JP2022174300A - Serial axial flow fan - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a serial axial flow fan which can improve static pressure and wind volume with respect to input shaft power and can reduce noise.

SOLUTION: A serial axial flow fan 1 comprises a first axial flow fan 2 which blows out air sucked from an intake side from an exhaust side, and a second axial flow fan 3 connected to the first axial flow fan 2 along a center shaft of the first axial flow fan 2 and blowing out air sucked from the intake side from the exhaust side. An end part of the first axial flow fan 2 at the exhaust side and an end part of the second axial flow fan 3 at the intake side are connected to each other. A first impeller 21 comprises a plurality of first blades 211 extending radially outwardly and aligned in a circumferential direction. A second impeller comprises a plurality of second blades 311 extending radially outwardly and aligned in the circumferential direction. At least either of the first blades 211 and the second blades 311 comprise auxiliary blade parts 213.

SELECTED DRAWING: Figure 2

COPYRIGHT: (C)2023,JPO&INPIT

Description

The present invention relates to a serial axial fan in which axial fans are directly connected.

2. Description of the Related Art Conventionally, an axial fan has been used as a cooling fan for cooling electronic components arranged inside a housing of an electronic device. Both the static pressure and the air volume required for the cooling fan are increasing along with the increase in the amount of heat generated due to the high performance of the electronic components and the increase in the arrangement density of the electronic components due to the downsizing of the housing. In order to increase the static pressure and air volume of the cooling fan, a series-arranged axial fan has been proposed in which two (a plurality of) axial fans are connected in series in the axial direction, as described in Patent Document 1.

Japanese Patent Application Laid-Open No. 2007-303432

In recent years, the amount of heat generated from electronic components has increased, and the density of electronic components arranged inside a housing has increased. In addition, narrow gaps between components may be formed, or another electronic component may be placed behind another electronic component, making it difficult for the airflow from the series-arranged axial fan to reach the inside of the housing. . Poor airflow can result in inadequate cooling of electronic components.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a serial axial flow fan capable of improving static pressure and air volume relative to input shaft power and reducing noise.

An exemplary serial axial fan of the present invention includes a first axial fan for blowing air taken in from an intake side and blowing air from an exhaust side, and a first axial fan connected along the central axis of the first axial fan to take in air from the intake side. a second axial fan for blowing air from the exhaust side, wherein the end of the first axial fan on the exhaust side and the end of the second axial fan on the intake side are connected to each other. The first axial fan includes a first impeller that rotates around the central axis, a first motor unit that rotates the first impeller, and a first cylinder that surrounds the radially outer side of the first impeller. and a first support rib extending inward from the inner surface of the first tubular portion and supporting the first motor portion, wherein the first impeller extends radially outward and extends circumferentially. The second axial fan includes a plurality of first blades arranged in a direction, the second axial fan includes a second impeller rotating around the central axis, a second motor section rotating the second impeller, and the second a second housing including a second tubular portion surrounding the radially outer side of the impeller; and second support ribs extending inwardly from an inner surface of the second tubular portion and supporting the second motor portion, the second impeller comprising: comprises a plurality of second blades extending radially outward and arranged in the circumferential direction, wherein only the first blade out of the first blade and the second blade comprises an aileron portion, and the aileron portion is an in-line axial fan that curves toward the intake side as it goes radially outward.

According to the exemplary serial axial flow fan of the present invention, the static pressure and air volume relative to the input shaft power can be improved, and the noise can be reduced.

FIG. 1 is a perspective view of an example of a serial axial fan according to the present invention. FIG. 2 is a cross-sectional view of the serial axial fan shown in FIG. 1 taken along a plane including the central axis. FIG. 3 is a perspective view of the first axial fan viewed from above. FIG. 4 is a perspective view of the first axial fan viewed from below. 5 is an exploded perspective view of the first axial fan shown in FIG. 3. FIG. FIG. 6 is a cross-sectional view of the first axial fan shown in FIG. 3 taken along a plane including the central axis. FIG. 7 is a perspective view of the second axial fan as seen from above. FIG. 8 is a perspective view of the second axial fan as seen from below. 9 is an exploded perspective view of the second axial fan shown in FIG. 7. FIG. FIG. 10 is a cross-sectional view of the second axial fan shown in FIG. 7 taken along a plane including the central axis.

Exemplary embodiments of the invention are described in detail below with reference to the drawings. In this specification, in the series axial fan 1, the direction parallel to the central axis J1 of the series axial fan 1 is referred to as the "axial direction", and the direction orthogonal to the central axis J1 of the series axial fan 1 is referred to as "axial direction". A “radial direction” is defined as a “circumferential direction”, and a direction along an arc centered on the central axis J1 of the serial axial fan 1 is defined as a “circumferential direction”. Further, in the serial axial fan 1, the axial direction is the vertical direction, and the upper side IS and the lower side OS are defined with reference to the state shown in FIG. It should be noted that the vertical direction is a name used for explanation, and does not limit the positional relationship and direction in the state of use of the serial axial fan 1 .

<1. Schematic Configuration of Series Axial Fan> A series axial fan according to an exemplary embodiment of the present invention will be described below. FIG. 1 is a perspective view of an example of a serial axial fan according to the present invention. FIG. 2 is a cross-sectional view of the serial axial fan shown in FIG. 1 taken along a plane including the central axis. The serial axial fan 1 shown in FIGS. 1 and 2 sucks air from the end of the upper IS. The sucked air is then compressed and/or accelerated inside the serial axial fan 1 and discharged from the end of the lower OS. In the following description, the upper side may be referred to as the intake side, and the lower side may be referred to as the exhaust side.

As shown in FIGS. 1 and 2 , the serial axial fan 1 includes a first axial fan 2 and a second axial fan 3 . The first axial fan 2 is arranged above the second axial fan 3 . In other words, the first axial fan 2 is arranged on the intake side of the second axial fan 3 . In the serial axial fan 1, the first axial fan 2 and the second axial fan 3 are connected in series along the central axis J1. That is, the centers of both the first axial fan 2 and the second axial fan 3 coincide with the central axis J1.

The first axial fan 2 and the second axial fan 3 each have an upper side IS on the intake side and a lower side OS on the exhaust side. The exhaust side of the first axial fan 2 is connected to the intake side of the second axial fan 3 . That is, the air discharged from the first exhaust section 2302 provided on the end face of the lower side OS of the first axial fan 2 passes through the first outlet 2302 provided on the end face of the upper side IS of the second axial fan 3 . 2 Sucked from the suction part 3301 .

That is, the first axial fan 2 blows out the air sucked from the intake side from the exhaust side. The second axial fan 3 is connected along the central axis j1 of the first axial fan 2, and blows out the air sucked from the intake side from the exhaust side. The serial axial fan 1 connects the exhaust-side end of the first axial fan 2 and the intake-side end of the second axial fan 3 .

<2. Configuration of First Axial Fan 2> FIG. 3 is a perspective view of the first axial fan viewed from above. FIG. 4 is a perspective view of the first axial fan viewed from below. 5 is an exploded perspective view of the first axial fan shown in FIG. 3. FIG. FIG. 6 is a cross-sectional view of the first axial fan shown in FIG. 3 taken along a plane including the central axis. As shown in FIGS. 3 to 6, the first axial fan 2 includes a first impeller 21, a first motor section 22, a first housing 23, and a plurality of first support ribs 24. As shown in FIGS.

<2.1 Structure of First Housing 23 and First Support Rib 24> The first housing 23 is an exterior body of the first axial fan 2, and protects the first impeller 21, the first motor section 22, and the like.

The first housing 23 includes a first tubular portion 230 , a first intake flange portion 2311 and a first exhaust flange portion 2321 . The first tubular portion 230 is a tubular body penetrating from an upper end portion 231 to a lower end portion 232 along the central axis J1. An upper end portion 231 of the first tubular portion 230 is a first intake portion 2301 and a lower end portion 232 is a first exhaust portion 2302 . As shown in FIGS. 3 to 6, the first cylindrical portion 230 has four outer flat surfaces 236 formed by cutting the outer peripheral surface of the cylinder along a plane parallel to the central axis J1. The outer planes 236 are evenly spaced in the circumferential direction. The outer plane 236 is a plane parallel to the central axis J1.

In the first axial fan 2, the first impeller 21 rotates inside the first cylindrical portion 230 around the central axis J1 to generate an airflow. In other words, the first cylindrical portion 230 is a part of the exterior body and also a wind tunnel. That is, the first housing 23 includes a first tubular portion 230 that surrounds the radially outer side of the first impeller 21 . Also, the first impeller 21 rotates around the central axis J1.

