JP2019007362A - Electric blower - Google Patents

Abstract

To provide an electric blower that achieves both reduction of the size by applying an axial flow blower and improvement of the efficiency by suppressing blade end vortexes.SOLUTION: An electric blower comprises an electric motor, an axial flow fan coaxial with the rotation shaft of the electric motor, and a fan casing that covers the axial flow blower and has a suction port. The rotor blade of the axial flow blower comprises a plurality of blades and a ring abutting at least parts of the ends of the blades. The fan casing has a stepped portion in the inner cylinder surface. The inner diameter of the fun casing is larger on the electric motor side as compared with that on the suction port side. At least a part of the ring is located closer to the electric motor side than the stepped portion of the fan casing. The outer diameter of the ring is larger than the inner diameter on the suction port side of the fan casing and is smaller than the inner diameter on the electric motor side of the fan casing.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an electric fan equipped with an axial fan.

As an electric blower mounted with an axial blower, there is one disclosed in Japanese Patent No. 4785908 (Patent Document 1). In Patent Document 1, a floor brush is attached to the tip of a cylindrical case, and a dust collection chamber, an electric blower, and a drive circuit chamber are arranged in that order from the tip side, and the drive circuit chamber is located. A plurality of exhaust ports are provided on the rear end side of the case, and the electric blower is constituted by an axial fan and a brushless DC motor.

Japanese Patent No. 4785908

  In some electric appliances, it is required to reduce the size and increase the efficiency of the electric blower. For example, since a vacuum cleaner is required to be easy to use and have a strong suction force, downsizing and high efficiency are also required for an electric blower mounted on the vacuum cleaner.

  The electric blower mounted on the conventional vacuum cleaner is generally composed of a centrifugal blower and an electric motor. Since the centrifugal blower discharges air sucked from the rotation axis direction of the electric motor in the outer diameter direction, the outer diameter of the blower tends to increase. On the other hand, since the axial blower discharges air sucked from the rotation axis direction of the electric motor in the rotation axis direction as it is, the outer diameter of the blower can be reduced.

  According to Patent Document 1, since the electric blower is composed of an axial fan and a brushless DC motor, the stick shape does not swell and can be reduced in size and weight, is easy to use, and has an effect of reducing operation labor. Have been described. However, the axial flow fan has a problem that a blade tip vortex is generated at the end of the moving blade, and the energy efficiency of the blower is reduced. The larger the blade tip clearance ratio (L / S) expressed by the ratio of the blade tip clearance L, which is the gap between the moving blade and the fan casing, and the blade span S, which is the width of the moving blade, the greater the influence of the blade tip vortex. The energy efficiency of is reduced. In a small axial fan, since the blade span S is small, the blade tip clearance ratio tends to increase, and it is difficult to achieve both size reduction and high efficiency.

  An object of the present invention is to solve the above-described problems, and to provide an electric blower that achieves both miniaturization by application of an axial blower and high efficiency by suppressing a blade simple vortex.

  In order to solve the above-described problems, one of the representative aspects of the present invention includes an electric motor, an electric fan that is coaxial with the rotating shaft of the electric motor, and a fan casing that covers the axial fan and has a suction port. In the blower, the rotor blade of the axial flow fan includes a plurality of blades and a ring that abuts at least a part of the end of the blade, and the fan casing has a step portion on the inner cylindrical surface. The inner diameter is larger on the motor side than the suction port side, and at least a part of the ring is located on the motor side with respect to the step portion of the fan casing, and the outer diameter of the ring is larger than the inner diameter on the suction port side of the fan casing, This is achieved by being characterized by being smaller than the inner diameter of the fan casing on the motor side.

ADVANTAGE OF THE INVENTION According to this invention, the electric blower which made compatible the size reduction by application of an axial flow fan, and the high efficiency by suppressing a blade tip vortex can be provided.
Problems, configurations, and effects other than those described above will be clarified by the following description of embodiments.

