Cooling fan and fan device

Abstract

To provide a cooling fan capable of blocking a back flow with a simple constitution while improving a static pressure characteristic.SOLUTION: A cooling fan (10) generates cooling wind by rotating with a driving force of a motor, and comprises: a boss (11) coupled to the motor; plural blades (12) projecting outward in a radial direction from a position isolated in a peripheral direction of the boss (11); and a coupling ring (13) constituted in an annular form to surround the boss (11) and coupling the plural blades (12). In each of the plural blades (12), a portion (12B) contacting an inner periphery of the coupling ring (13) is an advance blade, and a portion (12C) contacting an outer periphery of the coupling ring (13) is a sweptback blade.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a cooling fan and a fan device that generate cooling air.

Background Art

[0002] In recent years, efforts have been made to promote the Sustainable Development Goals (the 2030 Agenda for Sustainable Development, adopted at the United Nations Summit on September 25, 2015 (Year 27 of Heisei), hereinafter referred to as "SDGs"). Along with this, technologies aiming to reduce waste and defective products are known in order to ensure sustainable production and consumption patterns.

[0003] Conventionally, a cooling fan is installed facing a radiator mounted on an automobile or the like. And it is common to cool the coolant by supplying the cooling air generated by the cooling fan to the radiator.

[0004] As a cooling fan used for such applications, for example, Patent Document 1 discloses a cooling fan including a boss connected to a motor, a plurality of blades protruding radially outward from positions spaced in the circumferential direction of the boss, and a connecting ring configured in an annular shape surrounding the boss and connecting the plurality of blades.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0006] In recent years, the development of electric vehicles (EVs) has been progressing rapidly. EVs generate heat during battery charging, so a cooling fan needs to be operated while the vehicle is stationary. This stationary cooling fan requires low flow rate and high static pressure characteristics. However, as the static pressure characteristics increase, the pressure difference between the front and back of the cooling fan also increases, causing backflow between the cooling fan and the shroud.

[0007] Therefore, as a countermeasure against backflow, a technique for providing a labyrinth structure between the cooling fan and the shroud is disclosed in Patent Documents 2 and 3. However, Patent Documents 2 and 3 have the problem that the structure of the fan device becomes complex.

[0008] Therefore, the object of the present invention is to provide a cooling fan that can prevent backflow with a simple configuration while improving static pressure characteristics. [Means for solving the problem]

[0009] To achieve the above objective, the present invention provides a cooling fan that generates cooling air by rotating with the driving force of a motor, comprising: a boss connected to the motor; a plurality of blades projecting radially outward from positions spaced apart in the circumferential direction of the boss; and a ring-shaped connecting ring surrounding the boss and connecting the plurality of blades, wherein each of the plurality of blades has a forward-swept wing portion that contacts the inner circumferential surface of the connecting ring and a backward-swept wing portion that contacts the outer circumferential surface of the connecting ring. Furthermore, the portion of the blade that contacts the outer circumferential surface of the connecting ring is inclined radially outward toward the front side with respect to the rotation axis of the cooling fan. It is characterized by the following: [Effects of the Invention]

[0010] According to the present invention, a cooling fan capable of preventing backflow with a simple configuration while improving static pressure characteristics can be obtained. Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments. [Brief explanation of the drawing]

[0011] [Figure 1] These are front view (A) and rear view (B) of the fan unit. [Figure 2] This is an exploded perspective view of the fan unit, seen from the front. [Figure 3] The images show the front view (A) and rear view (B) of the cooling fan. [Figure 4] This is a cross-sectional view of IV-IV in Figure 1(A). [Figure 5] This diagram shows the variations in the mounting angles of each part of the blade relative to the connecting ring. [Figure 6] This figure shows variations in the mounting positions of each part of the blade in the width direction of the connecting ring. [Modes for carrying out the invention]

[0012] Hereinafter, as one embodiment of the fan device according to the present invention, a fan device 1 mounted on a vehicle such as an automobile and used to cool the coolant flowing in a radiator (the object to be cooled) will be described.

[0013] (Overall configuration of fan device 1) First, the overall configuration of the fan device 1 will be explained with reference to Figures 1 and 2. Figure 1 is a front view (A) and a rear view (B) of the fan device 1. Figure 2 is an exploded perspective view of the fan device 1 as seen from the front. As shown in Figures 1 and 2, the fan device 1 mainly consists of a fan shroud 2, a motor 3, and a cooling fan 10.

