JP2005163598A - Pipe fan - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To materialize a small size, low noise pipe fan capable of generating high air flow and static pressure with a little electric power consumption. <P>SOLUTION: Air on a room side is discharged to the outside from a front panel 3 through a bell mouth 5 of a body frame 4, through an impeller 6 having blades 9, and a side plate 7 and a main plate 8 of which diameters get larger as they get closer to a motor 13 side, and through a flow passage enclosed by a motor frame opening 18 of a motor frame 10 and a motor 13 wind tunnel pipe 2. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a structure of a pipe fan.

  In order to answer problems such as house chic in newly built houses, the Building Standards Act has been revised and so-called 24-hour ventilation is required to provide indoor air ventilation equipment. One of the facilities that realizes 24-hour ventilation is a pipe fan that is embedded in the wall and has the function of taking in air from the outside and exhausting it from the room.

  Because it is operated for 24 hours, it can be operated with low power consumption, noise that is difficult to notice even if it is operated at midnight, high ventilation (air flow), high static pressure that is not easily affected by outdoor wind Such requests are becoming stronger. In addition, since there is a possibility of being provided in each room, there is a strong demand for downsizing that the amount of protrusion on the indoor side is small and the fit is good.

  Conventionally, pipe fans have a structure in which a motor and a propeller fan or a turbo fan are housed in a main body frame. With propeller fans, the air volume can be increased, but it has the problem of low static pressure. In addition, in the case of using a turbo fan, the static pressure can be increased, but there is a problem that the air volume is difficult to obtain.

  Also, when using a motor and a propeller fan or turbo fan, if the distance between the front panel and the fan is short, wind noise will be generated or the flow will be bent sharply, resulting in increased flow turbulence and increased operating noise. Therefore, it is necessary to make the front panel protrude greatly to the indoor side.

  As a method for improving these, as disclosed in Patent Document 1, there is a method of driving an axial fan and a centrifugal fan coaxially. This is to suck air into the fan section with an axial flow fan and then boost the pressure with a centrifugal fan. Compared to the case of only an axial flow fan or a centrifugal fan, the P (pressure)-air volume (Q) characteristics are improved. Although it is said that it can be improved and the noise of air blow can be reduced, it requires a large dimension in the axial direction, which has a problem that the pipe fan becomes large.

  In addition, as shown in Patent Document 2, the motor is installed so that the axial direction of the motor is substantially perpendicular to the penetration direction of the wind tunnel pipe, and the fan is configured with a sirocco fan that supports high static pressure, and becomes a flow path. Some scrolls are placed in the body frame. With such a configuration, the advantage that the length of the pipe fan in the wind tunnel pipe can be shortened can be obtained. However, since the scroll cannot be increased, there is a problem that a large air volume cannot be obtained and noise is increased.

JP 9-32796 A

JP 2002-310093 A

  When trying to achieve high static pressure, large airflow, and low noise with such a pipe fan, the fan impeller performance should be improved, that is, with high airflow, high static pressure, and low noise while maintaining low input. In addition, there are problems such as reducing the fluid resistance due to the flow in the flow path provided before and after the impeller, and preventing the generation of noise due to the flow disturbance such as vortex. Furthermore, if the miniaturization is promoted, the flow path becomes narrow, and the fluid resistance tends to increase. Therefore, there is a problem that the fluid resistance must be reduced. Further, since dust floating in the room flows into the pipe fan together with air, there is a problem that they accumulate and prevent the operating characteristics from deteriorating when used for a long time.

  An object of the present invention is to provide a pipe fan having high static pressure that can be operated with less input, has low energy consumption, low noise, has a large ventilation volume (air volume), and is hardly affected by outdoor wind.

  The present invention relates to a pipe fan having air blowing means for sucking indoor air from an opening of a front panel or an opening formed by a front panel and a main body frame and exhausting the air to the outside through a wind tunnel pipe, from the space between the main body frame and the front panel. Air is introduced into the impeller consisting of a main plate, side plates and blades that increase in diameter toward the motor side through the bell mouth, and the motor directly connected to the impeller is supported by a motor support formed on the motor frame. The main feature is that the flow leaving the impeller is exhausted to the outside through a flow path formed between the wind tunnel pipe and the motor frame and a flow path formed by the motor frame and the motor.

