Electrostatic dust collecting apparatus and manufacturing method of the same

Abstract: An electric dust collecting apparatus includes at least one needle electrode (28) for charging floating particles (5, 65) in air by generating corona discharge around needle points; at least one collecting electrode (26) provided on cell-liked arrangement corresponding to the needle electrodes, for attracting and collecting the charged floating particles by an electrostatic force; and at least one deflection electrode (29) having a rectangularly hollow longitudinal structure comprised of a front plate portion (29a) and side plate portions (29b, 29b) and fixed the needle electrodes on the front plate portion, for applying a deflection force to the charged floating particles to move toward the collecting electrodes by a potential applied from the side plate portions, wherein the at least one deflection electrode (29) having the rectangularly hollow longitudinal structure is obtained from bending a profile plate (31, 32) punched up a sheet metal (30) by a predetermined punch press process, accordingly, the plurality of deflection electrodes can be integratedly formed from a profile punched up a sheet metal by the punching and bending press process, enabling the manufacturing process to have workability and productivity.

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric dust collecting apparatus and manufacturing method of the same, more particularly to an electric dust collecting apparatus and manufacturing method of the same suitably used for such as an air cleaner, a black smoke removing apparatus for Diesel engine's exhaust and an oil-mist removing apparatus for use in factory. 2. Description of the Related Art Recently, buildings such as office buildings, restaurants, recreation facilities, factories, housings have a good air-tight structure, therefore, air stagnates in the buildings relatively. Such air contains smoke floating in the air caused by tobacco, toner come out from a copy machine, paper particles of copy papers and together with bad smell even toxic substance sometimes. This causes people in the buildings to impair their health and also makes the facilities and machines dirty. To this end, an electric dust collecting-type air cleaner has spread and installed in the buildings to collect floating particles such as smoke caused by tobacco and toner and remove bad smell from the air. In one of such air cleaner described above, there has been an air clear shown in Figs. 22 and 23. This air cleaner is of a wall-suspension type and has a pre-filter 1, an electrostatic-type dust collecting unit 2, a deodorizing filter 3 made up of an active carbon fiber and the like, a fan 4 such as cross-flow fan and the like and a power source which is not shown in the drawings. With operation of the air cleaner, a dirty air 5 contained, for example, floating particles of toner and smoke of tobacco is sucked into the inner portion of air cleaner from a suction opening 6 located close to a ceiling by a suction power of the fan 4. The dirty air 5 firstly passes through the pre-filter 1 to thereby collect relatively large floating particles. Subsequently, it flows into the dust collecting unit 2 where the floating particles is charged as corona electrification and collected in electrostatically. Finally, the air flows to the deodorizing filter 3 to be adsorbed and removed bad smell, then purified. The purified air 7 is then blown toward a floor from a blowing opening 8 by the discharging power of fan 4. In the case of air cleaner, the suction opening 6 is projected from the body of air cleaner, therefore, it is possible to circulate the air in a room effectively, so that the air is purified for a relatively short period of time. Referring to Figs. 24 to 26, the dust collecting unit 2 which is a major part of the air cleaner will be described below. Fig. 24 is a vertically sectional view showing the dust collector 2. Fig. 25 is a vertically sectional view showing an exploded view of the dust collector 2 as divided into two sub-units. Fig. 26 is a perspective view from seeing the front side (air suction side) of the dust collector 2. The dust collector 2 described above comprises a male-type sub-unit 11 having needle deflection coupled electrodes 10 as a needle-attached prism structure arranged with a multiple grating liked on the inner side of an outer case-liked frame 9; and a female-type sub-unit 14 having collector cells (collector electrodes) 13 like a rectangular pipe having both openings at the ends as an electrostatic dust collecting filter arranged with a multiple grating liked on the inner side of an inner case-liked frame 12. With both the frames 9 and 12 engaged with each other and incorporated thereinto, both the collector cells 13 and the needle deflection coupled electrodes 10 are oppositely arranged in one-to-one, that is, the needle deflection coupled electrodes 10, 10,... are attached into the collector cells 13, 13,... with non-contact arranged, respectively. It is noted that both the male-type sub-unit 11 and the female-type sub-unit 14 can be removed (or separated) from each other in consideration of convenience to handle those due to cleaning work and the like (referring to Fig. 25). The respective needle deflection coupled electrodes 10 have needle electrodes 15 for generating an ionized space area to charge the floating particles being passed through; and a prism-liked deflection electrodes (for example, approximately 10 mm in square and 5 to 6 cm in length) 16 formed of a rectangular pipe structure made up of a front plate portion and a side plate portion in which the front plate supports and fixes the needle electrodes 15 respectively, and for applying a deflection force to the floating particles charged by a potential applied from the side plate portion so as to be directed to the collector cells 13. The respective needle deflection coupled electrodes 10, 10,... are coupled with each other to have an equal potential through metal coupling members 17, 17,..., on the other hand, they are supported by the outer case-liked frame 9 through insulating joint plates 18, 18,..., electrically insulating those from outer case-liked the frame 9. It is noted that a high voltage (for example, 5 to 6 kV) is applied between the needle deflection coupled electrode 10 and the collector cell 13 during operation from a direct current high voltage power source which is not shown in the drawing so that the needle deflection coupled electrode 10 becomes a positive potential while the collector cell 13 becomes a negative potential with suitable electrical supply connected. Fig. 27 is an explanatory diagram for explaining operation of the air cleaner. As described the construction above, when applying a direct current high voltage to the needle deflection coupled electrode 10, a corona discharge is equally occurred around the needle point of needle electrode 15 continuously and stably to form the ionized space area 19. At this time, the dirty air 5 sucked into the dust collecting unit 2 by the fan 4 passes through the ionized space area 19, the oxygen having a low ionized energy is firstly ionized to become a positive ion. The positive ion then adheres to particles 20, 20,... caused by such as smoke of tobacco to give electric charge of the positive ion to the particles 20, 20,... When the particles 20, 20,... having the electric charge pass through between the following deflection electrode 16 and the collector cell 13, the particles 20, 20,... close to the