JP5901907B2 - cooling fan - Google Patents

Description

  The present invention relates to a cooling fan used for, for example, a radiator of an automobile.

Most of this type of cooling fan is provided with a plurality of blades projecting radially outward at a boss portion connected to a rotational drive source such as an engine or an electric motor, and the blade is swung by the power of the rotational drive source. The basic structure is such that air is blown to the object to be cooled.
By the way, in such a cooling fan, each blade is formed so as to be inclined with respect to the rotation direction of the fan. When the cooling fan rotates, the vicinity of the surface facing the front in the rotation direction of each blade becomes positive pressure, while the vicinity of the surface facing the rear becomes negative pressure.

By the way, it is known that reducing the thickness of the blade is advantageous in increasing the fan efficiency. However, if the thickness of the blade is reduced, the blade is bent during rotation, and fluttering easily occurs.
For this reason, a cooling fan that achieves both suppression of flapping and thinning of the blade has been devised in which the vicinity of the radially outer ends of a plurality of blades is connected by a cylindrical ring member (for example, , See Patent Document 1).

International Publication No. 2008/072516

  Here, the surface that becomes positive pressure on each blade when the cooling fan rotates is called a positive pressure surface, and the surface that becomes negative pressure is called a negative pressure surface. A part of the air flowing along the surface tends to flow to the outside of the ring member due to inertial force after passing through the rear end in the rotation direction of the blade. Then, there is a problem that the air that has flowed to the outside of the ring member flows into the suction surface side, and the blade tip vortex generated at this time tends to increase the noise of the cooling fan.

  Accordingly, the present invention has been made in view of the above-described circumstances, and provides a cooling fan that can suppress noise generation.

The cooling fan according to the present invention employs the following means in order to solve the above problems.
According to a first aspect of the present invention, there is provided a boss portion coupled to a rotational drive source so that power can be transmitted, and a plurality of blades formed integrally with the boss portion and projecting radially outward from the boss portion. A ring member that annularly connects end regions on the radially outer side of the plurality of blades, and the plurality of blades have a forward wing shape in which the extended end side curves forward in the rotational direction, Furthermore, the edge on the front side in the rotational direction includes a bulging region in which the amount of bulging toward the front increases as the extension end is approached, and the axial end on the air discharge side of the ring member includes: A wall portion that extends outward in the axial direction from the general surface of the axial end portion on the air discharge side is provided at a location corresponding to the rear region in the rotational direction of the blade, and is provided on the air suction side of the ring member. Each said blur at the end in the axial direction Between the bulging region of the de, and in a position overlapping with the wall portion in the axial direction and is characterized in that a air inlet groove.

  The invention according to claim 2 is characterized in that the wall portion is bent and extended with a general surface of an axial end portion on the air discharge side of the ring member as a base point.

  The invention according to claim 3 is characterized in that an angle between the ring member and the wall portion is set in a range of 15 degrees to 30 degrees.

  The invention according to claim 4 is characterized in that the wall portion is disposed between a front region in the rotation direction of all blades on the ring member and a rear region in the rotation direction of adjacent blades. Is.

Invention, the end portion of the axial air discharge side of the front Symbol ring member, said to be shifted in the air inlet groove and the circumferential direction, and characterized in that lightening grooves is provided according to claim 5 To do.

  According to a sixth aspect of the present invention, when the height from the hollow groove to the general surface of the axial end portion of the ring member on the air suction side is h, the wall portion extends from the air inflow groove. The height to the tip is set in the range of 1.2h to 1.3h.

  According to a seventh aspect of the present invention, the wall portion is provided between a rear region in the rotation direction of all the blades on the ring member and the lightening groove formed at a position corresponding to each rear region. It is characterized by being.

  The invention according to claim 8 is characterized in that the connection position of the plurality of blades and the ring member is set at a position offset radially inward from the radially outer end of the blade. .

  According to the first aspect of the present invention, the wall portion is provided at the axial end portion on the air discharge side of the ring member at a position corresponding to the rear region in the blade rotation direction. Even after passing through the rear end in the rotational direction, air can be prevented from flowing out of the ring member. For this reason, generation | occurrence | production of the noise of a cooling fan can be suppressed.

