JP3503718B2 - Electrostatic precipitator and coating film for the precipitating electrode of the precipitating electrode - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an electrostatic precipitator for air cleaning.

[0002]

2. Description of the Related Art An electrostatic precipitator is widely known in which ionic wind is generated by corona discharge and floating particles are charged and separated and removed by electrostatic force.

For example, Japanese Examined Patent Publication No. 6-36875 discloses air using an electrostatic precipitator in which an ionizing wire (discharge electrode), a dust collecting electrode and a counter electrode are arranged at predetermined positions so as to achieve the above-mentioned operation. A purifier is disclosed. This technology
A DC high voltage is applied between the discharge electrode and the counter electrode and the dust collecting electrode to generate a corona discharge, which ionizes and charges the molecules and suspended particles in the air passing therethrough, and the collision energy of the ions to the molecules. Generate an ion wind to guide the charged particles into the space between the counter electrode and the dust collecting electrode, and apply a high voltage between the counter electrode and the dust collecting electrode to form a strong electric field. The charged particles are collected by the dust collecting electrode by the Coulomb force by the.

[0004]

The electrostatic precipitator having such a structure is widely used as an ion type air cleaner without a fan because air flows by the ionic wind.

However, particles of 0.1 to several microns such as air dust and cigarette smoke, which are most abundant in the living space, lose their electric charge when they are collected by the dust collecting electrode, so that the cloning force does not work and the dust collecting electrode There is a case that it is separated from and re-scatters in the air.

Therefore, an object of the present invention is to prevent re-scattering of collected particles by devising the structure of the dust collecting electrode.

Another object of the present invention is to improve the cleanability of the dust collecting electrode having a devised structure so that the dust particles accumulated there can be easily removed.

[0008]

According to the present invention, a dust collecting electrode is constructed so that an unequal electric field is formed in the vicinity of its surface, and at least a part of its surface is covered with an insulating film. It is characterized by being

As a result, not only the Coulomb force on the charged particles but also the gradient force due to the electric field gradient (electric field gradient) in the non-uniform electric field acts near the surface of the dust collecting electrode. The gradient force is a force that causes unbalanced polarization of particles due to an electric field gradient in an unequal electric field and attracts the particles in a strong electric field direction, and works even if the particles are not charged. Therefore, even if the particles collected by the dust collecting electrode lose the charge, they remain attracted to the dust collecting electrode by the gradient force.

As a concrete structure of the dust collecting electrode for forming the non-uniform electric field, a plurality of convex portions are provided on the electrode surface, a plurality of cut and raised portions and a plurality of slits are provided on the electrode, and a reticulated conductor. Is used as a dust collecting electrode, a printed circuit board having a grid printed wiring is used as a dust collecting electrode, and the like. Further, two opposite electrodes to which a voltage is applied are provided, and a fiber assembly or net of a dielectric or a conductor is arranged in an electrically floating state as a dust collecting electrode between the two electrodes. Can also be used as the dust collecting electrode. With such a configuration, the lines of electric force from the counter electrode to the dust collecting electrode are focused on the convex portions, the cut and raised portions, the slits, the grid of the net, etc. Can be done. Therefore, a gradient of electric field strength, that is, an electric field gradient is generated in the vicinity of the surface of the dust collecting electrode, and the gradient force is further applied to the charged particles attracted by the Coulomb force to the vicinity of the electrode.

The smaller the radius of curvature R of the convex portion, the better,
Further, it is desirable that the distance L between the adjacent protrusions is sufficiently narrow so that there is no gap between the protrusions where an uneven electric field is not formed. For example, the radius of curvature R is preferably 0.1 mm or less, and L / R = about 2 to 4 is preferable.
Similarly, the intervals between the cut-and-raised parts, the slits, the grid lines of the printed wiring, the grid lines of the mesh, and the fibers are also preferably sufficiently narrow so that there is no space where an uneven electric field is not formed. It is desirable that the wire diameter of the grid of the reticulated conductor or the fibers of the fiber assembly is as thin as possible, for example, 0.1 mm or less.

