Axial flow fan
The axial flow fan design with a convex curve at the blade edge minimizes air leakage and maintains high performance by optimizing airflow direction, addressing the issues of air leakage and efficiency in conventional fans.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- SANYO DENKI CO LTD
- Filing Date
- 2022-09-30
- Publication Date
- 2026-06-03
AI Technical Summary
Existing axial flow fans face performance degradation due to air leakage at the outer peripheral edge of the blades, especially at high rotational speeds or static pressures, and increasing the warping angle to prevent leakage leads to reduced air volume.
The axial flow fan design incorporates a curved portion at the outer edge of the blades that rises toward the suction side, with a convex curve starting position set such that the length from the leading edge to the vertex is 0 < Y ≦ 0.6X, minimizing air leakage while maintaining efficient airflow.
The design enhances fan performance by maintaining high air volume and static pressure, achieving superior efficiency compared to conventional designs.
Smart Images
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Abstract
Description
Technical Field
[0001] The present invention relates to an axial flow fan.
Background Art
[0002] Patent Document 1 discloses an axial flow fan provided with a convex edge along the outer edge of the blade.
Prior Art Document
Patent Document
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] According to the axial flow fan of Patent Document 1, by providing a warping portion along the outer peripheral edge of the blade, when the impeller rotates, air is prevented from flowing out to the outside of the outer peripheral edge by centrifugal force, and air flows along the outer peripheral edge, improving fan performance such as air volume-static pressure characteristics.
[0005] However, when the rotational speed or static pressure of the impeller increases, there is a risk that air will flow out to the outside of the outer peripheral edge beyond the warping portion, resulting in a decrease in fan performance. In addition, in order to prevent air from flowing out to the outside of the outer peripheral edge beyond the warping portion, it is conceivable to increase the warping angle of the warping portion. However, when the warping angle of the warping portion is increased, although the outflow of air to the outside of the outer peripheral edge is suppressed, the air volume decreases, and there is a risk that the fan performance will decrease instead.
[0006] Therefore, an object of the present invention is to provide an axial flow fan with high fan performance.
Means for Solving the Problems
[0007] The axial flow fan according to one aspect of the present invention is An axial flow fan having multiple blades that generates an airflow from the intake side to the discharge side, The aforementioned feathers are, The outer edge of the aforementioned blade is provided with a curved portion that rises toward the suction side, When viewed from the suction side, the starting position of the curved portion provided along the outer edge is a convex curve that protrudes radially outward. When viewed from the intake side, if the total length of the convex curve is X, then the length Y from the leading edge of the blade to the vertex of the convex curve is 0 <Y≦0.6Xである。 [Effects of the Invention]
[0008] According to the present invention, it is possible to provide an axial flow fan with high fan performance. [Brief explanation of the drawing]
[0009] [Figure 1] This is a perspective view of an axial flow fan according to an embodiment of the present invention. [Figure 2] This is a perspective view of the impeller of an axial fan according to an embodiment of the present invention. [Figure 3] This is a plan view showing a portion of a conventional impeller. [Figure 4] This is a plan view showing a part of the impeller relating to Comparative Example 1. [Figure 5] This is a cross-sectional view of a portion of the impeller shown in Figure 4. [Figure 6] This is a plan view showing a part of the impeller relating to Comparative Example 2. [Figure 7] This is a plan view showing a part of the impeller relating to Comparative Example 3. [Figure 8] This is a plan view showing a part of an impeller according to an embodiment of the present invention. [Figure 9] This graph shows the measurement results of static pressure and power consumption relative to airflow. [Figure 10] This graph shows the measured power consumption as a function of the position of the apex of the convex curve, which is the starting position of the warped section, for multiple impellers having similar PQ characteristics. [Figure 11] It is a graph showing the measurement results of the power consumption in free air with respect to the position of the apex of the convex curve which is the starting position of the warpage portion.
Embodiments for Carrying out the Invention
[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the description of the embodiments, for members having the same reference numerals as those already described, the description thereof will be omitted for the sake of convenience. Also, the dimensions of each member shown in these drawings may be different from the actual dimensions of each member for the sake of convenience.
