Fan filter unit

Abstract

To uniform a flow-in distribution of air discharged from a fan 15 into a filter 40, and to suppress a variation of a wind velocity of clean air, in a fan filter unit 1.SOLUTION: In the fan filter unit 1 which has a turbo fan 10 rotationally driven by a motor 20, the filter 40, and an FFU case 30 for accommodating the filter 40 and the turbo fan 10, and in which the FFU case 30 has an air suction opening 31a and an air discharge opening face 33, rectification means 50 in which a plurality of rectification plates are aligned so that a length in a vertical direction is regularly shortened as approaching an axial line A1 from a position separated from one direction (longitudinal direction) of a horizontal direction from the axial line A1 is provided in a space between the turbo fan 10 and the filter 40.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a fan filter unit. [Background technology]

[0002] Air purifiers known as fan filter units (hereinafter referred to as "FFUs" in this specification) are widely used in environments requiring cleaner air, such as the ceilings of clean rooms where semiconductor wafers, liquid crystal panels, and other devices are manufactured, or in specific areas of manufacturing equipment within the clean room. An FFU uses an electric fan to draw in and pressurize air from outside the space to be cleaned. The air expelled from the fan into a case is then passed through a filter to blow clean air into a specific room (clean room), ensuring that airborne particles and airborne microorganisms meet a specified cleanliness level. An FFU is comprised of a blower such as a turbofan, a drive means (motor) for rotating the fan, a case that houses the fan and motor and has an air inlet and outlet, and a filter attached to the exhaust side of the turbofan. Patent Document 1 discloses an example of such an FFU.

[0003] Patent Document 1 discloses an FFU with an intake port formed in the top of a case (chamber), a fan unit built into the case, a filter disposed downstream of the fan unit, and a punched plate between the intake side of the filter and the fan unit. The punched plate has round holes with a diameter of about 1 mm and a hole pitch of about 2 mm all over its surface, and a punched plate with a round hole in the center and a shape that is inclined in the blowing direction from the outer periphery of the chamber toward the center. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-257645 Summary of the Invention [Problem to be solved by the invention]

[0005] When a centrifugal fan such as a turbofan is used as the fan unit, the flow direction of the fan's exhaust port is perpendicular to the rotation axis direction relative to the suction direction, and the exhaust air is blown out radially from the fan. The exhaust air hits the inner wall of the FFU case, changing its direction toward the rotation axis, and then flows into the filter. Therefore, the wind speed in the rotation axis direction just before entering the filter is low directly below the turbofan, i.e., near the rotation axis, and high in the axial direction away from the rotation axis. As described above, in conventional FFUs, variations in the air flow into the filter and the speed of the purified air blown out from the filter vary. Patent Document 1 aims to address this issue, but the punched plate significantly restricts the air flow, resulting in increased resistance in the flow path.

[0006] An object of the present invention is to provide a fan filter unit that suppresses variations in the wind speed of air discharged from a fan and uniforms the distribution of air flowing into the filter unit. Another object of the present invention is to provide a fan filter unit which improves the dust collection effect of the filter, thereby reducing the energy consumption of the motor and extending the life of the filter. [Means for solving the problem]

[0007] Representative features of the invention disclosed in this application are as follows. According to one aspect of the present invention, a fan filter unit (FFU) includes a turbofan that rotates the fan using a motor, a filter that cleans the air, and a case that houses the turbofan and the filter, the case having an air inlet for the fan and an outlet for air that has passed through the filter. In this FFU, a number of straightening vanes (hereinafter referred to as "straightening means") are arranged in the space between the turbofan and the filter, the vanes gradually decreasing in height from a position farther from the turbofan toward the turbofan. The turbofan is located inside the inlet, and the filter is positioned intersecting the rotational axis of the fan so as to block the outlet opening farther from the turbofan. The straightening means is formed by arranging a number of straightening vanes at predetermined intervals in the direction of the rotational axis in the space between the turbofan and the filter. The lengths of the straightening vanes in the direction of the rotational axis are longer at positions farther from the rotational axis and shorter at positions closer to the rotational axis.

[0008] According to another feature of the present invention, the case has a rectangular parallelepiped shape and includes a top wall and four side walls connected to the edges of the top wall. The bottom surface defined by the four side walls forms an exhaust opening, and a circular intake port is formed in the center of the top wall. The turbofan is disposed in the case so that the rotation axis passes through the intake port, and the fan exhausts the intake air below the top wall, radially outward from the rotation axis, toward the four side walls. The air, whose flow direction has been changed by the four side walls, is guided by the rectifying means before flowing into the filter. Each rectifying vane of the rectifying means is a thin rectangular plate extending in a direction parallel to the short sides of the case and the rotation axis. The length of the rectifying vanes in the rotation axis direction is gradually shortened, with the closest vane being the longest from the side wall forming the short sides and the furthest vane closest to the rotation axis being the shortest, or the length is gradually shortened for each successive vane. The upper ends of the respective flow straightening plates of the flow straightening means are fixed so as to be aligned in the horizontal direction. [Effects of the Invention]

