CN216478021U - Impeller, axial fan, and information processing device - Google Patents

Abstract

The utility model provides an impeller, an axial fan and an information processing device. An impeller of an axial flow fan rotates around a central axis, the impeller having a hub at a center portion thereof, blades extending radially outward from the hub and having a blade tip portion on a front side in a rotation direction and a blade tip portion on a rear side in the rotation direction, the blade tip portion being provided at a position on one axial side of the blade tip portion, a surface on the other axial side of the blades being a concave surface curved to one axial side with respect to a blade chord connecting the blade tip portion and the blade tip portion in a circumferential direction, the surface on the one axial side of the blades having a first convex surface and a second convex surface extending from a predetermined position in the circumferential direction of the hub in a direction away from the central axis.

Description

Impeller, axial fan, and information processing device

Technical Field

The utility model relates to an impeller, an axial fan and an information processing device.

Background

The axial flow fan causes air to flow in an axial direction by rotating an impeller having a plurality of blades. Conventionally, a technique of forming a blade into a curved shape for the purpose of suppressing noise of a fan is known (see patent document 1).

Patent document 1: japanese laid-open patent publication No. 2008-051074

One of the performances of the axial fan is determined by a PQ characteristic (static pressure-air volume characteristic). In an axial flow fan requiring a high air volume, it is considered to increase the installation angle of blades with respect to the rotation axis of the impeller. However, the blade having a large installation angle has a problem of having a surge region in which a part of the PQ characteristic is reduced. In the surge region, the flow of air generates a turbulent surge phenomenon in front of and behind the rotating blades. Due to this phenomenon, the amount of air conveyed by the rotation of the blades decreases, and therefore the air volume Q decreases in a state where the pressure P cannot be increased. When the blade is curved as in patent document 1, there is room for improvement in surge.

SUMMERY OF THE UTILITY MODEL

The utility model aims to provide an impeller which improves surging and obtains high PQ characteristic.

An exemplary embodiment of the present disclosure is an impeller of an axial fan that rotates about a center axis, the impeller including a hub at a center portion thereof, and a blade extending radially outward from the hub and including a blade tip portion on a rotational direction front side and a blade tip portion on a rotational direction rear side, the blade tip portion being provided at a position on one axial side of the blade tip portion, a surface on the other axial side of the blade being a concave surface that is curved on one axial side with respect to a blade chord that connects the blade tip portion and the blade tip portion in a circumferential direction, the surface on the one axial side of the blade including a first convex surface and a second convex surface that are continuous from a predetermined position in the circumferential direction of the hub in a direction away from the center axis.

An exemplary embodiment of the present disclosure is the impeller described in the preceding paragraph, wherein the surface of the other axial side of the blade is located on one axial side of the blade chord, and a distance between the surface of the other axial side of the blade and the blade chord is farthest in a circumferential direction from a side of the other axial side of the blade closest to the tip end of the blade in a middle of the blade.

An exemplary embodiment of the present disclosure is the impeller of the preceding item, wherein the first convex surface is provided on a side of the blade tip portion, and the second convex surface is provided on a side of the blade trailing end portion.

An exemplary embodiment of the present disclosure is the impeller of the preceding paragraph, wherein the second convex surface extends continuously from the hub to a radially outer end of the blade.

An exemplary embodiment of the present disclosure is the impeller of the preceding item, wherein an apex of the second convex surface as viewed in the circumferential direction is elongated in a direction away from the central axis at a constant interval from the blade rear end portion.

An exemplary embodiment of the present disclosure is the impeller of the preceding item, wherein an apex of the second convex surface extends in a direction away from the central axis at a distance equal to the blade chord.

An exemplary embodiment of the present disclosure is the impeller described in the foregoing, characterized in that the impeller has a plurality of the blades, and intervals of the second convex surfaces from rear end portions of the blades are different among the plurality of blades.

An exemplary embodiment of the present disclosure is the impeller of the preceding item, characterized in that it has a plurality of the blades in which the distances of the second convex surfaces from the chord of the blade are different from each other.

