FORM 2
THE PATENTS ACT 1970

(39of 1970)
&
The Patents Rules, 2003
COMPLETE SPECIFICATION
(See section 10 and rule 13)
1. VEHICULAR AIR CONDITIONING SYSTEM

Technical Field
The present invention relates to a vehicular air conditioning system, and more particularly, a vehicular air conditioning system in which foreign substance capture protrusions having three or more surfaces are formed on the hub portion of a blower fan corresponding to the cooling air discharge side of a blower motor to capture fine foreign substances contained in the cooling air for the blower motor, thereby making it possible to improve the capture efficiency of fine foreign substances in the cooling air and consequently preventing the fine foreign substances in the cooling air for the blower motor from flowing into an air conditioning case and a vehicle interior.
Background Art
A motor vehicle is equipped with an air conditioning system that cools and heats a vehicle interior. As shown in FIGS. 1 and 2, the air conditioning system includes a blower 10 that sucks the inside and outside air and blows the air into the vehicle interior.
The blower 10 includes a scroll casing 12, a blower fan 20 installed in a blowing chamber 14 of the scroll casing 12, and a blower motor 30 for driving the blower fan 20.
The blower fan 20 is a multi-vane fan, and includes a central cone-type hub 22 and a plurality of vanes 24 installed around the hub 22.
In particular, the hub 22 is fixed to the shaft 36a of the blower motor 30, and the vanes 24 are rotated together with the hub 22 to suck the air at the inlet 12a of the scroll casing 12 and blow the sucked air toward the outlet 12b of the scroll casing 12.

The blower motor 30 includes a motor housing 32, stators 34 installed on the inner circumferential surface of the motor housing 32 at regular intervals along the circumferential direction, a rotor 36 rotatably installed inside the stators 34, commutators 37 installed at regular intervals on the outer surface of the motor shaft 36a of the rotor 36, and brushes 38 for intermittently applying an electric current to each of the commutators 37.
The motor housing 32 is formed by a combination of a front housing 32a and a rear housing 32b, and the motor housing 32 thus formed is fixedly installed on the scroll casing 12 through a peripheral motor cover 32c.
In this blower motor 30, when an electric current is applied to the commutators 37 through the brushes 38, the coils of the rotor 36 are excited and deexcited by the applied electric current to generate an attractive force and a repulsive force between the rotor 36 and the stators 34. The rotor 36 is rotated by the rotation torque generated by the attractive force and the repulsive force, and the blower fan 20 installed on the motor shaft 36a is rotated by the rotor 36.
Meanwhile, the blower 10 further includes a motor cooling device 40 for cooling the blower motor 30.
The motor cooling device 40 includes a cooling air supply path 42 for extracting the air on the side of the scroll casing 12 discharged from the blower fan 20 and supplying the air into the blower motor 30, and a plurality of cooling air discharge holes 44 for discharging the air supplied into the blower motor 30.
Since the motor cooling device 40 extracts a part of the air

discharged from the blower fan 20 and supplies the air into the blower motor 30, the air supplied into the blower motor 30 can cool various friction contact parts in the blower motor 130, thereby preventing the blower motor 30 from being overheated.
Meanwhile, the air that has cooled the inside of the blower motor 30 is discharged to the outside through the cooling air discharge holes 44. In particular, the air is discharged to the blowing chamber 14 of the scroll casing 12.
Typically, the cooling air supply path 42 is connected to the rear housing 32b of the motor housing 32, and the cooling air discharge holes 44 are formed in the front housing 32a of the motor housing 32.
In particular, the cooling air discharge holes 44 are formed in the portion of the front housing 32a of the motor housing 32 corresponding to the lower surface 22a of the hub 22 of the blower fan 20.
However, in this conventional air conditioning system, during the course of cooling the blower motor 30 through the use of the cooling air for the motor cooling device 40, various fine foreign substances generated inside the blower motor 30 are contained in the cooling air. The various fine foreign substances may flow into the scroll casing 12 through the cooling air discharge holes 44.
In particular, a large amount of copper powder is generated at various frictional contact parts inside the blower motor 30, for example, the frictional contact parts of the commutators 37 and the brushes 38. The copper powder is included in the cooling air supplied into the blower motor 30 and is introduced into the scroll casing 12 through the cooling air discharge holes 44.