[0009] According to the present invention, the distribution of airflow before flowing into the filter of the fan filter unit, particularly from the vicinity of the rotation axis to the distant portion, can be made more uniform than before, thereby improving the dust collection efficiency of the filter. Furthermore, a fan filter unit can be provided that suppresses variations in the wind speed of the clean air discharged from the filter. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a vertical cross-sectional view showing the overall structure of an FFU 1 according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a vertical cross-sectional view of the rectifying means 50 of FIG. 1. [Figure 3] FIG. 2 is a perspective view showing the appearance of the rectifying means 50 of FIG. [Figure 4] FIG. 3 is a vertical cross-sectional view showing a first modified example of the rectifying means 50 of FIG. 2. [Figure 5] FIG. 3 is a vertical cross-sectional view showing a second modified example of the rectifying means 50 of FIG. 2. [Figure 6] 2. FIG. 5 is a vertical cross-sectional view showing a third modified example of the rectifying means 50 of FIG. [Figure 7] 2. FIG. 6 is a vertical cross-sectional view showing a fourth modified example of the rectifying means 50 of FIG. [Figure 8] FIG. 10 is a vertical cross-sectional view showing the overall structure of an FFU 101 according to a second embodiment of the present invention. [Figure 9] FIG. 10 is a vertical cross-sectional view showing the mounting structure of a rectifying means 150A according to a modified example of the second embodiment of the present invention. [Figure 10] FIG. 10 is a perspective view showing the appearance of a rectifying means 250 according to a third embodiment of the present invention. [Figure 11] FIG. 10 is a perspective view showing the appearance of a rectifying means 350 according to a fourth embodiment of the present invention. [Figure 12] FIG. 10 is a vertical cross-sectional view showing the mounting structure of a rectifying means 350A according to a modified example of the fourth embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In each drawing, components having the same function are designated by the same reference numerals, and repeated explanations will be omitted. In addition, in this specification, the front, back, left, right, and up and down directions will be described as directions shown in the drawings. [Example]

[0012] 1 shows an FFU (fan filter unit) 1 according to a first embodiment of the present invention, and is a vertical cross-sectional view of the FFU 1. The FFU 1 has a case 30, inside which a turbofan 10, a filter 40, and rectifying means 50 are provided.

[0013] The FFU case 30 is a roughly rectangular parallelepiped housing having a top wall 31 and four side walls (32a to 32d; however, the right side wall 32c and the left side wall 32d are not visible in FIG. 1), and the bottom portion formed by the lower edges of the four side walls serves as an exhaust opening 33. An opening 31a that is circular when viewed from above (when viewed from the direction of the rotation axis A1) is formed in the center of the top wall 31. The opening 31a serves as an air intake port for drawing outside air from the outside of the FFU 1 into the internal space via the turbofan 10. The opening 31a should be located in the center of the top wall 31 in the front-to-rear direction and the center in the left-to-right direction. However, the opening 31a may also be positioned so as to be offset from the left-to-right center of the FFU case 30. The material of the case 30 can be selected arbitrarily, but it is preferable to manufacture the case 30 using sheet metal or pressed metal such as stainless steel.

[0014] The turbofan 10 includes a motor 20 having a rotating shaft 21 and a fan 15 attached near the upper end of the rotating shaft 21, and is disposed directly below the opening hole 31a. The turbofan 10 is unitized with the motor 20 and the fan 15 as a set, and has a housing (not shown) for fixing the motor 20. The housing (not shown) of the turbofan 10 is fixed with screws or the like to a mounting portion 34 formed near the opening 31a of the FFU case 30. The mounting portion 34 is formed by press working or the like so as to raise the periphery of the opening edge of the opening 31a upward. Four screw holes (not shown) for screwing the turbofan 10 are formed at four locations around the circumference of the mounting portion 34. Note that the method of attaching the turbofan 10 to the FFU case 30 is not limited to a method using screws (not shown), and any known fixing method can be used.

[0015] Turbofan 10 has rotating shaft 21 of motor 20 located concentrically with circular opening 31a in a top view and facing vertically, with the intake side of fan 10 facing opening 31a (upper side). Any type of fan 15 can be used for turbofan 10, but here, a so-called centrifugal fan is used, which draws air from opening 31a in the direction of arrow 25 and expels it radially from the side in the direction of arrow 26 by the centrifugal force of rotating fan 15. Air discharged from turbofan 10 in a direction perpendicular to rotation axis A1, as indicated by arrow 26, is discharged radially from the rotation axis A1 inside (below) top wall 31, reaching four side walls 32a to 32d (32c and 32d are not visible in FIG. 1). The air that is discharged radially in the direction of arrow 26 flows below the upper surface 31 of the FFU case 30 while rotating about the rotation axis A1, collides with the side walls of the FFU case 30 (front wall 32a, rear wall 32b, etc.) as indicated by arrow 27, and then changes direction and flows overall in a direction parallel to the rotation axis A1, i.e., downward, as indicated by arrow 28.

[0016] Almost the entire bottom surface of the FFU case 30 serves as the opening 33 through which the exhaust air from the filter 40 is discharged, and so no wall surface (bottom surface) is formed. The filter 40 is attached near the bottom end of the case 30 at a position separated by a predetermined distance in the direction of the axis A1 from the turbofan 10, and is disposed so as to cover the entire opening 33. For this reason, air inside the case 30 cannot flow out through the opening 33 unless it penetrates the filter 40. The method of fixing the filter 40 to the FFU case 30 is arbitrary, and can be the same fixing method as that used for known FFUs 1.