collector cell 13 are adhered to the collector cell 13 having the negative potential while the particles 20, 20,... apart from a pole plate of the collector cell 13 are repelled toward the pole plate of collector cell 13 to be adhered thereto by the positive potential of the pole plate of deflection electrode 16, so that the particles as micro-size as 0.01 µm up to as relatively large as 10 µm can be collected effectively. Fig. 28(a) is a perspective view showing a record needle-liked pin member 150 made of a stainless steel which was used for the needle electrode 15. Also, the deflection electrode 16 is comprised of a pair of bent metal plate members 160, 160 having side plate portions bent to a U-liked groove shape and a front plate portion also bent to L-liked shape to be closed one opening end of the side plate portions, and both opening sides of the bent metal plate members 160, 160 are faced with each other to make a rectangularly hollow longitudinal portion as shown in Fig. 28(b). Referring to Fig. 28(b), the proximal end of pin member 150 is attached to an abutting portion of the front plate portions of bent metal plate members 160, 160 forming the rectangularly hollow longitudinal portion, and the proximal end of pin member 150 is then fixed by the silver solder G, making a needle deflection coupled electrode 10. However, since the dust collector 2 normally has 50 to 200 pieces of the needle deflection coupled electrodes 10, 10, ... itself; great number of hours are required to produce the needle deflection coupled electrodes 10, 10,... by using the method with use of the silver solder G, cost of manufacturing the air cleaner is high and productivity is low. In addition, since the needle electrode 15 is jointed to the abutting or joint portion of the front plate portions, unstable joint may be arisen to cause disadvantage. From JP03161059 dust collecting electrodes are known for use in electric dust collecting apparatus. These electrodes are provided to charge dusts in the air with a positive electricity by corona discharge so as to collect the dusts. The electrodes are formed into a plurality of honey comb-like constructions by bonding aluminium foil 2 to the entire surface of a non flammable paper. SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an electric dust collecting apparatus and manufacturing method of the same capable of reducing manufacturing cost and enhancing productivity, and also having a good impact resistance. According to the present invention, there is provided an electric dust collecting apparatus including a plurality of needle electrodes for charging floating particles in air by generating corona discharge around needle points; a plurality of cell-liked collecting electrodes provided in correspondence with the respective needle electrodes, for attracting and collecting the charged floating particles by electrostatic force; and a plurality of deflection electrodes each having a rectangularly hollow longitudinal structure comprised of a front plate portion and side plate portions and fixed the needle electrodes on the front plate portion, for applying a deflection force to the charged floating particles to move toward the collecting electrodes by a potential applied from the side plate portions, in which predetermined number of deflection electrodes is grouped into either several units or a single unit, each of the units has N (integer of 2 or greater) number of deflection electrodes each having the rectangularly hollow longitudinal structure coupled with a connecting portion therebetween, the rectangularly hollow longitudinal structures are obtained from a profile plate punched up a sheet metal and bent to form the side plate portions and front plate potion by a punch press process, thereby the rectangularly hollow longitudinal structures are arranged with a three-dimensional integrated piece fabricated. The N number of deflection electrodes each having the rectangularly hollow longitudinal structure in one unit may be coupled with the connecting portion therebetween, and the rectangularly hollow longitudinal structures may be obtained from the profile plate punched up the sheet metal and bent to form the side plate portions and front plate portion by the punch press process, thereby the rectangularly hollow longitudinal structures are arranged in series with the three-dimensional integrated piece fabricated. The N number of deflection electrodes each having the rectangularly hollow longitudinal structure in one unit may be coupled with the connecting portion therebetween, and the rectangularly hollow longitudinal structures may be obtained from the profile plate punched up the sheet metal and bent to form the side plate portions and front plate portion by the punch press process such that two connecting portions are opposite to each other after bending, thereby the rectangularly hollow longitudinal structures having a predetermined interval are arranged in series with the three-dimensional integrated piece fabricated. The needle electrodes may be arranged on substantially central positions on each of the front plates of the deflection electrodes in alignment. The N number of deflection electrodes each having the rectangularly hollow longitudinal structure in one unit may be coupled with the connecting portion therebetween; the rectangularly hollow longitudinal structures may be obtained from the profile plate punched up the sheet metal and bent to form the side plate portions and front plate portion by the punch press process, thereby the rectangularly hollow longitudinal structures are arranged in series with the three-dimensional integrated piece fabricated; and M number of units having the N number of deflection electrodes are provided and coupled through the connecting portions, thus M (integer of 2 or greater) times N number of deflection electrodes are provided. The N number of deflection electrodes each having the rectangularly hollow longitudinal structure in one unit may be coupled with the connecting portions therebetween; the rectangularly hollow longitudinal structures may be obtained from the profile plate punched up the sheet metal and bent to form the side plate portions and front plate portion by the punch press process, thereby the rectangularly hollow longitudinal structures are arranged in series with the three-dimensional integrated piece fabricated; and M number of units are provided and coupled through (M + 1) number of connecting portions, thus M (integer of 2 or greater) times N number of deflection electrodes are provided. The needle electrode having a needle portion and a body portion may be provided on each of the front plate portions of the deflection electrodes where needle electrode mounting holes open at a substantially central portion of the front plate portions, and each of the body portions may be engaged and tightly fixed to the needle electrode mounting hole with the needle electrode projected from the front plate portion. The needle electrode having a needle portion and a relatively thin body portion and a relatively thick body portion in order may be fixedly mounted on each of the front plate portions of the deflection electrodes where needle electrode mounting holes open at a substantially central portion of the front plate portions in which each of the relatively thin body portions of the needle electrodes is inserted into the needle electrode mounting hole from an outside of the front plate portion and caulked from an inside of the front plate portion. The needle electrode