JP2014047659A - Blower unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a blower unit in which manufacturing man-hour is reduced, a pressure loss is reduced and efficiency is improved.SOLUTION: A blower unit 1 comprises a casing 3 which includes an air inlet 15 and an air outlet 17 and the sides of which are surrounded by a plurality of side faces 13; and a plug fan 5 accommodated within the casing 3. A width dimension Wo of the air outlet 17 provided on a bottom face 11 of the casing 3 is formed smaller than a separation distance Wc1 between a pair of opposing side faces 13, 13 among the plurality of side faces 13. Between the plug fan 5 within the casing 3 and the air outlet 17, a disc-shaped distributor 7 is disposed which has an outer diameter larger than an outer diameter Df of the plug fan 5 and the outer edge of which is formed circular.

Description

  The present invention relates to a blower unit.

  Conventionally, a plug fan that does not use a casing has been used for blowing air from an air conditioner (hereinafter referred to as an air conditioner) or cooling an industrial machine (for example, see Patent Document 1). The air conditioner shown in Patent Document 1 is a heat pump type air conditioner in which a plug fan is disposed in a fan chamber, and it is required to reduce the outer shape. For this reason, there is a restriction on the space of the fan chamber (air blowing unit), and there is a problem that the distance between the fan and the air outlet cannot be sufficiently secured and efficiency is lowered. In order to solve this problem, the conical curved surface guide is disposed in the vicinity of the duct connection port on the inner wall of the fan chamber.

JP 2005-16791 A

  However, such a conventional air conditioner is often manufactured in a so-called made-to-order design that is designed in accordance with the space of a building installation location. For this reason, the dimension of the fan chamber also changes according to the installation location, and a conical curved surface guide has to be prepared for each air conditioner. Further, further improvement in pressure loss and efficiency is desired.

  Therefore, the present invention provides a highly efficient air blowing unit with a small number of manufacturing steps and low pressure loss.

  A blower unit according to the present invention includes a housing having a suction port and a blower outlet, the side of which is surrounded by a plurality of side surfaces, and a plug fan housed inside the housing, and the housing In the blower unit, the width dimension of the air outlet provided on the bottom surface is formed smaller than the distance between the pair of opposing side surfaces among the plurality of side surfaces. A rectifying plate having an outer diameter larger than the outer diameter of the plug fan and having a circular outer periphery is disposed between the plug fan and the outlet in the casing.

  According to the blower unit according to the present invention, since the width dimension of the air outlet is smaller than the separation distance between the pair of side surfaces facing each other among the plurality of side surfaces, the inside of the housing includes a side surface and a bottom surface. A corner is formed at a site where the crosses. Accordingly, since the air blown from the plug fan travels along the side surface and hits the bottom surface of the corner portion, a vortex flow is formed, so that the wind speed distribution of the air discharged from the blower outlet becomes uneven for each part along the radial direction. Pressure loss increases.

  On the other hand, in this invention, since the baffle plate is arrange | positioned, an eddy current becomes small compared with the case where there is no baffle plate by rectifying the flow of the air blown from the plug fan. Accordingly, the wind speed distribution of the air discharged from the outlet is uniform for each portion along the radial direction, and the pressure loss is reduced. In addition, since only the current plate is provided, the number of manufacturing steps can be reduced.

