JP7233949B2 - Blower - Google Patents

Description

The present invention relates to blowers, and more particularly to multi-stage centrifugal blowers.

2. Description of the Related Art A blower capable of blowing off dust and the like by discharging air from a nozzle is known. Such a blower is generally called an air duster. For example, Patent Literature 1 discloses an air duster that has an air compression section that includes a five-stage centrifugal fan and that is capable of injecting compressed air generated by this air compression section.

JP 2011-117442 A

In the air duster of Patent Document 1, each stage of the air compression section is configured by non-contact fitting rotor blades fixed to an output shaft of a motor inside stationary blades fixed to a housing. The stator vanes are provided on the surface facing the rotor blades, and lead-out fins are provided on the opposite surface to guide the air sent out by the rotor blades to the opposite surface. There is provided a vane wheel that feeds in. Therefore, the configuration of the air duster is complicated.

SUMMARY OF THE INVENTION An object of the present invention is to provide a multistage centrifugal fan having a rational configuration.

SUMMARY OF THE INVENTION In one aspect of the present invention, a blower is provided that includes a motor, a plurality of centrifugal fans, a housing, a plurality of partition plates, and at least one straightening member. The plurality of centrifugal fans are coaxially arranged in multiple stages, and rotate around a predetermined rotating shaft in accordance with the driving of the motor, thereby sucking air in the axial direction of the rotating shaft and sending it out in the radial direction. It is configured. A housing contains a motor and a plurality of centrifugal fans. The housing also has an intake port for drawing air into the housing and an exhaust port for discharging air that has been compressed and sent out by the plurality of centrifugal fans. The plurality of partition plates are arranged on the suction side of each of the plurality of centrifugal fans in the axial direction of the rotating shaft, and define boundaries of areas corresponding to the respective centrifugal fans. Also, the plurality of partition plates each have a vent provided on the rotating shaft. At least one rectifying member is arranged axially between the plurality of centrifugal fans. Each of the plurality of centrifugal fans has a disk-shaped back plate and a plurality of blades. The back plate has a suction side first surface and a second surface opposite the first surface. A plurality of vanes protrude from the first surface of the back plate. Each of the at least one straightening member has a disk-shaped base plate and a plurality of protrusions. The base plate is arranged to face the second surface of the back plate. Also, the base plate has a third surface facing the second surface and a fourth surface opposite to the third surface. A plurality of protrusions protrude from the base plate and are configured to guide airflow in specific directions. Furthermore, all of the plurality of protrusions are provided on the fourth surface of the base plate and are configured as a plurality of guide vanes that guide the air flow toward the ventilation openings of the partition plate corresponding to the next stage centrifugal fan. It is

In the multi-stage centrifugal fan according to this aspect, the partition plates arranged on the suction side of each of the plurality of centrifugal fans define the boundaries of the regions of each stage. A member is provided. The blades of the centrifugal fan protrude from the suction-side first surface of the back plate, while the guide blades of the straightening member protrude from the fourth surface of the base plate, that is, the surface opposite to the centrifugal fan. Since the third surface of the base plate, that is, the surface on the side of the centrifugal fan, is not provided with a protrusion projecting from the base plate, the base plate and the back plate can be arranged as close as possible. As a result, the air sent radially outward from the centrifugal fan can be prevented from flowing radially inward between the back plate and the base plate due to the pressure difference. Moreover, since the third surface is not provided with a protrusion, the possibility of interference between the centrifugal fan and the rectifying member during assembly can be reduced, and the ease of assembly can be improved. Thus, according to this aspect, a multistage centrifugal fan having a rational configuration is realized.

In this aspect, the motor may be driven by power supplied from a battery, or may be driven by power supplied from an external AC power supply. Also, the motor may be a motor having brushes or a brushless motor. It is preferable to use a brushless motor because it is compact, has a high output, and has a variable number of revolutions.

The number of centrifugal fans (that is, the number of stages) is not particularly limited, and can be appropriately selected according to the wind force required for the blower, for example. As the plurality of centrifugal fans, a rearward fan having rearward blades (also called a turbo fan), a radial fan having radial blades, or a multi-blade fan having forward blades (also called a sirocco fan) can be adopted. In addition, all of the plurality of centrifugal fans do not necessarily have the same structure, but preferably have the same structure from the viewpoint of manufacturing cost and ease of assembly.

