Blower fan

Abstract

To provide a blower fan capable of suppressing noise more accurately.SOLUTION: A blower fan 10 comprises a hub 20 arranged on an axis of rotation of the fan, a plurality of blades 30 formed to extend outward from an outer periphery of the hub 20, and an annular ring part 40 provided to couple respective tip parts 32 of the plurality of blades 30. At a tip part of a blade 30, a serration 34 is formed which suppresses an air flow from the blade 30 from separating. The blade 30 is so shaped to direct the flow direction of air passing by the blade 30 to a serration 34 of an adjacent blade arranged behind the blade 30 in a fan rotating direction F.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a blower fan. [Background technology]

[0002] A conventional blower fan is described in the following Patent Document 1. This blower fan includes a hub attached to a drive motor, a number of blades attached to the hub, and a ring portion attached to connect the tips of the blades. Each blade has serrations consisting of a number of triangular protrusions on its leading edge from the center to the leading edge. By providing the serrations on the leading edge of the blade, it becomes difficult for the airflow to diverge on the negative pressure surface of the blade when the blower fan rotates, and this makes it possible to suppress the generation of noise. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5880288 Summary of the Invention [Problem to be solved by the invention]

[0004] In the blower fan described in Patent Document 1, serrations are formed from the center to the tip of the blade, but no serrations are formed at the base end of the blade, so the air flow is likely to diverge on the negative pressure surface at the base end of the blade, which is a cause of noise generation when the blower fan rotates.

[0005] The present disclosure has been made in consideration of the above circumstances, and has an object to provide a blower fan that can more accurately suppress noise while maintaining air volume. [Means for solving the problem]

[0006] The blower fan that solves the above problem is a blower fan (10) that rotates in the fan rotation direction around a predetermined fan rotation axis, and includes a hub (20) arranged on the fan rotation axis, a plurality of blades (30) formed to extend outward from the outer periphery of the hub, and an annular ring portion (40) provided to connect the tips (32) of the plurality of blades. A separation suppression structure (34, 50, 51) that suppresses separation of airflow from the blade is formed at the tip of the blade. The blade has a shape that directs the flow direction of air passing through the blade toward the separation suppression structure of an adjacent blade that is arranged behind the blade in the fan rotation direction. The end of the blade that is connected to the outer periphery of the hub is defined as the base end (31), a line that is perpendicular to the fan rotation axis and passes through the center point of the base end of the blade in the fan rotation direction is defined as the reference line (m20), a line that connects the center point of the width of the blade in the fan rotation direction from the base end to the tip end of the blade is defined as the center line of the blade (m30), a line that is perpendicular to the fan rotation axis and passes through a predetermined position on the center line of the blade is defined as a predetermined position line (n11, n12), the angle that the predetermined position line makes with the reference line is defined as the skew angle at the predetermined position of the blade, and the skew angle when the predetermined position line is deviated from the reference line in the fan rotation direction is expressed as a positive value, and the skew angle when the predetermined position line is deviated from the reference line in the opposite direction to the fan rotation direction is expressed as a negative value, then the blade has a bent portion (36) in a portion closer to the base end than the center between the base end and the tip end. The blade has a shape that directs the flow of air passing through it toward the deviation prevention structure of the adjacent blade, such that the skew angle gradually increases from the base end to the bend, reaches a maximum value at the bend, gradually decreases from the bend to the tip, and becomes negative at the tip.

[0007] With this configuration, air that has passed through a given blade is more likely to flow toward the separation suppression structure of the adjacent blade disposed behind that blade, thereby enhancing the effectiveness of the separation suppression structure, thereby making it possible to more accurately suppress noise while maintaining air volume. The above means and the symbols in parentheses in the claims are merely examples showing the correspondence with specific means described in the embodiments described later. Effect of the Invention

