Axial flow fan

Abstract

[Problem] To provide an axial flow fan capable of increasing the air volume between fan blades and improving horsepower efficiency by improving the shape of fan blades in a structure in which the flow of air and wind is not vertically received air between the fan blades. [Solution] Provided is an axial flow fan including a plurality of fan blades radially extending on the outer periphery of a hub. The axial flow fan is characterized by being configured such that: a taper boss part of a root section of a blade body on a side opposing the back surface of an adjacent fan blade is formed as a wide surface inclined in the direction of rotation of the fan; and a portion curved to a windward side is provided at a tip part on the leeward side of the fan blade.

Description

Technical Field

[0001] This invention generally relates to an axial-flow engine cooling fan that is rotationally driven for cooling an automobile engine or the like, and more particularly to an axial-flow fan having a plurality of fan blades radially extending from the outer periphery of a hub.

Background Art

[0002] As a conventional axial-flow fan of this type, for example, as shown in FIG. 6, there is known a structure constituted by a plurality of fan blades 12 radially extending from the outer periphery of a hub 11 (see Patent Document 1). As shown in an enlarged view in FIG. 4, the fan blade 12 of this type of axial-flow fan has a structure in which a blade side edge portion 12a formed of a vertical wall surface is integrally connected to a portion of a tapered boss portion 12b formed in a substantially L-shape (sickle shape) at the base of the blade body, and is radially integrally projected through a blade fixing portion 12c fixed to the hub 11 at a right angle to the axis. Further, as shown in FIGS. 4 and 5, the conventional axial-flow fan has an angle degree substantially of 90 degrees between the blade side edge portion 12a and the arc-shaped portion of the blade 12. In the figure, 12d is the blade leading edge, 12e is the blade trailing edge, 13 is a mounting member to the mating member, and 13a is a fastening bolt hole.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, the conventional axial flow fans shown in Figures 4 and 5 have the following problems. Specifically, in the case of the axial flow fans shown in Figures 4 and 5, the tapered boss portion 12b and the blade leading edge 12d overlap when forming the fan blades, making it difficult to form the blades using normal injection molding. For this reason, in the case of the conventional axial flow fans, it was necessary to form a blade side edge portion 12a consisting of a vertical wall surface between the tapered boss portion 12b and the blade leading edge 12d to prevent overlap. However, in the case of a blade side edge portion 12a consisting of a vertical wall surface, the vertical wall surface provides significant resistance to the airflow passing through that portion, leading to a reduction in airflow between the fan blades and resulting in a disadvantage of low horsepower efficiency. Furthermore, as shown in Figures 4 and 5, the angle θ between the blade side edge portion 12a and the blade leading edge portion 12d of this axial flow fan is approximately 2 degrees, which causes a reduction in airflow between the fan blades and inevitably leads to a decrease in horsepower efficiency. Note that angle θ is the angle required for a typical draft taper in resin molding.

[0005] This invention was made to overcome the shortcomings of the conventional axial flow fans described above. By improving the shape of the fan blades so that they do not receive air or wind flow perpendicularly between the fan blades, the invention aims to provide an axial flow fan that can increase the airflow between the fan blades and improve horsepower efficiency. [Means for solving the problem]

[0006] The axial flow fan according to the present invention is an axial flow fan having a plurality of fan blades extending radially from the outer circumference of a hub, characterized in that the tapered boss portion at the base of the blade body on the side facing the back of an adjacent fan blade has a wide surface inclined in the direction of fan rotation, and the downwind tip of the fan blade has a portion that curves toward the upwind side.

[0007] Furthermore, while the taper angle θ of the leading edge at the base of the fan blades of this axial flow fan is typically around 2 degrees in conventional designs, the present invention is characterized by a taper angle θ of 2 degrees or more and less than 90 degrees. [Effects of the Invention]

[0008] The axial flow fan according to the present invention has a wide, flat surface shape at the base of the blade body, with the tapered boss inclined in the direction of fan rotation. This significantly reduces the vertical reception of wind and airflow between the fan blades, thereby increasing airflow and reducing the horsepower increase required by the increased airflow. Furthermore, by providing a curved portion on the windward side at the downwind tip of the fan blade, the airflow between the fan blades is increased, improving horsepower efficiency. In addition, by setting the taper angle θ of the leading edge at the base of the fan blade to 2 degrees or more and less than 90 degrees, the vertical reception of air and windflow between the fan blades is almost eliminated, further increasing the airflow between the fan blades and improving horsepower efficiency even more effectively. [Brief explanation of the drawing]

