JP7534081B2 - Electrostatic precipitators and air purifiers - Google Patents

Description

The present invention relates to an electric dust collector that collects polluting particles (dust) in dust, smoke, and oily smoke in the air by charging them with a corona discharge generated by applying a high voltage, and an air purifier equipped with the electric dust collector.

Conventionally, devices that purify the air by sucking in dust have been widely used. For example, Patent Document 1 discloses an air purifier that has a discharge electrode and a liquid tank in a dust collection tube, generates a corona discharge by applying a high voltage between the discharge electrode and the water stored in the liquid tank, and atomizes the water in the liquid tank with an agitation means, thereby collecting dust, dirt, and other contaminant particles in the air into the water in the liquid tank.

JP 2006-102651 A (see, in particular, embodiment 3 and FIG. 4)

However, in the air purifier described in Patent Document 1, the air flow passage from the suction port of the dust collector to the exhaust port is formed horizontally and linearly along the water surface of the liquid tank, while the atomized liquid particles (hereinafter referred to as "mist") from the liquid tank scatter from the bottom to the top. Therefore, in the air flow passage through which the contaminant particles (hereinafter referred to as "dust") pass (particularly the upper part of the air flow passage), there is a possibility that the degree of contact with the atomized mist is low, resulting in an area where mixing is difficult. In addition, if the air purifier described in Patent Document 1 is used in, for example, a smoke separator, if particles such as sparks flow in from the suction port, there is a risk that the particles such as sparks will flow out from the exhaust port as is, creating a risk of fire.

Furthermore, the stirring means is disposed downstream of the discharge electrode in the air flow direction, and since the dust is charged but the mist is not, the charged dust and uncharged mist are mixed together. Therefore, the area around the mist does not become a charged area, and the dust is not attracted to the mist, making it impossible to improve charging (electrostatic) performance.

The present invention has been made to solve the above problems, and aims to provide an electric dust collector and air purifier that improves the degree of contact between dust and mist passing through the air flow passage, thoroughly mixes the two, and charges them, thereby improving charging (electrostatic charge) performance, while also being safe and free of the risk of fire.

To achieve the above-mentioned object, the first electrostatic precipitator of the present invention is an electrostatic precipitator that collects dust particles in the air by charging them with corona discharge generated by applying a high voltage, and is characterized by comprising a liquid tank for storing a conductive liquid, a discharge electrode arranged at a fixed distance from the liquid surface of the liquid tank, a suction port provided at a position facing the liquid surface of the liquid tank, and a mist generating unit that mistifies the liquid in the liquid tank toward the suction port.

According to the first electrostatic precipitator of the present invention, the mist generated by the mist generation unit scatters toward the suction port through which the airflow passes, and the entire inside of the suction port can be filled with mist particles. In addition, since the mist scatters in the opposite direction to the airflow, the degree (ratio) of mixing with the dust in the air flowing in from the suction port can be increased. Furthermore, the mist retains its charge by being charged, and dust is attracted to the mist by forming a charged area around it. Therefore, charging (electrostatic) performance can be improved. In addition, since the mist scatters throughout the inside of the suction port, there is no risk of fire even if sparks or other particles flow in from the suction port, and safety can be improved.

The second electrostatic precipitator of the present invention is characterized in that in the above-mentioned first electrostatic precipitator, the mist generating unit is equipped with an ultrasonic vibrator, and the ultrasonic vibrator is in contact with the liquid in the liquid tank in a position facing the liquid surface side of the liquid tank.

The second electrostatic precipitator of the present invention uses an ultrasonic vibrator that can atomize liquids at low cost, improving economy. In addition, ultrasonic vibrators can atomize liquids quickly, and can generate mist from the moment the power is turned on. Furthermore, ultrasonic vibrators consume little electricity, reducing running costs.

The third electrostatic precipitator of the present invention is the second electrostatic precipitator described above, characterized in that a hole is formed in the bottom of the liquid tank at a position corresponding to the center of the suction port, and the ultrasonic vibrator is provided at a position corresponding to the hole.

According to the third electrostatic precipitator of the present invention, mist is generated from the liquid surface corresponding to the center of the suction port (airflow), so the mist can be dispersed evenly throughout the entire inside of the suction port.

The fourth electrostatic precipitator of the present invention is the first electrostatic precipitator described above, characterized in that the mist generating unit includes a heater, and the heater is disposed in the liquid tank facing the liquid surface side of the liquid tank.

According to the fourth electrostatic precipitator of the present invention, the liquid in the liquid layer can be heated by a heater to destroy (sterilize) bacteria and viruses in the liquid, thereby purifying the mist that is generated.

The fifth electrostatic precipitator of the present invention is any one of the first to fourth electrostatic precipitators described above, characterized in that the liquid tank is provided with a porous liquid absorbing member that absorbs and holds conductive liquid, the liquid absorbing member is disposed in the liquid tank so that a liquid film is formed above the liquid absorbing member, and an opening is provided in the area corresponding to the mist generating section.

According to the fifth electrostatic precipitator of the present invention, the liquid suction member can suppress the generation of waves on the liquid surface in the liquid tank, and a stable discharge can be performed by forming a liquid film. In addition, since the liquid in the liquid tank is stored in the opening, a stable mist can be generated by the mist generation unit.

