising: Between the said sealing block 7 and the said whole surface disk 3 is the inside of the sealed casing of this invention.

Further, as shown in FIGS. 4 and 5, a resin cylindrical member 8 having a shorter axial length than the casing body 1 is press-fitted into the inner periphery of the casing body 1, and the mounting block 6 and the sealing block 7 are pressed. A part thereof is press-fitted into the cylindrical member 8 and fixed to the casing body 1.
4 is a sectional view taken along line IV-IV in FIG. 2, and FIG. 5 is a sectional view taken along line VV in FIG.

The mounting block 6 shown in FIG. 4 is a disk-shaped block made of an insulating resin, and is press-fitted into the casing body 1 and is stopped by a screw member 14 from the side surface.
The mounting block 6 is formed with a plurality of air introduction passages 6a penetrating in the axial direction, and is provided with a circular recess 6b into which the front disc 3 is fitted on the front surface.

As shown in FIGS. 2 and 4, the front disk 3 is a metal member in which a plurality of small holes for air emission 3 a are formed, and the air introduction path 6 a for the small holes for air emission 3 a and the mounting block 6. The center of the front disc 3 is fixed to the mounting block 6 with a hexagon socket head bolt 25.
Furthermore, the front disk 3 and the surface of the mounting block 6 are covered with a ring-shaped metal pressing plate 4, and the pressing plate 4 is fixed to the mounting block 6 with a plurality of bolts 25.

In this embodiment, six air emission small holes 3a and six air introduction paths 6a are formed. However, the number is not limited to six, and it is only necessary that the small holes 3a for air emission correspond to the air introduction path 6a.
The air emission small holes 3a have an opening diameter that can prevent foreign substances from entering. In this embodiment, all the air emission small holes 3a have an opening diameter of less than 1 mm. Have the same dimensions. Then, the six air radiating small holes 3a are arranged at equal intervals on the circumference having the center of the front disc 3 as the center of the circle (see FIG. 2).

  Three electrode needles 2 are attached to the rear of the attachment block 6. The number of electrode needles 2 is not limited to three, and the number may be determined according to the required ion amount, applied voltage, and the like. However, the number of the air radiating small holes 3 a is set to be larger than the number of the electrode needles 2.

As shown in FIGS. 2 and 4, the three electrode needles 2 are attached to the tip of a plate-like protruding portion 9 a protruding in three directions of the electrode holding member 9. The electrode holding member 9 is a conductive member such as stainless steel, and includes a screw hole 9b in which a female screw is formed in the protruding portion 9a.
Further, a threaded portion 2 a made of an external thread is formed on the outer periphery of the electrode needle 2, and the threaded portion 2 a is screwed into the threaded hole 9 b so that the electrode needle 2 is fixed to the holding member 9.
Further, a set nut 10 is screwed into the threaded portion 2a of the electrode needle 2 to fix its position.

In other words, if the locking nut 10 is loosened, the electrode needle 2 can be rotated and moved in the axial direction.
Therefore, in this embodiment, the screw position 2a formed on the outer periphery of the electrode needle 2 and the screw hole 9b of the electrode holding member 9 constitute the electrode position adjusting means of the present invention.
If the position of the electrode needle 2 is changed, the distance from the tip of the electrode needle 2 to the small hole 3a for air emission changes, so that the amount of ion radiation can be changed.
However, the amount of ion radiation is affected not only by the position of the electrode needle 2, but also by the number of electrode needles 2, the voltage applied to the electrode needle 2, the air flow rate, and the like. Need to adjust.

The resin support member 11 is inserted and fixed at the center of the electrode holding member 9 holding the electrode needle 2 as described above, and the support member 11 is attached to the center of the mounting block 6. At this time, the tip of each electrode needle 2 is made to face the air emission small hole 3a.
A screw portion 11a is provided on the outer periphery of the tip of the support member 11, and a screw hole 6c that is screw-coupled to the screw portion 11a is formed at the center of the mounting block 6, and is supported by the screw portion 11a and the screw hole 6c. The member 11 is fixed to the mounting block 6.
The electrode needle 2 and the front disc 3 are electrically insulated by interposing the resin support member 11 and the mounting block 6.

