Axial blower

Abstract

To provide a technique for reducing a swirl component in a swirl flow.SOLUTION: The casing 100 has a first opening 112, a second opening 122, and a hollow space 130. The electric motor 200 is disposed in the hollow space 130. The axial fan 210 is attached to the rotating shaft 300 of the electric motor 200 and is rotatable. The first hub cone portion 220 is disposed closer to the first opening 112 than the axial fan 210 in the hollow space 130, and rectifies the flow of air including the swirling flow from the axial fan 210. The first stay portion 224 is fixed to the casing 100, and supports the first hub cone portion 220 in the hollow space 130. An imaginary line connecting the stay-portion first end and the stay-portion second end is inclined with respect to the rotation axis 300 so that at least a part of the air including the swirling flow from the axial fan 210 collides with the stay-portion side surface of the first stay portion 224.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an axial flow fan that generates an airflow by rotating a plurality of blades. [Background technology]

[0002] Axial flow fans (jet fans) are used for ventilation or smoke extraction inside tunnels. The axial flow fan comprises a cylindrical casing with openings at both ends, an electric motor inside the casing, an axial flow fan that is rotatable in both forward and reverse directions and attached to the rotating shaft of the electric motor, and a hub cone that straightens the air flow, including the swirling flow, from the axial flow fan. The axial flow fan has multiple blades attached radially. The rotation of the multiple blades generates an airflow (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2024-42734 Summary of the Invention [Problem to be solved by the invention]

[0004] When the axial fan in an axial flow fan rotates, a swirling flow is generated that moves in a spiral shape inside the casing. In the swirling flow, if the swirling component that rotates around the rotation axis becomes large, the forward axial component becomes small, and the ventilation capacity of the axial flow fan decreases. On the other hand, it is required to increase the ventilation capacity of an axial flow fan by increasing the thrust. In order to increase the ventilation capacity, it is necessary to reduce the swirling component.

[0005] The present disclosure has been made to solve the above-mentioned problems, and aims to provide a technique for reducing the swirling component in a swirling flow. [Means for solving the problem]

[0006] To solve the above problems, one embodiment of an axial flow fan according to the present disclosure includes a cylindrical casing having a first opening at a first end, a second opening at a second end opposite the first end, and a hollow space connecting the first opening and the second opening; an electric motor disposed in the hollow space; an axial flow fan rotatably attached to a rotating shaft of the electric motor; a hub cone portion disposed closer to the first opening than the axial flow fan in the hollow space and rectifying the airflow including the swirling flow from the axial flow fan; and a stay portion fixed to the casing and supporting the hub cone portion in the hollow space. The stay portion is a plate-shaped member and includes a stay portion first end located on the axial flow fan side, a stay portion second end located on the first opening side, and a stay portion side surface connecting the stay portion first end and the stay portion second end. An imaginary line connecting the stay portion first end and the stay portion second end of the stay portion side is inclined with respect to the rotation axis so that at least a portion of the air including the swirling flow from the axial flow fan collides with the stay portion side surface. [Effects of the Invention]

[0007] According to the present disclosure, the swirling component in the swirling flow can be reduced. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a cross-sectional perspective view showing the structure of an axial flow fan according to an embodiment. [Figure 2] FIG. 2 is a cross-sectional view showing the structure of the axial flow fan of FIG. [Figure 3] FIG. 3 is an enlarged view of the vicinity of the first stay portion in FIG. [Figure 4] FIG. 4 is an enlarged view of the vicinity of the stay portion for comparison. [Figure 5] FIG. 5 is an enlarged view of the vicinity of the stay portion for comparison. DETAILED DESCRIPTION OF THE INVENTION

[0009] An axial flow fan according to an embodiment will be described below with reference to the drawings. The dimensional proportions in the drawings have been exaggerated for the sake of explanation and may differ from the actual proportions. The x-axis and y-axis are axes that are perpendicular to each other on a horizontal plane, and the z-axis is an axis that is perpendicular to the horizontal plane. The positive direction of the x-axis is sometimes called the "front side," the negative direction of the x-axis is sometimes called the "rear side," the positive direction of the y-axis is sometimes called the "right side," the negative direction of the y-axis is sometimes called the "left side," the positive direction of the z-axis is sometimes called the "upper side," and the negative direction of the z-axis is sometimes called the "lower side."

