Contra-rotating fans

Abstract

Contra-rotating fans 1 comprise: a plurality of rotating bodies 200 which each have an impeller 202; a plurality of casings 100 which are arranged along the rotation axis direction of the rotating bodies and which respectively accommodate one of the plurality of rotating bodies in a manner allowing rotation; and a linking member 300 which links the plurality of casings. The plurality of casings each include: a cylindrical outer wall section 110 that has an inner peripheral surface 110a; a bottom section 120 that is provided radially inward of the inner peripheral surface; a connecting section 130 that connects the bottom section and the outer wall section; and a linking section 142 that is provided to a part of the outer wall section that is radially outward of a part where the outer wall section and the connecting section are connected. The respective linking sections of the plurality of casings face each other in the rotation axis direction. A plurality of linking sections are linked by the linking member.

Description

Double-reverse fan

[0001] The present invention relates to a double-reverse fan.

[0002] Conventionally, as shown in Patent Document 1, a double-reverse fan in which the backs of two fans are overlapped is known. According to such a double-reverse fan, the blowing force can be increased or the blowing can be diffused.

[0003] Japanese Patent Application Laid-Open No. 2020-109258

[0004] In a double-reverse fan in which two fans are connected, improvement in the durability of the connecting portion for connecting the fans is desired.

[0005] An object of the present invention is to provide a double-reverse fan capable of improving durability.

[0006] In order to solve the above problems, the double-reverse fan of the present invention includes: a plurality of rotating bodies having impellers; a plurality of casings arranged in the rotational axis direction of the rotating bodies and each rotatably accommodating one of the plurality of rotating bodies; and a connecting member connecting the plurality of casings. Each of the plurality of casings includes: a cylindrical outer wall portion having an inner peripheral surface; a bottom portion provided radially inward of the inner peripheral surface; a connecting portion connecting the bottom portion and the outer wall portion; and a connecting portion provided radially outward of a connecting portion between the outer wall portion and the connecting portion in the outer wall portion. The connecting portions of the plurality of casings face each other in the rotational axis direction, and the plurality of connecting portions are connected by the connecting member.

[0007] According to the present invention, durability can be improved.

[0008] FIG. 1 is a perspective view of a double-reverse fan according to the present embodiment. FIG. 2 is a cross-sectional view taken along line II-II of FIG. 1. FIG. 3 is an exploded perspective view of the double-reverse fan. FIG. 4 is an exploded perspective view of the fan unit. FIG. 5 is a cross-sectional view of the fan unit. FIG. 6 is a perspective view of the casing. FIG. 7 is a front view of the casing. FIG. 8 is a perspective view showing the casings with their backs together. FIG. 9 is a side view showing the casings with their backs together.

[0009] An embodiment of the present invention will be described in detail below with reference to the attached drawings. The numerical values ​​and other figures shown in this embodiment are merely illustrative for ease of understanding and do not limit the present invention unless otherwise specified. In this specification and drawings, elements having substantially the same function and configuration are denoted by the same reference numerals to avoid redundant explanations, and elements not directly related to the present invention are omitted from the illustration.

[0010] Figure 1 is a perspective view of the counter-rotating fan 1 according to this embodiment. Figure 2 is a cross-sectional view taken along line II-II in Figure 1. Figure 3 is an exploded perspective view of the counter-rotating fan 1. As shown in Figures 1 to 3, the counter-rotating fan 1 comprises a first fan unit FUa and a second fan unit FUb. The counter-rotating fan 1 is formed by connecting the first fan unit FUa and the second fan unit FUb. Although the first fan unit FUa and the second fan unit FUb differ in some aspects of their shape, their components and basic structure are the same. Therefore, in the following, when the first fan unit FUa and the second fan unit FUb are not distinguished, both will be referred to as fan unit FU. Also, components common to the first fan unit FUa and the second fan unit FUb will be given the same reference numerals.

[0011] In this example, the dual counter-rotating fan 1 is composed of two fan units FU, but it may also be composed of three or more fan units FU connected together. In other words, the dual counter-rotating fan 1 only needs to have two or more fan units FU, and the number is not particularly limited.

[0012] The fan unit FU comprises a casing 100 and a rotating body 200 rotatably housed within the casing 100. That is, the counter-rotating fan 1 comprises a plurality (in this case, two) of casings 100 and a plurality (in this case, two) of rotating bodies 200. In the counter-rotating fan 1, the plurality of casings 100 are arranged in the direction of the rotation axis of the rotating body 200. At this time, the casing 100 of the first fan unit FUa and the casing 100 of the second fan unit FUb are connected back to back, i.e., in reverse. Hereafter, the direction of rotation of the rotating body 200 or casing 100 will be simply referred to as the axial direction. Also, the direction of rotation of the rotating body 200 or casing 100 will be simply referred to as the rotational direction or circumferential direction. Also, the radial direction of the rotating body 200 or casing 100 will be simply referred to as the radial direction.