A power supply control circuit 12 to be described later is connected to the electrode holding member 9 so that a high voltage is applied to the electrode needle 2 through the electrode holding member 9.
As shown in FIG. 4, the power control circuit 12 is attached to the attachment block 6 via a support member 13. The power supply control circuit 12 is a circuit that is composed of a printed circuit board on which a step-up transformer (not shown) is mounted, converts the voltage supplied from the external power supply into a high voltage, and outputs the voltage to the electrode needle 2.
As described above, in this embodiment, since the power supply control circuit 12 that outputs a high voltage is provided in the casing body 1, it is not necessary to provide a high voltage cable outside the casing body 1. For this reason, it is possible to eliminate the danger caused by leakage or discharge due to the high-voltage cable being routed, and the adverse effects of noise on other electronic devices.

On the other hand, the sealing block 7 press-fitted to the rear end side of the casing main body 1 is composed of a ring-shaped first member 7a and a second member 7b fixed to this with a screw member 14, as shown in FIG. A part of the first member 7 a is inserted into the cylindrical member 8 and the whole is press-fitted into the casing body 1.
FIG. 3 is a bottom view of the casing body 1 with the cover 5 on the rear end side removed, showing the outer surface of the sealing block 7.

As shown in FIG. 3, a mounting hole 17 and an air supply hole 19 are passed through the resin sealing block 7.
The mounting hole 17 is a hole for mounting a connector 16 (see FIG. 1) for connecting the low voltage cable 15 connected to an external controller (not shown) and the power control circuit 12 in the casing. The air supply hole 19 is a hole for attaching an air tube 18 (see FIG. 1) connected to an air supply source (not shown).
The cover member 5 is formed with a hole for drawing out the connector 16 and the air tube 18.

As shown in FIGS. 3 and 5, the sealing block 7 is formed with a pair of mounting recesses 20 and 20, and each of the mounting recesses 20 and 20 has a pressure for detecting the pressure in the casing. Sensors 21 and 21 are attached. In these pressure sensors 21, a pair of locking nuts 22 and 23 are attached to a screw portion 21b on the outer periphery of the detection portion 21a that penetrates the bottom surface of the mounting recess 20, and the bottom surface of the mounting recess 20 is sandwiched between the locking nuts 22 and 23. Thus, the sealing block 7 is fixed.
And the signal line of this pressure sensor 21 is connected to the display part which is not shown in figure through the said connector 16, and the detected value is displayed.
As described above, the pair of pressure sensors 21 is provided on the casing body 1 so that the detection signal of the other pressure sensor 21 can be confirmed when one of the pressure sensors 21 fails.
In FIG. 4, reference numeral 24 denotes an O-ring.

The operation of the explosion-proof discharge device of this embodiment configured as described above will be described below.
In addition, when using this discharge device, a ground wire is connected to the casing body 1.
First, air is supplied from the air supply source into the casing body 1 through the air tube 18, and the display unit confirms that the detection value of the pressure sensor 21 becomes a predetermined pressure, and then the power is turned on. To.
The predetermined pressure is a pressure at which the air supplied into the casing is reliably released from the air emission small hole 3a of the front disc 3. That is, the pressure is higher than the external pressure.

Thus, by checking the pressure of the pressure sensor 21, a high voltage can be applied after air purging inside the casing body 1, that is, around the electrode needle 2.
By this air purge, foreign matter in the casing body 1 can be discharged before a high voltage is applied to the electrode needle 2, and the air radiation is introduced into the casing body 1 from the small holes 3 a for air emission when a high voltage is applied. Foreign matter smaller than the small hole 3a can be prevented from entering.
Accordingly, it is possible to prevent a foreign matter such as metal powder from approaching the electrode needle 2 in a state where a high voltage is applied and a spark due to discharge.

As described above, when air is supplied into the casing body 1 from the air supply source, the air is radiated from the six air radiating small holes 3a. At this time, since air is guided to the air emission small hole 3a by the air introduction path 6a formed in the mounting block 6, the air in the casing 1 flows in the axial direction without much disturbance.
When a high voltage is applied to the electrode needle 2 in a state where such an axial air flow is formed, ions generated on the distal end side of the electrode needle 2 ride on the air flow and become an ion wind, and the electrode needle 2 Is radiated from the air radiating small hole 3a opposed to the.
In this embodiment, since the air radiating small hole 3a is provided at a position facing the electrode needle 2, the generated ions are immediately radiated on the air flow, and the ion wind is radiated to the outside. It is difficult to neutralize by colliding with the side surface of the main body 1 or the like. That is, the generated ions can be emitted efficiently.