An exemplary embodiment of the present disclosure is an axial flow fan in which an intake side fan having the impeller described above and an exhaust side fan are arranged in series.

An exemplary embodiment of the present disclosure is an information processing apparatus having the axial flow fan described in the preceding paragraph.

According to the present invention, an impeller having improved surge and high PQ characteristics can be provided.

Drawings

Fig. 1 is a perspective view showing a fan according to a first embodiment of the present invention.

Fig. 2 is a perspective view showing fan 10 in a direction in which exhaust fan 200 is located forward relative to intake fan 100.

Fig. 3 is a perspective cross-sectional view of the fan 10 taken along a plane perpendicular to the Z-axis.

Fig. 4 is a plan view of impeller 120 viewed from the + Y side.

Fig. 5 is a side view of impeller 120 viewed from the + Z side.

Fig. 6 is a perspective view of impeller 120.

Fig. 7 is a diagram showing the PQ characteristic of the fan 10 in comparison with the conventional art.

Detailed Description

Hereinafter, a fan according to an embodiment of the present invention will be described with reference to the drawings. In the drawings below, in order to facilitate understanding of each structure, the actual structure may be different from the scale, the number, and the like of each structure.

In addition, in the drawings, an XYZ coordinate system is appropriately shown as a three-dimensional orthogonal coordinate system. In the XYZ coordinate system, the Y-axis direction is a direction parallel to the axial direction of the central axis J shown in fig. 1. The Z-axis direction is a vertical direction in fig. 1 in a radial direction with respect to the central axis J. The X-axis direction is a direction perpendicular to both the Z-axis direction and the Y-axis direction. In any of the X-axis direction, the Y-axis direction, and the Z-axis direction, one side indicated by an arrow shown in the drawing is set as a + side, and the opposite side is set as a-side.

In the following description, the positive side (+ Y side) in the Y axis direction is referred to as "front side" or "one side", and the negative side (-Y side) in the Y axis direction is referred to as "rear side" or "the other side". The rear side (the other side) and the front side (one side) are only names for explanation, and do not limit the actual positional relationship and direction. Unless otherwise specified, a direction parallel to the central axis J (Y-axis direction) is simply referred to as "axial direction", a radial direction about the central axis J is simply referred to as "radial direction", and a circumferential direction about the central axis J, that is, a direction around the central axis J (θ direction) is simply referred to as "circumferential direction". A side close to the central axis J is referred to as "radially inner side" in the radial direction, and a side far from the central axis J is referred to as "radially outer side". In the circumferential direction, one side indicated by an arrow shown in the drawing is set as a + side, and the opposite side is set as a-side. The positive side (+ θ side) in the circumferential direction is referred to as "one side", and the negative side (- θ side) in the circumferential direction is referred to as "the other side".

In addition, in the present specification, "extend in the axial direction" includes, in addition to a case of strictly extending in the axial direction (Z-axis direction), a case of extending in a direction inclined in a range of less than 45 ° with respect to the axial direction. In addition, in the present specification, "extend in the radial direction" includes, in addition to a case of extending strictly in the radial direction, that is, in a direction perpendicular to the axial direction (Z-axis direction), a case of extending in a direction inclined in a range of less than 45 ° with respect to the radial direction. In addition, "parallel" includes a case where the two are inclined within a range of an angle of less than 45 ° with respect to each other, in addition to a case where the two are strictly parallel.

[ first embodiment ] to provide a liquid crystal display device

< integral Structure >

Fig. 1 is a perspective view showing a fan according to a first embodiment of the present invention. The fan 10 is an axial flow fan. The fan 10 has a suction-side fan 100 and an exhaust-side fan 200. The fan 10 is configured by arranging an intake side fan 100 and an exhaust side fan 200 in series. The suction side fan 100 and the discharge side fan 200 are arranged in the axial direction.

Fig. 1 is a perspective view showing fan 10 in a direction in which suction-side fan 100 is located in front of discharge-side fan 200.

