Discharge devices and electrostatic precipitators

Abstract

To provide a discharge device and an electric dust collector which can enhance charge efficiency with simple configurations.SOLUTION: A discharge device includes a discharge electrode (310), a counter electrode (320) arranged so as to face the discharge electrode (310), and a voltage application part for applying a voltage to the discharge electrode (310). The counter electrode (320) has a conductive part (321) formed of a plate-like conductor, and a coating part (322) which is formed of an insulator and coats the surface of the conductive part (321). The coating part (322) has a first coating part (323) and a second coating part (324). The conductive part (321) has a first main surface (321a) coated with the first coating part (323), a second main surface (321b) coated with the second coating part (324), and side faces (321c). Exposed exposure surfaces (321c1) are formed in at least a part of the side faces (321c).SELECTED DRAWING: Figure 10

Description

Technical Field

[0001] The present invention relates to a discharge device and an electrostatic precipitator.

Background Art

[0002] Conventionally, as an example of an electrostatic precipitator, it is known to include a discharge device having a discharge electrode and a counter electrode disposed in a pair with the discharge electrode, wherein the surface of the counter electrode in such a discharge device is coated with an insulator (see, for example, Patent Document 1).

Prior Art Literature

Patent Literature

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problem to be Solved by the Invention

[0004] The inventors of the present application have found that when a counter electrode coated with an insulator is used, if the voltage applied to the discharge electrode is set within a predetermined range, pulsed discharge intermittently occurs from the counter electrode side (see Patent Document 2).

[0005] In this conventional technique, since the entire surface of the counter electrode is covered with a resin insulating coating, the counter electrode can be formed easily, but there is room for further improvement in terms of increasing charging efficiency.

[0006] The disclosed technology has been made in view of the foregoing, and an object thereof is to provide a discharge device and an electrostatic precipitator that can increase charging efficiency with a simple configuration.

Means for Solving the Problem

[0007] One embodiment of a discharge device disclosed in this application comprises a discharge electrode, a counter electrode disposed opposite to the discharge electrode, and a voltage application unit for applying a voltage to the discharge electrode. The counter electrode has a conductive portion formed of a plate-shaped conductor and a covering portion formed of an insulator that covers the surface of the conductive portion. The covering portion has a first covering portion and a second covering portion. The conductive portion has a first main surface covered by the first covering portion, a second main surface covered by the second covering portion, and a side surface. An exposed surface is formed on at least a portion of the side surface. [Effects of the Invention]

[0008] According to this disclosure, charging efficiency can be increased with a simple configuration. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a schematic diagram of an air purifier equipped with a discharge device according to an embodiment, and an electrostatic precipitator that includes the discharge device. [Figure 2] Figure 2 is a diagram showing the configuration of an electrostatic precipitator according to an embodiment. [Figure 3] Figure 3 is a schematic diagram showing the discharge electrode and counter electrode of the charging section according to the embodiment. [Figure 4] Figure 4 shows the waveform of the discharge current in the charging section according to the embodiment. [Figure 5] Figure 5 is an explanatory diagram illustrating the process by which a pulse current with opposite polarity to the applied voltage is generated due to dielectric breakdown of the counter electrode in the charging section according to the embodiment. [Figure 6] Figure 6 is a schematic diagram of the charged section of the embodiment as viewed from the ventilation direction. [Figure 7] Figure 7 is a schematic diagram of the charged section of the embodiment, viewed from the side perpendicular to the ventilation direction. [Figure 8] Figure 8 is a top view showing the discharge electrode and counter electrode of the charging section according to the embodiment. [Figure 9] Figure 9 is a side view of the discharge electrode and counter electrode of the charging section of the embodiment, as seen from the ventilation direction. [Figure 10] Fig. 10 is a cross-sectional view taken along line A-A in Fig. 8. [Figure 11] Fig. 11 is a cross-sectional view showing the discharge electrode and the counter electrode of the charging unit according to Modified Example 1 of the embodiment. [Figure 12] Fig. 12 is a cross-sectional view showing the discharge electrode and the counter electrode of the charging unit according to Modified Example 2 of the embodiment. MODE FOR CARRYING OUT THE INVENTION

[0010] Hereinafter, embodiments of the discharge device and the electrostatic precipitator disclosed in the present application will be described in detail with reference to the drawings. The discharge device and the electrostatic precipitator disclosed in the present application are not limited by the following embodiments.

[0011] In addition, the constituent elements described in the following description include those that can be easily substituted by a person skilled in the art, those that are substantially identical, i.e., those that fall within the scope of equivalents. Throughout the description of the embodiments, the same elements are denoted by the same reference numerals.

[0012] In addition, in the following embodiments, the case where the discharge device according to the disclosed technology is applied to an electrostatic precipitator provided in an air cleaner is described. However, the present invention is not limited thereto, and the discharge device according to the disclosed technology can also be applied to, for example, various devices capable of generating ions by charging.