[0011] FIG. 1 is a perspective view showing an example of an axial flow fan 1 according to an embodiment of the present invention. (A) in FIG. 1 is a perspective view seen from the suction side (hereinafter also referred to as the upstream side) of the axial flow fan 1, and (B) is a perspective view seen from the discharge side (hereinafter also referred to as the downstream side) of the axial flow fan 1. As shown in FIG. 1, the axial flow fan 1 includes an impeller 3 having a plurality of blades 2, a motor 4 provided inside the impeller 3, a housing 5 that houses the impeller 3 and the motor 4, and spokes 6 that connect the impeller 3 and the housing 5.
[0012] The motor 4 rotationally drives the impeller 3 in the rotational direction V about the rotation axis line Ax of the rotation shaft 8.
[0013] The housing 5 is formed, for example, in a substantially rectangular shape as a whole. The housing 5 has a suction port 5a for sucking air and a discharge port 5b for discharging the sucked air. By the rotation of the plurality of blades 2, the air sucked from the suction port 5a is sent in the blowing direction W and discharged to the outside from the discharge port 5b. In other words, the axial flow fan 1 generates an air flow flowing from the suction port 5a to the discharge port 5b. The housing 5 has an inner peripheral wall 51 that forms a cylindrical space for housing the impeller 3. The inner diameter of the inner peripheral wall 51 is slightly larger than the outer diameter of the impeller 3.
[0014] FIG. 2 is a perspective view of the impeller 3 of the axial flow fan 1 according to an embodiment of the present invention. In an example shown in the figure, the impeller 3 has a cup-shaped hub 9 and a plurality of blades 2 extending radially outward from the hub 9. The plurality of blades 2 are attached to the peripheral wall portion of the hub 9. The plurality of blades 2 are forward blades in which the front end of the outer peripheral edge 2a of the blade 2 advances in the rotational direction V more than the front end of the base 2b of the blade 2. Further, the plurality of blades 2 are each provided inclined with respect to the axial direction of the rotation axis 8. In the following description, when referring to the front-back direction, it shall be defined with respect to the rotational direction V. That is, the upstream side in the rotational direction is called the front, and the downstream side in the rotational direction is called the rear. Among the outer edges of the blade 2, the edge located in the front may be called the leading edge 2c, the edge located radially outside may be called the outer peripheral edge 2a, and the edge located in the rear may be called the trailing edge 2d (see FIG. 3).
[0015] FIG. 3 is a plan view seen from the upstream side showing a part of the impeller 3 according to the conventional example. In FIG. 3, only one of the plurality of blades 2 is shown for easy understanding. Also, in order to explain the air flow on the surface of the blade 2, the air flows W1 to W3 flowing on the surface of the blade 2 are indicated by broken line arrows. The air flow W1 indicates the air flow flowing inside the blade 2 in the radial direction (on the side of the base 2b), the air flow W2 indicates the air flow flowing in the intermediate region in the radial direction of the blade 2 (the intermediate region between the side of the base 2b and the side of the outer peripheral edge 2a), and the air flow W3 indicates the air flow flowing outside the blade 2 in the radial direction (on the side of the outer peripheral edge 2a).
[0016] As shown in FIG. 3, in the impeller 3 according to the conventional example, there is no warped portion rising from the upstream side (the back side of the paper surface in FIG. 3) toward the downstream side (the front side of the paper surface in FIG. 3) along the outer peripheral edge 2a of the blade 2. Therefore, when the impeller 3 rotates in the rotational direction V to generate an air flow, a centrifugal force acts on the air flow W3 flowing outside in the radial direction, and the air flow W3 flowing along the surface of the blade 2 directly flows out from the outer peripheral edge 2a to the outside in the radial direction. When the air flow W3 flowing out from the outer peripheral edge 2a occurs in this way, the original performance of the fan cannot be exhibited, and there is a risk that the fan performance will deteriorate.
[0017] To explain the shape of the impeller 3 according to the embodiment of the present invention shown in Figure 8, Comparative Examples 1 to 3 will be described using Figures 4 to 6. Note that in Figures 4 to 7, only one of the multiple blades 2 is shown for ease of understanding.
