JP7317235B2 - Multi-blade impeller and centrifugal blower - Google Patents

Description

The present disclosure relates to multi-blade impellers and centrifugal fans having multiple blades.

A multi-blade impeller has a structure in which an impeller with a plurality of blades arranged in a ring is rotated and the air sucked from the inner periphery of the impeller is blown out from between the blades in the centrifugal direction. Because this rotational motion exerts centrifugal force on the blades of a multi-blade impeller, generally an annular reinforcing ring that secures the blades is connected to the outer edge of the blades. Deformation of the wings can be suppressed by providing the reinforcing ring.

In addition, as disclosed in Patent Document 1, in order to obtain a large air volume by rotating the multi-blade impeller, the shape of the blades is forward-facing with respect to the direction of rotation, and the exit angle of the blades is greater than 90°. For example, there is a multi-blade impeller with a blade exit angle of 150 to 170°.

JP-A-6-74195

In blades with an exit angle greater than 90°, the angle of connection with the reinforcing ring becomes acute, resulting in places where stress tends to concentrate. Therefore, there is a problem that deformation of the wing cannot be sufficiently suppressed only by connecting the wing and the reinforcing ring.

The present disclosure has been made in view of the above, and an object thereof is to obtain a multi-blade impeller capable of suppressing blade deformation.

In order to solve the above-described problems and achieve the object, the present disclosure provides a main plate that rotates about a rotation axis and has a circular shape when viewed along the rotation axis, and a main plate that is spaced apart from each other along the outer peripheral edge of the main plate. It comprises a plurality of blades arranged at intervals and extending in the direction along the rotation axis, and an annular reinforcing ring provided at a position apart from the main plate in the direction along the rotation axis and surrounding the plurality of blades. The blades are provided with protruding portions that protrude in a direction that is different from the exit direction of the blades and toward the outside in the radial direction of the main plate on the outer edge portion that is the outer peripheral edge side, and the plurality of blades and reinforcement are provided via the protruding portions. connected to the ring. The cross-sectional area of the protruding portion, which is taken along the circumferential direction of the main plate, becomes smaller toward the outer side in the radial direction.

Advantageous Effects of Invention According to the present disclosure, it is possible to obtain a multi-blade impeller capable of suppressing blade deformation.

1 is a perspective view of a centrifugal fan according to Embodiment 1 1 is a perspective view of a multi-blade impeller according to Embodiment 1 A top view of the multi-blade impeller according to the first embodiment Partially enlarged view in which the K portion shown in FIG. 3 is enlarged Cross-sectional view along the VV line shown in FIG. Top view of a multi-blade impeller according to a comparative example Partially enlarged view in which the L portion shown in FIG. 6 is enlarged Partially enlarged view of the multi-blade impeller according to Modification 1 Partially enlarged view of a multi-blade impeller according to modification 2 Partially enlarged view of a multi-blade impeller according to modification 3 Sectional view along line XI-XI shown in FIG. FIG. 11 is a cross-sectional view of a multi-blade impeller according to Modification 4, corresponding to the cross-sectional view taken along line XI-XI shown in FIG. FIG. 10 is a cross-sectional view of a multi-blade impeller according to modification 5, corresponding to the cross-sectional view taken along line XI-XI shown in FIG. FIG. 4 is a cross-sectional view showing an example of the position of a reinforcing ring provided in the multi-blade impeller according to Embodiment 1; FIG. 11 is a cross-sectional view of a multi-blade impeller according to Modification 6, corresponding to the cross-sectional view taken along line XI-XI shown in FIG. Perspective view of a multi-blade impeller according to modification 6 FIG. 11 is a cross-sectional view of a multi-blade impeller according to modification 7, which corresponds to a cross-sectional view taken along line XI-XI shown in FIG. 10; FIG. 11 is a cross-sectional view of a multi-blade impeller according to modification 8, which corresponds to a cross-sectional view taken along line XI-XI shown in FIG. FIG. 11 is a cross-sectional view of a multi-blade impeller according to Modification 9, corresponding to the cross-sectional view taken along line XI-XI shown in FIG. FIG. 4 is a diagram comparing the maximum stress values applied to the multi-blade impeller according to the first embodiment and the multi-blade impeller according to the comparative example;

A multi-blade impeller and a centrifugal fan according to embodiments will be described in detail below with reference to the drawings.

