JP5375099B2 - Inline axial fan - Google Patents

Description

  The present invention relates to a series axial fan.

  In electronic devices such as personal computers and network servers, cooling fans are provided to cool the electronic components inside the housing, and the performance of the cooling fans increases as the mounting density of electronic components inside the housing increases. There is a further need for improvement. In particular, a cooling fan mounted on a relatively large electronic device such as a server is required to have a high static pressure and a large air volume. In response to such a demand, for example, a serial axial fan in which two moving blades are coaxially connected along a predetermined central axis is provided (see, for example, Patent Document 1).

Japanese Patent No. 3717803

  By the way, in order to effectively cool the electronic components inside the electronic device, it is necessary to supply cooling air directly to the electronic components. In a general axial fan, the air flow from the axial fan tends to spread outward in the radial direction with respect to the rotating shaft of the impeller due to the influence of centrifugal force accompanying the rotation of the impeller. For this reason, when an axial flow fan is used as a cooling fan, there is a problem that sufficient cooling air is not supplied to the electronic component due to the expansion of the air flow.

  The present invention has been made in view of the above problems, and an object thereof is to regulate the outflow direction of an air flow so that the air flow of a series axial fan does not spread outward in the radial direction.

A serial axial fan according to the present invention includes a first impeller having a plurality of first blades arranged around a rotation center axis and generating an air flow in a direction along the rotation center axis by rotation, and a rotation center A first motor unit that rotates the first impeller about the shaft; and a plurality of second blades that are arranged adjacent to the first impeller in the axial direction and are arranged around the rotation center axis. A second impeller that generates an air flow in the same direction as the air flow generated by the first impeller, a second motor unit that rotates the second impeller about the rotation center axis, and the first and second impellers are surrounded in the radial direction. Between the cylindrical housing and the first impeller and the second impeller, they are provided radially about the rotation center axis, and the respective outer front ends are connected to the housing so that at least the first motor portion is housed. A plurality of support ribs for supporting the first impeller side end edge in an arbitrary radial cross section on the upstream side of the second impeller side end edge in the rotational direction of the first impeller. The inclined surface is inclined so as to face the first impeller side of the support rib, and the angle of the inclined surface with respect to the direction of the rotation center axis and the angle of the air flow generated by the first impeller with respect to the direction of the rotation center axis And the angle with respect to the direction of the rotation center axis of the inclined surface is substantially the same at the upper end and the lower end of the inclined surface, and the upper end and the lower end are connected by a flat surface or a smooth curved surface, The inclination angle of the inclined surface of each support rib is formed so as to decrease from the inner side to the outer side in the radial direction perpendicular to the rotation center axis .

  In such a series axial fan, each first blade of the first impeller is tilted such that the blade leading edge is positioned in the rotational direction with respect to the blade trailing edge, and at least the blade trailing edge of each first blade is The angle formed with the inclined surface of the support rib can be set to 100 degrees or less, and desirably, this angle is set in the range of 80 degrees to 100 degrees.

  Each support rib may have a shape that is inclined or curved in the rotation direction or the counter-rotation direction of the first impeller with respect to the radial line perpendicular to the rotation center axis from the innermost end on the first motor unit side. In this case, the shape in which the support rib is inclined or curved is intended to be a shape other than the radial straight line connecting the shortest distance from the first motor portion side to the connection end of the housing.

The housing in the serial axial fan of the present invention can be composed of a first housing member surrounding the outer periphery of the first impeller and a second housing member surrounding the outer periphery of the second impeller. In addition, the first impeller rotated by the first motor unit and the second impeller rotated by the second motor unit may rotate in the same direction so that the rotation directions of the first impeller and the second impeller are reversed. You can also.

  Each of the support ribs includes a plurality of first support ribs that are provided radially from the first motor portion and whose outer ends are connected to the housing to support the first motor portion with respect to the housing, and the second motor portion. And a plurality of second support ribs that are provided radially from the outer ends of the second motor portion and are connected to the housing to support the second motor portion with respect to the housing. In this case, the first support rib and the second support rib are provided. The support ribs are arranged between the first impeller and the second impeller, the number of the first support ribs and the second support ribs is the same, and the rotation centers of the first support ribs and the second support ribs You may make it comprise the said inclined surface by making it contact in the direction of an axis | shaft.

  Further, the housing surrounds the first impeller in the radial direction and is connected to the plurality of first support ribs, and surrounds the second impeller in the radial direction and is connected to the plurality of second support ribs. It can comprise with a 2nd housing member. Also in this case, the second impeller may be rotated in the direction opposite to the rotation direction of the first impeller.