[0018] Figure 4 is a plan view showing a part of the impeller 3 according to Comparative Example 1. In the impeller 3 of Comparative Example 1 shown in Figure 4, a curved portion 10 is provided that rises along the outer peripheral edge 2a of the blade 2 from the upstream side (the far side of the page in Figure 4) to the downstream side (the near side of the page in Figure 4). In Figure 4, point A is defined as the end of the leading edge 2c of the blade 2 on the base 2b side, point A' as the end of the leading edge 2c on the outer edge 2a side, point C as the end of the trailing edge 2d on the base 2b side, and point C' as the end of the trailing edge 2d on the outer edge 2a side.
[0019] Figure 5 is a cross-sectional view of the impeller 3 shown in Figure 4. As shown in Figure 5, the upstream surface of the blade 2 is composed of a curved surface extending radially outward from the base 2b. On the outer circumference of the blade 2, a curved portion 10 is provided where the curvature of the curved surface extending from the base 2b of the blade 2 changes, causing it to rise towards the upstream side. The point on the upstream surface of the blade 2 where the curvature of the curved surface extending from the base 2b of the blade 2 changes is called the starting position 11 of the curved portion 10. Returning to Figure 4, we define the end on the front edge 2c side of the starting position 11 of the curved portion 10 as point a, and the end on the rear edge 2d side of the starting position 11 of the curved portion 10 as point c, and the starting position 11 of the curved portion 10 is shown by a dashed line from point a to point c.
[0020] As shown in Figure 4, the curved portion 10 is provided from the leading edge 2c to the trailing edge 2d of the blade 2. The starting position 11 of the curved portion 10 (dashed line from point a to point c) is approximately an arc shape along the outer edge 2a.
[0021] Figure 6 is a plan view showing a part of the impeller 3 according to Comparative Example 2. Similar to Figure 4, points A, A', C, C', a, and c are defined, and the starting position 11 of the curved portion 10 is indicated by a dashed line from point a to point c.
[0022] As shown in Figure 6, in Comparative Example 2, point a coincides with point A', and the leading edge 2c does not have a curved portion 10.
[0023] Figure 7 is a plan view showing a part of the impeller 3 according to Comparative Example 3. Similar to Figure 4, points A, A', C, C', a, and c are defined, and the starting position 11 of the curved portion 10 is indicated by a dashed line from point a to point c.
[0024] As shown in Figure 7, in Comparative Example 3, point c coincides with point C', and the trailing edge 2d does not have a curved portion 10.
[0025] The shape of the impeller 3 according to an embodiment of the present invention will be described below with reference to Figure 8.
[0026] Figure 8 is a plan view showing a part of the impeller 3 according to an embodiment of the present invention. Similar to Figure 4, points A, A', C, C', a, and c are defined, and the starting position 11 of the curved portion 10 is indicated by a dashed line from point a to point c.
[0027] As shown in Figure 8, in the impeller 3 according to this embodiment, the starting position 11 of the curved portion 10 is a convex curve that protrudes radially outward. Here, the vertex of the convex curve is defined as point b, and the point where a virtual line extending radially outward along the shape of the blade 2 through point b intersects the outer edge 2a is defined as point B'. Here, point b is set such that the length of the curve from point A' to point a is longer than the length of the curve from point B' to point b, and the length of the curve from point B' to point b is shorter than the length of the curve from point C' to point c.
[0028] As explained in Figure 3, in an axial flow fan without the curved section 10, the airflow W3 flows out from the outer edge 2a. Therefore, as shown in Figure 4, simply providing a curved section 10 with a starting position 11 extending along the outer edge 2a is insufficient, as in environments with high static pressure, such as when rotating at high rotational speeds, would cause the airflow W3 to overflow the curved section 10 and flow out from the outer edge 2a. The inventors therefore investigated how to suppress the outflow of airflow W3 from the outer edge 2a by devising the shape of the starting position 11 of the curved section 10.