  According to the second aspect of the present invention, the wall portion is bent and extended with the general surface of the axial end portion on the air discharge side of the ring member as a base point, thereby reducing the noise of the cooling fan without lowering the fan efficiency. Generation can be reliably suppressed.

  According to the third aspect of the present invention, the noise generation of the cooling fan can be effectively suppressed by regulating the angle of the wall portion.

  According to the invention described in claim 4, the weight balance in the circumferential direction of the cooling fan can be improved.

  According to the invention described in claim 5, the weight balance in the circumferential direction of the cooling fan can be further increased.

  According to the invention described in claim 6, the noise generation of the cooling fan can be effectively suppressed by restricting the axial height of the wall portion.

  According to the invention described in claim 7, even if the ring member has the lightening groove set while maintaining a good weight balance in the circumferential direction of the cooling fan, the wall portion coexists with the lightening groove. Can be laid out. For this reason, noise generation of the cooling fan can be suppressed while improving the degree of freedom in design.

  According to the eighth aspect of the present invention, it is possible to suppress an increase in the diameter of the cooling fan and to reduce the manufacturing cost.

It is a front view of the cooling fan in a 1st embodiment of the present invention. It is a perspective view of the fan main body of the cooling fan in 1st Embodiment of this invention. It is sectional drawing which follows the AA line of FIG. It is a typical side view of the fan main body of the cooling fan in 1st Embodiment of this invention. It is a graph which shows the result of having investigated the fan noise by changing the height of the wall part in 1st Embodiment of this invention. It is a perspective view of the fan main body of the cooling fan in 2nd Embodiment of this invention. It is sectional drawing which follows the BB line of FIG. It is explanatory drawing which shows the flow of the air to the fan main body in 2nd Embodiment of this invention. It is a graph which shows the result of having investigated the fan efficiency by changing the angle of the wall part in 2nd Embodiment of this invention. It is a perspective view of the fan main body of the cooling fan in 3rd Embodiment of this invention. It is a perspective view of the fan main body of the cooling fan in the reference example of this invention.

(First embodiment)
(cooling fan)
A first embodiment of the present invention will be described below with reference to FIGS.
1 is a front view of the cooling fan 1 according to the first embodiment, FIG. 2 is a perspective view showing a fan body 10 of the cooling fan 1, and FIG. 3 is a line AA in FIG. FIG.
The cooling fan 1 is an axial fan used for a radiator of an automobile. The fan body 10 is driven to rotate by a rotation drive source such as an engine or an electric motor (not shown), and the air to the radiator covers the outer peripheral side of the fan body 10 And a shroud 11 for improving the efficiency of introduction of the.

  The shroud 11 is provided with a circular air guide hole 30 having a depth depth along the axial direction of the fan main body 10 at the approximate center of the front surface thereof, and the fan main body 10 is located inside the peripheral wall surface of the air guide hole 30. It is arranged so that it can rotate. Moreover, the area | region surrounding the air guide hole 30 of the front surface of the shroud 11 is made into the taper surface 31 dented toward the air guide hole 30, as shown in FIG.

  The fan body 10 includes a bottomed cylindrical boss portion 12 connected to an output shaft of a rotational drive source, and a plurality of blades 13 (this first portion) projecting radially outward integrally with the outer peripheral surface of the boss portion 12. In the case of the embodiment, there are five blades, each of which is integrally formed with the outer peripheral surface of the boss portion 12.) and a cylindrical ring that connects the radially outer end regions of the plurality of blades 13 in an annular shape. And a member 14. The ring member 14 is in a state of annularly connecting positions offset radially inward from the radially outer end of the blade 13.

  Here, regarding the fan body 10, assuming that the surface exposed to the outside of the shroud 11 (the surface that can be seen from the front in FIG. 1) is referred to as the front surface, and the back surface thereof is referred to as the rear surface. 1 and FIG. 2 is inclined so that the front side in the rotation direction of the fan main body 10 indicated by the arrow R opens to the front side of the fan main body 10. Therefore, the rear surface side of the blade 13 is a pressure surface, and the front surface side of the blade 13 is a suction surface.