Embodiment 1.
FIG. 1 is a perspective view of a centrifugal fan according to Embodiment 1. FIG. Centrifugal blower 7 includes scroll casing 8 , multi-blade impeller 1 , and drive motor 2 . The scroll casing 8 accommodates the multi-blade impeller 1 inside. The scroll casing 8 is formed with a suction port 10 for taking in air and a blowout port 9 for blowing out air from the inside. The drive motor 2 rotates the multi-blade impeller 1 inside the scroll casing 8 . In the centrifugal blower 7 , the air sucked from the suction port 10 is blown out from the blowout port 9 by rotating the multi-blade impeller 1 .

2 is a perspective view of the multi-blade impeller according to the first embodiment. FIG. 3 is a top view of the multi-blade impeller according to the first embodiment. FIG. A multi-blade impeller 1 is rotated around a rotary shaft 11 by a drive motor 2 . The multi-blade impeller 1 has a circular main plate 3 when viewed along the rotating shaft 11 . The multi-blade impeller 1 includes a plurality of blades 4 arranged at intervals along the outer peripheral edge of the main plate 3 and extending in the direction along the rotation axis 11 . The multi-blade impeller 1 includes an annular reinforcing ring 5 that is provided at a position apart from the main plate 3 in the direction along the rotating shaft 11 and surrounds the plurality of blades 4 .

FIG. 4 is a partial enlarged view enlarging the K portion shown in FIG. FIG. 5 is a cross-sectional view taken along line VV shown in FIG. An outer edge portion 4a of the blade 4 is provided with a projection 6 that projects radially outward of the main plate 3 in a direction different from the exit direction A determined by the exit angle α of the blade 4 . The plurality of blades 4 and the inner peripheral surface 5a of the reinforcing ring 5 are connected via the projections 6. As shown in FIG.

As the multi-blade impeller 1 is rotated by the drive motor 2 , a centrifugal force F acts on the outer peripheral portion of the multi-blade impeller 1 . Moreover, the centripetal force G acts on the blade 4 through the protrusion 6 because the protrusion 6 is provided in the direction facing the centrifugal force F. As shown in FIG. By connecting the blades 4 and the reinforcing ring 5 via the protrusions 6, the connection angle between the blades 4 and the reinforcing rings 5 is no longer an acute angle. Difficulty concentrating. Therefore, deformation of the blade 4 can be suppressed. Since the stress generated at the connection point between the blade 4 and the protruding portion 6 is difficult to concentrate, the blade 4 can be made thinner, or the blade 4 can be formed of a low-strength, inexpensive material, resulting in a multi-blade impeller. It is possible to suppress the manufacturing cost of 1.

Further, as shown in FIG. 5, a protrusion 6 protruding from the outer edge 4a of the blade 4 is provided between the outer edge 4a of the blade 4 and the inner peripheral surface 5a of the reinforcing ring 5, so that the rotating shaft When the reinforcing ring 5 is projected along the line 11, the main plate 3 is provided at a position away from the projection destination. Thereby, when manufacturing the multi-blade impeller 1 by injection molding, the mold can be pulled out in the direction along the rotating shaft 11 . Since the mold can be pulled out in the direction along the rotating shaft 11, there is no need to change the shape of the main plate 3 in consideration of the mold pull-out. Therefore, it is possible to simplify the shape of the mold and reduce the cost required for designing the mold, so that the manufacturing cost of the multi-blade impeller 1 can be reduced.

FIG. 6 is a top view of a multi-blade impeller according to a comparative example. FIG. 7 is a partially enlarged view showing an enlarged portion L shown in FIG. In the multi-blade impeller 101 according to the comparative example, the outer edges 4a of the blades 4 are directly connected to the reinforcing ring 105 . In the multi-blade impeller 101 according to the comparative example, the blades 4 and the reinforcing ring 5 are connected at an acute angle. Therefore, in some cases, the deformation of the blade 4 cannot be sufficiently suppressed. On the other hand, in the multi-blade impeller 1 according to the first embodiment, by connecting the blades 4 and the reinforcing ring 5 via the protrusions 6, the stress is less likely to concentrate, and the multi-blade impeller 1 deformation can be suppressed.

