Fan unit

Abstract

To realize a fan unit that contributes to increasing heating efficiency to a workpiece.SOLUTION: A fan unit (1) according to an aspect of the disclosure comprises a fan body (2) disposed in a flow channel (11) of a heat processing furnace (10) and a flow adjustment section (3) disposed in a part on an upstream side of hot air in a bending part (11a) of the flow channel (11) with respect to the fan body (2). The flow adjustment section (3) includes: a first flow adjustment member (32) that constrains the hot air that flows into an inner diameter side of the bending part (11a), when flowing downstream, from flowing into an outer diameter side of the bending part (11a) and guides the hot air to the inner diameter side of the bending part (11a); and a second flow adjustment member (33) that introduces, when the hot air that flows into the inner diameter side of the bending part (11a) flows downstream, the hot air into the inner diameter side of the bending part (11a).SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a fan unit, for example, a fan unit arranged in a flow path of a hot air circulation type heat treatment furnace for heating a workpiece. [Background technology]

[0002] The heat treatment furnace for heating the workpiece is configured to forcibly circulate hot air by a fan. For example, the heat treatment furnace of Patent Document 1 is configured to circulate hot air by a fan in the order of a heating zone, a supply zone, and a heat treatment zone. At this time, the supply zone of Patent Document 1 is divided into a plurality of flow paths from the inner diameter side to the outer diameter side by a straightening plate. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-17425 A Summary of the Invention [Problem to be solved by the invention]

[0004] The present applicant has found the following problem. In the heat treatment furnace of Patent Document 1, when hot air passes through each flow path, the flow rate of the hot air is reduced on the inner diameter side of the curved portion downstream of the flow of the hot air. As a result, in each flow path, the circulating flow rate of the hot air in the heat treatment furnace is reduced on the inner diameter side of the curved portion, resulting in a problem of low workpiece heating efficiency.

[0005] The present disclosure has been made in consideration of such problems, and realizes a fan unit that contributes to improving the heating efficiency of a workpiece. [Means for solving the problem]

[0006] A fan unit according to one aspect of the present disclosure is a fan unit arranged in a flow path of a hot air circulation type heat treatment furnace for heating a workpiece, A fan body disposed in the flow path; a straightening section that is disposed in a portion of the curved portion of the flow path upstream of the flow of hot air relative to the fan body, and that guides the hot air that flows in from the outside of the fan body at the curved portion when viewed from the direction in which the central axis of the rotary fan of the fan body extends, to the rotary fan; Equipped with The rectifying unit includes: a first straightening member that suppresses hot air flowing into the inner diameter side of the curved portion from flowing into the outer diameter side of the curved portion when the hot air flows downstream of the flow of the hot air, and guides the hot air to the inner diameter side of the curved portion; a second straightening member that draws the hot air flowing into the inner diameter side of the curved portion when the hot air flows to the downstream side; Equipped with.

[0007] In the above-mentioned fan unit, it is preferable that the first straightening member is formed in a circular ring shape when viewed from the direction in which the central axis of the rotating fan extends, and is formed so as to incline radially outward of the first straightening member as it moves toward the opposite side relative to the fan body.

[0008] In the above-mentioned fan unit, the rectifying section includes a housing that surrounds a peripheral portion of the rotary fan, It is preferable that the second flow straightening member is provided at the upstream end of the housing and is disposed on the inner diameter side of the curved portion with respect to the first flow straightening member.

[0009] In the above-mentioned fan unit, it is preferable that the second straightening member is formed in a circular ring shape when viewed from the direction in which the central axis of the rotating fan extends, and is formed so as to incline toward the radially outward side of the second straightening member as it moves toward the opposite side relative to the fan body.