having a needle portion and a relatively thin body portion and a relatively thick body portion in order may be fixedly mounted on each of the front plate portions of the deflection electrodes where needle electrode mounting holes open at a substantially central portion of the front plate portions in which each of the relatively thin body portions of the needle electrodes is inserted into the needle electrode mounting hole from an outside of the front plate portion and fixed to the front plate portion by a brazing joint. The plurality of group electrodes may be integratedly provided and coupled with a pair of connecting portions and fixed the needle electrodes on the front plate portions of N number of deflection electrodes arranged in series; bottom parts of the plurality of group electrodes may be mechanically and electrically coupled with a plurality of comb-type coupling members; and the plurality of comb-type coupling members may be mechanically and electrically engaged with the pair of connecting portions. The plurality of group electrodes may be integratedly provided and coupled with a pair of connecting portions and fixed the needle electrodes on the front plate portions of N number of deflection electrodes arranged in series; and the plurality of group electrodes may be mechanically and electrically coupled by rod coupling members penetrated into coupling holes formed on the connecting portions with a predetermined interval opened, thereby the plurality of group electrodes are fixed by the rod coupling members in a complete piece. According to the present invention, there is also provided a method of manufacturing an electric dust collecting apparatus including a plurality of needle electrodes for charging floating particles in air by generating corona discharge around needle points; a plurality of cell-liked collecting electrodes provided in correspondence with the respective needle electrodes, for attracting and collecting the charged floating particles by electrostatic force; and a plurality of deflection electrodes each having a rectangularly hollow longitudinal structure comprised of a front plate portion and side plate portions and fixed the needle electrodes on the front plate portion, for applying a deflection force to the charged floating particles to move toward the collecting electrodes by a potential applied from the side plate portions, in which determining predetermined number of deflection electrodes into either several units or a single unit, each of the units has N (integer of 2 or greater) number of deflection electrodes each having the rectangularly hollow longitudinal structure coupled with a connecting portion therebetween; punching a single metal plate to have a profile plate of the rectangularly hollow longitudinal structures are obtained from a profile plate punched up a sheet metal; and bending the profile plate to form the rectangularly hollow longitudinal structures each having the side plate portion and the front plate portion by a punch press process, thereby the rectangularly hollow longitudinal structures are arranged with a three-dimensional integrated piece fabricated. The punching process applies to a sheet metal to have a profile plate of N number of rectangularly hollow longitudinal structures and bend the profile plate to form the rectangularly hollow longitudinal structures in series each having the side plate portion and the front plate portion coupled with the connecting portions therebetween by a punch press process, thereby N number of deflection electrodes each having the rectangularly hollow longitudinal structure in series are arranged with a three-dimensional integrated piece fabricated. The punching process applies to a sheet metal to have a profile plate of N number of rectangularly hollow longitudinal structures and bend the profile plate to form the rectangularly hollow longitudinal structures in series each having the side plate portion and the front plate portion coupled with the connecting potions therebetween by a punch press process, thereby the rectangularly hollow longitudinal structures are arranged in series with the three-dimensional integrated piece fabricated; and M number of units having the N number of deflection electrodes are provided and coupled through the connecting portions, thus M (integer of 2 or greater) times N number of the deflection electrodes are provided. As described the construction above, the plurality of deflection electrodes can be integratedly formed from a profile punched up a sheet metal by the punching and bending press process, enabling the manufacturing process to have good workability and productivity. The needle electrode can be fixed to the front plate potion of deflection electrodes by not only the brazing but also caulking and impact work, enhancing production rate of the needle electrode fabricated on the deflection electrode, in addition, the needle electrode can be inserted into the needle electrode mounting hole, causing good coupling between them to increase remarkable strength, also enhancing impact resistance against the mechanical and thermal interference. Consequently, low production cost and mass-production can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, advantages and features of the present invention will be more apparent from the following description taken in conjunction with the accompanying drawings in which: Fig. 1 is a plan view showing a profile portion of deflection electrodes for use in an electric dust collecting apparatus of an embodiment of the present invention; Fig. 2 is a perspective view showing a middle processed product of the deflection electrodes applied by punching and bending process; Fig. 3 is a perspective view showing a middle processed product of inserting needle electrodes; Fig. 4 is a perspective view showing a middle processed product having needle electrodes; Figs. 5(a) to 5(c) are perspective views and their sectional views showing steps of fabricating the needle electrode; Fig. 6 is a perspective view showing the deflection coupled electrodes having the needle electrodes; Fig. 7 is a perspective view showing a method of fabricating a male-type sub-unit having needle deflection coupled electrodes; Fig. 8 is a perspective view showing a method of fabricating a male-type sub-unit having the needle deflection coupled electrodes; Fig. 9 is a perspective view showing a method of fabricating a male-type sub-unit having the needle deflection coupled electrodes; Fig. 10 is a plan view showing a profile of a collector cell provided for each of the needle deflection coupled electrodes; Fig. 11 is a plan view showing an electrode wall plate; Fig. 12 is an enlarge view showing a part of Fig. 11; Fig. 13 is a partial perspective view showing a method of fabricating the collector cell; Fig. 14 is a partial perspective view showing a method of fabricating the collector cell; Fig. 15 is a partial perspective view showing a method of fabricating the collector cell; Fig. 16 is a perspective view showing a dust collecting unit in which the needle deflection coupled electrodes are fabricated with the collector cells; Figs. 17(a) to 17(c) are explanatory views showing a method of fabricating the needle electrode to the deflection electrode in a second embodiment of the present invention; Figs. 18(a) to 18(c) are explanatory views showing a method of fabricating the needle electrode to the deflection electrode in a third embodiment of the present invention; Fig. 19 is a perspective view showing a structure of