Axial blower

Abstract

To provide an axial blower capable of suppressing reduction in blowing efficiency.SOLUTION: An axial blower 1 is provided with: a cylindrical casing 3 having a hollow space 4 including a central axis P1 connecting an upstream side and a downstream side; a motor 5 having a rotation axis P2 parallel to the central axis P1 and rotating a fan 7 around the rotation axis P2 as a rotation center; and a motor stay part 10 having a placing table 11 on which the motor 5 is placed, and a support part 12 connected to the casing 3 at a casing connection part and connected to the placing table 11 at a placing table connection part to support the placing table 11 in the hollow space 4. The casing connection part includes: a casing connection part upstream end located on the upstream side; and a casing connection part downstream end located on the downstream side. A virtual line connecting the casing connection part upstream end and the casing connection part downstream end has a prescribed angle A with respect to the central axis P1.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an axial flow fan. [Background technology]

[0002] Axial flow fans are known as tunnel ventilation devices that have bidirectional operation and are installed near the ceiling of a tunnel to ventilate the tunnel by increasing the pressure caused by the jet of air. Axial flow fans are also used to control the direction and volume of airflow in a tunnel by operating in the opposite direction to the airflow in the tunnel.

[0003] Conventionally, as this type of axial flow fan, there is known one in which a motor stay that supports a motor is provided parallel to the central axis of a casing that is parallel to the longitudinal direction of the casing (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2000-257587 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, unlike axial flow fans installed in open spaces, axial flow fans installed inside tunnels have a special direction of air passing through the inside of the casing of the axial flow fan. Specifically, axial flow fans for tunnels are often installed not in the center of the tunnel, but near the side walls or ceiling of the tunnel, that is, at the 11 o'clock or 1 o'clock position in the cross-sectional view of the tunnel. Therefore, even if the influence of the fan is ignored, the air flow passing through the casing is greatly influenced by the tube shape of the tunnel, so it does not necessarily flow parallel to the central axis. Therefore, depending on the flow direction, the air flow may collide with the motor stay, causing airflow resistance. This causes a problem of reduced airflow efficiency.

[0006] The present invention has been made in view of the problems inherent in the conventional art, and an object of the present invention is to provide an axial flow fan capable of suppressing a decrease in blowing efficiency. [Means for solving the problem]

[0007] In order to solve the above problems, the axial flow fan of the present invention includes a cylindrical casing having a hollow space including a central axis connecting the upstream side and the downstream side, a motor having a rotation axis parallel to the central axis and rotating a fan around the rotation axis, a mounting base on which the motor is mounted, and a motor stay unit having a support part connected to the casing at a casing connection part and connected to the mounting base at a mounting base connection part for supporting the mounting base in the hollow space. The casing connection part includes an upstream end of the casing connection part located on the upstream side and a downstream end of the casing connection part located on the downstream side, and an imaginary line connecting the upstream end of the casing connection part and the downstream end of the casing connection part forms a predetermined angle A with the central axis. This achieves the intended object. Effect of the Invention

[0008] According to the present invention, it is possible to provide an axial flow fan capable of suppressing a decrease in blowing efficiency. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram showing the configuration of an axial flow fan according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a schematic diagram of the motor stay portion 10 according to the first embodiment of the present invention as viewed from the Z-axis direction. [Diagram 3] FIG. 3 is a schematic diagram of the motor stay portion 10 according to the first embodiment of the present invention as viewed from the Y-axis direction. [Figure 4] FIG. 4(a) is a partial cross-sectional view of the hub cone portion 40 and the hub stay portion 41 as viewed from the Y-axis direction, and FIG. 4(b) is a perspective view of the hub cone portion 40 and the hub stay portion 41 as viewed from the downstream direction. [Diagram 5] 5(a) is a vertical cross-sectional view of the axial flow fan 1 in the vicinity of the motor stay portion 10, and FIG. 5(b) is a cylindrical cross-sectional view of the axial flow fan 1 showing the airflow in the vicinity of the motor stay portion 10. [Figure 6] 6(a) is a vertical cross-sectional view of the axial flow fan 1 in the vicinity of the hub stay portion 41, and FIG. 6(b) is a cylindrical cross-sectional view of the axial flow fan 1 showing the airflow in the vicinity of the hub stay portion 41. As shown in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an axial flow fan according to an embodiment will be described with reference to the drawings. Note that the dimensional ratios in the drawings are exaggerated for convenience of explanation and may differ from the actual ratios. The X-axis and the Y-axis are axes that are perpendicular to each other on a horizontal plane. The Z-axis is an axis perpendicular to the horizontal plane. On the Z-axis, the positive direction represents a vertical upward direction, and the negative direction represents a vertical downward direction.

[0011] [Embodiment 1] First, an overview of an axial flow fan according to the present embodiment will be described with reference to Fig. 1. Fig. 1 is a schematic diagram for explaining an axial flow fan 1 according to the present embodiment.

[0012] The axial flow fan 1 is a ventilation device that is installed in a tunnel for automobiles to expel harmful substances such as smoke, carbon monoxide, and nitrogen oxides emitted from automobiles from the tunnel and send fresh air into the tunnel. As shown in Fig. 1, the axial flow fan 1 is equipped with a fan 7 that can rotate in both forward and reverse directions to blow air in both the forward V direction and the reverse W direction. For example, if the V direction is the forward direction (forward direction), the W direction is the reverse direction. This makes it possible to switch the blowing direction according to changes in the traffic volume of automobiles passing through the tunnel, the direction of natural wind, or a fire that breaks out inside the tunnel.

[0013] 1, the axial flow fan 1 includes a casing 3, a motor 5, a fan 7, a motor stay portion 10, a hub cone portion 40, and a hub stay portion 41. The following description will be given assuming that the axial flow fan 1 blows air in the V direction. Note that the description of the case where the axial flow fan 1 blows air in the W direction will be omitted because the fan is rotated in the reverse direction to achieve the same corresponding relationship as the case where the axial flow fan 1 blows air in the V direction.

[0014] (Casing) The casing 3 is a cylindrical structure having a hollow space 4, and the openings at both ends are cylindrical or rectangular. In this embodiment, the case where the casing 3 is cylindrical will be described. The casing 3 is hung near the ceiling of the tunnel using mounting brackets. The casing 3 is also configured to have a sound-absorbing part therein, which is made of sound-absorbing material, a perforated plate, etc. The central axis P1 of the casing 3, i.e., the central axis P1 of the hollow space 4, is parallel to the rotation axis P2 of the motor 5, which will be described later.

[0015] (motor) The motor 5 is installed in the hollow space 4 by a motor stay portion 10 described later. In particular, the motor 5 is preferably installed so that the distance from the upstream opening and the distance from the downstream opening of the casing 3 are equal. In addition, the motor 5 is preferably installed near the center of the casing 3 in the inner diameter direction.