FIG. 1 is a perspective view showing a blower unit according to a first embodiment of the present invention, in which the side wall on the front side constituting the housing is omitted. FIG. 2 is a perspective view showing the plug fan and the disc-shaped rectifying plate of FIG. FIG. 3 is a perspective view showing the disc-shaped rectifying plate according to the first embodiment. FIG. 4 is a perspective view showing an annular rectifying plate according to the second embodiment. FIG. 5 is a perspective view showing a truncated cone-shaped rectifying plate according to the third embodiment. FIG. 6 is a schematic view showing the air flow in the housing according to the first embodiment. FIG. 7 is a schematic view showing the air flow in the housing according to the second embodiment. FIG. 8 is a schematic view showing the air flow in the housing according to the third embodiment. FIG. 9 is a schematic diagram illustrating the air flow in the housing according to the comparative example. FIG. 10 is a graph showing the relationship between the air volume and the static pressure for the inventive example and the comparative example. FIG. 11 is a graph showing the relationship between the air volume and the static pressure efficiency for the present invention example and the comparative example. FIG. 12 is a graph showing the relationship between the air volume and the static pressure for the present invention example and the comparative example, in which the inner and outer diameters of the annular rectifying plate are variously changed. FIG. 13 is a graph showing the relationship between the air volume and the static pressure efficiency for the present invention example and the comparative example, in which the inner and outer diameters of the annular rectifying plate are variously changed. FIG. 14 is a graph showing the relationship between the air volume and the static pressure in the present invention example and the comparative example, and the outer diameter of the annular rectifying plate is variously changed. FIG. 15 is a graph showing the relationship between the air volume and the static pressure efficiency for the examples of the present invention and the comparative example, and the outer diameter of the annular rectifying plate is variously changed. 16A is a perspective view showing dimensions of the plug fan and the truncated cone-shaped rectifying plate, and FIG. 16B is a graph showing the airflow and static pressure of the present invention and the comparative example. It is a graph which shows a relationship. FIG. 17 is a graph showing the relationship between the air volume and the static pressure efficiency for the inventive example and the comparative example.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[First embodiment]
As shown in FIG. 1, the blower unit 1 according to the first embodiment of the present invention includes a housing 3, a plug fan 5, and a disc-shaped rectifying plate 7 (rectifying plate).

  The casing 3 is formed in a rectangular parallelepiped box, and is composed of an upper surface 9 disposed on the upper side, a bottom surface 11 disposed on the lower side, and four side surfaces 13 surrounding the sides from four sides. ing. In FIG. 1, the front side surface 13 is omitted in order to clearly show the inside of the housing 3. A circular hole is formed at the center of the upper surface 9, and this hole serves as an air inlet 15. A rectangular hole is formed in the bottom surface 11, and this hole is a blower outlet 17. A rectangular tube-shaped duct 19 is connected to the lower side of the air outlet 17.

  Here, the size of the upper surface 9 is set such that the width dimension in the horizontal direction is Wc1 and the depth dimension in the front-rear direction is Wc2. Therefore, the separation distance between the pair of side surfaces 13 and 13 facing in the left-right direction is also set to Wc1. Wc1 is preferably 1134 mm, for example, and Wc2 is preferably 1134 mm, for example. Moreover, the height of the side surface 13 is set to Hc, and Hc is preferably 850 mm, for example. The width dimension Wo of the outlet 17 is preferably 630 mm, for example. And the width dimension Wo of the blower outlet 17 is set smaller than the separation distance Wc1 of the side surfaces 13 and 13. FIG.

  As shown in FIGS. 1 and 2, the plug fan 5 is opposed to a disk-shaped main plate 21 disposed on the lower side and spaced upward from the main plate 21 at a predetermined interval, and has an intake port in the center. And a plurality of blades 27 arranged between the main plate 21 and the side plate 25 at a predetermined interval along the circumferential direction. The main plate 21, the side plate 25, and the blades 27 are all formed by press-molding a steel plate panel or an aluminum plate, and are joined together by welding, caulking, or the like. The material is not limited to a steel plate or aluminum, and may be a resin or the like. The plug fan 5 is rotated by a motor 29 disposed on the lower side, whereby air A is blown out from the side of the plug fan 5. The motor 29 is supported by the housing 3.

  As shown in FIG. 2, the outer diameter of the side plate 25 (the outer diameter of the plug fan 5) is set to Df, and the inner diameter of the side plate 25 is set to df. The height of the plug fan 5 is set to Hf. For example, Df is preferably 630 mm, df is 440 mm, and Hf is 260 mm.

  Inside the housing 3, a disc-shaped rectifying plate having an outer diameter larger than the outer diameter of the plug fan 5 and having a circular outer periphery between the plug fan 5 and the outlet 17. 7 (rectifier plate) is arranged. The vertical distance between the lower end of the plug fan 5 and the disc-shaped rectifying plate 7 is h, and this h is preferably 50 mm, for example.

  As shown in FIG. 3, the disc-shaped rectifying plate 7 (rectifying plate) is a disc whose outer diameter is set to Dpa, and the outer diameter Dpa is formed larger than the outer diameter Df of the plug fan 5. ing. Specifically, the outer diameter Dpa of the disc-shaped rectifying plate 7 is set to 150 to 170% of the outer diameter Df of the plug fan 5. That is, Dpa = 1.5 Df to 1.7 Df. The disc-shaped rectifying plate 7 is supported on the side surface 13 of the housing 3 via four support legs 31 (partially not shown). In the present embodiment, the material of the disc-shaped rectifying plate 7 is a steel plate, but may be a resin or the like.