The number of straightening members is determined according to the number of centrifugal fans, and is one when the number of centrifugal fans is two, and plural when the number is three or more. Note that when a plurality of rectifying members are provided, not all the rectifying members need to have the same structure, but preferably have the same structure from the viewpoint of manufacturing cost and ease of assembly.

In one aspect of the present invention, the plurality of guide vanes may be arranged such that their radially outer ends are inclined in the direction opposite to the rotation direction of the centrifugal fan. According to this aspect, the air sent out by the centrifugal fan can smoothly flow into the return flow path formed between the adjacent guide vanes along the radially outer end of the guide vanes.

In one aspect of the present invention, the plurality of blades may be arranged so that their radially outer ends are inclined in the direction opposite to the rotation direction of the centrifugal fan. That is, the centrifugal fan may be a rearward fan having rearward blades. According to this aspect, it is possible to realize a multi-stage centrifugal fan that is highly efficient and capable of exhibiting a relatively large air volume while suppressing an increase in size in the radial direction.

In one aspect of the present invention, the plurality of guide vanes may each protrude radially outward from the base plate and reach the inner surface of the housing. According to this aspect, the air sent radially outward by the centrifugal fan can be easily caused to flow into the flow path leading to the next-stage air vent from between the radially outer ends of the guide vanes. . Note that the inner surface of the housing does not have to be the inner surface of the housing itself, but may include the inner surface of a wall that is arranged in the housing and defines the outer circumference of the area corresponding to each fan.

In one aspect of the present invention, the back plate of the centrifugal fan and the base plate of the straightening member may have the same outer diameter. It should be noted that the term "same" as used herein does not necessarily mean that they are exactly the same, but that it is sufficient if they are approximately the same in view of possible errors. According to this aspect, the air delivered from between the radially outer ends of the blades provided on the first surface can flow more easily toward the fourth surface side of the base plate provided with the guide blades. can.

In one aspect of the present invention, the blower is arranged between the last-stage centrifugal fan and the outlet of the plurality of centrifugal fans, and configured to direct the air sent from the last-stage centrifugal fan toward the outlet. A final straightening member may also be provided. According to this aspect, it is possible to efficiently guide the air to the discharge port delivered from the final-stage fan, thereby suppressing a decrease in the wind force.

In one aspect of the present invention, the plurality of partition plates and at least one rectifying member may be configured as separate members. According to this aspect, compared with the case where the partition plate and the rectifying member are configured as a single member, manufacturing costs can be suppressed by making each of them simpler in configuration.

In one aspect of the invention, the stator and rotor of the motor may be arranged between the suction port and the first stage centrifugal fan of the plurality of centrifugal fans. According to this aspect, it is possible to cool the stator and rotor, which are the main body of the motor, by using the air sucked from the suction port by the plurality of centrifugal fans.

It is a perspective view of an air duster. It is a sectional view of an air duster. FIG. 3 is a partially enlarged view of the body housing of FIG. 2; 4 is a cross-sectional view taken along line IV-IV of FIG. 3; FIG. 4 is a partially enlarged view of FIG. 3; FIG. It is a sectional view of a fan. FIG. 4 is a rear view of the main body of the fan; 4 is a perspective view of the main body of the fan; FIG. FIG. 4 is a front view of the main body of the fan; It is a perspective view of a locking member. FIG. 4 is a front view of first stage and second stage rectifying members; FIG. 11 is a front view of a third stage flow straightening member;

An air duster 1 according to an embodiment of the present invention will be described below with reference to the drawings. The air duster 1 shown in FIG. 1 is a type of fan capable of blowing off dust and the like by discharging air from a discharge port 203, and is configured as a hand-held electric tool that is held and used by a user. ing.

First, a schematic configuration of the air duster 1 will be described.

As shown in FIGS. 1 and 2, the outer shell of the air duster 1 is mainly formed by a body housing 2 and a handle 3. As shown in FIGS. The body housing 2 is configured as a hollow body that accommodates a motor 4, a plurality of fans (also called impellers) 6, and the like. In this embodiment, the body housing 2 is generally cylindrical and has a discharge port 203 at one axial end. The handle 3 is configured to be grippable by the user, and protrudes from the body housing 2 in a direction intersecting (substantially perpendicular to) the axis of the body housing 2 . A trigger 311 that can be pushed (pulled) by the user is provided at the base end of the handle 3 (the end connected to the main body housing 2). A battery 340 is detachably attached to the protruding end (tip) of the handle 3 via a battery attachment portion 34 . When the user pulls the trigger 311 , the motor 4 is energized to drive the fan 6 and the compressed air is discharged from the discharge port 203 .