[0013] <Configuration of Air Cleaner> First, the configuration of the air cleaner 1 according to the embodiment will be described with reference to Fig. 1. Fig. 1 is a schematic configuration diagram of the air cleaner 1 provided with the discharge device according to the embodiment and the electrostatic precipitator 2 including the discharge device.

[0014] As shown in Fig. 1, the air cleaner 1 includes a housing 10 that accommodates devices for purifying air. The housing 10 is formed, for example, of a synthetic resin material into a rectangular parallelepiped shape. The housing 10 is formed with a suction port 11 for sucking indoor air and an air outlet 12 for blowing purified air into the room.

[0015] Further, a pre-filter 14, a plurality of electrostatic precipitators 2, and a deodorizing filter 5 are provided inside a housing 10. The electrostatic precipitator 2 is an example of a dust collector. The pre-filter 14 removes large dust from sucked air. The plurality of electrostatic precipitators 2 collect dust in air that has passed through the pre-filter 14 by electrostatic force. The deodorizing filter 5 performs deodorization treatment on air that has passed through the electrostatic precipitators 2.

[0016] For example, the pre-filter 14 has a mesh structure woven from filamentous PET (polyethylene terephthalate) material, and is held by a resin frame (not shown). The pre-filter 14 collects relatively large dust contained in air sucked into the housing 10.

[0017] Each of the plurality of electrostatic precipitators 2 includes a charging section 3 and a dust collecting section 4. The charging section 3 is an example of a discharge device, and charges fine particles such as dust contained in passing air. The dust collecting section 4 collects the fine particles charged by the charging section 3 by electrostatic force.

[0018] Note that in the present embodiment, three electrostatic precipitators 2 are arranged inside the housing 10, but the number of arranged electrostatic precipitators is not limited in any way.

[0019] The deodorizing filter 5 uses a catalyst filter to perform deodorization treatment that removes odorous components such as ammonia and methyl mercaptan, and harmful components such as formaldehyde from air from which dust has been removed by the pre-filter 14 and the electrostatic precipitators 2.

[0020] Further, a fan 6, a fan motor 61, a control board 7, a dust sensor 13, and an operation display board 15 are provided inside the housing 10. The fan 6 is arranged on the downstream side of the deodorizing filter 5. The fan motor 61 rotates the fan 6.

[0021] The control board 7 controls the air purifier 1. The dust sensor 13 detects the dust concentration in the air drawn in from the intake port 11. The operation display board 15 performs operations such as starting and stopping the operation.

[0022] Furthermore, the housing 10 is equipped with a single constant-voltage high-voltage power supply unit for each dust collection unit 4 of each electrostatic precipitator 2 (hereinafter referred to as the "high-voltage power supply 40 for dust collection units").

[0023] On the other hand, a constant-current high-voltage power supply unit for the charging unit (hereinafter referred to as "high-voltage power supply 30 for the charging unit") that supplies power to the charging unit 3 is provided for each of the three charging units 3. Such a high-voltage power supply 30 for the charging unit is an example of a voltage application unit.

[0024] In the air purifier 1 having this configuration, the fan 6 driven by the fan motor 61 rotates to draw in indoor air from the intake port 11 as indicated by the arrow f (hereinafter also referred to as the airflow direction f), purifies the air as it passes through the pre-filter 14, the electrostatic precipitator 2, and the deodorizing filter 5, and blows the purified air into the room from the outlet port 12.

[0025] In addition, while the airflow setting of the air purifier 1 can be manually switched based on the operation of the control display board 15, an automatic airflow mode setting can also be provided that automatically switches to an appropriate airflow based on the detection signal of the dust sensor 13, for example.

[0026] <Configuration of an electrostatic precipitator> Next, the configuration of the electrostatic precipitator 2 equipped with a discharge device according to the embodiment will be described with reference to Figure 2. Figure 2 is a configuration diagram of the electrostatic precipitator 2 according to the embodiment.

[0027] As shown in Figure 2, the electrostatic precipitator 2 comprises a charging unit 3 and a dust collection unit 4. The charging unit 3 has a discharge electrode 310 and a counter electrode 320.

[0028] The discharge electrode 310 is a wire-shaped electrode. The counter electrode 320 is a flat plate-shaped electrode having a different polarity from the discharge electrode 310. In the charging section 3, multiple discharge electrodes 310 and multiple counter electrodes 320 are arranged alternately at predetermined intervals.

[0029] The dust collection unit 4 has a structure in which a large number of flat plates are arranged in parallel and electrically connected so that a high voltage is applied between adjacent electrodes. In this embodiment, of the two types of electrodes that make up the dust collection unit 4, the electrode with the same polarity as the discharge electrode 310 is called the "high-voltage electrode 410", and the electrode with the same polarity as the counter electrode 320 is called the "collection electrode 420".