  In addition, in the pipe fan arranged in the order of the front panel, main body frame, impeller, and motor from the indoor side to the outdoor side, the indoor air is sucked from the opening formed by the front panel and the main body frame, The air flows into the impeller having a flow path that increases in diameter as it goes to the outdoor side through the bell mouth, and the flow that exits the impeller is formed between the wind tunnel pipe and the motor frame. The exhaust gas is exhausted to the outside through a flow path formed by the motor frame and the motor.

  Further, the outer side of the front edge of the plurality of stays formed on the motor frame is formed obliquely from the front side to the rear side as viewed from the motor rotation direction, and the inner side of the rear edge of the stay is viewed from the motor rotation direction as the front side. It is characterized by being formed obliquely from the rear toward the rear side.

  Further, the number of blades of the impeller and the number of stays of the motor frame are in a prime number relationship.

  Further, a stationary blade is provided downstream of the impeller, and the number of blades of the impeller and the number of stationary blades are in a prime number relationship.

  Also, in a pipe fan with a front panel and a main body frame, the front panel entrance should be rounded, connected to a parallel part from there, and then tilted diagonally to allow for consideration between the front panel and the main body frame. Is characterized by gradually expanding.

  The pipe fan of the present invention is small in size, particularly has a small amount of protrusion to the indoor side, has a small size in the wall, has a large air volume, has a high static pressure, and is affected by the wind blown outdoors. It is difficult to achieve low noise that is difficult to notice even when driving at night.

  Small in size, especially with little protrusion to the indoor side, small size in the wall, large air flow, high static pressure, less affected by outdoor wind, etc. The purpose of obtaining a low-noise pipe fan that is less likely to be anxious is to provide air blowing means that sucks indoor air from the opening of the front panel or the opening formed by the front panel and the main body frame and exhausts it to the outside through the wind tunnel pipe In the pipe fan, the motor that is directly connected to the impeller by flowing air into the impeller composed of the main plate, side plate, and blades, whose diameter increases from the space of the main body frame and the front panel through the bell mouth to the motor side. , Supported by the motor support formed on the motor frame, and the flow out of the impeller is formed by the flow path formed between the wind tunnel pipe and the motor frame, the motor frame and the motor It was achieved by evacuating the outside via the by the channel.

  Embodiments of the present invention will be described below with reference to FIGS. FIG. 1 is a cross-sectional view of one embodiment of the apparatus of the present invention. FIG. 2 is a cross-sectional view of the pipe fan in which the pipe fan is taken out from the wind tunnel pipe. FIG. 3 is an external perspective view of the pipe fan. FIG. 4 is a plan view of the pipe fan as viewed from the back. FIG. 5 is a cross-sectional view of the motor frame, and FIG. 6 is a cross-sectional view showing another cross-sectional shape of the motor frame. FIG. 7 is an enlarged cross-sectional view of the opening formed by the front panel and the main body frame. FIG. 8 is a cross-sectional view when the impeller is cut along a plane including the shaft. FIG. 9 is a plan view when the impeller is viewed from the side plate side. FIG. 10 shows a cross section when the impeller is cut along the plane including the shaft, and is a cross-sectional view virtually depicting the blade when viewed along the blade surface. FIG. 11 is a schematic diagram showing the shape of the blade 9 near the parting line. 12 is a cross-sectional view of the motor frame 10 taken along the line AA shown in FIG. 13 is a cross-sectional view of the motor frame 10 AA shown in FIG. FIG. 14 is a plan view of the pipe fan as viewed from the front panel side. FIG. 15 is a plan view seen from the left side of 14. 16 is a plan view seen from the upper side of FIG. FIG. 17 is a plan view seen from the lower side of FIG. FIG. 18 is an exploded perspective view of the pipe fan.

  Reference numeral 1 denotes a building wall which communicates the interior and the exterior by passing a wind tunnel pipe 2 having an inner diameter of 100 mm or an inner diameter of 107 mm through the indoor side wall surface 1a and the outdoor side wall surface 1b. A front panel 3 is fixed to the main body frame 4. The front panel 3 is provided with openings 17a, 17b, and 17c in three directions, and serves as an air intake from the indoor side. The front panel 3 is detachably attached to the main body frame 4. The main body frame 4 is formed with a bell mouth 5 having a circular opening at the substantially center thereof and having an arc-shaped cross section.