[0014] The fan unit 1 is installed in the engine compartment, for example, so as to face the radiator in the front-to-rear direction. Hereinafter, the front side (radiator side) of the fan unit 1 will be referred to as the "front side," and the rear side (opposite side of the radiator) will be referred to as the "rear side." However, the arrangement of the fan unit 1 and the radiator (cooling target) is not limited to the example described above.

[0015] As an example, the radiator in an engine vehicle mainly exchanges heat between the coolant of the engine and the outside air. In this case, the fan device 1 is mainly driven when the vehicle is running. As another example, the radiator in an EV vehicle exchanges heat between the coolant of the battery and the outside air. In this case, the fan device 1 is mainly driven when the vehicle is stopped while the battery is being charged. And in the present embodiment, the fan device 1 suitable for being driven when the vehicle is stopped will be described.

[0016] The fan shroud 2 is fixed in the engine room by bolts or the like. The fan shroud 2 supports the motor 3 and houses the cooling fan 10 attached to the motor 3. The cooling fan 10 generates cooling air flowing from the front side to the back side of the fan device 1 by rotating when the driving force of the motor 3 is transmitted.

[0017] When the cooling fan 10 rotates, the front side of the fan device 1 (that is, the area where the radiator is installed) becomes negative pressure. As a result, cooling air flowing from the front side to the back side is also generated in the area where the radiator is installed. That is, the front side of the fan device 1 corresponds to the upstream side of the flow of the cooling air generated by the cooling fan 10. On the other hand, the back side of the fan device 1 corresponds to the downstream side of the flow of the cooling air generated by the cooling fan 10.

[0018] (Configuration of the fan shroud 2) The fan shroud 2 is composed of a shroud body 4, a motor support portion 5, and a plurality of stays 6. The fan shroud 2 is integrally formed, for example, by injection molding a resin material. The shroud body 4 has a generally plate-shaped outer shape. A fan housing hole 7 penetrating in the thickness direction is formed in the shroud body 4. The fan housing hole 7 is a circular through hole for housing the cooling fan 10. That is, the diameter of the fan housing hole 7 is slightly larger than the outer dimension of the cooling fan 10 (that is, the diameter of the virtual circle connecting the tips of the plurality of blades 12).

[0019] The motor support portion 5 is positioned inside the fan housing hole 7 (more specifically, in the center of the fan housing hole 7) to support the motor 3. The motor support portion 5 has a generally arc-shaped outer form. Multiple stays 6 extend radially from the motor support portion 5 toward the shroud body 4 at positions spaced apart in the circumferential direction. More specifically, the stays 6 connect the motor support portion 5 to the surface of the shroud body 4 that defines the fan housing hole 7. As a result, the motor support portion 5 is supported by the shroud body 4 in the center of the fan housing hole 7.

[0020] (Motor 3 configuration) Motor 3 generates the driving force to rotate the cooling fan 10. In this embodiment, motor 3 is a brushless motor on the outer rotor side. Furthermore, motor 3 is a so-called "mechatronics-integrated" electric motor in which a driver circuit for controlling the brushless motor is integrated. Motor 3 is attached to the motor support part 5 from the rear side of the fan shroud 2. At this time, the rotor of motor 3 protrudes to the front side of the fan shroud 2 through the motor support part 5. The rotor of motor 3 is then connected to the boss 11 of the cooling fan 10.

[0021] (Cooling fan configuration 10) The cooling fan 10 is connected to the rotor of the motor 3 from the front side of the fan shroud 2. The cooling fan 10 is also housed in the fan housing hole 7 of the fan shroud 2. The cooling fan 10 rotates clockwise in Figure 1(A) around the axis of rotation L (see Figure 4), which extends from the front side to the back side (i.e., in the thickness direction) of the fan device 1, by the driving force transmitted from the motor 3. Hereinafter, the clockwise rotation in Figure 1(A) will be referred to as the "direction of rotation of the cooling fan 10" (sometimes simply referred to as "direction of rotation"). The cooling fan 10 is integrally molded, for example, by injection molding of a resin material. However, the combination of constituent materials and manufacturing methods of the cooling fan 10 is not limited to the example described above.

[0022] Figure 3 shows a front view (A) and a rear view (B) of the cooling fan 10. As shown in Figures 1 to 3, the cooling fan 10 mainly comprises a boss 11, a plurality of (9 in this embodiment) blades 12, and a connecting ring 13.