As shown in fig. 1, intake-side fan 100 includes impeller 120 rotatable about central axis J, and casing 101 disposed radially outward of impeller 120. The impeller 120 rotates in the circumferential direction indicated by the arrow a in fig. 1. One circumferential side is a rotational direction front side of the impeller 120, and the other circumferential side is a rotational direction rear side of the impeller 120.

Impeller 120 includes a hub 121 at a center portion thereof, and blades 122, 123, 124, 125, and 126 extending radially outward from hub 121.

When the impeller 120 rotates in the direction indicated by the arrow a, the surfaces of the blades 122, 123, 124, 125, and 126 on one axial side become negative pressure surfaces, and the surfaces on the other axial side become positive pressure surfaces.

The casing 101 houses the impeller 120. The housing 101 includes a cylindrical portion 103 extending in the direction of the central axis J, a flange portion 102 disposed on the other axial side of the cylindrical portion 103, and a flange portion 104 disposed on one axial side of the cylindrical portion 103.

Fig. 2 is a perspective view showing fan 10 in a direction in which exhaust fan 200 is located forward relative to intake fan 100.

As shown in fig. 2, the exhaust-side fan 200 includes an impeller 220 rotatable about a central axis J, and a casing 201 disposed radially outward of the impeller 220. The impeller 220 rotates in the other circumferential direction, which is the direction indicated by the arrow B in fig. 2. The other circumferential side is the rotational direction front side of the impeller 220, and the one circumferential side is the rotational direction rear side of the impeller 120.

The impeller 220 includes a hub 221 at a center portion thereof, and blades 222, 223, and 224 extending radially outward from the hub 221.

When the impeller 220 rotates in the direction indicated by the arrow B, the surfaces of the blades 222, 223, and 224 on one axial side become negative pressure surfaces, and the surfaces on the other axial side become positive pressure surfaces.

The casing 201 houses the impeller 220. The housing 201 includes a cylindrical portion 203 having a cylindrical shape extending in the direction of the central axis J, a flange portion 202 disposed on one axial side of the cylindrical portion 203, and a flange portion 204 disposed on the other axial side of the cylindrical portion 203.

The fan 10 is formed by axially facing and fixing the other axial surface of the flange portion 102 of the intake side fan 100 and the one axial surface of the flange portion 202 of the exhaust side fan 200 by, for example, bolts not shown.

In fan 10, impeller 120 rotates in one circumferential direction in the direction indicated by arrow a in fig. 1, and impeller 220 rotates in the other circumferential direction in the direction indicated by arrow B in fig. 2, thereby causing air to flow in the axial direction from one axial direction to the other axial direction. The rotation direction of the suction side fan 100 is opposite to the rotation direction of the discharge side fan 200. The fan 10 is a double counter-rotating fan.

Fig. 3 is a perspective cross-sectional view of the fan 10 taken along a plane perpendicular to the Z-axis. The cross-sectional plane of the cross-sectional view of fig. 3 is a position where the blade 122 can be seen in cross-section.

Suction-side fan 100 includes an impeller 120 and a motor, not shown, for rotating impeller 120. Impeller 120 has a hub 121 of a bottomed cylindrical shape having a bottom on one axial side and an opening on the other axial side. The hub 121 houses a motor. The other axial side of the motor is supported by the motor housing 161. The motor case 161 is a substantially disk-shaped member disposed on the opening portion side on the other axial side of the hub 121. The radially outer end of the motor case 161 is fixed to the case 101 via a rib 160. The rib 160 is provided in plurality in the circumferential direction. The motor housing 161, the ribs 160 and the housing 101 may be the same component.

The exhaust-side fan 200 includes an impeller 220 and a motor, not shown, for rotating the impeller 220. The impeller 220 has a hub 221 in the shape of a bottomed cylinder having a bottom on one axial side and an opening on the other axial side. The hub 221 houses a motor. One axial side of the motor is supported by the motor housing 261. The motor housing 261 is a substantially disk-shaped member disposed on the opening portion side on the other axial side of the hub 221. A radially outer end of the motor housing 261 is fixed to the housing 201 via a rib 260. The rib 260 is provided in plurality in the circumferential direction. The motor housing 261, the ribs 260, and the housing 201 may be the same component.