A first intake flange portion 2311 is provided at the upper end portion 231 of the first housing 23 . The first intake flange portion 2311 has a square shape when viewed in the direction of the central axis J<b>1 , and the length of one side is longer than the inner diameter of the first cylinder portion 230 . A corner of the first intake flange portion 2311 when viewed in the direction of the central axis J<b>1 extends radially outward from the outer peripheral surface of the first tubular portion 230 . Here, the corner portion is a portion having a square corner portion and includes a region including the corner portion and having a constant width in the circumferential direction. Hereinafter, the corners are the same as the corners described above. In addition, the surfaces forming the sides of the square-shaped first intake flange portion 2311 when viewed in the direction of the central axis J<b>1 are flush with the outer plane 236 .

A first exhaust flange portion 2321 is provided at the lower end portion 232 of the first housing 23 . The first exhaust flange portion 2321 has a square shape when viewed in the direction of the central axis J<b>1 , and the length of one side is longer than the inner diameter of the first cylinder portion 230 . A corner portion of the first exhaust flange portion 2321 when viewed in the direction of the central axis J<b>1 extends radially outward from the outer peripheral surface of the first cylinder portion 230 . In addition, the surfaces forming the sides of the square-shaped first exhaust flange portion 2321 when viewed in the direction of the central axis J<b>1 are flush with the outer plane 236 . Furthermore, when viewed in the direction of the central axis J1, the first intake flange portion 2311 and the first exhaust flange portion 2321 overlap each other.

The first tubular portion 230 includes a first inner diameter portion 233 and a second inner diameter portion 234 . The first inner diameter portion 233 is arranged closer to the intake side than the second inner diameter portion 234, that is, on the upper side IS. The first inner diameter portion 233 is cylindrical, and the inner diameter D11 does not change in the axial direction. The minimum inner diameter of the first tubular portion 230 is the inner diameter D11. That is, the first inner diameter portion 233 is the minimum inner diameter portion. The second inner diameter portion 234 is arranged on the lower end portion 232 side of the first cylinder portion 230, that is, on the exhaust side end portion. The second inner diameter portion 234 has a larger diameter portion than the first inner diameter portion 233 . A portion radially overlapping the outer flat surface 236 of the second inner diameter portion 234 is an inner flat surface 2341 , and a portion connecting the inner flat surfaces 2341 in the circumferential direction is an inner curved surface 2342 . The lowermost side of the inner curved surface 2342 of the second inner diameter portion has an arc-shaped cross section taken along a plane perpendicular to the central axis, and has an inner diameter D12. The inner diameter D11 of the first inner diameter portion 233 is smaller than the inner diameter D12 of the inner curved surface 2342 of the second inner diameter portion 234 .

Inner curved surface 2342 includes conical portion 235 . The conical portion 235 is a portion of the inner surface of the conical shape that widens downward, ie, toward the exhaust side.

The first axial fan 2 has eleven first support ribs 24 . The eleven first support ribs 24 extend radially inward from the second inner diameter portion 234 and are arranged at regular intervals in the circumferential direction. The radially inner side of the first support rib 24 is connected to a base portion 2221 of the first motor portion 22, which will be described later. Thereby, the first motor section 22 is supported by the first housing 23 by the first support ribs 24 . The first housing 23, the first support ribs 24, and the base portion 2221 are resin moldings integrally formed of resin. In the first axial fan 2 , the first support ribs 24 are arranged on the lower end side of the first housing 23 . That is, the first support ribs 24 extend inward from the inner peripheral surface of the first cylindrical portion 230 and support the first motor portion 22 .

The first support rib 24 is arranged inside the first cylindrical portion 230 when viewed in the direction of the central axis J1. At least a portion of the airflow generated inside the first cylindrical portion 230 by the rotation of the first impeller 21 is traversed. The airflow generated by the rotation of the first impeller 21 has a velocity component in the axial direction and a velocity component in the direction in which the first impeller 21 rotates, that is, in the circumferential direction. Therefore, the first support rib 24 has a direction in which the airflow does not flow backward due to the velocity component of the airflow in the circumferential direction, that is, the first support rib 24 has an inclination in which the lower side is located downstream of the upper side IS in the rotational direction. Although details will be described later, when the first axial fan 2 and the second axial fan 3 are connected, the first supporting ribs 24 and the second supporting ribs 34 constitute stationary blades, and direct the airflow in the axial direction. rectify. That is, the first support ribs 24 support the first motor section 22 and also serve as stationary blades that rectify the airflow.

<2.2 Configuration of First Motor Section 22 > The first motor section 22 is of a so-called outer rotor type. As shown in FIG. 6 , the first motor section 22 includes a first rotor section 221 and a first stator section 222 . The first motor section 22 rotates the first impeller 21 .

<2.2.1 Configuration of First Stator Section 222 > The first stator section 222 includes a base portion 2221 , a bearing holding portion 2222 , an armature 2223 and a circuit board 2224 . The base portion 2221 is formed integrally with the first housing 23 and the first support ribs 24 . The base portion 2221 has a disk shape orthogonal to the central axis J1, and its center overlaps with the central axis J1. The bearing holding portion 2222 has a cylindrical shape, is arranged in the central portion of the base portion 2221, and extends toward the upper side IS. Note that the bearing holding portion 2222 may be formed integrally with the base portion 2221 . A ball bearing 2225 and a ball bearing 2226 are attached to the inner upper and lower portions of the bearing holding portion 2222 . A shaft 2213 , which will be described later, of the first rotor section 221 is rotatably supported via the ball bearings 2225 and 2226 . Note that the ball bearing 2225 and the ball bearing 2226 are examples of the bearing mechanism, and are not limited to this. A wide range of bearings having a structure capable of rotatably supporting the shaft 2213 can be employed.

The armature 2223 is fixed to the radially outer side of the bearing holding portion 2222 . Armature 2223 includes stator core 2227 , coil 2228 , and insulator 2229 . Stator core 2227 is a laminate in which electromagnetic steel sheets are laminated in the axial direction. Note that the stator core 2227 is not limited to a laminated body in which electromagnetic steel sheets are laminated, and may be a single member such as a sintered body of powder, a cast body, or the like.

Stator core 2227 has an annular core back and a plurality of (here, nine) teeth. Nine teeth are radially formed extending radially outward from the outer peripheral surface of the core back. Thereby, nine teeth are arranged in the circumferential direction. Coil 2228 is configured by winding a conductive wire around each tooth to which insulator 2229 is attached.

A bearing holding portion 2222 is press-fitted into the core back of the stator core 2227 , and the stator core 2227 is fixed to the bearing holding portion 2222 . The press-fitting may be a so-called interference fit, or a light press-fit, a so-called intermediate fit, in which the force due to the press-fit is weaker than that of the interference fit. Other methods such as adhesion may be used to fix the core back and the bearing holding portion 2222 . When the stator core 2227 is fixed to the bearing holding portion 2222, the center of the stator core 2227 overlaps with the central axis J1. In order to rotate the first motor portion 22 smoothly and efficiently, the nine teeth of the stator core 2227 are arranged at regular intervals in the circumferential direction.

A circuit board 2224 is attached to the base portion 2221 . Circuit board 2224 is electrically connected to coils 2228 of first stator section 222 . Circuit board 2224 contains the drive circuitry that drives coil 2228 .

The base portion 2221 of the first stator portion 222 is integrally formed with the first support ribs 24 . Thereby, the first stator portion 222 , that is, the first motor portion 22 is supported by the first support ribs 24 . Also, the first support rib 24 is integrally formed with the first housing 23 . Therefore, the first motor section 22 is connected to the first housing 23 via the first support ribs 24 , in other words, is supported by the first housing 23 .

<2.2.2 Configuration of First Rotor Section 221 > The first rotor section 221 includes a yoke 2211 , a field magnet 2212 , a shaft 2213 , and a shaft fixing member 2214 . The yoke 2211 is made of metal and has a lidded cylindrical shape centered on the central axis J1. A shaft fixing member 2214 is fixed to the center of the lid-shaped portion of the yoke 2211 . The shaft 2213 is fixed to the shaft fixing member 2214 by a fixing method such as press fitting. The fixing method is not limited to press fitting, and other methods such as adhesion may be used. That is, the yoke 2211 is fixed to the shaft 2213 via the shaft fixing member 2214 .

