JP2005032710A - Discharge device and air cleaning device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make a discharge device performing streamer discharge applicable for an air cleaning device for home use, and improve performance thereof by reducing noise of the discharge device. <P>SOLUTION: A frequency of sound at the streamer discharge is made 6kHz or higher by setting a distance between a discharge electrode (13) and an opposing electrode (14) at 10 mm or less, and performing the streamer discharge between the electrodes (13, 14), by the above, the sound is made to exceed an area in which a human acoustic sense becomes sensitive. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a discharge device and an air purification device that perform streamer discharge, and particularly relates to a technique for reducing streamer discharge noise.

  2. Description of the Related Art Conventionally, an air purification apparatus provided with a discharge device has been used as means for decomposing and removing odor components and harmful components by plasma generated by discharge. Among these discharge methods, the streamer discharge method is suitable for decomposing and deodorizing harmful components because high decomposition efficiency can be obtained with relatively low power.

FIG. 8 schematically shows the configuration of the discharge device in the air purification device. In this discharge device (29), as a discharge electrode for generating low-temperature plasma, a projection-like discharge electrode (30), and a flat plate-like counter electrode (31) facing the tip of the discharge electrode (30) And are used. Then, a discharge is performed between the electrodes (30, 31) to generate a low temperature plasma, and activated species (fast electrons, ions, radicals, other excited molecules, etc.) generated by the low temperature plasma are contained in the gas to be processed. By bringing harmful components and odor components into contact with ventilation, these components are decomposed and removed (see, for example, Patent Document 1).
JP 2002-336689 A

  However, the streamer discharge method produces a relatively loud discharge sound due to air breakdown. In addition, since the frequency of the discharge sound is in a range that can be felt very sensitively to human hearing, the discharge sound may become noise during operation of an air purifier using a streamer discharge method. Therefore, this streamer discharge method is considered unsuitable for places where a certain level of silence is desired, such as living spaces and small stores. On the contrary, if it becomes possible to reduce the discharge sound of the streamer discharge, the streamer discharge can be applied to a small-sized air purification apparatus for consumer use and the high decomposition efficiency can be utilized in a wide range of fields.

  The present invention has been made in view of such a point, and an object of the present invention is to reduce noise of a discharge device that performs streamer discharge, and thus to be applicable to an air purification device for consumer use. It is to improve the performance.

  The present invention reduces the noise during streamer discharge by increasing the frequency of the sound during streamer discharge and making it higher than the region where human hearing is sensitive.

  Specifically, in the first invention, a discharge electrode (13), a counter electrode (14) facing the discharge electrode (13), and a connection for applying a discharge voltage to both the electrodes (13, 14) are provided. And a power supply means (18), and a discharge device that performs streamer discharge between the electrodes (13, 14).

  The discharge device is characterized in that the electrodes (13, 14) are configured such that the frequency of the streamer discharge sound is 6 kHz or more.

  The “sound frequency” means the center frequency of the discharge sound that is generated because the current flows in a pulsed manner during the streamer discharge. The center frequency is a frequency at which the sound pressure level becomes maximum when the sound pressure level is measured for each frequency, whereas the discharge sound that is actually generated varies in frequency.

  Here, the relationship between human auditory sensitivity and frequency will be described in detail.

  The sensitivity of human hearing to noise and the like varies depending on the frequency of the sound. Therefore, when measuring the loudness with a sound level meter or the like, it is common to perform appropriate numerical correction for each frequency so that it is closer to the human sense. For example, as described in the noise measurement method of JIS C 1502 “Normal Sound Level Meter”, the overall noise level is brought close to human hearing by adding and subtracting a correction coefficient called A characteristic for each frequency. Can do.

  According to the A characteristic, when the frequency is in the range of about 1 kHz or more and less than 6 kHz, the correction coefficient is a positive value, which means that human hearing senses sound in this range relatively strongly. On the other hand, when the frequency is 6 kHz or more, the correction coefficient is a negative value, which means that human hearing feels the sound in this range relatively weak. As described above, the frequency of the generated noise greatly affects the noise level captured by humans. If the main frequency (center frequency) of the generated frequency can be set to 6 kHz or more, the noise actually felt by humans Can be effectively reduced.

  In the first aspect of the invention, since both the electrodes (13, 14) are configured so that the streamer discharge sound frequency (center frequency) is 6 kHz or more, the discharge sound frequency is 1 kHz which is sensitive to human hearing. As mentioned above, it exceeds the area below 6 kHz. Therefore, noise during streamer discharge can be reduced.

  According to a second aspect of the present invention, there is provided a discharge electrode (13), a counter electrode (14) facing the discharge electrode (13), and a power supply means connected so as to apply a discharge voltage to both the electrodes (13, 14). (18) and a discharge device that performs streamer discharge between the electrodes (13, 14). The discharge device is characterized in that the electrodes (13, 14) are configured so that the remaining time of the charged particles (22) generated by the streamer discharge is 0.17 ms or less. It is.

  Here, the mechanism of the streamer discharge and the remaining time of the charged particles (22) will be described together.

