JP7080743B2 - Electric blower and electric vacuum cleaner - Google Patents

Description

The present invention relates to an electric blower and an electric vacuum cleaner.

As disclosed in Patent Document 1 and Patent Document 2, a multi-blade fan having a plurality of fan blades (blades) is known. Such a multi-blade fan is provided in, for example, an electric blower or an electric vacuum cleaner, and is used as a source of airflow.

In the multi-blade fan disclosed in Patent Documents 1 and 2, each of the plurality of fan blades is curved so as to face forward with respect to the rotation direction. In other words, the central portion of the fan blade in the longitudinal direction warps toward the rear side in the rotational direction with respect to both ends in the longitudinal direction of the fan blade. Such a multi-wing fan functions as a so-called sirocco fan.

Patent Document 1 presents a method for improving the ventilation performance and reducing noise by providing an aileron between the main blades to reduce the change in the clearance dimension between the blades.

Patent Document 2 presents a method of providing a plurality of ailerons between main wings and setting the NZ sound to a high-frequency sound that is difficult for humans to hear.

On the other hand, there is also a rearward multi-wing fan (impeller) that functions as a so-called turbofan (radial fan). In such a multi-blade fan (hereinafter referred to as "impeller"), in a plan view, both tips in the longitudinal direction of the plurality of fan blades are the portions between the tips (specifically, the fan blades. It is curved so as to have a shape protruding rearward in the rotation direction from the central portion in the longitudinal direction). In other words, the portion between both tips in the longitudinal direction of the fan blade is warped toward the front side in the rotational direction with respect to both tips in the longitudinal direction of the fan blade.

Japanese Patent No. 38610402 (registered on October 6, 2006) Japanese Patent No. 4774609 (registered on July 8, 2011)

In the impeller, in general, a so-called slip phenomenon in which the airflow is separated is likely to occur in a portion of the negative pressure surface of the fan blade near the tip portion on the rear side in the rotation direction of the impeller. When the slip phenomenon occurs, the ventilation performance and the ventilation efficiency are lowered, and the noise is also increased.

In recent years, due to changes in lifestyle due to changes in housing conditions, there has been a strong demand for compact and lightweight electric vacuum cleaners, such as cordless electric vacuum cleaners that are handy (or stick type) and easy to operate. There is. In order to reduce the size and weight of an electric vacuum cleaner equipped with an electric blower equipped with an impeller, it is conceivable to reduce the size (smaller diameter) of the impeller, which is the main part thereof. However, downsizing (reducing the diameter) of the impeller tends to lead to a decrease in the suction power of the electric vacuum cleaner. As a measure to reduce the suction power, it is conceivable to significantly increase the rotation speed of the impeller, but the impeller with the increased rotation speed has the following concerns.

The dimension between the fan blades of the impeller increases from the inner diameter side to the outer diameter side of the impeller. Therefore, in the impeller, the air flow becomes unstable as the air moves from the inner diameter side to the outer diameter side of the impeller. As a result, problems such as a decrease in ventilation capacity and an increase in noise occur.

Further, in general, an air guide having a plurality of guide blades formed in an annular shape is arranged around the impeller. If the gap between the impeller and the air guide is narrowed in order to achieve high static pressure, abnormal noise called NZ noise is likely to occur. The NZ sound is proportional to the product of the number of fan blades and the number of rotations of the motor that rotates the fan blades. Therefore, as the rotation speed of the motor increases, the level of the NZ sound becomes very high. Conventionally, a motor used in a vacuum cleaner rotates at a rotation speed of about 3000 rpm. For example, when eight fan blades are used, an NZ sound is generated at 4000 Hz and its overtones.

Further, if the impeller is miniaturized (reduced in diameter), the fan blades cannot supply sufficient centrifugal force to the flow of wind flowing between adjacent fan blades. As a result, there is a concern that the slip phenomenon becomes large and the peeling area where the airflow separates becomes large. In particular, the fact that the diameter of the impeller becomes smaller and the distance between the fan blades becomes smaller, and that the separation area becomes large despite the small distance, lowers the blowing performance and the blowing efficiency of the electric blower. It acts synergistically with respect to that. Therefore, downsizing (reducing the diameter) of the impeller may lead to a great decrease in these performances and efficiencies.

In addition to the above concerns, as a result of significantly increasing the rotation speed of the impeller, turbulence such as vortices generated in the large separation area as described above collides with the fan blade located behind in the rotation direction at high speed. Therefore, there is a concern that extremely loud noise will be generated.

Further, by reducing the size (smaller diameter) of the impeller, the number of fan blades is restricted. For example, in the case of an impeller having a diameter (φ) of 50 mm or less, the thickness of the fan blade is generally set to about 1 mm. Specifically, for example, resin, aluminum, or the like is selected as the material of the fan blade, but the thickness of the fan blade is set to 0.5 to 1.5 mm from the viewpoint of the strength of the fan blade and the resin flow. ..

As described above, for example, Patent Document 2 discloses a proposal for providing an aileron between main wings in a multi-wing fan functioning as a sirocco fan to shift the NZ sound to a high frequency range that is difficult for humans to hear. However, the number of fan blades that can be arranged is limited depending on the thickness of the fan blades. Further, if the number of fan blades is increased, the distance between the adjacent fan blades becomes too narrow, and the ventilation performance is deteriorated. While the sirocco fan can arrange as many fan blades as 30 to 90 as main wings, the number of fan blades that can be arranged as main wings in a turbofan is about 13 at most. Therefore, the method of shifting the NZ sound to the high frequency range as described in Patent Document 2 cannot be applied to the conventional turbofan.

As a noise countermeasure, it is conceivable to adopt a sound deadening means using a sound absorbing material or the like, but the sound absorbing material contributes to an increase in weight or an increase in size. Therefore, it is not suitable to use a sound absorbing material or the like for, for example, a handy type cordless vacuum cleaner for which miniaturization and weight reduction are strongly desired.

In view of the above-mentioned circumstances, one embodiment of the present invention provides an electric blower and an electric vacuum cleaner capable of improving the blowing performance and the blowing efficiency as compared with the conventional case and further suppressing the generation of noise. The purpose.

In order to solve the above problems, the electric blower according to one aspect of the present invention includes a motor having a rotating shaft and an impeller attached to the rotating shaft, and the impeller includes a plurality of first fan blades. And a plurality of second fan blades, each of the plurality of first fan blades has a first tip portion located forward in the rotational direction of the impeller in the longitudinal direction thereof, and the rotational direction. It has a second tip portion located rearward in the above, and a portion between the first tip portion and the second tip portion extends so as to warp toward the front side in the rotational direction. 2 The tip portion is located inside in the radial direction from the outermost circumference of the impeller, and the second fan blade is from the first tip portion of each first fan blade adjacent to each other in the rotation direction to the first fan blade. A plurality of them are arranged between virtual lines extending along the extending direction to the outermost periphery of the impeller, and each of the plurality of second fan blades is viewed in a plan view, in the longitudinal direction thereof, and in the rotation direction. It has a third tip located in the front and a fourth tip located in the rear in the rotation direction. The fourth tip is located on the outermost periphery of the impeller, and the third tip is located. It is located on the same radius as the second tip, or is located radially inside the second tip and is located behind the rotation direction of the first fan blades adjacent to the second tip in the rotation direction. The shortest distance between the first fan blade and the second fan blade located at the rearmost position in the rotation direction among the plurality of second fan blades arranged between the virtual lines is d1, and the virtual The shortest distance between the second fan blades of one of the second fan blades adjacent to each other arranged between the lines and the second fan blade of the other is set to d2, and the second fan blades are arranged between the virtual lines. The shortest distance between the second fan blade located in the frontmost position in the rotation direction of the second fan blade and the first fan blade located in front of the rotation direction facing the rotation direction is d3. Then, 0.5 <(d1 + d3) / d2 <2.5.
In order to solve the above problems, the electric blower according to one aspect of the present invention includes a motor having a rotating shaft and an impeller attached to the rotating shaft, and the impeller includes a plurality of first fan blades. And a plurality of second fan blades, each of the plurality of first fan blades has a first tip portion located forward in the longitudinal direction of the impeller in the rotational direction of the impeller, and each of the plurality of first fan blades in the rotational direction. It has a second tip portion located rearward in the above, and a portion between the first tip portion and the second tip portion extends so as to warp toward the front side in the rotational direction. 2 The tip portion is located inside in the radial direction from the outermost circumference of the impeller, and the second fan blade is from the first tip portion of each first fan blade adjacent to each other in the rotation direction to the first fan blade. A plurality of them are arranged between virtual lines extending along the extending direction to the outermost periphery of the impeller, and each of the plurality of second fan blades is viewed in a plan view, in the longitudinal direction thereof, and in the rotation direction. It has a third tip located in the front and a fourth tip located in the rear in the rotation direction. The fourth tip is located on the outermost periphery of the impeller, and the third tip is located. It is located on the same radius as the second tip, or is located radially inside the second tip, and the diameter of the impeller is D, and the first tip and the first fan blade of the first fan blade. 2 Assuming that the length of the straight line connecting the tip portion is L1, 0.15 ≦ L1 / D ≦ 0.4 .
In order to solve the above problems, the electric blower according to one aspect of the present invention includes a motor having a rotating shaft and an impeller attached to the rotating shaft, and the impeller includes a plurality of first fan blades. And a plurality of second fan blades, each of the plurality of first fan blades has a first tip portion located forward in the rotational direction of the impeller in the longitudinal direction thereof, and the rotational direction. It has a second tip portion located rearward in the above, and a portion between the first tip portion and the second tip portion extends so as to warp toward the front side in the rotational direction. 2 The tip portion is located inside in the radial direction from the outermost circumference of the impeller, and the second fan blade is from the first tip portion of each first fan blade adjacent to each other in the rotation direction to the first fan blade. A plurality of them are arranged between virtual lines extending along the extending direction to the outermost periphery of the impeller, and each of the plurality of second fan blades is viewed in a plan view, in the longitudinal direction thereof, and in the rotation direction. It has a third tip located in the front and a fourth tip located in the rear in the rotation direction. The fourth tip is located on the outermost periphery of the impeller, and the third tip is located. Located on the same radius as the second tip, or located radially inside the second tip, the total number of second fan blades is z, and the rotation speed of the motor is n ( If s ^-1 ), then 8000 ≦ n × z, n ≧ 500, and z ≦ 33.

In order to solve the above problems, the electric vacuum cleaner according to one aspect of the present invention includes the electric blower according to one aspect of the present invention.

According to one aspect of the present invention, it is possible to provide an electric blower and an electric vacuum cleaner capable of improving the blowing performance and the blowing efficiency as compared with the conventional case and further suppressing the generation of noise.

