WO2022137431A1

WO2022137431A1 - Centrifugal fan and rotating electric machine using centrifugal fan

Info

Publication number: WO2022137431A1
Application number: PCT/JP2020/048451
Authority: WO
Inventors: 惠介武石; 眞一郎南; 真吾井上
Original assignee: 三菱電機株式会社
Priority date: 2020-12-24
Filing date: 2020-12-24
Publication date: 2022-06-30
Also published as: JPWO2022137431A1; JP7123283B1

Abstract

This centrifugal fan is characterized by comprising: a disc-shaped main plate (2) provided around a rotary shaft; and a plurality of blades (4) which are formed around the main plate and extend in an axial direction of the rotary shaft and of which the front-end side and the rear-end side in the rotational direction are respectively provided on the inside and outside in the radial direction, wherein the blade has a front-end side apex part (C) on the front-end side having the highest axial height and a rear-end side apex part (D) on the rear-end side, and at least one of the plurality of blades has a different radial length, from the front-end side apex part to the rear-end side apex part, than the other blades.

Description

Centrifugal fan and rotary electric machine using centrifugal fan

The present application relates to a centrifugal fan and a rotary electric machine using a centrifugal fan.

Conventionally, as a so-called centrifugal fan, for example, there is one disclosed in the prior art document 1, and it is used for the purpose of transporting a gas such as air or a liquid such as a refrigerant. The centrifugal fan includes a plurality of blades arranged in the circumferential direction, and a disk-shaped or bowl-shaped hub at one end in the axial direction of the blades. There are also centrifugal fans with an annular shroud at the end opposite the hub of the blade.
For example, Patent Document 1 shows a centrifugal fan having an annular shroud and a bowl-shaped hub. The connection point between the bowl-shaped hub and the blade is a smooth concave curve, and the connection line is tangent to the connection line. By inclining toward the center of rotation, it is possible to improve the efficiency and noise of the centrifugal fan.
Further, in Patent Document 2, in such a centrifugal fan, the air volume performance is improved and the noise is reduced by changing the shape of each blade or the distance between the blades.

Japanese Unexamined Patent Publication No. 2004-353608 Heisei 4-183244 Gazette

In the centrifugal fan of the conventional structure, the wind noise generated from the centrifugal fan increases as the rotation speed increases, which causes a problem of causing discomfort. Further, when the discrete frequency generated from the centrifugal fan (when the rotation speed is n and the number of blades is z, it is also called nz noise at the frequency of n × z), it is modulated in the frequency band around the number of blades z. , A component having a large noise value modulated in the frequency band of z + 1, z + 2, ... Which is larger than the number of blades z is generated, which causes a problem of causing discomfort. In particular, in an in-vehicle rotary electric machine, if the air volume is increased in order to cool a component at a low rotation speed, there is a problem that the unpleasant feeling of wind noise increases at a high rotation speed.

In the conventional structure as disclosed in Patent Document 1, it is possible to suppress the peeling generated on the negative pressure surface of the blade at a specific rotation speed centering on a low rotation speed and reduce the wind noise generated from the centrifugal fan. However, the centrifugal fan having a conventional structure has a problem that when it is operated in a wide rotation range from a low rotation range to a high rotation range, wind noise increases especially in a high rotation range, which causes a great discomfort. In particular, since the rotary electric machine has a wide operating range from the low rotation range to the high rotation range, wind noise is often generated remarkably in the high rotation range, and mechanical friction noise, electromagnetic noise and engine in the low rotation range. Since it is masked by the sound, the wind noise in the low rotation range is inconspicuous, and there is a problem that the wind noise in the high rotation range is large and the discomfort is great.
Further, in the conventional structure as disclosed in Patent Document 2, noise is reduced by changing the pitch, but there is a problem that it is not effective in reducing wind noise at high rotation speed.

The present application is to solve such a conventional problem, and has a simple structure that does not cause an increase in cost, and reduces wind noise (overall value) generated from a centrifugal fan in a specific rotation speed region where the rotation speed is high. The purpose is to make it possible.