[0030] A high voltage is applied to the discharge electrode 310 of the charging section 3 by the high-voltage power supply 30 for the charging section. The high-voltage power supply 30 for the charging section is powered by the power supply 50 via the power supply unit 55 and is driven and controlled by the control unit 70 mounted on the control board 7 (see Figure 1) via the charging section switches 301, 302, and 303. The counter electrode 320 of the charging section 3 is grounded.

[0031] A high voltage is applied to the high-voltage electrode 410 of the dust collection unit 4 by the high-voltage power supply 40 for the dust collection unit. The high-voltage power supply 40 for the dust collection unit is powered from the power supply 50 via the power supply unit 55 and is driven and controlled by the control unit 70 mounted on the control board 7 via the dust collection unit switch 401. The collection electrode 420 of the dust collection unit 4 is grounded.

[0032] The number of high-voltage power supplies 30 for the charging section is the same as the number of charging sections 3 built into the electrostatic precipitator 2 (3 in this case), and is connected in a one-to-one correspondence with the charging section 3 of each electrostatic precipitator 2. There is one high-voltage power supply 40 for the dust collection section, regardless of the number of dust collection sections 4 built into the electrostatic precipitator 2, and all dust collection sections 4 are connected in parallel. The number of high-voltage power supplies 30 for the charging section and the number of high-voltage power supplies 40 for the dust collection section are not particularly limited.

[0033] <Configuration of the charging section> Next, the configuration of the charging section 3 according to the embodiment will be described with reference to Figures 3 to 10. Figure 3 is a schematic diagram showing the discharge electrode 310 and the counter electrode 320 of the charging section 3 according to the embodiment.

[0034] The discharge electrode 310 is formed in a wire shape, and Figure 3 shows a cross-section of the wire-shaped discharge electrode 310. The discharge electrode 310 only needs to have a thin or sharp shape in at least a portion of it; it can be needle-shaped instead of wire-shaped.

[0035] On the other hand, the counter electrode 320 is formed in a flat plate shape and has a conductive portion 321 and a covering portion 322. The conductive portion 321 is formed of a plate-shaped conductor, such as stainless steel SUS304 or aluminum.

[0036] In this embodiment, the outer surface of the conductive portion 321 includes a first main surface 321a, a second main surface 321b opposite to the first main surface 321a, and a side surface 321c connecting the first main surface 321a and the second main surface 321b.

[0037] The covering portion 322 is made of an insulator and covers the first main surface 321a and the second main surface 321b of the conductive portion 321. The covering portion 322 also has a plate-shaped first covering portion 323 that covers the first main surface 321a and a plate-shaped second covering portion 324 that covers the second main surface 321b.

[0038] The first coating portion 323 and the second coating portion 324 are formed of, for example, an insulator containing organic matter. The first coating portion 323 and the second coating portion 324 are formed of, for example, an insulating material containing organic matter (for example, a resin such as polyvinyl chloride resin or fluororesin).

[0039] The volume resistivity of the first coating portion 323 and the second coating portion 324 is 10 7 It is good if it is (Ω·cm) or more, 10 9 It is desirable that the density be (Ω·cm) or greater. The thickness of the first covering portion 323 and the second covering portion 324 is, for example, about 0.5 (mm).

[0040] Furthermore, the first coating portion 323 and the second coating portion 324 are not limited to being formed of an insulator containing organic material, but may also be formed of an insulator containing inorganic material (for example, ceramic such as alumina).

[0041] On the other hand, the covering portion 322 does not cover at least a portion of the side surface 321c of the conductive portion 321. That is, the counter electrode 320 has an exposed portion 326 on at least a portion of the side surface 321c of the conductive portion 321 in which such side surface 321c is exposed.

[0042] The counter electrode 320 having such a configuration can suppress the discharge current between it and the discharge electrode 310, and consequently, it can also suppress the generation of ozone.

[0043] Figure 4 shows the waveform of the discharge current in the charging section 3 according to the embodiment. As shown in Figure 4, it can be seen that intermittent pulses with large discharge current values ​​appear mixed in with a large number of continuous pulses with small discharge current values.

[0044] The continuous pulses with small discharge current values ​​indicate a discharge originating near the discharge electrode 310, caused by a charge of the same polarity (positive polarity in this embodiment) as the voltage applied to the discharge electrode 310, and are so-called burst pulse corona discharges.

[0045] On the other hand, pulses with large discharge current values ​​indicate discharge caused by charges originating near the counter electrode 320, which have opposite polarity (negative polarity in this embodiment) to the voltage applied to the discharge electrode 310.

[0046] From these experimental results, it was found that when the conductive portion 321 of the counter electrode 320 is covered with the covering portion 322 and a limited range of DC voltage is applied to the discharge electrode 310, a pulsed discharge current with opposite polarity to the voltage applied to the discharge electrode 310 is intermittently generated from the vicinity of the counter electrode 320.

[0047] Here, we will explain the mechanism by which pulsed, intermittent discharge current is generated from the counter electrode 320. Figure 5 is an explanatory diagram showing the process by which a pulsed current with opposite polarity to the applied voltage is generated due to dielectric breakdown at the counter electrode 320 in the charged section 3 according to the embodiment.