[0010] In the above-described fan unit, it is preferable that the second flow straightening member protrudes from the upstream end of the housing toward the opposite side relative to the fan body. Effect of the Invention

[0011] According to the present disclosure, a fan unit that contributes to improving the heating efficiency of a workpiece can be realized. [Brief description of the drawings]

[0012] [Figure 1] 4 is a partial cross-sectional view showing a state in which a fan unit according to an embodiment is incorporated into a flow passage of a heat treatment furnace. FIG. [Diagram 2] 4 is a perspective view showing a straightening portion in the fan unit according to the embodiment; FIG. [Diagram 3] FIG. 1A is a diagram showing the flow of hot air at a curved portion of the flow path of a heat treatment furnace when a fan unit of an embodiment is incorporated into the flow path of the heat treatment furnace, and FIG. 1B is a diagram showing the flow of hot air at a curved portion of the flow path of a heat treatment furnace when the straightening section of the fan unit is omitted. [Figure 4] FIG. 13 is a diagram showing the relationship between the diameter position of the rotating fan and the flow rate of hot air in the flow path of a heat treatment furnace incorporating a fan unit of an embodiment, and the relationship between the diameter position of the rotating fan and the flow rate of hot air in the flow path of a heat treatment furnace in which the straightening section of the fan unit is omitted. [Diagram 5] 1 is a diagram showing the relationship between the circulating flow rate of hot air in a flow path of a heat treatment furnace incorporating a fan unit of an embodiment and the circulating flow rate of hot air in a flow path of a heat treatment furnace in which the straightening section of the fan unit is omitted. FIG. [Figure 6] 13 is a partial cross-sectional view showing a state in which a fan unit according to another embodiment is incorporated into a flow passage of a heat treatment furnace. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, specific embodiments to which the present disclosure is applied will be described in detail with reference to the drawings. However, the present disclosure is not limited to the following embodiments. In addition, the following description and drawings are appropriately simplified for clarity of explanation.

[0014] First, the configuration of the fan unit of this embodiment will be described. Fig. 1 is a partial cross-sectional view showing a state in which the fan unit of this embodiment is incorporated into a flow path of a heat treatment furnace. Fig. 2 is a perspective view showing a straightening section in the fan unit of this embodiment. Here, in the following description, in order to clarify the description, a three-dimensional (XYZ) coordinate system may be used. In Fig. 1, cross-sectional hatching is omitted in order to clarify the drawing.

[0015] 1 and 2, the fan unit 1 includes a fan body 2 and a straightening section 3. The fan body 2 is a so-called axial flow fan. The fan body 2 includes, for example, a rotary fan 23 having a plurality of blades 22 protruding from a boss 21 toward the radially outer side of the boss 21, and the rotary fan 23 is configured to rotate around the Z axis by the rotational driving force of a motor (not shown).

[0016] 1 and 2, the rectifying unit 3 is disposed on the +Z-axis side with respect to the fan body 2. The rectifying unit 3 includes a housing 31, a first rectifying member 32, a second rectifying member 33, a support member 34, and an attachment member 35.

[0017] 1 and 2, the housing 31 is a substantially cylindrical member extending in the Z-axis direction, and covers the peripheral edge of the rotary fan 23 of the fan body 2. In this case, the cross-sectional shape of the housing 31 is preferably substantially C-shaped so that it can be placed inside the flow path 11 of the heat treatment furnace 10, as will be described later.

[0018] 1 and 2, the first rectifying member 32 is disposed on the Z-axis + side with respect to the housing 31, and is formed in a substantially annular shape when viewed from the Z-axis direction. The first rectifying member 32 is inclined toward the radially outer side of the first rectifying member 32 as it approaches the Z-axis + side.

[0019] 1 and 2, the first flow straightening member 32 has a curved shape that is convex toward the central axis of the first flow straightening member 32. However, the first flow straightening member 32 may have an inclined surface that is inclined toward the radially outer side of the first flow straightening member 32 as it approaches the Z axis + side.

[0020] At this time, it is preferable that the outer peripheral edge of the first straightening member 32 reaches the outer peripheral edge of the housing 31 when viewed from the Z-axis direction, for example, as shown in Fig. 1. Also, it is preferable that the inner peripheral edge of the first straightening member 32 reaches near the center of the blades 22 in the radial direction of the rotary fan 23 of the fan body 2 when viewed from the Z-axis direction, for example.

[0021] As shown in Figures 1 and 2, the second straightening member 33 is positioned on the Z-axis + side of the housing 31 and on the side of the Z-axis + end of the housing 31 relative to the first straightening member 32, and is a smaller straightening member than the first straightening member 32.

[0022] 2, the second rectifying member 33 is formed in a substantially annular shape when viewed from the Z-axis direction. The second rectifying member 33 is inclined toward the radially outer side of the second rectifying member 33 as it approaches the Z-axis + side.