By the way, since the surface of the dust collecting electrode having the structure for generating the non-uniform electric field as described above is not flat, there is a problem that it is troublesome to remove the dust particles adsorbed and accumulated there. That is, the dust particles accumulated on the dust collecting electrode are generally removed by washing the electrode with water or wiping with a cloth, but unless the electrode surface is thoroughly cleaned, the particles are completely removed. Can not. Further, if the particles are reused without completely removing the particles, dust particles may be further deposited on the particles, and the distance between the particles and the counter electrode or the discharge electrode may be narrowed to cause spark discharge.

To solve this problem, the present invention covers at least a part of the surface of the dust collecting electrode with an insulating film. This insulating film may evenly cover the entire surface of the dust collecting electrode, or may fill only the convex portion, the cut-and-raised portion, or the concave portion such as the slit or mesh grid so that the surface of the dust collecting electrode becomes flat. . In any case, due to the insulation film coating,
Since the surface of the dust collecting electrode becomes flatter, that is, smoother, dust particles can be easily removed and cleaning becomes easier.

The material of this insulating film has a volume resistance of 10 ⁸ Ω.
It is preferable that m or more and the relative permittivity εc satisfy the following condition.

1 ≦ εc <εs, and εc <10 where εs is the relative permittivity of the material of the dust collecting electrode. Further, the thickness of the insulating film is preferably equal to or less than the radius of curvature of the convex portion on the electrode surface. As a result, even if the insulating film is coated, the suction holding action by the gradient force is secured.

The insulating film may be peeled off from the surface of the dust collecting electrode. By doing so, the deposited particles can be removed by peeling the insulating film from the electrode and discarding it, so that the electrode can be cleaned more easily.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The embodiments of the electrostatic precipitator of the present invention will be described in detail below with reference to the drawings.

FIG. 1 shows the principle of the dust collecting electrode of the present invention.
A convex portion 3 is provided on the surface of the dust collecting electrode 1 having a flat plate shape as a whole. The entire surface of the dust collecting electrode 1 including the convex portion 3 is covered with the insulating film 2. This dust collecting electrode 1,
When a high DC voltage V is applied between the counter electrode 5 and the counter electrode 5 which is also arranged in parallel and is opposed to this, an electric field E is generated by the lines of electric force as indicated by arrows in the figure.

Except in the vicinity of the convex portion 3, the lines of electric force flow in parallel with equal density and form a uniform electric field. The charged particles having the electric charge Q that have entered the uniform electric field receive the Coulomb force (= EQ) in the direction of the electric force line and move toward the dust collecting electrode 1.

In the vicinity of the convex portion 3, the lines of electric force are focused toward the convex portion 3 as shown by the arrow in the figure, so that in the vicinity of the convex portion,
The electric field gradient (gradient,
An unequal electric field having a strength difference). The charged particles 7 that have reached the unequal electric field due to the action of the Coulomb force are subjected to the strong Coulomb force, that is, the gradient force toward the direction of the convex portion 3.

This gradient force F (vector) is
It is generally known that it can be expressed by the following equation due to the gradient of the electric field E (vector).

[0022]

[Equation 1]

[Equation 2] Here, a is a particle diameter, εr is a relative permittivity of particles, and εm is a relative permittivity of air (medium).

The gradient force F in the vicinity of the convex portion 3 shown in FIG. 1 is calculated by the following equation.

[0024]

[Equation 3] Here, R is the radius of curvature of the convex portion, and d is the distance of the charged particles from the flat plate surface.

As can be seen from this equation, the larger the particle diameter a and the relative permittivity εr of the particles, the larger the gradient force F.

According to the calculation, when the particle diameter a becomes larger than about 0.2 μm, the gradient force suddenly becomes large. Therefore, particles having a particle diameter of 0.1 to several microns, such as air dust and cigarette smoke, which are often present in the living space, It can be expected that the gradient force will work effectively.