[0048] As shown in Figure 5(a), for example, when a predetermined positive DC voltage is applied to the discharge electrode 310, positive ions (positively polar ions) are generated near the discharge electrode 310 by corona discharge and are attracted towards the counter electrode 320.

[0049] As a result, as shown in Figure 5(b), positive ions accumulate on the surface of the coating portion 322 of the counter electrode 320. At this time, electrons become unevenly distributed near the coating portion 322 on the conductive portion 321 of the counter electrode 320, and a potential difference (voltage) is generated between the surface of the coating portion 322 and the vicinity of the coating portion 322 on the conductive portion 321.

[0050] As more charge accumulates, the potential difference increases, and when it reaches a certain potential difference, dielectric breakdown occurs in the air layer, causing electrons to be ejected at high speed from inside the conductive part 321 of the counter electrode 320, as shown in Figure 5(c).

[0051] In this case, if a groove-shaped exposed portion 326 exists within the counter electrode 320, a discharge will occur that penetrates the interior of the groove 327 (see Figure 10) through the interface between the air layer in the groove 327 and the covering portion 322 facing the groove 327.

[0052] In other words, the accumulation of charge on the surface of the coating portion 322 causes a phenomenon in which pulsed discharge current is intermittently generated from the counter electrode 320. In this case, the discharge state is thought to be intermittent pulsed discharge when the electrical resistance formed by the charge-accumulating coating portion 322 and the groove 327 is appropriate.

[0053] From the above, the presence of the exposed portion 326 on the counter electrode 320 makes dielectric breakdown of the air layer in the counter electrode 320 more likely, and enables the stable generation of a pulsed discharge current. Furthermore, the formation of the exposed portion 326 on the bottom surface of the groove 327 prevents discharge from occurring before sufficient charge has accumulated in the coating portion 322, and enables the stable generation of a pulsed discharge due to the charge accumulated in the coating portion 322.

[0054] Electrons that are ejected at high speed from near the counter electrode 320 due to dielectric breakdown have a large amount of energy and collide one after another with nitrogen molecules (N2) which are abundant in the air. And with each collision with a nitrogen molecule (N2), the high-speed electrons knock electrons away from the nitrogen molecule (N2).

[0055] A nitrogen molecule (N2) that has lost electrons becomes a positive ion (N2) + ) and is attracted towards the counter electrode 320. Note that positive ions (N2 + Because it is unstable, it steals electrons from nearby water molecules and returns to a stable nitrogen molecule (N2).

[0056] On the other hand, electrons ejected from nitrogen molecules (N2) combine with nearby oxygen molecules (O2), as shown in Figure 5(d). The resulting negative ions (O2) are formed by the electrons combining with the oxygen molecules. - These negative ions are attracted to the discharge electrode 310 along the electric field. These negative ions cause fine particles such as dust to become negatively charged.

[0057] In this embodiment, a voltage of a first polarity (for example, "positive") is applied to the discharge electrode 310 to generate corona discharge near the discharge electrode 310. As a result, ions of the first polarity are generated near the discharge electrode 310, and dielectric breakdown occurs at the coating portion 322 of the counter electrode 320, causing intermittent pulsed discharges with large discharge currents to occur from the counter electrode 320.

[0058] As a result, a large amount of ions with a second polarity (for example, "negative") are generated on the side of the counter electrode 320.

[0059] Based on the experiments described above, it is possible to provide an electrostatic precipitator 2 that can improve the amount of charge applied to dust and the charging efficiency (the amount of charge obtained relative to the power consumed by the discharge device) compared to conventional devices by using ions generated near the counter electrode 320 of the charging unit 3. Moreover, it is expected that ozone generation will also be suppressed.

[0060] Figures 6 and 7 are schematic diagrams showing an example of the configuration of the charging section 3 of the embodiment. Figure 6 is a schematic diagram of the charging section 3 of the embodiment viewed from the ventilation direction f (see Figure 7). Figure 7 is a schematic diagram of the charging section 3 of the embodiment viewed from the side perpendicular to the ventilation direction f.

[0061] In the embodiment, the discharge electrode 310 can use, for example, multiple (four in the figures) tungsten wires with a diameter Φ of 0.12 (mm) and an effective length of 100 (mm), as shown in Figures 6 and 7.

[0062] These multiple wires are arranged so as to be parallel to each other, and so as to be perpendicular to the ventilation direction f (left-right direction in Figure 7) in their longitudinal direction (the direction perpendicular to the plane of the paper in Figure 7).

[0063] Furthermore, for the conductive portion 321 of the counter electrode 320, for example, a rectangular parallelepiped plate made of stainless steel can be used, having a width w along the ventilation direction f of 10 mm, a longitudinal length l parallel to the wire-shaped discharge electrode 310 of 100 mm, and a plate thickness t of 0.5 mm. Also, for the covering portion 322, for example, a plate made of ABS resin with a thickness of 0.5 mm can be used.