[0029] First, the inventors considered providing a curved portion 10 with the shape shown in Figure 6. In the shape shown in Figure 4, the airflow W3 tends to flow out from the rear of the blade 2 (near the trailing edge 2d). Therefore, they thought that by providing a curved portion 10 at the rear of the blade 2 as shown in Figure 6, it would be possible to suppress the outflow of the airflow W3 from the outer peripheral edge 2a while ensuring the curved portion 10 is of the minimum size. However, they found that with the blade 2 shown in Figure 6, the airflow W3 that hits the blade 2 flows out radially outward from the outer peripheral edge 2a, preventing the blade 2 from efficiently capturing air and making it difficult to improve the performance of the axial flow fan.
[0030] Next, the inventors considered providing a curved portion 10 with the shape shown in Figure 7. As shown in Figure 7, if a curved portion 10 is provided in front of the blade 2 (near the leading edge 2c), the airflow W3 that hits the blade 2 will be less likely to flow out from the front of the outer edge 2a, and it seems that an ideal flow can be achieved to some extent. However, the curved portion 10 has a shape different from the original shape of the blade 2, and if the curved portion 10 is made larger, the original amount of work done by the blade 2 will decrease accordingly. As a result, the inventors found that the amount of air that can be generated by the axial flow fan decreases because the overall amount of work done by the blade 2 decreases.
[0031] Therefore, the inventors considered providing a curved portion 10, as shown in Figure 8, that would prevent the airflow W3 from flowing out from the outer edge 2a and minimize the reduction in the work done by the blade 2. In the blade 2 having the curved portion 10 shown in Figure 8, the curved portion 10 is made large at the leading edge 2c of the blade 2, which is the air inlet. In other words, the length from point A' to point a is made large. With this large curved portion 10, the leading edge 2c of the blade 2 can give the airflow W3 a strong vector that flows backward. In the circumferential middle section of the blade 2, the size of the curved section 10 is reduced, allowing the airflow W3 that flows into this middle section to flow backward with the same momentum. As the airflow W3 flowing through the middle section gradually gains a stronger radially outward vector due to centrifugal force, gradually increasing the curvature of the section 10 from the middle section to the trailing edge 2d suppresses the outflow of the airflow W3 radially outward from the outer edge 2a. By providing a curved portion 10 of this shape, it is possible to minimize the area of the curved portion 10 while suppressing the outflow of the airflow W3 from the outer edge 2a.
[0032] Furthermore, the starting position 11 of the curved portion 10 at the leading edge 2c of the blade 2 may be located radially inward from the starting position 11 of the curved portion 10 at the trailing edge 2d of the blade 2. At the leading edge 2c of the blade 2, which is the air inlet for the blade 2, a stronger vector can be imparted to the airflow W3 that flows backward.
[0033] Next, we will describe the measurement results of the static pressure-airflow characteristics (hereinafter referred to as PQ characteristics) of axial flow fans using the conventional impeller 23, the impellers 33, 43, and 53 of Comparative Examples 1 to 3, and the impeller 3 of this embodiment, respectively.
[0034] Figure 9 is a graph showing the PQ characteristics of axial flow fans using each impeller. The horizontal axis represents airflow rate, and the vertical axis represents static pressure. For the conventional impeller 23, the impellers 33, 43, and 53 of Comparative Examples 1-3, and the impeller 3 of the embodiment of the present invention, the airflow rate and static pressure were measured when driven at a predetermined amount of power. As shown in Figure 9, a specific airflow rate (for example, 3 m³) 3 When the axial flow fan was driven to output ( / min), the static pressure increased in the following order: the conventional axial flow fan using impeller 23 (approximately 70 Pa), the axial flow fans using impellers 33, 43, and 53 in Comparative Examples 1-3 (approximately 90 Pa), and the axial flow fan using impeller 3 of this embodiment (95 Pa or more). Despite the same amount of power being supplied to each axial flow fan, the axial flow fan of this embodiment had the highest static pressure, confirming that the axial flow fan of this embodiment is the most efficient.
[0035] Next, the effect of changing the position of point b on power consumption in an axial flow fan having the impeller of this embodiment shown in Figure 8 will be explained using Figure 10. The relative position r of point b on the convex curve at the starting position 11 of the curved portion 10 will be expressed as the ratio of the length Y of the convex curve from point a to point b to the total length X of the convex curve (r = Y / X). r varies between 0 and 1.