[0023] 1 and 2, the second rectifying member 33 has a curved shape that is convex toward the central axis of the second rectifying member 33. However, the second rectifying member 33 may have an inclined surface that is inclined toward the radially outer side of the second rectifying member 33 as it approaches the Z-axis + side.

[0024] At this time, it is preferable that the outer peripheral edge of the second flow straightening member 33 reaches the outer peripheral edge of the housing 31 when viewed from the Z-axis direction, for example, as shown in Fig. 1. Also, the inner peripheral edge of the second flow straightening member 33 is fixed, for example, to the end of the housing 31 on the Z-axis + side. Then, between the first flow straightening member 32 and the second flow straightening member 33, a part of a flow path through which the hot air flows is formed, as will be described in detail later.

[0025] 2, the support member 34 supports the first rectifying member 32 and the second rectifying member 33. The support member 34 is a plate-shaped member that is approximately parallel to a plane formed by an axis extending in the radial direction of the housing 31 and the Z axis.

[0026] As shown in FIG. 2, for example, when viewed from the circumferential direction of the housing 31, the support member 34 has a generally right-angled trapezoidal shape with its hypotenuse inclined toward the radially outer side of the housing 31 as it approaches the Z-axis + side and positioned radially inward of the housing 31.

[0027] 2, the support member 34 protrudes from the housing 31 toward the +Z-axis side, and a right-angled portion of the support member 34 on the -Z-axis side is fixed to an end portion on the +Z-axis side of the housing 31. Therefore, the support member 34 protrudes, for example, from the housing 31 toward the radially inward direction of the housing 31 when viewed from the Z-axis direction.

[0028] The support members 34 are arranged at approximately equal intervals in the circumferential direction of the housing 31, for example, as shown in Fig. 2. That is, the support members 34 are arranged approximately radially about the central axis of the housing 31 when viewed from the Z-axis direction. Then, as shown in Fig. 2, the first flow straightening member 32 and the second flow straightening member 33 are fixed to the support members 34 so as to connect the support members 34 adjacent to each other in the circumferential direction of the housing 31.

[0029] 2, the first rectifying member 32 and the second rectifying member 33 are formed in a substantially annular shape via the support member 34. The first rectifying member 32 is disposed, for example, at a portion on the negative side of the Z axis of the support member 34. The second rectifying member 33 is disposed, for example, in the vicinity of a right-angle portion on the negative side of the Z axis of the support member 34.

[0030] At this time, the central axis of the housing 31, the central axis of the first rectifying member 32, and the central axis of the second rectifying member 33 extend approximately in the Z-axis direction and are arranged approximately coaxially. Note that the support member 34 may have any shape as long as it can support the first rectifying member 32 and the second rectifying member 33 and does not provide resistance to the flow of hot air.

[0031] The mounting member 35 is used when mounting the flow straightening unit 3 to the heat treatment furnace 10. The mounting member 35 includes, for example, a support pillar 35a and a mounting plate 35b as shown in Fig. 2. The support pillar 35a is a column member extending in the Z-axis direction.

[0032] 2, the support pillar 35a is disposed outward relative to the support member 34 in the radial direction of the housing 31 and protrudes from the housing 31 to the +Z-axis side. The height of the support pillar 35a in the Z-axis direction is greater than the height of the support member 34 in the Z-axis direction. The mounting plate 35b is fixed to the end of the support pillar 35a on the +Z-axis side, and is a plate member that is approximately parallel to the XY plane.

[0033] Next, a state in which the fan unit 1 of this embodiment is incorporated into a heat treatment furnace 10 will be described. The heat treatment furnace 10 is not an essential part of this disclosure and will not be described in detail, but it is a hot air circulation type heat treatment furnace for heating a workpiece, and as shown in Fig. 1, a flow path 11 for circulating hot air is formed inside the heat treatment furnace 10.

[0034] Hot air circulates through the flow path 11 via a cylindrical member 12 disposed inside the heat treatment furnace 10. That is, the hot air flowing toward the +Z-axis side in the outer space of the cylindrical member 12 inside the heat treatment furnace 10 is heated by the burner 13 at the curved portion (i.e., the turning portion) 11a on the +Z-axis side while being guided into the inner space of the cylindrical member 12 and moves toward the -Z-axis side, and then is guided again to the outer space of the cylindrical member 12 via the curved portion on the -Z-axis side and moves toward the +Z-axis side.