Further, the gradient force F increases as the radius of curvature R of the convex portion decreases, and the gradient force F decreases rapidly when the distance d from the center of the convex portion increases.

FIG. 2 is a relationship curve between the distance d from the convex portion and the gradient force F with the radius of curvature R of the convex portion as a parameter obtained from the equation (3). As environmental conditions, an electric field E = 1.0 MV / m, a particle diameter a = 1.0 μm, and a relative dielectric constant εr = 4 of the particles are selected.

From this graph, it can be seen that a large gradient force F works within the range where the distance from the surface of the convex portion of the particle corresponds to the radius of curvature R, but if the distance is farther than this, the gradient force F rapidly attenuates.

Further, even if the particles trapped on the surface of the convex portion lose the charge and become 0e, for example, when the radius of curvature R is 0.1 mm, the gradient force F on the surface of the convex portion is 1.5 × from the figure.
It is 10 ^-13 N. This is the same electric field strength E = 1.0 MV /
It is almost the same value as the Coulomb force of 1.6 × 10 ^-13 N acting on a charged particle having a charge of 1e (= 1.6 × 10 ^-19 Coulomb) in m. Experimentally, it has been found that particles having a charge of 1e are adsorbed and held by the dust collecting electrode.

Therefore, it is understood that even if the particles trapped in the convex portion having the radius of curvature R of 0.1 mm or less lose the electric charge, a sufficient gradient force works to attract and hold the particles to the dust collecting electrode. From this, if a convex part with a radius of curvature of 0.1 mm or less is provided,
It can be seen that the gradient force can be effectively used.

Further, the re-scattering phenomenon is more likely to occur as the particle diameter is larger, but as can be seen from the equation (3), the gradient force F becomes larger as the particle diameter a becomes larger, so that it acts more effectively on large particles. To do.

Next, an experiment was conducted to find out on which surface of the convex portion the gradient force works most strongly. FIG. 3 is a diagram showing the gradient force measurement position of the convex portion, and the gradient force in three directions, that is, the direction perpendicular to the electrode surface (a), the direction 45 degrees from the electrode surface (b), and the direction parallel to the electrode surface (c). F was measured. The lines of electric force are assumed to flow as shown by the arrows in the figure.

4 (a), (b) and (c) are characteristic curves of the gradient force F measured in the directions of (a), (b) and (c) of FIG. Show as.

From this figure, the gradient force F is smallest on the convex surface in the direction (a) perpendicular to the electrode surface (see FIG. 4).
(A)), it can be seen that the gradient force F in the direction (c) parallel to the electrode surface is the largest (FIG. 4 (c)). Therefore,
When a large number of convex portions are arranged on the electrode surface, it is important to arrange the convex portions at appropriate intervals so that the gradient force F in the parallel direction of each convex portion can be effectively utilized. That is, if the spacing between the convex portions is too wide, an unequal electric field is not formed between the convex portions, and there is a gap in which no gradient force is generated,
The spacing should not be too wide.

According to the experimental result shown in FIG. 4 (c), it is observed that the gradient force is rapidly attenuated when the distance from the surface of the convex portion exceeds the radius of curvature R. From this, it can be said that the range where the gradient force of each convex portion effectively works is within a distance corresponding to the radius of curvature R from the surface of the convex portion. Therefore, the distance between the centers of the protrusions is L
Then, it is desirable to select the interval of the convex portions within the range of L / R ≦ 4. On the other hand, it is necessary that L / R> 2 so that the convex parts do not mechanically overlap each other. From the above, the relationship between the radius of curvature R of the convex portion and the convex portion center interval L is L / R
= 2-4 is desirable.

It should be noted that the intervals between the convex portions do not necessarily have to be constant, and the intervals between the convex portions may vary within the range of the above conditions.