[0017] The filter 40 is, for example, a ULPA filter (Ultra Low Penetration Air Filter) specified by the Japanese Industrial Standards (JIS), and is used to purify the air by removing dust, dirt, and other particles from the air passing through. The type of filter 40 used in the present invention is not limited to a ULPA filter; other filters, such as a HEPA filter (High Efficiency Particulate Air Filter), may also be used. The air inflow direction of the filter 40 is parallel to the rotation axis A1 in FIG. 1 . In FIG. 1 , the air flows in from the top surface of the filter 40, passes through the interior of the filter 40, and the purified air is discharged downward as indicated by multiple arrows 29.

[0018] Considering the dust capture performance and durability of the filter 40, it is preferable that the air flow distribution be uniform over the entire upper surface of the filter 40. To achieve this uniform flow distribution, the air flow distribution is adjusted on the inlet side of the filter 40. In this embodiment, a rectifying means 50 is provided in the space between the filter 40 attached to the case 30 and the turbofan 10 to guide the air flow in a predetermined direction while keeping it uniform. A certain distance S1 is maintained between the lowermost position of the rectifying means 50 and the upper surface of the filter 40.

[0019] The rectifying means 50 is configured by arranging multiple rectifying plates (51, 71, etc.) extending vertically and is provided to uniform the flow of air entering each portion of the filter 40. The air flow paths between the multiple rectifying plates are parallel to the rotation axis A1, and the length of the flow path in the direction of the rotation axis A1 created by adjacent rectifying plates increases with distance from the central portion close to the rotation axis A1 in two radial directions (here, forward and rearward directions perpendicular to the surface of the rectifying plates). Therefore, the flow path created by the rectifying plates is short in the central portion, resulting in low resistance to the inflow of air. However, as the flow path becomes longer in the forward or rearward direction away from the central portion, resistance increases. As a result, the variation in air density on the discharge side (lower side) of the rectifying means 50 is smaller than the variation in air density on the inlet side (upper side) of the rectifying means 50. This results in a more uniform airflow entering the filter 40 than in a conventional example (a configuration without the rectifying means 50). In this way, by providing the rectifying means 50, the dust collection efficiency of the filter 40 is improved, and the durability of the filter 40 is also improved compared to the conventional filter.

[0020] The rectifying means 50 has an outer frame consisting of four side walls (described later in FIG. 3) for fixing a plurality of rectifying plates (51, 71, etc.), and thin metal plates (rectifying plates 51, 71, etc.) extending in the vertical and horizontal directions are arranged inside the outer frame. The rectifying plates 51 to 71 are arranged parallel to each other at regular intervals, and the heights (upper end positions) of the upper ends of the rectifying plates are the same, but the heights (lower end positions) of the lower ends of the rectifying plates are highest at the lower end position of plate 51 closest to a line passing through the rotational axis A1 of the motor 20, and the lower end positions of the rectifying plates are gradually lowered as they move away from the rotational axis A1 in the front-to-rear direction. The shape of the rectifying means 50 will be further described using FIGS. 2 and 3.

[0021] FIG. 2 is a detailed longitudinal cross-sectional view of the rectifying means 50 of FIG. 1. The rectifying means 50 comprises 41 thin metal rectifying plates 51-71 extending in the up-down, left-right, and right directions, arranged at equal intervals in the front-to-rear direction. While FIG. 1 schematically illustrates a reduced number of rectifying plates in the rectifying means 50, FIG. 2 illustrates all of the rectifying plates 51-71. However, because the rectifying plates 51-71 are numbered in order, the numerals 52-55, 57-60, and 62-69 are omitted. As can be seen from FIG. 2, the rectifying plates 51-71 are aligned so that their upper ends are positioned identically. The rectifying plate 51 located on the rotational axis A1 of the motor 20 has the shortest vertical length, and the lower ends of the rectifying plates 52-71 are gradually positioned lower as they move forward from the rotational axis A1. Similarly, the rectifying plates 52 to 71 are shaped so that the lower ends thereof are positioned lower in the rearward direction from the rotation axis A1. The lower edge of each of the rectifying plates 51 to 71 is horizontal when viewed in the left-right direction.

[0022] FIG. 3 is a perspective view showing the appearance of the rectifying means 50 of the first embodiment of the present invention, with (a) showing only the rectifying plates 51-71 (with the outer frames 72 and 73 omitted), and (b) showing the rectifying plates including the outer frames 72 and 73. As can be seen from FIG. 3(a), each of the rectifying plates 51-71 (reference numerals 52-60 and 62-70 are omitted in the figure) is a thin plate made of metal such as stainless steel, and extends in the vertical and horizontal directions. The rectifying plates 51-71 are aligned and evenly spaced. That is, the multiple rectifying plates 51-71 are fixed so as to be parallel to the short sides (front wall 31a, rear wall 31b) of the FFU case 30, which has a rectangular outer edge shape when viewed from above. For this fixation, connecting plates 72 and 73 are provided on both the left and right ends, as shown in FIG. 3(b). The connecting plates 72, 73 are arranged to be perpendicularly connected to the respective rectifying plates 51-71 and are relatively thick metal plates extending in the up-down and front-rear directions. The connecting plates 72, 73 and the respective rectifying plates 51-71 can be joined by any method, such as welding or adhesive bonding. The connecting plates 72, 73 may be made of metal or synthetic resin. In the rectifying means 50 shown in FIG. 3, the two rectifying plates 71 located at the front and rear ends also serve as the outer frame. Therefore, the two rectifying plates 71 may be made of synthetic resin and integrally formed with the connecting plates 72, 73. Furthermore, in addition to or instead of providing the connecting plates 72, 73 at the left and right ends, beam-shaped connecting members extending in the front-rear direction may be provided to fix the rectifying plates 51-71 so as to prevent them from moving.