[0013] Figure 4 is an exploded perspective view of the fan unit FU. Note that in Figure 4, parts attached to the casing 100 are omitted. The casing 100 includes an outer wall portion 110, a bottom portion 120, and a connecting portion 130.

[0014] The outer wall portion 110 is cylindrical in shape and comprises an inner circumferential surface 110a and an outer circumferential surface 110b. In other words, in this case, the cross-sectional shapes perpendicular to the axial direction of both the inner circumferential surface 110a and the outer circumferential surface 110b are circular. However, the outer wall portion 110 is not limited to a cylindrical shape and may be configured as a polygonal tube. In this case, the cross-sectional shapes perpendicular to the axial direction of the inner circumferential surface 110a and the outer circumferential surface 110b may be different. For example, the cross-sectional shape of the inner circumferential surface 110a may be circular, and the cross-sectional shape of the outer circumferential surface 110b may be polygonal.

[0015] The bottom portion 120 is located radially inward of the inner circumferential surface 110a. The bottom portion 120 includes a circular bottom surface 120a and an annular circumferential surface 120b that protrudes axially from the outer edge of the bottom surface 120a. A support projection 122 is provided in the center of the bottom surface 120a. A bearing hole 122a is formed in the support projection 122, penetrating it axially. The centers of the bottom portion 120, the support projection 122, and the outer wall portion 110 coincide with each other, and this center position can be said to be the center position of the casing 100.

[0016] Here, the +X and -X directions shown in Figure 4 are axial directions, the +X direction side is referred to as the front side of the casing 100 and fan unit FU, and the -X direction side is referred to as the rear side of the casing 100 and fan unit FU. Hereafter, the front side and rear side of the casing 100 and fan unit FU will simply be referred to as the front side and the rear side. The bottom portion 120 is provided on the rear side of the axial center position of the outer wall portion 110. More specifically, the rear side of the bottom surface 120a of the bottom portion 120 is flush with the rear end surface of the outer wall portion 110. However, the rear side of the bottom surface 120a of the bottom portion 120 may be provided offset in the axial direction from the rear end surface of the outer wall portion 110. The outer wall portion 110 and the bottom portion 120 define and form the housing space 100a in which the rotating body 200 is housed.

[0017] The annular circumferential surface 120b and the support projections 122 protrude from the bottom surface 120a toward the front. In this case, the protruding height of the support projections 122 is greater than the protruding height of the annular circumferential surface 120b and less than the axial length of the outer wall portion 110. Therefore, the entire bottom portion 120 is contained within the axial range of the outer wall portion 110. On the front side of the bottom surface 120a, multiple ribs 124 are formed, extending from the outer circumferential surface of the support projections 122 to the inner circumferential surface of the annular circumferential surface 120b.

[0018] The diameters of the bottom surface 120a and the annular circumferential surface 120b are smaller than the inner diameter of the outer wall portion 110, i.e., the diameter of the inner circumferential surface 110a. Therefore, the bottom portion 120 is separated from the outer wall portion 110. The bottom portion 120 is connected to the outer wall portion 110 by connecting portions 130. Multiple connecting portions 130 are provided to connect the bottom portion 120 and the outer wall portion 110 (in this example, there are six). However, the number of connecting portions 130 is not particularly limited, and it is sufficient for the casing 100 to be provided with one or more connecting portions 130. The multiple connecting portions 130 are provided separated from each other in the rotational direction. The gap formed between two adjacent connecting portions 130 in the rotational direction becomes an air intake or discharge port.

[0019] Here, the portion of the connecting portion 130 that is connected to the bottom portion 120 is referred to as the inner end portion 130a, and the portion that is connected to the outer wall portion 110 is referred to as the outer end portion 130b. The inner end portion 130a and the outer end portion 130b are positioned offset from each other in the rotational direction, and the connecting portion 130 has a gently curved shape. However, the connecting portion 130 may be formed in a straight line or may extend along the radial direction. Also, the axial thickness of the connecting portion 130 is smaller than the axial projection height of the annular circumferential surface 120b. However, the axial thickness of the connecting portion 130 may be greater than or equal to the axial projection height of the annular circumferential surface 120b.