  (A), (B), and (C) of FIG. 4 show the concept of movement of electrons (21) and charged particles (22) (plus ions) in a streamer discharge step by step.

  During the streamer discharge, a micro arc called a leader (23) is generated from the discharge electrode (13) toward the counter electrode (14). At the tip of the reader (23), air is ionized into electrons (21) and charged particles (22) by a strong potential gradient. When the charged particles (22) reach the counter electrode (14) side, one discharge is completed.

  At this time, electrons (21) generated by ionization move toward the discharge electrode (13), and the charged particles (22) move to the counter electrode (14) (FIG. 4A). Here, since the charged particles (22) generated by ionization have a relatively large mass compared to the electrons (21), the moving speed is higher for the charged particles (22) than for the electrons (21). Becomes slower. Therefore, charged particles (22) remain temporarily between the electrodes (13, 14) during one discharge (FIG. 4B). At this time, the time during which the charged particles (22) remain between the two electrodes (13, 14) by one discharge is defined as the remaining time. When the remaining charged particles (22) completely move to the counter electrode (14), the electric field returns to the original electric field between the electrodes (13, 14), and discharge starts again (FIG. 4C). ). As described above, during the streamer discharge, the cycle of (A) → (B) → (C) is repeated. Due to the intermittent movement of the charged particles (22) generated in this cycle, the current is generated in the streamer discharge. It is flowing in pulses.

  In the second aspect of the invention, the electrodes (13, 14) are configured so that the remaining time of the charged particles (22) generated by the streamer discharge is 0.17 ms or less. With this configuration, the above-described cycle (A) → (B) → (C) at the time of the streamer discharge is performed earlier, and the frequency of the sound due to the pulsed current flowing at the time of the streamer discharge is 6 kHz or more. . Therefore, the frequency of the discharge sound generated at the time of the streamer discharge exceeds 1 kHz or more and less than 6 kHz that is also sensitive to human hearing. For this reason, the discharge sound at the time of streamer discharge can be reduced.

  According to a third aspect of the present invention, there is provided a discharge electrode (13), a counter electrode (14) facing the discharge electrode (13), and a power supply means connected so as to apply a discharge voltage to both the electrodes (13, 14). (18) is assumed.

  The discharge device is characterized in that a distance (L) between the discharge electrode (13) and the counter electrode (14) is 10 mm or less.

  Here, in the conventional streamer discharge, a distance longer than 10 mm is provided between both electrodes. However, as the distance between the two electrodes increases, the distance until the charged particles (22) reach the counter electrode increases, and as a result, the remaining time of the charged particles (22) also increases. For this reason, since the frequency of the sound at the time of the streamer discharge is lowered, the frequency of this sound tends to be in the range of 1 kHz or more and less than 6 kHz that acts sensitively to human hearing.

  In the third aspect of the invention, since the distance (L) between the discharge electrode (13) and the counter electrode (14) is 10 mm or less, which is shorter than before, the charged particles (22) generated by the streamer discharge are reduced. The distance traveled to the counter electrode (14) is shortened. Therefore, the remaining time in which the charged particles (22) remain between the electrodes (13, 14) is shortened, and the frequency of sound is increased. Therefore, the sound frequency (center frequency) during the streamer discharge is higher than the range in which human hearing is sensitive, and the discharge sound is reduced.

  According to a fourth invention, in the discharge device of the first, second or third invention, the discharge electrode (13) has a plurality of protruding discharge ends (17), and the counter electrode (14) It is formed in a plate shape, and the tip of the discharge end (17) of the discharge electrode (13) and the electrode surface of the counter electrode (14) are arranged to face each other.

  Here, the `` plate shape '' indicating the shape of the counter electrode (14) means a flat shape with a small thickness.For example, the counter electrode (14) is a flat plate, A punching plate with holes may be used, or a wire mesh (mesh) shape may be used.

  In the fourth aspect of the invention, a plurality of protruding discharge ends (17) are arranged on the discharge electrode (13), and the counter electrode (14) facing the discharge end (17) is plate-shaped. In this configuration, streamer discharge is performed between the discharge end (17) and the counter electrode (14).

  As described above, streamer discharge is performed by movement of electrons (21) and charged particles (22) between the discharge electrode (13) and the counter electrode (14). At this time, the leader (23) (micro arc) continuously advances from the discharge electrode (13) toward the counter electrode (14). In this micro arc generation region (discharge region), active species (fast electrons, ions, radicals, other excited molecules, etc.) for decomposing the target gas are generated.

  At this time, the electrode surface of the discharge end (17) has a relatively small area with respect to the electrode surface of the counter electrode (14). ) And spreads in the form of a flare. For this reason, the discharge region is widened, and active species for decomposing the target gas are generated over a wide range.

  In addition, since a plurality of discharge ends (17) are arranged on the discharge electrode (13), micro arcs advance in a flare form from the plurality of discharge ends (17), respectively. Therefore, the discharge region generated between the discharge electrode (13) and the counter electrode (14) becomes wider and more active species are generated.

  According to a fifth invention, in the discharge device of the fourth invention, the discharge end (17) of the discharge electrode (13) is formed in a flat plate shape.