[0010] Fig. 1 is a cross-sectional perspective view showing the structure of axial flow fan 1000. Fig. 2 is a cross-sectional view showing the structure of axial flow fan 1000. Axial flow fan 1000 is a ventilation device installed in a tunnel for automobiles to expel harmful substances such as soot, carbon monoxide, and nitrogen oxides emitted from automobiles out of the tunnel and send fresh air into the tunnel. Axial flow fan 1000 includes a casing 100, an electric motor 200, an axial flow fan 210, a first hub cone portion 220, and a second hub cone portion 230.

[0011] The casing 100 is a tubular structure extending from a first end 110 to a second end 120, and may be cylindrical or rectangular. In this embodiment, the casing 100 is cylindrical. A first opening 112 is disposed on the first end 110 side of the casing 100, and a second opening 122 is disposed on the second end 120 side. The first opening 112 and the second opening 122 are connected to a hollow space 130 disposed inside the casing 100. The casing 100 is installed, for example, by hanging it near the ceiling of a tunnel using mounting brackets. The casing 100 may also have a sound-absorbing section formed inside using sound-absorbing material, a perforated plate, or the like. The central axis of the casing 100, i.e., the central axis of the hollow space 130, is parallel to a rotation shaft 300 of the electric motor 200, which will be described later.

[0012] The electric motor 200 is mounted on the inner surface 132 of the hollow space 130 by a motor stay (not shown). For example, the electric motor 200 is disposed in the hollow space 130 so that the distance from the first opening 112 and the distance from the second opening 122 are equal, and the electric motor 200 is disposed near the center in the inner diameter direction of the hollow space 130. The electric motor 200 has a rotating shaft 300, which is connected to the axial fan 210. The electric motor 200 rotates the axial fan 210 around the rotating shaft 300. Furthermore, the electric motor 200 is also capable of reversing the rotation direction of the rotating shaft 300.

[0013] The axial fan 210 is connected to the rotating shaft 300 of the electric motor 200. The axial fan 210 generates an airflow within the hollow space 130 by rotating. When viewed from the rear side from the first opening 112 side, the axial fan 210 can rotate clockwise or counterclockwise, i.e., in both forward and reverse directions. The axial fan 210 includes a base 212 and multiple blades 214. The base 212 is cylindrical, and multiple blades 214 are attached at equal intervals around the periphery. The base 212 is adjacent to the electric motor 200 and connected to the rotating shaft 300. For example, six blades 214 are attached to the base 212, and the cross section of the blades 214 is an axisymmetric airfoil shape. Note that the number of blades 214 may be any number, such as three or five. The cross section of the blades 214 may also be an asymmetric airfoil shape.

[0014] In this embodiment, a case will be mainly described in which the electric motor 200 rotates the axial fan 210 in a clockwise rotation direction 310 when viewed from the first opening 112 side toward the rear. In this case, in the axial flow fan 1000, air flows from the second opening 122 toward the first opening 112, that is, toward the front. This air includes a swirling flow 330 that moves forward while rotating around the rotation axis 300, that is, moves in a spiral. Of the swirling flow 330, the component that moves straight along the rotation axis 300 is the axial flow 320, and the component that rotates around the rotation axis 300 is the swirling component.

[0015] On the other hand, when viewed from the rear side from the first opening 112 side, if the motor 200 rotates the axial fan 210 counterclockwise, the air in the axial flow fan 1000 flows from the first opening 112 to the second opening 122, that is, toward the rear side. By switching the rotation direction of the axial flow fan 210, the air blowing direction can be switched in response to changes in the volume of automobile traffic passing through the tunnel, the direction of natural wind, or a fire occurring inside the tunnel, for example.

[0016] First hub cone portion 220 is disposed in front of electric motor 200 in hollow space 130. This can also be said to be disposed closer to first opening 112 than axial fan 210. First hub cone portion 220 is attached to inner surface 132 of hollow space 130 by first stay portions 224a to 224d, collectively referred to as first stay portion 224. First hub cone portion 220 has a hemispherical shape that protrudes forward. First hub cone portion 220 has an internal sound-absorbing portion formed of sound-absorbing material, a perforated plate, or the like. First hub cone portion 220 may have a substantially conical shape instead of a hemispherical shape. First hub cone portion 220 rectifies the flow of air, including swirling flow 330, from axial fan 210.

[0017] First stay portion 224a to first stay portion 224d are fixed to inner surface 132 of casing 100 and support first hub cone portion 220 in hollow space 130. Four first stay portions 224a to 224d are provided at equal intervals circumferentially from first hub cone portion 220 in a cross section parallel to the yz plane. The number of first stay portions 224 may be three, five, or more.