Another serial axial fan of the present invention includes a first impeller having a plurality of first blades arranged around a rotation center axis and generating an air flow in a direction along the rotation center axis by rotation, A first motor unit that rotates the first impeller about the rotation center axis; and a plurality of second blades that are arranged adjacent to the first impeller in the axial direction and are arranged around the rotation center axis; A second impeller that generates an air flow in the same direction as the air flow generated by the first impeller by rotation, a second motor unit that rotates the second impeller about the rotation center axis, and the first and second impellers in the radial direction Between the first impeller and the second impeller, and are provided radially with the rotation center axis as a center, and the respective outer tips are connected to the housing so that at least the first motor portion is housed. A plurality of support ribs for supporting the first impeller in an arbitrary radial cross section, and an upstream side in the rotational direction of the first impeller from an end edge on the second impeller side. An inclined surface that is inclined so as to be located at the first impeller side of the support rib is provided, the direction of the air flow of the air generated by the first impeller of the first impeller is substantially parallel to the inclined surface , and the inclined surface The angle with respect to the direction of the rotation center axis is substantially the same at the upper end and the lower end of the inclined surface, and the upper end and the lower end are connected by a flat surface or a smooth curved surface, and the inclined surface of each support rib is inclined. The angle is formed so as to become smaller from the inner side to the outer side in the radial direction perpendicular to the rotation center axis .

  In the present invention, not only the air volume characteristics (air volume and static pressure) of the series axial fan are improved, but also it is possible to suppress the outward expansion of the air flow discharged from the series axial fan. is there. As a result, the air flow discharged from the serial axial fan is efficiently supplied to the object to be cooled, such as an electronic component, and the cooling efficiency is improved.

It is a perspective view which shows the serial type axial flow fan which concerns on one embodiment of this invention. It is a disassembled perspective view of the serial axial fan of FIG. It is a longitudinal cross-sectional view of the serial axial fan of FIG. It is a top view of the 1st axial flow fan of the series type axial flow fan of FIG. It is a top view of the 2nd axial fan of the serial type axial fan of FIG. It is a perspective view which shows the contact state of the 1st support rib and the 2nd support rib in the serial axial fan of FIG. FIG. 2 is a plan view of the serial axial fan (without impeller) of FIG. 1. It is sectional drawing of the 1st support rib and the 2nd support rib in the serial axial fan of FIG. FIG. 2 is a cross-sectional view of the first blade, the first support rib, the second support rib, and the second blade in the series axial fan of FIG. 1 cut in an axial direction along an arc having an arbitrary diameter centered on the central axis J. is there. It is a figure which shows the modification of the support rib obtained by combining a 1st support rib and a 2nd support rib.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inline axial fan 21 1st impeller 22 1st motor part 23 1st housing 24 1st support rib 31 2nd impeller 32 2nd motor part 33 2nd housing 34 2nd support rib 211 1st blade | wing 243 upper end surface 311 Second wing 441 Support rib first side 442 Support rib second side J Central axis

  A preferred embodiment of the present invention will be described in detail with reference to FIGS. In the description of the present invention, when the positional relationship and direction between different components are described using “top”, “bottom”, “left”, and “right”, they indicate the direction and orientation in the drawings. Shall. It does not indicate the direction and orientation after these components are assembled. In the following description, the “axial direction” is a direction parallel to the rotation axis, and the “radial direction” is a direction perpendicular to the rotation axis.

  FIG. 1 is a perspective view showing an inline axial fan 1 according to an embodiment of the present invention. FIG. 2 is an exploded perspective view showing the serial axial fan 1. The serial axial fan 1 is used, for example, as an electric cooling fan for air-cooling electronic devices such as servers. As shown in FIG. 1, the series axial fan 1 is connected to the first axial fan 2 disposed on the upper side in FIG. 1 and the first axial fan 2 along the central axis J1. 1 is provided with a second axial flow fan 3 disposed on the lower side in the first. The first axial fan 2 and the second axial fan 3 are connected and integrated by screws (not shown) or the like. At that time, as shown in FIG. 3, the series axial fan 1 is fixed to the exhaust side of the first axial fan 2 in a state where the second axial fan 3 is reversed with respect to the direction of the central axis J.

  The serial axial fan 1 according to the present embodiment is a so-called counter-rotating axial fan, and the first impeller 21 of the first axial fan 2 and the second axial fan 3 shown in FIG. When the impeller 31 rotates in directions opposite to each other, air is taken in from the upper side (that is, the first axial fan 2 side) in FIG. 1 and moves downward (that is, the second axial fan 3 side). As a result, an air flow in the direction of the central axis J is generated. In the following description, in the direction of the central axis J, the upper side in FIG. 1 that is the side from which air is taken in is referred to as the “intake side”, and the lower side in FIG. " In the serial axial fan 1, the rotation direction of the first impeller 21 and the rotation direction of the second impeller 31 shown in FIG. 2 are opposite to each other, compared to the case where the two impellers rotate in the same direction. High static pressure and large air volume can be realized.