In addition, in the multi-blade impeller 101 according to the comparative example, the reinforcement ring 105 is directly connected to the outer edge portion 4 a of the blade 4 . end up Therefore, when manufacturing the multi-blade impeller 1 by injection molding, it is necessary to change the shape of the main plate 3 in order to remove the mold in the direction along the rotating shaft 11, which increases the manufacturing cost. On the other hand, in the multi-blade impeller 1 according to the first embodiment, since the mold can be removed in the direction along the rotating shaft 11, it is unnecessary to change the shape of the main plate 3, and the manufacturing cost is suppressed. can do.

8 is a partially enlarged view of a multi-blade impeller according to Modification 1. FIG. In the example shown in FIG. 4, since the multi-blade impeller 1 has a forward-facing blade shape with respect to the rotation direction, the curvature radii of the suction surface 4b of the blade 4 and the pressure surface 4c of the blade 4 differ depending on the thickness of the blade 4. , the angle of connection to the protruding portion 6 also differs between the suction surface 4b side of the blade 4 and the pressure surface 4c side of the blade 4 . Therefore, the magnitude of the stress generated at the joint between the blade 4 and the protruding portion 6 differs between the suction surface 4b side of the blade 4 and the pressure surface 4c side of the blade 4 .

Therefore, in the multi-blade impeller 1 according to Modification 1, as shown in FIG. provide variation in cross-sectional area, shape and angle of connection. As a result, the stress generated on the suction surface 4b of the blade 4 and the stress generated on the pressure surface 4c of the blade 4 can be reduced separately.

As the connection area of the protrusion 6 connected to the outer edge 4a of the blade 4 is larger, the stress generated at the connection point between the blade 4 and the protrusion 6 is reduced. On the other hand, as the weight of the protrusion 6 increases, the centrifugal force acting on the blade 4 also increases, so the stress generated at the connecting portion between the blade 4 and the protrusion 6 increases. Therefore, in the multi-blade impeller 1 according to Modification 1, the cross-sectional area of the projecting portion 6 is reduced by decreasing the width along the circumferential direction of the main plate 3 toward the radially outer side of the main plate 3. ing. As a result, it is possible to connect the projection 6 and the blade 4 while securing the connection area between the projection 6 and the blade 4 while suppressing the weight of the projection 6, so that the strength of the impeller can be expected to be improved more effectively.

FIG. 9 is a partially enlarged view of a multi-blade impeller according to Modification 2. FIG. As described above, the radius of curvature of the pressure surface 4c of the blade 4 is smaller than that of the suction surface 4b of the blade 4, so the connection angle with the protrusion 6 is acute. Therefore, the stress generated at the connection point between the pressure surface 4c of the blade 4 and the protrusion 6 is higher than the stress generated at the connection point between the suction surface 4b of the blade 4 and the protrusion 6. FIG. Therefore, in the multi-blade impeller 1 according to Modification 2, the side surface 6a of the protrusion 6 connected to the pressure surface 4c of the blade 4 overlaps with the radiation M from the rotation shaft 11 when viewed along the rotation shaft 11. there is A side surface 6a of the projecting portion 6 is a surface on the front side of the multi-blade impeller 1 in the rotation direction. Since the centripetal force G in the protrusion 6 becomes maximum toward the rotation axis 11, the side surface 6a is formed so as to overlap the radiation M from the rotation axis 11, thereby connecting the pressure surface 4c of the blade 4 and the protrusion 6. It is possible to further reduce the stress generated at the location.

10 is a partially enlarged view of a multi-blade impeller according to Modification 3. FIG. 11 is a cross-sectional view taken along line XI-XI shown in FIG. 10. FIG. FIG. 12 is a cross-sectional view of a multi-blade impeller according to Modification 4, corresponding to the cross-sectional view taken along line XI-XI shown in FIG. FIG. 13 is a cross-sectional view of a multi-blade impeller according to Modification 5, corresponding to the cross-sectional view taken along line XI-XI shown in FIG.