  In addition, each blade 13 is set such that the elevation angle is large on the root side and the chord length is short, and the elevation angle gradually decreases and the chord length gradually increases toward the extended end side. Has been. The extending end of each blade 13 is formed in an arc shape that draws a circle that is coaxial with the boss portion 12 in a front view, and a substantially constant minute gap is formed with respect to the inner peripheral surface of the air guide hole 30 of the shroud 11. To be maintained.

  Further, the blade 13 of the first embodiment has a forward wing shape in which the extended end side is curved toward the front in the rotational direction when viewed from the front, and in particular, the edge portion on the front side in the rotational direction extends. As it approaches the end, the amount of bulging forward increases. Hereinafter, the region where the bulge amount is large is referred to as “bulge region 13a”.

  The ring member 14 is provided with a plurality of air inflow grooves 16 at an axial end on the air suction side (front side of the fan main body 10), and an axial end on the air discharge side (rear surface side of the fan main body 10). Similarly, a plurality of lightening grooves 17 are formed in the part.

The general surface 14a at the axial end of the ring member 14 on the air suction side is formed at substantially the same height as the axial end of the blade 13 (the left end in FIG. 3). The bottom portion of 16 is formed to be depressed by a predetermined depth with respect to the general surface 14a. Each air inflow groove 16 is formed between the bulging area 13 a of one blade 13 and the bulging area 13 a of another blade 13 adjacent to the circumferential area of the ring member 14. The air inflow grooves 16 are provided at equal intervals in the circumferential area of the ring member 14.
In the first embodiment, the general surface 14a at the end of the ring member 14 in the axial direction on the air suction side is formed at substantially the same height as one end of the blade 13 in the axial direction. The height may be different from one end of the blade 13 in the axial direction.

Further, the general surface 14b of the axial end portion on the air discharge side of the ring member 14 is formed at substantially the same height as the other axial end portion (the right end portion in FIG. 3) of the blade 13. The bottom portion of the lightening groove 17 is formed to be recessed by a predetermined depth with respect to the general surface 14b. Each of the lightening grooves 17 is formed at a position facing the pressure surface of each blade 13 and at a position where at least the bottom thereof is offset on the ring member 14 from the bottom of the air inflow groove 16 in the circumferential direction. The respective hollow grooves 17 are provided at equal intervals in the peripheral area of the ring member 14.
In the first embodiment, the general surface 14b at the axial end of the ring member 14 on the air discharge side is also formed at substantially the same height as the other axial end of the blade 13. 14b may have a height different from the other end of the blade 13 in the axial direction.

Further, the air inflow groove 16 and the lightening groove 17 are not square-shaped grooves, but are formed in a trapezoidal shape having a slanted surface. Thereby, the ring member 14 can be easily molded when the fan body 10 is molded.
In the case of the first embodiment, the air inflow groove 16 and the lightening groove 17 are set to the same depth. However, the depths of the air inflow groove 16 and the lightening groove 17 are not necessarily the same.

Furthermore, a wall portion 42 extending along the axial direction is formed on the general surface 14b at the axial end of the ring member 14 on the air discharge side. The wall portion 42 is disposed between the rear region of the rotation direction of all the blades 13 (the direction of the arrow R in FIGS. 1 and 2) and the lightening groove 17 formed at a position corresponding to each rear region. ing. In other words, the wall portion 42 is an end portion on the air discharge side of the ring member 14 and is disposed at a position substantially overlapping with the air inflow groove 16 in the axial direction.
Further, the wall portion 42 is inclined so that both side surfaces in the circumferential direction are positioned on the extension line of the circumferential side surface of the lightening groove 17, and is formed in a tapered trapezoidal shape as a whole.

Next, a method for manufacturing the fan body 10 of the cooling fan 1 will be described.
The fan main body 10 is a resin molded product molded from a resin material such as polypropylene, and is formed by filling the upper and lower molds with a resin material. The upper mold is provided with a plurality of gates 41 (see the two-dot chain line in FIG. 1) for injecting a resin material (for example, seven locations in the first embodiment). The formation position of the gate 41 will be described in more detail. As shown in FIG. 1, the formation position of the bottom surface portion of the boss portion 12 is located at the root portion where the plurality of blades 13 are integrally provided.