  The motor frame 10 is hooked to the main body frame 4 by a fastening portion 27 after the hook portion 26 is hooked. The motor frame 10 has a substantially cylindrical shape on the side close to the main body frame 4, and is divided into three stays 21 from the middle, and a motor frame opening 18 is formed between the stays 21. A motor support portion 11 is formed on the side of the stay 21 opposite to the main body frame, and a motor flange 25 of the motor 13 is screwed thereto. A substantially annular motor band 14 is integrally formed on the motor support portion 11. A rotation shaft 15 protrudes from the motor 13 toward the main body frame 4, and a shaft fastening portion 16 of the impeller 6 is press-fitted and fixed to the rotation shaft 15.

  The impeller 6 includes a side plate 7, a main plate 8, and seven blades 9. The main plate 8 is formed with a cone portion 15 and has a shape that increases in diameter toward the motor 13 side. It looks like an S-shape. The side plate 7 is substantially parallel to the rotation shaft 15 on the main body frame 4 side, and has a shape that increases in diameter as it goes to the motor 13 side, like the main plate 8, and is substantially S-shaped when viewed in cross section. It has a shape. Thus, the impeller has a flow path whose diameter increases as it goes to the motor side.

  The blades 9 have a spiral shape, and the blades 9 are formed so as to have a larger diameter with respect to the rotation direction of the motor 13. The cross section of the blade 9 is formed so as to be substantially parallel to the rotation axis, and the outer diameter of the main plate 8 is smaller than the inner diameter of the side plate 7.

  The bell mouth 5 and the side plate 7 are partially overlapped with each other. The overlapping length in the axial direction is 1 mm, and the gap in the radial direction is 1 mm. This is to make the flow that flows outside the side plate 7 of the impeller 6 and enters the impeller 6 through the overlapping portion of the side plate 7 and the bell mouth 5, that is, the leakage flow as small as possible.

  The operation of the pipe fan will be described. When the motor is energized, the motor rotates and the impeller 6 rotates accordingly. By the action of the blades of the impeller 6, centrifugal force acts on the fluid to drive the air flow. Indoor air is sucked from the left and right three-way openings 17a, 17b, and 17c provided on the front panel 3 and flows to the bell mouth 5 through a flow path formed by the front panel 3 and the main body frame 4. . The flow is changed by about 90 degrees at the bell mouth 15 and then reaches the impeller 6. The flow leaving the impeller 6 flows outward in the right direction in the figure in the motor frame 10 and flows through the stationary blades 12 provided in the space between the motor frame 10 and the motor 13. At that time, a part of the air passes through the three motor frame openings 18 formed between the three stays 21, reaches the wind tunnel pipe 2, flows in the right direction in the figure, and passes through the stationary blade 12. After passing through the motor support 11, the flow mixes with the flow in the wind tunnel pipe 2, then passes through the wind tunnel pipe 2 and reaches the outdoors.

  FIG. 7 shows an enlarged cross-sectional shape of one opening provided in the front panel 3. The main body frame 4 is stopped so as to cover the front panel. The opening has a rectangular shape with rounded corners. Among the four opening edges around the opening, when the left direction in the figure is the front, the opening edge 76 on the front side is composed of a rounded portion 71, a flat portion 73, and a tapered portion 72 when viewed from the indoor side. The plane portion 78 is smoothly connected. Further, the other three opening edges form round portions on the indoor side. With this configuration, the flow of air from the indoor side flows into the opening 17a without peeling due to the roundness of the inlet, passes through the flow path 75 having a constant flow path width, and the area of the tapered portion 72 portion. The flow path 74 expands and enters the interior after decelerating, and can suppress flow separation at the inlet of the opening, turbulence, increase in speed due to contraction, etc., and reduce ventilation resistance In addition, the effect that the generated noise can be reduced can be obtained. Further, since the thickness of the opening edge 76 is slightly increased, the strength is increased and the deformation can be suppressed, so that the occurrence of the collision sound between the members generated by the vibration can be suppressed. If the amount of protrusion of the pipe fan into the room is reduced or the size of the front panel is reduced, the area of the opening is reduced, which is more effective for a small pipe fan. Moreover, the effect that dust hardly adheres to the wall surface on the flow path side of the front panel 3 is also obtained.

  Further, in this embodiment, the type in which the air is exhausted from the indoor side to the outdoors is shown, but even a type in which air is taken into the room from the outdoors can obtain an effect close to this. In this type, there is a pipe fan for intake with a fan inside, or a natural air inlet that is not inside the fan. In these cases, the air flow is reversed. The air that flows into the part surrounded by the front panel 3 and the main body frame 4 from the outside increases the speed due to the reduction of the area when it goes to the opening 17a, but there is no abrupt area change, so the turbulence is reduced and the fluid Resistance can be reduced, and increase in noise due to flow turbulence and vortex generation can be suppressed.