In the multi-blade impeller 1 according to Modification 3 to Modification 5, the reinforcement ring 5 is provided with a plurality of inner peripheral surfaces 5a1 and 5a2 facing radially inward, and at least one of the inner peripheral surfaces 5a1 and 5a2 is provided. is inclined with respect to the rotation axis 11 . As a result, the width of the reinforcing ring 5 in the direction along the rotating shaft 11 is increased from the radially inner end to the partway toward the radially outer side, and the cross-sectional area of the cross section cut along the circumferential direction is also expand.

Here, since bending stress acts on the connection points between the blades 4 and the protrusions 6 of the multi-blade impeller 1 and the connection points between the reinforcing ring 5 and the protrusions 6, the stress is greater on the surface than inside the substance. Become. In the multi-blade impeller 1 according to Modifications 3 to 5, the reinforcement ring 5 is provided with a plurality of inner peripheral surfaces 5a1 and 5a2, so that the cross-sectional shape and The connecting angle can be adjusted according to the plurality of inner peripheral surfaces 5a1 and 5a2. Therefore, compared to the case where the inner peripheral surface of the reinforcing ring 5 is formed by only one surface, the connection area of the protrusion 6 connected to the outer edge portion 4a of the blade 4 is maintained according to the generated stress, and the protrusion 6 The weight of 6 can be suppressed further. In addition, in the multi-blade impeller 1 according to Modification 3 shown in FIG. 10, the protruding portion 6 is small in the region where the stress inside the substance is small. In addition, the inner peripheral surface may be formed of three or more surfaces.

14 is a cross-sectional view showing an example of the position of a reinforcing ring included in the multi-blade impeller according to Embodiment 1. FIG. As shown in FIG. 14, when the multi-blade impeller 1 rotates, air flows from the radially inner side to the radially outer side in the reinforcing ring 5 . In the multi-blade impeller 1 according to Modifications 3 to 5, since the width of the reinforcement ring 5 in the direction along the rotation axis 11 increases from the radially inner end toward the radially inner side, the diameter It is possible to smoothly pass the air flowing from the inner side to the outer side in the radial direction. As a result, it is possible to reduce noise and improve air blowing performance.

In addition, as shown in FIG. 14, inertial force is generated in the air flowing through the multi-blade impeller 1, resulting in a velocity distribution biased toward the main plate 3 side. Therefore, as shown in FIG. 14, when the reinforcement ring 5 is provided in the middle of the outer edge portion 4a of the blade 4 of the multi-blade impeller 1 in the direction along the rotation axis 11, the reinforcement ring 5 has a plurality of inner circumferences. By providing the surfaces 5a1 and 5a2 and increasing the width in the direction along the rotating shaft 11 from the radially inner end toward the radially inner side, the effect of smoothing the air flow is enhanced.

The inner peripheral surface 5a may be uneven or curved so that the air blown out from between the blades 4 of the multi-blade impeller 1 can easily flow around the reinforcing ring 5. FIG.

FIG. 15 is a cross-sectional view of a multi-blade impeller according to Modification 6, corresponding to the cross-sectional view taken along line XI-XI shown in FIG. 16 is a perspective view of a multi-blade impeller according to Modification 6. FIG. In the multi-blade impeller 1 according to Modification 6, part of the reinforcing ring 5 is directly connected to the outer edge portion 4a of the blade 4 . Specifically, the width along the radial direction is defined by the lower surface 5b of the reinforcing ring 5 facing the main plate 3 side and the upper surface 5c of the reinforcing ring 5 facing the side opposite to the main plate 3 side. making it different. In the multi-blade impeller 1 according to Modification 6, the width along the radial direction of the lower surface 5b is wider than the width along the radial direction of the upper surface 5c. In addition, since the lower surface 5b protrudes radially inward from the upper surface 5c, the region of the inner peripheral surface of the reinforcing ring 5 closer to the main plate 3 is directly connected to the outer edge portion 4a of the blade 4. As shown in FIG. As a result, although the connection area between the projecting portion 6 and the blade 4 is reduced and the effect of improving the strength of the impeller is reduced, the reinforcing ring 5 can be easily formed integrally, so that the manufacturing cost can be suppressed.

