Cooling device

Abstract

A cooling device is provided which is easy to assemble and provides improved cooling efficiency by preventing a back flow without fail. To this end, the cooling device has: (a) an axial fan having a plurality of vanes; (b) a power source for driving the axial fan; (c) a tubular fan ring disposed in outer edge portions of the vanes; (d) a projecting portion that extends over substantially entire circumference of the fan ring and projects in an outer peripheral direction; (e) a shroud disposed between the axial fan and an object to be cooled; and (f) an adjusting plate that is fixedly attached to the shroud so as to make a distance from an outer circumferential surface of the fan ring variable and circumferentially divided into a plurality of parts.

Description

TECHNICAL FIELD

[0001] The present invention relates to a cooling device for cooling an object by use of an axial fan.

BACKGROUND ART

[0002] There have been heretofore known engine cooling devices such as the device (hereinafter referred to as "first conventional device") disclosed in Patent Document 1, in which an object is cooled by use of an axial fan.

[0003] FIG. 10 shows a sectional side view of the first conventional device. In the first conventional device, the left side face (when viewed in FIG. 10) of an engine 101 is provided with a rotating shaft 103 rotatably attached thereto, the rotating shaft 103 having an axial fan 102 mounted on its leading end. The axial fan 102 is rotatively driven by a power transmitted from the output shaft 104 of the engine 101 through a belt 105 such that cooling air is sent to a radiator 106 located in a position opposite to the axial fan 102 to cool the radiator 106. In the following description, the longitudinal direction of the rotating shaft 103 of the axial fan 102 is referred to as "axial direction".

[0004] Attached to the outer circumferential ends of vanes 107 of the axial fan 102 is a tubular member called a fan ring 108. This fan ring 108 has projecting portions 108A, 108B at both axial ends thereof. The projecting portions 108A, 108B extend over the entire circumference of the fan ring 108, projecting toward the peripheral side, so that the fan ring 108 has a substantially U-shaped section which opens toward the peripheral side.

[0005] The radiator 106 is provided with a shroud 109 that is secured thereto by means of bolts (not shown), for guiding cooling air existing between the axial fan 102 and the radiator 106. The shroud 109 is bent, at the end on the side of the axial fan 102, toward the outer circumference of the fan ring 108 and has a circular opening 110 at the end of the bent portion.

[0006] The edge defining the circular opening 110 gets into the space between the projecting portions 108A, 108B of the fan ring 108, whereby the edge and the projecting portions 108A, 108B of the fan ring 108 form a labyrinth configuration. In this way, the cooling air is prevented from flowing back in the axial direction outside the axial fan 102 to increase the amount of cooling air.

[0007] As another prior art technique, a cooling device (hereinafter referred to as "second conventional device") is disclosed in Patent Document 2.

[0008] FIG. 11 shows a sectional side view of the second conventional device. In the second conventional device, a fan ring 108 of substantially U-shaped section similar to that of the first conventional device shown in FIG. 10 is mounted on the outer circumference of vanes 107 of an axial fan 102. In FIG. 11, the parts thereof corresponding to FIG. 10 are identified by the same reference numerals as of FIG. 10.

[0009] A shroud 109 is mounted between the axial fan 102 and the radiator 106 and a tubular body 111 is bolted to an end of the shroud 109, the end being located on the side of the axial fan 102. A reverse throttle strip 112 is projectingly attached to the inner side of the tubular body 111. The edge of this reverse throttle strip 112 forms a labyrinth configuration together with the projecting portions 108A, 108B of the fan ring 108 such that a back flow of cooling air outside the axial fan 102 is prevented.

[0010] Patent Document 1: Japanese Patent Kokai Publication No. 2002-54441

[0011] Patent Document 2: Japanese Patent Kokai Publication No. 2002-106489

DISCLOSURE OF THE INVENTION

[0012] Problems that the Invention is to Solve

[0013] The above conventional devices, however, suffer from the following problems. In the first conventional device, since the end of the shroud 109 on the side of the axial fan 102 is located In the space between the projecting portions 108A, 108B of the fan ring 108, the parts are assembled in such a way that the axial fan 102 is first positioned relative to the radiator 106 and then, the split-type shroud 109 is secured to the radiator 106 with bolts (not shown), followed by an adjustment of the distance between the end of the shroud 109 on the side of the axial fan 102 and the fan ring 108.