After the upper and lower molds are matched, resin material melted in a high temperature state is injected from each gate 41, and the resin material is sequentially filled into the space where the boss portion 12 is formed and the space where the plurality of blades 13 are formed. Is done. Subsequently, the resin material is finally filled in the space in which the ring member 14 is formed. At this time, the resin material injected from the adjacent gates 41 is coupled in the vicinity of the center of the ring member 14 between the adjacent blades 13 through the spaces forming the blades 13.
As described above, the fan main body 10 of the cooling fan 1 is formed as having the joint portion (weld) W between the resins near the center of the ring member 14 between the adjacent blades 13 (two points in FIG. 2). (See chain line).

(Function)
Next, the behavior of air when the fan body 10 of the cooling fan 1 is rotationally driven will be described with reference to FIGS. FIG. 4 is a schematic side view of the fan main body 10 of the cooling fan 1.
As shown in FIGS. 3 and 4, when the fan body 10 of the cooling fan 1 is rotationally driven, air is mainly introduced from the front side of the air guide hole 30 of the shroud 11 as indicated by an arrow in FIG. 3. The air is sucked into the space between the air and the air, and the air is supplied to a radiator (not shown) disposed on the rear side of the fan body 10.

  At this time, air flows into the air guide hole 30 of the shroud 11 not only from the front side but also from the outer peripheral side of the shroud 11. The air flowing in from the outer peripheral side of the shroud 11 travels in the direction of the air guide hole 30 along the tapered surface 31 on the front surface of the shroud 11, and passes through the air inflow groove 16 provided in the ring member 14 of the fan body 10. It is sucked in between the blades 13 and discharged along the axial direction.

  Since the air flowing in from the outer peripheral side of the shroud 11 passes through the air inflow groove 16 lower than the general surface 14a at the end of the ring member 14 and is sucked in between the blades 13, the air flows in the ring member 14 portion. Without turning sharply, the direction is gradually changed in the axial direction. For this reason, in the case of this cooling fan 1, the flow velocity of the air flowing in from the outer peripheral side of the shroud 11 is not rapidly increased at the ring member 14 portion.

  On the other hand, the air that escapes to the air discharge side of the fan main body 10 (the rear surface side of the fan main body 10, the lower side in FIG. 4) is radially inward of the ring member 14 of the blade 13 and on the positive pressure surface inner side. , And flows along the blade 13. And air tends to flow to the outside of the ring member 14 due to inertial force after passing the edge on the rear side in the rotational direction.

Here, when the wall portion 42 is not formed on the ring member 14, the air flows outward in the radial direction of the ring member 14, and further flows into the negative pressure surface side of the fan body 10. In such a case, a blade tip vortex is generated, and the noise of the cooling fan 1 is increased.
However, since the wall portion 42 is formed at a predetermined position of the ring member 14, the air discharged from the blade 13 is obstructed by the wall portion 42 and is less likely to flow outward in the radial direction than the ring member 14.

(effect)
Therefore, in this cooling fan 1, it is possible to prevent the generation of noise due to the rapid increase in the air flow rate at the ring member 14 portion.
Further, in the case of this cooling fan 1, air flowing in from the outer peripheral side of the shroud 11 passes through the air inflow groove 16 portion where a sufficient air passage area is secured and is sucked between the blades 13 with the shortest distance. The air flow resistance is small, and it can be expected that fan efficiency is sufficiently improved.

  In the cooling fan 1, the air inflow groove 16 is disposed between the front region in the rotational direction of all the blades 13 on the ring member 14 and the front region in the rotational direction of the adjacent blade 13. Therefore, air can be efficiently and evenly sucked into the fan main body 10 from the outer peripheral side of the ring member 14, and the weight balance (rotation balance) in the circumferential direction of the fan main body 10 can be improved.

Further, in this cooling fan 1, since the hollowing groove 17 is provided at the axial end of the ring member 14 on the air discharge side so as to be displaced in the circumferential direction from the air inflow groove 16, The circumferential weight balance is better.
In particular, in the case of this first embodiment, the depth of the air inflow groove 16 and the thickness reduction groove 17 is set to the same depth, and the axial thickness of the ring member 14 is uniform over almost the entire area in the circumferential direction. Therefore, the weight balance in the circumferential direction of the ring member 14 is further improved.