The sixth electrostatic precipitator of the present invention is the fifth electrostatic precipitator described above, characterized in that the opening of the liquid suction member is formed within an area facing the suction port.

According to the sixth electrostatic precipitator of the present invention, the liquid suction member does not adversely affect the suppression of the generation of waves on the liquid surface.

The seventh electrostatic precipitator of the present invention is the sixth electrostatic precipitator described above, characterized in that the suction port is provided with a straightening plate with a large number of holes formed therein, and a roof is provided above the opening of the liquid suction member between the straightening plate and the liquid surface of the liquid tank, and the roof is formed in an umbrella shape that slopes downward from a position corresponding to the center of the suction port toward the liquid tank.

According to the seventh electrostatic precipitator of the present invention, the roof can prevent the liquid in the liquid tank from becoming dirty and can also prevent dust from accumulating on the upper surface of the roof.

The eighth electrostatic precipitator of the present invention is any one of the first to seventh electrostatic precipitators described above, characterized in that the discharge electrodes are arranged in multiple numbers around the downstream end of the suction port in the air flow direction.

According to the eighth electrostatic precipitator of the present invention, by arranging the discharge electrode downstream of the suction port close to the mist generating section, the dust and mist can be charged while they are kept mixed, thereby improving the charging performance.

The ninth electrostatic precipitator of the present invention is any one of the first to eighth electrostatic precipitators described above, characterized in that the discharge electrode has a bundled portion in which wire electrodes made of conductive fibers are bundled, and the tip of the discharge electrode is arranged toward the liquid surface of the liquid tank.

According to the ninth electrostatic precipitator of the present invention, by forming the discharge electrode into a bundle-shaped portion, it is possible to make it resistant to dirt and improve durability. In addition, since a corona discharge can be generated at a low voltage, it is possible to suppress the generation of waves on the liquid surface and perform a stable discharge. Furthermore, by arranging the tip of the discharge electrode toward the liquid surface, a stable discharge can be performed between the discharge electrode and the liquid surface.

The tenth electrostatic precipitator of the present invention is the ninth electrostatic precipitator described above, characterized in that the bundle of the discharge electrode is composed of 10 to 200 wire electrodes, each having a diameter of 5 to 25 μm, bundled together.

The tenth electrostatic precipitator of the present invention can improve circulation and economy, as well as durability (resistance to rust) and discharge (charging) performance.

The eleventh electrostatic precipitator of the present invention is any one of the first to tenth electrostatic precipitators described above, characterized in that it includes a housing having an internal space, the liquid tank is disposed within the housing, the housing is provided with a suction port at a position facing the liquid surface above the liquid tank, and an air flow passage is formed downstream of the suction port in the air flow direction so that air flowing into the housing from the suction port is diffused around the liquid tank along the liquid surface of the liquid tank.

According to the eleventh electrostatic precipitator of the present invention, by changing the direction of the airflow from a downward direction to a horizontal direction, large particles contained in the air are separated from the airflow and collected in the liquid tank, so that dirt on the discharge electrode and the repulsion part can be reduced and durability can be improved. In addition, the air flowing in from the suction port flows so as to be diffused from the suction port to the surrounding liquid surface, so that the entire liquid surface of the liquid tank can be effectively utilized. Furthermore, by making a passage between the housing and the liquid tank, the internal space of the housing can be effectively utilized.

The air purifier of the present invention is an air purifier equipped with any one of the electrostatic precipitators 1 to 11 described above, characterized in that the electrostatic precipitator and a suction fan are housed inside a case, an intake port is opened at the top of the case, and an exhaust port is opened at the bottom of the case.

The air purifier of the present invention can improve dust collection (capture) performance. In particular, it is effective in preventing fires caused by sparks, etc., and is therefore suitable for use in smoke separators.

The present invention can provide a variety of excellent effects, such as improving the degree of contact between dust and mist passing through the air flow passage, thoroughly mixing and charging the two to improve charging (electrostatic charge) performance, and providing an electric dust collector and air purifier that are safe and free of fire hazards.

1 is a perspective view showing an electric dust collector according to an embodiment of the present invention, viewed obliquely from above. 1 is a perspective view showing the inside of an electric dust collector according to an embodiment of the present invention, viewed obliquely from above. 1 is a side cross-sectional view showing an electric dust collector according to an embodiment of the present invention, cut in the left-right direction from a center position in the front-rear direction. 1 is a side cross-sectional view showing a side portion of an electric dust collector according to an embodiment of the present invention, taken in the left-right direction from a center position in the front-rear direction. 1 is an exploded perspective view showing an upper portion of an electric dust collector according to an embodiment of the present invention, viewed obliquely from below. 1 is a perspective view showing an electric dust collector according to an embodiment of the present invention, viewed obliquely from below. 1 is a perspective view showing an atomization device of an electric dust collector according to an embodiment of the present invention, viewed obliquely from above. This is a cross-sectional view taken along the line XX in FIG. 7. 1 is a perspective view showing an air purifying device according to an embodiment of the present invention.