[0008] According to the blower fan of the present disclosure, it is possible to more accurately suppress noise while maintaining the air volume. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a front view showing the front structure of a blower fan according to a first embodiment. [Diagram 2] FIG. 2 is an enlarged view showing an enlarged structure of the blade of the first embodiment. [Diagram 3] FIG. 3 is a graph showing the relationship between the blade pitch and the skew angle of the blade of the first embodiment. [Figure 4] FIG. 4 is a graph showing the relationship between the blade pitch and the inclination of the skew angle of the blade in the first embodiment. [Diagram 5]FIG. 5 is a cross-sectional view showing a cross-sectional structure taken along line VV in FIG. [Figure 6] FIG. 6 is a graph showing the relationship between the blade pitch and the blade chord length of the blade of the first embodiment. [Figure 7] FIG. 7 is an enlarged view showing an enlarged structure of the blade of the first embodiment. [Figure 8] FIG. 8 is a front view showing the front structure of the blower fan according to the first embodiment. [Figure 9] FIG. 9 is a diagram illustrating a schematic view of an air flow in the blade of the first embodiment. [Figure 10] FIG. 10 is a diagram illustrating a schematic view of the air flow around the serrations in the first embodiment. [Figure 11] FIG. 11 is a front view showing the front structure of the blower fan according to the second embodiment. [Figure 12] FIG. 12 is an enlarged view showing an enlarged structure of a blade according to another embodiment. [Figure 13] FIG. 13 is an enlarged view showing an enlarged structure of a blade according to another embodiment. [Figure 14] FIG. 14 is an enlarged view showing an enlarged structure of a blade according to another embodiment. [Figure 15] FIG. 15 is an enlarged view showing an enlarged structure of a blade according to another embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of a blower fan will be described with reference to the drawings. To facilitate understanding of the description, the same components in the various drawings will be denoted by the same reference numerals as much as possible, and duplicated description will be omitted. First Embodiment First, a description will be given of a blower fan 10 according to a first embodiment shown in Fig. 1. This blower fan 10 rotates about a fan rotation axis m10 in the direction indicated by arrow F, thereby generating an airflow in a direction along the fan rotation axis m10. The blower fan 10 is made of resin or the like. The blower fan 10 includes a hub 20, blades 30, and a ring portion 40. Hereinafter, the direction indicated by arrow F will be referred to as the "fan rotation direction F," and the radial direction about the fan rotation axis m10 will be referred to as the "fan radial direction."

[0011] The hub 20 is provided on the fan rotation shaft m10, and is formed into a cylindrical shape with a bottom, centered on the fan rotation shaft m10. The blower fan 10 has a plurality of blades 30, specifically seven blades 30. The blades 30 are formed to extend from the outer periphery of the hub 20 outward in the fan radial direction. The blades 30 have a curved shape that protrudes in the fan rotation direction F. In the following, the end of the blade 30 that is connected to the hub 20 is referred to as a base end 31, and the opposite end is referred to as a tip end 32. The blades 30 have the same shape and are arranged at equal angular intervals β in the fan rotation direction F. That is, the blades 30 are arranged at equal pitches.

[0012] The ring portion 40 is formed in an annular shape centered on the fan rotation axis m10, and is provided so as to connect the tips 32 of the blades 30 together. In this blower fan 10, power from a motor (not shown) is transmitted to the hub 20, causing the hub 20 to rotate about the fan rotation axis m10 in the fan rotation direction F. This causes the blades 30 and the ring portion 40 to rotate integrally with the hub 20 in the fan rotation direction F.

[0013] Next, the shape of the blade 30 of this embodiment will be specifically described. 1, the blade 30 has a bent portion 36 at a portion closer to the base end 31 than the center between the base end 31 and the tip end 32. The bent portion 36 is formed so as to protrude in the fan rotation direction F. As a result, the blade 30 is formed into an L-shape as a whole.

[0014] Serrations 34 are formed on leading edge 33 in fan rotation direction F at tip 32 of blade 30. Serration 34 is made up of multiple triangular protrusions. Serration 34 functions as a separation suppression structure that suppresses separation of airflow from blade 30. The serrations 34 suppress separation of airflow from blade 30, making it possible to suppress noise generation.

[0015] 2, the center points at each position in the fan radial direction of the blade 30 can be defined as, for example, "C10," "C11," and "C12." "C10" is the center point of the width in the fan circumferential direction at the base end 31 of the blade 30. "C11" is the center point of the width in the fan circumferential direction at the tip end 32 of the blade 30 where no serrations 34 are provided. "C12" is the center point of the width of a portion of the blade 30 located on an imaginary circle VC11 of radius R11 centered on the fan rotation axis m10.

[0016] Using these center points C10 to C12, a reference line m20 of the blade 30 is defined as shown by a two-dot chain line in Fig. 2, and a blade center line m30 of the blade 30 is defined as shown by a two-dot chain line in Fig. 2. In other words, the reference line m20 is a line that is perpendicular to the fan rotation axis m10 and passes through the center point C10 of the base end 31 of the blade 30. The blade center line m30 is a line that connects the center points C10 to C12 of the blade 30 from the base end 31 to the tip end 32 of the blade 30.