The copper powder introduced into the scroll casing 12 adheres to various parts, for example, an evaporator (not shown), a heater core (not shown) and the like, which are installed in the air flow path of the air conditioning case (not shown), thereby corroding the heat exchanger. In addition, the air containing the copper powder is blown into the vehicle interior, consequently contaminating the air in the vehicle interior.
In particular, when the copper powder adheres to the heat exchanger, the corrosion of the heat exchanger is accelerated. The durability of the heat exchanger is significantly reduced due to the corrosion of the heat exchanger.
Under these circumstances, a number of techniques for removing and processing various fine foreign substances contained in the cooling air for the blower motor 30 have been proposed. One example thereof is a "centrifugal multi-vane blower" disclosed in Japanese Patent Application No. 2014-51818.
This technique adopts a structure in which a concave-convex portion is formed on the main plate of an impeller corresponding to the cooling air discharge holes of the electric motor.
This conventional technique is configured so that the fine foreign substances in the cooling air discharged from the cooling air discharge holes of the electric motor are captured by the concave-convex portion.
In this way, the fine foreign substances in the cooling air for the electric motor are removed and processed, thereby preventing the fine foreign substances generated in the electric motor from flowing into the scroll casing 12 and the vehicle interior.
However, this conventional technique has a disadvantage in that

the capture efficiency of fine foreign substances contained in the cooling air for the electric motor is low.
In particular, the annular concave-convex portion formed on the main plate of the impeller has two surface portions. However, these two surface portions cannot effectively capture the fine foreign substances contained in the cooling air for the electric motor.
Therefore, the fine foreign substances contained in the cooling air for the electric motor may still flow into the scroll casing and the vehicle interior.
Summary
In view of the problems inherent in the related art, it is an object of the present invention to provide a vehicular air conditioning system capable of significantly improving the capture efficiency of various fine foreign substances contained in cooling air for a blower motor through structural improvement.
Another object of the present invention is to provide a vehicular air conditioning system capable of preventing various fine foreign substances in a blower motor from flowing into a scroll casing through cooling air.
A further object of the present invention is to provide a vehicular air conditioning system capable of preventing corrosion of various air conditioning parts and air pollution in the vehicle interior due to the inflow of fine foreign substances into a scroll casing.
In order to achieve these objects, there is provided a vehicular air conditioning system, including: a blower fan; a blower motor configured to drive the blower fan; and a motor cooling device configured to cool the

blower motor, wherein the motor cooling device includes a cooling air supply path for extracting cooling air for the blower fan and supplying the cooling air into the blower motor, and a plurality of cooling air discharge holes for discharging the cooling air supplied into the blower motor, the blower fan includes a central hub fitted to a motor shaft of the blower motor, and a plurality of vanes installed at regular intervals along a circumference of the hub, the cooling air discharge holes of the blower motor are formed in a portion of the blower motor corresponding to the hub of the blower fan, and a surface area increasing part for increasing the surface area of the hub is formed in a portion of the hub of the blower fan corresponding to the cooling air discharge holes.
In the above system, the cooling air discharged from the cooling air discharge holes may be discharged along a cooling air discharge path between the hub of the blower fan and the blower motor, and the surface area increasing part may include a plurality of foreign substance capture protrusions formed in a portion of the hub of the blower fan corresponding to the cooling air discharge path so as to have three or more surfaces, respectively, and configured to capture fine foreign substances in the cooling air discharged from the cooling air discharge holes.
In the above system, the foreign substance capture protrusions may be formed on the hub of the blower fan to have four surfaces, respectively.
In the above system, the foreign substance capture projections may protrude from the hub of the blower fan to have four surfaces so that first two surfaces face each other and second two surfaces face each other, the first two surfaces meet with each other at the end portions