The field magnet 2212 has a cylindrical shape. Field magnet 2212 is fixed to the inner surface of yoke 2211 . The field magnet 2212 is alternately magnetized with N poles and S poles in the circumferential direction. Instead of the cylindrical field magnet 2212, a plurality of field magnets may be arranged in the circumferential direction.

The shaft 2213 is made of metal and has a cylindrical shape. The shaft 2213 is rotatably supported by the bearing holding portion 2222 , that is, the first stator portion 222 via ball bearings 2225 and 2226 . The center of the shaft 2213 rotatably supported by the bearing holding portion 2222 overlaps the central axis J1.

In the first motor section 22, the shaft 2213 is rotatably supported via the ball bearings 2225 and 2226, so that the first rotor section 221 is rotatable around the central axis J1 on the first stator section 222. supported by At this time, the radial inner surface of the field magnet 2212 of the first rotor portion 221 and the radial outer surface of the stator core 2227 face each other with a gap in the radial direction. Details of the operation of the first motor unit 22 will be described later.

<2.3 Configuration of First Impeller 21> As shown in FIGS. The cup 212 is cylindrical with a lid. Although the cup 212 has a lidded cylindrical shape, it is not limited to this, and the outer peripheral surface may have a different outer diameter in the axial direction, for example, a truncated cone shape.

The first wings 211 protrude radially outward from the radial outer surface of the cup 212 . Five first blades 211 are provided in the first impeller 21 . The five first blades 211 are arranged at regular intervals in the circumferential direction. That is, the first impeller 21 includes a plurality of first blades 211 extending radially outward and arranged in the circumferential direction. The first blades 211 are inclined in the circumferential direction, and the rotation of the first impeller 21 generates an air current flowing from the upper side to the lower side. In other words, the first wing 211 is inclined in a direction in which an airflow is generated downward from the upper IS. The surface on the exhaust side of the first blade 211, that is, the lower surface is the pressure surface. In addition, the surface of the first blade 211 on the intake side, that is, the surface of the upper IS is the suction surface.

The auxiliary blade portion 213 is provided on the radial outer edge portion of the first blade 211 . With this configuration, a vortex is generated in the aileron portion 213 , and the backflow of air in the gap between the radial outer edge portion of the aileron portion 213 and the inner surface of the first tubular portion 230 can be suppressed. Details will be described later. The auxiliary wing portion 213 is formed over the entire outer edge of the first wing 211 from the front end in the rotation direction to the rear end in the rotation direction. With this configuration, it is possible to obtain the effect of increasing the pressure by the auxiliary wing portion 213 over the entire outer edge portion of the first wing 211 . Thereby, the effect of increasing the pressure can be obtained. In addition, manufacturing may become easier than when the aileron 213 is formed on a part of the outer edge. Further, the aileron 213 is warped radially outward toward the axial upper side, that is, toward the intake side. By configuring in this way, it is possible to increase the pressure by the simply shaped aileron. In addition, it is easier to manufacture than a configuration in which an aileron is added and attached separately.

In the first axial fan 2 , the auxiliary blade portion 213 suppresses the inflow of air from the pressure surface side to the suction surface side at the radial outer edge portion of the first blade 211 . The details of the operation for suppressing the flow of air will be described later.

<2.4 Assembly and Operation of the First Axial Fan 2> As described above, the first stator portion 222 of the first motor portion 22 is supported by the base portion 2221 integrally formed with the first housing 23. It is assembled by attaching the part 2222, the armature 2223 and the circuit board 2224. That is, the first stator portion 222 is supported by the first housing 23 via the first support ribs 24 .

A yoke 2211 of the first rotor portion 221 is fixed inside the cup 212 of the first impeller 21 . The fixation of the yoke 2211 to the cup 212 may be performed by press-fitting or by adhesion. Moreover, it may be made by a fastening member such as a screw. The cup 212 is fixed to the yoke 2211 while suppressing displacement from the yoke 2211 . That is, the first impeller 21 is fixed to the first rotor portion 221 .

Then, the shaft 2213 of the first rotor portion 221 to which the first impeller 21 is fixed is fixed to the inner rings of the ball bearings 2225 and 2226 attached inside the bearing holding portion 2222 . The shaft 2213 is fixed to the inner rings of the ball bearings 2225 and 2226 by press-fitting, but is not limited to this. For example, a fixing method, such as adhesion or welding, which suppresses relative movement between the shaft 2213 and the inner ring and allows the shaft 2213 to rotate around the central axis J1 can be widely adopted. As described above, the first rotor portion 221 to which the first impeller 21 is attached is rotatably attached to the first stator portion 222 .

By attaching the first rotor portion 221 to the first stator portion 222 , the first impeller 21 is housed inside the first housing 23 . The radially outer side of the auxiliary blade portion 213 provided on the radially outer edge portion of the first blade 211 faces the inner surface of the first cylindrical portion 230 in the radial direction.

A current is supplied to the coil 2228 of the first motor section 22 with good timing from a drive circuit mounted on the circuit board 2224 . Thereby, the first rotor portion 221 of the first motor portion 22 is rotated in a predetermined direction. Here, the rotation direction of the first rotor portion 221 is the counterclockwise direction when the central axis J1 is viewed from the upper side IS.

As the first motor section 22 rotates around the central axis J1, the first impeller 21 fixed to the first rotor section 221 also rotates around the central axis J1. Due to the rotation of the first impeller 21 , an air current that flows in the axial direction while rotating in the circumferential direction is generated inside the first housing 23 , in other words, inside the first tubular portion 230 .

The rotation of the first impeller 21 pushes air against the first blade 211 . Therefore, the lower surface (exhaust side surface) of the first blade 211 is the pressure surface, and the upper IS surface (intake side surface) is the suction surface. The first impeller 21 has five first blades 211, and the inclination of the first blades 211 with respect to the central axis J1 is large. Therefore, the pressure difference between the pressure surface and the suction surface increases.

In the first axial fan 2 , the radially outer edge of the first blade 211 and the inner surface of the first tubular portion 230 are radially opposed to each other with a gap therebetween. Therefore, when the first impeller 21 rotates and a pressure difference occurs between the pressure surface and the suction surface of the first blade, the radial outer edge of the first blade 211 moves from the pressure surface side to the suction surface side. That is, an air flow is likely to occur from the lower side OS to the upper side IS.

Auxiliary blade portions 213 are provided on the radially outer edge portion of the first blade 211 . The aileron 213 is warped toward the upper IS (intake side). When the first impeller 21 rotates, the aileron 213 generates a vortex in the gap between the radially outer edge of the aileron 213 and the inner surface of the first cylindrical portion 230 . This vortex suppresses the air flow from the lower side to the upper side in the gap between the outer edge of the aileron 213 and the inner surface of the first tubular portion 230 . This suppresses the flow of air from the lower side to the upper side, thereby suppressing a decrease in the pressure difference between the pressure surface and the suction surface, that is, pressure loss. As a result, the first axial fan 2 can discharge high-pressure airflow from the first exhaust section 2302 .

A vortex is formed in the gap between the inner surface of the first cylindrical portion 230 and the radial outer edge of the aileron 213, and the vortex suppresses the air flowing back through the gap. In order to effectively suppress the air flowing back through the gap between the inner surface of the first cylindrical portion 230 and the radial outer edge of the aileron 213 due to the vortex, the inner surface of the first cylindrical portion 230 and the radial direction of the aileron 213 are It is preferable to make the gap with the outer edge of the as small as possible. Moreover, it is preferable that the gap between the inner surface of the first cylindrical portion 230 and the radial outer edge portion of the auxiliary wing portion 213 is uniform. Note that the uniform gap between the inner surface of the first cylinder portion 230 and the radially outer side of the auxiliary blade portion 213 means that the gap is not only precisely uniform, but also to the extent that the operation of the first axial fan 2 is not affected. It may include the case of variation. By configuring in this way, it is possible to suppress the gap from becoming large partially. As a result, partial changes in the gap are suppressed, the pressure balance is maintained, the first impeller 21 can rotate smoothly, and vibration, noise, and the like are suppressed. That is, the serial axial fan 1 can be made silent.

By making the gap between the inner surface of the first cylindrical portion 230 and the radially outer edge portion of the aileron portion 213 uniform, variations in the effect of suppressing backflow due to vortices are suppressed. As a result, the pressure balance in the circumferential direction of the first impeller 21 is less likely to collapse. As a result, the first impeller 21 can be smoothly rotated, and vibration and/or noise can be suppressed. That is, the serial axial fan 1 can be made silent.