  In the blower unit 1 having the above-described configuration, air A is taken in from the suction port 15 formed in the upper surface 9 of the housing 3, and this air A enters the plug fan 5 from the air suction port 23 along the rotating blades 27. After being discharged to the side, it wraps around from the side of the outer peripheral edge of the disc-shaped rectifying plate 7 and flows into the duct 19 from the outlet 17 formed in the bottom surface 11.

[Second Embodiment]
Next, the second embodiment will be described, but the description of the same structure as that of the first embodiment described above will be omitted.

  In the second embodiment, an annular rectifying plate 41 (rectifying plate) is disposed instead of the disc-shaped rectifying plate 7 with respect to the blower unit 1 of the first embodiment described in FIG. The position where the annular rectifying plate 41 is arranged is the same as in the first embodiment.

  As shown in FIG. 4, the annular rectifying plate 41 is formed in a flat plate shape, and has an outer diameter of Dpb and an inner diameter of dpb. Both the outer peripheral edge and the inner peripheral edge are formed in a circular shape in plan view, and the center of the annular rectifying plate 41 coincides with the central axis of the plug fan 5. As described above, the annular rectifying plate 41 is formed in a flat plate shape in which the circular hole 41a is formed in the central portion of the disc.

  Further, the outer diameter Dpb of the annular rectifying plate 41 is formed larger than the outer diameter Df of the plug fan 5. Specifically, the outer diameter Dpb of the annular rectifying plate 41 is set to 150 to 170% of the outer diameter Df of the plug fan 5. That is, Dpb = 1.5 Df to 1.7 Df.

  The dimensional difference (Dpb−dpb) between the outer diameter Dpb and the inner diameter dpb of the annular rectifying plate 41 is set to 20 to 60% of the outer diameter Df of the plug fan 5. Specifically, (Dpb−dpb) = 0.2 Df to 0.6 Df.

[Third embodiment]
Next, the third embodiment will be described, but the description of the same structure as the first and second embodiments described above will be omitted.

  In the third embodiment, a truncated cone-shaped rectifying plate 51 (rectifying plate) is provided instead of the disc-shaped rectifying plate 7 with respect to the blower unit 1 of the first embodiment described in FIG. The position where the frustoconical rectifying plate 51 is arranged is the same as in the first embodiment.

  As shown in FIG. 5, the circular truncated conical plate 51 is formed with a circular hole 51a at the center, and the downstream side of the air flow (lower side in FIG. 5) as the side surface 53 moves from the center toward the outer periphery. It is formed in a truncated cone shape that inclines toward. The outer diameter is set to Dpc and the inner diameter is set to dpc. In addition, the inclination angle θ formed by the side surface 53 with the horizontal plane in a side view is preferably 0 ° to 20 °.

  The outer diameter Dpc of the truncated cone-shaped rectifying plate 51 is formed larger than the outer diameter Df of the plug fan 5. Specifically, the outer diameter Dpc of the truncated cone-shaped rectifying plate 51 is set to 150 to 170% of the outer diameter Df of the plug fan 5. That is, Dpc = 1.5 Df to 1.7 Df.

  Next, the present invention will be described in more detail through examples.

[First embodiment]
First, as shown in FIG. 6, the air flow in the housing 3 was simulated when the disc-shaped rectifying plate 7 was disposed below the plug fan 5 in correspondence with the first embodiment described above. A side of the housing 3 is surrounded by a side surface 13, and an air outlet 17 is formed at the center of the bottom surface 11. The dimension of the blower outlet 17 is formed smaller than the separation distance of a pair of side surfaces 13 and 13 which opposes. Note that a corner portion 14 defined by the lower portion of the side surface 13 and the outer peripheral portion of the bottom surface 11 is formed at the bottom portion of the housing 3.

As simulation software, ANSYS Fluent (registered trademark) was used, and the air volume was set to 14000 m ³ / h. A plurality of arrows indicate the magnitude and direction of the flow of air A in each part in the housing 3, the black circle indicates the position of the measurement point, the length of the arrow indicates the magnitude of the wind speed, and the direction of the arrow indicates Indicates the direction of air flow.