[0064] The counter electrode 320 can have a structure in which a single plate-shaped body, which is the conductive portion 321, is sandwiched from both sides in the thickness direction by two plate-shaped bodies, which are the covering portions 322. The two counter electrodes 320 are arranged parallel to each other so that the discharge electrodes 310 are positioned between them. The distance between adjacent discharge electrodes 310 and counter electrodes 320 is, for example, 5.5 mm.

[0065] Furthermore, the exposed portion 326 of the counter electrode 320 is formed by a groove 327 (see Figure 10) that occurs between the two covering portions 322 that sandwich the conductive portion 321. The dimensions of the groove 327 formed in the counter electrode 320 are, for example, in Figure 7, 0.5 mm in width parallel to the thickness direction of the counter electrode 320 (= thickness t of the conductive portion 321) and 1.5 mm in depth d parallel to the ventilation direction f.

[0066] Figure 8 is a top view showing the discharge electrode 310 and counter electrode 320 of the charging section 3 according to the embodiment, and Figure 9 is a side view of the discharge electrode 310 and counter electrode 320 of the charging section 3 according to the embodiment as seen from the ventilation direction f. Figure 10 is a cross-sectional view taken along the line AA shown in Figure 8.

[0067] As shown in Figure 8 and other figures, the counter electrode 320 according to this embodiment has a rectangular parallelepiped conductive portion 321. In a plan view, the longitudinal direction (hereinafter also simply referred to as "longitudinal direction") of the main surface (first main surface 321a and second main surface 321b) of the conductive portion 321 is parallel to the extension direction of the discharge electrode 310.

[0068] Furthermore, in a plan view, the short-side direction (hereinafter also simply referred to as the "short-side direction") of the main surfaces (first main surface 321a and second main surface 321b) of the conductive portion 321 is perpendicular to the extension direction of the discharge electrode 310.

[0069] Furthermore, as shown in Figure 10, the conductive portion 321 is positioned such that the central part of the first main surface 321a (or second main surface 321b) is closest to the discharge electrode 310. In other words, the discharge electrode 310 is positioned such that the distance between the discharge electrode 310 and a pair of longitudinally aligned side surfaces 321c of the conductive portion 321 is greater than the distance between the discharge electrode 310 and the central part of the first main surface 321a (or second main surface 321b). In addition, the discharge electrode 310 is positioned such that the distance between the discharge electrode 310 and the pair of exposed side surfaces 321c of the conductive portion 321 is constant.

[0070] In this embodiment, as shown in Figure 10, the plate-shaped conductive portion 321 is sandwiched between the plate-shaped first covering portion 323 and the second covering portion 324 to form the counter electrode 320. This allows the counter electrode 320 to be easily formed in this embodiment.

[0071] Furthermore, in this embodiment, the counter electrode 320 is constructed using a sandwich structure in which a conductor is sandwiched between a pair of insulators, thereby forming an exposed surface 321c1 that is exposed to the side surface 321c of the conductive portion 321. This makes it possible to form an exposed portion 326 in a simple configuration that efficiently generates the phenomenon of electrons being ejected at high speed from inside the conductive portion 321 in the counter electrode 320 shown in Figure 5.

[0072] Therefore, according to this embodiment, the charging efficiency of the charging unit 3 can be increased with a simple configuration.

[0073] In addition, in this embodiment, a groove 327 may be formed in the counter electrode 320, with the exposed surface 321c1 of the conductive portion 321 as its bottom surface. Such a groove 327 is formed by the exposed surface 321c1 of the conductive portion 321, the surface 323a of the first covering portion 323 that faces the first main surface 321a of the conductive portion 321, and the surface 324a of the second covering portion 324 that faces the second main surface 321b of the conductive portion 321.

[0074] This ensures that the groove 327 has a depth d necessary to stably achieve intermittent discharge when the exposed portion 326 is formed in the groove 327. In other words, by forming the exposed portion 326 on the bottom surface of the groove 327 with depth d, it is possible to prevent discharge from occurring before sufficient charge has accumulated in the coating portion 322, and to stably generate pulsed discharge due to the charge accumulated in the coating portion 322. Therefore, according to this embodiment, the charged portion 3 can be operated stably.

[0075] Furthermore, in this embodiment, the exposed surface 321c1 may be formed on one of the multiple side surfaces 321c that aligns with the longitudinal direction. This allows the exposed surface 321c1 to be positioned without facing the discharge electrode 310, and also allows the exposed surface 321c1 to be positioned farther away from the discharge electrode 310, thereby further increasing the charging efficiency of the charging unit 3. Details of these effects will be described below.

[0076] The charging efficiency of the charging section 3 is proportional to the amount of charge and inversely proportional to the current flowing between the discharge electrode 310 and the counter electrode 320. This current is approximately proportional to the number of ions released from the counter electrode 320 per unit time.