[0023] The boss 11 is the part that connects to the rotor of the motor 3. The boss 11 generally has the shape of a bottomed cylindrical body. More specifically, as shown in Figure 2, the boss 11 is composed of a disc portion 11a and a cylindrical portion 11b. The disc portion 11a is the part that closes the front end of the cylindrical portion 11b. The disc portion 11a has bolt holes (not shown) through which bolts for fixing the cooling fan 10 to the rotor of the motor 3 are inserted. The cylindrical portion 11b is the part that protrudes from the outer edge of the disc portion 11a toward the motor 3. In addition, multiple blades 12 are attached to the outer circumferential surface of the cylindrical portion 11b.

[0024] Multiple blades 12 are arranged at circumferentially spaced positions on the outer surface of the boss 11 (cylindrical portion 11b). Each of the multiple blades 12 protrudes radially outward. The pitch of the multiple blades 12 (the distance between two adjacent blades 12 in the circumferential direction) may differ for each blade 12. The angle of attack (mounting angle) of the blades 12 is largest at the base end (the connection point with the boss 11) and gradually decreases towards the tip (radially outward). Furthermore, the chord length of the blades 12 is shortest at the base end and gradually increases towards the tip.

[0025] The connecting ring 13 is an annular shape centered on the rotation axis L of the cooling fan 10. Furthermore, the connecting ring 13 is cylindrical in shape, extending in the direction of the rotation axis L of the cooling fan 10. The connecting ring 13 is positioned to surround the boss 11. More specifically, the connecting ring 13 is positioned concentrically with the cylindrical portion 11b of the boss 11.

[0026] Furthermore, the connecting ring 13 is connected to each of the multiple blades 12. In other words, the connecting ring 13 connects the multiple blades 12 to each other. The connecting ring 13 functions as a reinforcing member that suppresses the flapping of the blades 12 caused by the centrifugal force generated when the cooling fan 10 rotates.

[0027] Furthermore, the diameter of the connecting ring 13 is larger than the diameter of the boss 11, and smaller than the diameter of the virtual circle formed by connecting the tips of the multiple blades 12. In other words, the multiple blades 12 protrude radially outward from the connecting ring 13. To put it another way, the connecting ring 13 connects the multiple blades 12 radially inward from the tips of the multiple blades 12.

[0028] In this embodiment, the blade 12 has swept-back and forward-swept wings in portions 12A and 12B inside the connecting ring 13, and a swept-back wing in portion 12C outside the connecting ring 13. More specifically, the blade 12 has a swept-back wing in portion 12A that is close to (contacts with) the boss 11 inside the connecting ring 13, and a forward-swept wing in portion 12B that is close to (contacts with the inner circumferential surface of the connecting ring 13). That is, the blade 12 has swept-back wings in the radially inner and outer portions 12A and 12C, and a forward-swept wing in the radially central portion 12B.

[0029] A forward-swept wing is an airfoil shape that has a lead angle in the direction of rotation, based on a perpendicular line extended from the rotation center of the cooling fan 10 to the center of the chord length of the airfoil cross-section in the radial direction. A swept-back wing is an airfoil shape that has a lag angle in the direction of rotation, based on a perpendicular line extended from the rotation center of the cooling fan 10 to the center of the chord length of the airfoil cross-section in the radial direction. A swept-forward-swept wing is an airfoil shape that transitions from a swept-back wing to a forward-swept wing from the root to the tip of the blade 12.

[0030] However, the shape of the portions 12A and 12B of the blade 12 inside the connecting ring 13 is not limited to the above example, as long as the portion 12B in contact with the inner surface of the connecting ring 13 is a forward-swept wing. As another example, the portions 12A and 12B of the blade 12 inside the connecting ring 13 may be forward-swept wings. That is, the connecting ring 13 connects multiple blades 12 to each other at the boundary between the forward-swept wing portion 12B and the swept-back wing portion 12C.

[0031] Figure 4 is a cross-sectional view of section IV-IV in Figure 1(A). As shown in Figure 4, the forward-swept wing portion 12B generates a cooling airflow parallel to the rotation axis L of the cooling fan 10 (hereinafter referred to as "axial flow F2"). On the other hand, the swept-back wing portions 12A and 12C generate a cooling airflow inclined radially outward with respect to the rotation axis L of the cooling fan 10 (hereinafter referred to as "diagonal flow F1 and F3").