If a large number of convex portions are formed on the surface of the dust collecting electrode so as to satisfy such conditions, an unequal electric field is evenly formed on the entire surface of the dust collecting electrode, and a gradient force is generated on almost the entire surface of the dust collecting electrode. The particles collected by the dust collecting electrode can be adsorbed and held on the dust collecting electrode.

Further, not only re-scattering occurs when charged particles are collected by the dust collecting electrode and loses the electric charge, but also high resistance particles (10 ⁸ Ωm or more) such as cigarette smoke are reverse corona between the dust collecting electrode and the dust collecting electrode. Reverse ionization and re-dispersion caused by the occurrence of discharge and recharging of the particles to the anti-power generation level, and low resistance particles such as metal powder (100Ω
(m or less) is charged to the same potential as the dust collecting electrode, and the phenomenon of induced re-scattering caused by repulsive force can also be reduced by the above-mentioned gradient force.

Furthermore, the speed w at which the charged particles move to the electrode surface.
Is expressed by the following equation.

W = F / 6πaμ (4) where F is the sum of the gradient force and the Coulomb force,
a is the particle diameter, and μ is the viscosity of air.

From the equation (4), it is predicted that the moving speed w of the particles to the dust collecting electrode, that is, the dust collecting speed is increased by the large gradient force F in the vicinity of the dust collecting electrode, which prevents re-scattering from the electrode. Together with this, improvement of dust collection efficiency can be expected.

As described above, the dust collecting electrode according to the principle of the present invention favorably adsorbs and holds dust particles by the action of the gradient force of the convex portions 3 on the surface. Further, the surface of this dust collecting electrode is covered with an insulating film 2 as shown in FIG. As a result, the surface shape of the insulating film 2 becomes a smoother shape in which the unevenness of the convex portions 3 inside is moderated. As a result, as compared with the case where the electrode itself is exposed without the insulating film 2, the dust particles deposited on the electrode 1 can be removed more easily and the cleaning becomes easier. Further, the insulating film 2 includes the dust collecting electrode 1 and the particles 7
It also has the effect of preventing reverse corona discharge with and suppressing spark discharge. Therefore, it is desirable that the material of the insulating film 2 has a material having a high electric resistance, for example, a material having a volume resistance of 10 ⁸ Ωm or more.

It is desirable that the dielectric constant of the insulating film 2 be as small as possible. As the relative permittivity of the insulating film 2 increases, the polarization of the insulating film 2 becomes more prominent, so that the influence of the shape of the convex portion 3 on the electric field on the outer surface of the insulating film 2 decreases, and the electric field distribution becomes closer to even. , Because the gradient force decreases. In particular, when the relative permittivity εc of the insulating film 2 becomes larger than the relative permittivity εs of the dust collecting electrode itself, the influence of the shape of the convex portion 3 becomes ineffective. From this, the relative permittivity εc of the insulating film 2 should satisfy the condition of 1 ≦ εc <εs. Here, εs is the relative permittivity of the dust collecting electrode. Further, it is desirable from experiments that εc <10.

Preferable examples satisfying the above conditions include resin films such as polyethylene and Teflon, films of semiconductor materials such as silicon dioxide and titanium dioxide, or coating films of paints containing them as a main component.

Further, as described above, the gradient force effectively works at a distance within the radius of curvature of the convex portion, so that the thickness of the insulating film 2 is preferably within the radius of curvature of the convex portion.

FIG. 5 is a characteristic curve obtained by calculating the gradient force in the vicinity of the convex portion 3 using the thickness of the insulating film 2 as a parameter. Here, the radius of curvature of the convex portion 3 is 0.1 mm, and the material of the insulating film 2 is polyethylene (εc = 2.3).
As shown, when the film thickness is 20 μm, the gradient force on the surface of the insulating film 2 is almost the same as when the film thickness is zero. If the film thickness is made thinner than 20 μm, the gradient force will be slightly increased, but the breakdown voltage of the film will be lowered. Incidentally, polyethylene film 50 μm
In this case, the withstand voltage between the electrodes is 1 kv. Taking these into consideration, when the radius of curvature of the convex portion 3 is 0.1 mm, the film thickness is 20 μm.
It is considered appropriate to use a polyethylene film of about m.