In addition, the said ion wind is mainly radiated | emitted from the air emission small hole 3a corresponding to the electrode needle 2, and air with low ion concentration is radiated | emitted from the other air emission small hole 3a. Thus, the air emission small hole 3a that does not face the tip of the electrode needle 2 hardly emits ions. The reason for providing such an air emission small hole 3a is as follows.
In this explosion-proof discharge device, the diameter of the air radiation small hole 3a is set to less than 1 mm so that foreign matter is not easily mixed in the casing body 1, but the diameter of the air radiation small hole 3a is thus reduced. If the value is made small, air may not flow smoothly. If the air does not flow smoothly, the generated ions are neutralized in the casing body 1, and the ion wind is not emitted to the outside. Therefore, in this embodiment, in order to secure the air supply flow rate and create a smooth flow, the number of the air radiation small holes 3a is increased by the amount of the diameter of the air radiation small holes 3a being reduced. It is.

If the number of small holes 3a for air emission is increased in this way, even if the opening diameter of each small hole 3a for air emission is reduced, the cross-sectional area of the air flow path by all openings can be increased. Wind is radiated smoothly.
Therefore, the explosion-proof discharge device of this embodiment can radiate an ion wind efficiently even when the opening diameter of each small hole 3a for air emission is small, and can thereby be sufficiently charged.
The reason why the number of air emission small holes 3a is larger than the number of electrode needles 2 is to set the total number of air emission small holes 3a according to the number of electrode needles 2. This is because as the number of electrode needles 2 increases, so many ions are generated, so that a larger air flow rate is required to radiate the ions to the outside.

As described above, the explosion-proof discharge device according to this embodiment is configured so that the electrode needle 2 is not contaminated around the electrode needle 2 provided in a sealed casing while causing the generation of a spark. The ions generated in 2 can be emitted efficiently without waste.
The explosion-proof discharge device is configured to apply a high voltage to the electrode needle 2 after supplying air and confirming that the pressure in the casing is equal to or higher than the treatment pressure. Confirmation and power control may be performed manually by an operator or automatically by a controller.
When a controller is used, the signal line of the pressure sensor 21 is connected to the controller, and on / off of the output of the power supply control circuit 12 is controlled according to the detection signal.

Also, when the explosion-proof discharge device is used as an earth checker, an air supply source and a surface potential meter are connected to the controller to start air supply, turn on the power, start measurement of the surface potential meter, etc. The timing can also be automatically controlled.
Further, in the explosion-proof discharge device of the above embodiment, the power supply control circuit 12 can change the polarity of the output voltage alternately between plus and minus, so that not only as a charging device but also plus / minus It can also be used as a static elimination device for explosion-proofing that alternately emits ions.

  The explosion-proof discharge device of the present invention is useful as a charging device or a charge removal device in various environments where explosion-proof specifications are required.

DESCRIPTION OF SYMBOLS 1 Casing body 2 Electrode needle 3 Front disk 3a Air emission small hole 6a Air introduction path 7 Sealing block 12 Power supply control circuit 18 Air tube 21 Pressure sensor

Claims (5)

  A casing that is connected to an air supply source and is hermetically sealed, provided with a plurality of discharge electrodes on the ion emission side, and on a wall surface provided on the ion emission side with a larger number of air emission smaller than the number of discharge electrodes. An explosion-proof discharge device in which a hole is formed and the discharge electrode is opposed to a small hole for air emission.   2. The explosion-proof discharge device according to claim 1, further comprising electrode position adjusting means for changing a distance from a tip of the discharge electrode to the wall.   The explosion-proof discharge device according to claim 1 or 2, wherein a power supply control circuit for controlling a high voltage applied to the radiation electrode is accommodated in the casing.   The explosion-proof discharge device according to any one of claims 1 to 3, further comprising a pressure sensor that detects a pressure in the casing.   An air introduction path made of an insulating material having a flow passage cross section larger than the opening of the air emission small hole is provided on the ion emission side in the casing and is continuous with the air emission small hole. The explosion-proof discharge device according to any one of claims 1 to 4, wherein a tip of the discharge electrode is provided.

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