It is an external appearance perspective view at the time of using the vacuum cleaner which concerns on this invention as a stick type. It is a side view at the time of using the vacuum cleaner which concerns on this invention as a handy type. It is a longitudinal section of the electric blower in the 1st example of an embodiment of the present invention. (A) is an external appearance perspective view of the moving blade of the electric blower in the 1st Example of this invention, (b) is a front view of a moving blade. FIG. 5 is a schematic diagram of blade tip vortices generated when the moving blade shown in FIG. 4 is not provided with a ring. 1 is an embodiment of a ring that abuts at least a part of the end of the wing, in which (a) is an example in which the ring abuts against the end of the wing from the leading edge to the middle of the wing, and (b) is an intermediate of the wing. It is an example which a ring contact | abuts to a rear edge from a part. It is a cross-sectional enlarged view of a moving blade and a case casing in the second embodiment of the present invention. It is a cross-sectional enlarged view of a moving blade and a fan casing in the case of having a seal member in the second embodiment of the present invention. It is the cross-sectional enlarged view of a moving blade and a fan casing in the case of having the sealing member in the second embodiment of the present invention, and is an example in which the plate thickness of the front edge 42a of the ring is formed thinner from the outer periphery toward the inner periphery. is there.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, exemplary embodiments for carrying out the invention will be described with reference to the drawings. Here, a vacuum cleaner is mentioned as an example of an electric appliance, and one Example of this invention regarding an electric blower is described.

(First embodiment)
First, with reference to FIG. 1 and FIG. 2, a vacuum cleaner will be described as an application example of an electric blower. FIG. 1 is an external perspective view when the vacuum cleaner equipped with the present invention is used as a stick type, and FIG. 2 is a side view when the vacuum cleaner equipped with the present invention is used as a handy type.

  The electric vacuum cleaner 100 includes a vacuum cleaner body 1, a dust case 2, and a mouthpiece 3. In addition, in FIG. 1, when the suction body 3 is attached to the vacuum cleaner 100, FIG. 2 shows the case where the gap nozzle 3a is attached instead of the suction body 3, and these are shown in accordance with the use application. It can be used by switching appropriately.

  The vacuum cleaner main body 1 includes a telescopic pipe 4, a pipe case 5, a handle 6, a storage battery case 7, and a motor case 8. The storage battery case 7 includes a storage battery (not shown), and the motor case unit 8 includes An electric blower 10 (see FIG. 3) and a circuit (not shown) for driving the electric blower 10 are included, and the pipe case 5 includes an expandable pipe 4.

  The extendable pipe 4 is supported in the pipe case 5 so as to be extendable and contractable, and the extendable pipe 4 can be expanded and contracted by pressing a push button 9 provided on the side surface of the cleaner body 1.

  The handle 6 is a portion that is gripped by a user's hand, and is rotatably supported at the tip of the telescopic pipe 4. Further, the handle 6 has a grip portion 6a that becomes a portion gripped by a user when used as a stick type, and a grip portion 6b that is gripped by a user when used as a handy type. The handle 6 includes operation buttons 11a and 11b. The operation button 11a is operated when used as a stick type, and is provided on the outer surface of the grip portion 6a. The operation button 11b is operated when used as a handy type, and is provided on the outer surface of the grip portion 6b.

  When the electric blower 10 is operated by operating the operation button 11a or 11b, a suction air flow is generated. The air containing dust is sucked from the mouthpiece 3 or the gap nozzle 3 a and reaches the dust case 2 through the connecting portion 12. Air containing dust that has reached the dust case 2 is separated in the dust case 2. The air from which the dust has been separated reaches the electric blower 10 (see FIG. 3), cools a circuit (not shown) downstream of the electric blower 10, and then discharges it to the outside of the cleaner body 1.

  Next, the electric blower and the moving blade in the first embodiment of the present invention will be described with reference to FIGS. 3 and 4. FIG. 3 is a longitudinal sectional view of the electric blower. FIG. 4A is an external perspective view of a moving blade of an electric blower, and FIG. 4B is a front view of the moving blade.

  The electric blower 10 includes an axial blower 20, a fan casing 21, an electric motor 22, and a housing 23.

  The electric motor 22 includes a shaft 24 housed in a housing 23, a rotor core 25 integrated with the shaft 24, and a stator 26 fixed to the housing 23.

  The rotor core 25 is formed at the end of the shaft 24 opposite to the end where the rotor blade 30 is fixed, and is made of a rare earth bond magnet. A rare earth bond magnet is made by mixing a rare earth magnetic powder and an organic binder. As the rare earth bond magnet, for example, a samarium iron nitrogen magnet, a neodymium magnet, or the like can be used. The stator 26 includes a stator core (not shown) and a metal wire (not shown) wound around the stator core. A bearing 27 is provided between the moving blade 30 and the rotor core 25, and the shaft 24 is rotatably supported.

  The axial blower 20 includes a moving blade 30 and a stationary blade 31. The axial blower 20 targeted by the present invention has a blower outer diameter of φ50 mm or less and a maximum rotational speed of 80,000 revolutions per minute or more, and realizes a small axial blower with a high rotational speed.