Generally, the optimum value of the thickness of the insulating film cannot be determined unconditionally depending on the material of the insulating film, the radius of curvature of the convex portion, the distance between the electrodes, the applied voltage, etc. It is desirable to select a material whose radius is less than the radius of curvature of the convex portion, the relative dielectric constant of the insulating film material is smaller than that of the electrode material, and the relative dielectric constant is 10 or less.

With the dust collecting electrode having the above structure, it is possible to obtain the effects of preventing the particles from re-scattering, improving the cleanability, and preventing spark discharge.

Next, specific embodiments of the present invention will be described.

FIG. 6 shows the first embodiment, and the dust collecting electrode 1
1 is a conductor net, for example, a metal net 111, and an insulating film 113.
And is formed into a flat plate having a smooth surface as shown in the sectional view of FIG. Opposing flat plate electrodes 13 and 15 are arranged in parallel on both sides of the dust collecting electrode 11, and a high DC voltage V1 is applied between the dust collecting electrode 11 and the opposed flat plate electrodes 13 and 15 on both sides.

When air containing dust particles flows between the electrodes in the direction of the arrow in the figure by the action of a fan or the like (not shown), the Coulomb force of the electric field between the opposed flat plate electrodes 13 and 15 and the coated gradient dust collecting electrode 81. As a result, the charged particles are attracted toward the dust collecting electrode 81, and are suction-held on the coating surface of the dust collecting electrode 81 by the gradient force. Since the surface of the dust collecting electrode 11 is smooth, the deposited particles can be easily removed by washing the dust collecting electrode with water, vibration, or the like.

It is desirable that the grid of the metal net 111, that is, the net wire is as thin as possible, for example, the radius is 0.1 mm or less, and the pitch of the net wire is as narrow as possible, for example, 0.2 mm or less. With such a configuration, a uniform electric field is formed between the dust collecting electrode 11 and the opposing flat plate electrodes 13 and 15, but in the vicinity of the surface of the electrode 11, the lines of electric force are focused on each mesh line. Since an unequal electric field is formed, the dust particles are adsorbed and held on the metal net 11 by the action of preventing re-scattering due to the gradient force in the unequal electric field.

The insulating film 113 of the dust collecting electrode 11 is shown in FIG.
It is not always necessary to cover the entire surface of the metal net 111 as shown in FIG. 8, and the insulating film 113 may fill only the concave portions, that is, the mesh of the metal net 111, as shown in FIG. In short, it suffices for the insulating film 113 to smooth the surface of the dust collecting electrode 11 and improve the cleaning property without impairing the adsorption holding effect due to the gradient force.

FIG. 9 further shows the discharge electrode 17 in addition to the embodiment of FIG.
A modified example in which the discharge counter electrodes 18 and 19 are added is shown. The discharge electrode 17 is arranged on the upstream side of the dust collection electrode 11 in the air flow,
The discharge counter electrodes 18 and 19 are arranged so as to sandwich the discharge electrode 17. A high DC voltage V2 is applied between the discharge electrode 17 and the discharge counter electrodes 18 and 19, where corona discharge occurs.

The air flow containing dust particles coming from the direction of the arrow first passes between the discharge electrode 17 and the discharge counter electrodes 18, 19 where the dust particles are forcibly charged. Next, the air flow passes between the dust collecting electrode 11 and the opposing flat plate electrodes 13 and 15 on both sides, where the charged particles are collected by the dust collecting electrode 11. Since the dust particles are forcibly charged, a higher dust collecting effect than that of the embodiment of FIG. 6 is obtained.