  3 is a longitudinal sectional view of the serial axial fan 1 cut along a plane including the central axis J, and FIG. 4 is a plan view of the first axial fan 2 viewed from the intake side. Impeller As shown in FIGS. 3 and 4, the first axial fan 2 includes a first impeller 21 having seven first blades 211 arranged at an equal pitch in the circumferential direction around the central axis J, the center By rotating the first impeller 21 about the axis J clockwise in FIGS. 2 and 4, the flow of air in the direction along the central axis J, that is, the air from the upper side to the lower side in FIG. The first motor unit 22 that generates the flow of the first, the first housing 23 that surrounds the first impeller 21 in the radial direction, and the lower side of the first impeller 21, that is, between the first impeller 21 and the second impeller 31. The first motor part 22 includes a plurality of first support ribs 24 that extend radially about the central axis J and that have respective distal ends connected to the first housing 23 to support the first motor part 22. . In the present embodiment, there are four first support ribs 24. In the first axial fan 2, the first impeller 21, the first motor unit 22, and the first support rib group are disposed inside the first housing 23. An arrow R1 in FIG. 4 indicates the rotation direction of the first impeller 21.

  In FIG. 3, for convenience of illustration, the first blade 211 and the first support rib 24 each have a schematic shape viewed from the side, and each component of the first motor unit 22 has a cross-section. Illustration of parallel diagonal lines is omitted. Further, the second blades 311 and the second support ribs 34 of the second axial fan 3 to be described later also show the schematic shapes of the second blades 311 and the second support ribs 34 as seen from the side, similarly to the first blades 211 and the first support ribs 24. Similarly to the first motor unit 22, the configuration of the second motor unit 32 is also omitted from the illustration of the parallel diagonal lines representing the cross section.

  As shown in FIG. 3, the first motor unit 22 includes a stator unit 221 that is a fixed assembly and a rotor unit 222 that is a rotating assembly. The rotor unit 222 has a central axis via a bearing mechanism described later. The stator portion 221 is supported so as to be rotatable around J. In the following description, for convenience, the rotor portion 222 side is described as the upper side and the stator portion 221 side is the lower side along the central axis J, but the central axis J does not necessarily coincide with the direction of gravity.

  The stator portion 221 includes a substantially annular base portion 2211 centering on the central axis J in plan view, and the base portion 2211 is interposed via a plurality of first support ribs 24 as shown in FIGS. The first housing 23 is fixed to the substantially cylindrical inner peripheral surface 231 and holds each part of the stator part 221. The base portion 2211 is made of resin, and is formed by injection molding together with the plurality of first support ribs 24 and the first housing 23 that are also made of resin.

  As shown in FIG. 3, a substantially cylindrical bearing holding portion 2212 that protrudes upward from the base portion 2211 (that is, the rotor portion 222 side) is fixed to the center portion of the base portion 2211. Inside the bearing holding portion 2212, ball bearings 2213 and 2214 that are part of the bearing mechanism are provided at the upper and lower portions in the central axis J direction.

  The stator portion 221 is also attached to the lower side of the armature 2215 and the armature 2215 attached to the outer periphery of the bearing holding portion 2212 and is electrically connected to the coil of the armature 2215 to control energization of the coil. A circuit board 2216 having a substantially annular plate shape incorporating a control circuit is further provided. The circuit board 2216 is connected to an external power source provided outside the serial axial fan 1 through a lead wire group in which a plurality of lead wires are bundled. In FIG. 3, the lead wire group and the external power supply are not shown.

  The rotor portion 222 has a substantially cylindrical shape centered on the central axis J, and has a lid portion and is formed of a magnetic metal material. The rotor portion 222 is fixed to the inner surface of the peripheral wall portion of the yoke 2221 and is armature. A substantially cylindrical field magnet 2222 facing 2215 and a shaft 2223 projecting downward from the center of the lid of the yoke 2221 are provided.

  The shaft 2223 is inserted into the bearing holding portion 2212 and is rotatably supported by ball bearings 2213 and 2214. In the first axial fan 2, the shaft 2223 and the ball bearings 2213 and 2214 serve as a bearing mechanism that rotatably supports the yoke 2221 with respect to the base portion 2211 around the central axis J.

  The first impeller 21 has a substantially cylindrical lid 212 with a lid that covers the outer side of the yoke 2221 of the first motor unit 22, and extends radially from the outer side (that is, the outer surface) of the peripheral wall of the hub 212, and the like in the circumferential direction. A plurality of first blades 211 arranged at intervals are provided. In this embodiment, the hub 212 is made of resin, and is formed by injection molding together with the first wings 211 made of resin.

  In the first axial fan 2, a drive current is supplied to the armature 2215 via the circuit board 2216 of the first motor unit 22, and the central axis J is centered between the armature 2215 and the field magnet 2222. Torque is generated, and the drive current is controlled by the control circuit, whereby the plurality of first blades 211 of the first impeller 21 attached to the rotor portion 222 are predetermined in the clockwise direction in FIG. It rotates at the number of rotations. In this embodiment, it rotates at about 10,000 rpm. Thereby, air is taken in from the upper side in FIG. 3, that is, the rotor part 222 side of the first motor part 22, and is sent to the lower side, that is, the second axial fan 3 side.

