JP4391743B2 - Fan filter device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fan filter device that cleans and sends out air taken in from the outside by an electric fan and a filter provided in a case.
[0002]
[Prior art]
This type of fan filter device is used to clean the air in the assembly place and storage place of electronic equipment, precision machines and the like. For example, the fan filter device is installed so as to send out purified air from the upper side to the lower side of the assembly work table. Alternatively, a fan filter device is installed on the storage, and the purified air is sent out from the opening provided in the ceiling of the storage into the storage.
[0003]
FIG. 7 is a side view showing the structure of a typical conventional fan filter device. The fan filter device 100 includes an electric motor 102, a propeller fan 103 fixed to a rotating shaft in the vertical direction, and a filter 104 inside a rectangular parallelepiped or cylindrical case 101 so that these are arranged in the vertical direction. Is arranged.
[0004]
As indicated by the arrow line, the air taken in from the upper opening of the case 101 by the propeller fan 103 is sent downward, cleaned through the filter 104, and sent to the lower space.
[0005]
[Problems to be solved by the invention]
For example, as shown in FIG. 8, when the fan filter device 100 is mounted on the device or storage 110 (ceiling), the height H from the floor to the ceiling of the room is low, and the device or storage It may be difficult to ensure sufficient space above 110. In such a case, it is desirable that the height h of the fan filter device 100 is smaller (lower).
[0006]
However, in the fan filter device 100 having the above-described conventional structure, since the electric motor 102, the propeller fan 103, and the filter 104 are arranged in a substantially straight line in the vertical direction, it is difficult to reduce the height in the vertical direction. .
[0007]
Further, as schematically shown in FIG. 9, in the fan filter device 100 having the conventional structure, the wind speed 112 of the purified air that is sent to the lower space through the filter 104 decreases from the outer peripheral portion toward the central portion. In the center, there is an area where almost no air is sent out.
[0008]
This is because, due to the structure of the propeller fan 103, the wind speed is small at the center of the rotating shaft and the wind speed increases toward the outer periphery. As a result, the central portion of the filter 104 cannot sufficiently contribute to air purification. Further, vortices are likely to be generated due to the difference in wind speed between the peripheral part and the central part of the air sent out from the fan filter device 100. When the vortex is generated, there is a problem of winding up dust.
[0009]
The present invention has been made in view of the problems as described above, and it is possible to discharge purified air with a substantially uniform wind speed over the entire surface of a large-area filter while keeping the height low by using a plurality of fans. An object of the present invention is to provide a fan filter device. It is also an object of the present invention to prevent air swirl that tends to occur when a plurality of fans are used.
[0010]
[Means for Solving the Problems]
The fan filter device according to the present invention includes an electric fan and a filter in the case, and the air taken in from the outside by the electric fan passes through the filter from the upper surface side to the lower surface side and is then cleaned and provided on the case bottom surface. A fan filter device configured to be sent downward from a discharge port, wherein a plurality of centrifugal fans are provided as electric fans in a fan space provided with a partition wall beside the filter space in which the filter is accommodated. And connecting ducts that are juxtaposed with each other and connect the housing outlet of each centrifugal fan and the opening formed in the partition wall, and the air from each centrifugal fan passes through the coupling duct and the upper surface of the filter. It is configured to be sent out to the side space and from the fan space to the ceiling surface of the filter space Kunar as comprising such inclined portion is provided low, whereby the flow path cross-sectional area of the air on the upper surface side space of the filter is characterized by being configured to be smaller as the distance from the fan space.
[0011]
In this way, by arranging a plurality of centrifugal fans next to the filter and introducing air from the centrifugal fan to the upper surface side of the filter through the connecting duct, the fan filter device has a higher height than the conventional structure. It is possible to provide a fan filter device capable of meeting a demand for a large air volume while keeping the height low. In addition, since the cross-sectional area of the air flow path in the upper surface space of the filter becomes smaller as it gets farther from the fan space, the phenomenon of pressure drop on the side far from the fan space when the filter area is large is alleviated. Thus, a substantially uniform pressure distribution can be obtained over the entire upper surface of the filter. As a result, the wind speed distribution of the air sent downward from the outlet is substantially uniform.
[0012]
In a preferred embodiment, a horizontal rectifying plate that divides the flow of air sent from the housing outlet portion of the centrifugal fan through the opening of the partition wall in the vertical direction is provided on the side of the upper surface side space of the filter close to the fan space. The downstream tip of the horizontal rectifying plate is positioned at the approximate center of the upper surface space of the filter and is bent obliquely downward, so that the air sent to the lower side of the horizontal rectifying plate is upstream near the fan space. The air passes through the filter from the upper surface side to the lower surface side, and the air sent to the upper side of the horizontal rectifying plate passes through the filter from the upper surface side to the lower surface side on the downstream side far from the fan space.