The auxiliary wing portion 213 is accommodated within the axial length of the first tubular portion 230 . Since the auxiliary wing portion 213 surely faces the first cylindrical portion 230, the effect of increasing the pressure can be enhanced. In addition, since the auxiliary wing portion 213 is housed inside the cylinder, the shape of the auxiliary wing portion 213 that forms the same radial gap with the inner surface of the first cylindrical portion 230 is simplified. That makes it easier to manufacture the first impeller 21 . In addition, by making the surfaces of the auxiliary wing portions 213 that face each other in the radial direction cylindrical, changes in the outer diameter of the auxiliary wing portions 213 are reduced, and changes in pressure and flow velocity can be suppressed. As a result, it is possible to increase the effect of increasing the pressure of the discharged airflow.

In the first axial fan 2 , the radial outer edge of the auxiliary blade portion 213 preferably faces the inner surface of the first inner diameter portion 233 of the first cylindrical portion 230 in the radial direction. That is, it is preferable that at least a portion of the inner surface of the first cylindrical portion 230 that faces the aileron portion 213 in the radial direction is cylindrical. Since there is little change in the inner diameter of the portion of the first cylindrical portion 230 that faces the aileron 213, it is possible to increase the pressure with less variation in pressure and flow velocity.

Note that the auxiliary wing portion 213 may radially face the second inner diameter portion 234 . Also in this case, the shape of the outer edge of the aileron portion 213 is such that the gap between the radial outer edge of the aileron portion 213 and the inner surface of the second inner diameter portion 234, the radial outer edge of the aileron portion 213 and the first inner diameter It has a shape that is equal to the gap with the inner surface of the portion 233 . By configuring in this way, it is possible to obtain the above-described effect of suppressing vibration and/or noise. That is, the serial axial fan 1 can be made silent.

In addition, in the first impeller 21, the auxiliary blade portion 213 is formed over the entire area of the radial outer edge portion of the first blade 211 from the front end in the rotation direction to the rear end in the rotation direction. This reduces the pressure loss and increases the pressure of the airflow discharged from the first exhaust section 2302 . On the other hand, in some cases, the pressure of the airflow discharged from the first exhaust section 2302 may be a certain level. In such a case, the auxiliary blade portion 213 may be partially formed from the front end in the rotation direction to the rear end in the rotation direction of the radial outer edge of the first blade 211 . By doing so, it is possible to adjust the pressure of the airflow discharged from the first exhaust section 2302 . In addition, it is preferable that the portion forming the auxiliary blade portion 213 is formed in the same portion in the plurality of first blades 211 . By configuring in this way, the pressure distribution by the aileron 213 in each first blade 211 can be made the same or substantially the same, and the pressure acting on the first impeller 21 can be balanced. Thereby, vibration and/or noise can be suppressed. That is, the serial axial fan 1 can be made silent.

<3. Configuration of Second Axial Fan 3> FIG. 7 is a perspective view of the second axial fan viewed from above. FIG. 8 is a perspective view of the second axial fan as seen from below. 9 is an exploded perspective view of the second axial fan shown in FIG. 7. FIG. FIG. 10 is a cross-sectional view of the second axial fan shown in FIG. 7 taken along a plane including the central axis. As shown in FIGS. 7 to 10, the second axial fan 3 includes a second impeller 31, a second motor section 32, a second housing 33, and a plurality of second support ribs .

<3.1 Configuration of Second Housing 33 and Second Support Rib 34> The second housing 33 is an exterior body for the second axial fan 3 and the serial axial fan 1, and includes the second impeller 31 and the second motor. Protect the part 32 and the like.

The second housing 33 includes a second tubular portion 330 , a second intake flange portion 3311 and a second exhaust flange portion 3321 . The second tubular portion 330 is a tubular body penetrating from an upper end portion 331 to a lower end portion 332 along the central axis J1. An upper end portion 331 of the second tubular portion 330 is a second intake portion 3301 and a lower end portion 332 is a second exhaust portion 3302 . As shown in FIGS. 7 to 9, the second cylindrical portion 330 has four outer flat surfaces 336 formed by cutting the outer peripheral surface of the cylinder along a plane parallel to the central axis J1. The outer planes 336 are arranged at equal intervals in the circumferential direction. The outer plane 336 is a plane parallel to the central axis J1.

In the second axial fan 3, the second impeller 31 rotates around the central axis J1 inside the second tubular portion 330 to generate an airflow. In other words, the second cylindrical portion 330 is a part of the exterior body and also a wind tunnel. That is, the second housing 33 includes a second tubular portion 330 surrounding the radially outer side of the second impeller 31 . Also, the second impeller 31 rotates around the central axis J1.

A second intake flange portion 3311 is provided at the upper end portion 331 of the second housing 33 . The second intake flange portion 3311 has a square shape when viewed in the central axis J<b>1 direction, and the length of one side is longer than the inner diameter of the second cylindrical portion 330 . A corner portion of the second intake flange portion 3311 when viewed in the direction of the central axis J<b>1 extends radially outward from the outer peripheral surface of the second cylinder portion 330 . In addition, the surfaces forming the sides of the square-shaped second intake flange portion 3311 when viewed in the direction of the central axis J<b>1 are flush with the outer plane 336 .

A second exhaust flange portion 3321 is provided at the lower end portion 332 of the second housing 33 . The second exhaust flange portion 3321 has a square shape when viewed in the direction of the central axis J<b>1 , and the length of one side is longer than the inner diameter of the second cylinder portion 330 . A corner portion of the second exhaust flange portion 3321 when viewed in the direction of the central axis J<b>1 extends radially outward from the outer peripheral surface of the second cylindrical portion 330 . In addition, the surfaces forming the sides of the square-shaped second exhaust flange portion 3321 when viewed in the direction of the central axis J<b>1 are flush with the outer plane 336 . Furthermore, when viewed in the direction of the central axis J1, the second intake flange portion 3311 and the second exhaust flange portion 3321 overlap each other.

The second tubular portion 330 includes a first inner diameter portion 333 and a second inner diameter portion 334 . The first inner diameter portion 333 is arranged on the exhaust side of the second inner diameter portion 334, that is, on the lower side OS. The first inner diameter portion 333 is cylindrical, and the inner diameter D21 does not change in the axial direction. The minimum inner diameter of the second tubular portion 330 is the inner diameter D21. That is, the first inner diameter portion 333 is the minimum inner diameter portion. The second inner diameter portion 334 is arranged on the upper end portion 331 side of the second cylinder portion 330 , that is, on the intake side end portion. A portion radially overlapping the outer flat surface 336 of the second inner diameter portion 334 is an inner flat surface 3341 , and a portion connecting the inner flat surfaces 3341 in the circumferential direction is an inner curved surface 3342 . Inner curved surface 3342 includes conical portion 335 . The conical portion 335 is a portion of the inner surface of the conical shape and widens toward the upper side, ie, the intake side.

The uppermost side of the inner curved surface 3342 of the second inner diameter portion 334 has an arc-shaped cross section taken along a plane orthogonal to the central axis, and has an inner diameter D22. The inner diameter D21 of the first inner diameter portion 333 is smaller than the inner diameter D22 of the inner curved surface 3342 of the second inner diameter portion 334 .

Further, when connecting the first axial fan 2 and the second axial fan 3, the second inner diameter portion 234 of the first tubular portion 230 and the second inner diameter portion 334 of the second tubular portion 330 are continuous in the axial direction. connected as At this time, in order to smoothly connect the inner curved surface 2342 of the second inner diameter portion 234 of the first tubular portion 230 and the inner curved surface 3342 of the second inner diameter portion 334 of the second tubular portion 330, the inner diameter D12 and the inner diameter D22 are equal. . In order to smoothly connect the inner plane 2341 of the second inner diameter portion 234 of the first tubular portion 230 and the inner plane 3341 of the second inner diameter portion 334 of the second tubular portion 330, the inner diameter D11 and the inner diameter D21 are equal. .

In addition, in the axial lower end portion 332 of the second tubular portion 330, there is provided a region that overlaps the corner portion of the second exhaust flange portion 3321 in the radial direction, in other words, overlaps the inner curved surface 3342 of the second inner diameter portion 334 in the axial direction. The area is provided with an enlarged diameter portion 337 whose axial lower side is curved radially outward. The diameter-enlarged portion 337 gradually increases in inner diameter in the flow direction of the airflow. With such a shape, the airflow discharged from the second exhaust portion 3302 of the second tubular portion 330 is less likely to be disturbed. The enlarged diameter portion 337 has a curved surface when cut along a plane including the central axis J1. That is, the enlarged diameter portion 337 has a so-called bell mouth shape.