[0017] Also, the angle that a line that is perpendicular to the fan rotation axis m10 and passes through a predetermined position on the blade center line m30 of the blade 30, for example, the lines n11 and n12 shown in FIG. 2, make with respect to the reference line m20 is defined as the skew angle θ at a predetermined position of the blade 30. The line n11 is a line that is perpendicular to the fan rotation axis m10 and passes through the position C11. The skew angle at the position C11 of the blade center line m30 of the blade 30 can be defined as the angle θ11 that this line n11 makes with respect to the reference line m20. The line n12 is a line that is perpendicular to the fan rotation axis m10 and passes through the position C12. The skew angle at the position C12 on the blade center line m30 of the blade 30 can be defined as the angle θ12 that this line n12 makes with respect to the reference line m20. In this embodiment, the lines n11 and n12 correspond to the predetermined position lines.

[0018] In this embodiment, the skew angle θ is expressed as a positive value when it is offset in the fan rotation direction F with respect to the reference line m20, i.e., the reference line m20 is set to "0°", and an angle offset in the opposite direction to the fan rotation direction F is expressed as a negative value. Therefore, the skew angle θ11 at position C11 of the blade 30 is a negative value, and the skew angle θ12 at position C12 of the blade 30 is a positive value.

[0019] The skew angle θ of each blade 30 changes from the base end 31 to the tip end 32 as shown in Fig. 3. Note that the blade pitch P in Fig. 3 is a parameter obtained by normalizing the radial position on the blade centerline m30 of the blade 30 to a value ranging from "0" to "1.0", with the radial position of the base end 31 being "0" and the radial position of the tip end 32 being "1.0". Therefore, the position on the blade centerline m30 of the blade 30 where the blade pitch P is "0.5" is the center of the blade centerline m30. Also, in Fig. 3, the blade pitch P corresponding to the bent portion 36 of the blade 30 is indicated by "Pc".

[0020] As shown in FIG. 3, in the region where the blade pitch P is from "0" to "Pc", as the blade pitch P increases, the skew angle θ of the blade 30 gradually increases. Then, at the bent portion 36 of the blade 30 where the blade pitch P is "Pc", the skew angle θ of the blade 30 takes a maximum value θmax. Also, in the region where the blade pitch P is from "Pc" to "1.0", as the blade pitch P increases, the skew angle θ of the blade 30 gradually decreases. Then, at the tip portion 32 of the blade 30 where the blade pitch P is "1.0", the skew angle θ of the blade 30 takes a negative value "-θa". Each blade 30 has a shape in which the skew angle θ changes with respect to the blade pitch P as shown in FIG. 3.

[0021] The amount of change Δθ in the skew angle θ when the blade pitch P changes from "Pc" to "1.0", in other words, the amount of change in the skew angle θ from the bent portion 36 of the blade 30 to the tip 32, is set in the range of "25°" to "40°." The bent portion 36 is provided in the blade 30 within a range E where the blade pitch P is from "0.2" to "0.4."

[0022] Fig. 4 shows the relationship between the inclination α of the skew angle θ and the blade pitch P shown in Fig. 3. As shown in Fig. 4, in the region of the blade 30 where the blade pitch P indicates "Pc-0.1" to "Pc+0.1", the amount of change Δα in the inclination of the skew angle θ of the blade 30 is set in the range from "60[°]" to "90[°]".

[0023] Fig. 5 shows the cross-sectional structure of the blade 30 taken along line VV shown in Fig. 2. As shown in Fig. 5, when the length of a straight line n20 connecting the leading edge 33 and the trailing edge 35 in the cross section of the blade 30 is taken as the "chord length LW", the chord length LW with respect to the blade pitch P is set as shown in Fig. 6. As shown in Fig. 6, the chord length LW2 of the bent portion 36 of the blade 30 is longer than the chord length LW1 of the base end 31 of the blade 30, and the chord length LW3 of the tip end 32 of the blade 30 is longer than the chord length LW2 of the bent portion 36 of the blade 30.

[0024] In FIG. 7, the inner part of the blade 30, which is a part from the base end 31 to the bent part 36, is indicated by the reference numeral 37, and the outer part of the blade 30, which is a part from the bent part 36 to the tip end 32, is indicated by the reference numeral 38. In addition, in FIG. 7, a straight line connecting one end 37a located at the base end 31 and the other end 37b located at the bent part 36 in the front edge part 33 of the inner part 37 is indicated by a two-dot chain line u10. Hereinafter, the area vertically projected rearward in the fan rotation direction F from this two-dot chain line u10 is referred to as a "rear wind flow area Aw". In addition, a blade disposed rearward in the fan rotation direction F with respect to any one blade 30 is referred to as an "adjacent blade 30a". By forming each blade 30 as shown in FIG. 4 to FIG. 6, each blade 30 has a shape in which the rear wind flow area Aw does not overlap the entire area of ​​the front edge part 33 of the adjacent blade, as shown in FIG. 8.