[0013]
By such a function of the horizontal rectifying plate, the phenomenon that the pressure of the air sent into the upper surface side space of the filter decreases on the side far from the fan space is alleviated, and a substantially uniform pressure distribution is obtained over the entire upper surface of the filter. Become. As a result, the wind speed distribution of the air sent downward from the outlet is substantially uniform.
[0014]
More preferably, an upstream vertical rectifying plate for dividing the air flow in the horizontal direction is provided on the lower surface of the horizontal rectifying plate. Due to the action of the upstream vertical rectifying plate, it is possible to prevent the vortex from being generated in the air flow on the upstream side close to the fan space. When a vortex occurs in the air flow, the air pressure decreases at the center of the vortex, and a phenomenon occurs in which the wind speed of the air sent through the filter from this part becomes smaller than other parts. The occurrence of this phenomenon can be suppressed by the action of.
[0015]
In still another preferred embodiment, a downstream vertical rectifying plate that divides the air flow in the horizontal direction is provided on the ceiling surface of the filter space on the downstream side of the downstream end of the horizontal rectifying plate. Due to the action of the downstream vertical flow straightening plate, it is possible to prevent the vortex from being generated in the air flow on the downstream side far from the fan space. That is, similarly to the above-described upstream vertical rectifying plate, it is possible to suppress a phenomenon in which the wind speed of the air sent out from the filter due to the generation of vortices becomes uneven.
[0016]
Further, in another configuration of the fan filter device according to the present invention, an inclined portion is provided on the ceiling surface of the filter space so as to become lower as it is farther from the fan space. In addition to a configuration in which the area decreases as the distance from the fan space decreases, a plurality of connection ducts are juxtaposed at a predetermined distance in the horizontal direction, and the flow of air discharged from the plurality of connection ducts to the upper surface side space of the filter in the horizontal direction. A vertical rectifying plate for preventing swirling flow extending in the vertical direction is provided to prevent the swirling flow of air from occurring in the space on the upper surface side of the filter by dividing.
[0017]
According to such a configuration, the swirling flow preventing vertical rectifying plate is a swirling flow that is likely to be generated by the interaction of air discharged from the plurality of connecting ducts juxtaposed at a predetermined distance in the horizontal direction to the upper surface side space of the filter. Is effectively prevented by. As a result, a substantially uniform pressure distribution is obtained over the entire upper surface of the filter, and the wind speed distribution of the air sent downward from the discharge port becomes substantially uniform.
[0018]
In a preferred embodiment, two connecting ducts are provided for connecting the housing outlets of two centrifugal fans and the two openings formed in the partition wall, and two vertical rectifying plates for preventing swirl flow are provided. It is arranged in a substantially V shape in plan view so as to taper from the vicinity of the opening to the downstream side.
[0019]
According to such a configuration, in addition to the effect of preventing the swirling flow by the swirling flow preventing vertical rectifying plate, the air pressure is high inside the substantially V-shaped swirling flow preventing vertical rectifying plate in plan view. Therefore, the tendency for the pressure to decrease at the center of the upper surface side space of the filter is eliminated, and a more uniform pressure distribution can be obtained over the entire upper surface of the filter.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0021]
1A and 1B show the appearance of a fan filter device according to an embodiment of the present invention. FIG. 1A is a top view, FIG. 1B is a side view, and FIG. The fan filter device 10 includes an upper case 11 and a lower case 12 which are resin molded products. Three air intakes 13 are provided on one side in the longitudinal direction of the upper surface of the upper case 11. Further, a discharge port (blowing surface) 14 is provided on the bottom surface of the lower case 12. The discharge port 14 is formed from the side opposite to the one side in the longitudinal direction where the air intake port 13 is provided to the central portion in plan view.
[0022]
The air intake port 13 constitutes a first prefilter by a structure in which a plurality of slit openings formed in the upper case 11 are arranged and a nylon mesh (not shown) attached to the inside thereof. The first pre-filter of the air intake 13 prevents large dust such as hair and cotton dust from entering the inside of the fan filter device, thereby reducing the possibility of fan failure.
[0023]
2A and 2B are internal structural views of the fan filter device according to the embodiment of the present invention. FIG. 2A is a plan view, and FIG. 2B is a schematic side view of the internal structure. The substantially rectangular parallelepiped internal space of the fan filter device 10 is partitioned into a filter space 25 and a fan space 27 by a partition wall 26 in the vertical direction. A HEPA filter 18 and a second pre-filter 19 are disposed in the filter space 25, and two sets of sirocco fans (a type of centrifugal fan) 16 and an electric motor 17 that rotationally drives the Hspace filter 18 and a second pre-filter 19 are separated from each other by a predetermined distance. Are juxtaposed.