[0032] The axial flow F2 generated by the forward-swept wing section 12B has higher static pressure characteristics at low flow rates (i.e., low rotational speeds) than the mixed flows F1 and F3. Therefore, by making the central section 12B, which plays a dominant role in cooling the object to be cooled, a forward-swept wing, the static pressure characteristics of the cooling fan 10 are improved.

[0033] On the other hand, the diagonal flow F1 generated by the swept-back wing sections 12A and 12C, although having inferior static pressure characteristics compared to axial flow, flows around components located on the rear side of the fan device 1 (e.g., engine, battery), resulting in smoother exhaust of cooling air. Furthermore, by arranging swept-back and forward-swept wings alternately, the timing of when the blades 12 cut through the air in the radial direction can be staggered. As a result, noise associated with the rotation of the cooling fan 10 can be reduced.

[0034] When the cooling fan 10 rotates, the front side of the fan device 1 (left side in Figure 4) becomes negative pressure, and the rear side (right side in Figure 4) becomes positive pressure. As a result, as shown by the dashed arrow in Figure 4, a flow of cooling air (hereinafter referred to as "reverse flow CF") is generated between the fan shroud 2 (more specifically, the surface defining the fan housing hole 7 of the shroud body 4) and the cooling fan 10, moving from the rear side of the fan device 1 to the front side.

[0035] In contrast, the diagonal flow F3 generated by the portion 12C outside the connecting ring 13 flows radially outward at the rear side of the fan device 1, crossing the gap between the fan shroud 2 and the cooling fan 10. As a result, the diagonal flow F3 functions as a fluid seal, preventing the backflow CF from passing between the fan shroud 2 and the cooling fan 10.

[0036] Figure 5 shows variations in the mounting angles θ1 and θ2 of portions 12B and 12C of the blade 12 with respect to the connecting ring 13. In Figure 5, the dashed line represents portion 12B that is in contact with the inner surface of the connecting ring 13, and the solid line represents portion 12C that is in contact with the outer surface of the connecting ring 13. The mounting angles θ1 and θ2 are the angles made by the chords of portions 12B and 12C with respect to the rotation axis L of the cooling fan 10.

[0037] As an example, as shown in Figure 5(A), the mounting angle θ2 of the portion 12C that contacts the outer circumferential surface of the connecting ring 13 may be smaller than the mounting angle θ1 of the portion 12B that contacts the inner circumferential surface of the connecting ring 13. This increases the flow rate of the mixed flow F3, thereby improving the performance of the fluid seal. On the other hand, as another example, as shown in Figure 5(B), the mounting angle θ2 of the portion 12C that contacts the outer circumferential surface of the connecting ring 13 may be larger than the mounting angle θ1 of the portion 12B that contacts the inner circumferential surface of the connecting ring 13. This reduces the flow rate of the mixed flow F3, thus preventing noise, especially at low rotational speeds. Thus, the combination of mounting angles θ1 and θ2 should be selected according to the performance and application required for the fan device 1.

[0038] Figure 6 shows variations in the mounting positions of portions 12B and 12C of the blade 12 in the width direction of the connecting ring 13 (the direction of the rotation axis L of the cooling fan 10). In Figure 6, the dashed line indicates portion 12B that is in contact with the inner circumferential surface of the connecting ring 13, and the solid line indicates portion 12C that is in contact with the outer circumferential surface of the connecting ring 13. Furthermore, in this specification, even if portions 12B and 12C sandwiching the connecting ring 13 are discontinuous, as shown in Figure 6, they will be treated as a single blade 12.

[0039] As an example, as shown in Figure 6(A), the portion 12C that contacts the outer circumferential surface of the connecting ring 13 may be positioned upstream of the cooling airflow portion 12B that contacts the inner circumferential surface of the connecting ring 13. This causes the diagonal flow F3 in Figure 4 to move parallel to the front side of the fan device 1. As another example, as shown in Figure 6(B), the portion 12C that contacts the outer circumferential surface of the connecting ring 13 may be positioned downstream of the cooling airflow portion 12B that contacts the inner circumferential surface of the connecting ring 13. This causes the diagonal flow F3 in Figure 4 to move parallel to the rear side of the fan device 1. In this way, the combination of the arrangements of portions 12B and 12C should be selected according to the thickness of the fan shroud 2 so that the diagonal flow F3 is directed toward the rear corner E of the surface defining the fan housing hole 7 of the shroud body 4.

[0040] According to the above embodiment, for example, the following effects are achieved.