male-type sub-unit in a fourth embodiment of the present invention; Fig. 20 is a perspective view showing a structure of the needle deflection coupled electrodes in a fifth embodiment of the present invention; Fig. 21 is a diagrammatic sectional view showing a structure of a black smoke removing apparatus for Diesel engine's exhaust in a sixth embodiment of the present invention; Fig. 22 is a perspective view showing an air cleaner for explaining a related art; Fig. 23 is a side view, partially cut away, of showing the air cleaner; Fig. 24 is a vertically sectional view showing a structure of the dust collecting unit of major part of the air cleaner; Fig. 25 is a vertically sectional view showing a male-type sub-unit and a female-type sub-unit of the duct collecting unit; Fig. 26 is a perspective view showing the front side of duct collecting unit: Fig. 27 is an explanatory view for explaining the operation of air cleaner; and Figs. 28(a) and 28(b) are perspective views showing a method of fabricating the needle deflection coupled electrode for explaining a related art. DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings. <First Embodiment> Figs. 1 to 4, 5(a) to 5(c) and 6 to 9 are explanatory views of a method of manufacturing major part of an air cleaner in a first embodiment of the present invention, concretely, of manufacturing a number of needle deflection coupled electrodes integratedly fabricated in series, in which Fig. 1 is a plan view of a profile portion punched up a sheet metal and indicating a two-dimensional shape of needle deflection coupled electrodes; Fig. 2 is a perspective view showing a middle processed product bent the profile portion by a punch press; Figs. 3 and 4 are perspective views showing a middle processed product of inserting needle electrodes; Figs. 5(a) to 5(c) are perspective views and their sectional views showing steps of fabricating the needle electrode; Fig. 6 is a perspective view showing the needle deflection coupled electrodes having the needle electrodes; Figs. 7 to 9 are perspective views showing the fabricating order of a male-type sub-unit having a number of needle deflection coupled electrodes. Figs. 10 to 15 are explanatory views showing a method of manufacturing a collector cell provided for each of the needle deflection coupled electrodes, in which Fig. 10 is a plan view showing a profile plate of the collector cell; Fig. 11 is a plan view showing an electrode wall plate; Fig. 12 is an enlarge view showing a part of Fig. 11; Figs. 13 to 15 are perspective views showing the fabricating order of the collector cell. Fig. 16 is a perspective view showing a dust collecting unit in which the needle deflection coupled electrodes are fabricated with the collector cells. Referring to Fig. 16, a dust collecting unit 21 is incorporated in an air cleaner of such a wall-hung type, a ceiling-suspended type, a floor-placed type and the like. The dust collecting unit 21 comprises a male-type sub-unit 24 having needle deflection coupled electrodes 23 arranged inside an outer case-liked frame 22 with a number of gratings arranged; and a female-type sub-unit 27 having collector cells (or collecting electrodes) 26 arranged inside an inner case-liked frame 25 with a number of gratings arranged. This is substantially similar to the dust collecting unit 2 shown in Fig. 26 in that both the frames 22 and 25 are engaged with each other to thereby arrange the collector cells 26, 26,... and the needle deflection coupled electrodes 23, 23,... in one-to-one, or each of the needle deflection coupled electrodes 23, 23,... is fixedly inserted into the collector cells 26, 26,... with non-contact arranged, and in that both the male-type sub-unit 24 and female-type sub-unit 27 are removable from each other. The needle deflection coupled electrode 23 comprises a needle electrode 28 for generating an ionized space area to electrically charge floating particles which move through the area; and a deflection electrode (for example, approximately 10 mm in square and 5 to 6 cm in length) 29 having a rectangularly hollow longitudinal structure made up of a front plate portion 29a and side plate portions 29b, 29b in which the front plate portion 29a fixes the needle electrode 28 and the side plate portions 29b, 29b applied by a predetermined potential apply a deflection force to the charged floating particles to be moved toward the collector cell 26. This is also similar to the needle deflection coupled electrode 10 shown in Fig. 27. On the other hand, as shown in Fig. 1, the deflection electrode 29 is formed by punching a sheet metal (for example, 0.5 mm thick) 30 to have profile portions 31 to be formed of a rectangularly hollow longitudinal structure. The side plate 29b', 29b',... and a triangular portion of the front plate 29a', 29a',... or respective profile portions 31, 31,... are vertically bent by a punch press process as shown in Figs. 2 and 6, which are different from the deflection electrode 16 having the pair of bent metal plate members 160, 160 abutted each other. Each of the front plate portions of the deflection electrodes 29, 29,... has a mounting hole h to be mounted the needle electrode 28, as shown in Figs. 1 and 3, which is fixedly mounted therein without using the brazing work as shown in Figs. 4 and 9, which is unique to realize high productivity. Each of the needle electrodes 28, 28,... is formed by stainless steel and comprised of a cylindrical-shaped body portion 28a and a needle portion 28b projected from the body portion 28a as an enlarged view shown in Fig. 5. In addition, the needle portion 28b is applied by nickel plating with 2 to 10 µm in thickness as a surface treatment for preventing it from oxidation. As shown in Figs. 6 to 9, 98 pieces of the needle deflection coupled electrodes 23, 23,..., or 7 columns times 14 pieces (Fig. 6) of the needle deflection coupled electrodes 23, 23,... are mounted on a single dust collecting unit 21. The 14 pieces of the needle deflection coupled electrode 23 as shown in Fig. 6 are integratedly arranged in series in which a pair of connecting portions 32, 32 are opposite to each other after bending the sheet metal 30 having the profile portions 31, 31,... along in a longitudinal direction thereof, that is, a column of needle deflection coupled electrode 33 is arranged with 7 columns in parallel, constituting a dust collecting unit 21. Referring to Figs. 1 to 6, a manufacturing method of the column of needle deflection coupled electrode 33 will be described next. First, a punch press line comprising a punch and die set is provided for producing a profile of the needle deflection coupled electrodes 33, 33,.... A sheet metal (for example, 0.5 mm in thickness) 30 such as stainless steel and the like or the profile of the electrodes 33, 33,... is punched up by the punch press line as shown in Fig. 1 in which 14 profile pieces of the deflection electrodes 29, 29,... are formed on the sheet metal 30 having a punching hole, a punching profile and a notch opened. The sheet metal 30 of the deflection electrodes 29, 29,... also has a layout such that the front plates 29a', 29a',... lie in the center of the sheet metal 30 on the longitudinal direction and side plates 29b', 29b',... lie in both sides of the front plates 29a', 29a',...in symmetry with respect to the front plates 29a', 29a',... The pair of connecting portions 32, 32 in parallel on the sheet metal 30 are also formed by the punch press process, so that 14 pieces of the deflection electrodes 29, 29,...are integratedly