  In the fifth aspect of the invention, the discharge end (17) is made flat and thin, thereby narrowing the discharge surface of the discharge end (17). Thus, when the discharge surface becomes narrow, the inequality of the electric field in the discharge region increases.

  By the way, if the distance (L) between the discharge electrode (13) and the counter electrode (14) is shortened, sparks are likely to occur. There is sex. On the other hand, in the invention described in claim 5, since the electric field inequality in the discharge region can be increased by narrowing the discharge surface of the discharge electrode (13), The distance (L) between the electrodes (13, 14) can be shortened. Therefore, the time for the charged particles (22) to reach the counter electrode (14) can be further shortened, and the frequency of the streamer discharge sound can be increased. Therefore, the discharge noise can be further reduced.

  Further, the electric field intensity in the discharge region can be increased by narrowing the discharge surface of the discharge electrode (13) and narrowing the distance (L) between the electrodes (13, 14). Here, since the moving speed of the charged particles (22) is proportional to the electric field strength, when the electric field strength increases, the speed at which the charged particles (22) move to the counter electrode (14) also increases. Therefore, the remaining time in which the charged particles (22) remain between the electrodes (13, 14) is shortened. Therefore, since the frequency of the streamer discharge sound is further increased, the noise during the streamer discharge can be further reduced.

  According to a sixth invention, in the discharge device of the first, second or third invention, the discharge electrode (13) is formed in a linear shape or a rod shape, and is disposed substantially parallel to the counter electrode (14). It is characterized by this. Here, “linear or rod-like” representing the shape of the discharge electrode (13) means an elongated shape with a substantially constant cross-sectional area. In addition, “the discharge electrode (13) is disposed substantially parallel to the counter electrode (14)” specifically means that the discharge electrode (13) is disposed parallel to the electrode surface of the counter electrode (14). However, the electrode surface of the counter electrode (14) may be flat or curved, or may be an elongated line or rod.

  In the sixth aspect of the invention, streamer discharge is generated from the tip of the discharge electrode (13) disposed substantially parallel to the counter electrode (14) toward the electrode surface of the counter electrode (14). In this case, even if the tip of the discharge electrode (13) is worn out due to fast electrons or active species generated during discharge, the discharge electrode (13) is disposed substantially in parallel with the counter electrode (14). The distance between the discharge electrode (13) and the counter electrode (14) is kept constant.

  Further, the discharge electrode (13) is linear or rod-shaped, and the tip shape does not change even when worn. Therefore, even when the discharge electrode (13) is worn out, the discharge characteristics are maintained, and streamer discharge is stably generated.

  7th invention presupposes the to-be-processed gas between both electrodes (13,14), and presupposes the air purification apparatus which processes to-be-processed gas with a discharge device, The said discharge device is 1st to 6th. It is a discharge device according to any one of the inventions.

  In the seventh aspect of the invention, since the air purifier is provided with the discharge device having the effects of the first to sixth aspects of the invention, the noise during streamer discharge is reduced and the air purifier has high decomposition performance. Can be provided.

  In the present invention, the following effects are exhibited.

  According to the first aspect of the invention, the discharge electrode (13) and the counter electrode (14) are configured so that the frequency of sound during streamer discharge is 6 kHz or more. Thereby, the frequency of the discharge sound exceeds the range of 1 kHz or more and less than 6 kHz that is sensitive to human hearing, and the discharge sound can be effectively reduced. Therefore, since noise during streamer discharge is reduced, the discharge device (11) can be applied to a wider range of air purification devices such as consumer use.

  According to the second aspect of the invention, the electrodes (13, 14) are configured such that the remaining time of the charged particles (22) is 0.17 ms or less during streamer discharge. As a result, the movement of the charged particles (22) between the electrodes (13, 14) is performed quickly, so that the frequency of sound during streamer discharge is increased. As a result, the frequency of the sound becomes 6 kHz or more and exceeds the range sensitive to human hearing, so that noise during streamer discharge can be reduced.

  According to the third aspect of the invention, both electrodes (13, 14) are arranged such that the distance (L) between the discharge electrode (13) and the counter electrode (14) is 10 mm or less. As a result, the moving distance of the charged particles (22) during streamer discharge is shortened, and the charged particles (22) quickly move to the counter electrode (14). For this reason, since the frequency of the sound is increased, it is possible to effectively reduce the discharge sound.

  Further, when the distance (L) between the electrodes (13, 14) is shortened, the voltage required for the streamer discharge is lowered. On the other hand, when the voltage required for the discharge is high, for example, from the viewpoint of insulation design, it is necessary to ensure a sufficient spatial distance and creepage distance between the discharge electrode (13) and the casing. On the other hand, if the voltage required for the streamer discharge is lowered, the necessary insulation distance can be reduced. Therefore, the air purification device equipped with the discharge device (11) can be made compact.

  According to the fourth aspect of the invention, the discharge electrode (13) is formed as a protruding discharge end (17) and the counter electrode (14) is formed as a plate to perform streamer discharge. Thereby, the micro arc generated from the discharge end (17) advances in a flare shape. Therefore, the discharge region is widened, and active species for decomposing the target gas are generated in a wider range. For this reason, the decomposition | disassembly efficiency of the object gas by streamer discharge can be improved.