[0077] Furthermore, the velocity of ions emitted from the exposed surface 321c1 varies depending on the electric field strength of the electric field formed in the exposed portion 326. The electric field strength of the electric field formed in the exposed portion 326 (i.e., the velocity of emitted ions) decreases as the distance between the exposed portion 326 and the discharge electrode 310 increases.

[0078] For example, in the configuration shown in Figure 7, the electric field strength of the electric field formed in the exposed portion 326 is approximately half that of the electric field strength of the electric field formed in the conductive portion 321 located directly below the discharge electrode 310.

[0079] Furthermore, even if the current flowing between the discharge electrode 310 and the counter electrode 320 is the same, by positioning the exposed surface 321c1 far away from the discharge electrode 310 instead of facing it, the electric field strength of the electric field formed in the exposed portion 326 can be reduced, thereby slowing down the velocity of the emitted ions. This allows a large number of ions (i.e., ions with high spatial density) to float in the space, and fine particles contained in the air passing through the space can be efficiently charged by these ions with high spatial density.

[0080] As described above, in this embodiment, the exposed portion 326 is formed on the longitudinal side 321c of the plurality of side surfaces 321c, allowing the exposed surface 321c1 to be positioned far from the discharge electrode 310 without facing it. As a result, in this embodiment, the spatial density of ions can be increased even when the current value flowing between the discharge electrode 310 and the counter electrode 320 is the same, compared to the case where the exposed surface 321c1 is positioned close to and facing the discharge electrode 310. Therefore, according to this embodiment, the charging efficiency of the charging portion 3 can be increased.

[0081] Furthermore, since the exposed surface 321c1 is formed on the side surface 321c that aligns with the longitudinal direction among the multiple side surfaces 321c, an exposed area 326 with sufficient area along the longitudinal direction of the conductive portion 321 can be provided. This suppresses variations in the discharge frequency depending on the longitudinal position of the exposed surface 321c1, and enables stable discharge regardless of the longitudinal position of the counter electrode 320 (conductive portion 321).

[0082] Furthermore, in the embodiment, as shown in Figure 9 and other figures, the covering portion 322 may have a third covering portion 325 in addition to the first covering portion 323 and the second covering portion 324 described above. Such a third covering portion 325 is made of an insulator. For example, insulating tape can be used for the third covering portion 325.

[0083] The third coating portion 325 covers the surface of the conductive portion 321, specifically the side surface 321c perpendicular to the extension direction of the discharge electrode 310 (i.e., the side surface 321c along the shorter direction).

[0084] As a result, the side surface 321c perpendicular to the extension direction of the discharge electrode 310 becomes the covered surface 321c2, and the exposed surface 321c1 is formed only on the side surface 321c that aligns with the longitudinal direction of the conductive portion 321 among the multiple side surfaces 321c.

[0085] Furthermore, by making the side surface 321c along the shorter direction the coated surface 321c2, it is possible to suppress unintended discharges from the side surface 321c along the shorter direction, which is located closer to the discharge electrode 310 than the side surface 321c along the longer direction and has a stronger electric field strength.

[0086] Furthermore, by designating the side surface of the conductive portion 321 that is parallel to the extension direction of the discharge electrode 310 (the side surface 321c along the longitudinal direction) as the exposed surface 321c1 (that is, only the side surface 321c along the longitudinal direction, where the distance from the discharge electrode 310 is constant, as the exposed surface 321c1), it is possible to generate a discharge almost uniformly from the entire exposed surface 321c1.

[0087] Therefore, according to this embodiment, the charging efficiency can be further increased, and the charging unit 3 can be operated stably.

[0088] <Various variations> Next, various modifications according to the embodiment will be described with reference to Figures 11 and 12. Figure 11 is a cross-sectional view showing the discharge electrode 310 and counter electrode 320 of the charging section 3 according to modification 1 of the embodiment, and corresponds to Figure 10 of the embodiment.

[0089] As shown in Figure 11, in Modification 1, the longitudinal side surface 321c of the conductive portion 321, the longitudinal side surface 323b of the first covering portion 323, and the longitudinal side surface 324b of the second covering portion 324 are arranged substantially flush with each other. As a result, in Modification 1, no groove 327 (see Figure 10) is formed in the exposed portion 326.

[0090] In the modified example 1, the counter electrode 320 is constructed using a sandwich structure in which a conductor is sandwiched between a pair of insulators, thereby forming an exposed surface 321c1 that is exposed to the side surface 321c of the conductive portion 321. As a result, the phenomenon of electrons rapidly escaping from inside the conductive portion 321 in the counter electrode 320 can be efficiently generated. Therefore, according to the modified example 1, an exposed portion 326 that enhances the charging efficiency of the charged portion 3 can be formed with a simple configuration.

[0091] Furthermore, in the modified example 1 shown in Figure 11, the exposed surface 321c1 can be positioned far away from the discharge electrode 310 without facing it. Therefore, similar to the embodiment shown in Figure 10, the spatial density of ions can be increased even when the current value flowing between the discharge electrode 310 and the counter electrode 320 is the same. Accordingly, according to the modified example 1, the charging efficiency of the charging section 3 can be increased.