Impeller 120 includes blades 122, 123, 124, 125, and 126 extending radially outward from hub 121. The blades 122, 123, 124, 125, and 126 are arranged at equal intervals in the circumferential direction around the hub 121. The blades 122, 123, 124, 125, and 126 have the same shape and the same size. The present invention is not limited to this, and any interval among the blades 122, 123, 124, 125, and 126 arranged in the circumferential direction may be different. In addition, at least one of the shape and size of any one of the blades 122, 123, 124, 125, and 126 may be different from the other blades.

Hereinafter, the blade 122 will be described by taking a plurality of blades, such as the blades 122, 123, 124, 125, and 126, as a representative, and the description of the other blades will be omitted. In the present embodiment, the case where the number of the blades of the suction side fan 100 is 5 has been described, but the present invention is not limited to this. The number, shape, and size of the blades of the exhaust fan 200 are different from those of the intake fan 100, but the present invention is not limited thereto. The blades of the exhaust side fan 200 may be the same as those of the intake side fan 100.

The vane tip 122a of the vane 122 on the front side in the rotation direction of the impeller 120 is provided on one axial side of the vane rear end 122b on the rear side in the rotation direction. The surface 142, which is the axial one-side surface of the blade 122, has a plurality of convex surfaces extending from a predetermined position in the circumferential direction of the hub 121 in a direction away from the center axis J.

The convex surface has a first convex surface 151 disposed on the blade leading end portion 122a side and a second convex surface 152 disposed on the blade trailing end portion 122b side. The surface 142 has an inflection point 153 between the first convex surface 151 and the second convex surface 152 to smoothly connect a skirt of the first convex surface 151 and a skirt of the second convex surface 152.

In general, the shape of the blade is represented by: a blade chord which is a line connecting the tip end and the rear end of the blade, a blade thickness which is a distance between the upper surface of the blade and the lower surface of the blade, and a blade arc which is a line connecting the center position between the upper surface of the blade and the lower surface of the blade from the tip end to the rear end of the blade. Blade thickness and blade arc, represented by a smooth curve that evenly continues from the front end of the blade to the rear end of the blade, are well known.

In the blade 122, a surface 141 that is the other surface in the axial direction of the blade 122 is a concave surface that is curved to one side in the axial direction with respect to the blade chord 140. The surface 142, which is one axial surface of the blade 122, has a first convex surface 151 and a second convex surface 152 that extend in a direction away from the center axis J from a predetermined position in the circumferential direction of the hub 121. The change in blade thickness varies in the circumferential direction under the influence of the axial position of the blade upper surface, i.e., the surface 142 that is the surface on one side in the axial direction of the blade 122. The blade thickness of the blade 122 increases from the blade tip portion 122a toward the apex of the first convex surface 151, decreases from the apex of the first convex surface 151 toward the inflection point portion 153, increases from the inflection point portion 153 toward the apex of the second convex surface 152, and decreases from the apex of the second convex surface 152 toward the blade tip portion 122 b.

The blade arc in the blade 122 has an inflection point halfway in the blade. The pressure surface side of the blade is a smooth curve. However, the negative pressure surface side of the blade is curved by providing the second convex surface 152, and the blade arc is similarly curved. The positive pressure surface side of the blade is a smooth curve, but the negative pressure surface side of the blade is provided with a first convex surface 151, a second convex surface 152, and an inflection point portion 153, and the blade arc also has an inflection point in the same manner.

Fig. 4 is a plan view of impeller 120 viewed from the + Y side.

Fig. 5 is a side view of impeller 120 viewed from the + Z side.

Fig. 6 is a perspective view of impeller 120.