  FIG. 5 is a plan view of the second axial fan 3 as viewed from the intake side. As shown in FIGS. 3 and 5, the second axial fan 3 includes a second impeller 31 disposed adjacent to the first impeller 21 along the central axis J, and the second impeller 31 has a central axis. It has five second blades 311 extending radially around J and arranged at equal pitches in the circumferential direction.

  The second axial fan 3 also rotates the second impeller 31 around the central axis J in the direction opposite to the first impeller 21, that is, counterclockwise in FIG. 5 and in the direction indicated by the arrow R2. Accordingly, the second motor unit 32 and the second motor unit 32 generate the air flow in the same direction as the air flow by the first impeller 21, that is, the air flow in the central axis J direction from the upper side to the lower side in FIG. A second housing 33 that surrounds the impeller 31 in the radial direction and a lower side of the second impeller 31, that is, a side opposite to the first impeller 21 of the second impeller 31, centering on the central axis J from the second motor portion 32. A plurality of second support ribs 34 that extend radially and are connected to the second housing 33 and support the second motor portion 32 are provided. In the present embodiment, the number of the second support ribs 34 is four as with the first support ribs 24.

  In the second axial fan 3, the second impeller 31, the second motor unit 32, and the second support rib group are disposed inside the second housing 33. In addition, when viewed as a series axial fan 1 as a whole, the flow path through which air flows inside the continuous first housing 23 and second housing 33 is in order from the upper side (ie, the intake side) in FIG. The first impeller 21, the first support rib group, the second support rib group, and the second impeller 31 are disposed. At that time, the support ribs of the first support rib group and the second support rib group are in contact with each other in the central axis J direction.

As shown in FIG. 3, the configuration of the second motor unit 32 is the same as the configuration of the first motor unit 22, and the stator unit 321 and the stator unit 321 are arranged below the stator unit 321 (that is, on the exhaust side). The rotor part 322 supported rotatably with respect to the part 321 is provided.

  The stator portion 321 is fixed to a substantially cylindrical inner peripheral surface 331 of the second housing 33 via a plurality of second support ribs 34 and includes a base portion 3211 that holds each portion of the stator portion 321, and ball bearings 3213 and 3214. A substantially cylindrical bearing holding portion 3212 provided inside, an armature 3215 attached to the outer periphery of the bearing holding portion 3212, and attached to the lower side of the armature 3215 and electrically connected to a coil of the armature 3215. A substantially annular plate-like circuit board 3216 incorporating a control circuit for controlling energization of the coil is provided.

  In the present embodiment, the base portion 3211 is made of resin, and is formed by injection molding together with the plurality of second support ribs 34 and the second housing 33 that are also made of resin. The circuit board 3216 is connected to an external power source provided outside the serial axial fan 1 through a lead wire group in which a plurality of lead wires are bundled.

  The rotor portion 322 includes a metal yoke 3221, a field magnet 3222 fixed to the inner surface of the yoke 3221, and a shaft 3223 that protrudes downward from the yoke 3221. The shaft 3223 is rotatably supported by ball bearings 3213 and 3214 in the bearing holding portion 3212. In the second axial fan 3, the shaft 3223 and the ball bearings 3213 and 3214 serve as a bearing mechanism that rotatably supports the yoke 3221 with respect to the base portion 3211 around the central axis J.

  The second impeller 31 includes a substantially cylindrical covered hub 312 that covers the outer side of the yoke 3221 of the second motor unit 32, and a plurality of second blades 311 that extend radially from the outer peripheral surface of the peripheral wall of the hub 312. The hub 312 is made of resin, and is formed by injection molding together with the second wing 311 made of resin.

In the second axial fan 3, when the second motor unit 32 is driven, the plurality of second blades 311 of the second impeller 31 have a predetermined number of rotations counterclockwise in FIG. Rotate at. In this embodiment, it rotates at about 8000 rpm. Thereby, air is taken in from the upper side in FIG. 3, that is, the second support rib 34 side , and is sent to the lower side, that is, the second axial fan 3 side .

  FIG. 6 is a perspective view showing a contact state between the first support rib 24 and the second support rib 34 of the serial axial fan 1. As shown in FIG. 6, between the first impeller 21 and the second impeller 31, the first support rib 24 and the second support rib 34 provided in the axial fans 2 and 3, respectively, are arranged. The first support ribs 24 are arranged at equal intervals in the circumferential direction, and the second support ribs 34 are also arranged at equal intervals in the circumferential direction. When the first axial fan 2 and the second axial fan 3 are connected by screws or the like, the first support rib 24 and the second support rib 34 abut in the axial direction, and the four second support ribs 34. Are arranged on the second impeller 31 side of the four first support ribs 24, that is, on the exhaust side. Each second support rib 34 is overlapped with the first support rib 24 over the entire length in a plan view, that is, when viewed from the direction of the central axis J. In the following description, the first support rib 24 and the second support rib 34 are collectively referred to as “support rib 44”. In other words, the first motor section 22 and the second motor section 22 are arranged between the first impeller 21 and the second impeller 31 by the plurality of support ribs 44 including the plurality of first support ribs 24 and the plurality of second support ribs 34. The motor unit 32 is supported.