[0020] Figure 5 is a cross-sectional view of the fan unit FU. As shown in Figures 4 and 5, the rotating body 200 includes an impeller 202. The impeller 202 includes a cylindrical portion 202a with a low cylindrical shape and a plurality of blades 202b provided on the outer circumferential surface of the cylindrical portion 202a. When the rotating body 200 is assembled to the casing 100, as shown in Figure 5, the front surface of the cylindrical portion 202a is substantially flush with the front end of the outer wall portion 110. The rear end surface of the cylindrical portion 202a faces the annular circumferential surface 120b in the axial direction while maintaining a gap. The support projection 122 protrudes into the internal space of the cylindrical portion 202a, and the outer circumferential surface of the support projection 122 and the inner circumferential surface of the cylindrical portion 202a face each other in the radial direction.

[0021] Furthermore, the multiple blades 202b are arranged to be spaced apart from each other in the direction of rotation. When the impeller 202 rotates, an airflow is formed by the blades 202b. The direction of the airflow is determined by the shape of the blades 202b and the direction of rotation of the impeller 202. Specifically, the shape of the blades 202b and the direction of rotation of the impeller 202 create an airflow that flows from the front to the back, or from the back to the front.

[0022] A yoke 204 is provided inside the cylindrical portion 202a. The yoke 204 includes a flat portion 204a facing the bottom of the cylindrical portion 202a and an annular portion 204b extending in an annular shape along the inner circumferential surface of the cylindrical portion 202a. The flat portion 204a of the yoke 204 is fixed to the cylindrical portion 202a by fastening means such as screws. A permanent magnet 206 is fixed to the annular portion 204b of the yoke 204. The permanent magnet 206 extends in an annular shape along the inner circumferential surface of the annular portion 204b of the yoke 204. The rotating body 200 having the permanent magnet 206 and the impeller 202 functions as a rotor.

[0023] Furthermore, a holder 208 is fixed to the flat portion 204a of the yoke 204. A shaft 210 is fixed to the center of the holder 208. That is, one end of the shaft 210 is fixed to the bottom of the impeller 202 via the holder 208. The other end of the shaft 210 protrudes axially beyond the cylindrical portion 202a of the impeller 202. The shaft 210 is inserted into a bearing hole 122a formed in the support projection 122 of the casing 100. A pair of bearings 212 are provided in the bearing hole 122a, spaced apart in the axial direction, and the shaft 210 is rotatably supported by this pair of bearings 212. The bearings 212 may be sliding bearings, ball bearings, roller bearings, or any other type of rolling bearing. In this way, the rotating body 200 is rotatably housed in the housing space 100a of the casing 100.

[0024] Furthermore, the casing 100 supports the stator 220 inside the rotating body 200. Specifically, the stator 220 is supported by support projections 122 provided on the bottom 120 of the casing 100. The stator 220 includes a stator core 222 and a plurality of coils 224. The stator core 222 is constructed by laminating a plurality of magnetic materials, such as electrical steel sheets. The stator core 222 includes a cylindrical portion 222a through which the support projections 122 are inserted, and a plurality of teeth 222b extending radially outward from the cylindrical portion 222a. Generally, the cylindrical portion 222a is also called the core, and the teeth 222b are also called the magnetic pole portion.

[0025] A portion of the stator core 222 is covered by an insulator (not shown) made of an insulating material, and multiple coils 224 are wound around the insulator. In other words, the multiple coils 224 are wound around the insulator that covers each of the multiple teeth 222b of the stator core 222. As a result, the coils 224 are wound around the stator core 222 while being insulated from the stator core 222. The outer diameter of the stator 220 is slightly smaller than the inner diameter of the permanent magnet 206, and the inner surface of the permanent magnet 206 and the outer surface of the stator 220 face each other radially in a non-contact state.

[0026] A substrate 230 is provided on the rear side of the stator 220. A through hole is formed in the center of the substrate 230, and a support projection 122 is inserted through this through hole in the substrate 230. In other words, the substrate 230 is held by the support projection 122 while being inserted through it. Copper wires that form the coil 224 are connected to the substrate 230.

[0027] As described above, the fan unit FU comprises an outer rotor type motor including a rotating body 200 as a rotor, which includes an impeller 202 and a permanent magnet 206, and a stator 220 provided inside the rotating body 200. With the fan unit FU, when the coil 224 is energized by the circuit board 230, the rotating body 200 rotates with the shaft 210 as the axis of rotation.

[0028] The dual counter-rotating fan 1 is configured by connecting two of the above-mentioned fan units FU back to back. Specifically, as shown in Figure 2, the first fan unit FUa and the second fan unit FUb are connected with their bottoms 120 facing each other in the axial direction. In this case, for example, the first fan unit FUa forms an airflow from the front side (left side in Figure 2) to the back side (right side in Figure 2), and the second fan unit FUb forms an airflow from the back side (left side in Figure 2) to the front side (right side in Figure 2).