17 is a cross-sectional view of a multi-blade impeller according to Modification 7, corresponding to the cross-sectional view taken along line XI-XI shown in FIG. In the multi-blade impeller 1 according to Modification 7, contrary to the example shown in Modification 6, the width along the radial direction of the upper surface 5c is wider than the width along the radial direction of the lower surface 5b. Further, the upper surface 5 c protrudes radially inward from the lower surface 5 b , so that the region of the inner peripheral surface of the reinforcing ring 5 that is closer to the main plate 3 is directly connected to the outer edge portion 4 a of the blade 4 .

FIG. 18 is a cross-sectional view of a multi-blade impeller according to Modification 8, corresponding to the cross-sectional view taken along line XI-XI shown in FIG. FIG. 19 is a cross-sectional view of a multi-blade impeller according to Modification 9, corresponding to the cross-sectional view taken along line XI-XI shown in FIG.

In the multi-blade impeller 1 according to Modification 8 and Modification 9, while the projecting portion 6 is connected to the inner peripheral surface 5a of the reinforcing ring 5, the lower surface 5b side of the reinforcing ring 5 facing the main plate 3 side has The strength of the multi-blade impeller 1 is improved by extending or connecting the same.

FIG. 20 is a diagram comparing maximum stress values applied to the multi-blade impeller according to the first embodiment and the multi-blade impeller according to the comparative example. Maximum stress values are calculated from structural analysis. As shown in FIG. 20, compared with the multi-blade impeller 101 according to the comparative example, the multi-blade impeller 1 according to the modified example 2 shown in FIG. The multi-blade impeller 1 reduces the maximum stress value by about 14%.

The multi-blade impeller exemplified in the first embodiment can be applied not only to a single-suction centrifugal fan but also to a double-suction centrifugal fan. Moreover, it can be applied not only to blowers for air conditioning and ventilation, but also to other equipment. Further, the shape of the projecting portion 6 and the shape of the reinforcing ring 5 shown in each modified example may be combined.

The configuration shown in the above embodiment is an example, and can be combined with another known technique, or can be combined with other modifications without departing from the scope of the invention. , it is also possible to omit or change part of the configuration.

Reference Signs List 1, 101 multi-blade impeller, 2 drive motor, 3 main plate, 4 blades, 4a outer edge, 5, 105 reinforcement ring, 5a, 5a1, 5a2 inner peripheral surface, 5b lower surface, 6 protrusion, 7 centrifugal blower, 8 scroll Casing, 9 blower port, 10 suction port, 11 rotating shaft.

Claims (5)

a main plate that rotates about a rotation axis and has a circular shape when viewed along the rotation axis;
a plurality of blades arranged at intervals along the outer peripheral edge of the main plate and extending in a direction along the rotation axis;
an annular reinforcing ring provided at a position away from the main plate in the direction along the rotation axis and surrounding the plurality of blades;
The blade is provided with a projecting portion projecting in a direction different from the exit direction of the blade and toward the outside in the radial direction of the main plate on the outer edge portion that is the outer peripheral edge side,
The protruding portion has a cross-sectional area of a cross section cut along the circumferential direction of the main plate that decreases toward the outer side in the radial direction,
A multi-blade impeller, wherein the plurality of blades and the reinforcing ring are connected via the protrusions. 2. The multi-blade impeller according to claim 1, wherein the protruding portion has a surface on the front side in the rotation direction of the main plate that overlaps with the radiation from the rotating shaft when viewed along the rotating shaft. 3. The reinforcing ring has a large cross-sectional area taken along a plane along the circumferential direction of the main plate from the radially inner end portion to a partway toward the radially outer side. 3. The multi-blade impeller according to 1 or 2. 4. The multi-blade impeller according to any one of claims 1 to 3, wherein a part of the inner peripheral surface of the reinforcing ring is connected to the outer peripheral edges of the blades. A multi-blade impeller according to any one of claims 1 to 4;
A centrifugal fan comprising: a scroll casing housing the multi-blade impeller.

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