formed on the pair of connecting portions 32, 32 with a predetermined pitch arranged. The pair of connecting portions 32, 32 also have a plurality of rod penetrated holes p, p,... with a predetermined pitch arranged to be penetrated a rod coupled member (metal rod) 40. As shown in Fig. 1, two pairs of triangularly shaped notches (hereinafter, referred to as triangle notch) Ka, Ka,... are formed on the central part of the sheet metal 30 in the longitudinal direction. A pair of rectangularly shaped notches (hereinafter, referred to as rectangular notch) Kb, Kb,... are also formed on both the edge portions close to the connecting portions 32, 32. As shown in Fig. 2, two lines intersected in the longitudinal direction of the sheet metal 30 and extended from one ends of the rectangular notch Kb to the other ends of the rectangular notch Kb through the deep points of the triangle notches Ka, Ka are two bending lines to be bent such as the side plate 29b', 29b',... and the triangle pieces of the front plate 29a' are vertically bent, and as shown in Fig. 6, two lines extended through one deep points of the triangle notches Ka, Ka,... and the other deep points of the triangle notches Ka, Ka,... both in the longitudinal directions of the sheet metal 30 are two bending lines to be bent such that the pair of connecting portions 32, 32 are opposite to each other. Also, the length across rectangular notches Kb and Kb is approximately 10 mm. As described above, the mounting hole h is opened at each central portion of the front plate 29a', 29a',..., the diameter of mounting hole h is larger than that of the needle portion 28b of needle electrode 28, but smaller than that of the body portion 28a. As described two bending lines in the direction intersecting the longitudinal direction of the sheet metal 30 above, the punch press process is applied to those lines to be bent approximately 90 degrees so that 14 pieces of U-shaped middle processed portions 34, 34,... are formed integratedly together with the pair of connecting portions 32, 32 as shown in Fig. 2. Subsequently, the middle processed portions 34, 34,... remain facing upward, then the needle electrodes 28, 28,... are inserted into the mounting holes h, h,... from above, as shown in Figs. 3 and 5(a). At this time, since the diameter of needle portion 28b of the needle electrode 28 is smaller than that of the mounting hole h, the needle portion 28b is penetrated thereinto easily, but the diameter of body portion 28a is larger than that of the mounting hole h, to this end, the body portion 28a of needle electrode 28 is held by the mounting hole h, as shown in Figs. 3 and 5(b). An air hammer, which is not shown in the drawing, then applies impact to the back surface of body portion 28a to be driven into the mounting hole h. At this time, the mounting hole h is deformed by driving the body portion 28a thereinto, so that the body portion 28a of needle electrode 28 is tightly fixed on the mounting hole h with generation of resilient restitutive force and high friction as shown in Figs. 4 and 5(c). As described the process above, middle processed portions 35, 35,... having the needle electrodes are formed as shown in Fig. 4. Thereafter, the punch press process is applied to the two lines extended through the deep points of triangle notches Ka, Ka,... in the longitudinal direction of the sheet metal 30 or the middle processed portions 35, 35,... to be bent in approximately 90 degrees, thereby forming 14 pieces of the deflection electrodes 29, 29,... each having a rectangularly hollow longitudinal structure with an integratedly arranged in series and completing a column of needle deflection coupled electrode 33 as shown in Fig. 6. In the bending process described above, the punch or male punch may be used of an ordinary rectangular column type having four flat surfaces corresponding to the shape of deflection electrode 29 in the longitudinal direction, but may desirably be used of another rectangular column type having an acute angle at four edges 36, 36,... or four concave surfaces in the longitudinal direction, and the top surface of punch is also a concave surface having four vertexes of the acute angles as an enlarged view shown in Fig. 6, so that the dust collecting efficiency may be increases since the four edges along the rectangular column can be made sharp, which has found in experiment. Referring to Figs. 7 to 9, the fabrication of male-type sub-unit body 38 having 7 columns of needle deflection coupled electrodes 33, 33,... will be described next. As shown in Fig. 7, since a column of needle deflection coupled electrode 33 having 14 pieces of the needle deflection coupled electrodes 23, 23,... is provided for 7 columns thereof which are coupled electrically (or equally coupled potential), a plurality of comb-type coupling members 39, 39,... and rod coupling members (metal rod) 40, 40,... are fabricated to the 7 columns of needle deflection coupled electrodes 33, 33,... The comb-type coupling member 39, 39,... are formed by punching a sheet metal to have a profile plate having alternately arranged teeth portions 41, 41,... and bending it in the longitudinal direction for vertically forming the teeth portions in two columns. The teeth portions 41, 41,... of comb-type coupling member 39 are engaged with 7 columns of needle deflection coupled electrodes 33, 33,... from the bottom thereof. The case shown in Fig. 7 uses 5 pieces of comb-type coupling members in approximately equal intervals. In addition, referring to Fig. 8, since the electrically and mechanically coupled arrangement enhances the 7 columns of needle deflection coupling electrodes 33, 33,..., the rod coupling members 40, 40,... are tightly penetrated into the plurality of rod penetrated holes p, p,... formed on the pair of connecting portions 32, 32, so that the 7 columns of needle deflection coupled electrodes 33, 33,... are coupled with electrically and mechanically secured structure by the penetration of the rod coupling members 40, 40,..., completing the male-type sub-unit body 38 having the 7 columns of needle deflection coupled electrodes 33, 33,... as shown in Fig. 9. Thereafter, such completed male-type sub-unit body 38 is incorporated into the outer case-liked frame 22 (Fig. 16) through an insulating joint plate (not shown in the drawing), which constitutes the male-type sub-unit 24. Referring to Figs. 10 to 15, a manufacturing method of the collector cells 26, 26,... will be described below. The collector cells 26, 26,... are comprised of a plurality of rectangularly shaped electrode wall plates 42, 42..., each of which has slits 43, 43... with triangle notch portions D, D,... extended from a long edge of the plate 42 to nearly middle portion thereof as shown in Figs. 11 and 12. One number of electrode wall plates 42, 42... are engaged with the other number thereof 42, 42,...at the slits 43 of the one intersecting those of the other, therefore, grating-liked hollows are formed by engaging the one number of electrode wall plates 42, 42,... and the other number thereof 42, 42,..., which are referred to as collector cells 26, 26,..., each of which houses the needle deflection coupled electrode 23, as shown Figs. 14 and 15. Referring back to Figs. 11 and 12, the electrode wall plate 42 also has fastening holes q, q,... besides the slits 43, 43,... and each of the slits 43, 43,... has spines T, T,... along the slit 43 as shown in Fig. 12. The slits 43, 43,... are formed by a punch and die set comprising four sequential elongated oval-liked