[0029] In other words, both the first fan unit FUa and the second fan unit FUb form an airflow from left to right in Figure 2. In this case, the shape of the blades 202b of the second fan unit FUb allows the air to be concentrated and delivered to a predetermined area from the front side of the second fan unit FUb. In this case, it becomes possible to deliver air with a large blowing force to a narrow area. This is particularly effective, for example, when an obstruction is provided close to the front of the second fan unit FUb. Alternatively, the shape of the blades 202b of the second fan unit FUb allows the air to be diffused and delivered over a wide area from the front side of the second fan unit FUb.

[0030] Furthermore, the dual counter-rotating fan 1 allows for independent rotation control of the rotating body 200 for each fan unit FU. Therefore, the rotational speed, rotational velocity, and rotational direction of the rotating body 200 can be made different for each fan unit FU. This allows the dual counter-rotating fan 1 to achieve optimal airflow depending on the application. However, a common shaft 210 may be used for multiple rotating bodies 200. In this case, only one stator 220 and one circuit board 230 may be provided for multiple fan units FU.

[0031] In the dual counter-rotating fan 1, which is configured by connecting a first fan unit FUa and a second fan unit FUb, improving durability is a challenge. For example, the casing 100 is provided with connecting parts for connecting the fan units FU, and these connecting parts are connected by connecting members. Since a strong fastening force acts on the connecting parts from the connecting members, the connecting parts are particularly areas where improved strength is desired. Therefore, in this embodiment, the casing 100 is configured as follows in order to improve the durability of the dual counter-rotating fan 1.

[0032] Figure 6 is a perspective view of the casing 100. Figure 7 is a front view of the casing 100. As shown in Figure 6, a first flange 140 is provided on the back side of the outer wall portion 110. The first flange 140 is provided near the back end of the outer wall portion 110 and protrudes radially outward from the outer wall portion 110. That is, the first flange 140 protrudes radially outward from the outer peripheral surface 110b of the outer wall portion 110. In this case, the back surface of the first flange 140 and the back end of the outer wall portion 110 are flush. However, the back surface of the first flange 140 and the back end of the outer wall portion 110 may be offset in the axial direction.

[0033] The first flange 140 includes four curved portions 140a that curve in the rotational direction, and four straight portions 140b provided between the four curved portions 140a, and positioned with a 90-degree phase difference in the rotational direction from each other. The center of curvature of the curved portions 140a coincides with the center of curvature of the outer circumferential surface 110b of the outer wall portion 110. The straight portions 140b extend in a straight line, and both ends of each are continuous with different curved portions 140a. The extensions of two adjacent straight portions 140b in the rotational direction are perpendicular to each other. Also, two straight portions 140b provided at positions shifted by 180 degrees in the rotational direction are parallel to each other.

[0034] In this example, the first flange 140 comprises four curved sections 140a and four straight sections 140b, but the shape of the first flange 140 is not particularly limited. Furthermore, the straight sections 140b are not an essential component; for example, one curved section 140a may extend over 360 degrees.

[0035] Furthermore, each of the four curved sections 140a is provided with a connecting section 142. In other words, the outer circumferential surface 110b of the outer wall section 110 is provided with four connecting sections 142. The connecting sections 142 protrude radially outward from the outer circumferential surface 110b of the outer wall section 110. The radial projection height of the connecting sections 142 is greater than the radial projection height of the first flange 140. Therefore, the connecting sections 142 protrude radially outward from the first flange 140.

[0036] Furthermore, the connecting portion 142 extends in the axial direction. The rear end face of the connecting portion 142 is flush with the rear surfaces of the outer wall portion 110 and the first flange 140. In contrast, the front end face of the connecting portion 142 protrudes axially more than the front surface of the first flange 140. That is, the axial thickness of the connecting portion 142 is greater than the axial thickness of the first flange 140, and less than the axial length of the outer wall portion 110.

[0037] The connecting portion 142 has a connecting hole 142a that penetrates it in the axial direction. The connecting hole 142a is located approximately in the radial center of the connecting portion 142. Here, the connecting hole 142a is located on the extension of the outer edge of the curved portion 140a. In other words, it can also be said that the connecting hole 142a penetrates the first flange 140 in the axial direction.

[0038] Furthermore, each of the four curved sections 140a is provided with a first fixing section 144. In other words, four first fixing sections 144 are provided on the outer peripheral surface 110b of the outer wall section 110. The first fixing sections 144 protrude radially outward from the outer peripheral surface 110b of the outer wall section 110. The radial projection height of the first fixing sections 144 is greater than the radial projection height of the first flange 140. Therefore, the first fixing sections 144 protrude radially outward from the first flange 140.