  Further, since the discharge electrode (13) is provided with a plurality of discharge ends (17), the micro arcs are respectively flared from the plurality of discharge ends (17). The discharge region between both electrodes (13, 14) becomes wider and more active species are generated. Thereby, the decomposition efficiency of the target gas can be further improved.

  According to the fifth aspect, since the shape of the discharge end (17) of the discharge electrode (13) is a flat plate, the discharge surface of the discharge electrode is narrowed, and the electric field inequality in the discharge region is increased. Therefore, the distance (L) between the electrodes (13, 14) can be shortened without generating a spark. Furthermore, since the electric field strength can be increased by shortening the distance (L), the moving speed of the charged particles (22) can be further increased. For this reason, the frequency of the sound generated by the streamer discharge is increased, and the discharge sound can be further reduced.

  Further, when the electric field strength between the electrodes (13, 14) is increased, streamer discharge is more stably performed, and thus more stable decomposition efficiency can be obtained for the target gas.

  According to the sixth aspect of the invention, the rod-like or linear discharge electrode (13) and the counter electrode (14) are arranged substantially in parallel. Therefore, even if the tip of the discharge electrode (13) is worn by active species or fast electrons, the distance between the electrodes (13, 14) can be kept constant. Therefore, the distance between the electrodes (13, 14) can be maintained at an optimum interval, and the noise reduction effect as described above can be stably obtained. Further, by maintaining the distance between the electrodes (13, 14) at an optimum distance, the stability of the streamer discharge in the discharge device (11) can be improved.

  Furthermore, in the present invention, even if the tip of the discharge electrode (13) is worn, the tip shape of the discharge electrode (13) is not changed, so that the original discharge characteristics can be continuously maintained. The streamer discharge can be further stabilized. Therefore, it is possible to prevent the occurrence of sparks and abnormal discharge due to the change in the tip shape of the discharge electrode (13).

  According to the seventh aspect of the invention, since the air purification apparatus includes the discharge device having the effects of any one of the first to sixth aspects, the discharge noise is reduced and the air with high decomposition efficiency is provided. A purification device can be provided. Therefore, the air purification device can be applied as a consumer application that is particularly desired to be used with low noise.

Embodiment 1 of the Invention
Hereinafter, Embodiment 1 of the present invention will be described in detail based on the drawings.

  FIG. 1 is an exploded perspective view of an air purification device (1) according to Embodiment 1 of the present invention. This air purification device (1) is a consumer-use air purification device used in ordinary homes and small stores.

  The air purification device (1) includes a box-shaped casing body (2) having one end opened, and a front cover (3) fitted to the opening. Air suction ports (4) for introducing a gas to be processed are formed at both ends of the front cover (3). Further, an air discharge port (5) through which the gas to be processed flows out is formed on the upper surface of the casing body (2). Further, in the casing body (2), a fan (not shown) for circulating the gas to be processed, a flow path (6) of the gas to be processed, and a functional component (7) provided for air cleaning, Is arranged.

  The functional component (7) includes a prefilter (8), an ionization unit (9), a dust collection filter (10), a discharge device (11), and a catalyst unit (12).

  The prefilter (8) is for collecting relatively large dust contained in the air as a pretreatment of the gas to be treated. The next ionization unit (9) is for charging relatively small dust, and the charged dust is collected by a dust collection filter (10) (electrostatic filter). Further, a discharge device (11) and a catalyst unit (12) for performing streamer discharge are arranged at the subsequent stage of the dust collection filter (10). The catalyst portion (12) has, for example, a honeycomb structure, and has a catalytic action for enhancing the activity of low-temperature plasma generated by the discharge of the discharge device (11) and promoting the reaction.

  Next, the discharge device (11) will be described in detail.

  FIG. 2 (A) is an enlarged view of a main part showing the electrode structure of the discharge device (11), and FIG. 2 (B) is a front view of the main part of the discharge electrode (13).

  The discharge device (11) includes a discharge electrode (13), a counter electrode (14) facing the discharge electrode (13), and an electrode frame (15) for supporting the electrodes (13, 14). It is configured. Both electrodes (13, 14) are positioned within the frame of the electrode frame (15), and the discharge electrode (13) and the counter electrode (14) are alternately arranged in parallel so as to be at a constant interval. ing.

  As shown in FIGS. 2A and 2B, the discharge electrode 13 includes a plate-like discharge substrate 16 supported by the electrode frame 15 and a protrusion-like discharge end 17. ). The discharge ends (17) are flat and triangular, and a plurality of discharge ends (17) are provided at predetermined intervals on the discharge substrate (16). The plate thickness (d) of the flat plate at the discharge end (17) is preferably about 0.1 mm. Further, as shown in FIG. 2 (C), a plurality of discharge terminals (17) provided on the discharge substrate (16) are bent horizontally at a predetermined angle with respect to the discharge substrate (16). May be.