[0036] Figure 10 is a graph showing the measured power consumption when an arbitrary amount of power was applied to each axial flow fan, so that impellers set to r=0.2, 0.4, and 0.6 each had similar PQ characteristics. Specifically, first, the power consumption was measured for an axial flow fan with an impeller of r=0.2 when an arbitrary amount of power was applied to change the PQ characteristics and airflow. Next, for an axial flow fan with an impeller of r=0.4, the power consumption was measured at a specific airflow (e.g., 1 m³). 3 At an output of 0-6 m / min, power was supplied to achieve the static pressure (e.g., 120 MPa) at the airflow rate indicated by an axial flow fan with an impeller of r=0.2. The power consumption at this time was measured. In this way, the airflow rates were measured from 0 to 6 m / min. 3 The power consumption was measured when the same static pressure was obtained over a period of time ( / min). Similarly, the power consumption was measured for an axial flow fan with an impeller set to r=0.6.
[0037] Figure 10 shows r An axial fan with an impeller set to =0.4 can achieve similar PQ characteristics with less power consumption than other axial fans. of This shows that Figure 10 is, r An axial flow fan with an impeller set to =0.4, r This demonstrates better power efficiency compared to an axial fan with an impeller set to =0.2 or 0.6.
[0038] Furthermore, we examined the range of b for which an efficient axial fan can be realized. Prior to such examination, we confirmed the relationship between the PQ characteristics and power consumption when point b was changed. Figure 10 shows that for r = 0.2, 0.4, and 0.6, the dashed lines are arranged at similar intervals and indicate that, under operating conditions with the same PQ characteristics, the change in power consumption with respect to the change in air volume is similar. Therefore, among various PQ characteristics, we focused on the power consumption when showing the PQ characteristics at free air (no-load state) as a representative and examined the optimal value of r. Figure 11 shows the results of measuring the power consumption at free air when r was varied. As shown in Figure 11, when 0 < r ≤ 0.6 was set, the free air power decreased. In particular, when 0.2 ≤ r ≤ 0.6 was set, it was confirmed that the free air power became 3.5 W Yo even smaller. In Figure 11, the power consumption at free air was measured and the optimal range of r was discussed. Such an optimal range of r is the same for other operating conditions as well. This is because, in Figure 10, it has been confirmed that the power changes similarly as the operating conditions change. Therefore, from Figure 11, it is preferable to set 0 < r ≤ 0.6 for any operating condition, and particularly, it is more preferable to set 0.2 ≤ r ≤ 0.6.
[0039] As described above, the embodiments of the present invention have been explained, but it is needless to say that the technical scope of the present invention should not be construed in a limited manner by the description of this embodiment. This embodiment is merely an example, and it is understood by those skilled in the art that various modifications of the embodiments are possible within the scope of the invention described in the claims. The technical scope of the present invention should be determined based on the scope of the invention described in the claims and its equivalent scope.
Explanation of Signs
[0040] 1 Axial fan 2 Blades 2a Outer peripheral edge 2b Root 2c leading edge 2d trailing edge 3 Impellers 4 motors 5 Housing 6 spokes 8 rotation axes 9 Hubs 10 Curved section 11 Starting position 51 Inner wall V rotation direction W Airflow direction W1, W2, W3 airflow
Claims
1. An axial flow fan having multiple blades that generates an airflow from the intake side to the discharge side, The aforementioned feathers are, The outer edge of the aforementioned blade is provided with a curved portion that rises toward the suction side, When viewed from the suction side, the starting position of the curved portion provided along the outer edge is a convex curve that protrudes radially outward. When viewed from the intake side, if the total length of the convex curve is X, then the length Y from the leading edge of the blade to the vertex of the convex curve is 0 < Y ≤ 0.6X. An axial flow fan wherein the starting position of the curvature at the leading edge is located radially inward from the starting position of the curvature at the trailing edge of the blade.
2. An axial flow fan according to claim 1, wherein 0.2X ≤ Y.