[0014] For uniform distribution of the amount of air sent from the axial fan 102, the distance between the end of the shroud 109 on the side of the axial fan 102 and the fan ring 108 must be substantially uniform with respect to a direction parallel to the outer circumference 113 of the fan ring 108 (hereinafter, this direction is referred to as "circumferential direction"). In order to change the position of the axial fan 102 in this situation, the engine 101 supporting the axial fan 102 needs to be moved. However, the engine 101 is bulky and heavy and it is therefore extremely difficult to align the center of the circular opening 110 of the shroud 109 and the center of the axial fan 102. This problem is significant particularly in construction machines etc. having a bulky engine.

[0015] In the case of the second conventional device, since the reverse throttle strip 112 of the tubular body 111 is located in the space between the projecting portions 108A and 108B of the fan ring 108, there is difficulty in assembling the parts, as pointed out in Patent Document 2. Taking this disadvantage into account, Patent Document 2 is designed such that the projecting length of the projecting portions 108A, 108B of the fan ring 108 is changed thereby facilitating assembling, which however results in a decrease in the effect of preventing a back flow of cooling air.

[0016] The present invention is directed to overcoming the foregoing problems and a primary object of the invention is therefore to provide a cooling device that can be easily assembled and is capable of preventing a back flow of cooling air to thereby ensure improved cooling efficiency.

[0017] Means of Solving the Problems

[0018] The above object can be achieved by a cooling device according to the invention, the device comprising:

[0019] (a) an axial fan having a plurality of vanes;

[0020] (b) a power source for driving the axial fan;

[0021] (c) a tubular fan ring disposed in outer edge portions of the vanes;

[0022] (d) a projecting portion that extends over substantially entire circumference of the fan ring and projects in an outer peripheral direction;

[0023] (e) a shroud disposed between the axial fan and an object to be cooled; and

[0024] (f) an adjusting plate that is fixedly attached to the shroud so as to make a distance from an outer circumferential surface of the fan ring variable and circumferentially divided into a plurality of parts.

[0025] In the invention, the section of the adjusting plate may be in the form of L or T.

[0026] Preferably, the number of projecting portions is at least two and an inner circumferential portion of the adjusting plate is positioned between any two of the projecting portions with respect to an axial direction of the axial fan.

[0027] The inner circumferential portion of the adjusting plate may be bifurcated and the projecting portion may be located within intermediate space of the bifurcated portion.

[0028] In the invention, the adjusting plate is preferably disposed so as to overlap the projecting portion of the fan ring when viewed in a front view of the axial fan.

[0029] The effect of the Invention

[0030] According to the invention, since the adjusting plate, which is circumferentially divided into a plurality of parts, is secured to the shroud, a fine adjustment can be made when adjusting the clearance between the shroud and the fan ring so that easy adjustment can be carried out. The use of the divided adjustment plate also facilitates assembling. Further, it enables an adjustment of the clearance between the fan ring and every divided part of the adjusting plate, which contributes to easy clearance adjustment.

[0031] By forming the adjusting plate so as to have an L-shaped or T-shaped section, the adjusting plate can be sufficiently strengthened. Further, since the part of the adjusting plate facing to the fan ring can be made to be flat, the effect of preventing a back flow can be increased. Since the adjusting plate of L-shaped section can be formed by bending a flat plate into an L-shape, it can be produced through a simple process without use of welding.

[0032] By arranging the adjusting plate so as to overlap the projecting portions of the fan ring, a back flow of cooling air becomes more unlikely to occur between the adjusting plate and the fan ring.

BRIEF DESCRIPTION OF THE DRAWINGS

[0033] FIG. 1 is a sectional side view of a cooling device according to a first embodiment of the invention.

[0034] FIG. 2 is a sectional view taken along line A-A of FIG. 1.

[0035] FIG. 3 is a detailed sectional view illustrating the vicinity of a fan ring in the cooling device of the first embodiment.

[0036] FIG. 4 is a sectional side view of a cooling device according to a second embodiment of the invention.

[0037] FIG. 5 is a detailed sectional view illustrating the vicinity of a fan ring in the cooling device according to the second embodiment.

[0038] FIG. 6 is a detailed sectional view illustrating the vicinity of a fan ring in a cooling device according to a third embodiment of the invention.

[0039] FIG. 7 is a detailed sectional view illustrating the vicinity of a fan ring in a cooling device according to a fourth embodiment of the invention.

[0040] FIG. 8 is a detailed sectional view illustrating the vicinity of a fan ring in a cooling device according to a fifth embodiment of the invention.