[0024]
Also, substantially rectangular openings 26a are formed at two locations of the partition wall 26, and connecting ducts 24 for connecting the outlet portions (housing outlet portions 16c) of the housings 16a of the respective sirocco fans 16 and the corresponding opening portions 26a are respectively provided. It has been. Instead of individually connecting the two sets of housing outlets 16c and the openings 26a with the two connecting ducts 24, only one opening is provided in the partition wall 26, and the opening and the two housing outlets 16c are provided. It is good also as a structure connected using one connection duct which branches into two forks.
[0025]
Air from each sirocco fan 16 passes through each connecting duct 24 and opening 26a as shown by arrows in FIGS. 2A and 2B, and the HEPA filter 18 and the second pre-filter in the filter space 25. It is sent out to the upper surface side space (filter upper space 25a) of the filter 19. A wind speed sensor 28 is attached to the inner wall of each connecting duct 24. As will be described later, the wind speed sensor 28 is a sensor for detecting the wind speed of the air sent from each sirocco fan 16, and may be provided on the inner wall of the housing outlet portion 16c of the sirocco fan 16.
[0026]
3A and 3B show the structure of the HEPA filter 18, wherein FIG. 3A is a plan view and FIG. 3B is a cross-sectional view seen from the side. The HEPA filter 18 is a main filter for cleaning air, and has a structure in which a filter body 22 formed by folding a glass fiber nonwoven fabric to form a large number of ridges is attached to an aluminum frame 21. By forming a large number of ridges, the surface area of the filter main body 22 that exerts the filtering action is increased.
[0027]
The second prefilter 19 is made of a nonwoven fabric and is attached to the upper surface (upstream side) of the HEPA filter 18. The second prefilter 19 can prevent the passage of dust of several microns such as mold spores and pollen. The second pre-filter 19 is obtained by cutting a non-woven fabric into a predetermined size, and is very inexpensive as compared with the HEPA filter 18. If clogging occurs, you can replace it with a new one. Alternatively, the filtering action can be easily recovered by detaching and washing with water or suction with a vacuum cleaner. Thereby, the lifetime of the expensive HEPA filter 18 can be extended.
[0028]
As can be seen from FIGS. 1 and 2, the air intakes (first pre-filters) 13 of the upper case 11 are formed so as to be positioned between the two sirocco fans 16 and at the three locations on both outer sides in plan view. ing. Air taken in from the outside through the air intake port (first pre-filter) 13 enters the housing 16a of the sirocco fan 16 from both sides of each sirocco fan 16, as indicated by the arrow line in FIG. It is led from the outlet 16c through the connecting duct 24 to the filter upper space 25a.
[0029]
FIG. 4 is a view showing the sirocco fan 16 and the electric motor 17 as viewed from the housing outlet 16c side of the sirocco fan 16. The sirocco fan 16 includes a substantially cylindrical housing 16 a and an impeller 16 b that rotates in the housing 16 a, and the rotating shaft of the impeller 16 b is connected to the rotating shaft 17 a of the electric motor 17. A rectangular housing outlet 16c is formed in the housing 16a. As indicated by the arrow lines, air is taken in from the air intake ports on both the left and right sides of the housing 16a, and the air is discharged from the housing outlet portion 16c (vertically in the front direction perpendicular to the paper surface).
[0030]
The air supplied to the filter upper space 25a in a state where a positive pressure is applied by each sirocco fan 16 passes through the second pre-filter 19 and the HEPA filter 18 from the upper surface side to the lower surface side, and is purified. 12 is sent out from the discharge port 14 on the bottom surface. At this time, unlike the structure illustrated in the description of the prior art, the fan filter device 10 of the present embodiment is not provided with an electric motor or the like that blocks the air flow above the HEPA filter 18. Air is sent in and air is efficiently cleaned.
[0031]
However, since air is sent from the fan space 27 provided beside the HEPA filter 18 to the upper space 25a of the HEPA filter 18, the pressure distribution in the filter upper space 25a tends to be non-uniform. That is, a phenomenon occurs in which the pressure on the side far from the fan space 27 is lower than the side closer to the fan space 27. In particular, in a large fan filter device in which the area of the HEPA filter 18 is increased in order to obtain a large air volume, the above tendency becomes strong.
[0032]
Therefore, an inclined portion 11a is provided on the ceiling surface of the filter upper space 25a, that is, the upper surface of the upper case 11, so as to become lower as the distance from the fan space 27 increases. 27 is configured to become smaller as the distance from the terminal 27 increases. By doing so, the phenomenon that the pressure on the side far from the fan space 27 becomes lower than the side near the fan space 27 is suppressed.