[0035] As a result, the hot air circulates through the cylindrical member 12 just like a magnetic flux. At this time, for example, a shelf on which a workpiece is placed is disposed in the outer space of the cylindrical member 12 inside the heat treatment furnace 10, and the workpiece is heated by the hot air flowing through the outer space of the cylindrical member 12.

[0036] 1, the curved portion 11a has an inner diameter side portion and an outer diameter side portion that is gently curved relative to the inner diameter side portion. Note that the "inner diameter" and "outer diameter" refer to the inner diameter and outer diameter of a virtual arc that connects the outer space of the cylindrical member 12 inside the heat treatment furnace 10 and the inner space of the cylindrical member 12 inside the heat treatment furnace 10, and are not limited to cases where the curved portion 11a is arc-shaped, and the curved portion 11a may have a bent shape.

[0037] 1, the curved portion 11a has a circular ring shape when viewed from the Z-axis direction, and an outer diameter side portion 11b of the curved portion 11a at a portion downstream of the hot air of the curved portion 11a is formed in a cone shape whose diameter decreases toward the Z-axis negative side. The peripheral shape of the end portion on the Z-axis negative side of the outer diameter side portion 11b of the curved portion 11a may be substantially the same as the peripheral shape of the boss 21 of the rotary fan 23 in the fan unit 1.

[0038] At this time, it is preferable that a partition wall 14 approximately parallel to the plane formed by the radial axis of the curved portion 11a and the Z axis be suspended from the portion of the curved portion 11a on the Z axis + side in the upstream portion of the hot air of the curved portion 11a.

[0039] The partition walls 14 are preferably disposed at substantially equal intervals in the circumferential direction of the curved portion 11a. In other words, the partition walls 14 are preferably disposed substantially radially about the central axis of the curved portion 11a when viewed from the Z-axis direction.

[0040] This allows the hot air flowing toward the +Z axis side in the outer space of the cylindrical member 12 inside the heat treatment furnace 10 to be smoothly guided to the inner space of the cylindrical member 12 via the curved portion 11a.

[0041] A fan unit 1 is incorporated in the flow path 11 of the heat treatment furnace 10. In detail, as shown in Fig. 1, a boss 21 of a rotary fan 23 in the fan unit 1 is rotatably connected to a blocking portion 11c that blocks a circular space formed at an end of an outer diameter side portion 11b of a curved portion 11a of the flow path 11 of the heat treatment furnace 10 on the Z-axis negative side.

[0042] As shown in FIG. 1, when the housing 31 of the straightening unit 3 is inserted into the inner space of the cylindrical member 12 of the heat treatment furnace 10, it is supported by a protrusion that protrudes radially inward from the cylindrical member 12 and is positioned at the end of the inner space of the cylindrical member 12 on the Z-axis + side, and the mounting plate 35b of the mounting member 35 of the straightening unit 3 is fixed to the Z-axis + side portion of the curved portion 11a of the flow path 11 of the heat treatment furnace 10 in the downstream portion of the hot air of the curved portion 11a.

[0043] 1, the fan unit 1 is incorporated into the flow path 11 of the heat treatment furnace 10. At this time, the housing 31 of the flow straightener 3 is arranged so as to cover the peripheral portion of the rotary fan 23 of the fan body 2. In addition, the central axis of the rotary fan 23 of the fan unit 1, the central axis of the housing 31 of the flow straightener 3, and the central axis of the cylindrical member 12 of the heat treatment furnace 10 extend approximately in the Z-axis direction and are arranged approximately coaxially.

[0044] The support member 34 of the flow straightening unit 3 is disposed so as to be substantially continuous with the partition wall 14 of the heat treatment furnace 10 in the radial direction of the cylindrical member 12 of the heat treatment furnace 10. The mounting member 35 of the flow straightening unit 3 may have any shape as long as it can fix the flow straightening unit 3 to the flow path 11 of the heat treatment furnace 10 and does not provide resistance to the flow of hot air.

[0045] With the fan unit 1 thus incorporated into the flow path 11 of the heat treatment furnace 10, as shown in FIG. 1, the first straightening member 32 of the straightening section 3 is positioned approximately between the outer diameter portion 11b of the curved portion 11a of the flow path 11 of the heat treatment furnace 10 and the inner diameter portion of the curved portion 11a in the downstream portion of the hot air from the curved portion 11a.