The centrifugal fan according to the present application is formed around a disk-shaped main plate provided around the rotation axis and the main plate, extends in the axial direction of the rotation axis, and has a radial tip side in the rotation direction. It is provided with a plurality of blades provided on the inside with the rear end side on the outer side in the radial direction, and the blades have an apex portion on the tip side on the tip side where the height in the axial direction is the highest, and a rear blade on the rear end side. It has an end-side apex portion, and at least one of the plurality of blades is formed so that the radial length from the front end-side apex portion to the rear end-side apex portion is different from other blades. Is.

By making the length in the radial direction from at least one of the plurality of blades from the apex on the distal end side to the apex on the rear end side different from the length of the other blades, the length on the negative pressure surface of the blade is set. Peeling is more likely to occur at higher rotation speeds, and the flow rate in a specific rotation speed region can be reduced, and wind noise can be reduced while ensuring the flow rate required for cooling.
By doing so, it is possible to reduce the wind noise (overall value) generated from the centrifugal fan in a specific rotation speed region where the rotation speed is high with a simple structure.

It is a perspective view which shows the centrifugal fan which concerns on Embodiment 1. FIG. It is a schematic diagram which shows the blade of the centrifugal fan which concerns on Embodiment 1. FIG. It is a schematic diagram which shows the blade of the centrifugal fan which concerns on Embodiment 1. FIG. It is a figure which shows the comparison with the conventional product of the centrifugal fan which concerns on Embodiment 1. FIG. It is a schematic diagram which shows the blade of the centrifugal fan which concerns on Embodiment 2. It is a schematic diagram which shows the blade of the centrifugal fan which concerns on Embodiment 4. It is a schematic diagram which shows the blade of the centrifugal fan which concerns on Embodiment 5. It is sectional drawing which shows the rotary electric machine which concerns on Embodiment 7. It is a front view which shows the casing of the rotary electric machine which concerns on Embodiment 7. It is a schematic diagram which shows the centrifugal fan of the rotary electric machine which concerns on Embodiment 7. It is a schematic diagram which shows the casing of the rotary electric machine and the centrifugal fan which concerns on Embodiment 8. It is a figure which shows the relationship between the overlap of the casing of the rotary electric machine and the blade, the flow rate and the wind noise which concerns on Embodiment 8.

Embodiment 1.
The centrifugal fan according to the first embodiment of the present application is shown in FIG. The centrifugal fan 1 is attached to a rotating object, a rotor of a rotary electric machine, or the like, and has a disk-shaped main plate 2 around the rotating shaft, a plurality of arm-shaped plates 3 extending from the main plate 2, and a plurality of extending in the axial direction. It is equipped with a blade 4 of the above. As shown in FIG. 2, the blade 4 is provided with the front end side in the rotation direction on the inside in the radial direction and the rear end side on the outside in the radial direction.

In the future description, the direction parallel to the axis of rotation center R, which is the center of the rotation axis, is the axial direction, the direction in which the blade 4 extends from the flow of fluid is the suction side, and the opposite side is the main plate. Called the 2nd side. Further, the length of the suction side in the axial direction from the main plate 2 may be expressed as a height. Further, the direction extending in the circumference perpendicular to the axial direction is called the circumferential direction. Further, the direction from the center of rotation to the outside is the radial direction, the side facing the center of rotation is expressed as the radial inner side or the inner peripheral side, and the opposite side is expressed as the radial outer side or the outer peripheral side.

