JPH0685890B2 - Charge type filter - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a charge type filter, and more specifically, it forms an electric field by charging between a high voltage electrode and a ground electrode, and charges dust and a material to produce an electrostatic and / or dielectric effect. Therefore, the present invention relates to a charge-type filter which has high performance and can be used in various air cleaning fields.

[Prior Art and Problems] Conventionally, a filter that collects dust by charging it is charged by passing the dust through an electric field formed between a high voltage electrode and a ground electrode. To collect or coarsen the dust with the ground electrode and mechanically collect the dust that is not collected with the ground electrode or the dust that is collected with the ground electrode and re-scattered, for example, in Japanese Patent Laid-Open No. 56-37060. In addition to the above-mentioned system and the dust electrification part, a material made of a dielectric material is further installed between the high voltage electrode and the ground electrode to form an electric field, and the material is dielectricized to remove the dust mechanically and electrostatically. For example, the method described in JP-A-58-92471 is known. The former is generally known as an electrostatic precipitator with material, and the latter is known as a dielectric filter device.

The former method is inferior in dust collection efficiency, and
There is a drawback that it is necessary to frequently clean the ground electrode and replace the material, which is inferior in maintainability, and the latter method is superior in collection efficiency to the former,
Since the dust is highly efficiently collected, the material is significantly clogged, and the collection capacity is small and the material life is short.

Further, since all of these conventional ones use a metal wire or net as an electrode independent of the material, they are inferior in adhesion to the material and workability such as folds, and as a result, desired collection There is a drawback that the dust effect cannot be obtained, and it is necessary to remove the electrode each time to replace the material, and the workability and maintenance are inferior.

[Means for Solving the Problem] The present invention is to form a linear conductive part having a width of 5 mm or less at a non-symmetrical position on the front and back sides of a material, and to arrange the conductive part arranged on the inflow side of the airflow into a ground electrode, Do not fold the conductive part placed on the outflow side as a high-voltage electrode, and fold the material so that the linear or strip-shaped conductive part and the fold line intersect, and do not provide a dust charging part upstream of the material. The present invention relates to a charge-type filter having an integrated structure of an electrode and a non-woven fabric.

[Operations and Examples] The present invention has an extremely simple configuration in which a linear conductive portion having a width of 5 mm or less is formed at asymmetrical positions on the front and back sides of a material as a charge-type filter. The present invention will be described with reference to the drawings.
It is a top view which shows the example of the electrically conductive part of the charge type filter base material of this invention, and c) and d) are sectional drawings of a) and b), respectively.

FIG. 2 is an explanatory view showing a usage state of the charge-type filter according to the present invention.

First, the material 1 used in the present invention will be described.
As the material 1, all known air conditioning materials can be used. These materials 1 are materials made of materials such as paper, non-woven fabric, or inorganic fiber, and have a low apparent density for coarse dust to a high density called HEPA filter for ultra-high performance. Anything can be used, but since a high voltage is used in the present invention, it is necessary to use an insulating material. It is also preferable to make the material flame-retardant in case of an emergency.

In particular, a non-woven fabric containing at least 50% or more of synthetic fibers such as polyester and polypropylene serves as an induction filter at the time of charging, and is therefore considered to be the most suitable because it has a high dust collection efficiency.

Further, providing the material with a density gradient or changing the fold shape can also be effectively utilized in the present invention in the conventional manner.

Next, the conductive part 2 will be described. The conductive part 2 can be arbitrarily selected as long as it can withstand high-voltage electric charges, but a structure that does not prevent the passage of airflow is desirable. It is appropriate to use a linear body with a width of 5 mm, and when the width exceeds 5 mm, the excess area is reduced to increase pressure loss and decrease the dust holding capacity.
It is not preferable because it is also inferior in electric field formation.