  After the air A is blown out from the plug fan 5 to the side, the air flows around the outer peripheral side of the disc-shaped rectifying plate 7 downward, and the disc-shaped rectifying plate 7, the side surface 13 and the bottom surface 11 of the housing 3. Weak eddy currents 61 and 63 are formed in a portion surrounded by. That is, as compared with the comparative example of FIG. 9 described later, the flow velocity of the air A constituting the vortex flows 61 and 63 is smaller. In FIG. 6, since the cross section is shown, it seems that the pair of right and left vortex flows 61 and 63 are generated, but the vortex flows 61 and 63 are integrally formed in an annular shape along the circumferential direction. And in the blower outlet 17 of the bottom face 11, the air A of the substantially the same direction and the substantially same magnitude | size is blown off to each site | part along the width direction at substantially equal intervals. Thus, the wind speed distribution at the outlet 17 is improved and the pressure loss is reduced.

[Second Embodiment]
Next, as shown in FIG. 7, the flow of the air A in the housing 3 in the case where the annular rectifying plate 41 is disposed below the plug fan 5 was simulated in correspondence with the second embodiment described above. The simulation conditions are the same as in the first embodiment.

  After the air A is blown out from the plug fan 5 to the side, the air flows around the outer periphery of the annular rectifying plate 41 and is surrounded by the annular rectifying plate 41, the side surface 13 and the bottom surface 11 of the housing 3. Weak eddy currents 65 and 67 are formed at the parts to be formed. In addition, air A flows downward from the hole in the center of the annular rectifying plate 41. Here, the air flow on the inner peripheral side of the vortex flows 65 and 67 is directed upward, and the air flow flowing from the hole at the center of the annular rectifying plate 41 is directed downward. Is smaller than that of the first embodiment. And in the blower outlet 17 of the bottom face 11, the air A of the substantially the same direction and the substantially same magnitude | size is blown off by the substantially equal space | interval in the wide range of the center part of radial direction. In this way, the wind speed distribution at the outlet 17 becomes even better than in the first embodiment, and the pressure loss is reduced.

[Third embodiment]
Next, as shown in FIG. 8, the flow of the air A in the housing 3 was simulated in the case where the truncated cone-shaped rectifying plate 51 was disposed below the plug fan 5 in correspondence with the third embodiment described above. The simulation conditions are the same as in the first and second embodiments.

  After the air A is blown out from the plug fan 5 to the side, the air flows around the outer peripheral side of the truncated cone-shaped rectifying plate 51 downward, and the truncated cone-shaped rectifying plate 51, the side surface 13 and the bottom surface 11 of the housing 3 Weak eddy currents 69 and 71 are formed in the region surrounded by. And in the blower outlet 17 of the bottom face 11, the air A of the substantially the same direction and the substantially same magnitude | size is blown off by the substantially equal space | interval in the wide range of the center part of radial direction. As described above, the wind speed distribution at the outlet 17 is further improved than in the first and second embodiments, and the pressure loss is also reduced.

[Comparative example]
Next, as shown in FIG. 9, as a comparative example, the flow of air A in the housing 3 in the case where the rectifying plate is not disposed below the plug fan 5 was simulated. The simulation conditions are the same as those in the first to third embodiments.

  After the air A is blown out from the plug fan 5 to the side, the portion surrounded by the plug fan 5 and the side surface 13 and the bottom surface 11 of the housing 3 is larger than the first to third embodiments and has a wind speed. Eddy currents 73 and 75 are formed. And in the blower outlet 17 of the bottom face 11, a wind speed is small in the center part of radial direction, and a wind speed becomes large in the outer side of the width direction. Thus, the wind speed distribution at the outlet 17 becomes more uneven than in the first to third embodiments, and the pressure loss increases. In addition, it can be confirmed that a portion 77 where the wind speed is particularly large is generated in the vicinity of the lower right of the plug fan 5, and it is estimated that a pressure loss is generated in this portion.

[Relationship between static pressure and static pressure efficiency and air flow]
Below, the relationship between static pressure and static pressure efficiency, and an air volume is demonstrated using FIGS. The simulation software used was ANSYS Fluent.