The surface 141 is located on the axial side of the blade chord 140. The distance between the surface 141 and the blade chord 140 is farthest in the circumferential direction from a position 140a that is a position in the middle, to a position 140b that is a position closer to the blade tip portion 122 a. That is, the axial position of the face 141 of the blade 122 is farthest from the blade chord 140 at the position 140b, gradually approaches the blade chord 140 as it approaches the blade leading end 122a, and gradually approaches the blade chord 140 as it approaches the blade trailing end 122 b. The surface 141 has no other irregularities and no inflection point.

The line 152a is a line connecting the apexes of the second convex surfaces 152 extending in a direction away from the central axis J. The line 152a continues at a constant spacing from the blade rear end 122 b. The plurality of blades 122, 123, 124, 125, and 126 may have different or the same second convex surface position and size.

Fig. 7 is a diagram showing the PQ characteristic of the fan 10 in comparison with the conventional art. In fig. 7, the vertical axis represents pressure (P) and the horizontal axis represents air volume (Q). Fig. 7 shows PQ characteristics obtained by fluid analysis. A first embodiment in fig. 7 shows the fan 10 shown in fig. 1. Fig. 7 shows a conventional fan having no second convex surface on one axial surface of the impeller. In fig. 7, the PQ characteristic of the fan 10 is shown by a solid line with a thick line, and the PQ characteristic of the conventional fan is shown by a solid line with a thin line. As shown in fig. 7, although the conventional fan can check the decrease in pressure P due to surge, the fan 10 according to the present embodiment can suppress the decrease in pressure P due to surge.

In the conventional vane, the positive pressure surface side (the other side in the axial direction) generates an axial air flow by pushing air by the vane. The air flowing on the positive pressure surface side of the blade accelerates as the inclination of the blade increases.

Further, the negative pressure surface side (axial direction side) can generate air flow along the negative pressure surface side of the blade. The air flowing on the negative pressure surface side of the blade accelerates as the inclination of the blade increases, and the pressure decreases. In the surge region, the flow is disturbed.

In the blade 122 of the present embodiment, on the negative pressure surface side (axial direction side), a line 152a connecting the apexes of the second convex surfaces 152 that extend in a direction away from the central axis extends at a constant interval from the blade rear end portion 122 b.

The flow of air on the negative pressure surface side accelerates from the blade tip portion 122a along the first convex surface 151 and toward the circumferential center portion. The pressure of the air may be reduced by acceleration to cause turbulence in the flow, but since there is a recess from the blade tip 122a to the center, the growth of the turbulence can be suppressed, and the flow does not grow into a large turbulence.

Further, the air on the negative pressure surface side is accelerated from the center portion along the second convex surface 152 and directed toward the blade rear end portion 122 b. The pressure of the air may be reduced by acceleration to cause turbulence of the flow, but since the distance from the center portion to the blade rear end portion 122b is short, it is possible to suppress the flow from growing into a large turbulence.

Further, the air flow on the negative pressure surface side at the blade rear end portion 122b passes through the convex portion on the rear side in the rotation direction, and the amount of the air flow in the same direction as the air flow on the positive pressure surface side increases, so that the turbulence at the time of joining at the blade rear end portion can be suppressed.

By changing the distance between the line 152a connecting the apexes of the second convex surfaces 152 and the blade rear end portions 122b in the radial direction and matching different air flows at the radial positions, the turbulence of the air may be further suppressed.

There are a plurality of vanes, and by varying the position and size of the second convex surface 152 on the negative pressure surface side, it is possible to suppress a decrease in the air volume (Q) in a wider pressure (P) range. When all of the plurality of blades have the same shape, the deterioration of the PQ characteristic can be suppressed at a specific pressure. On the other hand, the different shapes limit the effect of suppressing the reduction in the air volume under a specific pressure, but can suppress the reduction in the air volume over a wide pressure range.

Further, since the turbulence of the air flow generated by the respective blades affects each other, the second convex surfaces 152 different from each other are provided on the respective blade surfaces, so that the reduction of the pressure (P) and the air volume (Q) characteristics may be suppressed.