[0025] Next, the operation and effects of the blower fan 10 of the present embodiment will be described. In the blower fan 10 of this embodiment, when the blower fan 10 rotates, an airflow is formed as shown by the arrows in Fig. 9. That is, the flow direction W1 of the air that has passed through the inner portion 37 of the blade 30 is obliquely oriented toward the ring portion 40. Moreover, the flow direction W2 of the air that has passed through the outer portion 38 of the blade 30 is oriented toward the outer portion 38 of the adjacent blade 30a. As a result, the air that has passed through the blade 30 is concentrated near the serrations 34 of the adjacent blade 30a, so that the noise reduction effect of the serrations 34 can be efficiently obtained. As a result, it is possible to obtain a noise reduction effect that is equal to or greater than the sum of the noise reduction effect achieved by the serrations alone and the noise reduction effect achieved by the blades alone.

[0026] According to the blower fan 10 of the present embodiment described above, the following actions and advantages (1) to (4) can be obtained. (1) The blade 30 has a shape that directs the flow of air passing through the blade 30 toward the serrations 34 of the adjacent blade 30a. With this configuration, the air that has passed through the blade 30 tends to flow toward the serrations 34 of the adjacent blade 30a, thereby enhancing the effect of the serrations 34. This makes it possible to more accurately suppress noise while maintaining the air volume.

[0027] 3, blade 30 has a shape in which skew angle θ gradually increases from base end 31 to bend 36, reaches a maximum value at bend 36, gradually decreases from bend 36 to tip 32, and has a negative value at tip 32. This configuration makes it easy to realize a shape that directs the flow of air passing through blade 30 toward serrations 34 of adjacent blade 30a.

[0028] (3) As shown in Figure 7, the blade 30 has a shape in which the rear airflow region Aw of the inner portion 37 does not overlap the entire area of ​​the leading edge portion 33 of the adjacent blade 30a. With this configuration, air passing through the inner portion 37 of the blade 30 is easily concentrated in the serrations 34 of the adjacent blade 30a, thereby further improving the effect of the serrations 34.

[0029] (4) The serrations 34, which are made up of multiple triangular projections, are used as a separation suppression structure that suppresses the separation of the airflow from the blades 30. With this configuration, as shown by the arrows in Fig. 10, the air that is concentrated at the serrations 34 of the blades 30 forms an airflow that suppresses the air that separates from the negative pressure surface of the blades 30, so that the separation of the airflow from the negative pressure surface of the blades 30 can be more accurately suppressed. This improves the noise reduction effect.

[0030] <Second embodiment> Next, a blower fan 10 according to a second embodiment will be described. The following description will focus on the differences from the blower fan 10 according to the first embodiment. 11, in the blower fan 10 of this embodiment, when the angular intervals at which the blades 30 are arranged are defined as "α1 to α7," all of the angles α1 to α7 are set to different values. That is, the blades 30 are arranged at unequal pitches.

[0031] The blower fan 10 has first blades 30b in which the rear air flow region Aw of the inner portion 37 does not overlap the entire area of ​​the leading edge portion 33 of the adjacent blade, and second blades 30c in which the rear air flow region Aw of the inner portion 37 overlaps the leading edge portion 33 of the adjacent blade. The blower fan 10 has four first blades 30b and three second blades 30c. Thus, the number of first blades 30b is greater than the number of second blades 30c.

[0032] According to the blower fan 10 of the present embodiment, in addition to the actions and advantages described in (1) to (4) above, the actions and advantages described in (5) below can be obtained. (5) The blades 30 are arranged at different angular intervals from one another in the fan rotation direction F. This configuration makes it possible to prevent a sound of a specific frequency from being emphasized when the blower fan 10 rotates, thereby suppressing noise.

[0033] <Other embodiments> The above embodiment can also be implemented in the following manner. The position of the serrations 34 on the blade 30 can be changed as desired. For example, the serrations 34 may be formed on the trailing edge 35 of the tip 32 of the blade 30 as shown in Fig. 12, or may be formed on both the leading edge 33 and the trailing edge 35 of the tip 32 of the blade 30 as shown in Fig. 13.