FIG. 10 shows a second embodiment of the present invention. The dust collecting electrode 21 is a metal net covered with an insulating film similar to that of the embodiment of FIG. 6, and one facing plate electrode 23 is arranged on one side of the dust collecting electrode 21, and both electrodes 21,
A DC high voltage V is applied between 23. Air containing dust is caused to flow between the electrodes 21 and 23 as indicated by arrows in the figure by the action of ion wind or the like due to corona discharge at a fan (not shown) or a discharge electrode (not shown).

FIG. 11A shows the third embodiment, and 2
A high DC voltage V is applied between the opposing flat plate electrodes 31, 33. The dust collecting electrode 35 is arranged between the opposite electrodes 31 and 33 in parallel with them, without applying a voltage, that is, in an electrically floating state. The dust collecting electrode 35 is a net, fiber aggregate, paper or cloth woven with a dielectric (eg, glass fiber, resin fiber, etc.), and is covered with an insulating film having a dielectric constant lower than that of the dust collecting electrode 35 so that the surface is smooth. Has become.

Each fiber or mesh wire of the dust collecting electrode 35 causes a polarization action by the electric field between the counter electrodes 31 and 32, and therefore, FIG.
As shown in FIG. 1 (b), the lines of electric force are focused on each fiber or each net wire, and an unequal electric field is generated in the vicinity of the dust collecting electrode 35 to generate a gradient force.

Even if a metal net or a metal fiber is used instead of the dielectric net or the dielectric fiber of the dust collecting electrode 35, the metal causes a remarkable polarization because the dielectric constant can be regarded as infinite.
It has the same effect as above.

FIG. 12 shows a fourth embodiment. In the dust collecting electrode 41, the surface of a metal flat plate is roughened by sandblasting, chemical etching, plasma etching or the like, and a large number of uneven portions 33 are formed on the entire electrode surface. Is provided, and is further covered with an insulating film. When a high DC voltage V is applied between the dust collecting electrode 41 and the opposed flat plate electrode 45, an unequal electric field is formed in the vicinity of the uneven portion 33 of the dust collecting electrode 41,
Gradient force is generated, and particles in the vicinity thereof are adsorbed and held by the dust collecting electrode 41.

FIG. 13A shows a fifth embodiment, in which the dust collecting electrode 51 is pressed from the back surface of a metal flat plate to form a large number of convex portions 53 on the front surface at minute intervals, and an insulating film is formed thereon. Is coated with. When a direct current high voltage V is applied between the dust collecting electrode 51 and the opposing flat plate electrode 55, FIG.
As shown in, the electric force lines are focused on the convex portion 53, and a gradient force is generated in this portion. The insulating film 57 is the electrode 51.
Smooths the surface shape of and makes cleaning easier.

FIG. 14 (a) shows a sixth embodiment, in which the dust collecting electrode 61 is formed by cutting and raising a large number of minute intervals of a metal flat plate on the side of the counter electrode 63, and covering the surface with an insulating film. Is. When a high DC voltage V is applied between the dust collecting electrode 61 and the counter plate electrode 63, the lines of electric force are focused on the cut and raised portion 63 to generate a gradient force, as shown in FIG. 14 (b). The insulating film 67 smoothes the surface shape of the electrode 61 and facilitates cleaning.

FIG. 15A shows the seventh embodiment, and the dust collecting electrode 71 is as shown in the detailed detailed view of FIG. 15B.
A grid-shaped printed wiring 77 is formed on an insulating substrate 75, and the surface thereof is further covered with an insulating film. When a high DC voltage V is applied between the dust collecting electrode 71 and the counter plate electrode 73, the lines of electric force are focused on the edge portion of the printed wiring 77 and the gradient force is applied to the surface of the electrode 71, as shown in FIG. Occurs. The insulating film 79 smoothes the surface shape of the electrode 71 and facilitates cleaning.

FIG. 16A shows an eighth embodiment. The dust collecting electrode 81 is formed by punching a metal flat plate to provide slits 83 at minute intervals, and further covering the surface thereof with an insulating film. . When a high DC voltage V is applied between the counter flat plate electrode 85 and the flat plate electrode 85, the lines of electric force are focused on the edge portion of the slit 83 as shown in FIG. 11B, and a gradient force is generated on the surface of the electrode 81. The insulating film 87 makes the surface shape of the electrode 81 smooth and facilitates cleaning.