  As described above, the support ribs 44 are configured by overlapping the first support ribs 24 and the second support ribs 34. The support ribs 44 are overlapped at a boundary portion between the first support ribs 24 and the second support ribs 34 with almost no step. In other words, the first support rib first side surface 241 facing the upstream side of the air flow of the first support rib 24 and the second support rib first side surface 341 facing the upstream side of the air flow of the second support rib 34. Thus, a continuous surface having almost no step is formed. Similarly, the first support rib second side surface 242 facing the downstream side of the air flow of the first support rib 24, and the second support rib second side surface 342 facing the downstream side of the air flow of the second support rib 34, Thus, a continuous surface having almost no step is formed. That is, the support rib 44 is originally configured by superimposing the first support rib 24 and the second support rib 34, but is formed as if it were one support rib. Hereinafter, a continuous surface formed by the first support rib first side surface 241 and the second support rib first side surface 341 is referred to as a support rib first side surface 441. A continuous surface formed by the first support rib second side surface 242 and the second support rib second side surface 342 is referred to as a support rib second side surface 442.

  FIG. 7 is a plan view of the serial axial fan viewed from the axial direction. In FIG. 7, the impeller is omitted. FIG. 8 is a cross-sectional view taken along the lines AA, BB, and CC in FIG. 7 in the axial direction. These AA line, BB line, and CC line show arc lines around the central axis J, respectively. FIG. 9 is a cross-sectional view of the first blade 211, the support rib 44, and the second blade 311 cut in the axial direction along an arc having an arbitrary diameter centered on the central axis J. That's it. Further, an arrow R1 in FIG. 9 is the rotation direction of the first impeller 21, and simultaneously indicates the moving direction of the first blade 211. An arrow R2 is the direction of rotation of the second impeller 31, and simultaneously indicates the direction of movement of the second blade 311. As shown in FIG. 8, the longitudinal direction in the cross section of the support rib 44 on the cylindrical surface is inclined with respect to the central axis J so that the upper end in the axial direction is located on the opposite side of the rotation direction of the impeller 21 from the lower end. doing. The support rib 44 is disposed so as to cross the air flow path constituted by the first housing 23 and the second housing 33. Therefore, the support ribs 44 need to be arranged so that the energy loss of the air flow is as small as possible.

  Here, before describing the arrangement of the support ribs 44, the structure of the first blade 211 will be described. As shown in FIG. 4, the shape of the first blade 211 in plan view is not linearly extended in the radial direction, but is directed toward the opposite side of the rotation direction of the first impeller 21 from the inner side to the outer side in the radial direction. The fan shape expands. Further, as shown in FIG. 9, the cross-sectional shape of the first blade 211 on the cylindrical surface centered on the central axis J is such that the upper edge of the first blade 211, that is, the rotational leading edge is lower than the lower edge, that is, the rotational trailing edge. The arc shape is inclined and curved so as to be located downstream of the first impeller 21 in the rotation direction. Usually, the axial fan used for cooling the inside of an electronic device is selected according to the system impedance in the electronic device, the air volume and static pressure of the axial fan. Here, the system impedance means the relationship between the static pressure and the air volume in the electronic device, that is, the difficulty of the air flow in the system, and the resistance of the air flow in the system. In an electronic device, electronic components, power supplies, and the like are often concentrated in a narrow space, resulting in a high system impedance and a large resistance value of airflow in the system. Therefore, high static pressure is required for the axial fan used for cooling the inside of the electronic device.

As a method of achieving high static pressure in the axial fan, there is a method of reducing the interval between the adjacent first blades 211 in a plan view of the first axial fan 2. In this case, the arc length of the arc-shaped portion in the cross section of the first blade 211 on the cylindrical surface may be increased from the radially inner side to the outer side. Here, the arc length of the arc-shaped portion of the first blade 211 means the length of the arc connecting the midpoints in the thickness direction of the arc-shaped portion. However, when the arc length of the arc-shaped portion of the first blade 211 is increased, the height of the first blade 211 in the central axis J direction increases as it goes from the inner side to the outer side in the radial direction. By reducing the difference in the axial height of the first wing 211 between the radially inner side and the outer side, the effective volume occupied by the first wing 211 in the wind tunnel portion formed by the housing, that is, the first wing 211 as viewed from the axial direction. The product of the area and the axial height of the first blade 211 is increased, and the first axial fan 2 that achieves a high static pressure with a high air volume is obtained. As an index for realizing this, as shown in FIG. 9, in the arc-shaped portion of the cross section of the first blade 211 on the cylindrical surface, in particular, the inclination with respect to the central axis J of the trailing edge portion (hereinafter referred to as the first inclination angle α). ) Should increase from the radially inner side to the outer side. The trailing edge portion is located on the downstream side of the air flow, and is also a portion that defines the direction in which the first impeller 21 generates the air flow.