[0018] Here, Figure 3 will also be used to explain the structure of first stay portion 224a to first stay portion 224d in more detail. Figure 3 is an enlarged view of region R1 in Figure 2 near first stay portion 224b. First stay portion 224b is a plate-shaped member and includes a stay portion first end 242 located on the axial fan 210 side, a stay portion second end 244 located on the first opening 112 side, and a stay portion side surface 246 connecting stay portion first end 242 and stay portion second end 244. Here, the axial fan 210 side corresponds to the rear side, and the first opening 112 side corresponds to the front side.

[0019] On the stay portion side surface 246, an imaginary line connecting the stay portion first end 242 and the stay portion second end 244 is inclined with respect to the rotation axis 300. As described above, the axial fan 210 rotates in a clockwise rotation direction 310. In accordance with the clockwise rotation direction 310 of the axial fan 210, the stay portion first end 242 is disposed closer to the clockwise rotation direction 310 than the stay portion second end 244. Specifically, on the first stay portion 224b, the stay portion first end 242 is disposed lower than the stay portion second end 244. For example, on the first stay portion 224b, an imaginary line connecting the stay portion first end 242 and the stay portion second end 244 has an inclination angle θ1 with respect to the rotation axis 300. The inclination angle θ1 is set to be equal to or greater than 3 degrees and equal to or less than 45 degrees, preferably equal to or greater than 3 degrees and equal to or less than 10 degrees. The clockwise direction of the inclination angle is defined as positive.

[0020] In addition, in the first stay portion 224a, the stay portion first end 242 (not shown) is disposed to the right of the stay portion second end 244 (not shown), and in the first stay portion 224c, the stay portion first end 242 (not shown) is disposed to the left of the stay portion second end 244 (not shown). Furthermore, in the first stay portion 224d (not shown), the stay portion first end 242 (not shown) is disposed above the stay portion second end 244 (not shown).

[0021] Here, each blade 214 of the axial fan 210 is inclined in the same direction as the stay portion side surface 246 relative to the rotation axis 300. The inclination angle of the blade 214 relative to the rotation axis 300 may be different from the inclination angle of the stay portion side surface 246 relative to the rotation axis 300. As a result, swirling flow 330 generated by the rotation of the axial fan 210 is shown as swirling flow 330a to swirling flow 330c. An imaginary line of the stay portion side surface 246 is inclined relative to the rotation axis 300 so that at least a portion of the air containing swirling flow 330 from the axial fan 210, such as swirling flow 330a, collides with the stay portion side surface 246. The swirling flow 330a that collides with the stay portion side surface 246 travels along the rotation axis 300. While pressure loss is not reduced because the swirling flow collides with the first stay portion 224, arranging the first stay portion 224 at an inclination angle θ1 increases the straightness of the airflow. As a result, the swirling component of the swirling flow 330 is suppressed.

[0022] In the following, to clarify the effect of the inclination angle θ1 of the first stay portion 224, a comparison example will be described with reference to FIGS. 4 and 5. FIG. 4 is an enlarged view of the vicinity of a stay portion 250 for comparison. The stay portion 250 includes a stay portion first end 252, a stay portion second end 254, and a stay portion side surface 256. The stay portion first end 252, the stay portion second end 254, and the stay portion side surface 256 correspond to the stay portion first end 242, the stay portion second end 244, and the stay portion side surface 246 of the first stay portion 224b, respectively. An imaginary line connecting the stay portion first end 252 and the stay portion second end 254 of the stay portion 250 is aligned with the rotation axis 300. Compared to the case of FIG. 3, even when the swirling flow 330a flows through the stay portion 250, the swirling flow 330a does not travel along the rotation axis 300, and therefore the swirling component of the swirling flow 330 is less suppressed.

[0023] FIG. 5 is an enlarged view of the vicinity of a stay portion 260 for comparison. The stay portion 260 includes a stay portion first end 262, a stay portion second end 264, and a stay portion side surface 266. The stay portion first end 262, the stay portion second end 264, and the stay portion side surface 266 correspond to the stay portion first end 242, the stay portion second end 244, and the stay portion side surface 246 of the first stay portion 224b, respectively. The stay portion first end 262 is disposed on the counterclockwise rotation side of the stay portion second end 264. For example, an imaginary line connecting the stay portion first end 262 and the stay portion second end 264 of the stay portion 260 has an inclination angle θ2 with respect to the rotation axis 300. The inclination angle θ1 is a negative angle, e.g., −5 degrees. 3, even when swirling flow 330a flows through stay portion 250, swirling flow 330a does not flow along rotation axis 300, so there is less suppression of the swirling component of swirling flow 330. Return to FIGS.