A detailed configuration of the air duster 1 will be described below. In the following, for convenience of explanation, the axial direction of the main body housing 2 (also referred to as the axial direction of the rotation axis A1 of the motor shaft 45 and the fan 6 (hereinafter referred to as the rotation axis A1 direction)) will be referred to as the front-rear direction of the air duster 1. The side on which the discharge port 203 is arranged is defined as the front side, and the opposite side is defined as the rear side. Further, the direction perpendicular to the axis (rotational axis A1) of the main body housing 2 and corresponding to the extending direction of the handle 3 is defined as the vertical direction, the base end side is the upper side, and the projecting end side (the battery 340 is side) is defined as the bottom side. Further, a direction orthogonal to the front-rear direction and the up-down direction is defined as the left-right direction.

The handle 3 and its internal structure will be described.

As shown in FIGS. 1 and 2, the handle 3 includes a cylindrical gripping portion 31 extending generally in the vertical direction, and a rectangular box-shaped gripping portion 31 connected to the lower end of the gripping portion 31 to constitute the lower end of the handle 3 . is configured as a hollow body including the controller accommodating portion 33 of the . The upper end of the handle 3 (grip portion 31 ) is fixed to the body housing 2 with screws, whereby the handle 3 is integrated with the body housing 2 .

The grip portion 31 is a portion that is gripped by the user when the air duster 1 is used (during operation). The trigger 311 is provided on the front side of the upper end portion of the grip portion 31 . A switch 313 is accommodated in the grip portion 31 . The switch 313 is normally kept off, and is turned on when the trigger 311 is pulled. The switch 313 is connected to a later-described controller 331 via wiring (not shown), and is configured to output a signal to the controller 331 according to the operation amount (pull amount) of the trigger 311 when turned on. It is

A controller 331 configured to control various operations of the air duster 1 such as driving control of the motor 4 is accommodated in the controller accommodating portion 33 . In this embodiment, the controller 331 is configured as a microcomputer including a CPU, a ROM, a RAM, and a memory. there is In this embodiment, the controller 331 is configured to steplessly control the number of revolutions of the motor 4 according to the signal output from the switch 313 (that is, the amount of operation of the trigger 311). The maximum rotation speed of the motor 4 corresponding to the maximum operation amount of the trigger 311 is 63,000 revolutions per minute (63,000 rpm).

Furthermore, an operation unit 333 that can be externally operated by the user is provided on the upper portion of the controller housing unit 33 . The operation unit 333 has push buttons for receiving input of various kinds of information. The operation unit 333 is connected to the controller 331 via wiring (not shown), and is configured to output a signal indicating input information to the controller 331 .

A battery mounting portion 34 is provided at the lower end portion of the controller housing portion 33 . The battery mounting portion 34 has an engagement structure capable of sliding engagement with the rechargeable battery 340 and terminals that can be connected to the terminals of the battery 340 as the battery 340 is engaged. Since the configurations of the battery mounting portion 34 and the battery 340 are well known, the description thereof will be omitted here.

Main body housing 2 and its internal structure will be described.

As shown in FIGS. 1 and 2, the main body housing 2 is mostly cylindrical, while the front end is tapered funnel-shaped (conical). A cylindrical tip of this funnel-shaped portion is called a nozzle 231 . The opening of the nozzle 231 constitutes a discharge port 203 through which air compressed within the body housing 2 is discharged to the outside of the body housing 2 . In this embodiment, the ejection port 203 is circular and has a diameter (also referred to as a nozzle diameter) of 6 millimeters (mm). The outlet 203 is arranged on the rotation axis A1. Although details are not shown, a cylindrical attachment having an inner diameter larger or smaller than the nozzle diameter can be attached to and detached from the nozzle 231 . When the attachment is attached to the nozzle 231, the air discharged from the discharge port 203 passes through the attachment and is discharged from the opening at the tip of the attachment. A rear wall defining the rear end portion of the body housing 2 is formed with a plurality of through holes. These through holes form suction ports 201 for sucking air from the outside of the body housing 2 to the inside.