  On the other hand, the counter electrode (14) facing the discharge electrode (13) has a plate shape, and the electrode surface of the counter electrode (14) is substantially orthogonal to the tip of the discharge end (17). It is attached to the frame (15). At this time, the distance (L) from the tip of the discharge end (17) of the discharge electrode (13) to the electrode surface of the counter electrode (14) is preferably 10 mm or less, and more optimal distance (L) Is 3 mm or more and 10 mm or less. In the discharge device (11) in the present embodiment, the distance (L) is 5 mm.

  Further, in the present embodiment, the discharge substrate (16) of the discharge electrode (13) is provided with the discharge ends (17) on both the left and right sides in FIG. Correspondingly, the counter electrode (14) also has electrode surfaces on both sides. In this structure, the electrodes (13, 14) alternately arranged in the electrode frame (15) perform streamer discharge on both the left and right sides of the discharge electrode (13).

  Further, the discharge device (11) includes power supply means (18) for applying a discharge voltage to the discharge electrode (13) and the counter electrode (14). In this embodiment, a DC voltage is applied as the discharge voltage of the power source means (18). At this time, a method of controlling the discharge current value to be constant is preferable.

-Driving action-
Next, the operation of the air purification device (1) will be described.

  When the air purification device (1) is energized, a fan (not shown) is activated, and the gas to be treated is sucked from the air suction port (4) of the front cover (3) and introduced into the distribution path (6). In the first stage, relatively large dust in the gas to be treated is collected and removed by the prefilter (8). Furthermore, in the second stage, relatively small dust in the gas to be treated is charged by the ionization section (9) and flows downstream, and these charged dust is collected and removed by the dust collection filter (10). Is done. As described above, the dust in the gas to be treated is generally collected and removed by the two-stage physical treatment.

  Next, the gas to be processed that has been subjected to the above-described two-stage treatment is introduced into the discharge device (11) as a third stage. Low temperature plasma is generated by streamer discharge between the discharge electrode (13) and the counter electrode (14) of the discharge device (11), and the gas to be processed passes through this low temperature plasma generation region. At this time, highly reactive active species (fast electrons, ions, radicals, other excited molecules, etc.) are generated between the electrodes (13, 14) due to the low-temperature plasma, and the gas to be treated The harmful substances and odor components therein are decomposed and removed by aeration contact with the active species. Further, a catalyst part (12) is disposed in the vicinity of the discharge device (11), and decomposition of the gas to be treated can be promoted by the catalytic action of the catalyst part (12). With such a configuration, harmful substances and odor components in the gas to be treated are decomposed and removed with high efficiency by a synergistic effect of low temperature plasma and catalytic action.

  The gas to be treated purified by the above processing is discharged upward from the air discharge port (5) of the casing body (2).

  Next, a description will be given of the result of verification by experiment on the effect of reducing the streamer discharge sound in the present embodiment.

  FIG. 3 shows the relationship between the distance (L) between the discharge electrode (13) and the counter electrode (14) during streamer discharge and the frequency of the sound generated at this time. In this experiment, streamer discharge was performed in a discharge device (11) having a discharge electrode (13) having a protruding discharge end (17) and a plate-like counter electrode (14). At this time, the frequency of sound generated by the streamer discharge is measured in detail while changing the distance (L) between the electrodes (13, 14). Note that the sound frequency shown in FIG. 3 is obtained by measuring the center frequency of the discharge sound emitted from the streamer discharge. Here, the center frequency means a frequency at which the level becomes maximum when the sound pressure level is measured for each frequency.

  In FIG. 3, the solid line (e) shows the relationship between the distance (L) and the sound frequency when the current value (current density) per discharge electrode (13) is 20 μA. The broken line (f) corresponds to the distance (L) between the electrodes (13, 14), and the distance (L) and the sound when the current flows at the minimum current density that allows streamer discharge. This shows the relationship with frequency. Therefore, a predetermined streamer discharge is possible in the region above the broken line (f), and a streamer discharge is not possible below the broken line (f).

  As shown in FIG. 3, when the distance (L) between the discharge electrode (13) and the counter electrode (14) is shortened, the frequency of sound during streamer discharge is increased. This means that by shortening the distance (L) between the electrodes (13, 14), the time for the charged particles (22) generated during the streamer discharge to reach the counter electrode (14) is shortened, and the charged particles This is due to the decrease in the remaining time of (22).

  According to FIG. 3, when the distance (L) between the electrodes (13, 14) during streamer discharge is 10 mm, the sound frequency exceeds 6 kHz in both the solid line (e) and the broken line (f). . In the broken line (f), when the distance (L) is 9 mm, streamer discharge is possible at a current density of about 10 μA or more, and the frequency of the sound at this time is increased to about 6.5 kHz. Further, when the distance (L) is set to 5 mm as in the present embodiment, streamer discharge is possible at a current density of about 3 μA or more, and the frequency of the sound at this time is further increased to about 8 kHz. I understand that. If the sound frequency is 6 KHz or higher in this way, the discharge sound can be made difficult to hear for human hearing. However, the substantial upper limit of the sound frequency is realistic for human hearing. It is 20 KHz, preferably 30 KHz, which is almost impossible to capture.