[0033]
Further, as shown in FIGS. 2A and 2B, a horizontal rectifying plate 29 that divides the flow of air sent from each sirocco fan 16 in the vertical direction on the side near the fan space 27 of the filter upper space 25a. Is provided. The downstream end portion 29a of the horizontal rectifying plate 29 is positioned substantially at the center of the filter upper space 25a and is bent obliquely downward as shown in FIG. 2 (b).
[0034]
Such a function of the horizontal rectifying plate 29 further suppresses a phenomenon in which the air pressure in the filter upper space 25 a becomes lower on the side farther from the fan space 27 than on the side closer to the fan space 27. That is, the air sent to the lower side of the horizontal rectifying plate 29 from each sirocco fan 16 passes through the second pre-filter 19 and the HEPA filter 18 from the upper surface side to the lower surface side on the upstream side near the fan space 27, and horizontally. The air sent to the upper side of the rectifying plate 29 passes through the second pre-filter 19 and the HEPA filter 18 from the upper surface side to the lower surface side on the downstream side far from the fan space 27.
[0035]
As described above, in the fan filter device 10 of the present embodiment, a substantially uniform air pressure is applied to the entire upper surface of the HEPA filter 18 by the action of the inclined portion 11a of the upper case 11 and the horizontal rectifying plate 29. As a result, the wind speed distribution of the air that has passed through the HEPA filter 18 becomes substantially uniform over the entire surface of the HEPA filter 18.
[0036]
In the fan filter device 10 of the present embodiment, the horizontal rectifying plate 29 is fixed to the four bosses 30 that are erected on the upper surface of the HEPA filter 18. However, various methods can be employed for this fixing method. For example, a boss for fixing the horizontal rectifying plate 29 may be formed on the inner wall of the lower case 12.
[0037]
Further, as shown in FIGS. 2A and 2B, vertical rectifying plates 31 and 32 for dividing the flow of air sent from each sirocco fan 16 in the horizontal direction are provided. That is, the upstream vertical rectifying plate 31 is provided so as to protrude downward from the lower surface of the horizontal rectifying plate 29, and the inner surface (filter space) of the upper case 11 on the downstream side of the downstream end portion 29a of the horizontal rectifying plate 29. The downstream vertical rectifying plate 32 is provided so as to protrude downward from the ceiling surface.
[0038]
For example, the upstream vertical rectifying plate 31 can be formed integrally with the horizontal rectifying plate 29 by resin molding. Similarly, the downstream vertical rectifying plate 32 can be formed integrally with the upper case 11. In this way, an increase in the number of parts can be suppressed, and the trouble of fixing the vertical rectifying plate 31 or 32 to the horizontal rectifying plate 29 or the upper case 11 can be saved. Of course, the vertical rectifying plate 31 or 32 may be made of a member different from the horizontal rectifying plate 29 or the upper case 11, or these members may be made of a material other than resin (for example, sheet metal).
[0039]
The upstream vertical rectifying plate 31 and the downstream vertical rectifying plate 32 have an effect of preventing the vortex from being generated in the air flow in the filter upper space 25a. When a vortex is generated in the air flow, the air pressure is lowered at the center of the vortex, and a phenomenon occurs in which the wind speed of the air sent from the center of the vortex through the HEPA filter 18 becomes smaller than the other portions.
[0040]
As shown in FIG. 2A, a pair of upstream vertical rectifying plates 31 are provided along the air flow sent out from the two sirocco fans 16. Similarly, a pair of downstream vertical rectifying plates 32 are provided. The pair of vertical rectifying plates 31 (or 32) has a shape in which the U-shaped plates face each other in plan view, and the space between the pair of vertical rectifying plates 31 (or 32) is the direction in which air flows. It is configured so as to gradually narrow after being spread along. By providing the vertical rectifying plates 31 and 32 having such a shape, the air flow in the filter upper space 25a becomes smooth and vortices are less likely to be generated. As a result, the air pressure applied to the upper surface of the HEPA filter 18 becomes uniform over the entire surface, and the wind speed distribution of the air that has passed through the HEPA filter 18 becomes substantially uniform over the entire surface of the HEPA filter 18.
[0041]
Next, an electronic circuit built in the fan filter device 10 will be described. The HEPA filter 18 having the above-described structure is clogged with dust when used for a long time. Although depending on the use environment, it is necessary to replace the HEPA filter 18 with a new one when a predetermined time has elapsed. Until the HEPA filter 18 is replaced, clogging gradually proceeds, and the pressure loss of the HEPA filter 18 gradually increases. If the pressure loss increases, the air volume of the air sent from the discharge port 14 decreases.