[0039] Furthermore, the first fixing portion 144 extends in the axial direction. The rear end face of the first fixing portion 144 is flush with the rear surfaces of the outer wall portion 110 and the first flange 140. In contrast, the front end face of the first fixing portion 144 protrudes axially from the front surface of the first flange 140. That is, the axial thickness of the first fixing portion 144 is greater than the axial thickness of the first flange 140 and less than the axial length of the outer wall portion 110. Also, the axial thickness of the first fixing portion 144 is less than the axial thickness of the connecting portion 142. In other words, the connecting portion 142 has a greater axial thickness than the first fixing portion 144.

[0040] The first fixing portion 144 has a through hole 144a that penetrates it in the axial direction. The through hole 144a is located approximately in the radial center of the first fixing portion 144. Here, the through hole 144a is located on the extension line of the outer edge of the curved portion 140a. In other words, it can also be said that the through hole 144a penetrates the first flange 140 in the axial direction.

[0041] Furthermore, as shown in Figures 6 and 7, a second flange 150 is provided on the front side of the outer wall portion 110. The second flange 150 is provided near the front end of the outer wall portion 110 and protrudes radially outward from the outer wall portion 110. That is, the second flange 150 protrudes radially outward from the outer peripheral surface 110b of the outer wall portion 110. In this case, the front surface of the second flange 150 and the front end of the outer wall portion 110 are flush. However, the front surface of the second flange 150 and the front end of the outer wall portion 110 may be offset in the axial direction.

[0042] The second flange 150 includes four curved sections 150a that curve in the rotational direction, and four straight sections 150b provided between the four curved sections 150a, and positioned with a 90-degree phase difference in the rotational direction from each other. The center of curvature of the curved sections 150a coincides with the center of curvature of the outer circumferential surface 110b of the outer wall section 110. The straight sections 150b extend in a straight line, and both ends of each are continuous with different curved sections 150a. The extensions of two adjacent straight sections 150b in the rotational direction are perpendicular to each other. Also, two straight sections 150b provided at positions shifted by 180 degrees in the rotational direction are parallel to each other.

[0043] In this example, the first flange 150 comprises four curved sections 150a and four straight sections 150b, but the shape of the first flange 150 is not particularly limited. Furthermore, the straight sections 150b are not an essential component; for example, one curved section 150a may extend over 360 degrees.

[0044] The second flange 150 faces the first flange 140 in the axial direction. Specifically, the curved portion 150a of the second flange 150 faces the curved portion 140a of the first flange 140 in the axial direction, and the straight portion 150b of the second flange 150 faces the straight portion 140b of the first flange 140 in the axial direction. Note that the shape of the second flange 150 may be the same as or different from the shape of the first flange 140. For example, the radially protruding height of the second flange 150 may be the same as or different from the radially protruding height of the first flange 140.

[0045] Also, a notch 152 is formed in the second flange 150 at a position facing the connecting portion 142 in the rotational axis direction. The notch 152 is provided in each of the four curved portions 150a of the second flange 150. The notch 152 is a recess cut radially inward from the outer peripheral edge of the second flange 150. As is also clear from FIG. 7, in a front view of the casing 100, the entire connecting hole 142a of the connecting portion 142 is visible through the notch 152. That is, due to the notch 152, the second flange 150 does not face the connecting hole 142a in the axial direction.

[0046] Also, a second fixing portion 154 is provided in each of the four curved portions 150a. In other words, four second fixing portions 154 are provided on the outer peripheral surface 110b of the outer wall portion 110. The second fixing portion 154 protrudes radially outward from the outer peripheral surface 110b of the outer wall portion 110. The radially protruding height of the second fixing portion 154 is greater than the radially protruding height of the second flange 150. Therefore, the second fixing portion 154 protrudes radially outward more than the second flange 150.

[0047] Also, the second fixing portion 154 extends in the axial direction. The axial thickness of the second fixing portion 154 is greater than the axial thickness of the second flange 150 and smaller than the axial length of the outer wall portion 110. Note that the axial thickness of the second fixing portion 154 may be the same as or different from the axial thickness of the first fixing portion 144.

[0048] The second fixing part 154 is formed with an insertion hole 154a penetrating in the axial direction. The second fixing part 154 is provided at a position axially opposed to the first fixing part 144. And the insertion hole 154a of the second fixing part 154 is axially opposed to the insertion hole 144a of the first fixing part 144. Note that the insertion hole 154a is located substantially at the center in the radial direction of the second fixing part 154. Here, the insertion hole 154a is located on the extension line of the outer peripheral edge of the curved part 150a. That is, it can also be said that the insertion hole 154a penetrates the second flange 150 in the axial direction.