  10 and 11, “Without current plate 1008 hole” indicates a case where a disk-shaped current plate having an outer diameter of 1008 mm is used (example of the present invention), and “With current plate 1008-750 holes” is outside. A case where an annular rectifying plate (example of the present invention) having a diameter of 1008 mm and an inner diameter of 750 mm is used is shown. The “comparative example (cited document)” indicates a case where the conical curved surface guide of the cited document 1 cited in the background art is used, and the “comparative example (without rectifying plate) indicates a case where a rectifying plate is not provided. 10 and 11, it was found that the inventive example shows higher static pressure and static pressure efficiency than the comparative example in almost all the air volume ranges.

  12 and 13, the annular current plate (example of the present invention) and the comparative example were compared. In addition, about the magnitude | size of the annular current plate, it changed into three types with an inner diameter of 625 mm, 750 mm, and 875 mm with respect to an outer diameter of 1008 mm. Further, the inner diameter was changed to three types of 625 mm, 750 mm, and 875 mm with respect to the outer diameter of 945 mm. As shown in FIGS. 12 and 13, it was found that the inventive example shows higher static pressure and static pressure efficiency than the comparative example in almost all airflow ranges.

  In FIG. 14 and FIG. 15, the annular current plate (example of the present invention) and the comparative example were compared. Regarding the size of the annular rectifying plate, the inner diameter was changed to three types, that is, the outer diameter was 819 mm, 882 mm, 945 mm, and 1008 mm with respect to 750 mm. As shown in FIGS. 14 and 15, it was found that the inventive example shows higher static pressure and static pressure efficiency than the comparative example in almost all air volume ranges.

  16 and 17, the frustum-shaped rectifying plate 51 (example of the present invention) was compared with the comparative example. As shown in FIG. 16A, the truncated conical rectifying plate 51 is disposed 50 mm below the plug fan 5. Regarding the size of the truncated cone-shaped rectifying plate 51, the outer diameter was 1008 mm and the inner diameter was 750 mm. The inclination angle of the side surface 53 was changed to 0 ° (no inclination), 10 °, and 20 °. As shown in FIGS. 16B and 17, it was found that the inventive example shows higher static pressure and static pressure efficiency than the comparative example in almost all airflow ranges.

  By the way, although this invention was demonstrated taking the example in the said embodiment, the dimension of each part of this air blow unit 1 shows a similar characteristic in a similar air blow unit, and static pressure according to the proportional law of a fan, Since the values of the static pressure efficiency and the air volume can also be estimated, the present invention is not limited to this embodiment, and various modifications can be made without departing from the scope of the present invention.

  Next, the function and effect of this embodiment will be described.

(1) The blower unit 1 according to the present embodiment has a suction port 15 and a blower port 17, and a housing 3 whose side is surrounded by a plurality of side surfaces 13 and a plug accommodated in the housing 3. The width dimension Wo of the blower outlet 17 provided on the bottom surface 11 of the housing 3 is smaller than the separation distance Wc1 between the pair of side surfaces 13 and 13 facing each other among the plurality of side surfaces 13. Is formed. A rectifying plate (disc-shaped) having an outer diameter larger than the outer diameter Df of the plug fan 5 and a circular outer periphery between the plug fan 5 and the air outlet 17 in the housing 3. A rectifying plate 7, an annular rectifying plate 41, and a truncated cone rectifying plate 51) are arranged.

  Since the width dimension Wo of the blowout port 17 is smaller than the separation distance Wc1 between the pair of side surfaces 13 and 13 facing each other among the plurality of side surfaces 13, the side surface 13 and the bottom surface 11 are provided inside the housing 3. A corner portion 14 is formed at a portion where the two intersect. Therefore, since the air A blown out from the plug fan 5 hits the bottom surface 11 of the corner portion 14 through the side surface 13 and forms a vortex, the wind speed distribution of the air A discharged from the blowout port 17 is along the radial direction. The pressure loss increases because of unevenness in each part.

  On the other hand, in the present invention, since the rectifying plates 7, 41, 51 are arranged, the flow of the air A blown from the plug fan 5 is rectified, so that the vortex flow is compared with the case where there is no rectifying plate. Becomes smaller. Therefore, the wind speed distribution of the air A discharged from the blower outlet 17 is uniform for each part along the radial direction, and the pressure loss is reduced.