[0042]
In order to compensate for the decrease in the air volume as the usage time elapses as described above, the fan filter device 10 of the present embodiment uses the electric motor 17 (that is, the air volume of the sirocco fan 16) based on the output of the wind speed sensor 28 described above. ) Is provided with an electronic circuit for performing feedback control. In addition, this electronic circuit controls the two electric motors 17 so that the rotational speeds of the two sirocco fans 16 coincide.
[0043]
The wind speed sensor 28 provided on the inner wall of each connecting duct 24 detects the wind speed by utilizing the fact that the voltage between the base and emitter of the transistor varies with temperature. That is, as the wind speed of the air flow to which the wind speed sensor 28 is exposed increases, the cooling effect of the transistor increases. Therefore, if the base-emitter voltage is detected as the sensor output of the wind speed sensor 28, the wind speed can be determined. A wind speed sensor may be used in which an electrothermal element is used instead of the transistor and the change in the resistance value is a sensor output.
[0044]
Since the cross-sectional area of the connecting duct 24 (or the housing outlet portion 16c) to which the wind speed sensor 28 is attached is known, the air volume can be calculated if the wind speed is known. Although it is difficult to accurately measure the wind speed with the fan filter device having the structure shown in the description of the prior art, in the structure of this embodiment, the wind speed sensor 28 is attached to the flow path portion having a small flow path cross-sectional area. Therefore, it is possible to accurately detect a relatively fast wind speed.
[0045]
FIG. 5 is a block diagram of an electronic circuit 35 that performs feedback control of the electric motor 17 (sirocco fan 16) based on the output of the wind speed sensor 28. The output signals of the two wind speed sensors 28 provided on the inner wall of each connecting duct 24 are added by the adding circuit 36. The two sirocco fans 16 and the connecting duct 24 have the same dimensions, and a value corresponding to the sum of the air volumes by the two sirocco fans 16 is output from the adder circuit 36.
[0046]
The value corresponding to the total air volume output from the adding circuit 36 is compared with the air volume setting value by the comparator 37, and the rotation speed setting unit 38 sets the rotation speed of the electric motor 17 (sirocco fan 16) based on the comparison result. Set the value. This rotational speed setting value is given to the drive control circuit 40 (comparator 44) of each electric motor 17.
[0047]
Each motor drive control circuit 40 includes a motor driver 41, a control circuit 42, a rotation speed detection circuit 43, and a comparator 44. The rotation speed detection circuit 43 detects the rotation speed of the electric motor 17 (that is, the sirocco fan 16), and its output (rotation speed detection value) is input to the comparator 44. The comparator 44 compares the rotation speed setting value with the rotation speed detection value and gives a comparison result to the control circuit 42. The control circuit 42 makes the error between the rotation speed setting value and the rotation speed detection value zero. In addition, the electric motor 17 is controlled via the motor driver 41.
[0048]
As described above, the two electric motors 17 (sirocco fan 16) are maintained at a predetermined rotation speed (rotation speed setting value) by feedback control performed by each motor drive control circuit 40. The rotation speed setting value is set by the rotation speed setting unit 38 based on the comparison result between the sum of the detection values of the two wind speed sensors 28 and the air volume setting value. That is, a double feedback control loop is configured.
[0049]
By such control, the fan filter device 10 of the present embodiment can stably send out the purified air having the air volume set by the air volume setting value while rotating the two sirocco fans 16 at the same rotation speed. . If there is a difference between the rotation speeds of the two sirocco fans 16, a beat with a frequency corresponding to the difference between the rotation speeds will occur, causing noise.
[0050]
The output signals of the two wind speed sensors 28 are also input to the subtraction circuit 45. The subtraction circuit 45 obtains the difference between the output signals of the two wind speed sensors 28 and provides the output to the comparator 46. The comparator 46 compares the difference between the output signals of the two wind speed sensors 28 with a reference value (predetermined value), and gives the comparison result to the display 47 and the output circuit 48. With such a configuration, the fan filter device 10 according to the present embodiment can detect a failure in which the rotation shaft of the sirocco fan 16 and the rotation shaft of the electric motor 17 are disconnected.
[0051]
A case is assumed in which the rotation shaft of any one sirocco fan 16 and the rotation shaft of the electric motor 17 are disconnected. In this case, both of the two electric motors 17 are normally rotated, and no abnormality is detected only by the feedback signal from the rotation speed detection circuit 43, but there is a significant difference between the output signals of the two wind speed sensors 28. . When the difference between the output signals of the two wind speed sensors 28 is larger than the reference value, the fan filter device 10 according to the present embodiment determines that a failure has occurred and causes the display 47 to display that effect. Further, a signal indicating a failure is sent to the external device via the output circuit 48.
[0052]
The electronic circuit 35 configured as described above may be configured only by hardware, but most of the electronic circuit 35 can be configured as software (program) by using a microcomputer.