That is, the second housing 33 has a square-shaped second exhaust flange portion 3321 with one side larger than the inner diameter of the inner peripheral surface of the second tubular portion 330 at the exhaust side end portion. A portion radially overlapping the corner of the second exhaust flange portion 3321 at the exhaust side 332 end portion of the inner peripheral surface of the second cylindrical portion 330 curves radially outward toward the edge of the exhaust side 332 . Accordingly, by forming the enlarged diameter portion 337 into a shape that gradually expands, the airflow is less likely to be disturbed than in the case of a conical shape, and reduction in pressure and air volume can be suppressed.

The second axial fan 3 has eleven second support ribs 34 . The eleven second support ribs 34 extend radially inward from the second inner diameter portion 334 and are arranged at regular intervals in the circumferential direction. The radial inner side of the second support rib 34 is connected to a base portion 3221 of the second motor portion 32, which will be described later. Thereby, the second motor section 32 is supported by the second housing 33 by the second support ribs 34 . The second housing 33, the second support ribs 34, and the base portion 3221 are resin moldings integrally formed of resin. In the second axial fan 3 , the second support ribs 34 are arranged on the upper end portion 331 side of the second housing 33 . That is, the second support ribs 34 extend inward from the inner peripheral surface of the second cylindrical portion 330 and support the second motor portion 32 .

The second support rib 34 is arranged inside the second cylindrical portion 330 when viewed in the direction of the central axis J1. The second support ribs 34 are combined with the first support ribs 24 of the first axial fan 2 and used as stationary blades. Therefore, the second support ribs 34 are inclined in the same direction as the first support ribs 24 when the second axial fan 3 is connected to the lower side OS of the first axial fan 2 . That is, the axial lower side of the second support rib 34 is located on the rear side in the rotation direction of the first impeller 21 .

<3.2 Configuration of Second Motor Section 32> The second motor section 32 is of a so-called outer rotor type. As shown in FIG. 10 , the second motor section 32 includes a second rotor section 321 and a second stator section 322 . The second motor section 32 is configured to
Rotate the impeller 31 .

<3.2.1 Configuration of Second Stator Section 322 > The second stator section 322 includes a base portion 3221 , a bearing holding portion 3222 , an armature 3223 and a circuit board 3224 . The base portion 3221 is formed integrally with the second housing 33 and the second support ribs 34 . The base portion 3221 has a disk shape orthogonal to the central axis J1, and the center thereof overlaps with the central axis J1. The bearing holding portion 3222 has a cylindrical shape, is arranged in the central portion of the base portion 3221, and extends downward in the axial direction. Note that the bearing holding portion 3222 may be formed integrally with the base portion 3221 . A ball bearing 3225 and a ball bearing 3226 are attached to the inner upper and lower portions of the bearing holding portion 3222 . A shaft 3213 , which will be described later, of the second rotor portion 321 is rotatably supported via the ball bearings 3225 and 3226 . Note that the ball bearing 3225 and the ball bearing 3226 are examples of bearings, and are not limited to these. A wide range of bearings having a structure capable of rotatably supporting the shaft 3213 can be employed.

The armature 3223 is fixed radially outward of the bearing holding portion 3222 . Armature 3223 includes stator core 3227 , coil 3228 , and insulator 3229 . The stator core 3227 is a laminate obtained by laminating magnetic steel sheets in the axial direction. In addition, the stator core 3227 is not limited to a laminated body in which electromagnetic steel sheets are laminated, and may be a single member such as a sintered body of powder, a cast body, or the like.

Stator core 3227 has an annular core back and a plurality of (here, nine) teeth. Nine teeth are radially formed extending radially outward from the outer peripheral surface of the core back. Thereby, nine teeth are arranged in the circumferential direction. Coil 3228 is configured by winding a conductive wire around each tooth to which insulator 3229 is attached.

A bearing holding portion 3222 is press-fitted into the core back of the stator core 3227 , and the stator core 3227 is fixed to the bearing holding portion 3222 . The press-fitting may be a so-called interference fit, or a light press-fit, a so-called intermediate fit, in which the force due to the press-fit is weaker than that of the interference fit. Other methods such as adhesion may be used to fix the core back and the bearing holding portion 3222 . When the stator core 3227 is fixed to the bearing holding portion 3222, the center of the stator core 3227 overlaps the central axis J1. In order to rotate the second motor portion 32 smoothly and efficiently, the nine teeth of the stator core 3227 are arranged at regular intervals in the circumferential direction.

A circuit board 3224 is attached to the base portion 3221 . Circuit board 3224 is electrically connected to coils 3228 of second stator section 322 . Circuit board 3224 contains the drive circuitry that drives coil 3228 .

The base portion 3221 of the second stator portion 322 is integrally formed with the second support ribs 34 . Thereby, the second stator portion 322 , that is, the second motor portion 32 is supported by the second support ribs 34 . The second support ribs 34 and the second housing 33 are integrally formed. Therefore, the second motor section 32 is connected to the second housing 33 via the second support ribs 34 , in other words, is supported by the second housing 33 .

<3.2.2 Configuration of Second Rotor Section 321 > The second rotor section 321 includes a yoke 3211 , a field magnet 3212 , a shaft 3213 , and a shaft fixing member 3214 . The yoke 3211 is made of metal and has a lidded cylindrical shape centered on the central axis J1. A shaft fixing member 3214 is fixed to the center of the lid-shaped portion of the yoke 3211 . The shaft 3213 is fixed to the shaft fixing member 3214 by a fixing method such as press fitting. The fixing method is not limited to press fitting, and other methods such as adhesion may be used. Yoke 3211 is fixed to shaft 3213 via shaft fixing member 3214 .

The field magnet 3212 has a cylindrical shape. A field magnet 3212 is fixed to the inner surface of the yoke 3211 . The field magnet 3212 is alternately magnetized with N poles and S poles in the circumferential direction. Instead of the cylindrical field magnet 3212, a plurality of field magnets may be arranged in the circumferential direction.

The shaft 3213 is made of metal and has a cylindrical shape. The shaft 3213 is rotatably supported by the bearing holding portion 3222 , that is, the second stator portion 322 via ball bearings 3225 and 3226 . The center of the shaft 3213 rotatably supported by the bearing holding portion 3222 overlaps the central axis J1.

In the second motor section 32, the shaft 3213 is rotatably supported via the ball bearings 3225 and 3226, so that the second rotor section 321 is rotatable around the central axis J1 on the second stator section 322. supported by At this time, the radial inner surface of the field magnet 3212 of the second rotor portion 321 and the radial outer surface of the stator core 3227 face each other with a gap in the radial direction. Details of the operation of the second motor unit 32 will be described later.

<3.3 Configuration of Second Impeller 31 > As shown in FIGS. 9 and 10 , the second impeller 31 includes a plurality of second blades 311 and a cup 312 . The cup 312 is cylindrical with a lid. Although the cup 312 has a lidded cylindrical shape, it is not limited to this, and the outer peripheral surface may have a different outer diameter in the axial direction, for example, a truncated cone shape.

The second wings 311 protrude radially outward from the radial outer surface of the cup 312 . Seven second blades 311 are provided in the second impeller 31 . The seven second wings 311 are arranged at regular intervals in the circumferential direction. That is, the second impeller 31 includes a plurality of second blades 311 extending radially outward and arranged in the circumferential direction. The second blade 311 is inclined in the circumferential direction, and the rotation of the second impeller 31 generates an airflow directed from the upper side IS to the lower side OS. In other words, the second wing 311 is inclined in a direction to generate an airflow from the upper side IS to the lower side OS.

<3.4 Assembly and Operation of Second Axial Fan 3> As described above, the second stator portion 322 of the second motor portion 32 is supported by the base portion 3221 integrally formed with the second housing 33. It is assembled by attaching the part 3222, the armature 3223 and the circuit board 3224. That is, the second stator portion 322 is supported by the second housing 33 via the second support ribs 34 .

A yoke 3211 of the second rotor portion 321 is fixed inside the cup 312 of the second impeller 31 . The fixation of the yoke 3211 to the cup 312 may be performed by press-fitting or by adhesion. Moreover, it may be made by a fastening member such as a screw. The cup 312 is fixed to the yoke 3211 while suppressing displacement from the yoke 3211 . That is, the second impeller 31 is fixed to the second rotor portion 321 .