[0016] The motor 5 has a rotation axis P2. The rotation axis P2 of the motor 5 is connected to the fan 7, and the motor 5 has a function of rotating the fan 7 around the rotation axis P2 as a rotation center and reversing the rotation direction. For example, the motor 5 may rotate the fan 7 clockwise or counterclockwise. In this embodiment, a case will be described in which the motor 5 rotates the fan 7 counterclockwise when viewed from the upstream side when the air blowing direction is the V direction. The rotation axis P2 is parallel to the central axis P1 of the casing 3. That is, in this embodiment, the rotation axis P2 coincides with the central axis P1.

[0017] (fan) The fan 7 is connected to the rotation axis P2, i.e., the motor 5, and rotates by the motor 5 to generate an airflow in the hollow space 4. The fans 7 are connected to both the upstream and downstream sides of the motor 5. In other words, since there are two fans 7 installed around the motor 5, even when the airflow direction is switched between forward and reverse, an airflow can be generated with the same volume of air as before the switching. The fan 7 includes a base 8 and a plurality of blades 9.

[0018] The base 8 is cylindrical, and has a plurality of blades 9 attached at equal intervals in the circumferential direction. The base 8 is adjacent to the motor 5, and is connected to the rotation shaft P2.

[0019] For example, six blades 9 are attached to base 8, and the cross section of blade 9 is an axisymmetric airfoil shape. The number of blades 9 may be any number as long as it is more than one, and may be, for example, three to five. The cross section of blade 9 may also be an asymmetric airfoil shape.

[0020] (Motor stay part) The motor stay portion 10 will be described with reference to Fig. 2 and Fig. 3. Fig. 2 is a schematic diagram of the motor stay portion 10 as viewed from the Z-axis direction. Fig. 3 is a schematic diagram of the motor stay portion 10 as viewed from the Y-axis direction. Note that in Fig. 2, a central support portion 34, which will be described later, is indicated by a dotted line, and a central axis P1 (two-dot chain line) is overlapped thereon.

[0021] The motor stay portion 10 is a member that holds the motor 5 in the hollow space 4. The motor stay portion 10 is provided at the center in the X-axis direction of the hollow space 4 and below in the Z-axis direction (see FIG. 5(b)). The motor stay portion 10 includes a mounting base 11 and a support portion 12.

[0022] ((Placement table)) The mounting table 11 is a member on which the motor 5 is mounted, and is a plate-like member having a substantially parallelogram shape. The mounting table 11 has a surface including a mounting table upstream side 11a, a mounting table downstream side 11b, a mounting table right side 11c, and a mounting table left side 11d.

[0023] The upstream side 11a of the mounting table is the side located on the upstream side among the sides constituting the mounting table 11, and is the side facing the downstream side 11b of the mounting table. The upstream side 11a of the mounting table is provided perpendicular to the central axis P1. In other words, the upstream side 11a of the mounting table is provided parallel to the Y axis of the casing 3.

[0024] The downstream side 11b of the mounting table is a side located on the downstream side among the sides constituting the mounting table 11, and faces the upstream side 11a of the mounting table. The downstream side 11b of the mounting table is provided perpendicular to the central axis P1. In other words, the downstream side 11b of the mounting table is provided parallel to the Y axis of the casing 3.

[0025] The right side 11c of the mounting table 11 is the side located on the right side when viewed from the upstream side, and is the side opposite to the left side 11d of the mounting table. The predetermined angle A is provided with respect to the target object. The predetermined angle will be described later.

[0026] The mounting table left side 11d is the side located on the left side when viewed from the upstream side, among the sides constituting the mounting table 11, and is the side opposite to the mounting table right side 11c. The mounting table left side 11d is provided at a predetermined angle A with respect to the central axis P1.

[0027] That is, in the mounting table 11, the angle between the mounting table upstream side 11a and the mounting table left side 11d, and the angle between the mounting table downstream side 11b and the mounting table right side 11c are the predetermined angle A. Note that the predetermined angle A is an acute angle.

[0028] ((Support part)) The support portion 12 is a member that supports the mounting table 11 in the hollow space 4 .

[0029] The support portion 12 is connected to the casing 3 at a casing connection portion 55. The casing connection portion 55 includes a casing connection portion upstream end 55a located on the upstream side and a casing connection portion downstream end 55b located on the downstream side.

[0030] The support portion 12 is connected to the mounting table 11 at a mounting table connection portion 56. The mounting table connection portion 56 includes a mounting table connection portion upstream end 56a located on the upstream side and a mounting table connection portion downstream end 56b located on the downstream side.

[0031] The support portion 12 has an upstream end 57 located on the upstream side and having a casing connection portion upstream end 55a and a mounting table connection portion upstream end 56a. The support portion 12 has a downstream end 58 located on the downstream side and having a casing connection portion downstream end 55b and a mounting table connection portion downstream end 56b. The support portion 12 has an outer support portion 13 and a central support portion 34.

[0032] (((outer support part))) The outer support part 13 is connected to the right or left side of the mounting table 11, and supports the mounting table 11 in the hollow space 4. The outer support part 13 has a right outer support part 14 and a left outer support part 24. The mounting table 11, the right outer support part 14, and the left outer support part 24 have an integral structure and are formed by bending a single plate-like member.

[0033] The right outer support part 14 is connected to the right side 11c of the mounting table and supports the mounting table 11 in the hollow space 4. The right outer support part 14 is provided with a right outer casing connection part 15 as a casing connection part, and a right outer mounting table connection part 16 as a mounting table connection part.

[0034] The right outer casing connection part 15 is a part that is connected to the casing 3, and constitutes one side of the right outer support part 14. The upstream end of the right outer casing connection part 15 is the right outer casing connection part upstream end 15a, and the downstream end is the right outer casing connection part downstream end 15b. The right outer casing connection part 15 faces the right outer mounting table connection part 16.

[0035] A virtual line G connecting the right outer casing connection upstream end 15a and the right outer casing connection downstream end 15b has a predetermined angle A with respect to the central axis P1. The right outer casing connection 15 having the right outer casing connection upstream end 15a and the right outer casing connection downstream end 15b has a predetermined angle A with respect to the central axis P1. When the upstream opening of the casing 3 is viewed from the front in the downstream opening direction, the right outer casing connection upstream end 15a is located on the left side of the right outer casing connection downstream end 15b. The predetermined angle A will be described later. The virtual line G and the right outer casing connection 15 are provided along the flow direction of the airflow when the airflow, which flows at a predetermined angle A with respect to the length direction of the central axis P1 due to the rotation of the fan 7, passes through the motor stay portion 10. For convenience of illustration, the virtual line G in FIG. 2 is not drawn. is depicted adjacent to the right outer casing connection part 15 using a dashed dotted line, but in reality the right outer casing connection part 15 is located on imaginary line G. The same applies to each of the subsequent imaginary lines and each side of the motor stay part 10 corresponding to each imaginary line.