In particular, in the double counter-rotating fan, ribs (ribs 160 and 260) are provided at the axial center portion between the intake-side fan 100 and the exhaust-side fan 200. The turbulence of the air flow is further increased by the rib, and causes a decrease in PQ characteristics, noise, and vibration. According to the shape of the blade 122 of the intake-side fan 100 of the present embodiment, the flow of air can be suppressed from being greatly disturbed, and thus disturbance of air by the rib can be suppressed.

The fan 10 can be used as a cooling fan built in an information processing apparatus, for example. Examples of the information processing device include a mobile phone, a smart phone, a personal computer, and the like. In such an information processing apparatus, many components are housed in a small case for downsizing, and a passage of cooling air flow is narrowed. Therefore, the cooling fan requires high PQ characteristics, and the fan 10 described above is suitable.

< effects and effects of impeller 120 >

Next, the operation and effect of impeller 120 will be described.

In the above-described embodiment, the impeller of the axial fan rotates about a center axis, the impeller includes a hub at a center portion thereof, and the impeller includes blades extending radially outward from the hub and having a blade tip portion on a forward side in a rotation direction and a blade tip portion on a rearward side in the rotation direction, the blade tip portion is provided at a position on one axial side of the blade tip portion, a surface on the other axial side of the blade is a concave surface curved to one axial side with respect to a blade chord connecting the blade tip portion and the blade tip portion in a circumferential direction, and the surface on the one axial side of the blade has a first convex surface and a second convex surface extending from a predetermined position in the circumferential direction of the hub in a direction away from the center axis.

The flow of air on the negative pressure surface (surface on the axial side of the vane) is disturbed by acceleration, but by providing an inflection point (between the first convex surface and the second convex surface), the flow of air can be suppressed from growing largely disturbed. Further, the distance between the rear end of the blade and the last convex surface (between the second convex surfaces) is short, and the flow of air can be prevented from growing largely in a turbulent manner. Further, since the air flow on the negative pressure surface side of the rear end portion of the blade is accelerated to the same extent as the air flow on the positive pressure surface side (the other surface in the axial direction of the blade) by the last convex surface (between the second convex surfaces), the disturbance of the merged flow can be suppressed.

The other axial surface of the blade is located on one axial side of the blade chord, and the distance between the other axial surface of the blade and the blade chord is farthest in the circumferential direction from the center toward the tip end of the blade.

The distance between the positive pressure surface of the blade and the blade chord is farthest from the blade tip in the circumferential direction at the midpoint, and there is no inflection point. Therefore, the air on the positive pressure surface side is gradually accelerated along the blade surface, and therefore turbulence of the flow can be suppressed.

In addition, the first convex surface is provided on the blade tip end portion side, and the second convex surface is provided on the blade trailing end portion side.

The distance between the suction surface of the blade and the blade chord is a convex surface (a first convex surface and a second convex surface) because the distance between the suction surface of the blade and the blade chord is greater on both sides of the inflection point than on the inflection point. Therefore, the air on the negative pressure surface side is accelerated at the first convex surface and flows along the trailing blade surface, and is accelerated again at the second convex surface with respect to the inflection point, whereby occurrence and growth of turbulence in the flow of the air can be suppressed.

In addition, the second convex surface extends continuously from the hub to a radially outer end of the blade.

The occurrence and growth of turbulence in the flow of air can be effectively suppressed in the entire radial direction of the blade.

In addition, an apex of the second convex surface as viewed in the circumferential direction extends in a direction away from the central axis at a constant interval from the blade rear end portion.

The occurrence and growth of disturbance in the flow of air can be effectively suppressed.

In addition, the apex of the second convex surface extends in a direction away from the central axis by a distance equal to the blade chord.

The flow of air on the negative pressure surface side flows along the second convex surface, and merges with the flow of air on the positive pressure surface side at the rear end of the blade. Since the heights of the second convexities are equal in the radial direction, the velocities of the flows of the air are also equal in the radial direction, so that setting of the heights becomes easy.