Hereinafter, the embodiments of the present invention will be described with reference to the attached drawings. Note that each embodiment described below is a preferred specific example of the present invention, and may have various technically preferable limitations, but the technical scope of the present invention is not limited to these aspects unless there is a particular description that limits the present invention.
[Electrostatic Precipitator According to the First Embodiment]

First, an electric dust collector according to an embodiment of the present invention will be described with reference to Figs. 1 to 8. Fig. 1 is a perspective view of an electric dust collector according to an embodiment of the present invention, viewed obliquely from above. Fig. 2 is a perspective view of the inside of an electric dust collector according to an embodiment of the present invention, viewed obliquely from above. Fig. 3 is a side cross-sectional view of an electric dust collector according to an embodiment of the present invention, cut in the left-right direction from the center position in the front-rear direction. Fig. 4 is a side cross-sectional view of a side portion of an electric dust collector according to an embodiment of the present invention, cut in the left-right direction from the center position in the front-rear direction. Fig. 5 is an exploded perspective view of an upper portion of an electric dust collector according to an embodiment of the present invention, viewed obliquely from below. Fig. 6 is a perspective view of an electric dust collector according to an embodiment of the present invention, viewed obliquely from below. Fig. 7 is a perspective view of an atomizing device of an electric dust collector according to an embodiment of the present invention, viewed obliquely from above. Fig. 8 is a cross-sectional view taken along the line X-X of Fig. 7.

For ease of explanation, in the following explanation, the directions in each figure are set based on the front-back, left-right, and up-down directions indicated by the arrows in Figure 1. Furthermore, "flow direction" refers to the direction in which air flows, and "upstream" and "downstream" and similar terms refer to "upstream" and "downstream" in the air flow direction, and similar concepts.

An electrostatic precipitator 1 according to an embodiment of the present invention is a device that collects particles in the air by charging them with a corona discharge, and is configured to include a housing 2, a liquid tank 3, an atomizing device 60, a discharge unit 4, a power supply insulator 5, a support insulator 6, and a high-voltage power supply unit 7. The housing 2 serves as a ground electrode connected to a reference potential point (e.g., the earth). The liquid tank 3 is provided inside the housing 2 and is supported by the housing 2 via the power supply insulator 5 and the support insulator 6. The discharge unit 4 includes a discharge electrode 30 that generates a corona discharge between the discharge unit 4 and the liquid surface of the liquid tank 3.
<Case>

The housing 2 is formed in a flat rectangular parallelepiped shape with an internal space. A rectangular top plate 11 is fixed to the top surface of the housing 2. The top plate 11 is detachably attached to the housing 2 with a total of eight screws 12 via bent portions 8 formed on the upper edges of each of the side surfaces 2a, 2b, 2c, and 2d of the housing 2. A rectangular riser portion 13 is formed in the center of the top plate 11 in a plan view. An intake port 15 is fixed inside the riser portion 13, and a rectangular opening portion 14 is also formed therein.

The suction port 15 has an upper portion 16 formed in a rectangular tubular shape along the inner surface of the rising portion 13, and a lower portion 18 formed in a rectangular tubular shape via an inclined portion 17 that slopes downward and inward from the upper portion 16, and the lower portion 18 is formed with a smaller diameter than the upper portion 16. An suction port duct 51 is connected to the upper portion 16 of the suction port 15.

A straightening plate 9 is provided horizontally inside the upper portion 16 of the suction port 15 in a direction that blocks the flow of air. A large number of holes 19 are formed in the straightening plate 9, and the opening area of the holes 19 is set to gradually increase from the center to the outer periphery. This allows the internal space of the suction port 15 to be used effectively, and by reducing the amount of air flowing through the center of the suction port 15 and increasing the amount of air flowing through the outer periphery of the suction port 15, the charging efficiency can be improved.

A rectangular base plate 21, smaller than the top plate 11, is fixed to the bottom of the top plate 11 via a total of four spacers 20. A rising portion 22 is formed in the center of the base plate 21 at a position corresponding to the rising portion 13 of the top plate 11. The upper end of the rising portion 22 contacts the underside of the top plate 11, and an opening 23 of the same shape as the opening 14 is formed inside the rising portion 22 at a position corresponding to the opening 14.

A rectangular ring-shaped support fixing member 24 is formed on the underside of the base plate 21 at a position facing the opening 23, and a rectangular ring-shaped repulsion portion 25 is formed on the radially outer side of the support fixing member 24 so as to surround the support fixing member 24. The support fixing member 24 has a U-shaped cross section with an open upper surface, and the inner surface 24a of the support fixing member 24 forms the same surface as the inner surfaces of the rising portions 13 and 22.

The repulsive portion 25 has a U-shaped cross section with an open upper surface, and is disposed at a predetermined distance X (see FIG. 4) outside the support fixing member 24. The repulsive portion 25 is longer in both the radial and vertical directions than the support fixing member 24, and a conductive flat portion 26 is formed on the lower surface of the repulsive portion 25.

A rectangular exhaust port 50 is formed on the bottom surface of the housing 2. In order to prevent a decrease in pressure loss in the air flow passage 27, the opening area of the exhaust port 50 is set to be larger than the opening area of the suction port 15. An exhaust duct 52 is connected to the exhaust port 50, and a suction fan 55 is provided in the exhaust duct 52. The suction fan 55 is electrically connected to the control unit 70 and is controlled based on a command from the control unit 70. In this embodiment, the suction port duct 51 and the exhaust duct 52 are connected to the suction port 15 and the exhaust port 50, respectively, but air may be sucked from the periphery of the exhaust port 50 and exhausted to the periphery of the exhaust port 50 without using the ducts 51 and 52.
<Liquid tank>

The liquid tank 3 is supported by the housing 2 via the power supply insulator 5 and the support insulator 6. The liquid tank 3 is stored inside the housing 2, and an air flow passage 27 is formed around the liquid tank 3. The liquid tank 3 is formed in a flat rectangular shape with an open top, and a circular hole 54 is formed in the bottom of the liquid tank 3 at a position corresponding to the center of the suction port 15.