[0041] According to the above embodiment, the static pressure characteristics of the cooling fan 10 are improved by making the central portion 12B, which plays a dominant role in cooling the object to be cooled, a forward-swept wing. Furthermore, by making the portion 12C outside the connecting ring 13 a backward-swept wing, the diagonal flow F3 can function as a fluid seal. In addition, since there is no need to modify the structure of the fan shroud 2, the structure of the fan device 1 can be kept from becoming complicated.

[0042] This makes it possible to obtain a cooling fan 10 that can prevent backflow CF with a simple configuration while improving static pressure characteristics. In other words, according to the above embodiment, static pressure characteristics equivalent to those of a conventional fan device can be achieved with a small fan device 1. Furthermore, compared to Patent Documents 2 and 3, the structure of the fan shroud 2 is simpler, which simplifies the manufacturing process and contributes to a reduction in raw materials (amount of resin).

[0043] Furthermore, according to the above embodiment, by making the base end portion 12A of the blade 12 a swept-back wing, the blade 12 has swept-back and forward-swept wings arranged alternately in the radial direction. As a result, the timing of when the blade 12 cuts through the air can be staggered in the radial direction, thereby reducing the noise associated with the rotation of the cooling fan 10.

[0044] Furthermore, according to the above embodiment, by making the mounting angles θ1 and θ2 different, appropriate fluid sealing performance can be achieved in accordance with the fan shroud 2. This makes it possible to obtain a cooling fan 10 with a shape that suits the performance and application required for the fan device 1.

[0045] Furthermore, according to the above embodiment, by shifting the mounting positions of portions 12B and 12C in the width direction of the connecting ring 13, the diagonal flow F3 can be adjusted to be directed towards the corner E. This makes it possible to obtain a cooling fan 10 that exhibits appropriate fluid sealing performance according to the different thicknesses of the fan shroud 2 required by the mounting side.

[0046] In the above embodiment, an example was described in which the fan device 1 is mounted on a vehicle driven by an electric motor, but the vehicle on which the fan device 1 is mounted may also be driven by an engine. Also, in the above embodiment, an example of a radiator was described as the object to be cooled by the fan device 1, but the object to be cooled by the fan device 1 is not limited to this.

[0047] Embodiments of the present invention have been described above. It should be noted that the present invention is not limited to the embodiments described above, and various modifications are included. For example, the embodiments described above are described in detail to make the present invention easier to understand, and are not necessarily limited to those having all the described configurations. Furthermore, it is possible to replace some of the configurations of this embodiment with those of other embodiments, and it is also possible to add configurations from other embodiments to the configuration of this embodiment. Moreover, it is possible to add, delete, or replace some of the configurations of this embodiment with those of other embodiments. [Explanation of Symbols]

[0048] 1. Fan device 2 Fan Shroud 3 motors 4 Shroud body 5. Motor support section 6 Stay 7 Fan housing holes 10 Cooling Fans 11 Bosses 11a Disc section 11b Cylindrical section 12 blades 12A, 12B, 12C: Part 13 Connecting rings

Claims

1. In a cooling fan that generates cooling air by rotating due to the driving force of a motor, A boss connected to the motor, Multiple blades protruding radially outward from positions spaced apart in the circumferential direction of the boss, It comprises a ring-shaped connecting ring that surrounds the boss and connects a plurality of the blades, Each of the multiple blades is The portion that contacts the inner circumferential surface of the connecting ring is a forward-swept wing. The portion that contacts the outer surface of the connecting ring is a swept-back wing. A cooling fan characterized in that the portion of the blade that contacts the outer circumferential surface of the connecting ring is inclined radially outward toward the front side with respect to the rotation axis of the cooling fan.

2. In the cooling fan described in claim 1, A cooling fan characterized in that the portion of the multiple blades from the boss to the inner circumferential surface of the connecting ring is a retracted and forward-swept wing.

3. In the cooling fan described in claim 1, A cooling fan characterized in that the mounting angle of the portion in contact with the outer circumferential surface of the connecting ring is different from the mounting angle of the portion in contact with the inner circumferential surface of the connecting ring.

4. In the cooling fan described in claim 1, A cooling fan characterized in that the portion that contacts the outer circumferential surface of the connecting ring is offset from the portion that contacts the inner circumferential surface of the connecting ring in the width direction of the connecting ring.

5. Fan shroud and, A motor that generates driving force is supported by the aforementioned fan shroud, A fan device characterized by comprising a cooling fan according to claim 1, wherein the boss is connected to the motor and rotates.

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