[0049] As shown in FIG. 7, a lead-out hole 126 is formed in the bottom part 120. The lead-out hole 126 is provided near the outer peripheral edge of the bottom surface 120a and penetrates the bottom surface 120a in the axial direction. Further, the lead-out hole 126 penetrates the annular circumferential surface 120b in the radial direction. The lead-out hole 126 is provided to lead out a lead wire (not shown) connecting the substrate 230 and the power supply to the outside of the bottom part 120.

[0050] The lead-out hole 126 is located near the inner end part 130a which is the connection part between one connection part 130 and the bottom part 120. Here, the lead-out hole 126 is provided adjacent to the inner end part 130a. In other words, the lead-out hole 126 is provided continuously to one connection part 130. Two locking parts 130c are provided in the connection part 130 adjacent to the lead-out hole 126, that is, the connection part 130 closest to the lead-out hole 126. A locking member for fixing the lead wire to the connection part 130 is locked to the locking part 130c.

[0051] As an example, the locking part 130c is constituted by a depression, and the locking member is constituted by a binding band. In the locking part 130c, the locking member is wound around both the lead wire drawn out from the lead-out hole 126 to the outside of the annular circumferential surface 120b and the connection part 130. Thereby, the lead wire extends from the bottom part 120 to the outer wall part 110 along the connection part 130. Further, since the locking member is locked to the locking part 130c, the possibility that the locking member is displaced to the inner end part 130a or the outer end part 130b side and the lead wire becomes loose is suppressed.

[0052] In this case, the area of ​​the bottom portion 120 near the pull-out hole 126 may have reduced strength compared to other parts. In this embodiment, since the inner end portion 130a of the connecting portion 130 is provided near the pull-out hole 126, the strength of the area near the pull-out hole 126 is ensured by the connecting portion 130.

[0053] Furthermore, as shown in Figures 3 and 6, a through-hole 110c is formed in the outer wall portion 110. The through-hole 110c is provided on the rear side of the outer wall portion 110, straddling the outer wall portion 110 and the first flange 140, and passing through the outer wall portion 110 and the first flange 140 in the radial direction. The through-hole 110c also passes through the first flange 140 in the axial direction. In other words, the through-hole 110c can be described as a notch that opens on the rear side of the outer wall portion 110. The through-hole 110c is provided to pull the lead wire out to the outside of the casing 100.

[0054] The through-hole 110c is located near the outer end 130b, which is the connection point between one connecting portion 130 and the outer wall portion 110. Here, the through-hole 110c is provided adjacent to the outer end 130b. In other words, the through-hole 110c is provided continuously with one connecting portion 130. Of the outer wall portion 110, the area near the through-hole 110c may have reduced strength compared to other areas. In this embodiment, since the outer end 130b of the connecting portion 130 is provided near the through-hole 110c, the strength of the area near the through-hole 110c is ensured by the connecting portion 130.

[0055] Furthermore, as shown in Figure 7, the connecting portion 142 is provided on the radially outer side of the connecting portion 130. That is, the connecting portion 142 is provided on the radially outer side of the outer wall portion 110 relative to the connection portion between the outer wall portion 110 and the connecting portion 130. In other words, the outer end portion 130b of the connecting portion 130 is provided on the radially inner side of the connecting portion 142. Here, four connecting portions 142 are provided, and the outer end portion 130b of the connecting portion 130 is located radially inner of all four connecting portions 142. However, some of the connecting portions 142 may be provided at a position rotated relative to the outer end portion 130b.

[0056] Figure 8 is a perspective view showing back-to-back casings 100. Figure 9 is a side view showing back-to-back casings 100. When assembling the dual counter-rotating fan 1, the backs of the two casings 100 are overlapped so that the connecting portions 142 of the first fan unit FUa and the second fan unit FUb face each other in the axial direction. In this state, as shown in Figure 9, the insertion member 302 that constitutes the connecting member 300 is inserted into the connecting hole 142a. Then, with the two connecting portions 142 that face each other in the axial direction sandwiched between the two fastening portions 304 provided on the insertion member 302, a fastening force is applied so that the two fastening portions 304 are close together, thereby connecting the first fan unit FUa and the second fan unit FUb.

[0057] Thus, a strong fastening force acts on the connecting portion 142, but in the dual counter-rotating fan 1 of this embodiment, the outer end portion 130b of the connecting portion 130 is located near the connecting portion 142. Therefore, the strength is ensured especially near the connecting portion 142, and the durability of the casing 100 is improved.