[0036] The right outer mounting table connection part 16 is a part that connects to the right side 11c of the mounting table, and constitutes one side of the right outer support part 14. The upstream end of the right outer mounting table connection part 16 is the right outer mounting table connection part upstream end 16a, and the downstream end is the right outer mounting table connection part downstream end 16b. The right outer mounting table connection part 16 faces the right outer casing connection part 15.

[0037] A virtual line H connecting the right outer mounting table connection upstream end 16a and the right outer mounting table connection downstream end 16b has a predetermined angle A with respect to the central axis P1. The right outer mounting table connection 16 having the right outer mounting table connection upstream end 16a and the right outer mounting table connection downstream end 16b has a predetermined angle A with respect to the central axis P1. When the upstream opening of the casing 3 is viewed from the front in the downstream opening direction, the right outer mounting table connection upstream end 16a is located on the left side of the right outer mounting table connection downstream end 16b. The virtual line H and the left outer mounting table connection 26 are provided along the flow direction of the airflow when the airflow passes through the motor stay part 10, the airflow flowing at a predetermined angle A with respect to the length direction of the central axis P1 due to the rotation of the fan 7. In other words, the angle A is the angle between the flow direction of the airflow when passing through the motor stay part 10 and the central axis P1.

[0038] The right outer casing connection portion 15 and the right outer mounting table connection portion 16 are connected by a right outer upstream end edge 17 and a right outer downstream end edge 18 .

[0039] The right outer upstream end edge 17 has at one end the right outer casing connection part upstream end 15a and at the end opposite the one end the right outer mounting table connection part upstream end 16a, and is the side located on the upstream side of the right outer support part 14. The right outer upstream end edge 17 is connected to the casing 3 by the right outer casing connection part upstream end 15a, and is connected to the mounting table 11 by the right outer mounting table connection part upstream end 16a. The right outer upstream end edge 17 faces the right outer downstream end edge 18.

[0040] The right outer downstream end edge 18 has at one end the right outer casing connection part downstream end 15b and at the end opposite the one end the right outer mounting table connection part downstream end 16b, and is the side located on the downstream side of the right outer support part 14. The right outer downstream end edge 18 is connected to the casing 3 by the right outer casing connection part downstream end 15b, and is connected to the mounting table 11 by the right outer mounting table connection part downstream end 16b. The right outer downstream end edge 18 faces the right outer upstream end edge 17.

[0041] That is, the right outer support portion 14 has a right outer flow straightening surface 19 formed by the right outer casing connection portion 15, the right outer mounting table connection portion 16, the right outer upstream end edge 17, and the right outer downstream end edge 18.

[0042] The right outer straightening surface 19 is a surface having a predetermined angle A with respect to the central axis P1, and is provided to suppress the occurrence of turbulence in the airflow passing near the right outer straightening surface 19 and to allow the airflow to flow in one direction. For example, the right outer straightening surface 19 is preferably of a plate-like structure rather than a structure with holes in the surface or a mesh-like structure. The right outer straightening surface 19 is provided along the flow direction of the airflow when the airflow, which flows at a predetermined angle A with respect to the longitudinal direction of the central axis P1 due to the rotation of the fan 7, passes through the motor stay portion 10.

[0043] The lengths of the sides of the right outer flow straightening surface 19 are not uniform. For example, the length of the right outer casing connection portion 15 is shorter than the length of the right outer mounting base connection portion 16. In other words, the right outer casing connection portion upstream end 15a is located downstream of the right outer mounting base connection portion upstream end 16a, and the right outer casing connection portion downstream end 15b is located upstream of the right outer mounting base connection portion downstream end 16b. In other words, the right outer flow straightening surface 19 has a shape that tapers from the right outer mounting table connection portion 16 toward the right outer casing connection portion 15.

[0044] When the motor stay portion 10 is viewed from the side in the Y-axis direction, the right outer casing connection portion 15 is preferably located near the center in the X-axis direction of the right outer mounting base connection portion 16. For example, a point on the right outer mounting base connection portion 16 that has the same X-axis component as the right outer casing connection portion upstream end 15a is defined as point T, and a point on the right outer mounting base connection portion 16 that has the same X-axis component as the right outer casing connection portion downstream end 15b is defined as point U. Here, it is preferable that the distance R from the right outer mounting base connection portion upstream end 16a to point T and the distance S from the right outer mounting base connection portion downstream end 16b to point U are approximately the same.

[0045] The left outer support part 24 is connected to the left side 11d of the mounting table, and supports the mounting table 11 in the hollow space 4. The left outer support part 24 is provided with a left outer casing connection part 25 as a casing connection part, and a left outer mounting table connection part 26 as a mounting table connection part.

[0046] The left outer casing connection part 25 is a part that is connected to the casing 3, and constitutes one side of the left outer support part 24. The upstream end of the left outer casing connection part 25 is the left outer casing connection part upstream end 25a, and the downstream end is the left outer casing connection part downstream end 25b. The left outer casing connection part 25 faces the left outer mounting table connection part 26.

[0047] An imaginary line I connecting the left outer casing connection portion upstream end 25a and the left outer casing connection portion downstream end 25b has a predetermined angle A with respect to the central axis P1. The left outer casing connection portion 25 having the left outer casing connection portion upstream end 25a and the left outer casing connection portion downstream end 25b has a predetermined angle A with respect to the central axis P1. When the upstream opening of the casing 3 is viewed from the front in the downstream opening direction, the left outer casing connection portion upstream end 25a is located on the left side of the left outer casing connection portion downstream end 25b. The imaginary line I and the left outer casing connection portion 25 are provided along the flow direction of the airflow when the airflow, which flows at the predetermined angle A with respect to the length direction of the central axis P1 due to the rotation of the fan 7, passes through the motor stay portion 10.

[0048] The left outer mounting table connection part 26 is a part that connects to the mounting table left side 11d, and constitutes one side of the left outer support part 24. The upstream end of the left outer mounting table connection part 26 is the left outer mounting table connection part upstream end 26a, and the downstream end is the left outer mounting table connection part downstream end 26b. The left outer mounting table connection part 26 faces the left outer casing connection part 25.

[0049] An imaginary line J connecting the left outer mounting table connection upstream end 26a and the left outer mounting table connection downstream end 26b has a predetermined angle A with respect to the central axis P1. The left outer mounting table connection 26 having the left outer mounting table connection upstream end 26a and the left outer mounting table connection downstream end 26b has a predetermined angle A with respect to the central axis P1. When the upstream opening of the casing 3 is viewed from the front in the downstream opening direction, the left outer mounting table connection upstream end 26a is located on the left side of the left outer mounting table connection downstream end 26b. The imaginary line J and the left outer mounting table connection 26 are provided along the flow direction of the airflow when the airflow flows at the predetermined angle A with respect to the length direction of the central axis P1 due to the rotation of the fan 7 and passes through the motor stay part 10.

[0050] The left outer casing connection portion 25 and the left outer mounting table connection portion 26 are connected by a left outer upstream end edge 27 and a left outer downstream end edge 28 .