[0041] FIG. 9 is a detailed sectional view illustrating the vicinity of a fan ring in a cooling device according to a sixth embodiment of the invention.

[0042] FIG. 10 is a sectional side view of a first conventional device.

[0043] FIG. 11 is a sectional side view of a second conventional device.

EXPLANATION OF REFERENCE NUMERALS

[0044] 11: engine [0045] 12: axial fan [0046] 13: radiator [0047] 14A, 14B: pulley [0048] 15: fan ring [0049] 16A, 16B, 16C: projecting portion [0050] 17: shroud [0051] 18: belt [0052] 19: rotating shaft [0053] 20: tubular body [0054] 22: vanes [0055] 23: adjusting plate [0056] 24: mounting bolts [0057] 25: output shaft [0058] 26: circular opening [0059] 27: inner circumferential portion [0060] 28: large holes [0061] 29: screw holes [0062] 30: washers [0063] 31: space [0064] 32: outer circumferential portion [0065] 33: rectangular opening

BEST MODE FOR CARRYING OUT THE INVENTION

[0066] Referring now to the accompanying drawings, the cooling device of the invention will be described according to preferred embodiments.

First Embodiment

[0067] FIG. 1 shows a sectional side view of a cooling device according to a first embodiment of the invention. FIG. 2 shows a sectional view taken along line A-A of FIG. 1. FIG. 3 shows a detailed sectional view illustrating the vicinity of a fan ring in the cooling device of the first embodiment.

[0068] In the cooling device 10 of the first embodiment, an axial fan 12 having a plurality of vanes 22 is mounted to the leading end of a rotating shaft 19 and the rotating shaft 19 is rotatably attached, at the other end, to the left side face (when viewed in FIG. 1) of an engine 11. A pulley 14B is attached to the substantial center of the rotating shaft 19. A belt 18 passes around this pulley 14B and another pulley 14A that is attached to the leading end of an output shaft 25 of the engine 11. In this way, the axial fan 12 is rotatively driven by a power transmitted from the engine 11 serving as a driving source through the output shaft 25, so that cooling air flows to the right when viewed in FIG. 1. It should be noted that, in the following description, the longitudinal direction (lateral direction in FIG. 1) of the rotating shaft 19 of the axial fan 12 is referred to as "axial direction" whereas a direction parallel to the diameter of the axial fan 12 is referred to as "radial direction".

[0069] A tubular member called a fan ring 15 is attached to the outer circumferential ends of the vanes 22 of the axial fan 12 so as to entirely enclose the circumference of the vanes 22. This fan ring 15 has projecting portions 16A, 16B that are located at both axial ends thereof so as to extend over the entire circumference of the fan ring 15, projecting toward a peripheral side, whereby the fan ring 15 has a substantially U-shaped section that opens toward the peripheral side.

[0070] Herein, one example of the material suitably used for the axial fan 12 is plastics and it is preferable to form the axial fan 12 integrally with the vanes 22 and the fan ring 15, using injection molding. Alternatively, aluminum or aluminum alloys etc. may be used.

[0071] In a position opposed to the engine 11 with the axial fan 12 located therebetween, a radiator 13 serving as an object to be cooled is disposed on a mount (not shown) different from that of the engine 11. Fixedly attached to the axial fan 12 side of the radiator 13 is a shroud 17 for guiding cooling air.

[0072] As shown in FIGS. 1, 2, the shroud 17 has a rectangular opening 33 on the radiator 13 side and the rectangular opening 33 has, for instance, a square shape that fits the shape of the radiator 13. The shroud 17 is bent, at the end on the side of the axial fan 12, toward the outer circumference of the fan ring 15 such that the end of the bent portion defines a circular opening 26.

[0073] At the end of the shroud 17 on the side of the axial fan 12, an adjusting plate 23 in circular-arc form is fixed by means of mounting bolts 24 and washers 30. As described later, an inner circumferential portion (inner circumferential edge) 27 of the adjusting plate 23 is smaller in diameter than the circular opening 26. As shown in FIG. 2, the adjusting plate 23 is configured to be divided into two parts with respect to a circumferential direction such that the two parts of the adjusting plate 23 can be freely attached to and detached from the shroud 17 independently from each other.