A conductive liquid 28 (e.g., water) is stored in the liquid tank 3. The liquid stored in the liquid tank 3 may be a liquid containing a bactericidal component that kills viruses and the like, or a deodorizing component. A water level sensor (not shown) that monitors the water level in the liquid tank 3 is provided in the liquid tank 3, and when the water level in the liquid tank 3 becomes low, liquid is supplied from a water storage section (not shown) to the liquid tank 3 by a pump (not shown) or the like. This ensures that the water level of the liquid in the liquid tank 3 is always maintained at an appropriate level.

Inside the liquid tank 3, there is provided a liquid absorbing member 29 made of a porous material that has the absorbency (water absorption) to absorb and hold the conductive liquid. Here, a porous material refers to a material in which spaces (gaps between fibers, foam, etc.) are formed within the material and liquid can permeate through it; specifically, it may be a foam material, a sponge, a gel, or a metal material.

A cylindrical opening 53 is formed in the center of the liquid suction member 29. The opening 53 is formed in a region facing the suction port 15, and the opening area of the opening 53 is set to be smaller than the opening area of the suction port 15. In this embodiment, the opening 53 is circular in plan view, but it may be rectangular or elliptical.

The thickness of the liquid absorbing member 29 around the opening 53 is set to be approximately equal to the thickness from the top of the liquid tank 3 to the bottom of the liquid tank 3, so that when contained in the liquid tank 3, a liquid film of, for example, 0.5 mm or less is formed on the upper surface of the liquid absorbing member 29. The liquid absorbing member 29 around the opening 53 may be formed in a thin plate shape and placed only on the upper part of the liquid tank 3. In that case, a mesh-shaped support (not shown) is attached to the lower side of the liquid absorbing member 29 in the liquid tank 3 to support the liquid absorbing member 29, and liquid (for example, water) is stored below the support.

The liquid suction member 29 absorbs dirt over the course of operating time and gradually becomes dirty. When this happens, the dirty liquid suction member 81 can be removed from the liquid tank 3 and cleaned or replaced. This eliminates the need for equipment to drain wastewater from the liquid tank 3, making it highly economical.

Also, as shown by the two-dot chain line in FIG. 3, a roof 57 may be provided between the straightening plate 9 and the liquid tank 3 in the internal space of the suction port 15. The roof 57 is disposed opposite the straightening plate 9 so that a flow path is formed around it, and is set to the same size and shape as the opening 53 of the liquid suction member 29 in a plan view. By providing the roof 57, dust in the air that flows in from the suction port 15 is collected by the liquid suction member 29 rather than in the liquid at the opening 53, so that the liquid in the liquid tank 3 can be prevented from becoming dirty.

3, the roof 57 may be formed in an umbrella shape inclined downward from a position corresponding to the center of the suction port 15 toward the liquid tank 3, thereby making it difficult for dust to accumulate on the upper surface of the roof 57. Furthermore, the air flowing in from the suction port 15 can be guided in the outer circumferential direction of the suction port 15, thereby improving the charging efficiency (electrostatic charging efficiency). The shape of the roof 57 is not limited to an umbrella shape, and may be a flat plate shape, or instead of the roof 57, the hole 19 in the straightening plate 9 facing the opening 53 of the liquid suction member 29 may be closed.
<Atomization device>

As shown in FIG. 3, the mist generating device 60 is composed of a mist generating unit 61 provided at a position corresponding to the hole 54, and an oscillator unit 62 having an oscillator circuit (transmitter board), and the mist generating unit 61 and the oscillator unit 62 are connected to the control unit 70 by a cable 63. Note that in this embodiment, the mist generating unit 61 and the oscillator unit 62 are separate, but they may be integrated.

As shown clearly in Figures 7 and 8, the mist generating unit 61 includes a transducer case 64 and an ultrasonic transducer 65 supported by the transducer case 64. The transducer case 64 is composed of a plate-shaped main body 66 and a disk-shaped base 67 protruding from the center of the upper surface of the main body 66. The ultrasonic transducer 65 is formed from a thin circular plate material, for example made of stainless steel (SUS316), and is fixed facing upwards to the upper surface of the base 67. Note that the ultrasonic transducer 65 may be a piezoelectric transducer in which metal electrodes are plated on both sides of a piezoelectric ceramic plate.

A gasket 68 is provided around the ultrasonic vibrator 65, and the gasket 68 is formed cylindrically so that it can abut against the bottom around the hole 54 on the upper surface of the base 67. The mist generating unit 61 is fixed to the bottom of the liquid tank 3 by fixing screws 69 screwed into the front and rear ends of the main body 66, and the ultrasonic vibrator 65 is arranged so as to contact the liquid in the liquid tank 3 with its orientation facing the liquid surface side of the liquid tank 3. In addition, the mist generating unit 61 is tightly attached to the bottom of the liquid tank 3 by the gasket 68, so there is no risk of the liquid in the liquid tank 3 leaking out.