  In order to reduce the airflow loss due to the support rib 44, the side surface of the support rib 44, that is, the support rib first side surface 441 and the support rib second side surface 442 are generated from the first axial fan 2 as shown in FIG. It is preferable that they are arranged so as to be substantially parallel to the flow velocity direction of the air flow, that is, so as to be substantially orthogonal to the rear edge portion of the first blade 211. In other words, the support ribs 44 are preferably arranged so that the projected area of the support ribs 44 becomes the smallest when the support ribs 44 are viewed from the air flow direction. When the air flow and the side surface of the support rib 44 are parallel, the energy passing through the vicinity of the support rib 44 has little energy loss due to the support rib first side surface 441 and the support rib second side surface 442. The upper end surface 243 of the support rib 44 is disposed so as to face the air flow. In the present embodiment, the upper end surface 243 intersects the air flow at an acute angle although it is not parallel to the air flow. . For this reason, the air loss at the time of an airflow interfering with the upper end surface 243 can be suppressed. In the present embodiment, the shape of the upper end surface 243 is a plane, but is not limited to this, and for example, a curved surface may be formed.

  The flow direction of air generated when the first impeller 21 rotates is substantially parallel to the direction of 90 degrees with respect to the trailing edge portion of the first blade 211. That is, if the rear edge portion of the first blade 211 that defines the first inclination angle α and the longitudinal direction of the cross section of the support rib 44 are configured to be 90 degrees, the air flow generated in the first impeller 21 and the support are supported. The longitudinal direction of the cross section of the rib 44 is substantially parallel. However, the flow velocity and angle of the air flow vary depending on the rotation speed of the first impeller 21 and the surrounding environment. In such a case, the angle β with respect to the central axis J in the longitudinal direction of the cross section of the support rib 44 is appropriately changed according to the rotational speed of the first impeller 21 and the surrounding environment. In that case, the angle formed by the trailing edge portion of the first blade 211 and the longitudinal direction of the cross section of the support rib 44 is 100 degrees or less, preferably 80 degrees to 100 degrees. That is, the sum of the first inclination angle α and the longitudinal angle β of the cross section of the support rib 44 is 80 degrees to 100 degrees.

  With the above configuration, the air flow generated by the rotation of the first impeller 21 passes through the support rib 44 with almost no change in the flow direction and with minimal energy loss. The air that has passed through the support rib 44 flows toward the second wing 311. As shown in FIG. 9, the cross-sectional shape of the second blade 311 on the cylindrical surface with the central axis J as the center is the second edge of the second blade 311, that is, the upper edge in the rotational direction is the second edge than the lower edge, that is, the trailing edge in the rotational direction. The arcuate shape is inclined and curved so as to be positioned downstream of the impeller 31 in the rotation direction. The inclination of the leading edge portion of the second blade 311 in the longitudinal direction of the arc-shaped cross section on the cylindrical surface, particularly the upstream side of the air flow, with respect to the central axis J (hereinafter referred to as the second blade inclination angle γ) is It is set smaller than the inflow angle to the second impeller 31 (approximate to the angle β of the support rib 44).

  In general, the air flow of the air discharged from the axial fan has three speed components. That is, three speed components, an axial component (flow velocity in the axial direction), a rotation component (flow velocity in the impeller rotation direction), and a centrifugal component (flow velocity outward in the radial direction). In order to improve the air blowing characteristics of the serial axial fan 1, it is necessary to increase the ratio of the axial component among the three speed components. In other words, it is necessary to convert the rotational component and the centrifugal component into axial components as much as possible.

Next, the effect | action which converts the said rotation component and a centrifugal component into an axial direction component is demonstrated. As shown in FIG. 9, the air entering the second blade 311 collides with the forward blade surface 3111 in the rotation direction of the second blade 311. The second blade 311 is bent so that a portion from the middle to the rear edge thereof is bent forward in the rotation direction, and the forward blade surface 3111 is inclined so as to face radially inward. Therefore, the air that has collided with the second blade 311 is regulated so as to flow inward in the radial direction, and the velocity vector of the air flow is converted. Therefore, the centrifugal direction component among the velocity components of the air flow is directed radially inward. For this reason, it is possible to suppress the outward spread of the airflow in the radial direction.

