Axial flow fan and fan stator

Abstract

In a resin-made axial flow fan composed of an outer ring, a hub arranged at the center of the outer ring, and a plurality of blades independently provided between the outer ring and the hub, provided are an axial flow fan and a fan stator capable of suppressing a rapid flow change by optimizing a fan shape and the number of blades, and obtaining high efficiency and rectification effect.　The resin-made axial flow fan, which is provided with an outer ring, a hub arranged at the center of the outer ring, and a plurality of blades between the outer ring and the hub, is characterized in that the blade is structured to retreat from the root to the middle of the hub, sweep forward from the middle to the outer ring, form a wide shape with an actual length, and be twisted at a desired angle.

Description

Axial fans and fan stators

[0001] This invention relates to an axial flow engine cooling fan (including applications for cooling EV batteries, motors, FCV stacks, and accessories; hereinafter simply referred to as "engine cooling fan") that is generally driven to rotate for cooling automobile engines and the like, and to a fan stator for fixing the engine cooling fan via an electric motor that drives the fan.

[0002] Axial-flow engine cooling fans that are rotationally driven are commonly used in vehicles such as automobiles for cooling purposes. Because the shape of this type of cooling fan must meet requirements such as low noise, high efficiency, compactness, and the ability to achieve good pressure and flow rates, various fan shapes have been proposed to meet these requirements. For example, an axial-flow fan is known that has fan blades extending radially from the outer periphery of a cylindrical hub with a generally T-shaped cross section, with the curved surface located on the leading edge of the fan blade extending from the shaft end face toward the base of the fan blade (see Patent Document 1). However, recent demand for electric vehicles (EVs) has led to a demand for cooling fans that are driven by an electric motor rather than the rotational power of the engine.

[0003] However, when driving a fan using an electric motor or other rotary drive means, a fan and a stator are required, and the shape or structure of each of the fan and stator affects performance. Therefore, a known fan stator for fixing via an electric motor that drives an engine cooling fan has a structure in which, for example, axially flat plate-shaped stays are arranged radially between a central mount and an annular outlet bell (see Patent Document 2).

[0004] Japanese Patent No. 4994975 Japanese Patent Application Laid-Open No. 2012-229693

[0005] However, the above-described conventional axial-flow engine cooling fans and stators have the following problems. For example, in the case of a 500-W engine cooling fan, the short length of the fan blades shortens the distance over which the airflow generated by the fan must be deflected, resulting in pressure resistance on the fan blade surfaces and reduced efficiency. In addition, in the case of a stator dedicated to a 500-W engine cooling fan, the stays themselves have the same cross-sectional shape as the fan blades, but the fan outlet flow does not match the shape of the stator vanes, resulting in the drawback of obstructing the airflow generated by the fan and increasing drive torque. In addition, in the case of a 1-kW engine cooling fan, the number of blades typically is 11, which not only causes the airflow generated by the front and rear blades to interfere with the airflow around the blades, but also shortens the distance over which the airflow must be deflected due to the short blade length, resulting in pressure resistance on the blade surfaces and reduced efficiency. In addition, in the case of a 1-kW engine cooling fan, the stays have a flat axial plate shape, resulting in the drawback of obstructing the airflow generated by the fan and increasing drive torque.

[0006] The present invention has been made to overcome the drawbacks of conventional axial fans and fan stators described above, and aims to provide an axial fan and fan stator that, in a plastic axial fan configured with an outer ring, a hub located at the center of the outer ring, and a number of blades independently arranged between the outer ring and the hub, has the advantage of suppressing sudden changes in flow by optimizing the fan shape and number of blades, thereby achieving high efficiency and a rectifying effect.

[0007] The axial flow fan (motor-driven fan) of the present invention is a resin fan configured with a circular outer ring, a hub consisting of a circular central support placed at the center of the outer ring, and a plurality of blades independently arranged between the outer ring and the hub, with the blades receding from their bases where they meet the hub consisting of the central support to their middle, and the blades being forward-swept from the middle to the outer ring, making them wide blades with a long actual length, and the blades having a structure in which they are twisted at a desired angle.

[0008] This axial flow fan is characterized in that a circular outer ring, a hub consisting of a circular central support, and a plurality of blades are integrally molded.

[0009] Furthermore, the fan stator for fixing an axial flow fan (a motor-driven fan) according to the present invention is characterized in that the stays arranged radially between the central mount and the annular outlet bell have a blade cross-sectional shape that matches the fan outlet vector (wind direction and air volume from the fan to the stays), and each stay is twisted at a desired angle in the direction of fan rotation.

[0010] The axial flow fan of the present invention is a resin fan comprising a circular outer ring, a hub consisting of a circular central support positioned at the center of the outer ring, and a plurality of independent blades disposed between the outer ring and the hub. The blades are swept back from their bases at the central support to their midpoints, and are forward-swept from their midpoints to the outer ring, resulting in long blade lengths. The blades are twisted at a desired angle. For example, in a 500W engine cooling fan, the fan suppresses sudden changes in flow, improving efficiency and providing a streamlining effect. In a 1kW engine cooling fan, the fan suppresses sudden changes in flow, improving efficiency, similar to a 500W cooling fan. Furthermore, the reduced number of blades reduces flow interference between the front and rear blades, improving efficiency. Furthermore, the fan stator stays have a blade cross-sectional shape aligned with the fan outlet vector, and each stay is twisted at a desired angle in the direction of fan rotation, improving fan performance.