Further, in the present invention, it is indispensable that the conductive part 2 is asymmetric on the front and back of the material. Therefore, in general, the specific resistance is 10 ⁴ Ω · cm.
Hereinafter, preferably 10 ⁰ Ω · cm or less of the metal wire and the conductive linear material such as carbon fiber, or silver, copper, contacting the electrically conductive powder such as aluminum or carbon resistor is 10 ⁶ Ω · cm or less It is preferable to apply the paste of (1) in a linear shape, and a double-sided body such as a breathable plate-like body such as a wire mesh or a mesh is not suitable because an asymmetric structure cannot be obtained.

The term “non-target” used in the present invention means a state in which the conductive portion on the front surface and the conductive portion on the back surface do not overlap with each other when viewed perpendicularly to the material surface.

In the present invention, the reason why the conductive parts on the front and back sides have an asymmetrical structure is essential. First, the conductive part 2 is provided on the front and back non-symmetrical parts through a material, so that the high voltage electrode 2B and the ground are connected. The distance between the electrodes and the electrode 2A can be made large, and therefore, the electric field forming region can be expanded to obtain a uniform dust collecting action and also have the action of preventing a short circuit between the electrodes. In the case of the target structure, dust is grounded to the ground electrode 2A.
If the ground electrode 2A covers the dust with the ground electrode 2A to prevent the electric field from being formed and the dust collection efficiency is reduced, the non-target structure will reduce these obstacles. To improve the dust collection efficiency and
This is because the entire material can be utilized and the dust holding capacity can be increased.

The distance between the high-voltage electrode 2B and the ground electrode 2A is 2 to 50 mm in order to prevent a short circuit and obtain a good electric field.
Is considered appropriate, and the potential difference between the electrodes is 0.2
To 1.0 kv / mm (distance between electrodes), preferably 0.5 to 0.9 kv / m
Desirably m.

Hereinafter, the reason why the airflow inflow side is the ground electrode and the outflow side is the high voltage electrode in the conductive portions formed on the front and back surfaces of the material will be described with reference to FIG. The charge-type filter shown in FIG. 2 is formed by folding a material such that the linear conductive portion and the fold line intersect each other.

The conventional charge type filter is generally provided with an ionization part for dust which is composed of a linear high voltage electrode and a plate-shaped ground electrode, and is provided with a material and a space on the inflow side of the air flow contrary to the arrangement of the present invention. The high-voltage electrode is arranged to charge the dust first, and the ground electrode is provided on the outflow side of the airflow to collect the charged dust.
Although there are drawbacks that the collection efficiency and / or the retention capacity are poor and the life is short, the present inventor has conducted diligent research to solve these problems, and as a result, the dust collection efficiency is poor. In a structure in which the ground electrode, which was not used in the past, is placed on the air flow inflow side, the dust collection efficiency is even higher than before and the dust holding capacity is much better when the material and electrode are integrated. The present invention has been completed by finding out that a charged filter having the above characteristics can be obtained.

The reason why the charge-type filter of the present invention has a much better dust holding capacity than the conventional ones, as described above,
In the charged filter of the present invention, the air flow containing dust flows from the surface of the ground electrode side to the high voltage electrode side in the material, and conversely, an electric field is formed from the high voltage electrode 2B to the ground electrode 2A. The dust that has passed through the ground electrode is charged in the material and receives an electric attraction force to the ground electrode, which is opposite to the flow of the air flow. Therefore, the dust that reaches the material is decelerated by the influence of the ventilation resistance and electric field of the material and / or the dielectric action of the material, so that it is first deposited on the surface of the material. At this time, all the dust is charged to the same polarity, so the dust does not aggregate densely and is collected as if it were raised, so even if the dust covers the surface of the material, No clogging will occur. Further, since the force of the dust to be released from the material due to the electrification is obviously smaller than the flow velocity of the air flow, the dust is not released from the surface of the material. In addition, in the present invention, since the front and back electrodes are asymmetrically installed, the direction from the high-voltage electrode to the ground electrode does not directly face the direction of the air flow but intersects obliquely, so that the distribution of the electric field is different. Since this also spreads in the horizontal direction and forms an unequal electric field that is not in a specific region as in the case where the electrodes face each other, this is also considered to be advantageous for improving the dust holding capacity.