It is a side view which shows the appearance of the electric vacuum cleaner which concerns on Embodiment 1. FIG. It is a perspective view which shows the appearance of the electric blower which concerns on Embodiment 1. FIG. It is a perspective view which shows the disassembled state of the electric blower which concerns on Embodiment 1. FIG. It is a perspective view which shows the state which disassembled the impeller which concerns on Example 1. FIG. (A) is a plan view showing an example of the arrangement of the first fan blade and the second fan blade in the impeller according to the first embodiment, and (b) is the lateral direction of the first fan blade shown in (a). (C) is a cross-sectional view of the second fan blade shown in (a) in the lateral direction. 5 is a plan view showing the outer shapes of the first fan blade and the second fan blade shown in FIGS. 5A to 5C together with a disk. It is a plan view of another main part which shows a part of FIG. 6 enlarged. It is a top view which shows an example of the arrangement of the fan blade in the impeller of the prior art which concerns on Comparative Example 1. FIG. It is a main part plan view explaining the slipping phenomenon in the impeller shown in FIG. It is a top view which shows an example of the arrangement of the main wing and the aileron in the impeller which concerns on the comparative example 2. FIG. It is a top view which shows an example of the arrangement of the main wing and the aileron in the impeller which concerns on the comparative example 3. FIG. It is a main part plan view explaining an example of the effect of the impeller which concerns on Example 1. FIG. It is a graph which compared the PQ characteristic of the impeller of Example 1 and the impeller of Comparative Example 1. It is a graph which compared the suction power of the impeller of Example 1 and the impeller of Comparative Example 1. It is a graph which compared the efficiency of the impeller of Example 1 and the impeller of Comparative Example 1. It is a graph comparing the noise level of Example 1 and Comparative Example 1 when the motor rotation speed is 50,000 rpm. It is a graph comparing the noise level of Example 1 and Comparative Example 1 when the motor rotation speed is 34000 rpm. It is a top view which shows an example of the arrangement of the 1st fan blade and the 2nd fan blade in the impeller which concerns on Example 2. FIG. It is a top view which shows an example of the arrangement of the 1st fan blade and the 2nd fan blade in the impeller which concerns on Reference Example 1. FIG. It is a top view which shows an example of the arrangement of the 1st fan blade and the 2nd fan blade in the impeller which concerns on the modification of Embodiment 1. FIG. It is a top view which shows an example of the arrangement of the 1st fan blade and the 2nd fan blade in the impeller which concerns on Example 3. FIG. It is a top view which shows an example of the arrangement of the 1st fan blade and the 2nd fan blade in the impeller which concerns on Reference Example 2. FIG. It is a top view which shows an example of the arrangement of the 1st fan blade and the 2nd fan blade in the impeller which concerns on Embodiment 3. FIG. It is a top view which shows an example of the arrangement of the 1st fan blade and the 2nd fan blade in the impeller which concerns on Embodiment 4. FIG.

Hereinafter, embodiments will be described with reference to the drawings. The same reference number is assigned to the same component and the corresponding component, and the description is not repeated for the component having the same reference number as the component described above.

[Embodiment 1]
(Electric vacuum cleaner 100)
FIG. 1 is a side view showing the appearance of the electric vacuum cleaner 100 according to the present embodiment. As shown in FIG. 1, the electric vacuum cleaner 100 includes a dust suction nozzle 10, an intake pipe 11, a support rod 12, a handle 13, a dust collection chamber 14, a main body portion 15, and an electric blower 20, and is a so-called handy type (or stick). The mold) can function as a cordless electric vacuum cleaner. The dust collecting chamber 14 may be a paper pack type or a cyclone type (centrifugal separation type). The electric blower 20 is arranged inside the main body 15, and the electric blower 20 generates an air flow, so that the dust and the like sucked through the dust suction nozzle 10 and the intake pipe 11 are sent to the dust collection chamber 14.

(Electric blower 20)
FIG. 2 is a perspective view showing the appearance of the electric blower 20, and FIG. 3 is a perspective view (partially a cross-sectional perspective view) showing a state in which the electric blower 20 is disassembled. As shown in FIGS. 2 and 3, the electric blower 20 includes an air guide 30, an impeller 40 (multi-blade fan), a case body 34, and a motor 38 (see FIG. 3).

As shown in FIG. 3, the air guide 30 includes an exterior portion 30a and a stationary blade portion 30b. The exterior portion 30a and the stationary wing portion 30b are configured as separate members from each other, and are integrated with each other to form the air guide 30. The exterior portion 30a has a tubular wall 31a and an inclined wall 31b, and a groove 31c for fitting a guide blade 32 provided in the stationary blade portion 30b is formed on the inner surface of the inclined wall 31b. The inner peripheral edge of the inclined wall 31b constitutes the suction port 31.

The stationary wing portion 30b includes a disc portion 32a having an annular shape, a plurality of guide blades 32 provided so as to stand up from the outer edge of the disc portion 32a toward the surface side (upper side in FIG. 3), and a disc portion. It has three blade plates 32c provided so as to hang down from the back surface of the 32a. A through hole 32b is formed in the disk portion 32a, and a screw or the like (not shown) is screwed into the boss portion 37b of the case body 34 (specifically, the plate 37 described later) through the through hole 32b. The stationary wing portion 30b is fixed to the case body 34.

The plurality of guide blades 32 are arranged in an annular shape, and the air guide 30 (static blade portion 30b) is arranged so that the plurality of guide blades 32 surround the impeller 40. The case body 34 includes a base 35, a motor housing 36 and a plate 37. The motor 38 is housed inside the motor housing 36, and the rotating shaft 38T of the motor 38 projects from the center of the plate 37. A discharge port 37H is formed on the plate 37. By attaching the air guide 30 to the plate 37, the impeller 40 is covered by the air guide 30 and the plate 37, and the blade plate 32c of the stationary blade portion 30b is arranged inside the discharge port 37H.

The impeller 40 is attached to the rotating shaft 38T using a bolt 39, and is rotationally driven by a motor 38 in the direction of arrow AR. By rotating the impeller 40, the suction port 31 of the air guide 30, the suction port 41H of the impeller 40, the inside of the impeller 40, the discharge port 46H of the impeller 40, the gap between the two adjacent guide wings 32, and the exhaust of the plate 37. An air flow that sequentially flows to the outlet 37H is generated. Here, the inside of the impeller 40 specifically includes a shroud 41, a fan blade 51 adjacent to each other in the rotation direction of the impeller 40 indicated by an arrow AR, and a fan blade 52 adjacent to each other in the rotation direction. , And the disk 44 indicates the space partitioned between them.

Hereinafter, the impeller 40 of the electric blower 20 according to the present embodiment will be described in detail with reference to examples.

<Example 1>
FIG. 4 is a perspective view showing a state in which the impeller 40 according to the present embodiment is disassembled. 5A is a plan view showing an example of arrangement of fan blades 51 and 52 in the impeller 40 according to the present embodiment, and FIG. 5B is a plan view showing the fan blades shown in FIG. 5A. It is a sectional view in the lateral direction of 51, and FIG. 5 (c) is a sectional view of the fan blade 52 in the lateral direction shown in FIG. 5 (a). As shown in FIGS. 4 and 5A, the impeller 40 has a shroud 41 and a disk 44, and as fan blades, a plurality of fan blades 51 (first fan blades) and ailerons which are main wings. It has a plurality of fan blades 52 (second fan blades). The disc 44 has a disk-shaped plate shape. A boss 47 is formed in the center of the surface 45 of the disk 44, and the boss 47 is provided with a through hole 48 for inserting the rotating shaft 38T (see FIG. 3). The back surface 46 of the disk 44 has a flat planar shape.

The shroud 41 has an annular plate shape curved so that the central portion exhibits a convex shape. The central portion of the shroud 41 forms a suction port 41H. The surface 42 of the shroud 41 is arranged so as to face the air guide 30 (exterior portion 30a shown in FIG. 3). The back surface 43 of the shroud 41 is integrated with a plurality of fan blades 51 and 52. As shown in FIG. 3, the shroud 41 is arranged such that the shroud 41 and the disk 44 sandwich the plurality of fan blades 51 and 52 from both outer sides in the direction of the rotation shaft 38T. Note that FIG. 4 illustrates how the shroud 41 is separated from the disk 44 and the plurality of fan blades 51 and 52.

As shown in FIGS. 4 and 5A, the plurality of fan blades 51 and 52 are arranged in an annular shape so as to be lined up along the rotation direction of the impeller 40, respectively, as indicated by the arrow AR, and by rotating. Blows air outward in the radial direction of rotation.

Each of the plurality of fan blades 51 is viewed in a plan view (in other words, when these fan blades 51 are viewed from above thereof), and one tip of each fan blade 51 in the longitudinal direction is the rotation of the impeller 40. It is located anterior to the other tip in the direction. Therefore, hereinafter, the one tip of each fan blade 51 is referred to as a front end portion 51F, and the other tip thereof is referred to as a rear end portion 51R. That is, each of the plurality of fan blades 51 has a front end portion 51F (first tip portion) located forward in the rotational direction and a rear end portion located rearward in the rotational direction in the longitudinal direction of each of the plurality of fan blades 51. It has 51R (second tip portion).

The fan blades 51 are provided so that their respective front end portions 51F surround the boss 47 at a position separated from the central boss 47 of the disk 44 by a certain distance from each other. The impeller 40 is a so-called backward-facing multi-wing fan. The fan blade 51 is such that, in a plan view, the portion between the front end portion 51F and the rear end portion 51R warps toward the front side in the rotational direction with respect to the front end portion 51F and the rear end portion 51R. It has a shape extending in a bow shape from the front end portion 51F to the rear end portion 51R. In other words, the fan blade 51 is curved so that the front side is convex and the rear side is concave with respect to the rotation direction. The rear end portion 51R of the fan blade 51 is located on the outer peripheral side of the disk 44 with respect to the front end portion 51F, and is radial with respect to the outer peripheral end 44a which is the outermost circumference of the disk 44 (in other words, the outermost circumference of the impeller 40). It is located inside.

Here, the radial direction is the direction connecting the center of the disk 44 and the outer peripheral end 44a of the disk 44 (in other words, the center of the impeller 40 and the impeller) as shown by the arrow AR1 in FIG. 5A. The direction connecting to the outermost circumference of 40) is shown. The fact that the rear end portion 51R of the fan blade 51 is located radially inside the outer peripheral end 44a of the disk 44 means that the rear end portion 51R of the fan blade 51 is located at the outer peripheral end of the disk 44 in the radial direction. It indicates that it is located closer to the center of the disk 44 than 44a. Therefore, when the rear end portion 51R of the fan blade 51 is located on the outer peripheral side of the disk 44 with respect to the front end portion 51F, the rear end portion 51R of the fan blade 51 is located radially outside the front end portion 51F. Show that.

Further, as shown in FIG. 5B, the fan blade 51 has a tapered shape, and has a width (thickness) in the lateral direction from the lower surface 51L side, which is the contact surface with the disk 44, to the upper surface 51U side. ) Becomes thinner. Therefore, each end surface (positive pressure surface 51P and negative pressure surface 51N) of the fan blade 51 in the lateral direction is inclined with respect to the surface 45 of the disk 44. Further, as shown in FIG. 5A, the length of the fan blade 51 in the longitudinal direction becomes shorter from the lower surface 51L side to the upper surface 51U side. Therefore, each end surface of the fan blade 51 in the longitudinal direction is also inclined with respect to the surface 45 of the disk 44. Therefore, the one tip (front end portion 51F) in the longitudinal direction of each fan blade 51 is the tip on the lower end side of the end surface of the radial inside (center side of the disk 44) of the disk 44 in the longitudinal direction of each fan blade 51. show. Further, the other tip (rear end portion 51R) in the longitudinal direction of each fan blade 51 is the lower end side of the end surface of the radial outside of the disk 44 (the outer peripheral end 44a side of the disk 44) in the longitudinal direction of each fan blade 51. Indicates the tip of. In FIG. 5A, the upper surface 51U is distinguished from the end faces other than the upper surface 51U of the fan blade 51 by hatching the end faces other than the upper surface 51U of the fan blade 51 in a plan view.