[0051] The left outer upstream end edge 27 has the left outer casing connection portion upstream end 25a at one end and the left outer mounting base connection portion upstream end 26a at the opposite end, and is the side located on the upstream side of the left outer support portion 24. The left outer upstream end 27 faces the left outer downstream end 28. The left outer upstream end 27 faces the left outer downstream end 28. The left outer upstream end 27 faces the left outer downstream end 28. The left outer upstream end 27 faces the left outer downstream end 28. The left outer upstream end 27 faces the left outer downstream end 28. The left outer downstream end 28 ...

[0052] The left outer downstream end edge 28 has at one end the left outer casing connection portion downstream end 25b and at the end opposite the one end the left outer mounting table connection portion downstream end 26b, and is the downstream side edge of the left outer support portion 24. The left outer downstream end edge 28 is connected to the casing 3 by the left outer casing connection portion downstream end 25b, and is connected to the mounting table 11 by the left outer mounting table connection portion downstream end 26b. The left outer downstream end edge 28 faces the left outer upstream end edge 27.

[0053] That is, the left outer support portion 24 has a left outer flow straightening surface 29 formed with the left outer casing connection portion 25, the left outer mounting table connection portion 26, the left outer upstream end edge 27, and the left outer downstream end edge 28 as its sides.

[0054] The left outer rectifying surface 29 is a surface having a predetermined angle A with respect to the central axis P1, and is provided to suppress the generation of turbulence in the airflow passing near the left outer rectifying surface 29 and to allow the airflow to flow in one direction. For example, the left outer rectifying surface 29 is preferably of a plate-like structure rather than a structure having holes in the surface or a mesh-like structure. The left outer rectifying surface 29 is provided along the flow direction of the airflow when the airflow, which flows at a predetermined angle A with respect to the longitudinal direction of the central axis P1 due to the rotation of the fan 7, passes through the motor stay portion 10.

[0055] The lengths of each side of the left outer flow straightening surface 29 are not uniform. For example, the length of the left outer casing connection portion 25 is shorter than the length of the left outer mounting table connection portion 26. In other words, the left outer casing connection portion upstream end 25a is located downstream of the left outer mounting table connection portion upstream end 26a, and the left outer casing connection portion downstream end 25b is located upstream of the left outer mounting table connection portion downstream end 26b. In other words, the left outer flow straightening surface 29 has a shape that tapers from the left outer mounting table connection portion 26 toward the left outer casing connection portion 25.

[0056] When the motor stay portion 10 is viewed from the side in the Y-axis direction, the left outer casing connection portion 25 is preferably located near the center in the X-axis direction of the left outer mounting table connection portion 26. For example, a point on the left outer mounting table connection portion 26 that has the same X-axis component as the left outer casing connection portion upstream end 25a is defined as point U', and a point on the left outer mounting table connection portion 26 that has the same X-axis component as the left outer casing connection portion downstream end 25b is defined as point T'. Here, it is preferable that the distance S' from the left outer mounting table connection portion upstream end 26a to point U' and the distance R' from the left outer mounting table connection portion downstream end 26b to point T' are substantially the same.

[0057] It is preferable that the distance R at the right outer mounting table connection portion 16 and the distance R' at the left outer mounting table connection portion 26 are substantially the same. It is also preferable that the distance S at the right outer mounting table connection portion 16 and the distance S' at the left outer mounting table connection portion 26 are substantially the same.

[0058] Moreover, the right outer flow straightening surface 19 and the left outer flow straightening surface 29 have the same shape. More specifically, the shapes satisfy the following conditions. First, the mounting base 11 is a parallelogram, and the length of the right outer mounting base connection portion 16 and the length of the left outer mounting base connection portion 26 are equal. Second, the length of the right outer casing connection portion 15 and the length of the left outer casing connection portion 25 are equal. Furthermore, the length of the right outer downstream end edge 18 and the length of the left outer upstream end edge 27 are equal. Finally, the length of the right outer upstream end edge 17 and the length of the left outer downstream end edge 28 are equal. It is preferable that the right outer flow straightening surface 19 and the left outer flow straightening surface 29 have shapes that satisfy the above conditions.

[0059] (((Central support))) The central support portion 34 is connected to the mounting table 11 on the opposite side of the surface of the mounting table 11 on which the motor 5 is mounted, and supports the mounting table 11 in the hollow space 4. The central support portion 34 is, for example, a square. The shape is a rectangle including

[0060] The central support portion 34 includes a central casing connection portion 35 as a casing connection portion, and a central mounting table connection portion 36 as a mounting table connection portion.

[0061] The central casing connection part 35 is a part that connects to the casing 3, and constitutes one side of the central support part 34. The upstream end of the central casing connection part 35 is the central casing connection part upstream end 35a, and the downstream end is the central casing connection part downstream end 35b. The central casing connection part 35 faces the central mounting table connection part 36.

[0062] A virtual line K connecting the central casing connection portion upstream end 35a and the central casing connection portion downstream end 35b has a predetermined angle A with respect to the central axis P1. The central casing connection portion 35 having the central casing connection portion upstream end 35a and the central casing connection portion downstream end 35b has a predetermined angle A with respect to the central axis P1. When the upstream opening of the casing 3 is viewed from the front in the downstream opening direction, the central casing connection portion upstream end 35a is located on the left side of the central casing connection portion downstream end 35b. The virtual line K and the central casing connection portion 35 are provided along the flow direction of the airflow when the airflow flows at a predetermined angle A with respect to the length direction of the central axis P1 due to the rotation of the fan 7 and passes through the motor stay portion 10.

[0063] The central mounting table connection part 36 is a part that connects to the mounting table 11, and constitutes one side of the central support part 34. The upstream end of the central mounting table connection part 36 is the central mounting table connection part upstream end 36a, and the downstream end of the central mounting table connection part 36 is the central mounting table connection part downstream end 36b. The central mounting table connection part 36 faces the central casing connection part 35.

[0064] A virtual line L connecting the central mounting table connection portion upstream end 36a and the central mounting table connection portion downstream end 36b has a predetermined angle A with respect to the central axis P1. The central mounting table connection portion 36 having the central mounting table connection portion upstream end 36a and the central mounting table connection portion downstream end 36b has a predetermined angle A with respect to the central axis P1. When the upstream opening of the casing 3 is viewed from the front in the downstream opening direction, the central mounting table connection portion upstream end 36a is located on the left side of the central mounting table connection portion downstream end 36b. The virtual line L and the central mounting table connection portion 36 are provided along the flow direction of the airflow when the airflow flows at a predetermined angle A with respect to the length direction of the central axis P1 due to the rotation of the fan 7 and passes through the motor stay portion 10.

[0065] The central casing connection portion 35 and the central mounting table connection portion 36 are connected by a central upstream end edge 37 and a central downstream end edge 38 .