The main plate 2 may have a substantially plate-like shape (for example, a disk) or a plate having protrusions such as ribs, and as shown in FIG. 1, for passing a shaft for rotation in the center of the plate. The shape may be provided with a hole, further may be a shape in which the center of rotation bulges like a bowl, and there may be a notch between the wings. The arm-shaped plate 3 is a shape portion extending radially outward from a part of the outer circumference of the ring shape, and is flush with the outer circumference of the main plate 2. The arm-shaped plate 3 is provided with ribs for strengthening strength and the like. May be. There may be an outer peripheral portion of the main plate 2 between the two adjacent arm-shaped plates 3, or they may be connected between the adjacent arm-shaped plates 3 so that there is no outer peripheral portion of the main plate 2. A rotation center R exists near the center of the ring-shaped portion of the main plate 2, and a rotation axis is provided so as to pass through the rotation center R and be orthogonal to the main surface of the main plate 2. The blade 4 has a shape that rises at a substantially right angle from the outer peripheral side of the arm-shaped plate 3, and is therefore a portion that is approximately parallel to the axis of rotation. The method of raising the blade 4 does not have to be perpendicular to the main plate 2, and may be set so as to have a constant angle with the main plate 2. The main plate 2 or the arm-shaped plate 3 extending from the main plate 2 may be provided with a cooling hole 5, and the shape of the cooling hole 5 may be a circular shape, an elliptical shape, a substantially polygonal shape, or a plurality of cooling holes 5. It may be provided. Further, when a plurality of cooling holes 5 are provided, the shape of each cooling hole 5 may be different. Further, in the cooling holes 5 provided in the main plate 2 and the arm-shaped plate 3 extending from the main plate, a round is formed at the end of the cooling holes 5 on the blade 4 side so as to reduce the ventilation resistance of the flow sucked into the rotor. Alternatively, chamfering may be provided.

With such a configuration, when the main plate 2 rotates, a wind is generated so as to be discharged radially outward along the blade 4, and the air flowing into the central portion of the main plate 2 is discharged to the outer peripheral side. It is a centrifugal fan. The radial outside of the blade 4 is a positive pressure surface that discharges airflow, and the radial inside of the blade 4 is a negative pressure surface. Further, the height of the blade 4 in the axial direction is low at the leading edge in the rotation direction and high at the trailing edge so that the collision of wind at the leading edge is reduced. Further, an annular shroud may be provided at the end of the blade 4 opposite to the main plate 2.
The blade 4 does not have to be a flat surface. For example, FIG. 1 shows an example of a smoothly connected curved surface in which the inner peripheral side looks concave and the outer peripheral side looks convex when viewed from the outside. May be. The blade 4 may have a shape in which a part or all of the blade 4 is inclined at an appropriate angle with respect to the rotation axis, and when viewed from the axial direction, the shape of the blade 4 may be linear, arcuate, or S-shaped. It may be in the form. Further, the blades 4 may be at equal intervals or unequal intervals in the rotation direction, and the blade shapes of the blades 4 may be the same or a plurality of blade shapes may be combined. When the intervals are unequal, the positions of the arm-shaped plates 3 are also unevenly spaced in the rotation direction, and the ring-shaped portion of the main plate 2 is not exposed between the two arm-shaped plates 3 that are close to each other, that is, The base portion of the two arm-shaped plates 3 connected to the main plate 2 may be partially connected. Since the blade 4 has a shape that is bent from the outer circumference of the arm-shaped plate 3 extending in the radial direction and rises in the axial direction, it can be easily formed by bending a continuous plate, but it is not always formed at the end. May be.