-Effect of Embodiment 1-
In the first embodiment, if the distance (L) between the electrodes (13, 14) during streamer discharge is 10 mm or less, the frequency of the streamer discharge sound is 6 kHz or more. On the other hand, the remaining time of the charged particles (22) between the electrodes (13, 14) means, in other words, the reciprocal of the sound frequency. When the sound frequency is 6 kHz or more, the remaining time is 0.17 ms. It becomes as follows.

  Thus, in this embodiment, since both electrodes (13, 14) of the discharge device (11) are configured such that the frequency of the streamer discharge sound is 6 kHz or more, the frequency of the discharge sound is human. The frequency range that is sensitive to hearing is exceeded. Accordingly, it is possible to sufficiently reduce the noise during streamer discharge.

  In the present embodiment, the discharge electrode (13) is provided with a plurality of protruding discharge ends (17), and streamer discharge is performed between the plate-like counter electrode (14). With this structure, the discharge region is widened and active species are generated in a wide range, so that the decomposition efficiency of the target gas can be increased.

  Furthermore, since the discharge end (17) is a flat plate and the plate thickness (d) is as thin as 0.1 mm, the inequality of the electric field in the discharge region generated from the discharge end (17) is increased, Sparks are less likely to occur. Therefore, the distance (L) between the electrodes (13, 14) can be further shortened. Further, since the electric field strength can be increased by shortening the distance (L), the moving speed of the charged particles (22) is increased, and the remaining time of the charged particles (22) is shortened. Therefore, the frequency of the sound during discharge can be further increased, and the noise during streamer discharge can be further reduced.

  In the first embodiment, a DC voltage is applied as the discharge voltage of the power source means (18) of the discharge device (11). Thereby, the cost concerning the operation of the discharge device (11) can be reduced. At this time, if the discharge current value of the discharge voltage is controlled to be constant, the frequency of the sound during the streamer discharge can be stabilized, and spark due to abnormal discharge can be easily prevented. For this reason, the discharge noise can be reduced.

<< Embodiment 2 of the Invention >>
Next, a second embodiment of the present invention will be described in detail based on the drawings.

  FIG. 5 is an exploded perspective view of the air purification device (1) according to the second embodiment, and FIG. 6 is a view of the inside of the air purification device (1) as viewed from above. This air purification device (1) is a consumer air purification device used in general households, small stores, etc., like the air purification device of the first embodiment.

  The air purification device (1) includes a box-shaped casing body (2) having one end opened, and a front cover (3) attached to the open end surface of the casing body (2). Air inlets (4) through which room air, which is a gas to be treated, is introduced are formed on both side surfaces and the front center of the front cover (3). Further, an air discharge port (5) through which room air flows out is formed near the back side of the top plate of the casing body (2).

  A circulation passage (6) through which room air flows is formed in the casing body (2) from the air suction port (4) to the air discharge port (5). In this distribution passage (6), various functional parts (7) for purifying air and the indoor air are circulated through the distribution passage (6) in order from the upstream side (lower side in FIG. 6) of the flow of indoor air. A centrifugal blower (40) is provided for the purpose.

  The functional component (7) includes a pre-filter (8), an ionization section (9), a discharge device (11), a dust collection filter (10), and a catalyst filter (12) in this order from the front cover (3) side. Has been configured. Further, near the rear lower side of the casing body (2) of the air purification device (1), a power supply means (18) of the discharge device (11) is provided.

  The pre-filter (8) is a filter that collects relatively large dust contained in room air. The ionization unit (9) charges relatively small dust that has passed through the pre-filter (8), and the dust is collected on the downstream side of the ionization unit (9) (electrostatic filter) (electrostatic filter) ( It is for collecting by 10). The ionization section (9) is composed of a plurality of ionization lines (9a) and a counter electrode (9b) corresponding to each ionization line (9a).

  The plurality of ionization lines (9a) are arranged on the front side of the corrugated member (15) having a wave shape or a horizontal sectional shape in which a plurality of “U” characters are connected. In the present embodiment, two corrugated members (15) are arranged on the left and right. Further, a plurality of front openings (15a) are formed on the front side of the corrugated member (15), and each ionization line (9) has an upper end of the corrugated member (15) in each front opening (15a). It is stretched from the bottom to the bottom. On the other hand, the counter electrode (9b) corresponding to the ionization line (9a) is provided on the wall surface forming the front opening (15a) of the corrugated member (15). A mesh plate (19) arranged in parallel with the dust collecting filter (10) is connected to the rear surface of the corrugated member (15).

  The discharge device (11) includes a plurality of discharge electrodes (13) and a planar counter electrode (14) facing each discharge electrode (13).