  The moving blade 30 is made of a thermoplastic resin, and is configured by integrally forming eight blades 40, a boss 41, and a ring 42. In the present embodiment, the moving blade 30 is fastened to the shaft 24 by fixing two places with the screws 32 from the side, but this is not restrictive. A screw may be provided at the end of the shaft 24, and the moving blade 30 may be fastened using a fixing nut. The ring 42 is provided so as to surround the entire outer periphery of the wing 40, and all ends of the wing 40 are in contact with the inner periphery of the ring 42. In this embodiment, the wing 40, the boss 41, and the ring 42 are integrally formed by injection molding using two molds. When viewed from the upstream side in parallel with the rotation axis of the electric motor 22, the adjacent moving blades 30 have overlapping projection areas. Therefore, in the injection molding, the resin is injected into a two-part mold, and when the resin is solidified, one of the two molds is separated while being rotated, thereby removing the moving blade 30. In the present embodiment, the wing 40, the boss 41, and the annular ring 42 are integrally formed. This is particularly preferable when used at a high speed rotation because the strength can be secured. is not. The ring 42 may be manufactured as a separate piece and bonded by ultrasonic welding or the like. Further, the moving blade 30 is not limited to a thermoplastic resin, and may be made of a metal such as aluminum.

  The fan casing 21 has a step portion 21b on the inner cylindrical surface 21a, and the inner diameter b of the fan casing 21 is larger on the motor 22 side inner diameter b than on the suction port 34 side inner diameter a. The ring 42 is located downstream of the step portion 21b, that is, closer to the electric motor 22 than the step portion 21b. The blade tip diameter c is equal to the inner diameter a on the suction port 34 side. The ring outer diameter d is larger than the suction port 34 side inner diameter a and smaller than the motor 22 side inner diameter b.

  Next, the flow of air in the electric blower 10 will be described. When the electric motor 22 is driven and the moving blade 30 rotates about the shaft 24 as a rotation axis, air flows from the suction port 34 and flows into the moving blade 30. The air flowing into the moving blade 30 is increased in pressure and increased in speed and reaches the stationary blade 31. The air flowing into the stationary blade 31 is evacuated from the exhaust port 35 to the outside after the kinetic energy is converted into pressure energy and the pressure is increased. The axial blower 20 discharges the air sucked from the rotation axis direction of the electric motor 22 in the rotation axis direction as it is. Therefore, the outer diameter of the blower can be reduced as compared with a centrifugal blower in which air sucked from the rotation axis direction of the electric motor 22 is discharged in the outer diameter direction and a stationary blade is disposed on the outer diameter side of the moving blade.

  In the present embodiment, the single-stage axial blower 20 is applied. However, the present invention is not limited to this, and the axial blower 20 may have two or more stages. By making the axial blower 20 into two or more stages, the diameter can be further reduced under the same output conditions. Alternatively, the output can be increased under the same blower outer diameter condition.

Next, the specific speed to which the electric blower is applied will be described. The specific speed N _s is expressed as N _s = N × Q ^0.5 / H ^0.75 using the rotational speed N, the air volume Q, and the total head H. Generally, the form of the blower is organized using a specific speed N _s, axial blower can obtain high efficiency at higher specific speeds band than the centrifugal blower. Since the specific speed N _s in accordance with increase in the rotational speed N is increased, in the present embodiment to reduce the size of the axial flow fan by a high rotational speed, it is possible to configure the blower at a high specific speed, high efficiency Can be obtained.

  For example, at a blower outer diameter of 40 mm and 15,000 revolutions per minute, a static pressure increase of 11,000 Pa can be obtained at a design air volume of 0.9 m / min. Therefore, even when a high static pressure is required like a vacuum cleaner, a vacuum cleaner with a strong suction force can be realized.

  The ring 42 is provided so as to surround the entire outer periphery of the wing 40. The ring 42 suppresses the blade tip vortex 60 (see FIG. 5) that occurs at the end 40a of the blade 40 and causes energy loss. FIG. 5 shows a schematic diagram of blade tip vortices generated when no ring is provided. As shown in FIG. 5, when the ring 42 is not provided, the blade tip vortex 60 is generated in the blade tip gap L that is the gap between the end 40a of the blade 40 and the fan casing 21, which causes energy loss. . As the blade tip clearance ratio (L / S) expressed by the ratio between the blade tip clearance L and the blade span S is larger, the influence of the loss due to the blade tip vortex 60 is greater, and the energy efficiency of the blower is reduced. Considering the extension of the blade 40 due to centrifugal force and the swirling of the rotating system, the blade end gap L is required to be about 1 mm regardless of the size of the axial flow fan 20. In the small axial flow fan 20 having a blower outer diameter of φ50 mm or less as in the present embodiment, the blade span S is small, so the blade tip clearance ratio (L / S) is increased and the blade tip vortex 60 is caused. The loss is particularly large. Therefore, by providing the ring 42, it is possible to obtain the highly efficient electric blower 10.