The swirl component of the air that has entered the second blade 311 is converted into an axial component by colliding with the forward-side blade surface 3111 of the second blade 311. Therefore, the action of the second blade 311 is to convert the rotating component and the centrifugal component into the axial component of the flow velocity of the air discharged from the first blade 211. Thereby, the air flow itself of the air discharged from the serial axial fan 1 is supplied to the member to be cooled without spreading radially outward.

In an axial fan unit with only one impeller (a normal fan that is not in series), even if the optimum blade design can be achieved, it is impossible to make the rotation component accompanying the rotation of the impeller zero. is there. However, in the axial fan 1, the rotating component of the air flow generated by the first impeller 21 can be recovered by the second impeller 31 that rotates in the opposite direction to the first impeller 21. An axial fan having high pressure characteristics can be provided.

The point here is that when the air discharged from the first impeller 21 passes through the support ribs 44, the flow direction of the air flow is not converted. At present, many of the already known series axial fans have a stationary blade disposed between the first impeller and the second impeller. In this case, the rotating component of the flow velocity of the air discharged from the first impeller is recovered by the stationary blade and converted into the axial component. The air flow converted into the axial component by the stationary blade is discharged from the second impeller in a state where the turning component is given by the second impeller. That is, by disposing the stationary blade between the first impeller and the second impeller, the air discharged from the serial axial fan is discharged with a rotating component. For this reason, the air flow generated by this type of series axial fan is exhausted from the series axial fan by the rotating component and then spreads outward in the radial direction. Air flow cannot be supplied. Therefore, in a series axial fan, it is preferable not to provide a stationary blade between the first impeller and the second impeller.

Next, the detailed shape of the support rib 44 in this invention is demonstrated. As described above, the first blade 211 has an arc-shaped cross section that is a cross-sectional shape on a cylindrical surface with the central axis J as the center, and has an inclination angle with respect to the central axis J direction. It gets bigger as you go. Therefore, the flow velocity angle of the airflow generated from the first blade 211 due to the rotation of the first impeller 21 varies depending on the radial position. Specifically, since the inclination angle of the first blade cross section is small on the radially inner side, the air flow velocity angle has a large angle with respect to the central axis J direction. Since the inclination angle of the cross section is large, the airflow velocity angle is small with respect to the central axis J direction. For this reason, in order to reduce the energy loss of the airflow by the support rib 44, it is necessary to change the inclination angle of the support rib 44 depending on the radial direction. In the present invention, the angle formed between the rear edge portion of the first blade 211 having the first inclination angle α and the longitudinal direction of the cross section of the cylindrical surface around the central axis J of the support rib 44 is 100 degrees or less ( Specifically, it is set to be about 80 to 100 degrees. Ideally, the angle is desirably 90 degrees.

The air flow discharged from the first impeller 21 differs not only in the angle with respect to the central axis J but also in the flow velocity itself depending on the radial position. The flow velocity is large on the radially outer side of the first blade 211, and the flow velocity is small on the radially inner side. Therefore, it is desirable to reduce the energy loss of the airflow passing through the support rib 44 on the radially outer side. Further, the cross-sectional shape of the support rib 44 can reduce energy loss as the projected area viewed from the air flow direction is reduced as it goes radially outward. That is, the cross-sectional shape of the support rib 44 may be appropriately changed depending on the radial direction.

The cross-sectional shape of the support rib 44 is ideally as low as possible in air resistance. FIG. 10 shows a modification of the cross-sectional shape of the support rib. The support rib which finished the air flow upstream side of the 1st support rib 24a and the air flow downstream side of the 2nd support rib 34a in the smooth curved surface, respectively may be sufficient. In addition, the support rib may be configured with an acute cross-sectional shape on the air flow upstream side of the first support rib 24b and the air flow downstream side of the second support rib 34b. Furthermore, the first support rib 24c may be a support rib having a smooth curved surface only on the upstream side of the air flow and the second support rib 34c having a rhombus cross section. Alternatively, only the upstream side of the air flow of the first support rib 24d may be a smooth curved surface, while the support rib may gradually narrow in cross section from the first support rib 24d to the second support rib 34d. In addition, the cross-sectional shape may be a streamline shape like the first support rib 24e and the second support rib 34e. In this case, it is possible to further suppress the energy loss of the airflow that passes through the first support rib 24e and the second support rib 34e. However, the support ribs are arranged so that the flow velocity of the air flow exhausted from the first impeller 21 and the longitudinal direction of the cross section of the support rib are the same in any cross-sectional shape.

  Although the preferred embodiments of the present invention have been described above, various modifications and alterations without departing from the scope and spirit of the present invention will be apparent to those skilled in the art. Accordingly, the scope of the invention is defined only by the appended claims.