  The discharge electrode (13) is formed in a line shape or a rod shape, and is disposed on the rear side of the corrugated member (15). As shown in FIG. 7 (A), which is an enlarged perspective view of the discharge device (11), the discharge electrode (13) is disposed in the rear opening (15b) of the corrugated member (15) and is vertically oriented. Is supported by an electrode holding member (20) extending in the vertical direction. The electrode holding member (20) is formed in a U-shaped horizontal section, and a plurality of support plates (20a) bent forward are formed at predetermined portions. The linear or rod-like discharge electrode (13) is supported by the tip of the support plate (20a) caulked so as to sandwich the discharge electrode (13) (FIG. 7 (B), discharge device). (See horizontal section of As described above, both end portions of the discharge electrode (13) protrude in the vertical direction from the support plate (20a). In the present embodiment, the discharge electrode (13) is made of tungsten. The wire diameter of the discharge electrode (13) is about 0.2 mm.

  On the other hand, the counter electrode (14) is formed on the first surface (rear surface) (15c) in the rear opening (15b) of the corrugated member (15) where the discharge electrode (13) is arranged in this way. Yes. The first surface (15c) functions as an electrode surface facing the discharge electrode (13). In this way, the discharge electrode (13) protruding from the support plate (13a) is disposed substantially parallel to the electrode surface of the counter electrode (14). A spacer (41) interposed between the counter electrode (14) and the electrode holding member (20) is provided at the upper end and the lower end of the counter electrode (14), respectively. This spacer (41) is formed of an insulating insulator in this embodiment. The distance (L) from the tip of the discharge electrode (13) to the counter electrode (14) is held at a constant interval by the spacer (41). In this embodiment, the distance (L) between the electrodes (13, 14) is 6.1 ± 0.3 mm.

  The electrostatic filter (10) described above is disposed on the downstream side of the discharge device (11). The electrostatic filter (10) collects relatively small dust charged by the ionization unit (9) described above on the upstream surface, while a photocatalyst (photosemiconductor) is supported on the downstream surface. Yes. This photocatalyst is further activated by highly reactive substances (active species such as electrons, ions, ozone, radicals, etc.) in the low temperature plasma generated by the discharge of the discharge device (11). Promotes decomposition of odorous substances. As the photocatalyst, for example, titanium dioxide, zinc oxide, tungsten oxide, cadmium sulfide, or the like is used. The electrostatic filter (10) is a so-called pleated filter formed by bending a horizontal section into a wave shape.

  The catalyst filter (12) is disposed on the downstream side of the electrostatic filter (10). This catalyst filter (12) carries a plasma catalyst on the surface of a substrate having a honeycomb structure. Like the photocatalyst, this plasma catalyst is further activated by a highly reactive substance (active species such as electrons, ions, ozone, radicals, etc.) in the low temperature plasma generated by the discharge of the discharge device (11), It promotes the decomposition of harmful substances and odorous substances that are treated components in indoor air. As the plasma catalyst, a manganese-based catalyst or a noble metal-based catalyst, and those obtained by adding an adsorbent such as activated carbon to these catalysts are used.

-Driving action-
During the operation of the air purification device (1), the centrifugal blower (40) is activated, and the indoor air, which is the gas to be treated, flows through the flow passage (6) in the casing body (2). In this state, a high voltage is applied from the power supply means (18) to the ionization section (9) and the discharge device (11).

  When indoor air is introduced into the casing body (2), first, relatively large dust is removed in the prefilter (8). The room air that has passed through the prefilter (8) flows to the ionization section (9). In the ionization section (9), relatively small dust in the indoor air is charged by the discharge between the ionization line (9a) and the counter electrode (9b). The room air containing the charged dust flows into the electrostatic filter (10). Then, in the electrostatic filter (10), these charged dusts are collected.

  On the other hand, in the discharge device (11), low temperature plasma is generated by streamer discharge between the discharge electrode (13) and the counter electrode (14). For this reason, the low-temperature plasma generated by the discharge device (11) flows downstream together with the room air.

  This low temperature plasma contains a highly reactive substance (active species). And this highly reactive substance contacts indoor air and decomposes harmful substances and odorous substances in the indoor air. Further, when the active species reach the electrostatic filter (10), it is further activated by the photocatalyst carried on the electrostatic filter (10), and further harmful substances and odor components in the indoor air are further decomposed. Further, when the active species reach the catalytic filter (12), these substances are further activated, and harmful substances and odorous substances in the indoor air are further decomposed.

  The clean indoor air from which dust is removed and harmful substances and odorous substances are removed as described above is taken into the centrifugal blower (40) and blown into the room from the air discharge port (5).

-Effect of Embodiment 2-
In the second embodiment, the distance (L) between the discharge electrode (13) and the counter electrode (14) in the discharge device (11) is 6.1 ± 0.3 mm, that is, 10 mm or less. As a result, the frequency of the streamer discharge sound can be set to 6 KHz or more. For this reason, the frequency of the discharge sound of the streamer discharge can be made larger than the frequency region sensitive to human hearing. Therefore, also in the second embodiment, noise during streamer discharge can be reduced.

  In the second embodiment, the rod-shaped discharge electrode (13) and the counter electrode (14) are arranged in parallel. Therefore, even if the tip of the discharge electrode (13) is worn by active species or fast electrons, the distance between the electrodes (13, 14) can be kept constant. Therefore, the distance (L) between the electrodes (13, 14) can be maintained at an optimum interval, and the above-described noise reduction effect can be reliably obtained. Further, by maintaining the distance between the electrodes (13, 14) at an optimum interval in this way, the stability of the streamer discharge can be improved.