  The cross section of the stay 21 of the motor frame 10 has the shape shown in FIG. The stay 21 has an arc shape, and the shape of both ends thereof is as follows. An arrow 65 indicates the rotation direction of the motor, but the flow from the impeller flows to the exhaust side while turning in the same direction as the arrow. The front edge portion 61 of the stay 21 on the upstream side of the flow reaches the outer peripheral surface through the large curved surface portion 52 having a large radius of curvature following the tip portion 51 having a small radius of curvature, and the outside is It is diagonal. Further, the rear edge 62 on the downstream side of the flow reaches the outer periphery from the large curved surface portion 54 having a large curvature radius from the inside through the rear end portion 53 having a small curvature radius. Since the leading edge and the trailing edge have a shape along the flow in this way, the flow that flows outward while turning does not collide with the stay 21, so that there is no great disturbance and the fluid resistance Can be reduced. Further, when the flow collides with the stay 21, the influence on the impeller side and the generation of sinusoidal noise due to the interference with the impeller can be suppressed. In addition, an effect of preventing the dust from adhering to the stay 21 can be obtained.

  As shown in FIG. 6, in the front edge portion 61 of the stay 21, the same effect can be obtained even if the large curved surface portion 52 is a flat surface portion 55 and the inside and outside are constituted by a tip portion 57 having a small radius of curvature and a tangential portion 56. can get. In the rear edge portion 62, the same effect can be obtained even if the large curved surface portion 54 is formed as the flat surface portion 58 and the inside and outside are constituted by the tip portion 59 and the tangential portion 60 having a small radius of curvature.

  A section of the impeller 6 is shown in FIG. The left side is the upstream side of the flow. The main plate 8 has a substantially conical convex shape on the upstream side of the flow, has a shape that increases in diameter as it goes to the motor side, following the cone portion 22 whose diameter increases toward the downstream side, The cross section is S-shaped. Thereby, the flow in the axial direction is smoothly turned in the radial direction, and the flow at the outlet portion is directed slightly upward in the axial direction. Similarly, the side plate 7 also has a diameter that increases toward the right side in the drawing, and its cross section is substantially S-shaped. Thereby, the flow in the axial direction is smoothly turned in the radial direction, and the flow at the outlet portion is directed slightly upward in the axial direction. For this reason, since the flow can be smoothly directed in the axial direction and outward while utilizing the action of the centrifugal force, an effect that the air volume can be increased while the static pressure is high is obtained.

  The cross section of the blade 9 is parallel to the rotation axis like the blade 19 and is integrated with the main plate 8 in a certain part and the side plate 7 in a certain part. Further, since the outer diameter D2h of the main plate 8 is larger than the inner diameter D1s of the side plate 7 as shown in FIG. 10, it can be injection-molded using a plastic material such as ABS or polypropylene by moving the mold in the left-right direction in the figure. . For this reason, since it can be manufactured very easily and the whole is united, it is easy to balance and the amount of unbalance can be reduced.

  Moreover, even when dust adheres to the impeller, an effect that it is easy to clean with a brush or the like can be obtained.

  In such a molding method, since the mold is moved left and right, the parting line 101 in which the molds are in contact with each other is formed. A draft is necessary for die cutting, and the blade 9 has a step on the way. In such a case, as shown in FIG. 11, it is preferable to make the upstream blade 102 thicker than the downstream blade 103 and make the side plate 7 side have substantially the same thickness. When the flow passes through the parting line 101, the flow path area increases, and the downstream side becomes thicker and the flow path area is reduced. The effect is that resistance is low and generation of noise due to disturbance can be suppressed.

  The side plate 7 may be prepared as a separate body, and the main plate 8 and the blade 9 may be integrally molded and then combined. As a method of coupling, welding by ultrasonic waves or the like, adhesion by an adhesive, or the like can be used. In this case, since there is no parting line, the disturbance can be reduced. However, since the number of molds is increased by one and a process for bonding is required, the cost is increased. Further, even if the convex portion and the concave portion are formed and aligned, the roundness of the side plate 7 is difficult to be obtained, so the gap amount with the bell mouth 5 has to be increased, so that the loss due to leakage is reduced. May increase.