thereof to form a tip portion, and the second two surfaces are formed on both sides with respect to the tip portion, so that the foreign substance capture projections protrude in a triangular shape at a uniform thickness as a whole.
In the above system, the foreign substance capture protrusions each having four surfaces may be formed so that the area of each of the four surfaces is smaller than the area of a base surface of each of the foreign substance capture protrusions on the side of the hub.
In the above system, the foreign substance capture protrusions each having four surfaces may be configured so that an edge of the tip portion constituted by two of the four surfaces is formed in a direction perpendicular to a flow direction of the cooling air.
According to the vehicular air conditioning system of the present invention, the foreign substance capture protrusions having three or more surfaces are formed on the lower surface of the hub of the blower fan. Accordingly, it is possible to significantly increase the surface area of the lower surface of the hub of the blower fan.
Further, since the surface area of the lower surface of the hub of the blower fan can be significantly increased, it is possible to effectively capture the fine foreign substances in the cooling air for the blower motor discharged toward the lower surface of the hub of the blower fan.
Moreover, since the capture efficiency of the fine foreign substances in the cooling air for the blower motor discharged toward the lower surface of the hub of the blower fan can be improved, it is possible to reliably prevent the fine foreign substances in the cooling air for the blower motor from being introduced into the scroll casing.

In addition, since the fine foreign substances in the cooling air for the blower motor can be reliably prevented from being introduced into the scroll casing, it is possible to reliably suppress the corrosion of various air conditioning parts and the air pollution in the vehicle interior due to the introduction of fine copper powder into the scroll casing.
Brief Description of the Drawings
FIG. 1 is a view showing a conventional vehicular air conditioning system.
FIG. 2 is an enlarged view showing a blower constituting the conventional vehicular air conditioning system.
FIG. 3 is a view showing the configuration of a vehicular air conditioning system according to the present invention.
FIG. 4 is a bottom perspective view of a blower fan showing a surface area increasing part of the blower fan constituting the vehicular air conditioning system according to the present invention.
FIG. 5 is a bottom view of the blower fan showing the surface area increasing part of the blower fan constituting the vehicular air conditioning system according to the present invention.
FIG. 6 is a side sectional view showing a modification of the surface area increasing part of the blower fan constituting the vehicular air conditioning system according to the present invention.
Detailed Description
A preferred embodiment of a vehicular heat management system according to the present invention will now be described in detail with

reference to the accompanying drawings. The same components as those of the prior art described earlier will be designated by the same reference numerals.
Prior to describing the features of the vehicular air conditioning system according to the present invention, the blower 10 of the vehicular air conditioning system will be briefly described with reference to FIGS. 3 and 4.
The blower 10 includes a scroll casing 12, a blower fan 20 installed in a blowing chamber 14 of the scroll casing 12, and a blower motor 30 for driving the blower fan 20.
The blower fan 20 is a multi-vane fan, and includes a central cone-type hub 22 and a plurality of vanes 24 installed around the hub 22.
The blower motor 30 includes a motor housing 32, stators 34 installed on the inner circumferential surface of the motor housing 32 at regular intervals along the circumferential direction, a rotor 36 rotatably installed inside the stators 34, commutators 37 installed at regular intervals on the outer surface of the motor shaft 36a of the rotor 36, and brushes 38 for intermittently applying an electric current to each of the commutators 37.
The motor housing 32 is formed by a combination of a front housing 32a and a rear housing 32b, and the motor housing 32 thus formed is fixedly installed on the scroll casing 12 through a peripheral motor cover 32c.
Meanwhile, the blower 10 further includes a motor cooling device 40 for cooling the blower motor 30. The motor cooling device 40 includes a cooling air supply path 42 for extracting the air on the side of the scroll