Then, the shaft 3213 of the second rotor portion 321 to which the second impeller 31 is fixed is fixed to the inner rings of the ball bearings 3225 and 3226 attached inside the bearing holding portion 3222 . The fixing of the shaft 3213 to the inner rings of the ball bearings 3225 and 3226 is performed by press-fitting, but is not limited to this. For example, a fixing method, such as adhesion or welding, which suppresses relative movement between the shaft 3213 and the inner ring and allows the shaft 3213 to rotate around the central axis J1 can be widely adopted. As described above, the second rotor portion 321 to which the second impeller 31 is attached is rotatably attached to the second stator portion 322 .

By attaching the second rotor portion 321 to the second stator portion 322 , the second impeller 31 is housed inside the second housing 33 . The radially outer side of the second blade 311 radially faces the inner surface of the second tubular portion 330 . Also, the second blade 311 is accommodated inside the axial length of the second cylindrical portion 330 . Also, the radial gap between the inner surface of the second cylindrical portion 330 and the radially outer side of the second blade 311 is uniform. It should be noted that the uniform gap between the inner surface of the second cylindrical portion 330 and the radially outer side of the second blade 311 means that the gap between the inner surface of the second cylindrical portion 330 and the radially outer side of the second blade 311 is uniform not only when it is accurately uniform, but also to such an extent that the operation of the second axial fan 3 is not affected. Including cases where there is variation.

A current is supplied to the coil 3228 of the second motor section 32 with good timing from the drive circuit mounted on the circuit board 3224 . Thereby, the second rotor portion 321 of the second motor portion 32 is rotated in a predetermined direction. Here, the rotation direction of the second rotor portion 321 is the counterclockwise direction when the central axis J1 is viewed from the upper side IS.

As the second motor portion 32 rotates around the central axis J1, the second impeller 31 fixed to the second rotor portion 321 also rotates around the central axis J1. Due to the rotation of the second impeller 31 , an air current that flows in the axial direction while rotating in the circumferential direction is generated inside the second housing 33 , in other words, inside the second tubular portion 330 .

<4. Details of Series Axial Fan 1> Compared to the first blades 211 of the first axial fan 2, the second blades 311 of the second axial fan 3 are less inclined with respect to the axis, and the pressure surface and the suction surface are separated from each other. pressure difference is small. Therefore, pressure loss can be suppressed without providing an auxiliary wing portion on the radial outer edge portion of the second blade 311 . In addition, with such an impeller having blades that are less inclined with respect to the axis, it is easier to obtain the effect of increasing the flow velocity rather than the effect of compressing the air by rotation. That is, the second axial fan 3 has a higher ability to increase the discharge flow rate than the first axial fan 2 . In other words, the first axial fan 2 has a higher ability to increase the discharge pressure than the second axial fan 3 does. In the serial axial fan 1, the pressure and flow rate are increased by connecting these axial fans with different capacities in series. Details of the serial axial fan 1 will be described below.

A serial axial fan 1 is formed by connecting a first axial fan 2 and a second axial fan 3 in series in the axial direction. The lower end of the first axial fan 2 and the upper end of the second axial fan 3 are connected. The first exhaust flange portion 2321 of the first axial fan 2 and the second intake flange portion 3311 of the second axial fan 3 are in axial contact and fixed. Fixing of the first exhaust flange portion 2321 and the second intake flange portion 3311 can be done by screwing, but is not limited to this. For example, adhesion etc. can be mentioned. The first exhaust portion 2302 of the first axial fan 2 and the second intake portion 3301 of the second axial fan 3 are connected without any gap. This prevents the air discharged from the first exhaust portion 2302 of the first axial fan 2 from leaking to the outside from the connecting portion between the first axial fan 2 and the second axial fan 3 .

A first support rib 24 is arranged on the exhaust side of the first axial fan 2 . A second support rib 34 is arranged on the intake side of the second axial fan 3 . By connecting the first axial fan 2 and the second axial fan 3 in the axial direction, the surfaces of the first support ribs 24 facing the exhaust side and the surfaces of the second support ribs 34 facing the suction side are separated from each other. , axially overlap. The surface of the first support rib 24 facing the exhaust side and the surface of the second support rib 34 facing the intake side may be in contact with each other, or a gap may be formed to the extent that turbulence does not occur. good. That is, the first support rib 24 is arranged on the exhaust side of the first housing 23, the second support rib 34 is arranged on the intake side of the second housing 33, and the surface of the first support rib 24 facing the exhaust side is The surface of the second support rib 34 facing the intake side overlaps in the axial direction. With this configuration, the first support rib 24 and the second support rib 34 are combined to form a stationary blade. As a result, the velocity component in the rotational direction of the airflow can be directed in the axial direction, and the pressure and flow rate in the axial direction can be increased.

When connecting the first axial fan 2 and the second axial fan 3, the inner plane 2341 of the second inner diameter portion 234 of the first tubular portion 230 and the inner plane 3341 of the second inner diameter portion 334 of the second tubular portion 330 are arranged on the same plane. Further, the inner curved surface 2342 of the second inner diameter portion 234 of the first tubular portion 230 and the inner curved surface 3342 of the second inner diameter portion 334 of the second tubular portion 330 are arranged on the same cylindrical surface. By connecting in this manner, the second inner diameter portion 234 of the first tubular portion 230 and the second inner diameter portion 334 of the second tubular portion 330 are smoothly connected in the axial direction.

That is, the first housing 23 has a square-shaped first exhaust flange portion 2321 with one side larger than the inner diameter of the inner surface of the first tubular portion 230 at the exhaust-side end portion. In addition, the second housing 33 has a square-shaped second intake flange portion 3311 with one side larger than the inner diameter of the inner surface of the second cylindrical portion 330 at the end portion on the intake side. The first exhaust flange portion 2321 and the second intake flange portion 3311 are overlapped and connected in the axial direction. The inner diameter D12 of the overlapping portion and the inner diameter D22 of the portion radially overlapping the corner portion of the second intake flange portion 3311 at the intake-side end portion of the inner surface of the second cylinder portion 330 are the minimum axial diameters of the cylinder portions 230 and 330. It is larger than the inner diameters D11 and D21. By temporarily widening the joint between the first housing 23 and the second housing 33, the flow velocity of the airflow flowing through the cylindrical portion is reduced. As a result, wind noise when the airflow passes through the first support ribs 24 and the second support ribs 34 can be reduced. Thereby, noise and/or vibration can be suppressed. That is, the serial axial fan 1 can be made silent.

In the serial axial fan 1, the first axial fan 2 and the second axial fan 3 are driven simultaneously. As a result, in the serial axial fan 1 , air is sucked from the first intake section 2301 by the rotation of the first impeller 21 . The first impeller 21 then compresses and accelerates the air and discharges it from the first exhaust section 2302 . The air discharged from the first exhaust portion 2302 of the first axial fan 2 flows into the second axial fan 3 from the second intake portion 3301 while being prevented from leaking to the outside. In the second axial fan 3 , the rotation of the second impeller 31 further compresses and accelerates the air that has flowed in, and the air is discharged from the second exhaust section 3302 . That is, in the serial axial fan 1, air is sucked from the first intake portion 2301 at the end of the upper IS of the first axial fan 2, compressed and accelerated by the first impeller 21 and the second impeller 31, and then The air is discharged from the second exhaust part 3302 at the lower end of the axial fan 3 . The second inner diameter portion 234 of the first cylindrical portion 230 and the second inner diameter portion 334 of the second cylindrical portion 330 are smoothly connected in the axial direction, thereby reducing airflow turbulence and suppressing a decrease in air volume and pressure. can.

In the wind tunnel of the serial axial fan 1 formed by connecting the first cylindrical portion 230 and the second cylindrical portion 330, the connecting portion between the first axial fan 2 and the second axial fan 3, that is, the central portion in the axial direction and the inner diameter increases. As a result, the flow velocity of the airflow discharged from the first exhaust section 2302 of the first axial fan 2 is reduced. As a result, wind noise when passing through the first support rib 24 arranged at the lower end of the first cylinder portion 230 and the second support rib 34 arranged on the intake side of the second housing 33 can be reduced. .