[0011] FIG. 1 is a perspective view showing an embodiment of an axial flow fan (for 1 kW output only) according to the present invention. FIG. 2 is a perspective view showing an embodiment of a fan stator dedicated to the axial flow fan shown in FIG. 1. FIG. 3 is a perspective view showing an embodiment of another axial flow fan (for 500 W output only) according to the present invention. FIG. 4 is a perspective view showing an embodiment of a fan stator for the axial flow fan shown in FIG. 3. FIG. 5 is a diagram showing a comparative example of the specific shape (including dimensions) of a conventional axial flow fan (for 1 kW output only). FIG. 6 is a diagram showing an embodiment of the specific shape (including dimensions) of an axial flow fan (for 1 kW output only) according to the present invention. FIG. 7 is a diagram showing a comparative example of the specific shape (including dimensions) of a conventional stator (for 1 kW output only). FIG. 8 is a diagram showing an embodiment of the specific shape (including dimensions) of a stator (for 1 kW output only) according to the present invention. FIG. 9 is a diagram comparing (P-Q performance) ring fans of a conventional 1 kW model and a 1 kW model according to the present invention at 3050 rpm (vertical axis: static pressure, horizontal axis: air volume). 1 is a diagram comparing (L-Q performance) a conventional 1kW ring fan and a 1kW ring fan of the present invention at 3050 rpm (vertical axis: horsepower, horizontal axis: air volume). 2 is a diagram comparing (EQ performance) a conventional 1kW ring fan and a 1kW ring fan of the present invention at 3050 rpm (vertical axis: static pressure efficiency, horizontal axis: air volume). 3 is a diagram showing a comparative example of the specific shape (including dimensions) of a conventional axial flow fan (dedicated to 500W output). 4 is a diagram showing an example of the specific shape (including dimensions) of an axial flow fan (dedicated to 500W output) of the present invention. 5 is a diagram showing a comparative example of the specific shape (including dimensions) of a conventional stator (dedicated to 500W output). 6 is a diagram showing an example of the specific shape (including dimensions) of a stator (dedicated to 500W output) of the present invention. 7 is a diagram comparing (P-Q performance) a conventional 500W ring fan and a 500W ring fan of the present invention at 4100 rpm (vertical axis: static pressure, horizontal axis: air volume). 1 is a diagram comparing (L-Q performance) a conventional 500W ring fan and a 500W ring fan of the present invention at 4100 rpm (vertical axis: horsepower, horizontal axis: air volume). 2 is a diagram comparing (EQ performance) a conventional 500W ring fan and a 500W ring fan of the present invention at 4100 rpm (vertical axis: static pressure efficiency, horizontal axis: air volume).

[0012] An embodiment of an axial flow fan according to the present invention will now be described with reference to the accompanying drawings. The axial flow fan 1 shown in Fig. 1 (dedicated for a 1 kW output) is comprised of a circular outer ring 11, a hub 12 consisting of a circular central support positioned at the center of the outer ring, and a plurality of blades 13 disposed between the outer ring 11 and the hub 12. The axial flow fan is characterized by the shape of the plurality of blades 13 (nine blades) disposed between the outer ring 11 and the hub 12. Specifically, the 1 kW axial flow fan according to the present invention has blades 13 that are swept back from their bases at the hub 12, which is the central support, to their middles, and have forward-swept blades from their middles to the outer ring 11, resulting in blades 13 that are approximately 1.3 to 1.5 times longer and wider than conventional blades. Furthermore, the bases of both ends of each blade 13 are twisted at a desired inclination angle, integrally joining the inner surface of the outer ring 11 and the outer surface of the hub 12. The width, length, and inclination angle of the base of both ends of the fan blades 13 are not particularly limited, and are set appropriately according to the output of the axial fan so as to suppress sudden changes in the flow of air or wind between the fan blades 13 and achieve high efficiency.

[0013] 2, an example of a stator 2 for an axial fan with an output of 1 kW is made up of a circular outer ring 21, a central hub holder 22, stays 23 arranged radially between the outer ring 21 and the hub holder 22, and a reinforcing ring 24. It is characterized in that the blade-shaped stays 23 arranged radially between the outer ring 21 and the hub holder 22 have both ends twisted at a desired inclination angle, so that they are integrally joined to the inner surface of the outer ring 21 and the outer surface of the hub holder 22. The reason why the stays 23 are blade-shaped is to improve fan performance.