[0058] Here, as an example, the insertion member 302 constituting the connecting member 300 is made of a bolt, and the fastening portion 304 constituting the connecting member 300 is made of the bolt head and a nut. That is, a nut is fastened to a bolt that is inserted through the connecting hole 142a of the two connecting portions 142. At this time, as shown in Figure 8, a notch 152 is provided at a position opposite to the connecting portion 142. By providing the notch 152, interference between the insertion member 302 inserted through the connecting hole 142a and the second flange 150 is avoided. In addition, when performing the connecting work to connect the first fan unit FUa and the second fan unit FUb, that is, the work to apply fastening force to the fastening portion 304, the second flange 150 may get in the way. By providing the notch 152, a decrease in work efficiency during the connecting work is suppressed.

[0059] Note that the connecting member 300 is not limited to a bolt and nut. For example, the connecting member 300 may be made of a screw. In this case, a screw groove may be formed in the connecting hole 142a, and the two connecting parts 142 may be connected to each other by screwing the connecting member 300 into the connecting hole 142a. In this way, when the connecting member 300 is made of a screw, one of the two connecting holes 142a does not need to be a through hole.

[0060] Furthermore, when the first fan unit FUa and the second fan unit FUb are connected, the first fixing portion 144 of the first fan unit FUa and the first fixing portion 144 of the second fan unit FUb face each other in the axial direction. Then, in each of the first fan unit FUa and the second fan unit FUb, the fixing member 310, shown by the dashed line in Figure 9, is inserted through the insertion hole 144a of the first fixing portion 144 and the insertion hole 154a of the second fixing portion 154. The fixing member 310 is fixed to a device or the like to which the counter-rotating fan 1 is attached. In other words, the first fixing portion 144 and the second fixing portion 154 function as attachment parts for fixing the counter-rotating fan 1 to a device or the like.

[0061] As is clear from Figure 9, the connecting portion 142 has a greater axial thickness than the first fixing portion 144 and the second fixing portion 154. Although the fixing member 310 is inserted through the first fixing portion 144 and the second fixing portion 154, basically no external force acts on the first fixing portion 144 and the second fixing portion 154. In contrast, as described above, a strong fastening force acts on the connecting portion 142. In this embodiment, the strength of the connecting portion 142 is improved by making the axial thickness of the connecting portion 142 greater than that of the first fixing portion 144 and the second fixing portion 154. However, the axial thickness of the connecting portion 142 may be less than or equal to the axial thickness of the first fixing portion 144.

[0062] As shown in Figure 8, the outer wall portion 110 is provided with a first flange 140 and a second flange 150. The first flange 140 is provided with a straight section 140b, and the second flange 150 is provided with a straight section 150b. Each of the four straight sections 140b has one straight section 150b facing it in the axial direction, and the axially opposing straight sections 140b and straight sections 150b are parallel. In other words, the outermost radial sides of the outer wall portion 110 are provided.

[0063] Furthermore, the extensions of two adjacent straight sections 140b and 150b in the direction of rotation are perpendicular. Here, the connecting section 142, the first fixing section 144, and the second fixing section 154 are provided within the area enclosed by the two perpendicular extensions and the curved sections 140a and 150a. Therefore, for example, the connecting section 142, the first fixing section 144, and the second fixing section 154 do not hinder the housing of the dual counter-rotating fan 1 in a square housing. However, any of the connecting section 142, the first fixing section 144, and the second fixing section 154 may be provided on the straight sections 140b and 150b.

[0064] Note that the first flange 140 and the second flange 150 are not essential components, and either or both of them may be omitted. Also, the first fixing part 144 and the second fixing part 154 are not essential components, and either or both of them may be omitted.

[0065] Furthermore, in the counter-rotating fan 1 of this embodiment, a stator 220 is provided at the bottom 120 of the casing 100, and the rotating body 200 functions as a rotor. In other words, the counter-rotating fan 1 has a motor unit inside the casing 100. However, the motor unit is not an essential component, and for example, the motor unit may be attached externally to the counter-rotating fan 1. Alternatively, for example, the shaft 210 may extend to the outside of the casing 100, and the rotor and stator may be provided outside the casing 100.

[0066] Although one embodiment has been described above with reference to the attached drawings, it goes without saying that the present invention is not limited to the above embodiment. It is clear to those skilled in the art that various modifications or variations can be conceived within the scope of the claims, and these are also understood to fall within the technical scope.