In this embodiment, the transducer case 64 is fixed to the bottom of the liquid tank 3, but a float (not shown) may be attached to the transducer case 64 and immersed in the liquid in the liquid tank 3. The float follows the up and down movements of the liquid surface, so it does not interfere with the generation of mist.

The oscillator 62 is electrically connected to the control unit 70 and is controlled based on commands from the control unit 70. The ultrasonic transducer 65 vibrates at a frequency of several MHz (e.g., 2.4 MHz) output from the oscillator 62.

As another embodiment of the atomizing device 60, a heating (steam) device may be used to supply mist. For example, as shown by the two-dot chain line in FIG. 3, the heater 56 may be disposed in the liquid tank 3 several mm below the liquid surface, facing the liquid surface. By heating the liquid with the heater 56, bacteria and viruses in the liquid can be destroyed (sterilized), and the generated mist is also purified, making this suitable for an air purifying device. In this case, a liquid supplying means (not shown) may be provided to quantitatively supply the liquid required for the heater 56 to generate the mist.
<Discharge section>

As shown in FIG. 4, the discharge section 4 includes a plurality of discharge electrodes 30 and a support 31 that supports each discharge electrode 30. Each discharge electrode 30 includes a bundle 33 formed in a brush shape by bundling fibrous wire electrodes 32. The wire electrodes 32 are formed of non-magnetic stainless steel fibers with a diameter of 12 μm. This makes it easier for the wire electrodes 32 to separate from the bundle 33, improving the discharge performance. For example, in a magnetic ferrite system, the wire electrodes 32 are difficult to separate from the bundle 33, so the effect of electric field interference with the bundle is large, making it difficult to generate a corona discharge with a strong electric field. For example, one discharge electrode 30 is formed by bundling about 100 wire electrodes 32. The discharge electrode 30 may be formed by bundling 10 to 200 wire electrodes 32 with a diameter of 5 to 25 μm.

The voltage applied to the discharge electrode 30 is in the range of 4 to 6 kV, and the length of the discharge electrode 30 is in the range of 3 to 7 mm. Therefore, stable discharge is possible even at a relatively low voltage. In addition, a negative high voltage is applied to the discharge electrode 30 in the form of a direct current. By adopting a direct current method in this way, a relatively simple configuration can be achieved compared to other methods (alternating current, pulse). In addition, by adopting a negative charging method, a larger discharge current can be passed through the discharge electrode 30 in the same space (gap) compared to a positive charging method. Furthermore, discharge stability (characteristics that make it less likely to cause abnormal discharge) can be improved compared to a positive charging method.

The support 31 is made of stainless steel (SUS304), the same material as the wire electrode 32. The wire electrode 32 fixed to the support 31 and the support 31 are made of the same material (stainless steel), which prevents electrolytic corrosion (electrochemical corrosion) caused by contact between dissimilar metals.

The supports 31 are fixed in two rows in the circumferential direction on both the inner surface 24a and the outer surface 24b of the support fixing member 24. As a result, the multiple discharge electrodes 30 are arranged around the suction port 15, and the charging efficiency can be improved by arranging the supports 31 in two rows.

The multiple discharge electrodes 30 are provided extending downward from the support 31 toward the liquid surface of the liquid tank 3. All of the multiple discharge electrodes 30 are formed to have approximately the same overall length, and the tips of the multiple discharge electrodes 30 are approximately aligned. The multiple discharge electrodes 30 are provided intermittently at a predetermined pitch along the circumferential direction of the support 31.

The distance Y between the tip (lower end) of the discharge electrode 30 and the liquid surface in the liquid tank 3 is set to the same distance as the distance between the flat surface 26 of the repulsion portion 25 and the liquid surface in the liquid tank 3, and is set to several tens of mm at an applied voltage of several kV, for example. Note that, in order to improve collection performance (collection efficiency), the distance between the repulsion portion 25 and the liquid surface in the liquid tank 3 may be set closer than the distance Y between the tip of the discharge electrode 30 and the liquid surface in the liquid tank 3.

The distance X between the inner surface 25a of the repulsion portion 25 and the outer discharge electrode 30 is set to be greater than the distance Y (discharge distance) between the tip (lower end) of the discharge electrode 30 and the liquid surface of the liquid tank 3. This makes it possible to prevent electric field interference.

In addition, the lower end of the suction port 15 extends further toward the liquid surface than the tip (lower end) of the discharge electrode 30. As a result, the air flowing in from the suction port 15 is guided to flow along the liquid surface of the liquid tank 3 when it flows out from the suction port 15, so that the air does not flow to the base (upper part) of the discharge electrode 30, and the air passes through the charging area EA reliably, improving the charging performance (charging performance). Furthermore, as described above, the suction port 15 is formed so as to be separated from the discharge electrode 30 by the inclined part 17 of the suction port 15, so that electric field interference can be prevented. The distance between the lower part 18 of the suction port 15 and the inner discharge electrode 30 is set to be equal to the distance X between the inner surface 25a of the repulsion part 25 and the outer discharge electrode 30. This makes it possible to prevent electric field interference.
<Power supply insulators and support insulators>

One power supply insulator 5 and three support insulators 6 are provided between the side of the housing 2 and the side of the liquid tank 3. The power supply insulator 5 and the support insulators 6 are made of, for example, porcelain, ceramic, or resin with excellent electrical insulation properties.