casing 12 discharged from the blower fan 20 and supplying the air into the blower motor 30, and a plurality of cooling air discharge holes 44 for discharging the air supplied into the blower motor 30.
The motor cooling device 40 extracts a part of the air discharged from the blower fan 20 and supplies the air into the blower motor 30. Therefore, the air supplied into the blower motor 30 cools various friction contact parts in the blower motor 130.
Meanwhile, the air that has cooled the inside of the blower motor 30 is discharged toward the blowing chamber 14 of the scroll casing 12 through the cooling air discharge holes 44.
Typically, the cooling air supply path 42 is connected to the rear housing 32b of the motor housing 32, and the cooling air discharge holes 44 are formed in the front housing 32a of the motor housing 32.
In particular, the cooling air discharge holes 44 are formed in the portion of the front housing 32a around the motor shaft 36a along the circumferential direction.
In addition, the cooling air discharge holes 44 are formed in the portion of the front housing 32a of the motor housing 32 corresponding to the lower surface 22a of the hub 22 of the blower fan 20.
Accordingly, the air that has cooled the inside of the blower motor 30 is discharged from the cooling air discharge holes 44 and is then discharged toward the blowing chamber 14 of the scroll casing 12 along the flow path 26 (hereinafter referred to as a “cooling air discharge path 26”) between the blower motor 30 and the hub 22 of the blower fan 20 while colliding with the lower surface 22a of the hub 22 of the blower fan 20.

Next, the features of the vehicular air conditioning system according to the present invention will be described in detail with reference to FIGS. 3 to 5.
Referring first to FIGS. 3 to 5, the air conditioning system according to the present invention includes a surface area increasing part 50 for increasing the surface area of the hub 22 of the blower fan 20 on the blower motor 30 side.
The surface area increasing part 50 is configured to increase the surface area of the portion of the hub 22 of the blower fan 20 on the side of the blower motor 30 corresponding to the cooling air discharge holes 44 of the blower motor 30.
In particular, the surface area increasing part 50 is configured to increase the surface area of the portion of the hub 22 of the blower fan 20 on the side of the blower motor 30 corresponding to the cooling air discharge path 26 between the blower motor 30 and the hub 22 of the blower fan 20.
The surface area increasing part 50 includes a plurality of foreign substance capture protrusions 52 formed on the lower surface 22a of the hub 22 in the portion of the hub 22 of the blower fan 20 corresponding to the cooling air discharge path 26 of the blower motor.
Each of the foreign substance capture protrusions 52 is formed to protrude from the lower surface 22a of the hub 22 of the blower fan 20 so as to have three or more surfaces 52a, 52b, 52c and 52d.
The foreign substance capture protrusions 52 serve to capture fine foreign substances in the cooling air discharged from the cooling air discharge holes 44 of the blower motor 30 and then flowing along the

cooling air discharge path 26 between the blower motor 30 and the hub 22 of the blower fan 20.
Specifically, the foreign substance capture protrusions 52 capture various fine foreign substances generated in the internal friction contact portions of the blower motor 30 and contained in the cooling air, for example, a large amount of copper powder generated in the friction contact portions of the commutators 37 and the brushes 38.
Therefore, the copper powder generated between the commutators 37 and the brushes 38 is prevented from flowing directly into the scroll casing 12 through the cooling air discharge holes 44 of the motor housing 32 while flowing together with the cooling air.
Accordingly, it is possible to prevent corrosion of various air conditioning parts and air pollution in the vehicle interior due to the introduction of fine copper powder into the scroll casing 12. In particular, it is possible to prevent corrosion of the heat exchanger due to the introduction of fine copper powder and resultant deterioration of the durability of the heat exchanger.
In addition, since the foreign substance capture protrusions 52 protrude to have three or more surfaces 52a, 52b, 52c and 52d on the lower surface 22a of the hub 22 of the blower fan 20, the surface area of the hub 22 of the blower fan 20 on the side of the cooling air discharge path 26 is significantly increased.
Accordingly, it is possible to remarkably improve the capture efficiency of fine foreign substances in the cooling air flowing along the cooling air discharge path 26 after being discharged from the cooling air discharge holes 44 of the blower motor 30.