In the cooling fan 1, the wall portion 42 extending along the axial direction is formed on the general surface 14 b of the axial end of the ring member 14 on the air discharge side. The generated air is obstructed by the wall 42 and is less likely to flow radially outward than the ring member 14. For this reason, the noise of the cooling fan 1 can be reduced more reliably.
Further, the wall portion 42 is between the rear region of the rotation direction of all the blades 13 (the direction of the arrow R in FIGS. 1 and 2) and the lightening groove 17 formed at a position corresponding to each rear region. Has been placed. Thus, even in the ring member 14 in which the lightening groove 17 is formed, the wall portion 42 can be laid out in coexistence with the lightening groove 17, and the degree of design freedom can be increased. .

Here, based on FIG. 4, FIG. 5, the experimental result which investigated the relationship between the height H of the wall part 42 formed in the ring member 14, and a fan noise is demonstrated.
In FIG. 4, h indicates the height from the lightening groove 17 to the general surface 14 a at the axial end of the ring member 14 on the air suction side. Further, the height H of the wall portion 42 means the height in the axial direction from the air inflow groove 16 to the tip of the wall portion 42. And the height of the wall part 42 was changed with the case of 1.2h, and the case of 1.3h, and the fan noise at that time was compared with the noise when there is no wall part 42 (current h).

FIG. 5 is a graph showing the experimental results at this time.
As is clear from the figure, when the height of the wall portion 42 is set in the range of 1.2 h to 1.3 h, the fan noise is reduced more favorably than when the wall portion 42 is not provided. Results were obtained.
Therefore, the height H of the wall portion 42 is 1.2 h to 1.3 h with respect to the height h from the lightening groove 17 to the general surface 14 a of the axial end portion on the air suction side of the ring member 14. It is desirable to be set within the range.

Here, when the fan body 10 of the cooling fan 1 is rotationally driven, the following event occurs between the adjacent blades 13.
2 and 4, when the fan body 10 rotates in the direction of the arrow R, the rear side of the blade 13 in the rotational direction is a stress (positive) that causes the passing air to flow toward the pressure surface side. Due to the force (suctioned to the pressure surface side), stress is received in the downward direction (pressure surface side) in the figure. On the other hand, since the front side in the rotational direction of the blade 13 cuts air and flows between the blades 13, it receives stress in the upward direction (negative pressure surface side) in the figure.
That is, the direction of the stress to be received is different between the front side and the rear side in the rotation direction of the blade 13, and a twisting stress is generated in the blade 13 as a whole. This stress is concentrated near the center of the ring member 14 connecting the blades 13.

By the way, in the process of manufacturing the fan body 10 described above, the temperature of the injected resin material is slightly lower at the time when it reaches the ring member 14 than when it is injected into the gate. For this reason, the strengths of the bonding sites W of the resins in the fan main body 10 (in this first embodiment, a total of five locations) may vary.
In view of such circumstances, it is necessary to increase the strength of the fan main body 10 so that the stress applied to the ring member 14 does not concentrate on the joint sites W of the resin of the ring member 14 when the fan main body 10 is rotationally driven. For this reason, it is also conceivable to use a high-quality resin material with high bonding strength, increase the thickness of the ring member 14, or increase the axial length.

However, if it does in this way, the resin material will become high or the usage-amount of resin will increase, As a result, the subject that the manufacturing cost of the fan main body 10 will increase occurs.
Generally, when the object has a shape change point (bending point) or the like, the stress acting on the object tends to be distributed on the change point side. Here, in the first embodiment, the air inflow groove 16 is provided on the air suction side of the ring member 14, and the lightening groove 17 is provided on the air discharge side. For this reason, the stress which acts can be disperse | distributed to the change point C vicinity (refer FIG. 2) of each groove | channel 16 and 17 with respect to the said subject. Therefore, the strength of the fan body 10 can be ensured without increasing the manufacturing cost.