  Furthermore, in Embodiment 2, even if the tip of the discharge electrode (13) is worn out, the tip shape of the discharge electrode (13) is not changed, so that the original discharge characteristics can be continuously maintained. Thus, streamer discharge can be further stabilized. Therefore, it is possible to prevent the occurrence of sparks and abnormal discharge due to the change in the tip shape of the discharge electrode (13).

<< Other Embodiments >>
The present invention may be configured as follows with respect to the above embodiment.

  For example, in Embodiment 1 described above, the discharge end (17) provided on the discharge electrode (13) is a flat plate having a triangular shape, but the shape of the discharge end (17) may be, for example, a quadrangular prism. However, it may be tapered so that the diameter decreases toward the tip.

  In the first embodiment, the discharge terminals (17) are arranged on both sides of the discharge substrate (16) to form the discharge electrode (13), and the counter electrode (14) is arranged on both sides of the discharge electrode (13). However, the discharge substrate (16) is not necessarily provided with the discharge ends (17) on both sides, and the discharge end (17) is provided on one side of the discharge substrate (16). You may arrange. In this case, the counter electrode (14) may be configured in the electrode frame (15) so as to face the discharge end (17) provided on one side of the discharge substrate (16).

  Furthermore, in the above embodiment, a DC voltage is applied as the discharge voltage of the power supply means (18), but an AC voltage or a pulse voltage may be applied in addition to the DC voltage.

  In the above embodiment, the catalyst filter (12) in which a plasma catalyst such as a manganese catalyst or a noble metal catalyst is supported on a base material is provided on the downstream side of the discharge device (11). However, an adsorption processing unit in which an adsorbent such as activated carbon or zeolite is supported on a base material may be provided on the downstream side of the discharge device (11) instead of the catalyst filter (12).

It is a disassembled perspective view of the air purification apparatus which concerns on Embodiment 1 of this invention. FIG. 2A is an enlarged view of a main part showing the electrode structure of the discharge device, and FIG. 2B is a front view of the main part of the discharge electrode. FIG. 2C is an enlarged view of a main part showing a modification of the electrode structure of the discharge device. It is a relationship figure of the distance between the discharge electrode and counter electrode at the time of streamer discharge, and the frequency of sound. 4 (A), 4 (B), and 4 (C) are explanatory views showing the mechanism of streamer discharge. It is a disassembled perspective view of the air purification apparatus which concerns on Embodiment 2 of this invention. It is the figure which looked at the inside of the air purification apparatus of Embodiment 2 from upper direction. FIG. 7A is an enlarged view of a main part showing an electrode structure of the discharge device, and FIG. 7B is a horizontal sectional view of the discharge device. It is the schematic of the discharge device in a prior art.

Explanation of symbols

(1) Air purification device
(11) Discharge device
(13) Discharge electrode
(14) Counter electrode
(17) Discharge end
(22) Charged particles
(L) Distance between discharge electrode and counter electrode

Claims (7)

A discharge electrode (13), a counter electrode (14) facing the discharge electrode (13), and a power supply means (18) connected to apply a discharge voltage to the electrodes (13, 14). ,
A discharge device for performing a streamer discharge between the electrodes (13, 14),
Both the electrodes (13, 14) are configured so that the frequency of the streamer discharge sound is 6 kHz or more. A discharge electrode (13), a counter electrode (14) facing the discharge electrode (13), and a power supply means (18) connected to apply a discharge voltage to the electrodes (13, 14). ,
A discharge device for performing a streamer discharge between the electrodes (13, 14),
The both electrodes (13, 14) are configured so that the remaining time of the charged particles (22) generated by the streamer discharge is 0.17 ms or less. A discharge electrode (13), a counter electrode (14) facing the discharge electrode (13), and a power supply means (18) connected to apply a discharge voltage to the electrodes (13, 14). ,
A discharge device for performing a streamer discharge between the electrodes (13, 14),
A discharge device, wherein a distance (L) between the discharge electrode (13) and the counter electrode (14) is 10 mm or less. The discharge device according to claim 1, 2, or 3,
The discharge electrode (13) has a plurality of protruding discharge ends (17),
The counter electrode (14) is formed in a plate shape,
A discharge device, wherein a tip end portion of a discharge end (17) of the discharge electrode (13) and an electrode surface of the counter electrode (14) are arranged to face each other. The discharge device according to claim 4, wherein
The discharge device according to claim 1, wherein the discharge end (17) of the discharge electrode (13) is formed in a flat plate shape. The discharge device according to claim 1, 2, or 3,
Discharge device characterized in that the discharge electrode (13) is formed in a linear or rod shape and is arranged substantially parallel to the counter electrode (14). An air purifier that vents a gas to be processed between the electrodes (13, 14) and processes the gas to be processed by a discharge device,
The said discharge apparatus is a discharge apparatus of any one of Claim 1 to 6, The air purification apparatus characterized by the above-mentioned.

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