  The shape of the blade 9 of the impeller 6 will be described with reference to FIG. The blade inlet 91 is rounded, is formed to the inner peripheral portion 92 of the side plate 7 with a relatively small radius of curvature, and has an outwardly convex shape. The direction of rotation is clockwise in the figure, but the diameter of the blade 9 increases as it goes counterclockwise. The blades have a substantially linear shape in the back surface portion 94 from the inner peripheral portion 92 of the side plate 7 that hits the back surface of the side plate 7 to the outer peripheral portion 95 of the side plate 7. The angle θ1 of the blade at the inlet is preferably a shape along the flow. However, since the peripheral speed is small on the peripheral side, which is not the case with this blade, θ1 is made small. The exit angle θ2 is normally used from 20 degrees to 0 degrees. In the case of this blade, it is set to 45 degrees. In the case of a pipe fan, since a large amount of flow also flows outside the motor frame 10, the effect of static pressure recovery by the stationary blade 12 is small. Therefore, θ2 is slightly increased, the exit speed of the impeller is decreased, The flow loss that cannot be recovered as pressure can be reduced.

  Since the stationary blades 12 have three flanges 25 of the motor 13, three each are installed between them. The stationary blades 12 have a substantially arc shape, are provided radially outside the motor band 14, and are rounded at the tip. The inlet angle is preferably adjusted to the flow angle at the impeller outlet. In this case, the inlet angle is about 20 degrees, and the outlet angle is about 90 degrees (in a direction parallel to the rotation axis. In this way. Therefore, the flow coming out of the impeller 6 can be decelerated by the stationary blade 12 and recovered as static pressure, so that the fluid loss can be reduced.

  The total number of impellers 6, the stationary blades 12, and the motor support 11 is 12 and the number of impellers 6 is a prime number. If the number of impellers 6 and the number of stationary parts are the same or are in a multiple relationship, a sinusoidal noise of a harmonic component based on the frequency relationship between the number of impellers 6 and the number of rotations due to flow interference. So-called blade noise is likely to occur. Therefore, it is preferable that the number of both is in a prime number relationship as in this embodiment. Further, since the stay 10 is also divided into three parts, the number of blades 7 of the impeller 6 is also in a prime number relation to this, so that it is very difficult to generate impeller sound.

  The impeller 6 side of the motor band 14 has a slightly smaller diameter and has an arc shape in cross section, and is smoothly connected to the outlet of the main plate 8 of the impeller 6. It is hard to disturb the flow of the part. Further, since the stationary blade 12 does not cover the arc-shaped portion of the motor band 14, the motor frame 10 can be integrally formed in the left-right direction in FIG.

  As shown in FIG. 12, the motor frame 10 has a motor support portion 11 inside the stay 21. However, it is preferable to round the motor support portion 11 on the impeller 6 side because the flow is hardly disturbed. Furthermore, it is more preferable that the arrow 65 indicating the rotation direction of the motor is formed obliquely from the impeller 6 side toward the root. Since the occupation area of the motor support portion 11 with respect to the flow direction is reduced, the fluid resistance can be reduced.

  The wiring from the motor is bent at the portion of the stay 21 and placed along the stay 21 on the main body frame 4 side into the wiring housing portion 20, where it is connected to a connector (not shown), and then the terminal hole 24. Through and into the wall.

  A method of assembling a pipe fan according to the present invention will be described with reference to FIG. The motor 13 and the impeller 6 are press-fitted into the rotation shaft of the motor 13. If the shaft fastening portion 16 of the impeller 6 is notched and the outside thereof is tightened with a spring, the impeller 6 is difficult to come off. The motor 13 is put into the motor frame 10 from the left side in the drawing, and the motor flange and the motor support part are assembled by screwing. In this state, the motor frame 10 is screwed and fixed to the main body frame 4. In this state, the wiring from the motor 13 is passed through the wall side, and after the entire wiring is completed, the main body frame 4 is fixed to the wall, and the front panel 3 is attached to the main body frame 4. Thus, it can be easily constructed.

  Hereinafter, another embodiment of the present invention will be described with reference to FIG. FIG. 19 is an exploded perspective view of the pipe fan. The difference from FIG. 18 is that in the first embodiment, the bell mouth 5 is separated from the main body frame 4, and the main body frame and the motor frame are integrated into a main body frame.