In this way, it is possible to reliably suppress the introduction of fine foreign substances in the cooling air for the blower motor 30 into the scroll casing 12, thereby reliably suppressing corrosion of various air conditioning parts and air pollution in the vehicle interior due to the introduction of fine copper powder into the scroll casing 12.
Preferably, the foreign substance capture protrusions 52 protrude from the lower surface 22a of the hub 22 of the blower fan 20 so as to have four surfaces 52a, 52b, 52c and 52d as shown in FIGS. 3 to 5.
More preferably, the foreign substance capture projections 52 protrude from the lower surface 22a of the hub 22 of the blower fan 20 to have four surfaces 52a, 52b, 52c and 52d so that first two surfaces 52a and 52b face each other and second two surfaces 52c and 52d face each other. The first two surfaces 52a and 52b meet with each other at the end portions thereof to form a tip portion 52e, and the second two surfaces 52c and 52d are formed on both sides with respect to the tip portion 52e so that the foreign substance capture projections 52 protrude in a triangular shape at a uniform thickness as a whole.
In addition, the triangular foreign substance capture protrusions 52 having four surfaces 52a, 52b, 52c and 52d are configured so that the area of each of the four surfaces 52a, 52b, 52c and 52d is smaller than the area of the base surface 52f of each of the foreign substance capture protrusions 52 on the side of the hub 22.
The reason for adopting this configuration is that, when the area of each of the four surfaces 52a, 52b, 52c and 52d is larger than the area of the base surface 52f of each of the foreign substance capture protrusions 52, the size of the foreign substance capture protrusions 52 may become

excessively large, thereby generating air resistance.
Further, in the foreign substance capture protrusions 52 protruding from the lower surface 22a of the hub 22 of the blower fan 20 so as to have four surfaces 52a, 52b, 52c and 52d, it is preferable that the tip portion 52e of the two surfaces 52a and 52b is oriented in a direction opposite to the flow direction of the cooling air. In particular, it is preferable that the edge of the tip portion 52e of the two surfaces 52a and 52b is formed in a direction perpendicular to the flow direction of the cooling air.
This is because, when the tip portion 52e of the two surfaces 52a and 52b is formed in a direction perpendicular to the flow direction of the cooling air, the foreign substance capture protrusions 52 can efficiently capture various fine foreign substances contained in the cooling air.
Further, in the foreign substance capture protrusions 52 having four surfaces 52a, 52b, 52c and 52d, the two surfaces 52a and 52b constituting the tip portion 52e are preferably formed to be perpendicular to each other. This is to assure that various fine foreign substances contained in the cooling air can be captured in a more efficient manner.
In addition, the foreign substance capture protrusions 52 on the lower surface 22a of the hub 22 of the blower fan 20 are formed in a dot pattern at regular intervals on a concentric circle about the shaft hole 22b of the hub 22 into which the motor shaft 36a of the blower motor 30 is fitted.
In particular, it is preferable that the foreign substance capture protrusions 52 are formed in a dot pattern at regular intervals on a plurality of concentric circles about the shaft hole 22b of the hub 22.

Accordingly, the foreign substance capture protrusions 52 are arranged in multiple rows radially outward from the shaft hole 22b of the hub 22.
In addition, the foreign substance capture projections 52 arranged in multiple rows radially outward from the shaft hole 22b of the hub 22 stagger from each other.
Accordingly, the foreign substance capture protrusions 52 are arranged in a zigzag form radially outward about the shaft hole 22b of the hub 22.
The reason for adopting this configuration is to make sure that the space on the side of the hub 22 of the blower fan 20 formed between the foreign substance capture protrusions 52 can be maintained in a zigzag shape. By doing so, the flow path of the cooling air can be made as complicated as possible, which makes it possible to efficiently capture various fine foreign substances contained in the cooling air.
It is preferable that the foreign substance capture protrusions 52 protruding from the lower surface 22a of the hub 22 of the blower fan 20 are not formed in a specific section (A) of the lower surface 22a of the hub 22.
Specifically, it is preferable that the foreign substance capture protrusions 52 are not formed in the portion of the lower surface 22a of the hub 22 where the cooling air discharge path 26 between the hub 22 of the blower fan 20 and the blower motor 30 is narrowest.
The reason is that when the foreign substance capture protrusions 52 are formed in the narrowest portion of the cooling air discharge path 26, the cooling air discharge path 26 may hinder the discharge of the cooling