[0023] Next, the operation of the FFU 1 will be described again with reference to Figure 1. When the motor 20 is started and the turbofan 10 begins to rotate, outside air is drawn in through the opening 31a and, due to the rotation of the fan 15, is discharged radially along the upper wall 31 in a direction perpendicular to the rotation axis A1 (radial direction) as indicated by arrows 26. The air flowing toward the front wall 32a and the rear wall 32d as indicated by arrows 26 hits the front wall 32a and the rear wall 32d, changing its flow direction to downward as indicated by arrow 27, and then the air flows downward as indicated by arrow 28 and enters the straightening means 50. Inside the FFU case 30 directly below the turbofan 10, the wind speed is higher at the outer portion of the FFU case 30 relative to the rotation axis A1, and the wind speed in the direction of the rotation axis is lower directly below the turbofan 10, i.e., at a position close to the rotation axis A1. In this embodiment, the rectifying means 50 is provided upstream of the filter 40 inside the FFU case 30, so that the air flow is adjusted by passing through the rectifying means 50 before flowing to the filter 40.

[0024] The upper end positions of the rectifying plates 51 to 71 of the rectifying means 50 are the same, but the lower end positions become lower from a position farther from the rotation axis A1 to a position closer to the rotation axis A1. Therefore, the frictional resistance of the air passing between the rectifying means 50 increases as the position becomes farther from the turbofan 10. With this structure, the wind speed flowing in the direction of arrow 28 inside the FFU case 30 is slowed down by the frictional resistance with the outer rectifying plates as the air moves to the outside. Also, the air directly below the turbofan 10, where the wind speed is low, is hardly slowed down by the inner rectifying plates, so that after passing through the rectifying means 50, the variation in wind speed is suppressed. This air with reduced variation enters the inlet surface (here, the upper surface) of the filter 40 and passes through the filter 40. Variation in the wind speed of the clean air 29 blown downward from the lower surface of the filter 40 is also reduced.

[0025] As described above, the FFU 1 of this embodiment is provided with a large number of rectifying plates 51-71 that guide airflow from the upper side to the lower side of the rectifying means 50. However, the number of rectifying plates 51-71 to be provided is arbitrary and is not limited to the total of 41 plates shown in FIG. 3 , and other numbers may be used. Furthermore, while the upper edge of the rectifying means 50 is arranged so that its upper edge is horizontal and its lower edge is oblique, this relationship may be reversed, so that the upper edge of the multiple rectifying plates 51-71 of the rectifying means 50 is oblique and the lower edge is horizontal. In this case, the rectifying means 50 shown in FIG. 3(b) may be attached to the FFU case 30 in an upside-down state. Furthermore, the upper and lower edges of the multiple rectifying plates 51-71 of the rectifying means 50 may each be oblique.

[0026] FIG. 4 is a longitudinal cross-sectional view showing a first modified example of the rectifying means 50 of FIG. 2. The rectifying means 50A of the first modified example is attached to the FFU case 30 in place of the rectifying means 50 shown in FIGS. 2 and 3. Like the rectifying means 50 shown in FIGS. 2 and 3, the rectifying means 50A is formed by arranging a large number of rectifying plates 57-71 in the front-to-rear direction at predetermined intervals so that they extend in the direction of the rotation axis A1. No other rectifying plates (corresponding to the rectifying plates 51-56 of FIG. 2) are provided between two rectifying plates 57. The length of the rotation axis A1 of the rectifying plates is long for the rectifying plates 71 on both sides (the front and rear ends) that are located farther from the rotation axis A1 when viewed in the front-to-rear direction, and the rectifying plates are formed so that the lower ends of the rectifying plates of the rectifying plates 70-57 are gradually positioned higher as they approach the rotation axis A1. That is, the height (length of rotation axis A1) of each of the rectifying plates 71 to 56 viewed individually decreases from 71 to 57. The size (width) in the left-right direction of the rectifying plates 71 to 57 is exactly the same as that of the rectifying plates 71 to 57 shown in Figure 3(a), and each of the rectifying plates 70 to 57 is a plate-like shape that extends in the up-down and left-right directions, and has a shape that has different heights but the same width.