As a result, dust is retained from the surface of the material to the inside for a while, but since all dust does not aggregate densely due to the action of the electric field, clogging is less likely to occur, and pressure loss is increased by the conventional charging method. It is much less than the expression filter.

These actions can be achieved only by providing the ground electrode on the inflow side of the air flow and the high-voltage electrode on the outflow side of the air flow.

Further, in the present invention, unlike the conventional electrostatic precipitator, since no ionization part is required, workability such as material replacement and maintenance is very excellent, and the electrostatic charge of dust is used as a dust collecting function. Instead, the mechanical collection action of the material is the main action of dust collection, and the collected dust is raised in the direction opposite to the flow of the air flow, that is, clogging by the action similar to electrostatic flocking. By reducing the dust passing speed by the electric field type and the dielectric action of the material, a charged filter having a high dust holding capacity of at least 30% or more compared with the conventional one can be obtained.

For the above reasons, the use of the electrode arrangement of the present invention makes it possible to obtain a charged filter having a much larger dust holding capacity than the conventional one.

Next, the collection efficiency will be described. Generally, the collection efficiency becomes better as the density of the filter is higher and the air velocity passing through the material is slower.

For this reason, the material adopting the configuration of the present invention can reduce the flow velocity of dust more than the flow velocity of the air flow due to the electric field formation at the same density as compared with the conventional charge filter, so that the wind velocity is substantially reduced. The same improvement in dust collection efficiency as in the case of squeezing is obtained, and if the wind speed is the same, the clogging of the material of the present invention is significantly lower than that of the conventional one, which causes an increase in pressure loss. Instead, it is possible to use a higher density material, so that in any case, the collection efficiency can be improved.

Further, an advantage of arranging the ground electrode on the air flow inflow side is that excessive accumulation of charged dust particles may cause dust release due to a repulsive action between dust particles and a reduction in collection efficiency. Since the present invention is always grounded by the ground electrode, these obstacles due to charge accumulation do not occur.

Hereinafter, the charge type filter of the present invention will be described more specifically by way of examples, but the present invention is not limited to these examples.

[Example 1] As a material, a basis weight of 100% of flame-retardant polyester fiber (1.5 denier, 44 mm long and 3 denier, 51 mm long) 150 g / m
^2, using a combined web having a thickness of 3mm with an adhesive of a polyvinyl chloride-based nonwoven, adhesive in parallel lines of the line spacing 12mm multifilament carbon fibers having a specific resistance 1.8Ω · cm to this surface Then, as shown in FIG. 1 a), the same carbon fiber multifilament is installed on the back surface of the material at a position not symmetrical to the front surface at the same interval as the front surface to form a conductive part. A charged filter substrate was obtained.

This base material is folded and the average potential difference between the electrodes is 0.8 kv / mm.
Was charged under the conditions described above and tested according to the test method of JIS D-1612, and when the pressure loss reached 100 mmAq, the dust retention capacity and the dust collection efficiency were measured.

As is clear from Table 1, the charge-type filter of the present invention is far superior in dust holding capacity and collection efficiency to those of the comparative example, and has an extremely good dust collecting action. It was the most suitable as an air cleaner for internal combustion engines.

[Comparative Example 1] For comparison with Example 1, the same non-woven fabric as in Example 1 was used as a material, and a wire mesh was used as a high voltage electrode and a ground electrode instead of the conductive portion made of carbon fiber according to the material shape. Then, a test piece was prepared, superposed on the overlayer, and tested under the same conditions as in Example 1.