[0066] The central upstream end edge 37 has a central casing connection part upstream end 35a at one end and a central mounting table connection part upstream end 36a at the end opposite the one end, and is the side located on the upstream side of the central support part 34. The central upstream end edge 37 is connected to the casing 3 by the central casing connection part upstream end 35a, and is connected to the mounting table 11 by the central mounting table connection part upstream end 36a. The central upstream end edge 37 faces the central downstream end edge 38.

[0067] The central downstream end edge 38 has central casing connection part downstream end 35b at one end and central mounting table connection part downstream end 36b at the end opposite to the one end, and is the side located on the downstream side of the central support part 34. The central downstream end edge 38 is connected to the casing 3 by the central casing connection part downstream end 35b, and is connected to the mounting table 11 by the central mounting table connection part downstream end 36b. The central downstream end edge 38 faces the central upstream end edge 37.

[0068] That is, the central support portion 34 has a central flow straightening surface 39 formed with the central casing connection portion 35, the central mounting table connection portion 36, the central upstream end edge 37, and the central downstream end edge 38 as its sides.

[0069] The central straightening surface 39 is a surface having a predetermined angle A with respect to the central axis P1, and is provided to suppress the occurrence of turbulence in the airflow passing near the central straightening surface 39 and to allow the airflow to flow in one direction. For example, the central straightening surface 39 is preferably of a plate-like structure rather than a structure having holes in the surface or a mesh-like structure. The central straightening surface 39 is provided along the flow direction of the airflow when the airflow, which flows at a predetermined angle A with respect to the longitudinal direction of the central axis P1 due to the rotation of the fan 7, passes through the motor stay portion 10.

[0070] It is preferable that the distance D of the central support portion 34 from the right side of the mounting table and the distance E from the left side of the mounting table are substantially the same.

[0071] It is preferable that the length M of the central support portion 34 in the X-axis direction be shorter than the length N between the mounting table upstream side 11a and the mounting table downstream side 11b in the X-axis direction.

[0072] Next, the hub cone portion 40 and the hub stay portion 41 will be described with reference to Fig. 4. Fig. 4(a) is a schematic diagram of the hub cone portion 40 and the hub stay portion 41 as viewed from the Y-axis direction, and Fig. 4(b) is a perspective view of the hub cone portion 40 and the hub stay portion 41 as viewed from the downstream direction.

[0073] (Hub cone part) The hub cone portion 40 is located downstream of the fan 7, and is supported by the hub stay portion 41 described below. In other words, the hub cone portion 40 is provided outward of the motor stay portion in the longitudinal direction of the central axis P1. The hub cone portion 40 has a hemispherical shape, and is attached to the downstream side of the motor 5 in the direction of the central axis P1 at a position adjacent to the fan 7. The hub cone portion 40 has an internal sound-absorbing portion formed of a sound-absorbing material, a perforated plate, etc. The hub cone portion 40 may be substantially conical in shape. The hub cone portion 40 has an outer diameter smaller than that of the motor 5.

[0074] (Hub stay section) The hub stay portion 41 is a member that supports the hub cone portion 40 within the hollow space 4. Four hub stay portions 41 are provided at equal intervals in the circumferential direction from the hub cone portion 40 in a cross section parallel to the YZ plane.

[0075] The hub stay portion 41 is connected to the casing 3 at a hub casing connection portion 45 , and is connected to the hub cone portion 40 at a hub cone connection portion 46 .

[0076] The hub casing connecting portion 45 has a hub casing connecting portion upstream end 45a located on the upstream side and a hub casing connecting portion downstream end 45b located on the downstream side.

[0077] The hub-cone connecting portion 46 has an upstream end 46a of the hub-cone connecting portion located on the upstream side and a downstream end 46b of the hub-cone connecting portion located on the downstream side.

[0078] The hub stay portion 41 includes a hub upstream end side 47 located on the upstream side and having a hub casing connection portion upstream end 45a and a hub cone connection portion upstream end 46a. The hub stay portion 41 includes a hub downstream end side 48 located on the downstream side and having a hub casing connection portion downstream end 45b and a hub cone connection portion downstream end 46b.

[0079] Hub casing connection portion 45 is a portion that connects to the casing 3, and constitutes one side of the hub stay portion 41. The upstream end of hub casing connection portion 45 is hub casing connection portion upstream end 45a, and the downstream end is hub casing connection portion downstream end 45b. Hub casing connection portion 45 faces hub cone connection portion 46.

[0080] An imaginary line connecting the hub casing connection portion upstream end 45a and the hub casing connection portion downstream end 45b forms a predetermined angle B with respect to the central axis P1. The hub casing connection portion 45, which has the hub casing connection portion upstream end 45a and the hub casing connection portion downstream end 45b, forms a predetermined angle B with respect to the central axis P1. When the upstream opening of the casing 3 is viewed from the front in the downstream opening direction, the hub casing connection portion upstream end 45a is located on the left side of the hub casing connection portion downstream end 45b. The predetermined angle B will be described later. The imaginary line and the hub casing connection portion 45 are provided along the flow direction of the airflow when the airflow, which flows at the predetermined angle B with respect to the length direction of the central axis P1 due to the rotation of the fan 7, passes through the hub stay portion 41.

[0081] Hub-cone connection portion 46 is a portion that connects to hub-cone portion 40, and constitutes one side of hub stay portion 41. The upstream end of hub-cone connection portion 46 is hub-cone connection portion upstream end 46a, and the downstream end is hub-cone connection portion downstream end 46b. Hub-cone connection portion 46 faces hub casing connection portion 45.

[0082] An imaginary line connecting the hub-cone connection portion upstream end 46a and the hub-cone connection portion downstream end 46b forms a predetermined angle B with respect to the central axis P1. Furthermore, the hub-cone connection portion 46, which has the hub-cone connection portion upstream end 46a and the hub-cone connection portion downstream end 46b, forms a predetermined angle B with respect to the central axis P1. When the upstream opening of the casing 3 is viewed from the front in the direction of the downstream opening, the hub-cone connection portion upstream end 46a is located on the left side of the hub-cone connection portion downstream end 46b. The imaginary line and the hub-cone connection portion 46 are provided along the flow direction of the airflow when the airflow, which flows at the predetermined angle B with respect to the length direction of the central axis P1 due to the rotation of the fan 7, passes through the hub stay portion 41.

[0083] The hub casing connection portion 45 and the hub cone connection portion 46 are connected by a hub upstream end edge 47 and a hub downstream end edge 48 .

[0084] Hub upstream end edge 47 has hub casing connection portion upstream end 45a at one end and hub cone connection portion upstream end 46a at the end opposite the one end, and is the side located on the upstream side of hub stay portion 41. Hub upstream end edge 47 is connected to casing 3 by hub casing connection portion upstream end 45a, and is connected to hub cone portion 40 by hub cone connection portion upstream end 46a. Hub upstream end edge 47 faces hub downstream end edge 48.