[0092] Figure 12 is a cross-sectional view showing the discharge electrode 310 and counter electrode 320 of the charging section 3 according to a modified example 2 of the embodiment, and corresponds to Figure 10 of the embodiment.

[0093] As shown in Figure 12, in the modified example 2, of the pair of side surfaces 321c along the longitudinal direction of the conductive portion 321, the side surface 321c located on the upstream side in the ventilation direction f is covered by the fourth covering portion 328.

[0094] The fourth covering portion 328 is included in the covering portion 322 and is made of an insulator. For example, insulating tape can be used for the fourth covering portion 328.

[0095] In the modified example 2, the counter electrode 320 is constructed using a sandwich structure in which a conductor is sandwiched between a pair of insulators, thereby forming an exposed surface 321c1 that is exposed to the side surface 321c of the conductive portion 321. As a result, the phenomenon of electrons rapidly escaping from inside the conductive portion 321 of the counter electrode 320 can be efficiently generated. Therefore, according to the modified example 2, an exposed portion 326 that enhances the charging efficiency of the charged portion 3 can be formed with a simple configuration.

[0096] Furthermore, in Modification 2, a groove 327 is formed with the exposed surface 321c1 located downstream in the ventilation direction f as its bottom surface, thereby ensuring a depth d necessary for stable intermittent discharge in the exposed portion 326. Therefore, according to Modification 2, the charging portion 3 can be operated stably.

[0097] Furthermore, in the modified example 2, the side surface 321c located upstream in the ventilation direction f is covered by the fourth covering portion 328, thereby preventing dust contained in the passing air from adhering to the side surface 321c.

[0098] Furthermore, in the modified example 2 shown in Figure 12, the exposed surface 321c1 can be positioned far away from the discharge electrode 310 without facing it. Therefore, similar to the embodiment shown in Figure 10, the spatial density of ions can be increased even when the current value flowing between the discharge electrode 310 and the counter electrode 320 is the same. Accordingly, according to the modified example 2, the charging efficiency of the charging section 3 can be increased.

[0099] In the example shown in Figure 12, only the side surface 321c located upstream in the ventilation direction f is covered by the fourth covering portion 328. However, the disclosure is not limited to this example, and only the side surface 321c located downstream in the ventilation direction f may be covered by the fourth covering portion 328.

[0100] Although embodiments of the present application have been described above based on the drawings, these are merely examples, and various modifications and improvements can be made based on the knowledge of those skilled in the art.

[0101] For example, in the above embodiment, an example was shown in which the first covering portion 323, the second covering portion 324, and the third covering portion 325 of the covering portion 322 are configured as separate parts, but the present disclosure is not limited to such an example.

[0102] For example, the first covering portion 323, the second covering portion 324, and the third covering portion 325 of the covering portion 322 may be formed as a single unit. In this case, for example, by forming the entire covering portion 322 with insulating tape, the first main surface 321a, the second main surface 321b, and a part of the side surface 321c of the conductive portion 321 can be covered as a single unit.

[0103] Furthermore, although the above embodiment shows an example in which only the side surface 321c along the longitudinal direction of the conductive portion 321 is the exposed surface 321c1, this disclosure is not limited to such an example. For example, only the side surface 321c along the short direction of the conductive portion 321 may be the exposed surface 321c1, or both the side surface 321c along the longitudinal direction and the side surface 321c along the short direction may be the exposed surface 321c1. In this case as well, the exposed portion 326 that improves charging efficiency can be formed with a simple configuration.

[0104] Based on the embodiments described above, the following discharge device and electrostatic precipitator 2 can be realized. The following discharge device corresponds to the charging section 3 in the electrostatic precipitator 2.

[0105] (1) A discharge device comprising a discharge electrode 310, a counter electrode 320 positioned opposite the discharge electrode 310, and a voltage application unit (high-voltage power supply 30 for charging unit) for applying a voltage to the discharge electrode 310, wherein the counter electrode 320 has a conductive part 321 formed of a plate-shaped conductor and a covering part 322 formed of an insulator that covers the surface of the conductive part 321, the covering part 322 has a first covering part 323 and a second covering part 324, the conductive part 321 has a first main surface 321a covered by the first covering part 323, a second main surface 321b covered by the second covering part 324 and a side surface 321c, and an exposed surface 321c1 is formed on at least a part of the side surface 321c.

[0106] This configuration allows for increased charging efficiency of the charging unit 3 with a simple design.

[0107] (2) In the discharge device described in (1) above, a groove 327 is formed in the counter electrode 320 with the exposed surface 321c1 of the conductive portion 321 as the bottom surface.

[0108] With this configuration, in addition to the effects of (1) above, the charging unit 3 can be operated stably.