Similarly, each of the plurality of fan blades 52 is viewed in a plan view (in other words, when these fan blades 52 are viewed from above thereof), and one tip of each fan blade 52 in the longitudinal direction is an impeller. It is located in front of the other tip in the rotation direction of 40. Therefore, hereinafter, the one tip of each fan blade 52 is referred to as a front end portion 52F, and the other tip thereof is referred to as a rear end portion 52R. That is, each of the plurality of fan blades 52 has a front end portion 52F (third tip portion) located forward in the rotational direction and a rear end portion located rearward in the rotational direction in the longitudinal direction of each of the plurality of fan blades 52. It has 52R (fourth tip).

The fan blade 52 is such that, in a plan view, the portion between the front end portion 52F and the rear end portion 52R warps toward the front side in the rotational direction with respect to the front end portion 52F and the rear end portion 52R. It has a shape curved in a bow shape from the front end portion 52F to the rear end portion 52R. In other words, the fan blade 52 is curved so that the front side is convex and the rear side is concave with respect to the rotation direction. These fan blades 52 are provided on the outer peripheral portion of the disk 44. The rear end portion 52R of the fan blade 52 is located at the outer peripheral end portion 44a of the disk 44. Therefore, these fan blades 52 are provided on the outer peripheral portion of the disc 44 so as to be curved in a bow shape from the outer peripheral end 44a of the disc 44 toward the inside of the disc 44. In other words, the fan blade 52 is curved so that the front side is convex and the rear side is concave with respect to the rotation direction.

Further, as shown in FIG. 5 (c), the fan blade 52 has a tapered shape, and has a width (thickness) in the lateral direction from the lower surface 52L side, which is the contact surface with the disk 44, to the upper surface 52U side. ) Becomes thinner. Therefore, each end surface (positive pressure surface 52P and negative pressure surface 52N) of the fan blade 52 in the lateral direction is inclined with respect to the surface 45 of the disk 44. Further, as shown in FIG. 5A, the length of the fan blade 52 in the longitudinal direction becomes shorter from the lower surface 52L side to the upper surface 52U side. Therefore, each end surface of the fan blade 52 in the longitudinal direction is also inclined with respect to the surface 45 of the disk 44. Therefore, the one tip (front end portion 52F) in the longitudinal direction of each fan blade 52 is the tip on the lower end side of the end surface of the radial inside (center side of the disk 44) of the disk 44 in the longitudinal direction of each fan blade 52. show. Further, the other tip (rear end portion 52R) in the longitudinal direction of each fan blade 52 is the lower end side of the end surface of the radial outside of the disk 44 (the outer peripheral end 44a side of the disk 44) in the longitudinal direction of each fan blade 52. Indicates the tip of. In FIG. 5A, the upper surface 52U is distinguished from the end faces other than the upper surface 52U of the fan blade 52 by hatching the end faces other than the upper surface 52U of the fan blade 52 in a plan view.

When the impeller 40 rotates in the direction of arrow AR, the surface of the end surface (surface) in the lateral direction of the fan blade 51, which is located on the front side in the rotation direction, forms the positive pressure surface 51P and is located on the rear side in the rotation direction. The surface forms a negative pressure surface 51N. Similarly, of the end faces (surfaces) in the lateral direction of the fan blade 52, the surface located on the front side in the rotation direction forms the positive pressure surface 52P, and the surface located on the rear side in the rotation direction forms the negative pressure surface 52N. Will be done.

FIG. 6 is a plan view showing the outer shapes of the fan blades 51 and 52 shown in FIGS. 5A to 5C together with the disk 44. That is, in FIG. 6, as the fan blade 51, the shape of the lower surface 51L of the fan blade 51 shown in FIG. 5B, in other words, the contact end 51E (fan blade 51) of the fan blade 51 with the surface 45 of the disk 44. The shape of the root line) is shown. Further, in FIG. 6, as the fan blade 52, the shape of the lower surface 52L of the fan blade 52 shown in FIG. 5 (c), in other words, the contact end 51E (fan blade 52) of the fan blade 52 with the surface 45 of the disk 44. The shape of the root line) is shown.

As shown in FIG. 6, the fan blade 51 and the fan blade 52 are arranged at positions deviated from each other in the rotational direction. The fan blades 52 are formed from the front end portions 51F of the fan blades 51 adjacent to each other in the rotation direction (specifically, the front end portions 51aF and 51bF of the fan blades 51a and 51b shown in FIG. 7, which will be described later) to the fan blades 51. A plurality of virtual lines VL extending along the extending direction of the disk 44 to the outer peripheral end 44a of the disk 44 (in other words, the outermost periphery of the impeller 40) are arranged. By arranging a plurality of fan blades 52 between the virtual lines VL in this way, the number of fan blades 52 radially outside the fan blades 51 is larger than the number of fan blades 51 radially inside the fan blades 52. Can also be many.

As an example, in this embodiment, two fan blades 52 are arranged between adjacent virtual lines VL. More specifically, in this embodiment, two fan blades 52 are arranged in the region VR1 surrounded by the virtual line VL and the outer peripheral end 44a of the disk 44. As a result, in this embodiment, 22 fan blades 52 are provided for, for example, 11 fan blades 51. However, as shown in the embodiment described later, three or more fan blades 52 may be arranged between the virtual lines VL (in other words, in the region VR1).

It is desirable that a minimum gap (0.5 mm or more) that acts as a blade is provided between each fan blade. Here, the gap between the fan blades means, for example, a gap between the fan blades 51, a gap between the fan blades 52, and a gap between the fan blades 51 and 52. By providing the above-mentioned gap between the fan blades, each fan blade functions as an independent blade.

As shown in FIG. 6, the fan blade 52 is arranged so that the front end portion 52F of the fan blade 52 is located on the same radius as the rear end portion 51R of the fan blade 51. Here, "located on the same radius" means that the impeller 40 is located on the circumference of the same radius from the center. That is, the front end portion 52F of the fan blade 52 is, for example, a circular shape connecting the circular first fan blade rear end portion line 51RL connecting the rear end portions 51R of each fan blade 51 and the front end portion 52F of each fan blade 52. 2nd fan blade front end line 52FL is arranged so as to be located on the same circle (in other words, overlap with each other).

As described above, the fan blade 52 is a virtual line extending from the front end portion 51F of each fan blade 51 adjacent to each other in the rotation direction of the impeller 40 to the outer peripheral end 44a of the disk 44 along the extending direction of each fan blade 51. It is arranged between VL. Therefore, the front end portion 52F of the fan blade 52 and the rear end portion 51R of the fan blade 51 are located on the same radius, so that they are located on the front side in the rotation direction of the fan blades 52 arranged between the virtual lines VL. A predetermined position in the rotation direction is provided between the front end portion 52F of the fan blade 52 and the rear end portion 51R of the fan blade 51 located in front of the rotation direction so as to face the front end portion 52F in the rotation direction. A gap (gap S3 described later) can be provided.

FIG. 7 is a plan view of a main part showing a part of FIG. 6 in an enlarged manner. As described above, in this embodiment, two fan blades 52 are arranged between the virtual lines VL (in other words, in the area VR1). Hereinafter, for convenience of explanation, as shown in FIG. 7, among the fan blades 52 located in the region VR1, the fan blades 52 located behind the impeller 40 in the rotation direction (in other words, between the virtual lines VL (inside the region VR1)). Of the fan blades 52 arranged in the above, the fan blade 52 (rear side second fan blade) located at the rearmost position in the rotation direction is referred to as a fan blade 52a. Further, among the fan blades 52 located in the region VR1, the fan blades 52 located in front of the impeller 40 in the rotation direction (in other words, the fan blades 52 arranged between the virtual lines VL (inside the region VR1) rotate. The fan blade 52 (front side second fan blade) located at the frontmost position in the direction is referred to as a fan blade 52b. Further, the front end portion 52F of the fan blade 52a is referred to as a front end portion 52aF, and the front end portion 52F of the fan blade 52b is referred to as a front end portion 52bF. The rear end portion 52R of the fan blade 52a is referred to as a rear end portion 52aR, and the rear end portion 52R of the fan blade 52b is referred to as a rear end portion 52bR. Further, the negative pressure surface 52N of the fan blade 52a is referred to as a negative pressure surface 52aN, and the negative pressure surface 52N of the fan blade 52b is referred to as a negative pressure surface 52bN. Further, the positive pressure surface 52P of the fan blade 52a is referred to as a positive pressure surface 52aP, and the positive pressure surface 52P of the fan blade 52b is referred to as a positive pressure surface 52bP.

Similarly, when focusing on one region VR1, it is located behind the rotation direction among the two fan blades 51 adjacent to each other in the rotation direction of the impeller 40 constituting the region VR1, and is located between the virtual lines VR (inside the region VR1). ), The fan blade 51 (the first fan blade on the rear side) adjacent to the fan blade 52a is referred to as a fan blade 51a, which is located forward in the rotation direction and is adjacent to the fan blade 52b between the virtual lines VR. The front side first fan blade) is referred to as a fan blade 51b. Further, the front end portion 51F of the fan blade 51a is referred to as a front end portion 51aF, and the front end portion 51F of the fan blade 51b is referred to as a front end portion 51bF. The rear end portion 51R of the fan blade 51a is referred to as a rear end portion 51aR, and the rear end portion 51R of the fan blade 51b is referred to as a rear end portion 51bR. Further, the negative pressure surface 51N of the fan blade 51a is referred to as a negative pressure surface 51aN, and the negative pressure surface 51N of the fan blade 51b is referred to as a negative pressure surface 51bN. Further, the positive pressure surface 51P of the fan blade 51a is referred to as a positive pressure surface 51aP, and the positive pressure surface 51P of the fan blade 51b is referred to as a positive pressure surface 51bP. However, in the region VR1 adjacent to the region VR1 in the front in the rotation direction, the fan blade 51b becomes the fan blade 51a. Further, in the region VR1 adjacent to the region VR1 rearward in the rotation direction, the fan blade 51a becomes a fan blade 51b.

As shown in FIG. 7, between the fan blade 51a and the fan blade 52a, between the fan blade 52a and the fan blade 52b, and between the fan blade 52b and the fan blade 51b (that is, between the fan blade 51a and the fan blade 52a). A gap is formed between the facing surfaces of the fan blades 52a and the fan blades 52b, and between the facing surfaces of the fan blades 52b and the fan blades 51b).

Of the regions between the fan blades 52 adjacent to each other in the rotation direction, the region located on the rear end portion 51R side of the fan blade 51 is defined as the region VR2, and the other region (in other words, the surface facing the rear end portion 51R of the fan blade 51). Assuming that the region (not included) is region VR3, the inflow amount of air flowing into each region VR2 / VR3 can be adjusted by changing the shortest distance of the above-mentioned gap.