[0046] 1, the second straightening member 33 of the straightening section 3 is disposed on the inner diameter side of the curved section 11a in the downstream portion of the hot air from the curved section 11a of the heat treatment furnace 10. The first straightening member 32 and the second straightening member 33 are disposed so as to incline toward the rotary fan 23 of the fan main body 2 as they approach the outer diameter side portion 11b of the curved section 11a of the flow path 11 of the heat treatment furnace 10.

[0047] Next, the flow of hot air at the curved portion 11a of the flow path 11 of the heat treatment furnace 10 when the fan unit 1 of this embodiment is incorporated into the flow path 11 of the heat treatment furnace 10 will be explained in comparison with the case where the straightening portion 3 of the fan unit 1 is omitted.

[0048] Figure 3(a) is a diagram showing the flow of hot air at a curved portion of the flow path of a heat treatment furnace when a fan unit of this embodiment is incorporated into the flow path of the heat treatment furnace, and Figure 3(b) is a diagram showing the flow of hot air at a curved portion of the flow path of a heat treatment furnace when the straightening portion of the fan unit (more specifically, the first straightening member and the second straightening member) is omitted.

[0049] FIG. 4 is a diagram showing the relationship between the diameter position of the rotating fan and the flow rate of hot air in the flow path of a heat treatment furnace incorporating the fan unit of this embodiment, and the relationship between the diameter position of the rotating fan and the flow rate of hot air in the flow path of a heat treatment furnace in which the straightening section of the fan unit is omitted.

[0050] FIG. 5 is a diagram showing the relationship between the circulating flow rate of hot air in the flow path of a heat treatment furnace incorporating the fan unit of this embodiment and the circulating flow rate of hot air in the flow path of a heat treatment furnace in which the straightening section of the fan unit is omitted.

[0051] In the curved portion 11a of the flow path 11 of the heat treatment furnace 10 in which the fan unit 1 of this embodiment is incorporated, as shown in Figure 3(a), the hot air flowing into the curved portion 11a comes into contact with the first straightening member 32 and the second straightening member 33 of the straightening section 3 of the fan unit 1 as it flows downstream.

[0052] At this time, when the hot air flowing into the inner diameter portion of the curved portion 11a of the flow path 11 of the heat treatment furnace 10 turns around and flows downstream, as shown in Figure 3(a), the first straightening member 32 prevents the hot air from flowing into the outer diameter portion 11b of the curved portion 11a, while changing the flow direction of the hot air toward the negative side of the Z axis, and guides the hot air toward the inner diameter portion of the curved portion 11a.

[0053] At the same time, as shown in Figure 3(a), when the hot air flowing into the inner diameter portion of the curved portion 11a of the flow path 11 of the heat treatment furnace 10 turns around and flows downstream while coming into contact with the second straightening member 33, the pressure around the second straightening member 33 becomes lower than the pressure in other areas.

[0054] Therefore, the hot air around the second flow straightening member 33 is drawn toward the inner diameter side portion of the curved portion 11a of the flow path 11 of the heat treatment furnace 10, which is the side of the second flow straightening member 33. As a result, when the hot air flows downstream in the curved portion 11a, it can be guided toward the inner diameter side portion of the curved portion 11a.

[0055] On the other hand, in the curved portion 11a of the flow path 11 of a heat treatment furnace in which the straightening section 3 of the fan unit 1 is omitted, as shown in Figure 3(b), the hot air flowing into the inner diameter side portion of the curved portion 11a flows into the outer diameter side portion 11b of the curved portion 11a as it flows downstream.

[0056] Therefore, as is clear from a comparison between Figures 3(a) and 3(b) and from Figure 4, the curved portion 11a of the flow path 11 of the heat treatment furnace 10 incorporating the fan unit 1 of this embodiment is able to direct hot air into almost the entire radial area of ​​the rotating fan 23 of the fan main body 2, whereas the curved portion 11a of the flow path 11 of the heat treatment furnace in which the straightening section 3 of the fan unit 1 is omitted makes it difficult to direct hot air radially outside the rotating fan of the fan main body.