[0027] In this way, in the first modified example, a predetermined portion (portion corresponding to depth D2) of the rectifying vane close to the rotation axis A1 is removed. The size of the front-to-rear length (depth) D2 of the removed portion can be determined arbitrarily, but the range of the rectifying vane to be removed should be the area directly below the fan 15, or at least the area projected downward in the direction of the rotation axis A1 of the fan 50 (the diameter D of the fan 15). f It is recommended to remove the rectifier plates (51 to 56 in Figure 2) that overlap with the fan 15 (the part included in f In the first modified example, by eliminating the plate immediately below the turbofan 10, the wind speed reduction caused by the rectifying means 50 is eliminated in the central portion of the filter 40, so that the variation in the wind speed of the clean air 29 (see FIG. 1) on the discharge side of the filter 40 can be suppressed.

[0028] 5A and 5B are diagrams showing a second modified example of the rectifying means 50 of FIG. 2, where (a) is a perspective view and (b) is a front view (view from the front) of the rectifying vane 68 of (a) alone. In the first embodiment, the height of the rectifying vanes 51 to 71 is constant depending on the left-right position, and the shape seen from the front is a long and narrow rectangle (rectangle). However, in the second modified example, as shown in FIG. 5B, the lower side of the part of width W2 near the center of the overall length W seen in the left-right direction is cut out in a rectangular shape. In other words, the vertical height h near the left end 68a and the right end 68b is 68 2 and 3, but the central portion 68c has a height h2 and is shaped like a long, thin strip. The size of the width W2 can be determined arbitrarily. For example, when the diameter D of the fan 15 is f It is advisable to set it appropriately in relation to W2>D. fThe other straightening vanes 51 to 67, 69 have a height h2 in the center, which is the same as the other straightening vanes, but the vertical heights near the left and right ends are different. Note that the straightening vanes 71 at the front and rear ends have no notches in the center, making them rectangular in shape when viewed from the front. By providing notches in this way in the center away from the right wall surface and left side surface of the FFU case 30, it is possible to suppress the deceleration of the wind speed by the straightening means 50 not only directly below the turbofan but also at locations away from the right wall surface or left side surface where the wind speed is low, thereby suppressing variations in the wind speed of the cleaned air 29.

[0029] FIG. 6 is a longitudinal cross-sectional view showing a third modified example of the current rectifier 50 shown in FIG. 2. The structure of the current rectifier 50C differs from that of the first embodiment. The individual shapes and required number of current rectifiers 51-71 used are the same as those of the current rectifier 50 shown in FIGS. 2 and 3. However, the current rectifiers 51-71 are arranged so that the spacing between them is not constant. That is, the spacing S2 between current rectifiers (e.g., current rectifiers 70 and 71) located farthest from the rotational axis A1 of the turbofan 10 is narrowest, and the spacing between adjacent current rectifiers gradually increases as the current approaches the rotational axis A1. The spacing S1 between the current rectifier 51 on the rotational axis A1 and the two current rectifiers 52 adjacent to it is widest. By gradually varying the spacing between the current rectifiers 51-71 in this manner, air friction resistance increases at positions farther from the rotational axis A1 of the turbofan 10, thereby enhancing the wind speed reduction effect. On the other hand, since the frictional resistance of the air is small at a position close to the rotation axis A1, the variation in the wind speed of the clean air flowing in at the upper surface of the filter 40 can be suppressed.

[0030] FIG. 7 is a vertical cross-sectional view showing a fourth modified example of the rectifying means 50 of FIG. 2. The shape and spacing of the rectifying means 50 are substantially the same as in Example 1, but the arrangement direction is different. Here, the upper edges of the rectifying plates 52 to 71 are arranged horizontally in the front-to-back and left-to-right directions, but the lower edges of the rectifying plates 52 to 71 are configured such that the closer they are to the rotation axis A1, as viewed from the right side (or left side), the higher they are, and the further they are from the rotation axis A1, the lower they are. The lower ends of the rectifying plates 52 to 71 are inclined toward the rotation axis A1. The angle θ1 formed by the rectifying plate 52 closest to the rotation axis A1 is smallest, and the angle θ2 formed by the rectifying plate 71 farthest from the rotation axis A1 is largest. In the example of FIG. 7, a rectifying plate (corresponding to 51 in FIG. 2) along the rotation axis A1 is not provided, but it may be provided. By tilting each of the straightening plates 52 to 72 in this manner, the wind speed is slowed down by the frictional resistance between the air and the straightening plates in areas away from the rotation axis A1 in the forward / backward direction, and the air is concentrated and sent to the area of ​​the filter 40 near the rotation axis A1 where the wind speed is low, thereby making it possible to uniformly distribute the air flowing in on the top surface of the filter 40. [Example]

[0031] Second Embodiment Fig. 8 is a vertical cross-sectional view showing the overall structure of an FFU 101 according to a second embodiment of the present invention. The structure of the FFU 101 is the same as that of a conventional FFU (fan filter unit), with a turbofan 10 and a filter 40 disposed inside an FFU case 130. The height H1 of the FFU case 130 is sufficiently smaller than the height H of the FFU 1 of this embodiment shown in Fig. 1, so there is no space inside the FFU case 130 to accommodate the rectifying means 150. Therefore, the rectifying means 150 is attached to the lower side of the FFU case 130, which corresponds to the exhaust side of the filter 40. The basic shape of the rectifying means 150 is formed based on the same concept as in the first embodiment, and in Fig. 8 it is configured to have rectifying plates 151 to 160 that have shapes similar to those of the rectifying means 50 in Figs. 2 and 3.