In some of the embodiments described above, the spacing between the grids or fibers of the metal net or the grid-like printed wiring, the spacing between the convex portions, and the width of the slits are too narrow. Therefore, the insulating film at the edge portion such as the lattice or the convex portion may become too thick. In particular, when a resist is applied to the printed wiring board 71 shown in FIG. 15 to form an insulating film, it is necessary to experimentally set the spacing of the grids of the printed wiring to the following conditions. It is desirable for forming a film. Lattice spacing ≧ 2 × (desired thickness of insulating film + thickness of printed wiring)
For example, when the desired thickness of the insulating film is 20 μm and the thickness of the printed wiring is 35 μm, the lattice spacing must be 0.11 mm or more to satisfy the above condition. In the experiment, 1 mm
The best insulating film thickness was obtained when the lattice spacing was set to some extent. As described above, in order to create a gap in which an unequal electric field does not occur, it is preferable that the lattice spacing is narrow. Therefore, this requirement is balanced with the requirement that the insulating film is not too thick, and an appropriate lattice is obtained. You should decide the interval.

Also in the embodiments shown in FIGS. 10 to 16, the insulating film does not uniformly cover the electrode surface, as shown in the embodiment of FIG. 15 in FIG. 17, as an example. Only the recesses between the fibers may be filled.

The insulating film may be detachable from the dust collecting electrode. For example, a thin insulating sheet is adhered to the surface of the dust collecting electrode in close contact, and when dust is accumulated, the insulating sheet is peeled off and discarded, and a new insulating sheet is attached to the dust collecting electrode, by using in a mode that Cleaning of the dust collecting electrode is substantially unnecessary.

Although some embodiments have been described above, the present invention is not limited to the contents of the above embodiments, and can be implemented in various modified, improved and modified forms. .

In the embodiment described above, the dust collecting electrode is set to a positive potential. Therefore, when corona discharge is generated by a discharge electrode (not shown) to charge the dust particles, a negative corona that charges the particles to a negative potential is used. Will cause a discharge,
In order to suppress the generation of ozone, a positive corona discharge may be used to bias the dust collecting electrode to a negative potential.

[0071]

As described above, according to the present invention,
It is possible to prevent re-scattering of the particles collected by the dust collecting electrode and improve the cleanability of the dust collecting electrode.

[Brief description of drawings]

FIG. 1 is a principle diagram of a dust collecting electrode of the present invention.

FIG. 2 is a characteristic curve of gradient force obtained by theoretical calculation.

FIG. 3 is a diagram showing a measurement position of a gradient force of a convex portion.

4 is a characteristic curve of gradient force at each measurement position in FIG. 3, where (a) is a direction perpendicular to the electrode surface, (b) is a direction of 45 degrees with the electrode surface, and (c) is parallel to the electrode surface. Shows the gradient force in the direction.

FIG. 5 is a characteristic curve of a gradient force in the vicinity of a convex portion with the thickness of the insulating film as a parameter.

FIG. 6 is a configuration diagram of an electrode configuration according to the first embodiment of the present invention.

FIG. 7 is a sectional view of the dust collecting electrode according to the first embodiment.

FIG. 8 is a cross-sectional view of a modification of the dust collecting electrode according to the first embodiment.

FIG. 9 is a configuration diagram of a modification of the electrode configuration of the first embodiment.

FIG. 10 is a configuration diagram of a second embodiment using a metal net dust collecting electrode.

FIG. 11A is a configuration diagram of a second W embodiment using a net-shaped dust collecting electrode arranged in parallel between opposed electrodes, and FIG.
FIG. 4 is a diagram showing focusing of lines of electric force.