Here, the shortest distance between the fan blades 51a and the fan blades 52a is d1, the shortest distance between the fan blades 52a and the fan blades 52b is d2, and the fan blades 52b and the fan blades 51b Assuming that the shortest distance between the gaps is d3, in this embodiment, each fan blade is preferably arranged so that 0.5 <(d1 + d3) / d2 <2.5 holds. The shortest distance d1 of the gap between the fan blades 51a and the fan blades 52a is arranged between the fan blades 51a located behind the fan blades 51 in the rotation direction and the virtual line VL among the fan blades 51 adjacent to each other in the rotation direction. The shortest gap between the fan blades 52 and the fan blades 52a adjacent to the fan blades 51a (that is, between the facing surfaces of the fan blades 51a and the fan blades 52a), which is located at the rearmost position in the rotation direction. Indicates the distance. Further, the shortest distance d2 of the gap between the fan blades 52a and the fan blades 52b is between the adjacent fan blades 52 (that is, between the fan blades 52a and the fan blades 52b) arranged between the virtual lines VL. The shortest distance between the facing surfaces of the fan blades 52a and the fan blades 52b) is shown. Further, the shortest distance d3 of the gap between the fan blades 52b and the fan blades 51b is arranged between the fan blades 51b located in front of the fan blades 51 in the rotation direction and the virtual line VL among the fan blades 51 adjacent to each other in the rotation direction. Of the fan blades 52, which is located at the frontmost position in the rotation direction, in the rotation direction between the fan blades 52b adjacent to the fan blades 51b (that is, between the facing surfaces of the fan blades 51b and the fan blades 52b). Shows the shortest distance of the gap.

As described above, the fan blades 51 and 52 are formed so that both the length in the longitudinal direction and the width in the lateral direction are smaller toward the upper surfaces 51U and 52U, respectively. Therefore, as shown in FIG. 7, in this embodiment, the shortest distance d1 of the gap between the fan blade 51a and the fan blade 52a (that is, the gap between the facing surfaces of the fan blade 51a and the fan blade 52a). The shortest distance) is the gap between the tip of the fan blade 51a on the rear end 51aR side at the lower end of the positive pressure surface 51aP and the lower end of the negative pressure surface 52aN of the fan blade 52a facing the tip (hereinafter, "gap S1"). It becomes the distance of). As shown in FIG. 7, the d1 has a circle in contact with the tip of the fan blade 51a on the rear end 51aR side at the lower end of the positive pressure surface 51aP and the lower end of the negative pressure surface 52aN of the fan blade 52a facing the tip. When drawn, it is indicated by its diameter (φ).

Further, the shortest distance d2 of the gap between the fan blade 52a and the fan blade 52b (that is, the shortest distance of the gap between the facing surfaces of the fan blade 52a and the fan blade 52b) is the positive pressure surface 52aP of the fan blade 52a. This is the distance between the tip of the front end portion 52aF at the lower end of the fan blade and the lower end of the negative pressure surface 52bN of the fan blade 52b facing the tip (hereinafter referred to as “gap S2”). As shown in FIG. 7, the d2 draws a circle in contact with the tip of the fan blade 52a on the front end 52aF side at the lower end of the positive pressure surface 52aP and the lower end of the negative pressure surface 52bN of the fan blade 52b facing the tip. When, it is indicated by its diameter (φ).

The shortest distance d3 of the gap between the fan blade 52b and the fan blade 51b (that is, the shortest distance between the facing surfaces of the fan blade 52b and the fan blade 51b) is the front end portion 52bF of the fan blade 52b. It is the distance between the fan blade 51b and the rear end portion 51bR (specifically, the gap in the rotation direction, hereinafter referred to as "gap S3"). The shortest distance between the fan blades 52b and the fan blades 51b is between the fan blades 51a and the fan blades 52 adjacent to the fan blades 51a and located behind the fan blades 51a in the rotational direction. It can be said that it is the shortest distance of the gap. As shown in FIG. 7, the above d3 is shown by the diameter (φ) of, for example, when drawing a circle in contact with the front end portion 52bF of the fan blade 52b and the rear end portion 51bR of the fan blade 51b. The d3 is when a circle having a diameter in the rotation direction is drawn between the fan blades 52b and the fan blades 51b adjacent to the fan blades 52b in the rotation direction and facing each other in the rotation direction. It can also be said that it is indicated by the diameter (φ) of the smallest circle.

The gap S2 is the minimum passage for the air flowing into the region VR3, and serves as an inflow port for the air to the region VR3.

The gap S1 is the minimum passage for air flowing into the region VR2 from the positive pressure surface 51P side of the fan blade 51, and serves as an air inlet to the region VR2. More specifically, the gap S1 is the minimum passage of air flowing into the region VR2 from the positive pressure surface 51aP side of the fan blade 51a.

The gap S3 is the minimum passage for air flowing into the region VR2 from the negative pressure surface 51N side of the fan blade 51, and serves as an air inlet to the region VR2. More specifically, the gap S3 is the minimum passage of air flowing into the region VR2 from the negative pressure surface 51aN side of the fan blade 51a, and from a different point of view, the gap S3 is from the negative pressure surface 51bN side of the fan blade 51b. It is the minimum passage of air flowing into the region VR2 located in front of the fan blade 51b in the rotation direction.

By setting (d1 + d3) / d2 within the above range, the difference between the inflow amount of air flowing into the region VR2 and the inflow amount of air flowing into the region VR3 can be reduced. It is more preferable that the above d1 to d3 are set so that 1 <(d1 + d3) / d2 <1.5. Thereby, the difference in the inflow amount of the air flowing into each region VR2 and VR3 can be further reduced. According to this embodiment, by adjusting the difference in the inflow amount of the air flowing into each region VR2 and VR3 in this way, the pressure fluctuation generated in the outer peripheral portion of the impeller 40 (in other words, the rear end portion of the fan blade 52). It is possible to reduce the pressure fluctuation) that occurs in 52R. According to this embodiment, when (d1 + d3) / d2 = 1.35, the pressure fluctuation can be reduced more effectively.

As shown in FIG. 4, the shroud 41 and the disk 44 have the same size in a plan view. Therefore, the diameter of the impeller 40 is equal to the diameter of the shroud 41 and the disc 44, respectively. As shown in FIG. 5, where D is the diameter of the disk 44 (in other words, the diameter of the impeller 40), d1 is set within the range of 0.01 <d1 / D <0.046. In this embodiment, the diameter D (φ) of the impeller 40 (disk 44) is 44 mm, and is set to, for example, d1 = 0.79 mm and d1 / D = 0.018. By setting 0.01 <d1 / D <0.046 in this way, the air having higher kinetic energy flowing along the positive pressure surface 51P of the fan blade 51 (described later, is indicated by the arrow DR1 shown in FIG. 12). The airflow) can be effectively poured into the rear end portion 52R of the fan blade 52, and the effect of suppressing the separation of the airflow in the separation region can be further enhanced.

As described above, in the case of an impeller having a diameter D (φ) of 50 mm or less, the thickness of the fan blade (in other words, the width in the lateral direction) is generally set to about 1 mm. Specifically, for example, resin, aluminum, or the like is selected as the material of the fan blade, but the thickness of the fan blade is set to 0.5 to 1.5 mm from the viewpoint of the strength of the fan blade and the resin flow. .. In this embodiment, the thickness of the lower surface 51L of the fan blade 51 (in other words, the maximum thickness of the fan blade 51 (the maximum width in the lateral direction)) and the thickness of the lower surface 52L of the fan blade 52 (in other words, the fan blade 52). The maximum thickness (maximum width) in the lateral direction was set to, for example, 1.06 mm.

Further, as shown in FIG. 7, the length of the straight line L connecting the front end portion 51F and the rear end portion 52R of the fan blade 51 is L1 (note that even in the embodiment described later, L1 indicates the above length). It is desirable that L1 is set within the range of 0.15 ≦ L1 / D ≦ 0.4. This makes it possible to improve the ventilation performance and the ventilation efficiency. In this embodiment, L1 is set so that L1 = 15.89 mm and L1 / D = 0.36.

In this embodiment, for example, when L1 / D = 0.1, the fan blade 51 itself becomes shorter and the length of the fan blade 51 in the radial direction becomes shorter. Further, since the rear end portion 52R of the fan blade 52 is located at the outer peripheral end 44a of the disk 44 and the front end portion 52F is located on the same radius as the rear end portion 51R of the fan blade 51, the fan blade 52 becomes longer. In this case, it may not be possible to supply high kinetic energy from the gap S1. When high kinetic energy cannot be supplied from the gap S1, a portion of the negative pressure surface 52N of the fan blade 52 near the rear end portion 52R, which is the tip end portion on the rear side in the rotation direction of the impeller 40 (that is, the fan blade 52). The peeling phenomenon is likely to occur at the tip of the negative pressure surface 52N on the rear end portion 52R side). Further, for example, when L1 / D = 0.6, the fan blade 52 may become too short and may not play a role as a fan blade.

Therefore, it is desirable that L1 is set within the range of 0.15 ≦ L1 / D ≦ 0.4. This makes it possible to improve the blowing performance and blowing efficiency of the electric blower 20 and to obtain a quiet effect.

In this embodiment, the fan blade 52 is located between the virtual lines VL described above (inside the region VR1), the rear end portion 52R is located at the outer peripheral end 44a of the disk 44, and the front end portion 52F is the rear end of the fan blade 51. As long as it is provided on the same radius as the portion 51R, its length is not particularly limited. Since the fan blade 52 is provided between the virtual lines VL described above, the front end portion 52F of the fan blade 52 is from the front end portion 51aF of the fan blade 51a located rearward in the rotation direction among the fan blades 51a and 51b. Is also formed so as to be located on the outer side in the radial direction.

The fan blade 52 has a minimum gap (0.5 mm or more) that acts as a wing between each fan blade according to the diameter D (φ) of the impeller 40 (disk 44) and the number of fan blades 51 and 52. It suffices if it is formed as follows.

However, if the fan blades 51 and 52 become too short, they will not play a role as fan blades. Therefore, the fan blades 51 and 52 have a diameter of 5 mm or more regardless of the diameter D (φ) of the impeller 40 (disk 44). It is desirable to have a length.

Further, as the number of fan blades 52 increases, the gap between the fan blades becomes narrower. If the distance between adjacent fan blades becomes too small, the ventilation performance may deteriorate. Therefore, assuming that the total number of fan blades 52 is z, it is desirable that z ≦ 33. According to the above configuration, it is possible to secure a minimum gap (0.5 mm or more) that acts as a blade between the fan blades and suppress deterioration of the ventilation performance.

Further, when the length of the straight line K connecting the front end portion 52F and the rear end portion 52R of the fan blade 52 is K1 (note that K1 also indicates the above length in the embodiment described later), K1 is , 0.1 <K1 / D ≦ 0.25 is preferably set. When K1 / D = 0.2 (K1 = 8.91 mm in this embodiment), the fan blade 51 can most effectively utilize the high kinetic energy flowing along the positive pressure surface 51P of the fan blade 51, and is peeled off. It is optimal because it can maximize the suppressive effect of.

For example, when K1 / D> 0.25, the air flowing into the region VR2 from the gap S1 between the fan blade 51 and the fan blade 52 in the vicinity of the rear end portion 51R of the fan blade 51 is the negative pressure surface 52N of the fan blade 52. However, the distance of the negative pressure surface 52N is long, and the fan blade 52 may peel off near the tip of the negative pressure surface 52N on the rear end portion 52R side, and the ventilation performance may deteriorate.