[0032] The length of the rectifying vane 151 in the direction of the rotation axis A1 of the motor 20 is shortest at the portion of the rectifying means 150 that coincides with (or is closest to) the rotation axis A1 of the motor 20, and the vertical length of the rectifying vane increases as the distance from the rotation axis A1 increases. The rectifying vanes 151-160 are arranged so that their upper ends are aligned on the same plane (horizontal plane), and the plane (imaginary plane) connecting their lower ends is oblique. Note that while FIG. 8 illustrates a state in which a total of 19 rectifying vanes 151-161 are arranged, the number of rectifying vanes 151-161 can be arbitrarily set depending on the outer shape of the case 130. When the rectifying means 150 is provided outside the case 130, the distribution of flow resistance (ease of airflow) on the exhaust side (lower side) of the filter 40 increases radially (horizontally) outward from the rotation axis A1.

[0033] As described above, in Example 2, the rectifying means 150 is arranged on the clean air blowing side of the filter 40, thereby suppressing variations in the speed of air passing through the filter 40. By arranging the rectifying means 150 on the clean air blowing side of the filter 40, the FFU case 130 can be formed to be as thin as conventional products; in other words, the present invention can be implemented by leaving the FFU 101 as is and simply adding the rectifying means 150 to it.

[0034] FIG. 9 is a diagram showing the mounting structure of a rectifying means 150A according to a modified example of the second embodiment of the present invention. The only difference from the configuration in FIG. 8 is the mounting structure of the rectifying means 150A; the rectifying effect is the same. The rectifying means 150 of the second embodiment shown in FIG. 8 is fixed to the FFU case 130 with screws or the like (not shown). In contrast, in this modified example, the rectifying means 150A is fixed by being suspended from mounting holes 201 formed in a mounting portion 200 such as a frame, for fixing the FFU 101A. The mounting holes 201 are slightly smaller than the FFU case 130, and have an opening with a substantially rectangular shape when viewed from above. The rectifying means 150A has multiple rectifying plates 151-160 arranged below the FFU case 130, extending downward toward the downwind side, i.e., in the direction of inflow of clean air. A flange portion 160B is formed on the upper side of the outer frame of the rectifying means 150A, bending it horizontally and extending radially outward from the upper edge of the outer frame.

[0035] Because the size of the outer edge of the flange portion 160B is larger than the opening of the mounting hole 201, the underside of the flange portion 160B abuts against the upper surface of the mounting portion 200 near the mounting hole 201, and the rectifying means 150A is maintained in a state where it does not fall downward from the mounting hole 201. Because the thickness of the flange portion 160B is sufficiently thin, the FFU case 130 can be fixed to the mounting portion 200 from above. In this way, the rectifying means 150A can be fixed by sandwiching the flange portion 160B between the upper surface of the mounting portion 200 and the FFU 101. Note that although the means for fixing the FFU case 130 to the mounting portion 200 is not shown in FIG. 9, known attachment means such as screws or bolts can be used. [Example]

[0036] FIG. 10 is a perspective view showing the appearance of a rectifier 250 according to a third embodiment of the present invention. While the first and second embodiments employ a number of flat rectifier plates 51-71, the third embodiment employs a number of cylindrical rectifier tubes 251-276 arranged concentrically with the rotation axis A1 of the turbofan 10. The rectifier 250 can be installed in place of the rectifier 50 shown in FIG. 1. Here, the rectifier tubes 251 to 262 are cylindrical, but the rectifier tubes 263-273 are not completely cylindrical because they abut the outer frame, and are shaped as if they have been cut at two circumferential locations (near the left and right ends). Furthermore, the rectifier tubes 275 and 276 are shaped such that only four partial circumferential locations remain. The rectifier tubes 251 to 276 are arranged so that their upper ends are on the same plane, but the height of the rectifier tubes 251 to 276 is preferably configured so that the rectifier tube 251 closest to the rotation axis A1 has the shortest tube length and the rectifier tube 276 farthest from the rotation axis A1 has the longest tube length.

[0037] Although not shown in FIG. 10 , a front wall (corresponding to 71 on the front side in FIG. 3 ) is formed on the front side of the rectifying means 250, a rear wall (corresponding to 71 on the rear side in FIG. 3 ) is formed on the rear side, a right wall (corresponding to 72 in FIG. 3 ) is formed on the right side, and a left wall (corresponding to 73 in FIG. 3 ) is formed on the left side. Beam-shaped connecting members 281 and 282 are provided to secure the rectifying plates 251 to 276. The connecting members 281 and 282 are members for fixing the rectifying plates 251 to 276 so that they do not move, and may be made of synthetic resin, metal, or other materials. By arranging the cylindrical rectifying tubes 251 to 276 concentrically with the rotation axis A1 in this manner, the flow of incoming air toward the filter 40 near the rotation axis A1 can be raised and the flow of incoming air toward the outer wall can be suppressed. This significantly improves the distribution of incoming air toward the filter 40 compared to a state in which the rectifying means 250 is not provided. [Example]