The impeller has a plurality of the blades, and the positions of the second convexities are different from each other among the plurality of the blades.

The impeller has a plurality of the blades, and the plurality of blades include the blade. The sizes of the second convex surfaces are different.

The PQ characteristic and the surge region vary depending on the attachment angle, shape, and rotation speed of the blade. However, the flow disturbance generated or grown in the surge region can be suppressed by the shape of the convex surface.

By making all of the plurality of blades have the same blade shape, it is possible to suppress a decrease in PQ characteristics due to surge at one rotation speed. On the other hand, when the engine is used at a plurality of rotation speeds, the optimum convex shape is different. By changing the convex shape for each of the plurality of blades, the suppression effect is reduced, but the reduction of the PQ characteristic can be suppressed at a wider rotation speed.

Further, since the turbulence of the air flow generated by each blade affects each other, the second convex surfaces 152 different from each other are provided on each blade surface, so that the turbulence of the air as a whole can be suppressed, and the reduction of the pressure (P) and the air volume (Q) characteristics can be suppressed.

Further, an axial fan is provided in which an intake-side fan having the impeller and an exhaust-side fan are arranged in series.

In particular, in the tandem axial flow fan, a rib is provided downstream of the blades of the suction side fan. The turbulence of the air flow is further increased by the ribs, which causes a decrease in PQ characteristics, noise, and vibration. By forming the blades of the suction side fan in the above-described shape, the flow of air can be suppressed from being greatly disturbed, and therefore, the disturbance of air at the ribs can be suppressed.

Further, an information processing apparatus is provided with the axial flow fan.

An information processing device having improved cooling effect by an axial fan with improved PQ characteristics can be provided.

While the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and various modifications and changes can be made within the scope of the present invention. These embodiments and modifications thereof are included in the scope and gist of the utility model, and are also included in the utility model described in the claims and equivalent ranges thereof.

Claims (10)

1. An impeller of an axial flow fan, which rotates around a central axis,

the impeller has a hub at a center portion thereof, and has blades extending radially outward from the hub and having blade leading end portions on a front side in a rotation direction and blade trailing end portions on a rear side in the rotation direction,

the blade tip portion is provided on one axial side of the blade rear end portion,

the other axial surface of the blade is a concave surface that is curved to one axial side with respect to a blade chord that connects the blade tip portion and the blade trailing end portion in the circumferential direction,

the axial side surface of the blade has a first convex surface and a second convex surface that extend in a direction away from the center axis from a predetermined position in the circumferential direction of the hub.

2. The impeller according to claim 1,

the surface of the other axial side of the blade is positioned closer to one axial side than the blade chord,

the distance between the surface on the other axial side of the blade and the blade chord is farthest on the side closer to the blade tip end than the midpoint in the circumferential direction.

3. The impeller according to claim 1 or 2,

the first convex surface is provided on the side of the blade tip portion, and the second convex surface is provided on the side of the blade trailing end portion.

4. The impeller according to claim 1 or 2,

the second convex surface extends continuously from the hub to a radially outer end of the blade.

5. The impeller according to claim 1 or 2,

an apex of the second convex surface as viewed in the circumferential direction extends in a direction away from the central axis at a constant interval from the blade trailing end portion.

6. The impeller according to claim 1 or 2,

the apex of the second convex surface extends in a direction away from the central axis at a distance equal to the blade chord.

7. The impeller according to claim 1 or 2,

the impeller has a plurality of said blades,

in the plurality of blades, the intervals of the second convex surfaces from the rear end parts of the blades are different.

8. The impeller according to claim 1 or 2,

the impeller has a plurality of said blades,

the second convex surfaces are spaced from the chord of the blade by different distances among the plurality of blades.

9. An axial-flow fan, characterized in that,

the axial flow fan is configured by connecting a suction side fan and an exhaust side fan in series, wherein the suction side fan is provided with an impeller according to any one of claims 1 to 8.

10. An information processing apparatus characterized in that,

the information processing apparatus has the axial flow fan according to claim 9.

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