Further, a portion where the fan blade 51a located rearward in the rotation direction in the extension direction of the fan blade 51 and the fan blade 52a located rearward in the rotation direction among the fan blades 52a and 52b arranged between the virtual lines VL face each other. When the length of is W (in addition, even in the embodiment described later, W indicates the above length), W is set within the range of 0.04 ≦ W / D ≦ 0.11. Is desirable. Here, the length W is specifically a line connecting the rear end portion 51aR of the fan blade 51a and the lower end of the negative pressure surface 52aN of the fan blade 52a at the shortest distance, and the front end portion 52aF of the fan blade 52a. The linear distance between the fan blade 51a and the line connecting the lower end of the positive pressure surface 51aP of the fan blade 51a with the shortest distance is shown.

For example, when W / D = 0.13 (W = 5.7 mm), the kinetic energy of the air flowing into the gap S1 between the fan blade 51a and the fan blade 52a decreases in the vicinity of the rear end portion 51aR of the fan blade 51a. However, there is a possibility that the separation of the airflow cannot be suppressed near the tip of the fan blade 52a on the rear end 52aR side of the negative pressure surface 52aN. This is because the distance of W becomes long and the energy loss becomes large.

Further, for example, when W / D = 0.03 (W = 1.3 mm), the amount of air sneaking into the positive pressure surface 52aP side of the fan blade 52a increases, and the amount of air poured into the gap S1 decreases. In this embodiment, W is set to 3.29 mm.

Next, the effect of the impeller 40 according to this embodiment will be described with reference to a comparative example.

<Comparative Example 1>
FIG. 8 is a plan view showing an example of the arrangement of the fan blades 151 in the impeller 140 of the prior art according to this comparative example. For comparison, the impeller 140 has the same design as the impeller 40 except for the following points. The impeller 140 is provided with a plurality of fan blades 151 instead of the plurality of fan blades 51 and 52. Each of the plurality of fan blades 151 has a front end portion 151F located forward in the rotation direction of the impeller 140 and a rear end portion 151R located rearward in the rotation direction, as indicated by the arrow AR. The fan blades 151 are provided so that their respective front end portions 151F surround the boss 47 at a position separated from the central boss 47 of the disk 44 by a certain distance from each other. The fan blade 151 has a shape extending in a bow shape from the front end portion 151F to the rear end portion 151R so that the portion between the front end portion 151F and the rear end portion 151R warps toward the front side in the rotational direction. have. The rear end portion 151R of the fan blades 151 is located at the outer peripheral end portion 44a of the disk 44. The impeller 140 is provided with eight fan blades 151 having a thickness (maximum thickness) of 1.06 mm.

FIG. 9 is a plan view of a main part for explaining the slip phenomenon in the impeller 140 shown in FIG. As shown in FIG. 9, in the impeller 140, which is a rear-facing multi-blade fan (turbofan), a plurality of fan blades 151 are curved so as to be rearward with respect to the rotation direction indicated by AR. In such a rear-facing multi-blade fan, a so-called slip phenomenon is generally likely to occur in the vicinity of the rear end portion 151R on the negative pressure surface 151N side of the fan blade 151. Specifically, an air flow is generated by the rotation of the fan blade 151. The kinetic energy of the airflow indicated by the arrow DR11 flowing along the negative pressure surface 151N of the fan blade 151 decreases from the front end portion 151F side to the rear end portion 151R side of the fan blade 151. The separation of the airflow from the negative pressure surface 151N as shown by the arrow DR12 as the kinetic energy decreases is called a slip phenomenon. When the slip phenomenon occurs, the blowing performance and the blowing efficiency of the electric blower provided with the impeller 140 are lowered, and the noise is also increased.

<Comparative Example 2>
FIG. 10 is a plan view showing an example of the arrangement of the fan blades 151 and 152 in the impeller 240 according to this comparative example. In the impeller 240, the fan blade 151 of the impeller 140 shown in FIG. 8 is used as a main wing, and a fan blade 152 having the same blade thickness as the fan blade 151 is provided as an aileron between adjacent fan blades 151. For the fan blade 152, a fan blade having the same configuration as that of the fan blade 52 was used. Further, in FIG. 10, 11 fan blades 151 are arranged, and one fan blade 152 is arranged between adjacent fan blades 151. Therefore, the impeller 240 is provided with a total of 22 fan blades 151 and 152.

<Comparative Example 3>
FIG. 11 is a plan view showing an example of the arrangement of the fan blades 151 and 152 in the impeller 340 according to this comparative example. In the impeller 340, two fan blades 152 are arranged between the fan blades 151 of the impeller 240 shown in FIG. Therefore, the impeller 340 is provided with a total of 33 fan blades 151 and 1521.

<Effect of Example 1>
Here, the effects of Example 1 on Comparative Examples 1 to 3 will be described below with reference to FIGS. 12 to 17. FIG. 12 is a plan view of a main part for explaining an example of the effect of the impeller 40 according to the first embodiment. Note that FIG. 12 shows the outer shape of the fan blades 51 and 52 (the shape of the root line of the fan blades 51 and 52) as the fan blades 51 and 52.

In the first embodiment, as described above, the number of fan blades 52 on the outer side in the radial direction is 22, which is set to be twice that of the 11 fan blades 51. Therefore, according to the first embodiment, the fan blade 52 is located near the tip on the rear end 52R side of the negative pressure surface 52N of the fan blade 52 on the outer peripheral portion of the disk 44, where the peeling phenomenon is likely to occur in the rearward multi-blade fan. The distance between them can be set so that they are not far apart from each other. In the first embodiment, the fan blades 52 are arranged at equal intervals.

Normally, in an impeller (multi-blade fan), for example, as shown in FIG. 8, the distance between the fan blades 151 adjacent to each other in the rotation direction increases from the inside in the radial direction to the outside in the radial direction, and the air flow becomes unstable. become. However, according to the first embodiment, the number of fan blades 52 located relatively outward in the radial direction among the fan blades 51 and 52 is larger than the number of fan blades 51 located relatively inward in the radial direction. As a result, it is possible to suppress large fluctuations in the dimensions between the adjacent fan blades in the rotation direction.

In Comparative Examples 2 and 3, as shown in FIGS. 10 and 11, the fan blade 152 can be arranged as an aileron, and by arranging the fan blade 152, the fan blades adjacent to each other in the rotation direction can be arranged. It is possible to suppress large fluctuations in the dimensions between them. However, in Comparative Examples 2 and 3, the area between the main wing and the aileron is narrow because the fan blade 151, which is the main wing, is provided up to the outer peripheral end 44a of the disk 44. Therefore, in Comparative Examples 2 and 3, the blowing performance is lower than that in Comparative Example 1. Therefore, normally, it is necessary to reduce the number of fan blades 151 to secure a desired region.

However, according to this embodiment, as shown in FIG. 12, the rear end portion 51R of the fan blade 51 is located radially inside the outermost circumference of the impeller 40 (in other words, the outer peripheral end 44a of the disk 44). As described above, a plurality of fan blades 52 that function as independent blades can be provided between the adjacent fan blades 51 (more specifically, in the region VR1 shown in FIGS. 6 and 7). Therefore, according to the first embodiment, the fan blades 52 can be arranged more effectively as compared with the case where the fan blades 152 are arranged between the fan blades 151 as shown in Comparative Examples 2 and 3. .. Therefore, according to the first embodiment, it is possible to improve the blowing performance after arranging 11 fan blades 51 and 22 fan blades 52 as described above.

Further, according to the present embodiment, by increasing the number of fan blades 52 that function as independent blades in this way, the work performed by the fan blades 52 can be divided, and the rear end of each fan blade 52 can be divided. The pressure fluctuation between the portions 52R can be reduced. Therefore, it is possible to reduce the noise caused by the pressure fluctuation.

Further, as described above, when the front end portion 52F of the fan blade 52 and the rear end portion 51R of the fan blade 51 are located on the same radius, the rotation of the front end portion 52bF of the fan blade 52b and the front end portion 52bF. A predetermined gap S3 is formed in the rotational direction with the rear end portion 51R of the fan blade 51 facing in the direction. Therefore, as shown by the arrows DR3 and DR4, air flows from the negative pressure surface 51N side of the fan blade 51 through the gap S3 into the region VR2, and the air flows into the negative pressure surface 52aN of the fan blade 52a. It flows into the vicinity of the tip on the rear end 52aR side. Further, as described above, a predetermined gap (a predetermined gap) is provided between the tip of the fan blade 51a on the rear end portion 51aR side at the lower end of the positive pressure surface 51aP and the lower end of the negative pressure surface 52aN of the fan blade 52a facing the tip. A gap S1) is formed. As a result, the air having higher kinetic energy (air flow indicated by the arrow DR1 shown in FIG. 12) flowing along the positive pressure surface 51P of the fan blade 51 flows from the gap S1 to the rear end portion 52aR of the negative pressure surface 52aN of the fan blade 52a. Effectively poured near the tip of the side. The flow rate of the air flowing into the region VR2 is determined by the dimensions of d1 + d3. Further, the flow rate of the air flowing into VR3 is determined by the dimension of d2. Therefore, the air flow rate (air volume) in each region VR2 / VR3 adjusts the inflow amount of air flowing into each region VR2 / VR3 by adjusting d1 to d3 (in other words, the size of the gaps S1 to S3). By doing so, adjustment is possible.

In the first embodiment, for example, d1 = 0.79 mm, d2 = 1.59 mm, and d3 = 1.32 mm are set, and the arrangement is such that (d1 + d3) / d2 = 1.33. According to the first embodiment, it is possible to make the flow rates of air in the region VR2 and the region VR3 equal to each other, and it is possible to suppress the pressure fluctuation in the outer peripheral portion of the impeller 40 to the minimum.

When the fan blades 51 and 52 are arranged so that the front end portion 52F of the fan blade 52 is located radially outside the rear end portion 51R of the fan blade 51, the frequency of the NZ sound (NZ frequency) is set to a high frequency. Even if it is possible to reduce the noise by setting it in the band, the noise reduction effect cannot be obtained due to the large pressure fluctuation, and the ventilation performance may be deteriorated. This point will be described later with reference to a comparative example.

Further, as described with reference to FIG. 9, in a rearward-facing multi-blade fan, a slip phenomenon is generally likely to occur in the vicinity of the rear end portion 151R on the negative pressure surface 151N side of the fan blade 151. In Example 1, the location (peeling area) where the slip phenomenon can occur is near the tip of the fan blade 52a on the negative pressure surface 52aN near the tip of the rear end portion 52aR side and the rear end of the fan blade 52b on the negative pressure surface 52bN. It is near the tip on the portion 52bR side.

However, as described above, in the first embodiment, air having a higher kinetic energy flows into the region VR2 from the gap S3 and flows along the positive pressure surface 51P of the fan blade 51 (arrows in FIG. 12). The airflow (airflow shown by DR1) flows through the gap S1. Thereby, according to the first embodiment, it is possible to physically suppress the air flow from peeling from the negative pressure surface 52aN in the vicinity of the tip end portion (peeling area) on the rear end portion 52aR side in the negative pressure surface 52aN. It is possible to suppress the slipping phenomenon in the peeling area. Therefore, it is possible to suppress the deterioration of the ventilation performance and the ventilation efficiency and the noise caused by the slip phenomenon.