[Correction under Rule 91 14.06.2021]
The cooling holes 5 may be provided in all the arm-shaped plates 3, but only one may be provided. Not only the cooling hole 5, but also a part of the arm-shaped plate 3 in the radial direction may be thinned in order to increase the air flow flowing in the axial direction. For example, if the arm-shaped plate 3 having no cooling hole 5 is provided with a notch in the radial leading edge or trailing edge, the air flow flowing in the axial direction can be increased. It is desirable that the centrifugal fan 1 be installed so that air can easily flow through the cooling hole 5 in the direction opposite to the direction in which the blade 4 is bent. The air that has passed through the cooling hole 5 escapes in the rotation axis direction of the centrifugal fan, and a part of the air flows in the centrifugal direction as the main plate 2 rotates. Further, the weight can be reduced by providing the cooling hole 5 in the main plate 2 or the arm-shaped plate 3. Further, as described above, by providing a large number of cooling holes 5 in places where the installation density of the arm-shaped plate 3 is high, the center of gravity of the centrifugal fan 1 can be brought closer to the center of rotation, which has the effect of correcting the imbalance.
As shown in FIG. 2, the tip portion of the blade 4 in the axial direction is A, the rear end portion is B, the tip end side apex having the highest axial height is C, and the rear end side apex is D. When the difference between the lengths of the line segments RD and RC when viewed from the axial direction as the center of rotation R is the radial length RD-RC from the apex on the front end to the apex on the rear end, a plurality of blades At least one of the four blades may have a radial length RD-RC from the apex portion on the distal end side to the apex portion on the rear end side different from that of the other blades. FIG. 3 shows a view of FIG. 2 from the axial direction. As described above, the blade is provided with a blade having a notch 4a parallel to the main plate 2 including an error between the apex D on the rear end side and the rear end portion B which is the wing tip on the rear end side. Therefore, the wind noise generated from the centrifugal fan 1 can be reduced. FIG. 4 shows a diagram comparing with the centrifugal fan 1 having a conventional shape. A reduction in wind noise can be seen in the high rpm range where the rpm is high.

In particular, when the rotation speed of the centrifugal fan 1 is high, in the blade 4 provided with the notch portion 4a, when the flow sucked from the suction side in the axial direction changes the direction of the flow in the centrifugal direction, the flow direction on the suction side is changed. This is because the length of the apex is short, and the higher the rotation speed, the easier it is to peel off on the negative pressure surface, which greatly reduces the flow rate and enhances the effect of reducing wind noise. The effect of such peeling does not cause a shortage of air volume in the entire centrifugal fan 1, but can reduce the flow rate in a specific rotation speed region, and wind noise while ensuring the flow rate required for cooling. Can be reduced. Further, since the centrifugal force applied to the blade can be reduced by the notch portion 4a provided in the blade 4, the strength is also excellent.

Further, as shown in FIG. 3, the radial length RD-RC from the apex portion on the distal end side to the apex portion on the rear end side is a part of the blade shape of the blade 4 different from the other blades, and the tip side in the rotation direction E. It has a shape in which a concave surface 4b distorted radially outward from the rear end side and a convex surface 4c distorted radially inward from the rear end side are smoothly connected without a step. By forming the shape of the blade 4 in this way, it is possible to prevent peeling on the negative pressure surface in the low speed region, and while reducing wind noise in the low speed region, in the peeling region which is the high rotation speed region. The wind noise can be reduced.
In FIG. 3, the concave surface 4b and the convex surface 4c of the blade are expressed so as to be connected at one inflection point, but the linear portion may be sandwiched and smoothly connected without a step.

Embodiment 2.
In the first embodiment, the notch portion 4a is set in the outer peripheral portion on the suction side, but as shown in FIG. 5, in at least one blade shape, the suction side outside the rear end portion outer diameter RB on the main plate 2 side. By setting the shape of the blade 4 so that the diameter RD becomes smaller, it is possible to enhance the wind noise reduction effect as compared with the first embodiment. Further, by making the height in the axial direction monotonously small from the apex D on the rear end side of the blade 4 toward the outer rear end B in the radial direction, peeling on the negative pressure surface is efficiently controlled. It is possible to enhance the wind noise reduction effect in a continuous rotation speed region.

Embodiment 3.
As shown in FIG. 3, when the centrifugal fan is viewed from the suction side in the rotation axis direction, the angle between the front edge of the blades adjacent to each other in the circumferential direction and the rotation center is θ, and the blade on the front side in the rotation direction where θ is the maximum. The blade shape may be set so as to have a notch shape on the suction side. By making the radial length RD-RC from the apex on the front end side to the apex on the rear end side different from that of the other blades 4, peeling of the blades in a specific rotation speed region is promoted and the air volume is suppressed. However, it was shown in the first embodiment that the effect of reducing wind noise is enhanced. By increasing the distance from the rear blades in this way, it is possible to prevent reattachment to the blades behind the peeling that occurred in the high rotation range, and it is possible to suppress an increase in wind noise due to reattachment.