[0109] (3) In the above (2), the groove 327 is formed by the surface 323a of the first covering portion 323 that faces the first main surface 321a of the conductive portion 321, the surface 324a of the second covering portion 324 that faces the second main surface 321b of the conductive portion 321, and the exposed surface 321c1 of the conductive portion 321.

[0110] With this configuration, in addition to the effects of (2) above, the charging unit 3 can be operated stably.

[0111] (4) In any one of (1) to (3) above, the exposed surface 321c1 is formed parallel to the extension direction of the discharge electrode 310 in the discharge device.

[0112] With this configuration, in addition to the effect of any one of (1) to (3) above, the charging efficiency of the charging unit 3 can be further increased.

[0113] (5) In any one of (1) to (4) above, the conductive portion 321 is formed in the shape of a rectangular parallelepiped having a plurality of side surfaces 321c, and the exposed surface 321c1 is formed on the side surface 321c of the conductive portion 321 that is aligned with the longitudinal direction on the main surface of the conductive portion 321.

[0114] With this configuration, in addition to any one of the effects described in (1) to (4) above, the charging efficiency of the charging unit 3 can be further increased.

[0115] (6) In any one of (1) to (5) above, the conductive portion 321 is formed in the shape of a rectangular parallelepiped having a plurality of side surfaces 321c, and the covering portion 322 has a third covering portion 325 that covers the side surfaces 321c of the conductive portion 321 that are aligned with the shorter direction on the main surface of the conductive portion 321.

[0116] With this configuration, in addition to the effect of any one of the above (1) to (5), the charging unit 3 can be operated stably.

[0117] (7) An electrostatic precipitator 2 comprising one of the above (1) to (6) discharge devices (charging unit 3) and a dust collector (dust collector 4) that collects dust in the air that has been charged by the discharge device (charging unit 3).

[0118] With this configuration, an electrostatic precipitator 2 can be provided that achieves any one of the effects (1) to (6) described above.

[0119] The embodiments and specific names, processes, controls, and various data shown in the illustrations described above are merely examples and may be modified as appropriate.

[0120] Furthermore, broader aspects of the embodiments described above are not limited to the specific details and representative embodiments expressed and described above. Accordingly, various modifications are possible without departing from the overall concept or scope of the invention as defined by the appended claims and their equivalents. [Explanation of symbols]

[0121] 2. Electrostatic precipitator 3. Charging section (an example of a discharge device) 4. Dust collection section (an example of a dust collection device) 30. High-voltage power supply for the charging section (an example of a voltage application section) 310 Discharge electrode 320 Counter electrode 321 Conductive part 321a First main surface 321b 2nd principal surface 321c side 321c1 Exposed surface 321c2 coated surface 322 Covering part 323 First covering section 324 Second covering section 325 Third covering section 326 Exposed part 327 groove 328 Fourth covering section

Claims

1. Discharge electrode and A counter electrode positioned opposite the discharge electrode, A voltage application unit that applies a voltage to the discharge electrode, Equipped with, The aforementioned counter electrode is A conductive part formed from a plate-shaped conductor, A covering portion formed of an insulator that covers the surface of the conductive portion, It has, The covering portion has a first covering portion and a second covering portion. The conductive portion has a first main surface covered by the first covering portion, a second main surface covered by the second covering portion, and a side surface. An exposed surface is formed on at least a portion of the aforementioned side surface. The counter electrode is formed with a groove whose bottom surface is the exposed surface of the conductive portion. Discharge device.

2. The groove is formed by the surface in the first coating portion facing the first main surface of the conductive portion, the surface in the second coating portion facing the second main surface of the conductive portion, and the exposed surface of the conductive portion. The discharge device according to claim 1.

3. A discharge electrode and A counter electrode positioned opposite the discharge electrode, A voltage application unit that applies a voltage to the discharge electrode, Equipped with, The aforementioned counter electrode is A conductive part formed from a plate-shaped conductor, A covering portion formed of an insulator that covers the surface of the conductive portion, It has, The covering portion has a first covering portion and a second covering portion. The conductive portion has a first main surface covered by the first covering portion, a second main surface covered by the second covering portion, and a side surface. An exposed surface is formed on at least a portion of the aforementioned side surface. The conductive part is formed in the shape of a rectangular parallelepiped having multiple sides, The covering portion has a third covering portion that covers the side surface of the conductive portion that is aligned with the shorter direction of the main surface of the conductive portion. Discharge device.

4. The exposed surface is formed parallel to the extension direction of the discharge electrode. A discharge device according to any one of claims 1 to 3.

5. The conductive part is formed in the shape of a rectangular parallelepiped having multiple sides, The exposed surface is formed on the side surface of the conductive portion that is aligned with the longitudinal direction of the main surface of the conductive portion. A discharge device according to any one of claims 1 to 4.

6. A discharge device according to any one of claims 1 to 5, A dust collector that collects dust in the air charged by the aforementioned discharge device, An electrostatic precipitator equipped with the following features.

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