FIG. 12 is a configuration diagram of a third embodiment in which a metal flat plate is blasted to use a dust collecting electrode having an uneven portion.

FIG. 13A is a configuration diagram of a fourth embodiment using a dust collecting electrode having a convex portion formed by pressing a metal flat plate;
(B) is a figure which shows the convergence of an electric force line.

14A is an electrode configuration diagram of a fifth embodiment using a dust collecting electrode obtained by cutting and raising a part of a metal flat plate, and FIG. 14B is a diagram showing focusing of lines of electric force.

FIG. 15A is a configuration diagram of a sixth embodiment using a dust collecting electrode in which a grid-like printed wiring is provided on an insulating substrate,
(B) is a detailed view of a printed wiring part, and (c) is a view showing focusing of lines of electric force.

16A is a configuration diagram of a seventh embodiment using a dust collecting electrode in which a metal flat plate is punched and slits are provided at minute intervals, and FIG. 16B is a diagram showing focusing of electric force lines.

FIG. 17 is a cross-sectional view showing a modified example of the dust collection electrode of the embodiment of FIG.

[Explanation of symbols]

1, 11, 21, 31, 41, 51, 61, 71, 81
Dust collecting electrodes 2, 113, 67, 67, 79, 87 Insulating film 3 Convex portions 5, 13, 15, 23, 33, 45, 55, 65, 7
3, 85 Opposed plate electrode 7 Charged particle V DC high voltage 43 Concavo-convex portion 53 Convex portion 63 Cut and raised portion 75 Insulating substrate 77 Printed wiring 83 Slit

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kiyoshi Fujino 2-1, 1-1 Nakajima, Kokurakita-ku, Kitakyushu City, Fukuoka Prefecture Totoki Kikai Co., Ltd. (56) Reference JP-A-4-193362 (JP, A) JP-A-53-83173 (JP, A) JP-A-62-225259 (JP, A) JP-A-3-154657 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B03C 3/00-3/88

Claims (4)

(57) [Claims] We claim: 1. forming an electric field between the dust collecting electrode and this is disposed opposite the counter electrode, in the electrostatic precipitator to dust collecting on the surface of the dust collection electrode, the counter electrode is at least Two pieces of the dust collecting electrode are provided, in which at least a part of the surface of the fiber aggregate or mesh of the dielectric or conductor is covered with an insulating film, and an unequal electric field is formed in the vicinity of this surface. And at least the above
Electrostatic precipitator, characterized in that it is arranged in an electrically floating state between even two opposing electrodes. 2. A forming an electric field between the dust collecting electrode and this is disposed opposite the counter electrode, in the electrostatic precipitator to dust collecting on the surface of the dust collection electrode, the dust collecting electrode , A metal flat plate provided with any one of a plurality of convex portions, a plurality of cut-and-raised portions, and a plurality of slits, a net-like conductor, and at least a part of a surface of a printed board having a grid-like printed wiring is insulated. Is covered with a film, an unequal electric field is formed near the surface of the film, and
An electrostatic precipitator characterized in that the surface of the insulating layer is flat. 3. A form an electric field between the dust collecting electrode and this is disposed opposite the counter electrode, in the electrostatic precipitator to dust collecting on the surface of the dust collection electrode, the dust collecting electrode , A metal flat plate provided with any one of a plurality of convex portions, a plurality of cut-and-raised portions, and a plurality of slits, a net-like conductor, and at least a part of the surface of a printed board having a grid-like printed wiring is insulated. Is covered with a film, an unequal electric field is formed near the surface of the film, and
An electrostatic precipitator, wherein a film thickness of the insulating film is equal to or less than a radius of curvature of the convex portion. 4. A coating film for a dust collecting electrode of a dust collecting electrode of an electrostatic precipitator, which can be adhered to a surface of a metal flat plate provided with a plurality of convex portions,
A coating film for a dust collecting electrode, which is made of an insulating material that can be peeled from the surface and has a film thickness that is not more than the radius of curvature of the convex portion.