[0085] Here, the following description focuses on the hub stay portion 41 that is located at the uppermost position in the hollow space 4 in FIG. 4(a) among the four hub stay portions 41. The hub upstream end side 47 is preferably not arranged parallel to the YZ plane, but is arranged so as to form an angle C with a straight line F that includes the upstream end 46a of the hub cone connection portion and is parallel to the Z axis. Here, the angle C is preferably 20° to 40°, and more preferably 30°. In other words, it is preferable that the hub cone connection portion 46 of the hub stay portion 41 that is close to the center of the hollow space 4 is located upstream of the hub casing connection portion 45 that is close to the outer periphery of the hollow space 4. The angle C is an acute angle.

[0086] Hub downstream end edge 48 has hub casing connection portion downstream end 45b at one end and hub cone connection portion downstream end 46b at the end opposite the one end, and is the side located on the downstream side of the hub stay portion 41. Hub downstream end edge 48 is connected to the casing 3 by the hub casing connection portion downstream end 45b, and is connected to the hub cone portion 40 by the hub cone connection portion downstream end 46b. Hub downstream end edge 48 faces hub upstream end edge 47.

[0087] That is, the hub stay portion 41 includes a hub casing connection portion 45, a hub cone connection portion 46, and a hub casing connection portion 47. The hub has a hub flow straightening surface 49 formed with the hub upstream end edge 47 and the hub downstream end edge 48 as edges.

[0088] Hub straightening surface 49 is a surface that has a predetermined angle B with respect to central axis P1, and is provided to suppress the generation of turbulence in the airflow passing near hub straightening surface 49 and to allow the airflow to flow in one direction. For example, a plate-like structure is preferable for hub straightening surface 49, rather than a structure with holes in the surface or a mesh-like structure.

[0089] (angle) The predetermined angle A is preferably 5° to 14°, and more preferably 10°.

[0090] The predetermined angle B is preferably 15° to 25°, and more preferably 20°.

[0091] It is preferable that the predetermined angle A is smaller than the predetermined angle B within the above range. This is because the nature of the airflow near the hub stay portion 41 is different from that near the motor stay portion 10. The details will be described below. The outer diameter of the hub cone portion 40 is smaller than that of the motor 5. Therefore, the flow passage area through which the airflow can pass in the casing 3 is large near the hub cone portion 40, so the swirling component of the airflow is strong and the passing airflow becomes a swirling flow. On the other hand, the flow passage area is small near the motor stay portion 10, so the swirling component of the airflow is weak and the airflow passes near the motor stay portion 10 more linearly than near the hub cone portion 40. Therefore, in accordance with the nature of the passing airflow, the hub stay portion 41 and the motor stay portion 10 are provided so that the angle with respect to the central axis P1 is larger at the hub cone portion 40 where a swirling flow occurs than at the motor stay portion 10 where a linear flow is likely to occur.

[0092] As described above, the predetermined angle A and the predetermined angle B are both acute angles.

[0093] The above is the configuration of the axial flow fan 1.

[0094] Next, the operation of the axial flow fan 1 will be described.

[0095] In this embodiment, when the motor 5 of the axial flow blower 1 is driven, the fan 7 rotates counterclockwise as viewed from the left opening of the casing 3. As the fan 7 rotates, air is sucked in through the opening of the casing 3 and expelled from the opening on the opposite side. In other words, the left opening of the casing 3 is the upstream side, and air is blown in the V direction, i.e., downstream. This allows harmful substances such as smoke, carbon monoxide, and nitrogen oxides from automobiles that fill the tunnel to be expelled, and fresh air to be sent in. In addition, harmful gases or smoke resulting from a fire or the like can be exhausted outside the tunnel.

[0096] In order to improve the airflow efficiency of the axial flow fan 1 during this series of operations, it is necessary to reduce the airflow resistance inside the casing 3. In this embodiment, the motor stay portion 10 has a predetermined angle A, and therefore, by using a mechanism described below, it is possible to reduce the airflow resistance compared to when the motor stay portion is provided parallel to the central axis P1. The airflow efficiency indicates how much of the motor's output power (axial power) is converted into work (air volume and static pressure).

[0097] With reference to Figures 5 and 6, the mechanism by which the blowing resistance in the axial flow fan 1 is reduced will be described. Figure 5(a) is a vertical cross-sectional view of the axial flow fan 1 in the vicinity of the motor stay portion 10, and Figure 5(b) is a cylindrical cross-sectional view of the axial flow fan 1 showing the airflow in the vicinity of the motor stay portion 10. Note that the cylindrical cross-section Q1 in Figure 5(a) is a cross-section along the side of a cylinder parallel to the central axis P1, that is, a cross-section along the side of a cylinder with the central axis P1 as its central axis, and shows a cross-section at a position on the casing 3 side where the flow velocity is generally high. Figure 5(b) shows the airflow in the V direction. 5(a) is a schematic diagram of vectors of airflow generated from blades 9 in accordance with rotation of fan 7 in cylindrical cross section Q1 shown in FIG. 5(a).

[0098] First, referring to FIG. 5, the flow of air currents in the vicinity of the motor stay portion 10 will be described. As shown in FIG. 5(a), the vector of the air currents generated from the blades 9 as the fan 7 rotates has a predetermined angle with respect to the central axis P1. In this embodiment, the right outer support portion 14, the left outer support portion 24, and the central support portion 34 have a predetermined angle A between the central axis P1 and a virtual line connecting the upstream end and the downstream end of each support portion. This predetermined angle A is an angle that is parallel to the vector shown in FIG. 5(a). In other words, the right outer support portion 14, the left outer support portion 24, and the central support portion 34 are provided parallel to the air currents generated as the fan 7 rotates and passing near the motor stay portion 10. This makes it possible to prevent the right outer support portion 14, the left outer support portion 24, and the central support portion 34 from interfering with the air currents passing near the motor stay portion 10, compared to a case in which the right outer support portion 14, the left outer support portion 24, and the central support portion 34 are provided parallel to the central axis P1. Therefore, the airflow resistance can be reduced and the airflow efficiency is improved.

[0099] Next, referring to Fig. 6, the airflow in the vicinity of the hub stay portion 41 will be described. Fig. 6(a) is a vertical cross-sectional view of the axial flow fan 1 in the vicinity of the hub stay portion 41, and Fig. 6(b) is a cylindrical cross-sectional view of the axial flow fan 1 showing the airflow in the vicinity of the hub stay portion 41. The cylindrical cross-section Q2 in Fig. 6(a) is a cross-section along the side of a cylinder parallel to the central axis P1, that is, the side of a cylinder whose central axis is the central axis P1, and shows a cross-section at a position on the casing 3 side where the flow velocity is generally high. Fig. 6(b) is a schematic diagram of the vector of the airflow generated from the blades 9 with the rotation of the fan 7 in the cylindrical cross-section Q2 shown in Fig. 6(a) in the V-direction airflow.