air.
FIG. 6 is a diagram showing a modification of the surface area increasing part 50.
The surface area increasing part 50 according to a modification includes a plurality of foreign substance capture protrusions 52 formed on the lower surface 22a of the hub 22 of the blower fan 20. Each of the foreign substance capture protrusions 52 protrude to have four surfaces 52a, 52b, 52c, 52d and 52e.
More specifically, each of the foreign substance capture projections 52 is configured to protrude in a quadrangular shape as a whole from the lower surface 22a of the hub 22 of the blower fan 20 so as to have five surfaces 52a, 52b, 52c, 52d and 52e.
In each of the foreign substance capture protrusions 52 formed on the lower surface 22a of the hub 22 of the blower fan 20 to have five surfaces 52a, 52b, 52c, 52d and 52e, it is preferable that the four surfaces 52a, 52b, 52c, and 52d are formed in pairs in a horizontally corresponding relationship, and the remaining one surface 52e is formed to connect the end portions of the four surfaces 52a, 52b, 52c and 52d while making a right angle with respect to the four surfaces 52a, 52b, 52c and 52d. Thus, each of the foreign substance capture protrusions 52 is configured to protrude in a quadrangular shape at a uniform thickness as a whole.
In this regard, it is preferable that the one surface 52e connecting the end portions of the four surfaces 52a, 52b, 52c and 52d is formed in parallel with the lower surface 22a of the hub 22 of the blower fan 20.
The quadrangular foreign substance capture protrusions 52 having such a structure maximize the surface area of the hub 22 of the

blower fan 20 on the side of the cooling air discharge path 26.
Accordingly, the quadrangular foreign substance capture protrusions 52 maximizes the capture efficiency of fine foreign substances in the cooling air flowing along the cooling air discharge path 26 after being discharged from the cooling air discharge holes 44 of the blower motor 30.
In this way, it is possible to reliably suppress the introduction of fine foreign substances in the cooling air for the blower motor 30 into the scroll casing 12, thereby reliably suppressing corrosion of various air conditioning parts and air pollution in the vehicle interior due to the introduction of fine copper powder into the scroll casing 12.
According to the vehicular air conditioning system of the present invention having such a configuration, the foreign substance capture protrusions 52 having three or more surfaces 52a, 52b, 52c and 52d are formed on the lower surface 22a of the hub 22 of the blower fan 20. Accordingly, it is possible to significantly increase the surface area of the lower surface 22a of the hub 22 of the blower fan 20.
Further, since the surface area of the lower surface 22a of the hub 22 of the blower fan 20 can be significantly increased, it is possible to effectively capture the fine foreign substances in the cooling air for the blower motor 30 discharged toward the lower surface 22a of the hub 22 of the blower fan 20.
Moreover, since the capture efficiency of the fine foreign substances in the cooling air for the blower motor 30 discharged toward the lower surface 22a of the hub 22 of the blower fan 20 can be improved, it is possible to reliably prevent the fine foreign substances in the cooling

air for the blower motor 30 from being introduced into the scroll casing 12.
In addition, since the fine foreign substances in the cooling air for the blower motor 30 can be reliably prevented from being introduced into the scroll casing 12, it is possible to reliably suppress the corrosion of various air conditioning parts and the air pollution in the vehicle interior due to the introduction of fine copper powder into the scroll casing 12.
While the preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments. Various modifications and changes may be made without departing from the scope and spirit of the present invention defined in the claims.