[0024] The second hub cone portion 230 is disposed rearward of the axial fan 210 in the hollow space 130. This can also be said to mean that the second hub cone portion 230 is disposed closer to the second opening 122 than the axial fan 210. The second hub cone portion 230 is attached to the inner surface 132 of the hollow space 130 by second stay portions 234a to 234d, collectively referred to as second stay portions 234. The second hub cone portion 230 has a hemispherical shape that protrudes toward the rear. The second hub cone portion 230 may have a substantially conical shape instead of a hemispherical shape. When air flows toward the rear of the axial flow blower 1000, the second hub cone portion 230 straightens the air flow, including the swirling flow from the axial fan 210, i.e., the air flow moving toward the rear.

[0025] Second stay portion 234a to second stay portion 234d are fixed to inner surface 132 of casing 100, and support second hub cone portion 230 in hollow space 130. Four second stay portions 234a to second stay portion 234d are provided at equal intervals circumferentially from second hub cone portion 230 in a cross section parallel to the yz plane. The number of second stay portions 234 may be three, five, or more.

[0026] The second stay portion 234 is inclined in the same direction as the first stay portion 224 with respect to the rotation shaft 300. That is, the first stay portion 224, the second stay portion 234, and each blade 214 of the axial fan 210 are inclined in the same direction with respect to the rotation shaft 300. Furthermore, the inclination angle of the second stay portion 234 may be the same as the inclination angle of the first stay portion 224. The inclination angle of the second stay portion 234 may be different from the inclination angle of the first stay portion 224, and the number of second stay portions 234 may be different from the number of first stay portions 224. For example, the number of second stay portions 234 may be greater than the number of first stay portions 224. Furthermore, when air does not flow toward the rear side of the axial flow fan 1000, the second stay portion 234 may be disposed without inclining with respect to the rotation shaft 300.

[0027] According to this embodiment, the imaginary line connecting the stay portion first end 242 and the stay portion second end 244 of the first stay portion 224 is inclined with respect to the rotation axis 300 so that at least a portion of the air including the swirling flow 330 collides, thereby reducing the swirling component of the swirling flow 330. Furthermore, the imaginary line connecting the stay portion first end 242 and the stay portion second end 244 of the first stay portion 224 is inclined with respect to the rotation axis 300 so that at least a portion of the air including the swirling flow 330 collides, thereby making it possible to direct the air in the direction of the rotation axis 300.

[0028] Furthermore, when axial fan 210 rotates clockwise as viewed from the first opening 112 side, stay portion first end 242 is disposed in a more clockwise direction than stay portion second end 244, and blades 214 are inclined in the same direction as stay portion side surface 246 relative to rotation axis 300, so air can be directed in the direction of rotation axis 300. Furthermore, second stay portion 234 is inclined in the same direction as first stay portion 224 relative to rotation axis 300, so the swirling component of the swirling flow can be suppressed even when the airflow direction is switched.

[0029] An outline of one aspect of the present disclosure is as follows. (Item 1) a cylindrical casing (100) having a first opening (112) on a first end side (110), a second opening (122) on a second end side (120) opposite to the first end side (110), and a hollow space (130) connecting the first opening (112) and the second opening (122); an electric motor (200) disposed in the hollow space (130); an axial flow fan (210) attached to a rotating shaft (300) of the electric motor (200) and capable of rotating; a hub cone portion (220) that is disposed closer to the first opening (112) than the axial flow fan (210) in the hollow space (130) and that rectifies the flow of air including a swirling flow (330) from the axial flow fan (210); a stay portion (224) fixed to the casing (100) and supporting the hub cone portion (220) in the hollow space (130); The stay portion (224) is a plate-like member and includes a stay portion first end (242) located on the axial fan (210) side, a stay portion second end (244) located on the first opening (112) side, and a stay portion side surface (246) connecting the stay portion first end (242) and the stay portion second end (244), an imaginary line connecting the stay portion first end (242) and the stay portion second end (244) of the stay portion side surface (246) is inclined with respect to the rotation axis (300) so that at least a part of the air including the swirling flow (330) from the axial flow fan (210) collides with the stay portion side surface (246); Axial blower (1000).