In this embodiment, the body housing 2 is mainly formed of a cylindrical portion 21 and a front cover 23 and a rear cover 25 connected to the cylindrical portion 21 . The body housing 2 is made of synthetic resin.

The tubular portion 21 is a generally cylindrical member. As shown in FIGS. 3 and 4, a plurality of ribs 211 projecting inward (toward the central axis) from the inner peripheral surface are provided at the rear portion of the tubular portion 21 . A front end surface 212 of the rib 211 functions as a positioning surface for positioning the first partition plate 711 (to be described later) and thus the partition structure 7 in the front-rear direction. The front cover 23 is a funnel-shaped member that covers the opening at the front end of the tubular portion 21 . The front cover 23 includes a nozzle 231 and constitutes the front end of the body housing 2 . The rear cover 25 is a circular member that covers the rear end opening of the cylindrical portion 21 . The rear cover 25 is a member forming the rear wall of the main body housing 2 and has a plurality of through holes as the suction port 201 . Further, the rear cover 25 is provided with a plurality of ribs 251 protruding forward. The ribs 251 are configured to support the stator 41 of the motor 4 together with the ribs 211 of the tubular portion 21 .

Further, the rear cover 25 is configured as a holding member for the bearing 47 and has a bearing holding portion 255 provided in the central portion. The bearing holding portion 255 is a bottomed cylindrical portion that opens to the rear end side, and has a bottom wall (front wall) having a through hole and a cylindrical peripheral wall. A bearing 47 is fitted in the bearing holding portion 255 . The bearing 47 is fastened to the rear cover 25 by a retainer 256 with the outer ring 471 of the bearing 47 in contact with the bottom wall of the bearing holding portion 255 . The retainer 256 is screwed from the rear side of the bearing 47 into a female screw portion formed on the inner peripheral surface of the peripheral wall.

As described above, the body housing 2 accommodates the motor 4 and the fan 6 . More specifically, as shown in FIGS. 3 and 4 , the main body 40 of the motor 4 is arranged in the rear part of the main body housing 2 and the fan 6 is arranged in front of the motor main body 40 . That is, the motor 4 is arranged between the suction port 201 and the fan 6 (on the upstream side of the fan 6) in the air flow path in the body housing 2 from the suction port 201 to the discharge port 203. FIG.

A brushless motor is employed as the motor 4 in this embodiment. The motor 4 includes a body portion 40 including a stator 41 and a rotor 43 , and a motor shaft 45 extending from the rotor 43 and rotating integrally with the rotor 43 .

The stator 41 is housed in a cylindrical case 411 and held within the rear end portion of the body housing 2 . More specifically, the case 411 of the stator 41 is sandwiched and supported between the ribs 211 of the cylindrical portion 21 and the ribs 251 of the rear cover 25 .

The motor shaft 45 extends in the front-rear direction along the axis of the body housing 2 . The motor shaft 45 of this embodiment is much longer than the body portion 40 and extends from the front end to the rear end of the body housing 2 . The motor shaft 45 is rotatably supported by bearings 46 and 47 with respect to the main body housing 2 around the rotation axis A1. In this embodiment, both the bearings 46 and 47 are ball bearings having an outer ring, an inner ring, and balls as rolling elements. A bearing 46 that supports the front end of the motor shaft 45 is held by the main body housing 2 via a rectifying member 75 which will be described later. A bearing 47 that supports the rear end of the motor shaft 45 is held by the bearing holding portion 255 of the rear cover 25 described above.

The rotor 43 is fixed to the rear end of the motor shaft 45 and is arranged inside the stator 41 in front of the rear bearing 47 . A balance ring 431 is attached to the motor shaft 45 in front of the rotor 43 . The balance ring 431 is made of a machinable material (e.g., copper) and is machined as needed to optimize dynamic balance during rotation of the rotor 43. . Furthermore, the motor shaft 45 has a flange 451 projecting radially outward on the front side of the balance ring 431 . A front end portion of the motor shaft 45 is configured as a male screw portion 453 having a thread cut on the outer peripheral surface thereof. Three fans 6, which will be described later, are attached to a portion of the motor shaft 45 between the male screw portion 453 and the flange 451 (hereinafter referred to as a fan attachment portion 455). The fan mounting portion 455 has a larger diameter than the male threaded portion 453 and has a uniform diameter.