(2) The rectifying plate is a disc-shaped rectifying plate 7 formed in a disc. Thus, since the current plate has a very simple shape, the number of manufacturing steps can be reduced.

(3) The rectifying plate is an annular rectifying plate 41 in which a circular hole 41a is formed at the center of the disc. Thus, since the current plate has a very simple shape, the number of manufacturing steps can be reduced. Further, as described in the second embodiment, the air flow on the inner peripheral side of the vortex flows 65 and 67 is directed upward, and the air flow flowing from the hole 41a in the central portion of the annular rectifying plate 41 is directed downward. Both cancel each other, and the size of the vortices 65 and 67 is further reduced.

(4) The baffle plate has a circular truncated cone shape formed in a circular truncated cone shape in which a circular hole 51a is formed in the central portion and the side surface 53 is inclined toward the downstream side of the air flow from the central portion toward the outer periphery. This is a current plate 51. Accordingly, the air A blown from the plug fan 5 flows obliquely along the inclined side surface 53 and also flows downstream from the hole 51a in the central portion, so that the vortex is further reduced.

(5) The outer diameter (Dpa, Dpb, Dpc) of the current plate is set to 150 to 170% of the outer diameter Df of the plug fan 5. When it is less than 150%, the outer diameter of the rectifying plate is too small, and the rectifying effect of the air A by the rectifying plate is reduced. On the other hand, if it exceeds 170%, the outer diameter of the rectifying plate becomes too large, and the gap between the rectifying plate and the side surface 13 of the housing 3 becomes too small, and the flow rate of the air A flowing downstream from the gap is reduced. Increases, pressure loss increases and performance decreases.

(6) The dimensional difference (Dpb−dpb) between the outer diameter Dpb and the inner diameter dpb of the annular rectifying plate 41 is set to 20 to 60% of the outer diameter Df of the plug fan 5. When the dimensional difference (Dpb−dpb) of the annular rectifying plate 41 is less than 20% of the outer diameter Df of the plug fan 5, the area to be rectified by the annular rectifying plate 41 becomes too small, and the rectifying effect is insufficient. On the other hand, if it is larger than 60%, the amount of the air A passing through the central hole is too small, and the effect of reducing the vortex is reduced.

(7) The inclination angle θ of the side surface 53 of the truncated conical rectifying plate 51 is set to 0 to 20 ° in a side view. When the inclination angle θ is larger than 20 °, the side surface 53 is too close to the vertical direction, and the rectifying effect of the air A is reduced.

DESCRIPTION OF SYMBOLS 1 ... Air blow unit 3 ... Housing 5 ... Plug fan 7 ... Disc-shaped rectifier (rectifier)
DESCRIPTION OF SYMBOLS 13 ... Side surface 15 ... Suction inlet 17 ... Outlet 41 ... Annular rectifying plate (rectifying plate)
51 ... frustoconical rectifying plate (rectifying plate)
53 ... Side

Claims (7)

An air outlet provided on a bottom surface of the housing, including a housing having a suction port and an air outlet, the side of which is surrounded by a plurality of side surfaces, and a plug fan accommodated in the housing Is a blower unit formed with a width dimension smaller than a distance between a pair of opposing side surfaces among the plurality of side surfaces,
A blast plate having an outer diameter larger than the outer diameter of the plug fan and a circular outer periphery formed between the plug fan and the outlet in the casing. unit.   The blower unit according to claim 1, wherein the current plate is a disk-shaped current plate formed on a disk.   The blower unit according to claim 1, wherein the current plate is an annular current plate in which a circular hole is formed in a central portion of the disk.   The baffle plate is a frustoconical baffle plate formed in a truncated cone shape with a circular hole formed in the center and a side surface inclined toward the downstream side of the air flow from the center toward the outer periphery. The blower unit according to claim 1, wherein:   The blower unit according to any one of claims 1 to 4, wherein an outer diameter of the rectifying plate is set to 150 to 170% of an outer diameter of the plug fan.   The blower unit according to claim 3, wherein a dimensional difference between an outer diameter and an inner diameter of the annular rectifying plate is set to 20 to 60% of an outer diameter of the plug fan.   The blower unit according to claim 4, wherein an inclination angle of a side surface of the truncated conical plate is set to 0 to 20 ° in a side view.

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