Embodiment 4.
As shown in FIG. 6, for the blades 4 provided on the centrifugal fan 1, the tip portions A of the blades are set to A1, A2, ..., Ai, ..., An in the counter-rotation direction in each blade. Further, the angle connecting the tip Ai of the i-th blade, the rotation center R, and the tip A (i + 1) of the blades adjacent to each other in the counter-rotation direction is set as θi, and θ1 is maximized in θi. The numbers of the tip A of the blade 4 are set as A1, A2, ... In order. Similarly, the apex portion C on the tip end side of the blade 4 is defined as C1, C2, ... At this time, the length RC1 of the blade on the front side in the rotation direction of the blade where θ1 is maximum, that is, the blade of A1 from the rotation center R to the tip end side apex portion C1 of the blade 4, is RC1 <RCi (i = 2 to n). Therefore, RC1 may be set to be smaller than that of other blades. Further, the blade set so that RC1 is smaller than the other blades is set as the blade 4 having a radial length RD-RC from the apex portion on the front end side to the apex portion on the rear end side different from that of the other blades. Is also good. By doing so, it is possible to prevent reattachment to the blades behind the peeling that occurs in the high rotation range, and it is possible to suppress an increase in wind noise due to reattachment.

Embodiment 5.
In the fourth embodiment, RC1 is set only for the blade on the front side in the rotation direction of the blade having the maximum θ1, that is, the blade of A1, but the rotation of the blade in which θm is larger than the average value of θi (i = 1 to n). It may be set to have at least one blade on the front side in the direction, that is, a blade having RCm <RCi (i = 1 to n, where i ≠ m) for Am. FIG. 7 shows an example when m = 4. Further, the blade set so that RCm is smaller than the other blades is set as the blade 4 having a radial length RD-RC from the apex portion on the front end side to the apex portion on the rear end side different from that of the other blades. Is also good. By doing so, it is possible to prevent reattachment to the blades behind the peeling that occurs in the high rotation range, and it is possible to change the rotation speed that is effective in reducing wind noise, and a wide range of rotations can be performed. Noise reduction effect is expected in several bands.

Embodiment 6.
In the fourth embodiment, RC1 is set only for the blades on the front side in the rotation direction of the blades having the maximum θ1, that is, the blades on the A1 side. RCi may be set to be smaller than other blades that have not been set. Further, the blade set so that RCi is smaller than the other blades is set as the blade 4 having a radial length RD-RC from the apex portion on the front end side to the apex portion on the rear end side different from that of the other blades. Is also good. By doing so, it is possible to prevent reattachment to the blades behind the peeling that occurs in the high rotation speed range, and the rotation speed range where wind noise reduction occurs changes for each set blade and has a wide rotation speed. It is possible to obtain the effect of reducing wind noise in the region.

Embodiment 7.
The centrifugal fan 1 shown in the first to sixth embodiments may be attached to a rotor of a rotary electric machine such as an in-vehicle alternator, a motor, and an in-vehicle drive device for use. Here, as an example, an alternator for a vehicle to which the present application is applied is shown. FIG. 8 shows a rotary electric machine 100 to which the centrifugal fan 1 of the present application is applied. The rotary electric machine 100 has a casing 32 composed of a substantially bowl-shaped aluminum front side housing 31 and a rear side housing 30, and a pair of the casing 32. The shaft 34 rotatably supported via the bearing 33 of the above, the pulley 7 fixed to the end of the shaft 34 extending to the front side of the casing 32, and the pulley 7 rotating integrally with the shaft 34 into the casing 32. It includes a rotor 8 arranged and a stator 9 arranged facing the outer periphery of the rotor 8 and fixed to a casing 32.