[0067] In any case, a counter-rotating fan can have the following configuration: a plurality of rotating bodies (for example, a rotating body 200) each having an impeller (for example, an impeller 202); a plurality of casings (for example, a casing 100) arranged in the direction of the rotation axis of the rotating bodies and each rotatably housing one of the plurality of rotating bodies; and a connecting member (for example, a connecting member 300) connecting the plurality of casings, wherein each of the plurality of casings includes: a cylindrical outer wall portion (for example, an outer wall portion 110) having an inner circumferential surface (for example, an inner circumferential surface 110a); a bottom portion (for example, a bottom portion 120) provided on the radially inward side of the inner circumferential surface; a connecting portion (for example, a connecting portion 130) connecting the bottom portion and the outer wall portion; and a connecting portion (for example, a connecting portion 142) provided on the radially outward side of the outer wall portion relative to the connection portion between the outer wall portion and the connecting portion (for example, an outer end portion 130b), A dual counter-rotating fan (for example, dual counter-rotating fan 1) has multiple casings, each with a connecting section that faces the other in the direction of the rotation axis, and these multiple connecting sections are connected by a connecting member.

[0068] Furthermore, each of the multiple casings may be provided with a fixing portion (for example, a first fixing portion 144, a second fixing portion 154) through which a fixing member (for example, a fixing member 310) is inserted in the direction of the rotation axis. Also, the connecting portion may have a greater thickness in the direction of the rotation axis than the fixing portion.

[0069] Furthermore, a connecting portion and a linking portion may be provided near one end of the casing in the direction of rotation (for example, the rear side), and a flange (for example, a second flange 150) protruding radially outward from the outer wall may be provided near the other end of the casing in the direction of rotation. In addition, a notch (for example, a notch 152) may be formed in the flange at a position opposite the linking portion in the direction of rotation.

[0070] Furthermore, a flange (for example, a first flange 140), a connecting portion, and a linking portion may be provided near one end of the casing in the direction of rotation, projecting radially outward from the outer wall. The flange may also include four curved portions (for example, curved portion 140a) that curve in the direction of rotation of the rotating body, and four straight portions (for example, straight portion 140b) provided between the four curved portions and arranged with a 90-degree phase difference from each other in the direction of rotation. The linking portion may also be provided in the curved portion.

[0071] The rotating body may also include a permanent magnet (for example, a permanent magnet 206). The bottom of the casing may also be provided with a stator (for example, a stator 220) having a coil (for example, a coil 224) and a substrate (for example, a substrate 230) connected to the coil. The outer wall may also have through holes (for example, through holes 110c) through which lead wires connected to the substrate are inserted. The through holes may also be provided near the connection point between the outer wall and the connection part (for example, the outer end 130b).

[0072] 1. Counter-rotating fan 100 Casing 110 Outer wall 110a Inner surface 110c Through hole 120 Bottom 130 Connection part 130b Outer end 140 First flange 140a Curved part 140b Straight part 142 Connecting part 144 First fixing part 150 Second flange 152 Notch 200 Rotating body 202 Impeller 206 Permanent magnet 220 Stator 224 Coil 230 Circuit board 300 Connecting member 310 Fixing member

Claims

1. A double counter-rotating fan comprising: a plurality of rotating bodies having impellers; a plurality of casings arranged in the direction of the rotation axis of the rotating bodies and each rotatably housing one of the plurality of rotating bodies; and a connecting member connecting the plurality of casings, wherein each of the plurality of casings includes: a cylindrical outer wall portion having an inner circumferential surface; a bottom portion provided radially inward of the inner circumferential surface; a connecting portion connecting the bottom portion and the outer wall portion; and a connecting portion provided radially outward of the outer wall portion with respect to the connection portion between the outer wall portion and the connecting portion, wherein the connecting portions of each of the plurality of casings face each other in the direction of the rotation axis, and the plurality of connecting portions are connected by the connecting member.

2. Each of the multiple casings is provided with a fixing portion on its outer wall through which a fixing member is inserted in the direction of the rotation axis, and the connecting portion has a greater thickness in the direction of the rotation axis than the fixing portion, the dual counter-rotating fan according to claim 1.

3. The dual counter-rotating fan according to claim 1 or 2, wherein the connecting portion and the linking portion are provided near one end of the casing in the direction of rotation, a flange is provided near the other end of the casing in the direction of rotation, protruding radially outward from the outer wall, and a notch is formed in the flange at a position opposite to the linking portion in the direction of rotation.

4. A flange, a connecting portion, and a linking portion are provided near one end of the casing in the direction of rotation, projecting radially outward from the outer wall portion, the flange includes four curved portions that curve in the direction of rotation of the rotating body, and four straight portions provided between the four curved portions and arranged with a 90-degree phase difference from each other in the direction of rotation, and the linking portion is provided on the curved portion, the dual counter-rotating fan according to claim 1 or 2.

5. The rotating body includes a permanent magnet, the bottom of the casing is provided with a stator having a coil and a substrate connected to the coil, the outer wall portion has through holes through which lead wires connected to the substrate are inserted, and the through holes are provided near the connection portion between the outer wall portion and the connection portion, the dual counter-rotating fan according to claim 1 or 2.

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