By arranging the surfaces of the first support ribs 24 facing the exhaust side and the surfaces facing the intake side of the second support ribs 34 so as to overlap each other in the axial direction, the first support ribs 24 and the second support ribs 34 form a stator blade. configure. The first support rib 24 and the second support rib 34 have an axially lower side OS that slopes toward the downstream side in the rotational direction of the first impeller 21 . The airflow generated by the rotation of the first impeller 21 has a velocity component that swirls in the rotation direction of the first impeller 21 and an axial velocity component. The stator blades formed by the first support ribs 24 and the second support ribs 34 axially bend the velocity component in the circumferential direction of the airflow. This makes it possible to increase axial pressure and flow velocity. In addition, by providing a gap between the first support rib 24 and the second support rib 34, the vibration of the armature 2223 and the armature 3223 is suppressed from being directly transmitted to each other, resulting in large vibration and/or ) noise can be suppressed. That is, the serial axial fan 1 can be made silent.

The first axial fan 2 has an auxiliary blade portion 213 on the radial outer edge of the first blade 211 of the first impeller 21 to increase the pressure of the airflow discharged from the first exhaust portion 2302 . A high-pressure airflow is discharged from the first axial fan 2 . Then, the high-pressure airflow discharged from the first exhaust portion 2302 of the first axial fan 2 flows into the second axial fan 3 from the second intake portion 3301 .

On the other hand, the number of blades of the second axial fan 3 is larger than the number of the first blades 211 of the first impeller 21, and the inclination of the blades of the two-axial fan 3 with respect to the axis is the same as the inclination of the first blades 211. small in comparison. Therefore, the second axial fan 3 is more effective than the first axial fan 2 in increasing the flow rate of the airflow. The second axial fan 3 accelerates the high-pressure airflow from the first axial fan 2 to increase the flow rate. As a result, the serial axial fan 1 can discharge a high-pressure airflow with a large flow rate.

As described above, the first axial fan 2 includes the auxiliary blade portion 213 on the radially outer edge portion of the first blades 211 of the first impeller 21, thereby increasing the pressure of the airflow generated by the first impeller 21. It is carried out. The first axial fan 2 is highly effective in increasing the pressure. The second axial fan 3 is highly effective in increasing the flow velocity, that is, increasing the flow rate.

<Example> The characteristics of the serial axial flow fan 1 of the present invention were evaluated using a computer simulation. In the serial axial fan 1, Nin is the number of blades of the impeller of the axial fan on the intake side, Nout is the number of blades of the impeller of the axial fan of the exhaust side, and the number of the first supporting rib and the second supporting rib. was set to Nrib, and Nin, Nout and Nrib were changed to perform simulations. In addition, in a configuration based on the present invention, an auxiliary wing portion is formed on the radially outer edge portion of the blade of the impeller of the axial fan, the outer side of which is curved toward the intake side.

As a conventional example, Nin = 5, Nout = 7, and Nrib = 11, and the maximum efficiency point, discharge pressure, and flow rate when no aileron is provided were measured. As an example, Nin=5, Nout=7, N=11, and the same measurement as the conventional example was performed with a configuration in which an aileron portion was provided on the radially outer edge portion of the blade on the intake side.

As a result, the maximum efficiency point of the conventional example was 46%, whereas the maximum efficiency of the example increased to 47%. Further, the pressure when the flow rate of the discharged airflow was 4.0 cubic meters per minute was about 1230 Pa in the conventional example, whereas it was about 1250 Pa in the example. The input shaft power at this time was 168 W in the conventional example, whereas it was 165 W in the embodiment.

As a result, the embodiment has a higher maximum efficiency point and a higher pressure at the same flow rate than the conventional example. Also, in the example, although the pressure-flow rate characteristics are higher than in the conventional example, the input shaft power is lower.

As a result of the simulation, in the configuration of Nin<Nout<Nrib, by providing the aileron portion on at least one of the intake side blade and the exhaust side blade, higher efficiency, higher pressure, and larger air volume can be achieved compared to the case where there is no aileron. It was found that there is a case where

Note that Nin, Nout and Nrib are sets of relatively prime integers. In other words, Nin, Nout and Nrib are a set of integers that have no common divisors other than one. By configuring in this way, the resonance of the vibrations of the first impeller 21, the second impeller 31, the first support ribs 24, and the second support ribs 34 is suppressed. That is, the noise caused by resonance can be suppressed, and the serial axial fan 1 can be made silent.

In addition, similar simulations were performed with Nin<Nout<Nrib, providing an aileron on the intake-side blade, and changing Nin, Nout, and Nrib. Example when (Nin, Nout, Nrib) = (5, 7, 11), Comparative Example 1 when (Nin, Nout, Nrib) = (4, 7, 11), (Nin, Nout, Nrib) = (5, 9, 11) for Comparative Example 2, (Nin, Nout, Nrib) = (5, 11, 11) for Comparative Example 3, (Nin, Nout, Nrib) = (5, 7, 13) for Comparative Example 4.

The pressure when the flow rate of the discharged air is 4.0 cubic meters per minute is about 800 kPa in Comparative Example 1, about 990 kPa in Comparative Example 2, about 1150 kPa in Comparative Example 3, and about 990 kPa in Comparative Example 4. rice field.

The number of blades Nin of the impeller in the axial fan on the intake side is five in the embodiment and four in the first comparative example. It can be seen that the pressure of the exhausted air varies depending on the number of blades Nin of the impeller in the axial fan on the intake side.

Further, the number of blades Nout of the impeller of the axial flow fan on the exhaust side is 7 in the embodiment, 9 in the second comparative example, and 11 in the third comparative example. It can be seen that the pressure of the exhausted air also varies depending on the number of blades Nout of the impeller of the axial flow fan on the exhaust side. The pressure of the exhausted air is higher when Nout=11 than when Nout=9. Furthermore, it can be seen that when Nout=7, it is even higher.

Further, the number Nrib of the first supporting ribs and the second supporting ribs is 11 in the example and 13 in the fourth comparative example. It can be seen that the pressure of the exhausted air varies depending on the number Nrib of the first supporting ribs and the number Nrib of the second supporting ribs. The pressure of the exhausted air is higher when Nrib=11 than when Nrib=13.

That is, it can be seen that the pressure-flow characteristics of the discharged airflow are higher in the example than in the comparative examples 1 to 4.

As a result of more simulations, it was confirmed that a blade with Nin=5 and an aileron portion is optimal for increasing the pressure of the airflow. Moreover, it was confirmed that setting Nout=7 makes it possible to increase the inclination of the blade and maintain the blade area, which is optimal for increasing the air volume. Furthermore, by setting Nrib to 11, it was confirmed that the maximum pressure and the maximum wind force can be obtained while ensuring the necessary mechanical strength to stably support the first motor section and the second motor section at the highest efficiency point. did.

In the present invention, the first impeller 21 and the second impeller 31 rotate in the same direction. Therefore, by making the circumferential velocity component of the airflow discharged from the first axial fan 2 and the rotational direction of the second impeller 31 the same direction, the rotational velocity of the airflow and the rotational direction of the second impeller 31 Since the relative speed in the rotational direction of the upstream end of the second blade 311 is reduced, vibration and noise can be suppressed. That is, the serial axial fan 1 can be made silent. In addition, since the above direction is the same as the direction of air flow into which the second blade 311 flows, the resistance of the second blade 311 can be suppressed. As a result, the input shaft power can be suppressed.

It should be noted that the inclination direction of the second blades 311 of the second impeller 31 may be opposite and the rotation direction of the second impeller 31 may be opposite to the rotation direction of the first impeller 21 . As a result, the effect of the second blades 311 of the second impeller 31 to bend the velocity component in the rotational direction of the airflow in the axial direction is enhanced. This makes it possible to increase the pressure of the airflow discharged from the serial axial fan 1 .

Further, in the present embodiment, the first axial fan 2 is provided with the first blade 211 having the auxiliary blade portion 213 on the radially outer edge portion, but the present invention is not limited to this. The second blade 311 provided in the second axial fan 3 may be provided with an auxiliary blade portion on the outer edge portion in the radial direction. In addition, the radially outer edge portions of both the first blade and the second blade may be provided with auxiliary blade portions. That is, at least one of the first wing 211 and the second wing 311 has the aileron 213 .