Further, the rotary electric machine 100 is fixed to the extending portion of the shaft 34 extending to the rear side of the casing 32, and is slid on the surface of each slip ring 10 and a pair of one slip ring 10 for supplying an electric current to the rotor 8. A pair of moving brushes 11, a brush holder 17 accommodating these brushes 11, and a voltage regulator 12 adjacent to these brushes 11 to adjust the magnitude of the AC voltage generated in the stator 9. A rectifier 13 that rectifies the AC voltage generated by the stator 9 to a DC voltage, a heat sink 18, a connector 20 that inputs and outputs signals between the voltage regulator 12 and an external device (not shown), and a brush holder 17. A protective cover 27 is provided so as to cover the rectifying device 13.

The rotor 8 is a Randell type rotor in which an insulated copper wire is wound in a cylindrical and concentric manner, and a field winding 81 through which an exciting current flows to generate a magnetic flux and a magnetic flux generated by the generated magnetic flux cause magnetic poles. A field iron core 82 formed and provided so as to cover the field winding 81, each having 6, 8, or 10 or more and multiples of 2 claws, and an axial direction. A centrifugal fan having the characteristics of the above-described first to sixth embodiments, which is attached to both end surfaces by welding or the like to suck outside air into the generator by the rotation of the rotor 8 to cool and discharge the components in the generator. It is equipped with 1. The rotor 8 is formed by a field winding 81 and a field iron core 82, and is provided with a ventilation path for cooling the field windings. The rotor 8 and the centrifugal fan 1 provide an axial fluid. The field winding 81 is cooled by flowing.

The cooling performance may be improved by equipping the rotor 8 with a centrifugal fan 1 having the characteristics of the above-described first to sixth embodiments. FIG. 9 is a front view of the front side housing 31 which is the casing 32 of the rotary electric machine 100. An opening 32a serving as a suction port is provided on the suction side of the centrifugal fan 1 of the casing 32, and a discharge port 32b is provided on the sweep side. A plurality of openings 32a (four in FIG. 9) of the centrifugal fan 1 are provided, and the total outer shape of the openings 32a is the intake portion outer diameter 32r. FIG. 10 shows a view of the centrifugal fan 1 attached to the rotary electric machine 100 as seen from the suction side in the rotation axis direction. By setting the value to be large, not only can the wind noise be effectively reduced in the high rotation speed range, but also the decrease in the flow rate of the centrifugal fan can be prevented.

Further, by setting the suction side outer diameter RD of the blade 4 to be larger than the intake portion outer diameter 32r of the casing 32, not only the wind noise can be effectively reduced in the high rotation range, but also the centrifugal fan It is possible to prevent a decrease in flow rate. Furthermore, by arranging the blades so that the radial length RB from the center of rotation of the blades to the end on the rear end side differs between the blades adjacent to each other in the rotation direction, the position of the noise source on the casing is dispersed in the radial direction. It is possible to effectively reduce wind noise, and it is possible to prevent a decrease in flow rate and an increase in wind noise even in the high rpm range.

Embodiment 8.
FIG. 11 is an enlarged view of the area 40 surrounded by the dotted line in FIG. 8, and is shown as a schematic cross-sectional view showing a cross section in the F direction of FIG. In FIG. 11, the air passage shape is such that the flow 41 of the cooling air passes through the blades 4 of the centrifugal fan 1 and then expands in the axial direction. Parts such as the bearing 33, the pulley 7, and the rotor 8 are omitted.