[0074] As shown in FIGS. 2, 3, the adjusting plate 23 has large holes (long holes) 28 that are aligned at substantially equal intervals in a circumferential direction. At the end of the shroud 17 on the side of the axial fan 12, screw holes 29 (see FIG. 3) are aligned in a circumferential direction, being located in the positions corresponding to the large holes 28. The mounting bolts 24 respectively penetrating through the washers 30 are screwed into the screw holes 29 through the large holes 28, thereby fixedly attaching the adjusting plate 23 to the shroud 17.

[0075] After the adjusting plate 23 is fixedly attached in the manner described above, the position of the adjusting plate 23 with respect to the axial direction is such that the adjusting plate 23 reaches a space between the projecting portions 16A, 16B of the fan ring 15 mounted on the outer circumference of the vanes 22 of the axial fan 12 as shown in FIG. 3.

[0076] In FIG. 3, .phi.D1<.phi.D2 is satisfied as discussed earlier where the diameter of the inner circumferential portion 27 of the adjusting plate 23 is represented by .phi. D1 and the diameter of the circular opening 26 of the shroud 17 by .phi. D2. Where the outer diameter of the projecting portion 16A of the fan ring 15 on the side of the radiator 13 is represented by .phi. d1 and the outer diameter of the projecting portion 16B of the fan ring 15 on the side of the engine 11 by .phi. d2, .phi.D1<.phi.d1 and .phi.d2<.phi.D2. Although .phi.d1=.phi.d2 usually holds, .phi. d1 may be unequal to .phi. d2 (.phi.d1.noteq..phi.d2) on condition that D1<.phi.d1 and .phi.d2<.phi.D2.

[0077] The cooling device 10 of this embodiment is designed as described above. When dismounting the axial fan 12, the two-part type adjusting plate 23, which is divided into two parts with respect to the circumferential direction, is detached from the shroud 17. Thereby, a big clearance is created between the axial fan 12 and the shroud 17, so that the axial fan 12 can be easily dismounted. Mounting of the axial fan 12 is carried out in a similar way. Specifically, the axial fan 12 is mounted with a big clearance being present between the axial fan 12 and the shroud 17 and thereafter, the upper and lower parts of the adjusting plate 23 are respectively attached to the shroud 17. Mounting/dismounting of the shroud 17 is also done in a similar way. Specifically, the shroud 17 is mounted or dismounted with the adjusting plate 23 being detached from the shroud 17.

[0078] As described earlier, the cooling device of the first embodiment is configured such that the adjusting plate 23 having the circular-arc-shaped inner circumferential portion 27 is mounted in the circular opening 26 of the shroud 17, in relation to the axial fan 12 provided with the fan ring 15 that is located at the outer circumference of the vanes 22 and has two projecting portions 16A, 16B. Therefore, the first embodiment has such an advantage that the clearance between the axial fan 12 and the shroud 17 can be increased by detaching the adjusting plate 23 to facilitate mounting/dismounting of the axial fan 12.

[0079] In addition, by attaching the adjusting plate 23 after assembling the axial fan 12 and the shroud 17, the projecting portions 16A, 16B of the fan ring 15 can be positioned on the outer peripheral side of the inner circumferential portion 27 of the adjusting plate 23. Thereby, the adjusting plate 23 and the fan ring 15 of the axial fan 12 overlap each other in a front view so that the resistance to a current of air that reversely flows around the outer circumference of the vanes 22 of the axial fan 12 increases (this resistance is hereinafter referred to as "resistance to an air current in a reverse direction"). Accordingly, a back flow of cooling air can be mitigated and, as a result, the effect of increasing the amount of cooling air and therefore cooling ability can be achieved.

[0080] In addition, since the adjusting plate 23 has the large holes 28, the distance in a radial direction between the adjusting plate 23 and an outer circumferential portion 32 of the fan ring 15 can be easily adjusted to a desirable value and made to be substantially uniform in a circumferential direction. As a result, the resistance to an air current in a reverse direction has a desirable value and becomes substantially uniform in a circumferential direction, so that the amount of cooling air increases and becomes substantially uniform in a circumferential direction.

[0081] As illustrated in FIG. 3, the shroud 17 of a box type is used, so that a wide spacing between the radiator 13 and the axial fan 12 can be ensured and the distribution of cooling air that passes through the radiator 13 can be made to be uniform.

[0082] The first embodiment has been discussed with a case where the fan ring 15 has two projecting portions 16A, 16B on both axial ends respectively. This arrangement makes the fan ring 15 easy to manufacture and have sufficient strength. However, the shape of the projecting portions is not necessarily limited to this. For instance, the axial positions of the projecting portions 16A, 16B may be other positions than both ends of the fan ring 15. The number of projecting portions is not necessarily limited to two but may be one or three or more.