As shown in FIGS. 3 and 4, in this embodiment, the air duster 1 has three fans 6 having the same configuration. The fan 6 is arranged coaxially on the motor shaft 45 and is configured to rotate integrally with the motor shaft 45 around the rotation axis A1 as the motor 4 is driven. The fan 6 is a centrifugal fan that sucks air in the direction of the rotation axis A1 and sends it radially outward. The three fans 6 are arranged in three partitioned areas (also called rooms). In the following, when distinguishing between the three fans 6, the first stage side (the side of the suction port 201) can be said to be the most upstream side in the direction of air flow in the main body housing 2. In this embodiment, the rear end of the main body housing 2 side) are also referred to as a first fan 601, a second fan 602, and a third fan 603 in order. Also, the regions (rooms) corresponding to the first fan 601, the second fan 602, and the third fan 603 are also called a first region R1, a second region R2, and a third region R3, respectively.

Here, partitions inside the main body housing 2 will be described. As shown in FIGS. 3 and 4, three circular partition plates 71 having a through hole in the center are arranged in the body housing 2 . The three partition plates 71 are arranged behind the three fans 6 (also referred to as the front stage side or the suction side). A partition plate 71 arranged on the rear side of the first fan 601 defines a boundary between an area in which the motor 4 is accommodated (hereinafter referred to as a motor area) and an area in which the fan 6 is accommodated (hereinafter referred to as a fan area). define. A partition plate 71 arranged behind the second fan 602 defines a boundary between the first region R1 and the second region R2. A partition plate 71 arranged behind the third fan 603 defines a boundary between the second region R2 and the third region R3. In addition, hereinafter, when the three partition plates 71 are separately indicated, they are also referred to as a first partition plate 711, a second partition plate 712, and a third partition plate 713 in order from the first stage side. The outer diameter of the partition plate 71 is approximately equal to the inner diameter of the body housing 2 (cylindrical portion 21). A central through-hole of each partition plate 71 is arranged on the rotation axis A1 and constitutes a vent hole 710 that communicates the front (rear) area and the next (front) area.

In each of the first region R1 and the second region R2, the front side of the fan 6 (the next stage side, which can also be called the discharge port 203 side) directs the air sent out by the fan 6 radially inward and forwards to the next stage. A straightening member 73 is arranged for guiding. The two straightening members 73 have the same configuration. Further, in the third region R<b>3 , a rectifying member 75 is arranged in front of the fan 6 to guide the air sent radially outward by the fan 6 radially inward to the discharge port 203 . In other words, in this embodiment, the rectifying member 73 or 75 for guiding the air flow in a specific direction is provided corresponding to each stage of the fan 6 .

While the fan 6 is assembled to the motor shaft 45 , the partition plate 71 and the straightening members 73 and 75 are members assembled to the main body housing 2 . In this embodiment, the three fans 6 are attached to the motor shaft 45 via bearings 46 . On the other hand, the partition plate 71 and the rectifying members 73 and 75 are assembled to the main body housing 2 via bearings 46 integrally with spacers 77 arranged therebetween. This point will be detailed later.

A detailed configuration of the fan 6 will be described below. As mentioned above, the fan 6 is a centrifugal fan. As shown in FIGS. 5 and 6, the fan 6 is a so-called open impeller and includes a hub 61, a back plate 631, and a plurality of blades 633. As shown in FIGS.

The hub 61 is a tubular portion having a through hole through which the motor shaft 45 is inserted. The back plate 631 is a disc-shaped portion protruding radially outward from the hub 61 . In addition, the back plate 631 of the present embodiment is flat and has a substantially uniform thickness. The blade 633 protrudes rearward from the surface of the back plate 631 on the suction port 201 side (suction side), that is, from the rear surface. The gap between the blades 633 of the fan 6 and the partition plate 71 on the rear side (suction side) is minimized in order to prevent the air sent radially outward from flowing back into this gap. there is The blades 633 curve and radially extend from the outer circumference of the hub 61 (more specifically, a boss 635 described later) to the outer edge of the back plate 631 . The air sucked in the direction of the rotation axis A1 flows radially outward through a channel defined by the back plate 631 and the adjacent blades 633 (hereinafter referred to as a fan channel), and reaches the radially outer ends of the blades 633. It flows out from the opening (outlet) in between.