A flat surface portion 32c substantially perpendicular to the axis of rotation on the fan facing surface of the casing 32, the radial length of the flat surface portion 32c is S, and the distal end side apex portion C and the rear end side apex portion D of the vane 4 of the centrifugal fan 1 form. Let T be the length in the axial direction between the apex portion and the plane portion 32c facing the apex portion. Further, the radial overlap length of the flat surface portion 32c facing the apex portion formed by the apex portion C on the front end side and the apex portion D on the rear end side of the blade 4 is set to Sa, and Sa is set to 1.5 T or more. Is also good. By setting in this way, it is possible to reduce the wind noise without reducing the flow rate of the centrifugal fan. FIG. 12 shows the relationship between the overlapping length Sa and the increase / decrease in the flow rate and the increase / decrease in the wind noise by a polygonal line.
Since the diameter of the vortex generated between the blade 4 of the centrifugal fan 1 and the casing 32 is about T, if the overlapping length Sa is 1 T or less, the vortex causes a large leakage from the positive pressure surface to the negative pressure surface of the blade, and the flow rate increases. The wind noise is increased because the airflow is turbulent due to the vortex. On the other hand, when the overlapping length Sa is larger than 1T, the flow leaking from the positive pressure surface to the negative pressure surface of the blade 4 can be suppressed and the generation of vortices can be suppressed, so that the wind noise can be reduced without reducing the flow rate. Is possible.

In particular, when the maximum axial length of the blade 4 with the flat surface portion 32c on the outer diameter side of the suction side outer diameter RD is U, U is set to 1.5 times or less of T. By making it a feature, it is possible to effectively suppress the generation of vortices in the outer diameter portion, which is effective in reducing wind noise. In FIG. 11, the shape of the casing 32 is shown so that the air passage after passing through the blade 4 expands in the axial direction, but the shape of the casing 32 may be such that the distance of T does not change, and T is The shape of the casing 32 may be reduced.

Embodiment 9.
In the above-described seventh embodiment, the outer diameter RB of the rear end portion of the blade is set to be larger than the outer diameter 32r of the intake portion for intake of the casing 32, but the outer diameter 32r of the intake portion of the casing 32 is set in the circumferential direction. It may be set to change. By setting in this way, the suction flow to the centrifugal fan becomes different in the circumferential direction, and the frequency of the discrete frequency sound generated by the blades of the centrifugal fan can be dispersed, so that the sound is effectively audible and jarring. Can be reduced.

Embodiment 10.
The above-mentioned embodiment 1. Then, a notch 4a is set in the outer peripheral portion on the suction side, but when the flat surface portion 32c of the casing has a donut shape when viewed from the direction of the rotation axis, the central axis of the flat surface portion 32c and the rotation center R of the centrifugal fan 1 And may be set to be displaced within T. By doing so, even if the blades have the same blade shape, the flat surface portion 32c facing the apex portion formed by the distal end side apex portion C and the rear end side apex portion D of the blade 4 overlaps in the radial direction. Since the length Sa can be changed at the circumferential position and the frequency of the discrete frequency sound generated by the blades of the centrifugal fan can be dispersed, it is possible to effectively reduce the audibly jarring sound. can.

Embodiment 11.
Regarding the centrifugal fan 1 described in the above-described embodiments 1 to 6, the distal end side apex portion C and the rear end side apex portion D of each blade 4 of the centrifugal fan 1 are set to be at different positions in the radial direction. May be good. By doing so, the radial overlap length Sa of the flat surface portion 32c facing the apex portion formed by the distal end side apex portion C and the rear end side apex portion D of the blade 4 can be changed at the circumferential position. This makes it possible to disperse the frequency of the discrete frequency sound generated by the blades of the centrifugal fan, so that it is possible to effectively reduce the audible and jarring sound.

Although the present application describes various exemplary embodiments and examples, the various features, embodiments, and functions described in one or more embodiments are applications of a particular embodiment. It is not limited to, but can be applied to embodiments alone or in various combinations. Therefore, innumerable variations not exemplified are envisioned within the scope of the techniques disclosed herein. For example, it is assumed that at least one component is modified, added or omitted, and further, at least one component is extracted and combined with the components of other embodiments.

1 Centrifugal fan, 2 Main plate, 3 Arm-shaped plate, 4 Blades, 4a Notch, 4b Concave surface, 4c Convex surface, 5 Cooling hole, 7 Pulley, 8 Rotor, 81 Field winding, 82 Field iron core, 9 Rotor, 10 slip ring, 11 brush, 12 voltage regulator, 13 rectifier, 17 brush holder, 18 heat sink, 20 connector, 27 protective cover, 30 rear side housing, 31 front side housing, 32 casing, 32a opening, 32b discharge port, 32c flat part, 32r intake part outer diameter, 33 bearing, 34 shaft, 40 area, 41 flow, 100 rotary electric machine, A tip part, B rear end part, C tip side apex part, D rear end side apex Part, E rotation direction, R rotation center, Sa overlapping length.