[0100] As shown in FIG. 6(a), the vector of the airflow generated from the blades 9 as the fan 7 rotates has a predetermined angle with respect to the central axis P1. In this embodiment, the hub casing connection portion 45 has a predetermined angle B between the central axis P1 and an imaginary line connecting the hub casing connection portion upstream end 45a and the hub casing connection portion downstream end 45b. This predetermined angle B is an angle that is parallel to the vector shown in FIG. 6(a). In other words, the hub casing connection portion 45 is provided parallel to the airflow that is generated as the fan 7 rotates and passes near the hub stay portion 41. This makes it possible to prevent the hub casing connection portion 45 from interfering with the airflow that passes near the hub casing connection portion 45, compared to a case in which the hub casing connection portion 45 is provided parallel to the central axis P1. This makes it possible to suppress the airflow resistance and improve the airflow efficiency.

[0101] As described above, according to the axial flow fan 1 according to the present embodiment, it is possible to obtain the following effects (1) to (6).

[0102] (1) Axial flow fan 1 includes a cylindrical casing 3 having a hollow space 4 including a central axis P1 connecting the upstream side and the downstream side, a motor 5 having a rotation axis P2 parallel to the central axis P1 and rotating a fan 7 about the rotation axis P2 as a rotation center, a mounting base 11 on which the motor 5 is mounted, and a motor stay unit 10 having a support unit 12 connected to the casing 3 at a casing connection unit and connected to the mounting base 11 at a mounting base connection unit to support the mounting base 11 in the hollow space 4. The casing connection unit includes a casing connection unit upstream end located on the upstream side and a casing connection unit downstream end located on the downstream side, and an imaginary line connecting the casing connection unit upstream end and the casing connection unit downstream end forms a predetermined angle A with respect to the central axis P1.

[0103] This allows the support part 12 to be installed at a predetermined angle A with respect to the central axis P1. Therefore, the support part 12 can be installed at an angle along the airflow passing near the motor stay part 10, and a decrease in air blowing efficiency due to an increase in ventilation resistance can be suppressed.

[0104] (2) In the axial flow fan 1, the support portion 12 includes an upstream end side located on the upstream side, a downstream end side located on the downstream side, and a straightening surface that connects the upstream end side and the downstream end side and has a predetermined angle A with respect to the central axis P1. As a result, the motor stay portion 10 is provided with a straightening surface that has the predetermined angle A with respect to the central axis P1. This makes it possible to suppress the occurrence of turbulence in the airflow near the motor stay portion 10. Therefore, by making the airflow flow in one direction, it is possible to suppress a decrease in blowing efficiency due to an increase in ventilation resistance.

[0105] (3) In the axial flow fan 1, the imaginary line is provided along the flow direction of the airflow when the airflow, which flows at a predetermined angle with respect to the longitudinal direction of the rotation axis P2 due to the rotation of the fan 7, passes through the motor stay portion 10. This allows the motor stay portion 10 to be provided along the flow direction of the airflow. Therefore, it is possible to suppress a decrease in blowing efficiency due to an increase in ventilation resistance.

[0106] (4) In the axial flow fan 1, the mounting base connection portion has an upstream end of the mounting base connection portion located on the upstream side, and a downstream end of the mounting base connection portion located on the downstream side. The downstream end of the casing connection portion is located upstream of the downstream end of the mounting base connection portion, and the upstream end of the casing connection portion is located downstream of the upstream end of the mounting base connection portion. This makes the overall length of the casing connection portion shorter than the mounting base connection portion, and reduces the area of ​​the flow straightening surface. This makes it possible to suppress the ventilation resistance of the airflow flowing near the motor stay portion 10, and to suppress a decrease in blowing efficiency.

[0107] (5) The axial flow blower 1 includes a hub cone portion 40 that is disposed outward of the motor stay portion 10 in the longitudinal direction of the central axis P1 and straightens the airflow in the hollow space, and a hub stay portion 41 that is connected to the casing 3 and supports the hub cone portion 40 in the hollow space 4. The hub stay portion 41 includes a hub upstream end edge 47 located on the upstream side, a hub downstream end edge 48 located on the downstream side, and a hub straightening surface 49 in which an imaginary line connecting the hub upstream end edge 47 and the hub downstream end edge 48 forms a predetermined angle B with respect to the central axis P1. This allows the hub stay portion 41 to be installed at the predetermined angle B with respect to the central axis P1. Therefore, the hub stay portion 41 can be installed at an angle along the airflow passing near the hub stay portion 41, and a decrease in blowing efficiency due to an increase in ventilation resistance can be suppressed.

[0108] (6) In axial flow blower 1, hub cone portion 40 has an outer diameter smaller than that of motor 5, and angle A is smaller than angle B. As a result, hub stay portion 41, which has a larger flow passage area than the vicinity of motor stay portion 10 and a stronger swirling component of the incoming airflow, can be installed at a larger angle with respect to central axis P1 than motor stay portion 10. Therefore, hub stay portion 41 can be installed at an angle that follows the airflow flowing near hub stay portion 41, and a decrease in blowing efficiency due to increased ventilation resistance can be suppressed.

[0109] The present invention has been described above based on the embodiments. These embodiments are merely examples, and it will be understood by those skilled in the art that various modifications are possible in the combination of the respective components, and that such modifications are also within the scope of the present invention.

[0110] In the first embodiment, the plate-like constituent body is the flow straightening surface, but this is not limited thereto. For example, even if the support portion 12 is composed of a plurality of columnar members provided on the same plane, the surface composed of the plurality of columnar members can be regarded as the flow straightening surface.

[0111] In the first embodiment, the mounting base 11, the right outer support portion 14, and the left outer support portion 24 are integrally formed by bending a single plate-like member, but this is not limited thereto. For example, the mounting base 11, the right outer support portion 14, and the left outer support portion 24 may be formed as separate members. The mounting base 11 and the right outer support part 14, and the mounting base 11 and the left outer support part 24 may be integrated by connecting them by welding or the like. In this way, processing can be made easier than bending a plate-shaped member. In the first embodiment, the upstream end side of the support part 12 having the upstream end of the casing connection part and the upstream end of the mounting base connection part is a straight line, but this is not limited to this. For example, the upstream end side may be a curve that curves toward the downstream end side and connects the upstream end of the casing connection part and the upstream end of the mounting base connection part. In other words, the upstream end side is a curve that is convex toward the downstream side. In this way, the area of ​​the support part 12 is reduced compared to when the upstream end side is a straight line, so that the blowing resistance of the air flow passing through the motor stay part 10 can be reduced.

[0112] In the first embodiment, the downstream end edge of the support part 12, which has the downstream end of the casing connection part and the downstream end of the mounting base connection part, is a straight line, but this is not limited thereto. For example, the downstream end edge may be a curve that curves toward the upstream end edge and connects the downstream end of the casing connection part and the downstream end of the mounting base connection part. In other words, the downstream end edge is a curve that is convex toward the upstream side. In this way, the area of ​​the support part 12 is reduced compared to when the downstream end edge is a straight line, and therefore the blowing resistance of the airflow passing through the motor stay part 10 can be reduced.