  The motor 13 is put on the main body frame 4 from the right side in the figure, and the flange of the motor 13 and the motor support portion of the main body frame 4 are fixed by screwing. In this state, the impeller 6 is press-fitted into the rotating shaft of the motor 13. Thereafter, the bell mouth 5 is fixed to the main body frame 4. The front panel 3 is attached to the main body frame 4 after wiring and the like and after fixing the main body frame to the wall. This embodiment can be easily attached.

  The bell mouth 5 may be fixed to the main body frame 4 by turning or screwing. When the impeller 6 is fixed to the motor 13, the bell mouth 5 is a separate body, so that it can be assembled easily.

  Since it is small and can achieve high static pressure, large air volume, and low noise with low input, it is particularly suitable for a pipe fan with 24-hour ventilation.

It is sectional drawing of one Example of this invention apparatus. It is sectional drawing of the pipe fan which took out the pipe fan from the wind tunnel pipe. It is an external appearance perspective view of a pipe fan. It is the top view which looked at the pipe fan from the back. It is sectional drawing of a motor frame. It is sectional drawing which shows another cross-sectional shape of a motor frame. It is sectional drawing to which the part of the opening formed by a front panel and a main body frame was expanded. It is sectional drawing when an impeller is cut by the surface containing an axial center. It is a top view when an impeller is seen from the side plate side. It is sectional drawing which shows the cross section when an impeller is cut by the surface containing an axial center, and virtually showed the blade | wing when it sees along a blade surface. It is a model which shows the shape of the impeller 9 near the parting line. FIG. 3 is a cross-sectional view of the motor frame 10 taken along line AA shown in FIG. FIG. 3 is a cross-sectional view of the motor frame 10 taken along line AA shown in FIG. It is the top view seen from the front panel side of a pipe fan. It is the top view seen from the left side of FIG. It is the top view seen from the upper side of FIG. It is the top view seen from the lower side of FIG. It is a development perspective view of a pipe fan. It is a development perspective view of a pipe fan.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Wall, 2 ... Wind tunnel pipe, 3 ... Front panel, 4 ... Main body frame, 5 ... Bell mouth, 6 ... Impeller, 7 ... Side plate, 8 ... Main plate, 9 ... Blade, 10 ... Motor frame, 11 ... Motor support Part, 12 ... stationary blade, 13 ... motor, 14 ... motor band, 15 ... rotating shaft, 16 ... shaft fastening part, 17 ... opening, 18 ... motor frame opening, 21 ... stay, 22 ... cone part, 101 ... parting line.

Claims (6)

In a pipe fan having air blowing means for sucking indoor air from the opening of the front panel or the opening formed by the front panel and the main body frame and exhausting the air outside through the wind tunnel pipe,
A motor that is directly connected to the impeller is formed in the motor frame by allowing air to flow into the impeller consisting of the main plate, side plate, and blades that increase in diameter as it goes to the motor side from the space between the main body frame and the front panel. Supported by the motor support, and the flow exiting the impeller is exhausted to the outside through a flow path formed between the wind tunnel pipe and the motor frame and a flow path formed by the motor frame and the motor. A pipe fan characterized by that. From the indoor side to the outdoor side, in the pipe fan arranged in the order of the front panel, main body frame, impeller, motor,
The indoor air is sucked from the opening formed by the front panel and the main body frame, and the air flows through the bell mouth of the main body frame portion to the impeller having a flow path whose diameter increases as it goes to the outdoor side. A pipe fan characterized in that the flow exiting the air is exhausted to the outside through a flow path formed between the wind tunnel pipe and the motor frame and a flow path formed by the motor frame and the motor. In claim 1 or claim 2,
The outside of the front edge of the multiple stays formed on the motor frame is formed obliquely from the front side to the rear side as viewed from the motor rotation direction, and the inside of the rear edge of the stay is viewed from the front side as viewed from the motor rotation direction. A pipe fan characterized by being formed obliquely toward the side. In claim 1 or claim 2,
A pipe fan characterized in that the number of impeller blades and the number of stays in a motor frame are in a prime relationship. In claim 1 or claim 2,
A pipe fan having stationary blades downstream of an impeller, wherein the number of impeller blades and the number of stationary blades are in a prime number relationship. In a pipe fan with a front panel and body frame,
A pipe fan characterized in that the entrance of the front panel is rounded at the corner, connected to the parallel part from there, and then inclined obliquely so that the flow path between the front panel and the main body frame is gradually expanded. .

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