  The ring 42 is provided so as to surround the entire outer periphery of the blade 40, and all end portions 40 a of the blade 40 are in contact with the inner periphery of the ring 42, but this is not restrictive. FIG. 6 shows an example of a ring that abuts at least a part of the end of the wing. FIG. 6A shows an example in which the ring abuts on the end of the blade from the leading edge to the middle portion of the blade, and FIG. 6B shows an example in which the ring abuts on the trailing edge from the middle portion of the blade. As shown in FIG. 6, as long as the ring 42 abuts at least a part of the end 40 a of the blade 40, the effect of suppressing the blade tip vortex 60 can be obtained, and the highly efficient electric blower 10 is obtained. .

  The fan casing 21 has a step portion 21b on the inner cylindrical surface 21a, and the inner diameter b of the fan casing 21 is larger on the motor 22 side inner diameter b than on the suction port 34 side inner diameter a. The ring 42 is located downstream of the step portion 21a, that is, closer to the electric motor 22 than the step portion 21b. The blade tip diameter c is equal to the inner diameter a on the suction port 34 side. The outer diameter d of the ring is larger than the inner diameter a on the suction port 34 side and smaller than the inner diameter b on the electric motor 22 side, thereby suppressing a circulation flow that causes energy loss. The circulating flow is an air flow in which the flow discharged from the blade outlet 43 passes through the gap 44 formed between the fan casing 21 and the ring 42 and re-enters the blade inlet 45. In particular, when a high static pressure is required as in a vacuum cleaner, the static pressure difference between the moving blade inlet 45 and the moving blade outlet 43 is large. Increases and energy loss increases. In the present embodiment, the ring outer diameter d is larger than the suction port 34 side inner diameter a and smaller than the motor 22 side inner diameter b, thereby increasing the ventilation resistance in the gap 44 and suppressing the circulation flow. Can do. Therefore, the highly efficient electric blower 10 can be obtained.

  In the present embodiment, the suction port 34 side inner diameter a and the blade tip diameter c are equal, and in the flow path connecting the suction port 34, the blade inlet 45, and the blade outlet 43, Since there is no level difference, energy loss at the moving blade inlet 45 can be reduced and the more efficient electric blower 10 can be obtained, but this is not restrictive. If the ring outer diameter d, the suction port 34 inner diameter a, and the motor 22 inner diameter b satisfy the relationship of a <d <b, the ventilation resistance in the gap 44 increases, and the effect of suppressing the circulation flow can be obtained. Therefore, a highly efficient electric blower 10 is obtained.

  From the above, it is possible to provide an electric blower equipped with an axial blower that achieves both miniaturization and high efficiency.

  By mounting the electric blower 10 of the present embodiment, the vacuum cleaner 100 having a strong suction force, a small size, and an easy-to-use can be obtained. In particular, when the electric blower 10 is mounted on the rechargeable cordless stick type shown in this embodiment, a stick-shaped vacuum cleaner having a small diameter can be realized, and the usability can be improved.

  In addition, when the electric blower 10 is mounted on a rechargeable cordless stick type or an autonomous traveling type cleaner, the efficiency of the electric blower 10 is improved, so that the input is reduced when operating with the same output. Therefore, it is possible to operate for a long time with low power consumption. Furthermore, since the number of times of charging of the battery is reduced by suppressing power consumption, the voltage drop of the battery due to repeated charging can be delayed.

  The electric blower 10 according to the present embodiment is not limited to an electric vacuum cleaner, but can be applied to an electric appliance such as a hair dryer, a hand dryer, or a blower for blowing off dust and fallen leaves. By applying the electric blower 10 of the present embodiment, it is possible to realize a hair dryer, hand dryer, or blower that has a large air volume, is small, and is easy to use.

  In addition, hair dryers, hand dryers, and blowers that require a large air volume operate at a higher specific speed than a vacuum cleaner. Therefore, a highly efficient hair dryer, hand dryer, or blower can be realized by applying the electric blower 10 of the present embodiment equipped with an axial blower that can obtain high efficiency at a high specific speed. .