The power supply insulator 5 includes an insulator body 34 that is interposed between one side surface 2a of the housing 2 and one side surface 3a of the liquid tank 3, and a power supply connection portion 35 that is provided on the outside of one side surface 2a of the housing 2. The insulator body 34 is formed in a substantially cylindrical shape, and a through hole 38a is formed in the axis of the insulator body 34.

The power supply connection portion 35 is composed of a disk-shaped flange portion 37 and a cylindrical recess portion 36 that is concentric with the flange portion 37 and has a smaller diameter than the flange portion 37. A through hole 38b is formed in the axis of the flange portion 37 so as to communicate with the through hole 38a of the insulator body 34. The insulator body 34 is fixed between one side surface 2a of the housing 2 and one side surface 3a of the liquid tank 3 by fastening a nut 40 to a power supply screw 39 that is inserted through the through hole 38b of the flange portion 37 and the through hole 38a of the insulator body 34.

A number of (four in the figure) fixing holes are formed at equal intervals around the circumference of the flange 37, and the power supply connection part 35 is fixed to one side surface 2a of the housing 2 by fastening nuts 42 to fixing screws 41 inserted into these fixing holes. A power supply spring 43 is provided in the recess 36 of the power supply connection part 35 so as to be in electrical contact with the power supply screw 39, and the power supply spring 43 is in electrical contact with the high voltage power supply part 7.

The supporting insulators 6 are respectively interposed between the three side surfaces 2b, 2c, 2d other than the side surface 2a of the housing 2 and the three side surfaces 3b, 3c, 3d other than the side surface 3a of the liquid vat 3. Through grooves 44a, 44b are formed from the inside and outside at the axis of the supporting insulator 6. By fastening fixing screws 45 into the through grooves 44a, 44b from the inside and outside of the supporting insulator 6, the supporting insulator 6 is fixed between the three side surfaces 2b, 2c, 2d of the housing 2 and the three side surfaces 3b, 3c, 3d of the liquid vat 3.
<High voltage power supply section>

3, the high-voltage power supply unit 7 includes a high-voltage transformer 46, a voltage multiplier 47, and a limit switch 48. The high-voltage power supply unit 7 is electrically connected to the control unit 70, and applies a high voltage to the liquid tank 3 side through the power supply insulator 5 based on the command of the control unit 70. The high-voltage transformer 46 boosts the AC voltage of the original power source P (AC 100V). The voltage multiplier 47 converts the AC voltage boosted by the high-voltage transformer 46 into a DC voltage and further boosts it to generate a high voltage of about minus 5 kV. The voltage multiplier 47 also functions as an output control unit that controls the application of a high voltage to the discharge electrode 30. The limit switch 48 is turned on (ON) when the electric dust collector 1 is attached to the air purifier 100 described later, and is turned off (OFF) when the electric dust collector 1 is removed from the air purifier 100.

If the dust collection method were a positive charging method, the discharge distance would have to be close to ensure the discharge current required for charging, making it easier for abnormal discharge to occur. Therefore, in the above-mentioned embodiment, the negative charging method is adopted in consideration of the fact that the discharge current is large even with the same spatial interval (gap) and the discharge stability (tendency to prevent abnormal discharge). A DC main power source (e.g. 24 V) may also be used.
<Air flow passage>

As shown by the arrows in Figures 3 and 4, inside the electrostatic precipitator 1, air that flows in from the central suction port 15 and descends is diffused outward along the liquid surface of the liquid tank 3, and then passes between the sides 2a, 2b, 2c, and 2d of the housing 2 and the sides 3a, 3b, 3c, and 3d of the liquid tank 3, and between the bottom of the housing 2 and the bottom of the liquid tank 3, and is discharged to the outside through the exhaust port 50. In this embodiment, the air flow path 27 is formed so that air is sucked in from the top of the electrostatic precipitator 1 and exhausted from the bottom, but the air flow may be reversed. In that case, the arrangement of the discharge electrode 30 and the repulsion portion 25 is also reversed.
[Function of the electric dust collector]

Next, the operation of the electrostatic precipitator 1 will be described with reference mainly to FIGS.
When the operation of the electrostatic precipitator 1 is started after confirming in advance by a water level sensor that the water level in the liquid tank 3 is at an appropriate level, the atomizing device 60 operates, a high voltage is applied to the discharge electrode 30, and the suction fan 55 rotates. As a result, dust-laden air containing dust generated outside the electrostatic precipitator 1 is sucked into the inside of the suction port 15 by the suction force of the suction fan 55 and becomes a descending air current (downflow), which flows into the housing 2 from the lower part 18 of the suction port 15.

At this time, the opening area of the holes 19 of the straightening plate 9 inside the suction port 15 is set to gradually increase from the center to the outer periphery, so that the internal space of the suction port 15 can be effectively utilized, and the amount of air flowing through the center of the suction port 15 can be reduced and the amount of air flowing through the outer periphery of the suction port 15 can be increased. This allows the air flowing into the housing 2 from the suction port 15 to be guided toward the periphery of the suction port 15 where the discharge electrode 30 is located without directly colliding with the liquid surface of the liquid tank 3 or ruffling the liquid surface, thereby improving charging efficiency.