[0053]
The control of the electric motors 17 of the plurality of sirocco fans 16 by the electronic circuit 35 as described above can also be applied to a fan filter device having an internal structure as shown in FIG. In the fan filter device shown in the cross-sectional view of FIG. 6, two fan spaces 27 are provided so as to face both sides of the filter space 25, and each of the fan spaces 27 includes a centrifugal fan 16 and its electric motor. Multiple sets are arranged. The structure of this fan filter device has the disadvantage that the external dimensions of the fan filter device are increased by one to two fan spaces 27, but has the advantage that the weight balance is improved because the center of gravity is located at the approximate center. . Moreover, it can respond to the large sized fan filter apparatus using the HEPA filter 18 of a larger area.
[0054]
Next, another embodiment of the present invention will be described. FIG. 10 is a diagram illustrating an internal structure of a fan filter device for preventing a swirling flow according to another embodiment of the present invention. In the above-described embodiment, the horizontal rectifying plate 29 is provided as one of the means for making the air pressure in the filter upper space 25a as uniform as possible, and the upstream vertical rectifying plate 31 and the downstream vertical rectifying plate 32 are horizontally arranged. The rectifying plate 29 and the upper case 11 are provided. In this case, the upstream vertical rectifying plate 31 and the downstream vertical rectifying plate 32 have a function of making the pressure uniform by preventing the generation of local vortices of the air flow in the filter upper space 25a. In the configuration shown in FIG. 10, the horizontal rectifying plate 29 is not provided. Moreover, although the vertical baffle plate is provided, this is for preventing the swirl flow larger than a local vortex. Before describing the configuration of FIG. 10, a mechanism for generating a swirling flow will be described.
[0055]
FIG. 11 is a diagram illustrating how a swirling flow is generated in a fan filter device using a plurality of sirocco fans. Although exaggerated in this figure, when there is a difference in the strength of the airflow discharged from the upper and lower sirocco fans 16 through the individual connecting ducts 24 and from the individual openings 26a to the filter upper space 25a, the swirl flow TF Will occur. The illustrated swirl flow TF is an example in which the airflow discharged from the upper opening 26a is stronger than the airflow discharged from the lower opening 26a.
[0056]
Further, the swirl flow TF is also generated by the positional relationship between the upper and lower openings 26a. It is desirable that the upper and lower openings 26a be arranged at symmetrical positions with respect to the center (center line CL) of the partition wall 26 that divides the filter space 25 (filter upper space 25a) and the fan space 27. As shown in FIG. 11, they are arranged at positions shifted upward. An electric motor 17 is attached to the lower side of each sirocco fan 16 and is arranged in such a manner as to accommodate the two sirocco fans 16 and the electric motor 17 in a limited fan space 27.
[0057]
In FIG. 11, the difference in the strength of the air flow discharged from the upper and lower openings 26a to the filter upper space 25a is reduced by the control that makes the two electric motors 17 equal in number as described above. However, it is difficult to eliminate the asymmetry of the positional relationship between the upper and lower openings 26a due to limitations on the external dimensions of the fan filter device 10 and the dimensions of the sirocco fan 16 and the electric motor 17 accommodated therein.
[0058]
Therefore, the fan filter device 10 of the embodiment shown in FIG. 10 is provided with the vertical flow straightening plate 50 for preventing swirl flow extending in the vertical direction for preventing the swirl flow as described above. The vertical flow straightening plate 50 for preventing swirl flow is arranged in a substantially V shape in plan view so as to be tapered from the vicinity of the two openings 26a to the downstream side. The swirl flow preventing vertical rectifying plate 50 can be integrally formed on the ceiling surface (inside) of the upper case 11 by resin molding. Of course, the swirl flow preventing vertical rectifying plate 50 may be made of a member different from the upper case 11, or the swirling flow preventing vertical rectifying plate 50 may be made of a material other than resin (for example, sheet metal).
[0059]
As shown in FIG. 10 (a), the vertical rectifying plate 50 for preventing swirling flow that is substantially V-shaped in plan view is provided such that its center line CL1 coincides with the center lines of the two openings 26a. Yes. That is, the center line CL1 of the vertical rectifying plate 50 for preventing swirl flow is shifted from the center line CL (center line of the filter space 25) CL of the partition wall 26, and the shift direction and the shift amount are the shift directions of the two openings 26a. And the amount of deviation.
[0060]
The vertical flow straightening plate 50 for preventing swirl flow divides the air flow discharged from the two openings 26a into the filter upper space 25a in the horizontal direction (vertical direction in FIG. 10), respectively, and thereby from the two openings 26a. Prevents swirling flow due to interaction of exhaled air flow. Further, the air pressure in the inner region IA of the swirl flow preventing vertical rectifying plate 50 arranged in a substantially V shape in plan view is increased. Without such a swirl flow preventing vertical flow straightening plate 50, the pressure tends to decrease at the center of the filter upper space 25a. A uniform pressure distribution is easily obtained over the entire upper space 25a.