portions S and one triangle notch portion D, for punching a sheet metal 44 of 3 mm in thickness as shown in Fig. 10, in which the size of elongated oval-liked portion is approximately 7 mm long and 1 mm wide. Such punch and die set are provided two sets with a predetermined interval arranged in parallel on a base stage, and the sheet metal 44 is punched every two slits 43, 43 at one punch press process in the longitudinal direction thereof, forming the slits 43, 43,... each having a triangle notch D, a four elongated oval-liked portions S entirely designated by LS, and four pairs of spines T as shown in Fig. 12. The one number of electrode wall plates 42, 42,... and the other number thereof produced by the punch press process described above are easily fitted with each other at the triangle notch portions D, D,... and firmly engaged with each other at the spines T, T,... It should be noted that an interval between a pair of spines T, T of triangle notch portions D, D is 0.295 µm and that between a pair of spines T, T of the elongated oval-liked portions S, S,... is 0.295 µm as well. In addition, an interval between the pair of spines T, T is smaller than the thickness (0.3 mm in thickness) of electrode wall plate 42 by desirably as much as 3 to 20 µm. The length of slit 43 may also set to an approximately half width of the electrode wall plate 42 in consideration of fabricating the collector cells 26, 26,... The fastening holes q, q,... may be formed with the same punch press process for forming the slits 43, 43,... extended from the slits 43, 43,... to the other long edge of sheet metal 44 or electrode wall plate 42 in alignment, distance from the other long edge of the electrode wall plate 42 to a center of the fastening hole q may be approximately the same as the depth of triangle notch portion D, as shown in Fig. 12. Referring to Fig. 13, the fabrication of electrode wall plates 42, 42,... or the collector cells 26, 26,... will be described next. A plurality of electrode wall plates 42, 42,...are provided as a group G1 and those of electrode wall plates 42, 42,... are provided as a group G2. The group G1 is engaged to the group G2 from above at 100 to 135 degrees intersecting angle (or superior angle) between the groups G1 and G2, that is, a number of grating-liked rhombus cells are formed as shown in Fig. 14 and a number of square cells are then formed by an externally applied force from two opposite vertexes of the fabricated unit in a diagonal direction, completing the collector cells 26, 26,... as shown in Fig. 15. It is noted that the groups G1 and G2 can easily and firmly be engaged with each other since the interval between the spines T, T is smaller than the thickness of electrode wall plate 42 by as much as 3 to 20 µm, and also, a large force is not required for engaging both the groups G1 and G2. According to the fabrication of collector cells 26, 26,..., the 98 pieces of cells are formed in one unit which is incorporated into the inner case-liked frame 25, completing a female-type sub-unit 27 as shown in Fig. 16. The female-type sub-unit 27 and the male-type sub-unit 24 as described above are incorporated into the inner and outer case-liked frame 25 and 22 respectively, which are engaged with each other to constitute a dust collecting unit 21. As a dust collecting unit 21 shown in Fig. 16, the needle deflection coupled electrodes 23, 23,... correspond to the collector cells 26, 26,...respectively in which each of the needle deflection coupled electrodes 23, 23,... are attached to each of the collector cells 26, 26,... with non-contact arranged therein. It is noted that the male-type sub-unit 24 is removable from the female-type sub-unit 27. Such a dust collecting unit 21 is incorporated into an air cleaner in which the needle defection coupled electrodes 23, 23,... are electrically connected with the collector cells 26, 26,... so that the needle deflection coupled electrode 23 sets to positive potential while the collector cell 26 sets to negative potential during operation. Because of this, a high direct current voltage such as 5 to 6 kV is applied to the air cleaner. In such construction of the air cleaner, the plurality of deflection electrodes 29, 29,... comprising the dust collecting unit 21 as describe above are formed by punching and bending up a single sheet metal 30 to produce it integratedly and simultaneously, enhancing workability and productivity. The needle electrodes 28, 28,... are fixedly mounted on the deflection electrodes 29, 29,... by the impact without using the brazing work, so that the mounting work of needle electrode 28 is remarkably enhanced. The proximal end of needle electrode 28 is inserted and firmly fixed to the front plate portion 29a, so that the junction and impact resistance of those are remarkably enhanced. Referring back to Fig. 15, the pair of spines T, T are formed on the triangle notch portion D and the elongated oval-liked portions S, S,... on the slits 43, 43,..., therefore, excellent fastening effect acts on the electrode wall plates 42, 42,..., no displacement occurs and impact resistance of the collector cells 26, 26,... enhances. Totally, productivity and low cost of manufacturing the air cleaner can be achieved. Figs. 17(a) to 17(c) are diagrammatical explanatory views showing a method of mounting the needle electrode on the deflection electrode. The second embodiment different from the first embodiment is that the needle electrode 45 is fixed to the deflection electrode 29 by a caulking manner instead of by the impact and that the needle electrode 45 has a needle portion 45a, a relatively thick portion 45b and a relatively thin portion 45c instead of having the needle portion and body portion. Detailed descriptions of manufacturing those are omitted since the mostly same method in the first embodiment is involved in the second embodiment, therefore, the same reference numerals are designated on Figs. 17(a) to 17(c) as used on Figs. 5(a) to 5(c). The method of mounting the needle electrode 45 on the deflection electrode 29 will be described with reference to Figs. 17(a) to 17(c). In order of fixing the needle electrode 45 to the middle processed portions 34, 34,...(referring to Fig. 2) as shown in Fig. 17(a), the relatively thin portion 45c of needle electrode 45 is inserted into the mounting hole h, edge portion of which is bent toward the inner side of side plate 29b', and the needle electrode 45 is held by a tool which is not shown in the drawing. Subsequently, as shown in Fig. 17(b), an eccentric caulking tool 47 attaching to a high speed eccentric caulking machine 46 is rotatably abutted to the back surface of relatively thin portion 45c which is projected from the mounting hole h, thereby the relatively thin portion 45c is deformed to form a plasticized portion 45c', caulking the needle electrode 45 as shown in Fig. 17(c), therefore, the needle electrode 45 is no longer removed therefrom. The junction of the needle electrode 45 and deflection electrode 29 is secured by the caulking work, enhancing impact resistance, thermal resistance and durability of the apparatus. Figs. 18(a) to 18(c) are diagrammatical explanatory views showing a method of mounting the needle electrode 45 on the deflection electrode 29. Detailed descriptions of manufacturing those are omitted since the mostly same method in the second embodiment is involved in this embodiment, therefore, the same reference numerals are designated on Figs. 18(a) to 18(c) as used on Figs. 17(a) to 17(c). The needle electrode 