We Claim:-
1. A vehicular air conditioning system, comprising:
a blower fan;
a blower motor configured to drive the blower fan; and
a motor cooling device configured to cool the blower motor,
wherein the motor cooling device includes a cooling air supply path for extracting a cooling air for the blower fan and supplying the cooling air into the blower motor, and a plurality of cooling air discharge holes for discharging the cooling air supplied into the blower motor,
the blower fan includes a central hub fitted to a motor shaft of the blower motor, and a plurality of vanes installed at regular intervals along a circumference of the hub,
the cooling air discharge holes of the blower motor are formed in a portion of the blower motor corresponding to the hub of the blower fan, and
a surface area increasing part for increasing the surface area of the hub is formed in a portion of the hub of the blower fan corresponding to the cooling air discharge holes.
2. The system of claim 1, wherein the cooling air discharged from the
cooling air discharge holes is discharged along a cooling air discharge path between the hub of the blower fan and the blower motor, and
the surface area increasing part includes a plurality of foreign substance capture protrusions formed in a portion of the hub of the blower fan corresponding to the cooling air discharge path so as to have three or more surfaces, respectively, and configured to capture fine foreign

substances in the cooling air discharged from the cooling air discharge holes.
3. The system of claim 2, wherein the foreign substance capture protrusions are formed on the hub of the blower fan to have four surfaces, respectively.
4. The system of claim 3, wherein the foreign substance capture projections protrude from the hub of the blower fan to have four surfaces so that first two surfaces face each other and second two surfaces face each other, the first two surfaces meet with each other at the end portions thereof to form a tip portion, and the second two surfaces are formed on both sides with respect to the tip portion, so that the foreign substance capture projections protrude in a triangular shape at a uniform thickness as a whole.
5. The system of claim 4, wherein the foreign substance capture protrusions each having four surfaces are formed so that the area of each of the four surfaces is smaller than the area of a base surface of each of the foreign substance capture protrusions on the side of the hub.
6. The system of claim 5, wherein the foreign substance capture protrusions each having four surfaces are configured so that an edge of the tip portion constituted by two of the four surfaces is formed in a direction perpendicular to a flow direction of the cooling air.

7. The system of claim 6, wherein the foreign substance capture protrusions each having four surfaces are configured so that the two surfaces constituting the tip portion are formed to have a right angle with respect to each other.
8. The system of claim 2, wherein the foreign substance capture protrusions are formed on the hub of the blower fan to have five surfaces, respectively.
9. The system of claim 8, wherein the foreign substance capture protrusions each having five surfaces formed on the hub of the blower fan are configured so that four of the five surfaces are formed in pairs in a horizontally corresponding relationship, the remaining one of the five surfaces is formed to connect end portions of the four surfaces while making a right angle with respect to the four surfaces, and each of the foreign substance capture protrusions protrudes in a quadrangular shape at a uniform thickness as a whole.
10. The system of claim 9, wherein the remaining one of the five surfaces connecting the end portions of the four surfaces is formed in parallel with the hub of the blower fan.
11. The system of any one claim of 2 to 10, wherein the foreign substance capture protrusions on the hub of the blower fan are formed at regular intervals on a concentric circle about a shaft hole of the hub into which a motor shaft of the blower motor is fitted.

12. The system of claim 11, wherein the foreign substance capture protrusions are arranged at regular intervals on a plurality of concentric circles arranged radially outward from the shaft hole of the hub.
13. The system of claim 12, wherein the foreign substance capture projections formed on the plurality of concentric circles are arranged to stagger from each other, and are arranged in a zigzag form radially outward about the shaft hole of the hub.
14. The system of claim 13, wherein the foreign substance capture protrusions on the hub of the blower fan are not formed in a specific section of the hub.
15. The system of claim 14, wherein the foreign substance capture protrusions are not formed in a portion of the hub where the cooling air discharge path between the hub and the blower motor is narrowest.