Second Embodiment

[0083] FIG. 4 shows a sectional side view of a cooling device according to a second embodiment of the invention. FIG. 5 shows a detailed sectional view illustrating the vicinity of a fan ring in the cooling device of the second embodiment.

[0084] In the cooling device 10A of the second embodiment, the parts that are substantially equivalent or correspond to the first embodiment are identified by the same reference numerals as of the first embodiment, and a detailed explanation thereof is skipped herein. In the following description, only the features inherent to the second embodiment will be described (in other embodiments, only their inherent features will be described too).

[0085] In the second embodiment, the adjusting plate 23 is composed of a mounting portion 23A attached to the shroud 17 and a back flow preventing portion 23B perpendicular to the mounting portion 23A. The adjusting plate 23 has an L-shaped section. The inner circumferential portion 27 of the back flow preventing portion 23B is substantially parallel to the outer circumferential portion 32 of the fan ring 15. Hereinafter, the adjusting plate 23 of the second embodiment is referred to as "L-shaped adjusting plate 23".

[0086] The L-shaped adjusting plate 23 is superior in strength to the flat adjusting plate 23 such as shown in the first embodiment (hereinafter referred to as "I-shaped adjusting plate 23"). As a result, even if the axial fan 12 or the engine 11 vibrates, the L-shaped adjusting plate 23 is unlikely to displace and therefore the noise caused by the vibration of the adjusting plate 23 decreases.

[0087] In the L-shaped adjusting plate 23, the space 31 between the inner circumferential portion 27 of the back flow preventing portion 23B and the outer circumferential portion 32 of the fan ring 15 takes the form of a choke that once makes a fluid shrink rapidly in the axial direction and then makes it expand rapidly in the axial direction after a while.

[0088] In contrast with this, the corresponding space in the I-shaped adjusting plate 23 of the first embodiment is in the form of an orifice that makes a fluid expand rapidly immediately after rapid shrinking. Compared to the orifice type, the choke type has great air current resistance so that the resistance to an air current in a reverse direction increases. Therefore, the L-shaped adjusting plate 23 provides a great amount of cooling air, compared to the I-shaped adjusting plate 23.

[0089] According to the L-shaped adjusting plate 23, the distance between the axial ends of the back flow preventing portion 23B and the projecting portions 16A, 16B of the fan ring 15 can be reduced so that the resistance to an air current in a reverse direction increases resulting in an increasing amount of cooling air.

[0090] The outer circumferential portion 32 of the fan ring 15 rotates in parallel with the inner circumferential portion 27 of the back flow preventing portion 23B, so that the air within the space 31 is drug by the movement of the fan ring 15, causing a current of air in a circumferential direction. This current of air in a circumferential direction blocks the back flow of air around the outer circumference of the vanes 22 of the axial fan 12 like an air curtain with the result that the resistance to an air current in a reverse direction further increases. In addition, the L-shaped adjusting plate 23 has the advantage that it can be manufactured at low cost by bending a flat plate to form the mounting portion 23A and the back flow preventing portion 23B.

Third Embodiment

[0091] FIG. 6 shows a detailed sectional view illustrating the vicinity of a fan ring in a cooling device according to a third embodiment of the invention.

[0092] The cooling device 10B of the third embodiment employs the L-shaped adjusting plate 23 that does not differ from that of the second embodiment except that the L-shaped adjusting plate 23 of the third embodiment faces in a direction opposite to that of the second embodiment.

Fourth Embodiment

[0093] FIG. 7 shows a detailed sectional view illustrating the vicinity of a fan ring in a cooling device according to a fourth embodiment of the invention.

[0094] The cooling device 10C of the fourth embodiment has an adjusting plate 23 in the form of that is formed by bending the leading end of the L-shaped adjusting plate constructed according to the second embodiment once more toward the outer peripheral side. Of course, the adjusting plate of the fourth embodiment may be formed by bending, at its leading end, the adjusting plate of the third embodiment into the form of .

Fifth Embodiment

[0095] FIG. 8 shows a detailed sectional view illustrating the vicinity of a fan ring in a cooling device according to a fifth embodiment of the invention.

[0096] The cooling device 10D of the fifth embodiment has an adjusting plate 23 of T-shaped section. The adjusting plate 23 of this embodiment is manufactured by fixedly attaching a plate 23C serving as the mounting portion to a plate 23D serving as the back flow preventing portion by welding. Alternatively, it may be manufactured by joining two L-shaped adjusting plates 23 of the first embodiment shown in FIG. 5 back to back by clamping.