The dust-laden air that flows into the housing 2 from the suction port 15 in this way spreads around the suction port 15 along the liquid surface of the liquid tank 3, because the inner diameter of the suction port 15 is larger than the inner diameter of the liquid tank 3, and passes between the discharge electrode 30 and the liquid surface of the liquid tank 3. By changing the direction of the dust-laden air flow from a downward direction to a horizontal direction, dust particles with large particle diameters contained in the dust-laden air are separated from the air flow and collected by the liquid suction member 29 in the liquid tank 3.

During this time, as shown clearly in FIG. 4, the ultrasonic vibrator 65 radiates high frequency waves of several MHz upward (vertically) from the bottom of the liquid tank 3 toward the liquid, causing ultrasonic vibration of the liquid and generating a liquid column 71. On the surface of the liquid column 71, the liquid atomizes to generate a mist of several μm (e.g., about 3 μm), which scatters around the liquid column 71. The mist generated at this time has a very fine particle size and is scattered in the opposite direction (upward) to the airflow direction (downward), so it mixes well with the small particle size dust contained in the dust-laden air inside the suction port 15.

In addition, in the discharge section 4, a high voltage is applied from the high voltage power supply section 7 to the liquid tank 3 side via the power supply insulator 5, creating a strong electric field in the line electrode 32 separated from the bundle section 33, and a corona discharge occurs between the tip of the line electrode 32 and the liquid tank 3. The corona discharge forms a roughly conical charged area EA between the tip of each discharge electrode 30 and the liquid surface of the liquid tank 3, charging the dust and mist with small particle diameters in the air flowing through the charged area EA. The mist retains its charge by being charged, and the area around the mist becomes a charged area, attracting dust, improving charging performance.

In this case, since the charged mist particles are charged with the same polarity (negative in this embodiment), they repel each other and do not merge together to form larger particles. This makes them easy to scatter and mix well with the dust in the dust-laden air. In addition, since the discharge unit 4 is located around the suction port 15 immediately downstream of the suction port 15 where the mist and dust are mixed, even mist with very fine particle diameters can be reliably charged without evaporating in a short time. The dust and mist charged in this way are attracted to the liquid surface of the liquid tank 3 and collected by the liquid suction member 29.

The dust-laden air that passes between the discharge electrode 30 and the liquid surface of the liquid tank 3 passes between the flat surface 26 of the repelling portion 25 and the liquid surface of the liquid tank 3. During this time, the charged dust and mist in the dust-laden air are repelled by the flat surface 26 of the repelling portion 25, and are attracted to the liquid surface side of the liquid tank 3 and collected by the liquid suction member 29.

The clean air from which dust has been removed by passing between the repulsion portion 25 and the liquid surface of the liquid tank 3 rises once from the outer periphery of the liquid tank 3, then descends, passing between the sides 2a, 2b, 2c, and 2d of the housing 2 and the sides 3a, 3b, 3c, and 3d of the liquid tank 3, and between the bottom of the housing 2 and the bottom of the liquid tank 3, before being discharged to the outside through the exhaust port 50.

At this time, the power supply insulator 5 and the support insulator 6 are each provided in the area downstream of the repulsion section 25 in the air flow direction where clean air flows (between the sides 2a, 2b, 2c, and 2d of the housing 2 and the sides 3a, 3b, 3c, and 3d of the liquid tank 3), so that defects such as creeping discharges and short-circuiting of high-voltage currents due to particle contamination adhering to the insulator surface and reducing insulation can be prevented.

As described above, in the electrostatic precipitator 1 according to the embodiment of the present invention, by using the ultrasonic vibrator 65 that can turn the liquid into mist immediately after operation, the operation of the atomizing device 60, the application of high voltage to the discharge unit 4, and the operation of the suction fan 55 can be started simultaneously. Therefore, the operation of the electrostatic precipitator 1 can be started immediately, and there is no need to set a standby time until the operation time. Therefore, the operating efficiency of the electrostatic precipitator 1 can be improved. In addition, by using the ultrasonic vibrator 65 as a means for generating mist, electricity consumption can be reduced, improving economy.

When the amount of air being sucked in or the amount of dust is large, application of high voltage to the discharge unit 4 and operation of the suction fan 55 may be started a predetermined time (e.g., several to several tens of seconds) after the ultrasonic vibrator 65 starts operating. In this case, the inside of the suction port 15 is filled with mist before application of high voltage to the discharge unit 4 and operation of the suction fan 55 start, so the degree of mixing of dust and mist can be increased and the charging efficiency (electrostatic charging efficiency) can be further improved. In addition, since mist is generated from the area facing the suction port 15, the efficiency of filling the inside of the suction port 15 with mist can be increased.

Although the electrostatic precipitator 1 according to the embodiment described above is formed in a flat rectangular parallelepiped shape, it may be in other shapes, such as a circular or polygonal shape.

Furthermore, the installation positions of the suction inlet 15 and the exhaust port 50 and the route of the air flow passage 27 are not necessarily limited to the above-described embodiment, and for example, it is possible to provide the suction inlet 15 at a position close to one side of the top plate 11 and the exhaust port 50 on the other side surface of the housing 2 to form an air flow passage for unidirectional air circulation. In that case, the repulsion portion 25 is disposed downstream of the discharge electrode 30 without being disposed so as to surround the periphery of the discharge electrode 30.
[Air purifier]

Next, an air purifying device according to an embodiment of the present invention will be described with reference to Figure 9. Here, Figure 9 is a perspective view showing an air purifying device according to an embodiment of the present invention with the front cover removed.