Further, in the region VR3, the gap S2, which is the inlet of the airflow indicated by the arrow DR2 in FIG. 12, to the region VR3 is provided wider than, for example, the gaps S1 and S3. In other words, d2 is set larger than d1 and d3. As a result, in Example 1, as described above, (d1 + d3) / d2 = 1.33, and 0.5 <(d1 + d3) / d2 <2.5 is satisfied. As a result, it is possible to secure kinetic energy in the negative pressure surface 52bN of the fan blade 52b so that the airflow does not separate near the tip on the rear end portion 52bR side. As a result, it is possible to suppress the slipping phenomenon in the vicinity (peeling area) of the rear end portion 52bR, and it is possible to suppress the deterioration of the blowing performance and the blowing efficiency and the noise caused by the slipping phenomenon, and also to suppress the noise of the disk 44. It is possible to improve the ventilation performance while suppressing the pressure fluctuation generated at the outer peripheral end 44a.

Therefore, when a general multi-blade fan is miniaturized (reduced in diameter), the peeling region becomes larger as the kinetic energy in the vicinity of the rear end portion 151R on the negative pressure surface 151N side of the fan blade 151 decreases, and the slip phenomenon occurs. However, according to the first embodiment, such a concern can be reduced. According to the first embodiment, even when the impeller 40 is miniaturized (reduced in diameter) or the impeller 40 is rotated at a high speed (in other words, a high-speed rotation drive), the ventilation performance and the ventilation efficiency are improved. It is possible to suppress the decrease and the increase in noise.

Further, according to the first embodiment, by increasing the number of fan blades 52 on the outer peripheral portion of the impeller 40 as described above, the NZ frequency generated by the rotation of the motor 38 is set to the high frequency band (high temperature region which is difficult for humans to hear). ) Can be moved.

For example, when the impeller 140 shown in FIG. 8 is rotated at a rotation speed of 30,000 rpm (500s ^-1 ), the NZ frequency becomes 500 × 8 = 4000 Hz, and a jarring sound (a humming band sound) is generated. On the other hand, when the impeller 40 according to the first embodiment is used, the NZ frequency becomes 500 × 22 = 11000 Hz when the impeller 40 is rotated at a rotation speed of 30,000 rpm (500s ^-1 ). As described above, according to the first embodiment, the NZ frequency can be set to a high frequency band of 80,000 Hz or higher, which is a band that is difficult for humans to hear.

Further, recently, a small motor having a high rotation speed of 50,000 rpm or more has been developed. Therefore, when, for example, a motor having a rotation speed of 50,000 rpm (833s ^-1 ) is used as the motor 38, the NZ frequency becomes 833 × 22 = 18333 Hz, and it becomes possible to more effectively reduce the noise. Further, when the rotation speed is 65000 rpm (1083s ^-1 ), the NZ frequency is 1083 × 22 = 23826 Hz, and by setting it to 20 kHz or more, which is outside the human audible range, it is possible to further effectively reduce the noise.

As described above, assuming that the total number of fan blades 51 is z and the rotation speed of the motor 38 is n (s ^-1 ), 8000 ≦ n × z, n ≧ 500, and z ≦ 33. desirable. As a result, the frequency of the NZ sound that is offensive to the ear can be shifted to a high frequency band of 8000 Hz or higher, which is difficult for humans to hear, and noise can be improved.

13 to 17 are graphs comparing the performance of the impeller 40 of the first embodiment and the impeller 140 of the comparative example 1. FIG. 13 is a graph showing PQ characteristics, FIG. 14 is a graph showing suction work rate, which is an index of vacuum cleaner performance, and FIG. 15 is a graph showing efficiency (work efficiency), each of which is the rotation speed of the motor 38 (hereinafter referred to as “rotary speed”). , "Motor rotation speed") is a summary of the measurement results at 50,000 rpm.

From the results shown in FIGS. 13 to 15, it can be confirmed that the static pressure and the air volume are improved on the operation curve in which the electric blower 20 provided with the impeller 40 according to the first embodiment is actually incorporated in the electric vacuum cleaner 100. As described above, in Comparative Examples 2 and 3, the ventilation performance is lower than that in Comparative Example 1. Therefore, the measurement results are omitted.

16 and 17 are graphs comparing the noise levels of Example 1 and Comparative Example 1, and FIG. 17 shows the results when the motor rotation speed is 50,000 rpm. The noise level (overall value) is reduced to 72.06 dB in Example 1 as opposed to 76.86 dB in Comparative Example 1. Therefore, from the results shown in FIGS. 13 to 17, it can be seen that, according to the first embodiment, it is possible to simultaneously improve the ventilation performance and the ventilation efficiency and reduce the noise. Further, FIG. 17 shows the result when the motor rotation speed is 34000 rpm. The noise level (overall value) is reduced to 64.52 dB in Example 1 while it is 66.49 dB in Comparative Example 1. When the motor rotation speed is 34000 rpm (567s ^-1 ), the NZ frequency is 567 × 22 = 12467 Hz. When the motor rotation speed is 50,000 rpm, the NZ frequency is 18333 Hz. Therefore, when the motor rotation speed is 50,000 rpm, a higher effect can be obtained than when the motor rotation speed is 34,000 rpm.

<Example 2>
FIG. 18 is a plan view showing an example of the arrangement of the fan blades 51 and 52 in the impeller 40 according to the present embodiment. Also in FIG. 18, the outer shape of the fan blades 51 and 52 (the shape of the root line of the fan blades 51 and 52) is shown as the fan blades 51 and 52. In this embodiment, 10 fan blades 51 and 20 fan blades 52 are arranged at equal intervals, and two fan blades 52 are arranged between adjacent fan blades 51. The difference between this embodiment and the first embodiment is the number of fan blades 51 and 52. In this embodiment as well, the fan blades 51 and 52 have the first fan blade rear end line 51RL and the second fan blade front end. It is arranged so as to overlap the section line 52FL. Further, also in this embodiment, D = 44 mm, L1 = 15.89 mm, L1 / D = 0.36, K1 = 8.91 mm, W = 3.29 mm are set, and the maximum of each fan blade 51.52 is set. The thickness was 1.06 mm in each case. In this embodiment, the fan blade 52 is arranged at a position where d1 = 0.79, d2 = 1.86, and d3 = 1.82, and d1 / D = 0.018, (d1 + d3) /. d2 = 1.41.

<Reference example 1>
FIG. 19 is a plan view showing an example of the arrangement of the fan blades 51 and 52 in the impeller 40 according to this reference example. Also in FIG. 19, the outer shape of the fan blades 51 and 52 (the shape of the root line of the fan blades 51 and 52) is shown as the fan blades 51 and 52. The difference between this reference example and the second embodiment is that in this reference example, one of the fan blades 52 of the second embodiment is shorter than the other. Specifically, the front end portion 52aF of the fan blade 52a is located on the same radius as the rear end portion 51R of the fan blade 51, while the front end portion 52bF of the fan blade 52b is located forward in the rotation direction of the fan blade 51. The fan blades 52a and 52b are formed so as to be located radially outside the rear end portion 51bR of the fan blades 51b. In this reference example, as described above, since the front end portion 52bF of the fan blade 52b is located radially outside the rear end portion 51bR of the fan blade 51b located in the front in the rotation direction, the front end of the fan blade 52b is located. The portion 52bF does not face the fan blade 51b in the rotational direction, but for convenience, in this reference example, the front end portion 52bF of the fan blade 52b and the rear end portion 51R of the fan blade 51b adjacent to the fan blade 52b are provided. The shortest distance between them was d3, d3 = 5.90, and (d1 + d3) / d2 = 3.57. Further, the length K1 of one of the fan blades 52b was set to 5.18 mm, and the length K1 of the other fan blade 52a was set to 8.91 mm as in Examples 1 and 2. For comparison, the other design values were the same as those in Example 2.

Table 1 summarizes the measurement results of the NZ frequency and the noise value at a motor rotation speed of 50,000 rpm in Examples 1 and 2, Comparative Example 1, and Reference Example 1.

As shown in Table 1, according to Examples 1 and 2, it can be seen that the generation of noise can be suppressed and the noise can be reduced as compared with Comparative Example 1 which is a conventional example. Further, from the results shown in Reference Example 1, by providing the above-mentioned fan blades 51 and 52, it is possible to reduce the noise by making the NZ sound difficult to hear, but the front end portion among the plurality of fan blades 52. It can be seen that since the 52F includes the fan blade 52 located radially outside the rear end portion 51R of the fan blade 51, the pressure fluctuation becomes large and the noise value becomes worse than before. As described above, the flow rate of the air flowing into the region VR2 located on the rear end portion 51R side of the fan blade 51 in the region between the fan blades 52 adjacent to each other in the rotation direction is determined by the dimension of d1 + d3. Further, among the regions between the fan blades 52 adjacent to each other in the rotation direction, the flow rate of the air flowing into the region VR3 between the fan blades 52a and the fan blades 52b, which is not located on the rear end portion 51R side of the fan blades 51, is d2. Determined by the dimensions of. As in Reference Example 1, when the front end portion 52bF of the fan blade 52b is located radially outside the rear end portion 51bR of the fan blade 51b located in the front in the rotation direction, the front end portion 52bF of the fan blade 52b is located. The fan blade 51b does not face the fan blade 51b in the rotational direction, and d3 becomes too large. As a result, as described above, (d1 + d3) / d2 = 3.57 and 0.5 <(d1 + d3) / d2 <2.5 are not satisfied, and the flow rate of air flowing into the region corresponding to the region VR2 increases. The flow rate of the air flowing into the region VR3 decreases. As a result, the kinetic energy for suppressing the peeling (slip phenomenon) near the tip on the rear end 52bR side on the negative pressure surface 52bN of the fan blade 52b is reduced, and the air blowing performance and air efficiency are reduced and the noise is increased due to the slip phenomenon. At the same time, the pressure fluctuation at the outer peripheral portion of the impeller 40 becomes large due to the difference in the inflow amount of the air flowing into each region VR2 and VR3, which causes an increase in noise due to the pressure fluctuation.

<Modification example>
FIG. 20 is a plan view showing an example of the arrangement of the fan blades 51 and 52 in the impeller 40 according to the present modification. Also in FIG. 20, the outer shape of the fan blades 51 and 52 (the shape of the root line of the fan blades 51 and 52) is shown as the fan blades 51 and 52. As shown in FIG. 20, only eight fan blades 51 may be formed. In the example shown in FIG. 20, eight fan blades 51 and 16 fan blades 52 are arranged at equal intervals, and two fan blades 52 are arranged between the fan blades 51. Further, in the example shown in FIG. 20, d1 = 0.79 mm, d2 = 2.62 mm, d3 = 3.24 mm, and (d1 + d3) / d2 = 1.54. Further, D = 44 mm, L1 = 15.89 mm, L1 / D = 0.36, K1 = 8.91 mm, W = 3.29 mm, and the maximum thickness of each fan blade 51.52 is 1. It was set to 06 mm. However, the above numerical values are examples, and the present embodiment is not limited to these.