45 is fixed to the front plate 29a' by the brazing work, enhancing uniformity of the junction quality and stabilization of dust collection. The needle electrode 45 is fixed to the middle processed portion 34, but may be fixed to a complete unit shown in Figs. 6 to 9, for example. Fig. 19 is a perspective view showing a male-type sub-unit body 48. The electrical and mechanical couplings between the needle deflection coupled electrodes 33, 33,... are realized only with the rod coupling members 40, 40,... instead of using the comb-type coupling members 39, 39,... in manufacturing process of the male-type sub-unit 48, referring to Fig. 8 which is previously described, so that the electrical and mechanical couplings can be obtained from only penetrating the rod coupling members 40, 40,... into the penetrating holes p, p,... formed on the connecting portions 32, 32, making fabrication work simple and reducing the number of processes. The comb-type coupling members 39, 39,... may also be used for realizing the electrical and mechanical coupling instead of using the rod coupling members 40, 40,... Fig. 20 is a perspective view showing two-column of needle deflection coupled electrode 49. The two-column of needle deflection coupled electrode 49 comprises two of needle deflection coupled electrodes 33, 33 (Fig. 6) coupled by a column coupling piece 50, each of the needle deflection coupled electrodes 33, 33 is formed by punching and bending up a single sheet metal, as described in the first embodiment. M (integer of 3 or more) number of needle deflection coupled electrodes 33, 33,... may be coupled by M + 1 number of column coupling pieces 50, 50,..., making a multi-column arrangement in one unit. Fig. 21 is a diagrammatic sectional view showing a structure of a black smoke removing apparatus for Diesel engine's exhaust. The black smoke removing apparatus comprises two dust collecting units 21, 21 mounted on an exhaust pipe 63 of a Diesel engine operated vehicle to collect a black smoke 65 in an exhaust 64, each of the dust collecting units 21, 21 is already described in the previously explained embodiments as to how they are produced and fabricated. In the case of this embodiment, the needle electrode 45 should desirably be fixed to the front plate 29a' by either the impact or the caulking work to ensure thermal resistance and durability. According to the embodiments described above, the number of needle deflection coupled electrodes 23, columns of needle deflection coupled electrodes 33, comb-type coupling members 39, and collector cells 26 may be changed in accordance with a scale of the apparatus. The shape of columns of needle deflection coupled electrodes 33 may be changed to an application depending on size and design. A single needle deflection coupled electrode 23 may be produced by punching and bending a single sheet metal. The shape of needle deflection coupled electrode 23 may be made not only a rectangularly hollow longitudinal structure but also a triangularly hollow longitudinal structure. A hammer machine may be used for caulking the relatively thin portion 45c instead of using the high speed eccentric caulking machine 46. The dust collecting unit 21 may be used for not only the black smoke removing apparatus, but also used for an oil-mist removing apparatus and an electrical dust collecting apparatus in a factory. It is thus apparent that the present invention is not limited to the above embodiments but may be changed and modified without departing from the scope and spirit of the invention. Finally, the present application claims the priority of Japanese Patent Application No. Hei9-70493 filed March 7, 1997, which is herein incorporated by reference.

Claims: An electric dust collecting apparatus including a plurality of needle electrodes (28, 28,...) for charging floating particles (5, 65) in air by generating corona discharge around needle points; a plurality of cell-liked collecting electrodes (26, 26,...) provided in correspondence with the respective needle electrodes, for attracting and collecting the charged floating particles by an electrostatic force; and a plurality of deflection electrodes (29, 29,...) each having a rectangularly hollow longitudinal structure comprised of a front plate portion (29a) and side plate portions (29b, 29b) and fixed the needle electrodes on the front plate portion, for applying a deflection force to the charged floating particles to move toward the collecting electrodes by a potential applied from the side plate portions, characterized in that predetermined number of deflection electrodes (29, 29,...) are grouped into either several units or a single unit, each of the units has N (integer of 2 or greater) number of deflection electrodes each unit having the rectangularly hollow longitudinal structures (31) coupled with connecting portions (32) therebetween; both being integral parts of a single unitary metal sheet (30) punched up and bent to form the side plate portions (29b) and front plate portions (29a) of the rectangularly hollow longitudinal structures. An electric dust collecting apparatus according to claim 1, characterized in that N number of group deflection electrodes (29, 29,...) each having the rectangularly hollow longitudinal structure in one unit are coupled with the connecting portion (32) therebetween, and that the rectangularly hollow longitudinal structures are made of the profile plate (31, 32) punched up the sheet metal (30) and bent to form the side plate portions (29b, 29b) and front plate portion (29a) by the punch press process, thereby the rectangularly hollow longitudinal structures are arranged in series with the three-dimensional integrated piece (33) fabricated. An electric dust collecting apparatus according to claim 2, characterized in that the N number of group deflection electrodes (29, 29,...) each having the rectangularly hollow longitudinal structure in one unit are coupled with the connecting portion (32) therebetween, and that the rectangularly hollow longitudinal structures are made of the profile plate (31, 32) punched up the sheet metal (30)and bent to form the side plate portions (29b, 29b) and front plate portion (29a) by the punch press process such that two connecting portions (32, 32) are opposite to each other after bending, thereby the rectangularly hollow longitudinal structures having a predetermined interval are arranged in series with the three-dimensional integrated piece (33) fabricated. An electric dust collecting apparatus according to claim 3, characterized in that the needle electrodes (28, 28,...) are arranged on substantially central positions on each of the front plates (29a, 29a,...) of the deflection electrodes (29, 29,...) in alignment. An electric dust collecting apparatus according to claim 1, characterized in that the N number of deflection electrodes (29, 29,...) each having the rectangularly hollow longitudinal structure in one unit are coupled with the connecting portion (32) therebetween; that the rectangularly hollow longitudinal structures are made of the profile plate (31, 32) punched up the sheet metal (30) and bent to form the side plate portions (29b, 29b) and front plate portion (29a) by the punch press process, thereby the rectangularly hollow longitudinal structures are arranged in series with the three-dimensional integrated piece (33) fabricated; and that M (integer of 2 or greater) number of units having the N number of deflection electrodes (29, 29,...) are provided and coupled through the connecting portions (32, 