The air purifier 100 comprises a horizontal rectangular table 101, a rectangular parallelepiped case 102 provided below the table 101, casters 103 provided at the four corners of the underside of the case 102, and an operating unit (not shown). A rectangular top plate 104 is detachably provided in the center of the table 101, and an intake port 105 is formed in the top plate 104.

A storage space for the electrostatic precipitator 1 is provided in the upper part of the case 102, and when the electrostatic precipitator 1 is stored in the storage space, the power supply spring 43 (see FIG. 3, etc.) of the electrostatic precipitator 1 is in electrical contact with the power supply unit (not shown) of the air purifier 100. In addition, a storage space 106 for a high-voltage power supply unit, a control unit, etc. is provided to the side of the storage space in the upper part of the case 102.

The case 102 is provided with a suction fan section 107 that houses a suction fan (not shown) below the storage space for the electrostatic precipitator 1, and a deodorizing section (not shown) that houses activated carbon is provided downstream of the suction fan. An exhaust port 108 is also formed at the bottom of the case 102.

When the operation switch of the operating unit is pressed in the air purifying device 100 in which the electrostatic precipitator 1 is housed, a high voltage is applied to the electrostatic precipitator 1 via the power supply unit, and the suction fan is driven. As a result, dust-laden air containing particles such as dirty cigarette smoke from inside the room flows into the air purifying device 100 from the suction port 105, and after the particles in the dust-laden air are captured by the electrostatic precipitator 1, the clean air is returned to the room from the exhaust port 108.

The technology of the present invention can be used in electrostatic precipitators and air purifiers that collect dirty particles in the air indoors (such as cigarette smoke, pollen particles, and mist from cooking oil fumes).

REFERENCE SIGNS LIST 1 Electrostatic dust collector 2 Housing 3 Liquid tank 9 Straightening plate 15 Suction port 19 Hole 27 Air flow passage 28 Liquid 29 Liquid suction member 30 Discharge electrode 32 Wire electrode 33 Bundle portion 54 Hole 61 Mist generating portion 65 Ultrasonic vibrator 100 Air purifying device 102 Case 105 Suction port 108 Exhaust port

Claims (9)

An electric dust collector that collects dust in the air by charging it with corona discharge generated by applying a high voltage,
A liquid tank for storing a conductive liquid;
a discharge electrode disposed at a certain distance from the liquid surface of the liquid tank;
a suction port provided at a position above and facing the liquid level of the liquid tank;
a mist generating unit that mistifies the liquid in the liquid tank upward toward the suction port;
Equipped with
The air flowing in from the suction port flows toward the liquid level in the liquid tank,
the mist generating unit includes an ultrasonic vibrator, a hole is formed in a bottom surface of the liquid vat at a position corresponding to the suction port, the ultrasonic vibrator is provided at a position corresponding to the hole, and a high frequency wave is radiated upward from the bottom of the liquid vat to ultrasonically vibrate the liquid and generate a liquid column;
a plurality of the discharge electrodes are disposed around the downstream side of the suction port in the air flow direction ;
an inlet having an inclined portion that is spaced apart from the discharge electrode and inclines downward and inward from the upper portion, and a lower end portion of the inlet extends toward the liquid surface side of the liquid tank further than the lower end portion of the discharge electrode . The electrostatic precipitator according to claim 1, characterized in that the mist generating unit is equipped with a heater, and the heater is disposed in the liquid tank facing the liquid surface side of the liquid tank. The electrostatic precipitator according to claim 1 or 2, characterized in that a porous liquid-absorbing member that absorbs and holds the conductive liquid is provided in the liquid tank, the liquid-absorbing member is disposed in the liquid tank so that a liquid film is formed above the liquid-absorbing member, and an opening is provided in the area corresponding to the mist generating unit. The electrostatic precipitator according to claim 3, characterized in that the opening of the liquid suction member is formed in an area facing the suction port. The electrostatic precipitator according to claim 3 or 4, characterized in that a straightening plate with many holes is provided at the suction port, a roof is provided above the opening of the liquid suction member between the straightening plate and the liquid surface of the liquid tank, and the roof is formed in an umbrella shape that slopes downward from a position corresponding to the center of the suction port toward the liquid tank. An electrostatic precipitator according to any one of claims 1 to 5, characterized in that the discharge electrode has a bundled portion in which wire electrodes made of conductive fibers are bundled, and the tip of the discharge electrode is arranged toward the liquid surface of the liquid tank. The electrostatic precipitator according to claim 6, characterized in that the bundle of the discharge electrode is composed of 10 to 200 wire electrodes, each wire electrode having a diameter of 5 to 25 μm. An electrostatic precipitator according to any one of claims 1 to 7, characterized in that it comprises a housing having an internal space, the liquid tank is disposed within the housing, the housing is provided with a suction port at a position facing the liquid surface above the liquid tank, and an air flow passage is formed downstream of the suction port in the air flow direction so that air flowing into the housing from the suction port is diffused around the liquid tank along the liquid surface of the liquid tank. An air purifying device comprising the electric dust collector according to any one of claims 1 to 8,
An air purifying device, characterized in that the electrostatic precipitator and a suction fan are housed inside a case, an intake port in a top plate of the case is opened at the top, and an exhaust port is opened at the bottom of the case.

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