In this modification, unlike the first and second embodiments, d3 is larger than d1 and d2 as in Reference Example 1, but the front end portion 52F of the fan blade 52 and the rear end portion 51R of the fan blade 51 are on the same radius. By being positioned, the rotation direction is between the front end portion 52F of the fan blade 52 located at the frontmost position in the rotation direction of the impeller 40 and the fan blade 51b located at the front in the rotation direction adjacent to the fan blade 52b. A predetermined gap S3 having the shortest distance d3 is formed therein. As a result, as described above, (d1 + d3) / d2 = 1.54 and 0.5 <(d1 + d3) / d2 <2.5 are satisfied, and 0.01 <d1 / D <0.046 is satisfied. The gaps S1 to S3 can be provided. Even when d3 is large in this way, if a certain amount of air flow rate can be secured in the region VR3, the vicinity of the tip on the rear end portion 52bR side of the negative pressure surface 52bN of the fan blade 52b, which is the peeling region in the region VR3. It is possible to suppress the peeling (slip phenomenon) in the impeller 40, and it is possible to suppress the pressure fluctuation in the outer peripheral portion of the impeller 40 due to the difference in the inflow amount of the air flowing into each region VR2 and VR3. Therefore, it goes without saying that the same effects as those of the first and second embodiments can be obtained in the present modification from the above description and the description described in the first and second embodiments.

[Embodiment 2]
As described above, three or more fan blades 52 may be arranged between the virtual lines VL (within the area VR1). The electric blower 20 according to the present embodiment is different from the electric blower 20 according to the first embodiment in that the impeller 40 includes, for example, three fan blades 52 between the virtual lines VL (in the area VR1).

Hereinafter, the impeller 40 according to the present embodiment will be described with reference to examples, and the effects thereof will be described with reference to the reference examples.

<Example 3>
FIG. 21 is a plan view showing an example of the arrangement of the fan blades 51 and 52 in the impeller 40 according to the present embodiment. Also in FIG. 21, the outer shape of the fan blades 51 and 52 (the shape of the root line of the fan blades 51 and 52) is shown as the fan blades 51 and 52. The impeller 40 according to this embodiment is provided with 10 fan blades 51 and 30 fan blades 52. All the fan blades 52 have the same shape, and three fan blades 52 are arranged at equal intervals between the virtual lines VL (within the area VR1). In this embodiment, since three fan blades 52 are arranged between the virtual lines VL, the region located on the rear end 51R side of the fan blades 51 is defined as the region VR2 in the region sandwiched between the adjacent fan blades 52. Assuming that the other region is the region VR3, one region VR2 and two region VR3 exist between the virtual lines VL (inside the region VR1).

In this embodiment, d1 is the impeller 40 of the fan blades 51 (fan blades 51a) located rearward in the rotation direction among the fan blades 51 adjacent to each other in the rotation direction and the fan blades 52 arranged between the virtual lines VL. The shortest distance between the fan blades 52 adjacent to the fan blades 51a, which is located at the rearmost position in the rotation direction, is shown. Further, d2 indicates the shortest distance of the gap between the adjacent fan blades 52 arranged between the virtual lines VL. Further, d3 is the most in the rotation direction among the fan blades 51 (fan blades 51b) located in front of the rotation direction among the fan blades 51 adjacent to each other in the rotation direction and the fan blades 52 arranged between the virtual lines VL. The shortest distance in the rotation direction between the fan blades 52 adjacent to the fan blades 51b located in front of the fan blades 51b is shown.

Further, in the present embodiment, the gap S1 is an impeller of the fan blades 52 arranged between the tip of the fan blade 51a on the rear end portion 51aR side at the lower end of the positive pressure surface 51aP and the virtual line VL facing the tip. A gap between the lower end of the negative pressure surface 52N of the fan blade 52 located at the rearmost position in the rotation direction of 40 is shown. The gap S2 is the tip of the fan blades 52 adjacent to each other between the virtual lines VL on the front end 52F side at the lower end of the positive pressure surface 52P of the fan blade 52 on the rear side in the rotation direction, and the rotation direction facing the tip. The gap between the fan blade 52 on the front side and the lower end of the negative pressure surface 52N is shown. The gap S3 is a fan adjacent to the front end portion 52F of the fan blade 52 located at the frontmost position in the rotation direction of the impeller 40 among the fan blades 52 arranged between the virtual lines VL and the front end portion 52F in the rotation direction. The gap between the blade 51b and the rear end portion 51bR is shown.

In this embodiment, the shortest distance d2 of each gap S2 that is the inlet to each region VR3 is the same, d1 = 0.52, d2 = 0.86, d3 = 0.47, d1 / D = 0. 012, (d1 + d3) / d2 = 1.15.

In this embodiment, W = 2.94 mm was set by changing the value of d1 as described above. However, the values of D, K1 and L1 are set to D = 44 mm, L1 = 15.89 mm, L1 / D = 0.36 and K1 = 8.91 mm as in the above-mentioned Examples 1 and 2 and the like. The maximum thickness of each fan blade 51 and 52 was 1.06 mm.

According to this embodiment, by adopting the above configuration, it is possible to reduce the difference in the inflow amount of the air flowing into each region VR2 and VR3, and it is possible to suppress the pressure fluctuation in the outer peripheral portion of the impeller 40. Will be. Further, the NZ frequency sound can be set as high as 833 × 30 = 25000 Hz, and the NZ sound exceeds the human audible range and cannot be confirmed. Table 2 summarizes the measurement results of the NZ frequency and the noise value at a motor rotation speed of 50,000 rpm in Example 3 and Reference Example 2 described later. As shown in Table 2, in the actual measurement results, it can be seen that the noise value at a motor rotation speed of 50,000 rpm is 73.58 dB, which is improved from the conventional example of Comparative Example 1.

<Reference example 2>
FIG. 22 is a plan view showing an example of the arrangement of the fan blades 51 and 52 in the impeller 40 according to this reference example. Note that also in FIG. 22, the outer shape of the fan blades 51 and 52 (the shape of the root line of the fan blades 51 and 52) is shown as the fan blades 51 and 52. The impeller 40 according to this reference example is provided with eight fan blades 51 and 24 fan blades 52. Three fan blades 52 are arranged between the virtual lines VL. However, in this reference example, of the three fan blades 52 between the virtual lines VL, two are the fan blade 52 located at the frontmost position in the rotation direction of the impeller 40 and the fan blade 52 adjacent to the fan blade 52. The front end 52F of the fan blade 52 is located radially outside the rear end 51R of the fan blade 51, and the remaining one fan blade is located at the rearmost position in the rotation direction among the three fan blades 52. Each fan blade 52 is formed so that the front end portion 52F of the 52 is located on the same radius as the rear end portion 51R of the fan blade 51. Therefore, in this reference example, as in the third embodiment, D = 44 mm, L1 = 15.89 mm, L1 / D = 0.36, and the length K1 of the fan blade located on the same radius as the rear end portion 51R. The length K1 of the two fan blades located radially outside the rear end portion 51R was set to 5.18 mm, while the length K1 was set to 8.91 mm and W = 3.29 mm. The maximum thickness of each fan blade 51 and 52 was 1.06 mm.

Further, in this reference example as well as in reference example 1, as shown in FIG. 22, the front end portion 52F of the fan blade 52 adjacent to the fan blade 51 located in the front in the rotation direction among the fan blades 51 adjacent to each other is the fan. Since the front end portion 52F is located radially outside the rear end portion 51R of the blade 51, the front end portion 52F does not face the fan blade 51 in the rotation direction. Of the adjacent fan blades 51, the fan blade 51 (fan blade 51b) located in front of the rotation direction and the fan blade 52 arranged between the virtual lines VL, the fan blade 51b located in the frontmost position in the rotation direction. The shortest distance of the gap in the rotation direction between the fan blades 52 adjacent to the fan blade 52 is set to d3. In this reference example, d1 = 0.79, d2 = 1.48, d3 = 4.98, d1 / D = 0.018, (d1 + d3) / d2 = 3.90, and design values other than the above-mentioned numerical values. As shown in Table 2, the noise value when the motor rotation speed was 50,000 rpm was 77.32 dB, which was worse than the conventional one. From the results shown in Table 2, even when three or more fan blades 52 are provided between the virtual lines VL, by providing the above-mentioned fan blades 51 and 52, it is possible to reduce the noise by making the NZ sound difficult to hear. Although it is possible to plan, the pressure fluctuation is caused by the fact that the plurality of fan blades 52 include the fan blade 52 whose front end portion 52F is located radially outside the rear end portion 51R of the fan blade 51. It can be seen that the noise level becomes larger and the noise level becomes worse than before.

[Embodiment 3]
FIG. 23 is a plan view showing an example of the arrangement of the fan blades 51 and 52 in the impeller 40 according to the present embodiment. Also in FIG. 23, the outer shape of the fan blades 51 and 52 (the shape of the root line of the fan blades 51 and 52) is shown as the fan blades 51 and 52. The impeller 40 according to the present embodiment is different from the impeller 40 described in each of the examples in the first and second embodiments in the following points. That is, in the impeller 40 according to the present embodiment, as shown in FIG. 23, the front end portion 52F of the fan blade 52 is arranged so as to be located radially inside the rear end portion 51R of the fan blade 51. .. Therefore, the circular first fan blade rear end line 51RL connecting the rear end portions 51R of each fan blade 51 is the circular second fan blade front end portion line 52FL connecting the front end portions 52F of each fan blade 52. It is located on the outside.

According to the present embodiment, the front end portion 52F of the fan blade 52 is located radially inside the rear end portion 51R of the fan blade 51, whereby the fan blade 52b (in other words, arranged between the virtual lines VL) is arranged. Of the fan blades 52, the fan blade 52) located at the frontmost position in the rotation direction of the impeller 40 and the fan blade 51b adjacent to the fan blade 52b and located at the front in the rotation direction are located in the rotation direction. , A predetermined gap S3 can be provided.

In this embodiment, the definitions of d1, d2, S1 and S2 are the same as those of the first and second embodiments. Further, also in the present embodiment, as in the first and second embodiments, the d3 is between the fan blade 51 (fan blade 51b) located in front of the rotation direction among the fan blades 51 adjacent to each other in the rotation direction and the virtual line VL. Indicates the shortest distance in the rotation direction between the fan blades 52 (inside VL1) located in the frontmost position in the rotation direction and the fan blades 52 (fan blades 52b) adjacent to the fan blades 51b. .. The d3 is when a circle having a diameter in the rotation direction is drawn between the fan blades 52b and the fan blades 51b adjacent to the fan blades 52b in the rotation direction and facing each other in the rotation direction. , Indicated by the diameter (φ) of the smallest circle.

However, when the front end portion 52bF of the fan blade 52b is located radially inside the rear end portion 51bR of the fan blade 51b located in front of the rotation direction, the fan blade 52b is, for example, the length of the fan blade 52b. Due to the length L1 of K1 and the fan blade 51b, the fan blade 51b faces the rear end portion 51bR or the negative pressure surface 51bN in the rotation direction.

Therefore, in the present embodiment, the gap S3 is the front end portion 52bF of the fan blade 52b located at the frontmost position in the rotation direction among the fan blades 52 arranged between the virtual lines VL, and the fan blades adjacent to each other in the rotation direction. Of 51, between the rear end 51bR of the fan blade 51b located in front of the rotation direction, or the tip of the fan blade 52b on the front end 52bF side at the lower end of the positive pressure surface 52bP, facing the tip. The gap between the fan blade 51b and the lower end of the negative pressure surface 51bN is shown, and d3 shows the distance of the gap S3.