(Second Embodiment)
Next, a second embodiment of the present invention will be described with reference to FIGS. The same aspects as those in the first embodiment will be described with the same reference numerals (the same applies to the following embodiments).
FIG. 6 is a perspective view showing the fan main body 210 of the cooling fan 201 of the second embodiment, and FIG. 7 is a cross-sectional view taken along the line BB of FIG.

  As shown in FIGS. 6 and 7, in the second embodiment, the cooling fan 201 is an axial fan used for a radiator of an automobile, and is rotationally driven by a rotational drive source such as an engine or an electric motor (not shown). The fan main body 210 is provided with a shroud (not shown in FIG. 6) for covering the outer peripheral side of the fan main body 210 and increasing the efficiency of introducing air to the radiator. A bottomed cylindrical boss portion 12 connected to the shaft, a plurality of blades 13 projecting radially outward integrally with the outer peripheral surface of the boss portion 12, and a radially outer end region of the plurality of blades 13 The basic configuration such as a cylindrical ring member 14 that connects the two in a ring shape is the same as that of the first embodiment described above (the same applies to the following embodiments).

Here, the difference between the second embodiment and the first embodiment is that the wall portion 42 of the first embodiment extends in the axial direction from the general surface 14b at the axial end of the ring member 14 on the air discharge side. The wall portion 43 of the second embodiment is formed so as to bend and extend so as to go obliquely outward with the general surface 14b of the ring member 14 as a base point.
That is, the wall portion 43 is provided in a state inclined obliquely outward with respect to the ring member 14 by an angle θ. For this reason, the ring member 14 is formed in a divergent shape toward the air discharge side, and the opening area gradually increases from the air suction side toward the air discharge side.

FIG. 8 is an explanatory diagram showing the air flow when the fan main body 210 of the cooling fan 201 is driven to rotate.
As shown in the figure, in the configuration as described above, when the fan main body 210 of the cooling fan 201 is driven to rotate, air flows between the blades 13 from the air suction side of the cooling fan 201 (the back side in FIG. 8). The air is sucked into the space, and the air escapes to the air discharge side of the fan main body 210 (the front side in FIG. 8). At this time, since the opening area of the ring member 14 gradually increases toward the air discharge side, the flow rate of the discharged air becomes slower on the air discharge side of the ring member 14. Thereby, the air pressure by the cooling fan 201 can be increased.

Therefore, in the cooling fan 201, in addition to the same effects as those of the first embodiment described above, the air pressure by the cooling fan 201 can be increased, so that fan efficiency can be improved.
Here, it is desirable that the angle θ between the ring member 14 and the wall portion 43 is set in a range of 15 degrees to 30 degrees. This will be described in more detail with reference to FIG.
FIG. 9 is a graph of experimental results obtained by examining the fan efficiency by changing the angle θ of the wall 43.
As shown in the figure, when the angle θ is set in the range of 15 degrees to 30 degrees, the fan efficiency is improved as compared with the conventional case where there is no wall portion 43 (corrugated ring). I can confirm.

(Third embodiment)
Next, a third embodiment of the present invention will be described with reference to FIG.
FIG. 10 is a perspective view showing the fan main body 310 of the cooling fan 301 of the third embodiment.
As shown in the figure, the difference between the fan main body 310 of the third embodiment and the fan main body 10 of the first embodiment is that the ring member 14 of the first embodiment has an end on the radially outer side of the blade 13. The ring member 14 of the third embodiment is in a state in which the radially outer end portion of the blade 13 is connected in an annular shape, whereas the position offset radially inward from the portion is in an annularly connected state. There is in point.

  The wall portion 44 formed to extend to the air discharge side of the ring member 14 is disposed between the blades 13 adjacent to each other in the circumferential direction, that is, in the rear region of the rotation direction of all the blades 13 (arrow R direction in FIG. 10). Has been. Furthermore, in other words, the wall portion 44 is disposed between the front region in the rotational direction of all the blades 13 and the rear region in the rotational direction of the adjacent blades. Similar to the wall portion 42 of the first embodiment described above, the wall portion 44 is formed in a tapered trapezoidal shape having an inclined surface, not a wall in a plan view. Thereby, the ring member 14 can be easily molded when the fan body 10 is molded.