Important performances in axial fans include pressure and airflow. According to the DC axial flow fan 1 of the present invention, the two impellers 21 and 31 are divided into one for pressure (first impeller 21) and one for air volume (second impeller 31). and air volume can be secured. That is, by attaching the aileron (aileron portion 213) to the impeller (first impeller 21), a high pressure can be obtained and the impeller can be used as a pressure impeller. The pressure impeller (first impeller 21) has a large pressure difference between the pressure surface and the negative pressure surface. Therefore, air leaks from the gap between the outer peripheral portion of the impeller (first blade 211) and the inner peripheral surface of the housing (the inner peripheral surface of the first cylindrical portion 230), increasing the pressure loss. A pressure loss can be reduced by providing an aileron (aileron portion 213) on the outer peripheral portion of the impeller (first impeller 21). On the other hand, since the impeller (the second impeller 31) is not provided with ailerons, it can be used as an air volume impeller with a large air volume. The impeller for air volume (second impeller 31) can obtain a large air volume by pushing the air with its entire surface. In other words, by combining the impeller for pressure (first impeller 21) and the impeller for air volume (second impeller 31), it is possible to obtain airflow of high pressure and large volume.

Although the embodiments of the present invention have been described above, various modifications of the embodiments are possible within the scope of the present invention.

The serial axial flow fan according to the present invention can be used as a cooling fan for blowing air to electronic components arranged in equipment such as computers, network communication devices, and servers to cool the electronic components.

REFERENCE SIGNS LIST 1 serial axial fan, 2 first axial fan, 21 first impeller, 211 first blade, 212 cup, 213 aileron, 22... First motor section 221... First rotor section 2211... Yoke 2212... Field magnet 2213... Shaft 2214... Shaft fixing member 222... First stator portion 2221 Base portion 2222 Bearing holding portion 2223 Armature 2224 Circuit board 2225 Ball bearing 2226 Ball bearing 2227 ... stator core 2228 ... coil, 2229 ... insulator, 23 ... first housing, 230 ... first cylindrical portion, 2301 ... first intake section, 2302 ... first exhaust section , 231 ... upper end portion 2311 ... first intake flange portion 232 ... lower end portion 2321 ... first exhaust flange portion 233 ... first inner diameter portion 234 ... second Inner diameter portion 2341 Inner flat surface 2342 Inner curved surface 235 Conical portion 236 Outer flat surface 24 First supporting rib 3 Second axial fan 31... second impeller, 311... second blade, 312... cup, 32... second motor section, 321... second rotor section, 3211... yoke, 3212... Field magnet 3213 Shaft 3214 Shaft fixing member 322 Second stator portion 3221 Base portion 3222 Bearing holding portion 3223 Armature 3224... circuit board, 3225... ball bearing, 3226... ball bearing, 3227... stator core, 3228... coil, 3229... insulator, 33... second housing, 330... Second cylindrical portion 3301 Second intake portion 3302 Second exhaust portion 331 Upper end portion 3311 Second intake flange portion 332 Lower end portion 3321 Second exhaust flange portion 333 First inner diameter portion 334 Second inner diameter portion 3341 Inner plane 3342 Inner curved surface 335 Conical portion 336・Outer plane, 337 ... enlarged diameter portion, 34 ... second support rib

An exemplary serial axial fan of the present invention includes a first axial fan for blowing air taken in from an intake side and blowing air from an exhaust side, and a first axial fan connected along the central axis of the first axial fan to take in air from the intake side. a second axial fan for blowing air from the exhaust side, wherein the end of the first axial fan on the exhaust side and the end of the second axial fan on the intake side are connected to each other. The first axial fan includes a first impeller that rotates around the central axis, a first motor unit that rotates the first impeller, and a first cylinder that surrounds the radially outer side of the first impeller. and a first support rib extending inward from the inner surface of the first tubular portion and supporting the first motor portion, wherein the first impeller extends radially outward and extends circumferentially. The second axial fan includes a plurality of first blades arranged in a direction, the second axial fan includes a second impeller rotating around the central axis, a second motor section rotating the second impeller, and the second a second housing including a second tubular portion surrounding the radially outer side of the impeller; and second support ribs extending inwardly from an inner surface of the second tubular portion and supporting the second motor portion, the second impeller comprising: comprises a plurality of second blades extending radially outward and arranged in the circumferential direction, the second blades having a smaller inclination with respect to the central axis than the first blades, the first blades and the second blades Among them, only the first blade has an auxiliary blade portion on a radially outer edge portion, and the auxiliary blade portion is a serial axial flow fan that curves toward the intake side as it goes radially outward.

Claims (9)

a first axial fan that blows out the air taken in from the intake side from the exhaust side; and a first axial fan that is connected to the first axial fan along the central axis of the first axial fan and blows out the air taken in from the intake side from the exhaust side. a second axial fan, wherein an exhaust-side end of the first axial fan and an intake-side end of the second axial fan are connected; A uniaxial flow fan includes a first housing that includes a first impeller that rotates about the central axis, a first motor section that rotates the first impeller, and a first cylindrical section that surrounds the radially outer side of the first impeller. and a first support rib that extends inward from the inner surface of the first cylindrical portion and supports the first motor portion, wherein the first impeller extends radially outward and is arranged in the circumferential direction. The second axial fan comprises: a second impeller that rotates around the central axis; a second motor unit that rotates the second impeller; and a radially outer side of the second impeller a second housing including a surrounding second cylindrical portion; and second support ribs extending inwardly from an inner surface of the second cylindrical portion and supporting the second motor portion, wherein the second impeller extends radially outward. a plurality of second blades that extend and are arranged in a circumferential direction, wherein only the first blade of the first blade and the second blade has an aileron portion on a radially outer edge thereof, the aileron portion being , a serial axial flow fan that curves toward the intake side as it goes radially outward. 2. The serial axial flow fan according to claim 1, wherein the auxiliary blade portion is formed over the entire area from the front end in the rotational direction of the outer edge portion to the rear end in the rotational direction. 3. The serial axial flow fan according to claim 1, wherein the auxiliary blade portion is accommodated inside the axial length of the first tubular portion or the second tubular portion. A radial gap between a side of an inner surface of the first cylindrical portion or the second cylindrical portion radially facing the aileron portion and a radially outer side of the aileron portion is uniform. 4. The serial axial flow fan according to any one of 3. 5. The in-line axial flow engine according to claim 1, wherein at least a portion of the inner surface of the first cylindrical portion or the second cylindrical portion that faces the aileron portion in a radial direction is a cylinder. fan. The first support rib is arranged on the exhaust side of the first housing, the second support rib is arranged on the intake side of the second housing, and the surface of the first support rib facing the exhaust side and the first support rib are arranged on the exhaust side. 6. The serial axial flow fan according to claim 1, wherein the surfaces of the two support ribs facing the intake side overlap in the axial direction. The first housing has a square-shaped first exhaust flange part whose one side is larger than the inner diameter of the inner surface of the first cylindrical part at the end on the exhaust side, and the second housing has one side at the end on the intake side. is larger than the inner diameter of the inner surface of the second tubular portion, the first exhaust flange portion and the second intake flange portion are axially overlapped and connected, and the second A portion radially overlapping a corner of the first exhaust flange at the exhaust-side end of the inner surface of the first cylinder, and a corner of the second intake flange at the intake-side end of the inner surface of the second cylinder. 7. The series shaft according to claim 1, wherein the inner diameter of the portion overlapping the direction is larger than the minimum axial inner diameter of the first tubular portion and the minimum axial inner diameter of the second tubular portion. flow fan. The second housing includes a square-shaped second exhaust flange portion whose one side is larger than the inner diameter of the inner surface of the second cylindrical portion at the exhaust side end portion, and a second exhaust flange portion at the exhaust side end portion of the inner surface of the second cylindrical portion. 8. The serial axial flow fan according to claim 1, wherein a portion radially overlapping a corner portion of the second exhaust flange portion curves radially outward toward an edge on the exhaust side. The first cylindrical portion includes a first large inner diameter portion having an inner diameter larger than that of the intake side on the exhaust side, and the second cylindrical portion includes a second large inner diameter portion having an inner diameter larger than that of the exhaust side on the intake side, The first large inner diameter portion includes a first inner flat surface and a first inner curved surface radially overlapping a corner portion of the first exhaust flange and having a longer distance from the central axis than the first inner flat surface. The second large inner diameter portion includes a second inner flat surface and a second inner curved surface radially overlapping a corner portion of the second intake flange and having a longer distance from the central axis than the second inner flat surface. , wherein the first support ribs are provided on each of the first inner flat surface and the first inner curved surface; and the second support ribs are provided on each of the second inner flat surface and the second inner curved surface. 9. The serial axial flow fan according to any one of claims 1 to 8, provided in the .

Images