[0061]
If attention is paid only to the effect of preventing the swirling flow by dividing the air flow discharged from the two openings 26a into the filter upper space 25a in the horizontal direction, the swirling flow preventing vertical rectifying plate 50 is shown in FIG. You may provide as shown to (a) or (b). Any of the swirl flow preventing vertical rectifying plates 50 can obtain the above-described effect. Further, the swirling flow can be prevented (blocked) by the swirling flow preventing vertical straightening plate 50 as shown in FIG.
[0062]
FIG. 14 is a diagram illustrating an example of a state in which the wind speed sensor 28 is attached. (A) shows the state which provided the wind speed sensor 28 and the sensor baffle plate 60 in the side wall of the housing 16a (or connection duct 24) of the sirocco fan 16, (b) follows the BB line of (a). An enlarged section is shown. The wind speed sensor 28 includes two transistors 28a and 28b arranged at a predetermined interval on a substrate 28c. Small square holes are formed at predetermined intervals in the vertical direction on the side wall of the housing 16a (or the connecting duct 24), and the heads of the two transistors 28a and 28b of the wind speed sensor 28 are inserted into these square holes from the outside. Has been. The heads of the transistors 28a and 28b slightly protrude from the inner surface of the side wall of the housing 16a (or the connecting duct 24).
[0063]
The wind speed sensor 28 detects the wind speed by utilizing the fact that the voltage between the base and emitter of the transistor changes with temperature. One of the two transistors 28a and 28b of the wind speed sensor 28 is supplied with a larger amount of current than the other, and generates more heat. The higher the wind speed of the air flow to which the two transistors 28a and 28b are exposed, the higher the transistor cooling effect. Therefore, the wind speed can be determined by measuring the base-emitter voltage with the larger heat generation based on the base-emitter voltage of the transistor with the smaller heat generation.
[0064]
As shown in FIGS. 14 (a) and 14 (b), the sensor rectifier plate 60 provided between the two transistors 28a and 28b has a flow of air passing through the heads of the two transistors 28a and 28b. Smoothes the wind speed so that the wind speed can be detected correctly. Without the sensor rectifying plate 60, the air flow passing through the heads of the transistors 28a and 28b is likely to be disturbed due to clogging of the HEPA filter 18 or the like. When the turbulence of the air flow occurs, the wind speed sensor 28 cannot correctly detect the wind speed, and it becomes difficult to perform the feedback control based on the detection information of the wind speed sensor 28 as described above.
[0065]
14 (a) and 14 (b), even when the clogging of the HEPA filter 18 has progressed, the wind speed is correctly detected by the function of the sensor rectifier plate 60, and feedback control based on the wind speed (air volume) is performed. Can be done accurately. As shown in FIGS. 14A and 14B, the sensor rectifying plate 60 is a resin housing 16a (or connection) as a rib having a height of about 5 mm protruding from the inner surface of the side wall of the housing 16a (or connection duct 24). It can be formed integrally with the duct 24).
[0066]
As mentioned above, although embodiment of this invention was described with the modification, this invention is not restricted to said embodiment, It can implement with a various form. The description of the illustrated shape and structure and the material of each member is merely an example, and can be changed as necessary. For example, instead of a sirocco fan, another centrifugal fan (such as a turbo fan) may be used.
[0067]
Further, in the fan filter device of this embodiment, two centrifugal fans (and electric motors) are juxtaposed, but in order to realize a larger fan filter device, three or more sirocco fans and electric motors are arranged at predetermined intervals. They may be juxtaposed.
[0068]
【The invention's effect】
As described above, according to the fan filter device of the present invention, a plurality of centrifugal fans are arranged beside the filter, and air from the centrifugal fans is introduced to the upper surface side of the filter through the connection duct. As a result, the height of the fan filter device can be reduced as compared with the conventional structure. Further, by using a plurality of relatively small centrifugal fans, it is possible to meet a demand for a large air volume while keeping the height of the fan filter device low.
[Brief description of the drawings]
FIG. 1 is a diagram showing an external appearance of a fan filter device according to an embodiment of the present invention.
FIG. 2 is an internal structure diagram of a fan filter device according to an embodiment of the present invention.
FIG. 3 is a diagram showing the structure of a HEPA filter.
FIG. 4 is a diagram showing a sirocco fan and an electric motor as seen from the housing outlet side of the sirocco fan.
FIG. 5 is a block diagram of an electronic circuit that performs feedback control of an electric motor for a sirocco fan based on an output of a wind speed sensor.