Therefore, in the cooling fan 301, in addition to the same effects as those of the first embodiment described above, air suction and discharge can be controlled using the entire blade 13, and the noise of the cooling fan 1 can be prevented more effectively. In addition, the fan efficiency can be improved.
In addition, an increase in the diameter of the entire cooling fan 301 can be suppressed, and the manufacturing cost can be reduced.

( Reference example )
Next, a reference example of the present invention will be described with reference to FIG.
FIG. 11 is a perspective view showing the fan body 410 of the cooling fan 401 of this reference example .
As shown in the figure, the difference between the fan main body 410 of this reference example and the fan main body 310 of the third embodiment is that the ring member 14 of the third embodiment has an air inflow groove 16 and a lightening groove. 17 is formed, whereas the ring member 414 of the reference example is not formed with the air inflow groove 16 and the lightening groove 17 but only the wall portion 45 is formed.

The wall portion 45 is disposed between the blades 13 adjacent to each other in the circumferential direction, that is, in the rear region of the rotation direction of all the blades 13 (the direction of the arrow R in FIG. 11). Furthermore, in other words, the wall portion 44 is disposed between the front region in the rotational direction of all the blades 13 and the rear region in the rotational direction of the adjacent blades. Similar to the wall portion 42 of the first embodiment described above, the wall portion 44 is formed in a tapered trapezoidal shape having an inclined surface, not a wall in a plan view. Thereby, the ring member 14 can be easily molded when the fan body 10 is molded.
Even in this case, the air discharged from the blade 13 is obstructed by the wall 45 and is less likely to flow outward in the radial direction than the ring member 14. For this reason, the noise of the cooling fan 401 can be reduced reliably.

In addition, this invention is not limited to said embodiment, A various design change is possible in the range which does not deviate from the summary.
For example, in the above embodiment, the cooling fan is used for cooling the radiator, but the cooling fan according to the present invention is not limited to the radiator cooling, and may be used for cooling other devices. Good.

1, 201, 301, 401 ... Cooling fan 12 ... Boss part 13 ... Blade
13a ... bulging area 14,414 ... ring member 14a, 14b ... general surface 16 ... air inflow groove 17 ... thickening groove 42,43,44,45 ... wall

Claims (8)

A boss connected to a rotational drive source so that power can be transmitted;
A plurality of blades formed integrally with the boss portion and projecting radially outward from the boss portion;
A ring member that annularly connects the radially outer end regions of the plurality of blades,
The plurality of blades have a forward wing shape in which the extended end side curves toward the front in the rotational direction, and the edge on the front side in the rotational direction bulges forward as the extension end approaches the extended end. With a bulging area where
An axial end portion of the ring member on the air discharge side extends outward in the axial direction from a general surface of an axial end portion on the air discharge side at a position corresponding to a rear region in the rotation direction of the blade. A protruding wall is provided,
Cooling, characterized in that an air inflow groove is provided between the bulging areas of the blades at the axial end of the ring member on the air suction side and at the position overlapping the wall portion in the axial direction. fan.   The cooling fan according to claim 1, wherein the wall portion is bent and extended with a general surface of an axial end portion of the ring member on the air discharge side as a base point.   The cooling fan according to claim 2, wherein an angle between the ring member and the wall portion is set in a range of 15 degrees to 30 degrees.   The said wall part is arrange | positioned between the front part area | region of the rotation direction of all the blades on the said ring member, and the rear part area | region of the rotation direction of an adjacent braid | blade. The cooling fan according to item 1.   5. A lightening groove is provided at an axial end of the ring member on the air discharge side so as to be displaced in the circumferential direction from the air inflow groove. The cooling fan according to item 1. When the height from the hollow groove to the general surface of the axial end of the ring member on the air suction side is h,
The cooling fan according to claim 5 , wherein a height from the air inflow groove to a tip of the wall portion is set in a range of 1.2 h to 1.3 h.   The wall portion is provided between a rear region in the rotation direction of all the blades on the ring member and the lightening groove formed at a position corresponding to each rear region. The cooling fan according to claim 5.   8. The connection position of the plurality of blades and the ring member is set to a position offset radially inward from the radially outer end of the blade. The listed cooling fan.

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