[0014] In the structure using the axial fan 1 shown in FIG. 1 and the axial fan stator 2 shown in FIG. 2, the blades 13 are set back from their base at the hub 12, which is the central support, to the middle, and are forward-swept from the middle to the outer ring 11, making the actual length approximately 1.3 to 1.5 times longer than conventional blades. This not only ensures the desired air volume, but also ensures that the bases at both ends of each blade 13 are twisted at the desired inclination angle and are integrally joined to the inner surface of the outer ring 11 and the outer surface of the hub 12. Furthermore, with the added effect of reducing the number of blades, interference between the flows of the front and rear blades is suppressed, resulting in higher efficiency.

[0015] More specifically, the shapes and dimensions (Tables 1 and 2) of an axial fan dedicated to an output of 1 kW according to the present invention (FIG. 6) and an axial fan stator according to the present invention (FIG. 8) and a conventional axial fan dedicated to an output of 1 kW (FIG. 5) and a conventional axial fan stator (FIG. 7) are shown, along with experimental data (performance comparison) (FIGS. 9 to 11). As can be seen from the experimental data, the axial fan and stator for an axial fan dedicated to an output of 1 kW according to the present invention have a +7.2% increase in air volume, a +15.0% increase in static pressure, a -2.4% horsepower saving, and a +10.8% increase in static pressure efficiency, compared to the conventional axial fan and stator for an axial fan.

[0016] The axial fan 3 for a 500 W output shown in Fig. 3 and the axial fan stator 4 for a 500 W output shown in Fig. 4 are basically similar in structure to the axial fan 1 for a 1 kW output shown in Figs. 1 and 2 and the stator 2 for a 1 kW output shown in Fig. 2, and provide similar functions and effects. The axial fan 3 for a 500 W output shown in Fig. 3 is composed of a circular outer ring 31, a hub 32 made of a circular central support positioned at the center of the outer ring, and a plurality of fan blades 33 disposed between the outer ring 31 and the hub 32. The only differences from the axial fan 1 for a 1 kW output shown in Fig. 1 are that the number of blades 33 disposed between the outer ring 31 and the hub 32 is fewer, and the shape and twist angle of the fan blades 33 are slightly different. The width, length, and inclination angles of the base ends of the fan blades 33 are not particularly limited, and needless to say, they are appropriately set according to the output of the axial fan so as to suppress sudden changes in the flow of air or wind between the fan blades 33 and thereby achieve high efficiency. Furthermore, the width, length, and inclination angle of the base of both ends of the fan blades 33 are not particularly limited, as with the axial fan 1 dedicated to an output of 1 kW, and are set appropriately according to the output of the axial fan so as to suppress sudden changes in the flow of air or wind between the fan blades 33 and achieve high efficiency.

[0017] As mentioned above, the stator 4 for an axial fan with a 500 W output shown in Fig. 4 has substantially the same structure as the stator 2 for an axial fan with a 1 kW output shown in Fig. 2. That is, it is composed of a circular outer ring 41, a central hub holder 42, and stays 43 arranged radially between the outer ring 41 and the hub holder 42. It is characterized in that, like the stator 2 for an axial fan with a 1 kW output, the blade-shaped stays 43 arranged radially between the outer ring 41 and the hub holder 42 are twisted at a desired inclination angle at both ends so that they are integrally joined to the inner surface of the outer ring 41 and the outer surface of the hub holder 42. The reason why the stays 43 are blade-shaped is to improve fan performance, as with the axial fan with a 1 kW output.

[0018] More specifically, the shapes and dimensions (Tables 3 and 4) of the axial fan (FIG. 13) and stator (FIG. 15) for a 500W output according to the present invention and a conventional axial fan (FIG. 12) and stator (FIG. 14) for a 500W output are shown, along with experimental data (performance comparison) (FIGS. 16 to 18). As can be seen from the experimental data, compared to the conventional axial fan and stator for a 500W output, the axial fan and stator for a 500W output according to the present invention have a horsepower increase of +4.7%, but have improved air volume by +6.5%, static pressure by +13.3%, and static pressure efficiency by +6.9%.

[0019]

[0020]

[0021]

[0022]

[0023]

[0024]

[0025] 1 Axial flow fan dedicated to 1 kW output 2 Stator for axial flow fan dedicated to 1 kW output 3 Axial flow fan dedicated to 500 W output 4 Stator for axial flow fan dedicated to 500 W output 11, 21, 31, 41 Outer ring 12, 32 Hub 13, 33 Fan blade 22, 42 Hub support 23, 43 Stay 24 Reinforcement ring

Claims

1. A plastic fan consisting of a circular outer ring, a hub consisting of a circular central support placed at the center of the outer ring, and a number of blades independently arranged between the outer ring and the hub, wherein the blades are recessed from their base at the central support to the middle, and the blades from the middle to the outer ring are forward-swept blades, making them wide blades with a long actual length, and the blades are twisted at a desired angle.

2. An axial flow fan as claimed in claim 1, characterized in that a hub consisting of a circular outer ring and a circular central support is integrally formed with a plurality of blades.

3. A fan stator for fixing an axial flow fan, characterized in that the stays arranged radially between the central mount and the annular outlet bell have a blade cross-sectional shape that matches the fan outlet vector, and each stay is twisted at a desired angle in the direction of fan rotation.

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