Claims

A disk-shaped main plate provided around the rotating shaft,
It is formed around the main plate, extends in the axial direction of the rotation axis, and at the same time.
It is provided with a plurality of blades provided with the tip side in the rotation direction on the inside in the radial direction and the rear end side on the outside in the radial direction.
The blade has an apex on the tip side on the tip side where the height in the axial direction is the highest, and an apex on the rear end side on the rear end side.
At least one of the plurality of blades is a centrifugal fan characterized in that the length in the radial direction from the apex portion on the front end side to the apex portion on the rear end side is different from that of other blades.
The side surface of the blade whose radial length from the apex on the tip side to the apex on the rear end side is different from that of other blades is a concave surface distorted radially outward from the tip side and a diameter from the rear end side. The centrifugal fan according to claim 1, wherein the convex surface distorted inward in the direction is formed by a surface smoothly connected to the convex surface.
The radial lengths of the apex portion on the tip end side and the apex portion on the rear end side are different from those of other blades. The centrifugal fan according to claim 1 or 2, wherein the centrifugal fan has a notch substantially parallel to the main plate between the rear end portion.
The length in the radial direction from the apex on the tip side to the apex on the rear end side is different from that of other blades. The centrifugal fan according to claim 1 or 2, wherein the fan is characterized by the above.
The blade having a radial length different from that of the other blades from the tip end side apex portion to the rear end side apex portion is the tip portion of each of the adjacent pair of blades among the plurality of blades. The centrifugal fan according to any one of claims 1 to 4, wherein the blade is the blade in the front in the rotation direction among the blades having the largest angle with the rotation center of the rotation shaft.
The blade having a radial length different from that of the other blades from the tip end side apex portion to the rear end side apex portion is the tip portion of each of the adjacent pair of blades among the plurality of blades. Any of claims 1 to 4, wherein the pair of blades is at least one of the blades in front of the rotation direction, which is larger than the average value of the angles formed by the rotation center of the rotation axis. The centrifugal fan according to item 1.
The length from the tip end side apex to the rear end side apex is different from that of other blades, and the length from the rotation center of the rotation axis to the tip end side apex is longer than the other blades. The centrifugal fan according to any one of claims 1 to 6, wherein the centrifugal fan is also short.
From claim 1, the length of each of the plurality of blades as seen from the rotation center of the rotation axis to the tip end side apex portion and the length to the rear end side apex portion are different for each of the blades. 7. The centrifugal fan according to any one of 7.
The stator housed in the casing and
A rotor rotatably supported by the casing inside the stator,
The centrifugal fan according to any one of claims 1 to 8, which is provided in the axial direction of the rotor and flows a fluid for cooling in the axial direction.
A rotary electric machine characterized by being equipped with.
The casing is provided with an intake portion having a plurality of openings facing the centrifugal fan.
The radial length from the rotation center of the rotation axis of the plurality of blades provided on the centrifugal fan to the end on the rear end side is
9. The rotary electric machine described in.
The casing has a flat surface portion perpendicular to the rotation axis facing the blades of the centrifugal fan on the radial outer side of the intake portion.
The radial overlap length of the flat surface portion facing the apex portion formed by the apex portion on the front end side and the apex portion on the rear end side of the blade is
The rotary electric machine according to claim 10, wherein the length in the axial direction between the apex portion and the flat surface portion is 1.5 times or more.
The rotary electric machine according to claim 10 or 11, wherein the outer diameter of the intake portion of the casing changes in the circumferential direction.
The rotary electric machine according to claim 11, wherein the flat surface portion of the casing has a donut shape whose center position is displaced from the rotation center of the rotation shaft.