Claims (11)

A series axial fan,
A first impeller having a plurality of first blades arranged around a rotation center axis and generating an air flow in a direction along the rotation center axis by rotation;
A first motor unit that rotates the first impeller about the rotation center axis;
The first impeller is disposed adjacent to the first impeller in the axial direction, and has a plurality of second wings disposed around the rotation center axis. The rotation causes the air flow in the same direction as the air flow by the first impeller. A second impeller to be generated;
A second motor section for rotating the second impeller about the rotation center axis;
A cylindrical housing surrounding the first impeller and the second impeller in the radial direction;
Between the first impeller and the second impeller, a radial center is provided about the rotation center axis, and each outer tip is connected to the housing to support at least the first motor portion with respect to the housing. A plurality of supporting ribs,
With
Each of the support ribs is inclined and supported so that an end edge on the first impeller side in an arbitrary radial cross section is positioned upstream of an end edge on the second impeller side in the rotation direction of the first impeller. An inclined surface facing the first impeller side of the rib; an angle of the inclined surface with respect to the direction of the rotation center axis; and an angle of an air flow generated by the first impeller with respect to the direction of the rotation center axis. Are almost identical,
The angle of the inclined surface with respect to the direction of the rotation center axis is substantially the same at the upper end portion and the lower end portion of the inclined surface,
The upper end and the lower end are connected by a flat surface or a smooth curved surface,
An in-line axial fan, wherein an inclination angle of an inclined surface of each support rib is formed so as to decrease from an inner side to an outer side in a radial direction perpendicular to the rotation center axis.   Each of the first blades of the first impeller is inclined such that a blade leading edge is positioned in a rotational direction with respect to the blade trailing edge, and at least the blade trailing edge of the first blade and the inclined surface of the support rib The in-line axial fan according to claim 1, wherein an angle between the first axial flow fan and the second axial flow fan is set to 100 degrees or less.   The series axial fan according to claim 2, wherein an angle formed by at least a trailing edge of each of the first blades and an inclined surface of the support rib is set in a range of 80 degrees to 100 degrees. . At any position in the radially extending direction of each of the support ribs, the cross section of the cylindrical surface with the rotation center axis as the center has a different shape from the cross sections of other positions in the extending direction. The in- line axial fan according to claim 1.   Each of the support ribs is inclined or curved in a rotational direction or a counter-rotating direction of the first impeller with respect to a radial straight line perpendicular to the rotation center axis from the innermost end on the first motor portion side. The in-line axial fan according to claim 1.   2. The serial shaft according to claim 1, wherein the housing includes a first housing member surrounding an outer periphery of the first impeller and a second housing member surrounding an outer periphery of the second impeller. Current fan.   The serial axial fan according to claim 1, wherein the second impeller rotates in a direction opposite to a rotation direction of the first impeller. Each of the support ribs is
A plurality of first support ribs provided radially from the first motor portion, each outer tip being connected to the housing to support the first motor portion with respect to the housing;
A plurality of second support ribs provided radially from the second motor part, each of which has an outer tip connected to the housing to support the second motor part with respect to the housing;
The first support rib and the second support rib are disposed between a first impeller and a second impeller,
The same number of the first support ribs and the second support ribs are provided, and the first support ribs and the second support ribs are in contact with each other in the direction of the rotation center axis so that the inclination is achieved. The series axial fan according to claim 1, wherein a surface is formed. The housing surrounds the first impeller in the radial direction and is connected to the plurality of first support ribs, and surrounds the second impeller in the radial direction and connects the plurality of second support ribs. The in-series axial fan according to claim 8 , wherein the in-line axial fan is configured with a second housing member. The serial axial fan according to claim 8 , wherein the second impeller rotates in a direction opposite to a rotation direction of the first impeller. A series axial fan,
A first impeller having a plurality of first blades arranged around a rotation center axis and generating an air flow in a direction along the rotation center axis by rotation;
A first motor unit that rotates the first impeller about the rotation center axis;
The first impeller is disposed adjacent to the first impeller in the axial direction, and has a plurality of second wings disposed around the rotation center axis. The rotation causes the air flow in the same direction as the air flow by the first impeller. A second impeller to be generated;
A second motor section for rotating the second impeller about the rotation center axis;
A cylindrical housing surrounding the first impeller and the second impeller in the radial direction;
Between the first impeller and the second impeller, a radial center is provided about the rotation center axis, and each outer tip is connected to the housing to support at least the first motor portion with respect to the housing. A plurality of supporting ribs,
With
Each of the support ribs is inclined and supported so that an end edge on the first impeller side in an arbitrary radial cross section is positioned upstream of an end edge on the second impeller side in the rotation direction of the first impeller. The rib has an inclined surface facing the first impeller side, and the direction of the air flow of the air generated by the first impeller of the first impeller is substantially parallel to the inclined surface;
The angle of the inclined surface with respect to the direction of the rotation center axis is substantially the same at the upper end portion and the lower end portion of the inclined surface,
The upper end and the lower end are connected by a flat surface or a smooth curved surface,
An in-line axial fan, wherein an inclination angle of an inclined surface of each support rib is formed so as to decrease from an inner side to an outer side in a radial direction perpendicular to the rotation center axis.

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