[0030] (Item 2) the axial flow fan (210) has blades (214) and rotates clockwise when viewed from the first opening (112), The stay portion first end (242) is disposed in the clockwise direction relative to the stay portion second end (244), The blades (214) are inclined in the same direction as the stay portion side surface (246) with respect to the rotation axis (300). 10. The axial flow fan (1000) of claim 1.

[0031] (Item 3) the hub-cone portion (220) is a first hub-cone portion (220), the stay portion is a first stay portion (224), The axial flow fan (210) rotates counterclockwise when viewed from the first opening (112), The axial flow fan (1000) a second hub cone portion (230) that is disposed closer to the second opening (122) than the axial flow fan (210) in the hollow space (130) and that straightens the flow of air including a swirling flow (330) from the axial flow fan (210); a second stay portion (234) fixed to the casing (100) and supporting the second hub cone portion (230) in the hollow space (130), The second stay portion (234) is inclined in the same direction as the first stay portion (224) with respect to the rotation axis (300). 3. An axial flow fan (1000) according to claim 2.

[0032] The present disclosure has been described above based on examples. These examples are merely illustrative, and it will be understood by those skilled in the art that various modifications are possible in the combination of each component or each treatment process, and that such modifications are also within the scope of the present disclosure.

[0033] In this embodiment, the first stay portion 224 and the second stay portion 234 are plate-shaped members. However, this is not limiting. For example, the first stay portion 224 may have a trapezoidal surface in which the length of the edge portion on the first hub cone portion 220 side (hereinafter referred to as the "first length") is different from the length of the edge portion on the inner surface 132 side (hereinafter referred to as the "second length"). In this case, the first length may be longer or shorter than the second length. Furthermore, in the first stay portion 224, the thickness of the edge portion on the first hub cone portion 220 side may be different from the thickness of the edge portion on the inner surface 132 side. Furthermore, the cross section of the first stay portion 224 on the inner surface 132 side may be streamlined. The same applies to the second stay portion 234. This modification improves the degree of freedom in the structure. [Explanation of symbols]

[0034] 100 casing, 110 first end, 112 first opening, 120 second end, 122 second opening, 130 hollow space, 132 inner surface, 200 electric motor, 210 axial flow fan, 212 base, 214 blade, 220 first hub cone portion, 224 first stay portion, 230 second hub cone portion, 234 second stay portion, 242 stay portion first end, 244 stay portion second end, 246 stay portion side surface, 250 stay portion, 252 stay portion first end, 254 stay portion second end, 256 stay portion side surface, 260 stay portion, 262 stay portion first end, 264 stay portion second end, 266 stay portion side surface, 300 rotating shaft, 310 rotation direction, 320 axial flow, 330 swirl flow, 1000 axial flow blower.

Claims

1. a cylindrical casing having a first opening on a first end side, a second opening on a second end side opposite to the first end side, and a hollow space connecting the first opening and the second opening; an electric motor disposed in the hollow space; a rotatable axial flow fan attached to a rotary shaft of the electric motor; a hub cone portion that is disposed closer to the first opening than the axial flow fan in the hollow space and that rectifies the flow of air including the swirling flow from the axial flow fan; a stay portion fixed to the casing and supporting the hub cone portion in the hollow space, the stay portion is a plate-like member and includes a stay portion first end located on the axial fan side, a stay portion second end located on the first opening side, and a stay portion side surface connecting the stay portion first end and the stay portion second end, an imaginary line connecting the first end of the stay portion and the second end of the stay portion is inclined with respect to the rotation axis so that at least a part of the air including the swirling flow from the axial flow fan collides with the stay portion side surface; Axial blower.

2. the axial flow fan has blades and rotates clockwise when viewed from the first opening side; the first end of the stay portion is disposed in the clockwise direction relative to the second end of the stay portion, The blades are inclined in the same direction as the side surfaces of the stay portions with respect to the rotation axis.

2. The axial flow fan according to claim 1.

3. the hub cone portion is a first hub cone portion, the stay portion is a first stay portion, the axial flow fan rotates counterclockwise when viewed from the first opening side, The axial flow fan is a second hub cone portion that is disposed closer to the second opening than the axial flow fan in the hollow space and that rectifies the flow of air including the swirling flow from the axial flow fan; a second stay portion fixed to the casing and supporting the second hub cone portion in the hollow space, The second stay portion is inclined in the same direction as the first stay portion with respect to the rotation axis.

3. The axial flow fan according to claim 2.

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