(Second Embodiment)
A second embodiment will be described with reference to FIG. FIG. 7 is an enlarged cross-sectional view of the rotor blade and the fan casing in the second embodiment of the present invention. Since the basic configuration is the same as that of the first embodiment, the same elements are denoted by the same reference numerals and description thereof is omitted.

  The fan casing 21 has a recess 21c in the step portion 21b. Most of the ring 42 is located downstream of the stepped portion 21b, that is, closer to the electric motor 22 (see FIG. 3) than the stepped portion 21b, but the front edge 42a is located closer to the suction port 34 than the stepped portion 21b. The space 21d is formed by the step portion 21b and the recess 21c. Since the front edge 42a enters the space 21d formed by the stepped portion 21b and the recessed portion 21c, the ventilation resistance in the gap 44 becomes larger and the circulation flow is better suppressed. Therefore, it is possible to obtain a more efficient electric blower 10.

  Further, since the thickness of the tip of the leading edge 42a is thin, the leading edge 42a enters the space 21d formed by the step portion 21b and the recess 21c, and the blade tip diameter c and the suction port 34 side inner diameter a. It is possible to achieve a configuration with equal. Therefore, it is possible to obtain a more efficient electric blower 10 by reducing the energy loss at the moving blade inlet 45 while suppressing the circulation flow that causes energy loss.

  Next, FIG. 8 shows an enlarged cross-sectional view of the moving blade and the fan casing when the sealing member is provided. As shown in FIG. 8, the recess 21c may be filled with a seal member 50. The seal member 50 is more preferably a low friction material such as oil clay, silicon rubber, or PTFE (polytetrafluoroethylene). The seal member 50 substantially comes into contact with the ring leading edge 42a and better suppresses the circulation flow that causes energy loss. Therefore, it is possible to obtain a more efficient electric blower 10.

  Since the seal member 50 is filled in the concave portion 21c, the seal member 50 can be prevented from falling off, and further, the obstruction of the air flow by the dropped seal member 50 can be prevented. Therefore, it is possible to obtain a more efficient electric blower 10.

  Further, the front edge 42a has a thin plate at the tip. Therefore, the contact area between the seal member 50 and the front edge 42a is small, sliding friction loss can be reduced, and the highly efficient electric blower 10 can be obtained. However, the shape of the front edge 42a is not limited to this. Absent.

  As shown in FIG. 9, the plate thickness of the front edge 42a of the ring 42 may be formed thinner from the outer periphery toward the inner periphery. In this case, since the front edge 42a and the seal member 50 are substantially in contact with each other on the inner diameter side, the speed of the front edge 42a that is the contact portion is small, and the sliding friction loss can be further reduced.

DESCRIPTION OF SYMBOLS 1 Vacuum cleaner body 2 Dust case 3 Mouthpiece 4 Telescopic pipe 5 Pipe case 6 Handle 7 Storage battery case 8 Motor case 9 Push button 10 Electric blower 12 Connection part 20 Axial flow blower 21 Fan casing 22 Electric motor 23 Housing 24 Shaft 25 Rotor core 26 Stator 27 Bearing 30 Moving blade 31 Stator blade 34 Suction port 35 Exhaust port 40 Blade 41 Boss 42 Ring 43 Moving blade outlet 44 Clearance 45 Moving blade inlet 50 Seal member 60 Blade tip vortex 100 Electric vacuum cleaner

Claims (4)

In an electric blower comprising an electric motor, an axial flow fan coaxial with the rotating shaft of the electric motor, and a fan casing that covers the axial flow fan and has a suction port,
The rotor blade of the axial flow fan includes a plurality of blades and a ring that comes into contact with at least a part of the end portion of the blade,
The fan casing has a step portion on an inner cylinder surface, and the inner diameter of the fan casing is larger on the motor side than on the suction port side,
At least a part of the ring is located closer to the motor than the stepped portion of the fan casing, and the outer diameter of the ring is larger than the inner diameter of the fan casing on the inlet side, and the motor side of the fan casing An electric blower characterized by being smaller than the inner diameter of the fan.   2. The electric blower according to claim 1, wherein the stepped portion of the fan casing has a recess, and the front edge of the ring is located closer to the suction port than the stepped portion.   The electric blower according to claim 2, wherein the recess is filled with a seal member, and the seal member substantially contacts the front edge of the ring.   The electric blower according to any one of claims 1 to 3, wherein the axial blower has two or more stages.

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