Sixth Embodiment

[0097] FIG. 9 shows a detailed sectional view illustrating the vicinity of a fan ring in a cooling device according to a sixth embodiment of the invention.

[0098] The cooling device 10E of the sixth embodiment has an adjusting plate 23 of h-shaped (bifurcated) section. This adjusting plate 23 is formed by joining a flat plate 23E to another plate 23F by clamping with the mounting bolts 24, the plate 23F being bent into the shape of a crank. In this case, the fan ring 15 has only one projecting portion 16C and the section of the fan ring 15 is in the form of . This projecting portion 16C is positioned in the intermediate space of the bifurcated portion of the adjusting plate 23. It should be noted that the fan ring 15 is not necessarily limited to the shape described in this embodiment but may be in the form of that is constituted by not only the projecting portion 16C but also the projection portions 16A, 16B which are located at both axial ends as indicated by chain double-dashed line of FIG. 9.

[0099] Although the adjusting plate is equally divided into two in a circumferential direction in the foregoing embodiments, the adjusting plate is not necessarily limited to this but may be divided into three, four and so on and may be divided into unequal parts.

[0100] Although the fan ring 15 takes a form of U shape having the projecting portions 16A, 16B at both ends thereof in the foregoing embodiments, the fan ring 15 is not necessarily limited to this shape but may have one or a plurality of additional projecting portions between the projecting portions 16A, 16B formed at both ends, as illustrated in FIG. 9.

[0101] Although the invention has been particularly described with the case where the axial fan 12 is fixed to the engine 11 and the shroud 17 is fixed to the radiator 13 in the foregoing embodiments, it is not necessarily limited to such an arrangement but may be modified, for example, such that the shroud 17 and the axial fan 12 are fixedly attached to the radiator 13. In this case, the axial fan 12 may be driven by, for example, a hydraulic motor.

[0102] Although the invention has been particularly described with a suction-type cooling device in which the axial fan 12 suctions cooling air from the radiator 13, it is not necessarily limited to this but is equally applicable to a discharging-type in which the axial fan 12 discharges cooling air.

[0103] Industrial Applicability

[0104] The invention is applicable to cooling devices for the engine of heavy vehicles such as construction machines.

Claims

1. A cooling device comprising: (a) an axial fan having a plurality of vanes; (b) a power source for driving the axial fan; (c) a tubular fan ring disposed in outer edge portions of the vanes; (d) a projecting portion that extends over substantially entire circumference of the fan ring and projects in an outer peripheral direction; (e) a shroud disposed between the axial fan and an object to be cooled; and (f) an adjusting plate that is fixedly attached to the shroud so as to make a distance from an outer circumferential surface of the fan ring variable and circumferentially divided into a plurality of parts.

2. The cooling device according to claim 1, wherein the adjusting plate has an L-shaped section.

3. The cooling device according to claim 1, wherein the adjusting plate has a T-shaped section.

4. The cooling device according to claim 1, wherein the number of said projecting portions is at least two and an inner circumferential portion of the adjusting plate is positioned between any two of the projecting portions with respect to an axial direction of the axial fan.

5. The cooling device according to claim 4, wherein the adjusting plate is disposed so as to overlap the projecting portions of the fan ring when viewed in a front view of the axial fan.

6. The cooling device according to claim 1, wherein an inner circumferential portion of the adjusting plate is bifurcated and the projecting portion is located within intermediate space of the bifurcated portion.

7. The cooling device according to claim 6, wherein the adjusting plate is disposed so as to overlap the projecting portion of the fan ring when viewed in a front view of the axial fan.

8. The cooling device according to claim 2, wherein the number of said projecting portions is at least two and an inner circumferential portion of the adjusting plate is positioned between any two of the projecting portions with respect to an axial direction of the axial fan.

9. The cooling device according to claim 8, wherein the adjusting plate is disposed so as to overlap the projecting portions of the fan ring when viewed in a front view of the axial fan.

10. The cooling device according to claim 3, wherein the number of said projecting portions is at least two and an inner circumferential portion of the adjusting plate is positioned between any two of the projecting portions with respect to an axial direction of the axial fan.

11. The cooling device according to claim 10, wherein the adjusting plate is disposed so as to overlap the projecting portions of the fan ring when viewed in a front view of the axial fan.