[0113] In the first embodiment, the central support portion 34 has a rectangular shape including a square, but is not limited thereto. For example, the length of the central casing connection portion 35 may be shorter than the length of the central mounting base connection portion 36. In other words, the central casing connection portion upstream end 35a may be located downstream of the central mounting base connection portion upstream end 36a, and the central casing connection portion downstream end 35b may be located upstream of the central mounting base connection portion downstream end 36b. In other words, the central support portion 34 may have a trapezoidal shape narrowing from the central mounting base connection portion 36 toward the central casing connection portion 35. In this way, the area of ​​the central support portion 34 is reduced compared to when the central support portion 34 has a rectangular shape, and therefore the blowing resistance of the airflow passing through the motor stay portion 10 can be reduced.

[0114] In the first embodiment, the right outer flow straightening surface 19, the left outer flow straightening surface 29, and the central flow straightening surface 39 each have a predetermined angle A with respect to the central axis P1, but this is not limited thereto. For example, the angle of the right outer flow straightening surface 19, the angle of the left outer flow straightening surface 29, and the angle of the central flow straightening surface 39 with respect to the central axis P1 may be different within a range of values ​​smaller than the angle B. Specifically, the angle of the right outer flow straightening surface 19 with respect to the central axis P1 may be 10°, the angle of the left outer flow straightening surface 29 may be 10°, and the angle of the central flow straightening surface 39 may be 14°, or the angle of the right outer flow straightening surface 19 with respect to the central axis P1 may be 7°, the angle of the left outer flow straightening surface 29 may be 14°, and the angle of the central flow straightening surface 39 may be 10°. In this way, the flow straightening surfaces can be provided in a state closer to the airflow passing near each flow straightening surface, so that the blowing resistance of the airflow passing through the motor stay portion 10 can be further reduced.

[0115] In the first embodiment, the hub cone portion 40 has a hemispherical shape, but this is not limiting. For example, a cylindrical portion may be provided in a shape that continues to the cross section of the hemispherical portion. Specifically, a cylindrical portion may be provided between the hemispherical portion and the fan 7. Even in this case, the hemispherical portion can provide a rectifying effect.

[0116] In the first embodiment, four hub stay portions 41 are provided, but this is not limited to the above. A plurality of hub stay portions 41 may be provided, and may be any number between three and eight, for example. Even in this case, the hub stay portions are provided at equal intervals in the circumferential direction from the hub cone portion 40. [Industrial Applicability]

[0117] The axial flow fan according to the present invention has a structure that suppresses a decrease in the blowing efficiency of the air flow passing through the casing. It has a structure and is useful as an axial flow blower. [Explanation of symbols]

[0118] 1 axial blower 3. Casing 4 Hollow space 5 Motor 7 Fan 8 base 9. Feather 10 Motor stay part 11 Placement table 11a Upstream side of the loading platform 11b Downstream side of the loading platform 11c Right side of the mounting table 11d Left side of the mounting table 12 Support part 13 Outer support part 14 Right outer support 15 Right outer casing connection 15a Right outer casing connection upstream end 15b Right outer casing connection downstream end 16 Right outer mounting table connection part 16a Right outer mounting table connection part upstream end 16b Downstream end of right outer mounting table connection part 17 Right outer upstream edge 18 Right outer downstream edge 19 Right outer rectifying surface 24 Left outer support 25 Left outer casing connection 25a Left outer casing connection upstream end 25b Downstream end of left outer casing connection 26 Left outer mounting table connection part 26a Left outer mounting table connection part upstream end 26b Left outer mounting table connection downstream end 27 Left outer upstream edge 28 Left outer downstream edge 29 Left outer rectifying surface 34 Central support part 35 Central casing connection 35a Central casing connection upstream end 35b downstream end of central casing connection 36 Central mounting table connection part 36a Upstream end of central mounting table connection 36b Downstream end of central mounting table connection part 37 Center upstream edge 38 Center downstream end 39 Central rectifying surface 40 Hub cone part 41 Hub stay section 45 Hub casing connection 45a Hub casing connection upstream end 45b Downstream end of hub casing connection 46 Hub cone connection 46a Hub cone connection upstream end 46b Downstream end of hub cone connection 47 Hub upstream end 48 Downstream end of hub 49 Hub fairing surface 55 Casing connection 55a Casing connection upstream end 55b Casing connection downstream end 56 Mounting table connection part 56a Upstream end of mounting table connection part 56b Downstream end of mounting table connection part 57 Upstream end 58 Downstream end P1 center axis P2 Rotational Axis Q1 Cylindrical section Q2 Cylindrical section A Angle B Angle C Angle

Claims

1. a cylindrical casing having a hollow space including a central axis connecting an upstream side and a downstream side; a motor having a rotation shaft parallel to the central axis and configured to rotate the fan around the rotation shaft; a motor stay portion including a mounting base on which the motor is mounted, and a support portion connected to the casing at a casing connection portion and connected to the mounting base at a mounting base connection portion to support the mounting base in the hollow space, The casing connection portion is an upstream end of a casing connection portion located on the upstream side; a downstream end of a casing connection portion located on the downstream side, an imaginary line connecting the upstream end of the casing connection portion and the downstream end of the casing connection portion has a predetermined angle A with respect to the central axis;

2. The support portion is An upstream end side located on the upstream side; A downstream end side located on the downstream side; 2. The axial flow fan according to claim 1, further comprising a straightening surface connecting said upstream end side and said downstream end side and having said predetermined angle A with respect to said central axis.

3. The virtual line is 2. The axial flow blower according to claim 1, wherein the fan is disposed along a direction of airflow when the airflow passes through the motor stay portion, the airflow flowing at a predetermined angle with respect to the longitudinal direction of the rotating shaft due to rotation of the fan.

4. The mounting table connection portion is an upstream end of a mounting table connection portion located on the upstream side; a downstream end of a mounting table connection portion located on the downstream side, The downstream end of the casing connection portion is a downstream end of the mounting table connection portion, The upstream end of the casing connection portion is The axial flow fan according to claim 2 , wherein the mounting base connection portion is located downstream of an upstream end of the mounting base connection portion.

5. a hub cone portion that is provided outward of the motor stay portion in the longitudinal direction of the central axis and straightens the airflow in the hollow space; a hub stay portion connected to the casing and supporting the hub cone portion in the hollow space, The hub stay portion is an upstream end of the hub located on the upstream side; A downstream end of the hub located on the downstream side; 2. The axial flow blower according to claim 1, further comprising a hub flow straightening surface, wherein an imaginary line connecting said hub upstream end edge and said hub downstream end edge forms a predetermined angle B with said central axis.

6. The hub cone portion has an outer diameter smaller than an outer diameter of the motor, 6. The axial flow fan according to claim 5, wherein the angle A is smaller than the angle B.

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