[0038] FIG. 11 is a perspective view showing the appearance of a rectifying means 350 according to a fourth embodiment of the present invention. The rectifying means 350 can be installed in place of the rectifying means 50 shown in FIG. 1. The rectifying means 350A has a front wall 370 formed on its front side, a rear wall 371 formed on its rear side, a right wall 372 formed on its right side, and a left wall 373 formed on its left side, which form side walls (370-373). A number of rectifying plates (374-377) extending inward perpendicularly to the wall surfaces are provided on the inner wall surfaces of each of these four side walls (370-373). Specifically, a number of rectifying plates 374 are connected to the entire rear side of the front wall 370, and a number of rectifying plates 375 are connected to the entire front side of the rear wall 371. A number of rectifying plates 366 are connected to the left side of the right wall 372, and a number of rectifying plates 367 are connected to the right side of the left wall 373. The multiple rectifying plates 374 have the same size, and similarly, the multiple rectifying plates 375, 376, and 377 each have the same size.

[0039] The frontmost straightening vane of straightening vane 376 is positioned slightly rearward so as not to come into contact with straightening vane 374, and the rearmost straightening vane is positioned slightly forward so as not to come into contact with straightening vane 375. Similarly, the frontmost straightening vane of straightening vane 377 is positioned slightly rearward so as not to come into contact with straightening vane 374, and the rearmost straightening vane is positioned slightly forward so as not to come into contact with straightening vane 375. In other words, the length of the straightening vanes 376 and 377 in the front-to-rear direction is D3, and D3 is shorter than the length obtained by subtracting the total front-to-rear length of 374, 375 from the front-to-rear length D of straightening means 350. The inward length (left-to-right length) of straightening vanes 376 and 377 is set to be less than 1 / 4 of the length of the short side of the rectangular outer frame as seen from the direction of rotation axis A1. In this way, by providing a large number of straightening plates 374-377 near where the air discharged radially outward from the turbofan 10 hits the wall surface (370-373) that forms the outer frame, the speed of the air flow in the direction of the rotation axis A1 that is introduced into the filter 40 can be weakened near the wall surface (370-373).

[0040] FIG. 12 is a vertical cross-sectional view showing the mounting structure of a rectifying means 350A according to a modification of the fourth embodiment of the present invention. The rectifying means 350 in FIG. 11 has a shape suitable for mounting to the FFU 1 in FIG. 1, while the rectifying means 350A in FIG. 12 has a shape suitable for mounting to the lower side of the case 130 of the FFU 101 in FIG. 8. The rectifying means 350A can be mounted in place of the rectifying means 150A shown in FIG. 9. The rectifying means 350A is mounted to the lower side, which corresponds to the exhaust side, of the filter 40. The inner shape of the outer frame (370, 371, etc.) of the rectifying means 350A, particularly the shapes of the rectifying plates 374, 375, etc., is substantially the same as that shown in FIG. 11. However, the inward protruding length L1 of the rectifying plates 374A, 375A is formed shorter than that of the rectifying plates 374, 375 shown in FIG. 11. Furthermore, a flange portion 378 is formed at the upper end position of the outer frame of the rectifying means 350A. The flange portion 378 is bent horizontally and extends radially outward from the upper edge of the outer frame. The size of the outer edge of the flange portion 378 is formed larger than the opening of the mounting hole 201 of the frame or the like, and the lower surface of the flange portion 378 abuts against the upper surface of the mounting portion 200 near the mounting hole 201, so that the rectifying means 350A does not fall downward from the mounting hole 201.

[0041] By providing the straightening means 350A outside the case 130 in this manner, the distribution of flow resistance (ease of flow of the clean air 190) on the exhaust side (lower side) of the filter 40 increases radially (horizontally) outward from the rotation axis A1, and the distribution of the air flowing into the filter 40 can be significantly improved compared to a state in which the straightening means 350A is not provided.

[0042] The present invention has been specifically described above based on several embodiments, but the present invention is not limited to the above-described embodiments and various modifications are possible without departing from the spirit of the present invention. For example, the shape of the rectifying plate may be elliptical or lattice-shaped. Furthermore, the rectifying means may be manufactured not only using a metal plate but also using synthetic resin or other materials. [Explanation of symbols]

[0043] 1 FFU (Fan Filter Unit) 10 turbofan 15 Fans 20 Motor 21 Rotation axis 25 Intake air (inflow air) 26, 27, 28 Wind Flow 30 FFU case 31 Upper Wall 31a Opening (inlet) 32 Side wall 32a Front wall 32b Rear wall 32c Right side wall 32d left side wall 33 Opening surface (discharge port) 34 Mounting part 40 filters 50, 50A~50D rectifier 51~71 Rectifier plate 72, 73 outer frame 101, 101A FFU 150, 150A, 250, 350, 350A rectification means

Claims

1. The air conditioner includes a turbofan that rotates and drives a fan using a motor, a filter that cleans the air, and a case that houses the turbofan and the filter, The case is a fan filter unit having an air intake port for the fan and an outlet port for the air that has passed through the filter, The turbofan is provided inside the suction port, the filter is disposed at a position intersecting a rotation axis of the fan so as to block the exhaust opening away from the turbofan, a rectifying means formed by arranging a number of rectifying plates at predetermined intervals so as to extend in the direction of the rotation axis, in a space between the turbofan and the filter; A fan filter unit characterized in that the length of the straightening plate in the direction of the rotation axis is longer at positions away from the rotation axis and shorter at positions closer to the rotation axis.