[0057] As a result, a heat treatment furnace 10 incorporating the fan unit 1 of this embodiment can circulate hot air more efficiently than a heat treatment furnace in which the straightening section 3 of the fan unit 1 is omitted, and as shown in Figure 5, a heat treatment furnace 10 incorporating the fan unit 1 of this embodiment can significantly increase the circulating flow rate of hot air compared to a heat treatment furnace in which the straightening section 3 of the fan unit 1 is omitted.

[0058] As described above, the fan unit 1 of the present embodiment is provided with the rectifier 3, and therefore can significantly increase the circulating flow rate of hot air in the flow path 11 of the heat treatment furnace 10, compared to a case not provided with the rectifier 3. Therefore, the fan unit 1 of the present embodiment can raise the temperature of the workpiece in a short time, and has high workpiece heating efficiency, compared to a case not provided with the rectifier 3.

[0059] Moreover, when it is desired to ensure a predetermined circulation flow rate, the fan unit 1 of the present embodiment allows the rotary fan 23 of the fan body 2 to be made smaller in size, and also allows the motor that drives the rotary fan 23 to be made smaller, compared to a case in which the fan unit 1 does not include the rectifying section 3. This allows the heat treatment furnace 10 to be made smaller in size.

[0060] Moreover, the fan unit 1 of the present embodiment can be easily configured by adding the airflow rectifying section 3 to a general fan main body 2.

[0061] In addition, the second straightening member 33 of the fan unit 1 in this embodiment has a shape that is inclined radially outward of the second straightening member 33 as it approaches the Z-axis + side, but it may also have a convex shape that protrudes from the housing 31 toward the Z-axis + side, as shown in Figure 6.

[0062] In short, the second straightening member 33 needs to have a shape that can come into contact with the hot air flowing into the curved portion 11a of the flow path 11 of the heat treatment furnace 10, and lower the pressure around the second straightening member 33 compared to the pressure in other areas, thereby drawing the hot air flowing downstream into the inner diameter portion of the curved portion 11a.

[0063] The present disclosure is not limited to the above-described embodiment, and can be modified as appropriate without departing from the spirit and scope of the present disclosure. [Explanation of symbols]

[0064] 1 Fan Unit 2 Fan body 3 Rectifier 10 Heat treatment furnace 11 Flow Path 11a Curved section 11b A portion on the outer diameter side of the curved portion in the downstream portion of the hot air of the curved portion 11c Occlusion 12 Cylindrical member 13 Burner 14 Bulkhead 21 Boss 22 Wings 23 Rotating Fan 31 Housing 32 First flow straightening member 33 Second straightening member 34 Support member 35 mounting member, 35a support, 35b mounting plate

Claims

1. A fan unit arranged in a flow path of a hot air circulation type heat treatment furnace for heating a workpiece, A fan body disposed in the flow path; a straightening section that is disposed in a portion of the curved portion of the flow path upstream of the flow of hot air relative to the fan body, and that guides the hot air that flows in from the outside of the fan body at the curved portion when viewed from the direction in which the central axis of the rotary fan of the fan body extends, to the rotary fan; Equipped with The rectifying unit includes: a first straightening member that suppresses hot air flowing into the inner diameter side of the curved portion from flowing into the outer diameter side of the curved portion when the hot air flows downstream of the flow of the hot air, and guides the hot air to the inner diameter side of the curved portion; a second straightening member that draws the hot air flowing into the inner diameter side of the curved portion when the hot air flows to the downstream side; A fan unit comprising:

2. 2. The fan unit according to claim 1, wherein the first straightening member is formed in a circular ring shape when viewed from a direction in which a central axis of the rotating fan extends, and is formed so as to incline toward the radially outward side of the first straightening member as it moves toward the opposite side relative to the fan body.

3. The airflow rectifier includes a housing that surrounds a peripheral portion of the rotary fan, The fan unit according to claim 1 , wherein the second flow straightening member is provided at the upstream end of the housing and is disposed on an inner diameter side of the curved portion with respect to the first flow straightening member.

4. 4. The fan unit according to claim 3, wherein the second straightening member is formed in a circular ring shape when viewed from a direction in which a central axis of the rotating fan extends, and is formed so as to incline toward the radially outer side of the second straightening member as it moves toward the opposite side relative to the fan body.

5. The fan unit according to claim 3 , wherein the second flow straightening member protrudes from the upstream end of the housing toward a side opposite to the fan body.

Images