FIG. 6 is a cross-sectional view showing the internal structure of another fan filter device.
FIG. 7 is a side view showing the structure of a conventional typical fan filter device.
FIG. 8 is a diagram illustrating a usage example of a fan filter device.
9 is a diagram schematically showing a wind speed distribution of air sent out from the fan filter device of FIG. 8. FIG.
FIG. 10 is a diagram showing an internal structure of a fan filter device for preventing a swirling flow according to another embodiment of the present invention.
FIG. 11 is a diagram illustrating a state in which a swirling flow is generated in a fan filter device using a plurality of sirocco fans.
FIG. 12 is a view showing a modification of the swirl flow preventing vertical rectifying plate for preventing swirl flow;
FIG. 13 is a view showing another modified example of the vertical flow straightening plate for preventing swirl flow for preventing swirl flow.
FIG. 14 is a diagram illustrating an example of an attachment state of a wind speed sensor.
[Explanation of symbols]
11 Upper case
11a Inclined part
12 Lower case
13 Air intake
14 Outlet (outlet surface)
16 Sirocco fan (centrifugal fan)
16a housing
16c Housing outlet
17 Electric motor
18 HEPA filter
24 Connecting duct
25 Filter space
25a Filter upper space
26 Bulkhead
26a opening
27 Fan space
28 Wind speed sensor
29 Horizontal rectifier
31 Upstream vertical straightening plate
32 Downstream vertical straightening plate
35 Electronic circuit
50 Vertical rectifier for swirling flow prevention

Claims (5)

An electric fan and a filter are provided in the case, and air taken in from the outside by the electric fan passes through the filter from the upper surface side to the lower surface side and is then purified, and then sent downward from an outlet provided on the bottom surface of the case. A fan filter device configured to be
A plurality of centrifugal fans as the electric fans are juxtaposed at a predetermined distance in a fan space provided with a partition wall beside the filter space in which the filter is accommodated, and a housing outlet portion of each centrifugal fan and the A connecting duct that connects an opening formed in the partition wall is provided, and air from each centrifugal fan is configured to be sent out to the upper surface side space of the filter through the connecting duct, and An inclined portion is provided on the ceiling surface of the filter space so as to become lower as the distance from the fan space decreases. ,
A horizontal rectifying plate that divides the flow of air fed from the housing outlet of the centrifugal fan through the opening of the partition wall in the vertical direction is provided on the side near the fan space of the upper surface side space of the filter, The downstream tip of the horizontal rectifying plate is positioned at the approximate center of the upper surface side space of the filter and is bent obliquely downward, so that the air sent to the lower side of the horizontal rectifying plate enters the fan space. Near the upstream side, the filter passes from the upper surface side to the lower surface side, and the air sent to the upper side of the horizontal rectifying plate passes the filter from the upper surface side to the lower surface side on the downstream side far from the fan space. It is comprised in the fan filter apparatus characterized by the above-mentioned. Wherein the lower surface of the horizontal rectifying plate, fan filter unit according to claim 1, wherein the upstream vertical rectifying plate for dividing the air flow in the horizontal direction is provided. In the downstream side of the downstream-side end portion of the horizontal rectifying plate, according to claim 1 or 2, characterized in that downstream vertical rectifying plates are provided for dividing the air flow in the horizontal direction on the ceiling surface of the filter space The fan filter device described. An electric fan and a filter are provided in the case, and air taken in from the outside by the electric fan passes through the filter from the upper surface side to the lower surface side and is then purified, and then sent downward from an outlet provided on the bottom surface of the case. A fan filter device configured to be
A plurality of centrifugal fans as the electric fans are juxtaposed at a predetermined distance in a fan space provided with a partition wall beside the filter space in which the filter is accommodated, and a housing outlet portion of each centrifugal fan and the A connecting duct that connects an opening formed in the partition wall is provided, and air from each centrifugal fan is configured to be sent out to the upper surface side space of the filter through the connecting duct, and An inclined portion is provided on the ceiling surface of the filter space so as to become lower as the distance from the fan space decreases. ,
In the upper surface side space of the filter, the plurality of connection ducts are juxtaposed at a predetermined distance in the horizontal direction, and the flow of air discharged from the plurality of connection ducts to the upper surface side space of the filter is divided in the horizontal direction. A fan filter device comprising a vertical flow straightening plate for preventing swirling flow extending in the vertical direction for preventing the swirling flow of air . Two connecting ducts are provided to connect the outlet portions of the housings of the two centrifugal fans and the two openings formed in the partition wall, and the vertical flow straightening plate for preventing swirl flow is the two openings. 5. The fan filter device according to claim 4 , wherein the fan filter device is arranged in a substantially V shape in plan view so as to be tapered from the vicinity to the downstream side.

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