The impeller 40 shown in FIG. 23 corresponds to the first embodiment of the first embodiment except that the front end portion 52F of the fan blade 52 is located slightly inside the rear end portion 51R of the fan blade 51 in the radial direction. Same as the impeller 40, d3 shows a gap between the front end 52bF of the fan blade 52b and the rear end 51bR of the fan blade 51b, as in the first embodiment.

As described above, also in the present embodiment, as in the first and second embodiments, the fan blade 52 located at the frontmost position in the rotation direction of the impeller 40 among the fan blades 52 arranged between the virtual lines VL and the fan. A predetermined gap S3 is formed in the rotation direction between the fan blade 51 and the fan blade 51 adjacent to the blade 52 and located in front of the rotation direction. Therefore, even when the front end portion 52F of the fan blade 52 is located radially inside the rear end portion 51R of the fan blade 51 as in the present embodiment, the front end portion 52F of the fan blade 52 and the rear of the fan blade 51 are located. Air flows into the region VR2 from the negative pressure surface 51N side of the fan blade 51 through the gap S3, as in the case where the end portion 51R is located on the same radius. Further, even when the front end portion 52F of the fan blade 52 is located radially inside the rear end portion 51R of the fan blade 51 as in the present embodiment, the rear end portion 51aR at the lower end of the positive pressure surface 51aP of the fan blade 51a A predetermined gap S1 is formed between the tip on the side and the lower end of the negative pressure surface 52aN of the fan blade 52a facing the tip. Thereby, also in this case, the air having higher kinetic energy flowing along the positive pressure surface 51P of the fan blade 51 can be effectively poured into the rear end portion 52R of the fan blade 52 from the gap S1. Therefore, also in the present embodiment, as in the first embodiment, the separation of the airflow (slip phenomenon) in the separation region can be suppressed, and the deterioration of the ventilation performance and the ventilation efficiency and the noise due to the slip phenomenon can be suppressed. Can be done. Further, also in the present embodiment, the flow rate (air volume) of the air in each region VR2 / VR3 is adjusted from d1 to d3 (in other words, the size of the gaps S1 to S3) to adjust the flow rate (air volume) of the air flowing into each region VR2 / VR3. It can be adjusted by adjusting the inflow rate.

In the impeller 40 shown in FIG. 23, 11 fan blades 51 and 22 fan blades 52 are arranged at equal intervals, and two fan blades 52 are arranged between adjacent fan blades 51. Further, D = 44 mm, L1 = 15.89 mm, L1 / D = 0.36, K1 = 9.47 mm, W = 3.65 mm, d1 = 0.79, d2 = 1.58 mm, d3 = 0.81 mm, d1 / D = 0.018, (d1 + d3) / d2 = 1.01, and the maximum thickness of each fan blade 51 and 52 is 1.06 mm. However, the above numerical values are examples, and the present embodiment is not limited to these.

The impeller 40 shown in FIG. 23 has the same number of fan blades 51 and 52 as the impeller 40 shown in the first embodiment, and K1 / D is within the range of 0.1 <K1 / D ≦ 0.25. , W / D is within the range of 0.04 ≦ W / D ≦ 0.11. Therefore, it goes without saying that according to the impeller 40 shown in FIG. 23, the same effect as that of the impeller 40 according to the first and second embodiments can be obtained from the description described in the first and second embodiments.

[Embodiment 4]
FIG. 24 is a plan view showing an example of the arrangement of the fan blades 51 and 52 in the impeller 40 according to the present embodiment. Also in FIG. 24, the outer shape of the fan blades 51 and 52 (the shape of the root line of the fan blades 51 and 52) is shown as the fan blades 51 and 52. As shown in FIG. 24, the impeller 40 according to the present embodiment has a different shape of some fan blades 52 among the plurality of fan blades 52.

In the example shown in FIG. 24, eight fan blades 51 and 16 fan blades 52 are arranged at equal intervals, and fan blades 52a and 52b having different lengths are arranged between the fan blades 51. .. In the example shown in FIG. 24, the fan blade 52b is longer than the fan blade 52a, and the front end portion 52bF of the fan blade 52b is located radially inside the rear end portion 51R of the fan blade 51, while the front end portion of the fan blade 52a. 52aF is located on the same radius as the rear end portion 51R of the fan blade 51.

In the example shown in FIG. 24, the fan blade 52b is formed between the fan blade 52b and the fan blade 51b by making the length of the fan blade 52b longer than that of the fan blade 52b shown in FIG. 5 in the first embodiment of the first embodiment. As a gap (gap S3) in the rotation direction of the impeller 40, the tip of the fan blade 52b on the front end 52bF side at the lower end of the positive pressure surface 52bP and the lower end of the negative pressure surface 51bN of the fan blade 51b facing the tip. A gap can be provided between them. In the example shown in FIG. 24, d1 = 0.79 mm, d2 = 2.62 mm, d3 = 1.44 mm, and (d1 + d3) / d2 = 0.85. Further, D = 44 mm, L1 = 15.89 mm, L1 / D = 0.36, and the maximum thickness of each fan blade 51 and 52 was 1.06 mm. Further, the length K1 of the fan blade 52b was 11.34 mm, the length K1 of the fan blade 52a was 8.91 mm as in Example 1, and W = 3.29 mm. However, the above numerical values are examples, and the present embodiment is not limited to these. From the explanations described in the first and second embodiments, it goes without saying that the same effects as those of the first to third embodiments can be obtained in the present embodiment as well.

Further, in the present embodiment, the case where the fan blade 52b is made longer than the fan blade 52b shown in FIG. 5 among the fan blades 52a and 52b has been described as an example, but both of the fan blades 52a and 52b are shown in FIG. Needless to say, it may be longer than the fan blade 52b shown in 1.

[Embodiment 5]
In the first embodiment, the case where the electric blower 20 provided with the impeller 40 is incorporated in the handy type (or stick type) cordless electric vacuum cleaner 100 shown in FIG. 1 has been described as an example. However, the electric blower 20 according to each of the above-described embodiments can be applied to a canister type electric vacuum cleaner or a blower such as a hair dryer.

The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims, and the embodiments obtained by appropriately combining the technical means disclosed in the different embodiments. Is also included in the technical scope of the present invention. Further, by combining the technical means disclosed in each embodiment, new technical features can be formed.

20 Electric blower 38 Motor 38T Rotating shaft 40 Impeller 44 Disk 44a Outer peripheral end 51, 51a, 51b Fan blade (first fan blade)
52, 52a, 52b fan blade (second fan blade)
51F, 51aF, 51bF, 52F, 52aF, 52bF Front end 51R, 51aR, 51bR, 52R, 52aR, 52bR Rear end 51N, 51aN, 51bN, 52N, 52aN, 52bN Negative pressure surface 51P, 51aP, 51bP, 52P, 52aP, 52bP Positive pressure surface 100 Electric vacuum cleaner S1, S2, S3 Gap VL Virtual line

Claims (5)

A motor with a rotating shaft and
With an impeller attached to the above rotating shaft,
The impeller comprises a plurality of first fan blades and a plurality of second fan blades.
Each of the plurality of first fan blades has a first tip portion located forward in the rotation direction of the impeller and a second tip portion located rearward in the rotation direction in the longitudinal direction of each of the plurality of first fan blades. The portion between the first tip portion and the second tip portion extends so as to warp toward the front side in the rotational direction, and the second tip portion extends from the outermost circumference of the impeller. Located on the inside in the radial direction,
The second fan blade is between the virtual lines extending from the first tip of each of the first fan blades adjacent to each other in the rotation direction to the outermost periphery of the impeller along the extending direction of each first fan blade. There are multiple locations,
Each of the plurality of second fan blades has a third tip portion located forward in the rotational direction and a fourth tip portion located rearward in the rotational direction in the longitudinal direction thereof in a plan view. The fourth tip is located on the outermost circumference of the impeller, and the third tip is located on the same radius as the second tip or radially inside the second tip. Located in
Of the first fan blades adjacent to each other in the rotation direction, the first fan blade located behind the rotation direction and the plurality of second fan blades arranged between the virtual lines are the rearmost in the rotation direction. The shortest distance between the second fan blades located is d1, and one of the second fan blades adjacent to each other arranged between the virtual lines is the second fan blade and the other second fan blade. The shortest distance between the two fan blades is d2, and among the second fan blades arranged between the virtual lines, the second fan blade located at the frontmost position in the rotation direction and the rotation facing the rotation direction. An electric blower characterized in that 0.5 <(d1 + d3) / d2 <2.5, where d3 is the shortest distance between the first fan blades located in front of the direction . The electric blower according to claim 1 , wherein the diameter of the impeller is 0.01 <d1 / D <0.046. A motor with a rotating shaft and
With an impeller attached to the above rotating shaft,
The impeller comprises a plurality of first fan blades and a plurality of second fan blades.
Each of the plurality of first fan blades has a first tip portion located forward in the rotation direction of the impeller and a second tip portion located rearward in the rotation direction in the longitudinal direction of each of the plurality of first fan blades. The portion between the first tip portion and the second tip portion extends so as to warp toward the front side in the rotational direction, and the second tip portion extends from the outermost circumference of the impeller. Located on the inside in the radial direction,
The second fan blade is between the virtual lines extending from the first tip of each of the first fan blades adjacent to each other in the rotation direction to the outermost periphery of the impeller along the extending direction of each first fan blade. There are multiple locations,
Each of the plurality of second fan blades has a third tip portion located forward in the rotational direction and a fourth tip portion located rearward in the rotational direction in the longitudinal direction thereof in a plan view. The fourth tip is located on the outermost circumference of the impeller, and the third tip is located on the same radius as the second tip or radially inside the second tip. Located in
Assuming that the diameter of the impeller is D and the length of the straight line connecting the first tip portion and the second tip portion of the first fan blade is L1, 0.15 ≦ L1 / D ≦ 0.4. Characterized electric blower. A motor with a rotating shaft and
With an impeller attached to the above rotating shaft,
The impeller comprises a plurality of first fan blades and a plurality of second fan blades.
Each of the plurality of first fan blades has a first tip portion located forward in the rotation direction of the impeller and a second tip portion located rearward in the rotation direction in the longitudinal direction of each of the plurality of first fan blades. The portion between the first tip portion and the second tip portion extends so as to warp toward the front side in the rotational direction, and the second tip portion extends from the outermost circumference of the impeller. Located on the inside in the radial direction,
The second fan blade is between the virtual lines extending from the first tip of each of the first fan blades adjacent to each other in the rotation direction to the outermost periphery of the impeller along the extending direction of each first fan blade. There are multiple locations,
Each of the plurality of second fan blades has a third tip portion located forward in the rotational direction and a fourth tip portion located rearward in the rotational direction in the longitudinal direction thereof in a plan view. The fourth tip is located on the outermost circumference of the impeller, and the third tip is located on the same radius as the second tip or radially inside the second tip. Located in
Assuming that the total number of the second fan blades is z and the rotation speed of the motor is n (s ^-1 ), 8000 ≦ n × z, n ≧ 500, and z ≦ 33. Electric blower. An electric vacuum cleaner comprising the electric blower according to any one of claims 1 to 4 .

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