2. The case has a rectangular parallelepiped shape and has an upper wall and four side walls connected to the sides of the upper wall, and a bottom surface portion defined by lower sides of the four side walls serves as the discharge opening, The circular suction port is formed in the center of the upper wall, The turbofan is disposed such that the rotation axis passes through the suction port, and thereby the sucked air is discharged by the fan below the upper wall radially outward from the rotation axis toward the four side walls, 2. The fan filter unit according to claim 1, wherein the air whose flow direction has been changed by the four side walls is guided by the flow straightening means before flowing into the filter.

3. Each of the straightening plates of the straightening means is a rectangular thin plate extending in a direction parallel to the short side direction of the case and the direction of the rotation axis, The fan filter unit of claim 2, characterized in that the length of each straightening plate in the direction of the rotation axis is gradually shortened, with the straightening plate closest to the side wall forming the short side being the longest and the straightening plate farthest from the side wall forming the short side and closest to the rotation axis being the shortest, or the length of each straightening plate is shortened in stages for each of the multiple straightening plates.

4. 4. The fan filter unit according to claim 3, wherein the straightening means is fixed so that the upper end positions of the straightening plates are aligned horizontally or so that the lower end positions of the straightening plates are aligned horizontally.

5. The fan filter unit of claim 3, characterized in that the plurality of straightening plates are arranged in a row so that adjacent straightening plates are parallel to each other and parallel to the rotation axis, and are fixed by an outer frame or a beam-shaped connecting member that connects the plurality of straightening plates.

6. The fan filter unit according to claim 5, wherein none of the plurality of rectifying plates is arranged within a projected range in the direction of the rotation axis of the fan.

7. 4. The fan filter unit according to claim 3, wherein the straightening plates of the straightening means are disposed at an angle such that a lower end thereof is closer to the rotation axis than an upper end thereof.

8. The fan filter unit of claim 3, characterized in that the spacing between adjacent straightening plates of the straightening means is constant, or is configured so that the spacing between the straightening plates is narrow at a position far from the rotation axis and becomes wider as the position approaches the rotation axis.

9. The fan filter unit according to claim 2, characterized in that the straightening vanes are formed cylindrically, and a plurality of straightening vanes are arranged concentrically with the fan so that the central axis of each straightening vane coincides with the rotation axis.

10. The air conditioner includes a turbofan that rotates and drives a fan using a motor, a filter that cleans the air, and a case that houses the turbofan and the filter, The case has a rectangular parallelepiped shape, a top wall, and four side walls, and has an air inlet for the fan and an outlet for the air that has passed through the filter, and defines a space through which air flows from the fan to the filter. The turbofan is provided inside the suction port, the filter is disposed between the turbofan and the exhaust opening; A fan filter unit characterized in that a straightening means is provided on the clean air blowing side of the filter, which is formed by arranging a number of straightening plates at intervals, extending parallel to the rotation axis of the motor, so that the length in the direction of the rotation axis decreases as the distance approaches the rotation axis.

11. Each of the straightening plates of the straightening means is a rectangular thin plate extending in a direction parallel to the short side direction of the case and the direction of the rotation axis, The fan filter unit of claim 10, characterized in that the length of each straightening plate in the direction of the rotation axis is gradually shortened, with the straightening plate closest to the side wall forming the short side being the longest and the straightening plate farthest from the side wall forming the short side and closest to the rotation axis being the shortest, or the length of each straightening plate is shortened in stages for each of the multiple straightening plates.

12. the rectifying means is configured such that the plurality of rectifying plates are fixed by an outer frame that connects the plurality of rectifying plates so that the upper end positions of the plurality of rectifying plates are horizontally aligned, The fan filter unit according to claim 11, wherein the outer frame is fixed to the case.

13. The fan filter unit is fixed to an upper side of a mounting hole formed in an object to be mounted, a flange portion extending radially outward from an upper end edge of the outer frame; 13. The fan filter unit according to claim 12, wherein the flow straightening means is fixed in place by sandwiching the flange portion between the upper surface of the attachment object and the fan filter unit.

14. The air conditioner includes a turbofan that rotates and drives a fan using a motor, a filter that cleans the air, and a case that houses the turbofan and the filter, The case has a rectangular parallelepiped shape, a top wall, and four side walls, and has an air inlet for the fan and an outlet for the air that has passed through the filter, and defines a space through which air flows from the fan to the filter. The turbofan is provided inside the suction port, the filter is positioned adjacent to the exhaust opening at a location remote from the turbofan; a rectifying means having an outer frame in contact with the four side walls, the rectifying means having a plurality of rectifying plates projecting inward in directions perpendicular to each other, on each of the four side wall portions of the outer frame, in a space between the turbofan and the filter; A fan filter unit characterized in that each of the straightening plates of the straightening means is arranged so as to be parallel to adjacent straightening plates without contacting each other.

15. The lengths of the plurality of rectifying plates in the direction of the rotation axis of the fan are the same, 15. A fan filter unit as described in claim 14, wherein the inward protrusion width of the straightening vane is determined so that the straightening vane does not fall within the projection range of the fan as viewed in the direction of the rotation axis.

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