[0034] The separation suppression structure for suppressing separation of the airflow from the blade 30 is not limited to the serrations 34, but may be a recess 50 shown in FIG. 14 or a protrusion 51 called a vortex generator shown in FIG. 15, etc. The present disclosure is not limited to the above specific examples. Any design modifications made by a person skilled in the art to the above specific examples are also included within the scope of the present disclosure as long as they have the features of the present disclosure. The elements of each of the above specific examples, as well as their arrangements, conditions, shapes, etc., are not limited to those exemplified and can be modified as appropriate. The elements of each of the above specific examples can be combined in different ways as appropriate, as long as no technical contradictions arise. [Explanation of symbols]

[0035] Aw: Rear wind flow area m20: Reference line m30: wing center line n11,n12:Position line 10: Blower fan 20: Hub 30: Blade 30b: First Blade 30c: 2nd blade 31: Proximal end 32:Tip 34: Serration (anti-displacement structure) 36: Bend 37:Inner part 40: Ring section 50: Concave (anti-disengagement structure) 51: Convex part (anti-displacement structure)

Claims

1. A blower fan (10) that rotates in a fan rotation direction around a predetermined fan rotation axis, A hub (20) disposed on the fan rotation shaft; a plurality of blades (30) formed to extend outwardly from the outer periphery of the hub; and a circular ring portion (40) provided to connect the tip portions (32) of the plurality of blades, A separation suppression structure (34, 50, 51) that suppresses separation of the air flow from the blade is formed at the tip of the blade, The blade has a shape that directs a flow direction of air passing through the blade toward the separation suppression structure of an adjacent blade that is disposed behind the blade in the fan rotation direction, The end of the blade that is connected to the outer periphery of the hub is called a base end (31); A line perpendicular to the fan rotation axis and passing through the center point of the base end of the blade in the fan rotation direction is defined as a reference line (m20), A line connecting a center point of the width of the blade in the fan rotation direction from the base end to the tip end of the blade is defined as a center line (m30) of the blade, A line perpendicular to the fan rotation axis and passing through a predetermined position on the center line of the blade is defined as a predetermined position line (n11, n12), The angle that the predetermined position line makes with respect to the reference line is defined as a skew angle at the predetermined position of the blade; When the skew angle is expressed as a positive value when the predetermined position line is deviated from the reference line in the fan rotation direction, and when the skew angle is expressed as a negative value when the predetermined position line is deviated from the reference line in the opposite direction to the fan rotation direction, The blade is A bent portion (36) is provided at a portion closer to the base end than to a center between the base end and the tip end, The blade has a shape that directs the flow direction of air passing through the blade toward the deviation suppression structure of the adjacent blade, the skew angle gradually increases from the base end portion to the bent portion, exhibits a maximum value at the bent portion, the skew angle gradually decreases from the bent portion to the tip portion, and the skew angle has a negative value at the tip portion. Blower fan.

2. When a portion of the blade from the base end to the bent portion is defined as an inner portion (37), and a region of a front edge portion of the inner portion vertically projected rearward in the fan rotation direction from a straight line connecting one end located at the base end and the other end located at the bent portion is defined as a rear wind flow region (Aw), The blade has a shape in which the rear wind flow area of ​​the inner portion does not overlap the entire area of ​​the leading edge of the adjacent blade. The blower fan according to claim 1.

3. The blades are arranged at different angular intervals in the fan rotation direction. The blower fan according to claim 2.

4. The blades include a first blade (30b) in which the rear wind flow region of the inner portion does not overlap the entire area of ​​the leading edge portion of the adjacent blade, and a second blade (30c) in which the rear wind flow region of the inner portion overlaps the leading edge portion of the adjacent blade, The number of the first blades is greater than the number of the second blades. The blower fan according to claim 3.

5. The amount of change in the skew angle from the bent portion to the tip of the blade is set in a range of "25[°]" to "40[°]", When the position of the base end portion is defined as "0" and the position of the tip end portion is defined as "1", and the position on the center line of the blade is normalized to a value in the range from "0" to "1", the blade pitch is defined as: The bent portion is provided in a region of the blade where the blade pitch is from "0.2" to "0.4", When the blade pitch corresponding to the position of the bend is "Pc", In the region of the blade where the blade pitch is from "Pc-0.1" to "Pc+0.1", the amount of change in the inclination of the skew angle of the blade is set to a range from "60[°]" to "90[°]". The blower fan according to any one of claims 1 to 4.

6. When the width of a cross section perpendicular to the center line of the blade is defined as a chord length of the blade, The chord length of the bent portion of the blade is longer than the chord length of the base end of the blade, and the chord length of the tip end of the blade is longer than the chord length of the bent portion of the blade. The blower fan according to any one of claims 1 to 5.

7. The plurality of blades includes seven blades. The blower fan according to any one of claims 1 to 6.

8. Each of the blades has the same shape. The blower fan according to any one of claims 1 to 7.

9. The separation prevention structure is a serration (34) consisting of a plurality of triangular protrusions. The blower fan according to any one of claims 1 to 8.

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