[0009] [Figure 1] This is an enlarged perspective view of a key part showing one embodiment of an axial flow fan according to the present invention. [Figure 2] Figure 1 is a perspective view showing the fan blades of an axial fan as seen from the inside. [Figure 3] Figure 1 is an explanatory diagram showing the leading edge taper angle at the base of the fan blades of the axial flow fan. [Figure 4] This is an enlarged perspective view of a key part showing an example of a conventional axial fan that is the subject of the present invention. [Figure 5] Figure 4 is an explanatory diagram showing the leading edge taper angle at the base of the fan blades of a conventional axial fan. [Figure 6] Figure 4 is a front view showing a portion of a conventional axial flow fan. [Modes for carrying out the invention]

[0010] Hereinafter, an embodiment of the axial flow fan according to the present invention will be described with reference to the attached drawings. The axial fan shown in Figure 1 has a ring-shaped hub 11 similar to the conventional axial fan shown in Figure 4, with multiple fan blades 1 extending radially from the hub. Its features include, as shown in Figures 1 and 2, a tapered boss portion 1a formed at the base of the fan blade 1 body on the side facing the back of an adjacent fan blade 1, which is a wide, flat surface inclined in the direction of fan rotation, and a structure in which the tapered boss portion 1a and the fan blade 1 body are connected by a substantially triangular blade base portion 1b and a blade arc-shaped surface 1f. Furthermore, a curved portion 1c is formed at the downwind tip of the fan blade 1, which bends towards the upwind side. In addition, as shown in Figure 3, the inclination angle θ of the substantially triangular blade base portion 1b, that is, the taper angle θ of the leading edge of the base of the fan blade 1, is set to 2 degrees or more and less than 90 degrees. The reason for setting the taper angle θ of the leading edge at the base of the fan blade 1 to 2 degrees or more and less than 90 degrees is to reduce the vertical impact of airflow between the fan blades and to more effectively increase the airflow between the fan blades, thereby enabling further improvement in horsepower efficiency.

[0011] Furthermore, the fan blade 1 of the present invention has an integral structure with a blade fixing portion 1d formed at the base of the blade body, and has a structure that combines a wide, flat tapered boss portion 1a that is obliquely inclined in the direction of fan rotation, a blade base portion 1b where the joint surface between the tapered boss portion 1a and the blade fixing portion 1d is a substantially triangular slope, and a blade arc-shaped surface 1f formed between the tapered boss portion 1a and the inner wall surface 1e of the blade, and also has a curved portion 1c that bends towards the windward side at the leeward tip of the fan blade 1. In the figure, 1g is the leading edge of the blade and 1h is the trailing edge of the blade.

[0012] The axial flow fan with such a structure has the fan blade 1, the tapered boss portion 1a, the blade attachment root portion 1b, the blade arc-shaped surface 1f, etc. integrally provided by injection molding with a resin material or casting molding with an aluminum or aluminum alloy material.

[0013] In the axial flow fan of the embodiment shown in FIGS. 1 to 3 above, the tapered boss portion 1a at the attachment root of the fan blade 1 main body on the side facing the back of the adjacent fan blade 1 has a shape of a wide flat surface inclined in the fan rotation direction. Therefore, the vertical reception of the flow of wind or air between the fan blades 1 is significantly reduced, resulting in an increase in the air volume and a reduction in the increase in horsepower due to the increase in the air volume. Further, due to the action of the curved portion 1c that bends upward provided at the tip of the fan blade 1 on the leeward side and the taper angle θ (more than 2 degrees and less than 90 degrees) of the leading edge of the blade attachment root of the fan blade, an increase in the air volume between the fan blades can be achieved, and it becomes possible to improve the horsepower efficiency.

[0014] According to the experiments of the present inventors, for example, when comparing the air volumes when the axial flow fan of the present invention and a conventional axial flow fan are rotated at the same output (same horsepower) and air is blown with the same vehicle resistance, When using the axial fan of the present invention The result was that the air volume improved by about 3 to 4% or more.

Explanation of Reference Numerals

[0015] 1, 12 Fan blade 1a Tapered boss portion 1b Blade attachment root portion 1c Curved portion 1d Blade fixing portion 1e Blade inner wall surface 1f Blade arc-shaped surface 1g Blade leading edge 1h Blade trailing edge 11 Hub 12a Blade side edge portion 12b Tapered boss portion 12c Blade fixing portion 12d Blade leading edge 12e Blade trailing edge 13. Mounting component (insert) 13a Fastening bolt holes θ Taper angle

Claims

1. An axial flow fan having multiple fan blades extending radially around the outer circumference of a hub, characterized in that the tapered boss portion at the base of the blade body facing the back of an adjacent fan blade is shaped as a wide surface inclined in the direction of fan rotation, and the downwind tip of the fan blade has a portion that curves toward the upwind side.

2. The axial flow fan according to claim 1, characterized in that the taper angle θ of the leading edge of the base of the fan blade is 2 degrees or more and less than 90 degrees.

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