The results are shown in Table 1. The dust retention capacity and the collection efficiency are inferior to those of the examples, and the clogging is apt to occur, and the life is extremely short.

[Example 2] As a material, the average fiber diameter was 2μ, the basis weight was 60 g / m ² , and the thickness was 0.
Using a 5mm polyolefin meltblown non-woven fabric laminated with a dry process non-woven fabric with an average denier of 2 denier made of polyclar fiber and modacrylic fiber having a basis weight of 120g / m ² and 1.1mm thickness The specific resistance after drying and solidification is 10 ² Ω · cm at the non-target position.
The conductive coating material was applied in parallel lines having a width of 2 mm and a line interval of 16 mm to form conductive parts, and a charge-type filter according to the present invention was obtained.

This product is also fold-processed and the ASHR-AE 52-7
The colorimetric test was conducted according to 6 and the results are shown in Table 2. It shows excellent collection efficiency even for extremely fine dust and has a low pressure loss, It was useful as a performance filter.

[Comparative Example 2] The same material as that used in Example 2 was made into an electret by previously charging it with a high voltage, and then this was folded to compare it with that of Example 2 as an electret filter. I went.

The results are also shown in Table 2, and compared with those in Example 2,
The dust collection efficiency was the same, but the storage capacity was much worse.

[Advantages of the Invention] The charge filter according to the present invention does not require any special material, equipment, or the like, since the materials that have been conventionally used can be used as they are. In addition, a conductive linear body such as a metal wire or a conductive powder such as silver or carbon, which becomes a conductive portion formed at asymmetrical positions on the front and back of the material, which is an essential component of the present invention, is used as an adhesive or the like. The dispersed paste can be obtained at low cost and easily, and there is no difficulty in the laminating work.

And, as described above, the charge-type filter of the present invention is much superior in dust holding capacity to the conventional one.
This not only reduces the number of times that the charge-type filter needs to be replaced, but also enables extremely long-term use by performing dust removal work of a conventional level. Therefore, the maintenance and cost associated with the replacement of the charge type filter are reduced, and the cost is very excellent.

Moreover, since the dust is collected in the raised state, the increase in pressure loss is much lower than the conventional one, and as a result,
When used as an air cleaner for an internal combustion engine, etc., intake efficiency or combustion efficiency is improved, which contributes to improved fuel efficiency and output. In the general air cleaning field, it is possible to process higher density materials and a larger amount of airflow. Is possible,
It is possible to provide an air purifier having a high performance and a compact structure.

Therefore, the charge-type filter of the present invention not only has a good dust collection efficiency, which is its original function, but also has a high dust holding capacity and a long service life, and is excellent in economic efficiency and productivity.
It is an ideal charge filter with a wide range of applications.

[Brief description of drawings]

1 (a) and 1 (b) are plan views showing examples of the conductive parts of the charge-type filter substrate of the present invention, and c) and d) are cross-sectional views of a) and b), respectively. FIG. 2 is an explanatory view showing a usage state of the charge-type filter according to the present invention. The numbers in the figure are 1 ... material, 2 ... conductive part 2A ... ground electrode, 2B ... high voltage electrode

Claims (3)

[Claims] 1. A linear or strip-shaped conductive portion is formed at a non-symmetrical position on the front and back of the material, the conductive portion arranged on the inflow side of the air flow is a ground electrode, and the conductive portion arranged on the outflow side is a high-voltage electrode, In addition, the material and the non-woven fabric are integrally structured so that a linear or strip-shaped conductive portion and a fold line intersect each other and a dust charging portion is not provided upstream of the material. Expression filter. 2. The charge-type filter according to claim 1, which has a structure in which the conductive portion is formed by adhering a conductive linear body having a specific resistance of 10 ⁴ Ω · cm or less to the material surface. 3. The charge-type filter according to claim 1, wherein the conductive portion is formed by applying a conductive paste having a specific resistance of 10 ⁶ Ω · cm or less.