32) thus M times N number of deflection electrodes are provided. An electric dust collecting apparatus according to claim 5, characterized in that the N number of deflection electrodes (29, 29,...) each having the rectangularly hollow longitudinal structure in one unit are coupled with the connecting portions (32, 32) therebetween; that the rectangularly hollow longitudinal structures are made of the profile plate (31, 32) punched up the sheet metal (30) and bent to form the side plate portions (29b, 29b) and front plate portion (29a) by the punch press process, thereby the rectangularly hollow longitudinal structures are arranged in series with the three-dimensional integrated piece (33) fabricated; and that M (integer of 2 or greater) number of units are provided and coupled through (M + 1) number of connecting portions (32, 32,...), thus M times N number of deflection electrodes are provided. An electric dust collecting apparatus according to-one of claims 1 to 6, characterized in that the needle electrode (28) having a needle portion (28b) and a body portion (28a) is provided on each of the front plate portions (29a, 29a,...) of the deflection electrodes (29, 29,...) where needle electrode mounting holes (h, h,...) open at a substantially central portion of the front plate portions, and that each of the body portions are engaged and tightly fixed to the needle electrode mounting hole with the needle electrode projected from the front plate portion. An electric dust collecting apparatus according to one of claims 1 to 6, characterized in that the needle electrode (45) having a needle portion (45a) and a relatively thin body portion (45c) and a relatively thick body portion (45b) in order is fixedly mounted on each of the front plate portions (29a, 29a,...) of the deflection electrodes (29, 29,...) where needle electrode mounting holes (h, h,...) open at a substantially central portion of the front plate portions in which each of the relatively thin body portions of the needle electrodes (45) is inserted into the needle electrode mounting hole from an outside of the front plate portion and caulked from an inside of the front plate portion. An electric dust collecting apparatus according to one of claims 1 to 6, characterized in that the needle electrode (45) having a needle portion (45a) and a relatively thin body portion (45c) and a relatively thick body portion (45b) in order is fixedly mounted on each of the front plate portions (29a, 29a,...) of the deflection electrodes (29, 29,...) where needle electrode mounting holes (h, h,...) open at a substantially central portion of the front plate portions in which each of the relatively thin body portions of the needle electrodes is inserted into the needle electrode mounting hole from an outside of the front plate portion and fixed to the front plate portion by a brazing joint. An electric dust collecting apparatus according to claim 3 or 4, characterized in that the plurality of group electrodes (29, 29,...) are integratedly provided and coupled with a pair of connecting portions (32, 32) and fixed the needle electrodes (28, 28,...) on the front plate portions (29a, 29a,...) of N number of deflection electrodes arranged in series; that bottom parts of the plurality of group electrodes are mechanically and electrically coupled with a plurality of comb-type coupling members (39, 39,...); and that the plurality of comb-type coupling members are mechanically and electrically engaged with the pair of connecting portions (32, 32). An electric dust collecting apparatus according to claim 3 or 4, characterised in that the plurality of group electrodes (29, 29,...) are integratedly provided and coupled with a pair of connecting portions (32, 32) and fixed the needle electrodes (28, 28,...) on the front plate portions (29a, 29a,...) of N number of deflection electrodes arranged in series; and that the plurality of group electrodes are mechanically and electrically coupled by rod coupling members (40, 40,...) penetrated into coupling holes (p, p,...) formed on the connecting portions with a predetermined interval opened, thereby the plurality of group electrodes are fixed by the rod coupling members in a complete piece. A method of manufacturing an electric dust collecting apparatus including a plurality of needle electrodes (28, 28, ..) for charging floating particles (5, 65) in air by generating corona discharge around needle points; a plurality of cell-liked collecting electrodes (26, 26,...) provided in correspondence with the respective needle electrodes, for attracting and collecting the charged floating particles by electrostatic force; and a plurality of deflection electrodes (29, 29,...) each having a rectangularly hollow longitudinal structure comprised of a front plate portion (29a) and side plate portions (29b, 29b) and fixed the needle electrodes on the front plate portion, for applying a deflection force to the charged floating particles to move toward the collecting electrodes by a potential applied from the side plate portions, the method characterized by the steps of: determining a predetermined number of deflection electrodes (29, 29,...) into either several units or a single unit, each of the units has N (integer of 2 or greater) number of deflection electrodes each having the rectangularly hollow longitudinal structure coupled with a connecting portion (32) therebetween; punching a single metal plate (30) to have a profile plate (31, 32) of the rectangularly hollow longitudinal structures obtained from a profile plate punched up a sheet metal; and bending the profile plate to form the rectangularly hollow longitudinal structures each having the side plate portions (29b, 29b) and the front plate portion (29a) by a punch press process, thereby the rectangularly hollow longitudinal structures being fabricated in a three-dimensional integrated piece (33). A method according to claim 12, characterized in that the punching process applies to the sheet metal (30) to have the profile plate (31, 32) of N number of rectangularly hollow longitudinal structures and bend the profile plate to form the rectangularly hollow longitudinal structures in series each having the side plate portions (29b, 29b) and the front plate portion (29a) coupled with the connecting portions (32, 32) therebetween by a punch press process, thereby N number of deflection electrodes each having the rectangularly hollow longitudinal structure in series are arranged with a three-dimensional integrated piece (33) fabricated. A method according to claim 12, characterized in that the punching process applies to the sheet metal (30) to have the profile plate (31, 32) of N number of rectangularly hollow longitudinal structures and bend the profile plate to form the rectangularly hollow longitudinal structures in series each having the side plate portions (29b, 29b) and the front plate portion (29a) coupled with the connecting potions (32, 32) therebetween by a punch press process, thereby the rectangularly hollow longitudinal structures are arranged in series with the three-dimensional integrated piece (33) fabricated; and M number of units having the N number of deflection electrodes (29, 29,...) are provided and coupled through the connecting portions (32, 32,..), thus M (integer of 2 or greater) times N number of the deflection electrodes are provided.

Inventors: NOJIMA KOUZABUROU, NOJIMA, KOUZABUROU
Applicants: KABUSHIKI KAISYA O DEN, KABUSHIKI KAISYA O-DEN
Application year: 1998
Main classification: B03C3
IPC codes: B03C3