In this embodiment, the fan 6 is a rearward fan (also called a turbo fan) having rearward blades, and as shown in FIG. is tilted in the opposite direction. By adopting such a rear-facing fan, compared to the case of adopting a radial fan with radial blades, a multi-stage centrifugal blower that can produce a relatively large air volume while suppressing the increase in size in the radial direction is achieved. can be realized.

In addition, in this embodiment, the fan 6 is configured by connecting three members configured as separate members in a fixed manner. More specifically, as shown in FIG. 6, the fan 6 is composed of a sleeve 610, a main body 63, and a lock member 65. As shown in FIG. In this embodiment, the sleeve 610 and the locking member 65 are made of iron to ensure strength, and the main body 63 is made of an aluminum alloy to reduce weight.

As shown in FIG. 5, the sleeve 610 is a cylindrical member fitted around the outer periphery of the motor shaft 45 and has an inner diameter approximately equal to the diameter of the motor shaft 45 . As shown in FIG. 6, approximately half of the sleeve 610 is configured as a large diameter portion 612 and the other half is configured as a small diameter portion 614 having a smaller outer diameter. A flange 613 is provided at one end of the large diameter portion 612 opposite to the small diameter portion 614 . Although the details will be described later, the main body 63 is press-fitted to the outer periphery of the large diameter portion 612 . The flange 613 functions as a positioning portion and a retaining portion for the main body 63 .

As shown in FIGS. 5 to 8, the main body 63 is a member including a cylindrical boss 635, the back plate 631 and the blades 633 described above. The boss 635 is a portion that is press-fitted into the large-diameter portion 612 of the sleeve 610 and has an inner diameter slightly smaller than the outer diameter of the large-diameter portion 612 . The back plate 631 protrudes radially outward from the front end of the boss 635 . The outer diameter of the back plate 631 is smaller than the inner diameter of the body housing 2 (cylindrical portion 21). In this embodiment, the outer diameter of the back plate 631 (that is, the outer diameter of the fan (impeller) 6 (also referred to as fan diameter)) is 50 mm. Further, as shown in FIGS. 5 and 9, a plurality of protrusions 632 are provided on the surface of the back plate 631 opposite to the surface on which the blades 633 are provided, that is, on the front surface. In this embodiment, four protrusions 632 are arranged at regular intervals around the through hole in the central portion of the main body 63 .

As shown in FIG. 6, the locking member 65 is a member that is press-fitted onto the outer periphery of the small diameter portion 614 of the sleeve 610 to more firmly fix the sleeve 610 and the main body 63 together. As shown in FIGS. 6 and 10 , the lock member 65 is a member including a cylindrical boss 651 and a flange 653 projecting radially outward from one axial end of the boss 651 . Boss 651 has an inner diameter slightly smaller than the outer diameter of small diameter portion 614 . A plurality of recesses 654 are provided on the periphery of the flange 653 . In this embodiment, four recesses 654 are provided at regular intervals in the circumferential direction corresponding to the four protrusions 632 (see FIG. 9) of the main body 63 . Each recess 654 has a shape that matches the protrusion 632 .

The fan 6 is assembled by the sleeve 610, the main body 63 and the locking member 65 constructed as described above as follows. First, the main body 63 is arranged so that the protrusion 632 is located on the opposite side of the flange 613 and is press-fitted onto the outer circumference of the large diameter portion 612 of the sleeve 610 . Then, the lock member 65 is pressed into the small diameter portion 614 of the sleeve 610 while the lock member 65 is circumferentially positioned with respect to the main body 63 so that the recess 654 engages the projection 632 . Thereby, the sleeve 610, the main body 63 and the lock member 65 are integrated, and the fan 6 is completed. When the fan 6 is completed, the sleeve 610, the boss 635 of the main body 63, and the boss 651 of the lock member 65 constitute the hub 61. As shown in FIG. In this embodiment, the hub 61 also functions as a spacer that defines the spacing between the back plates 631 of the adjacent fans 6 when the three fans 6 are arranged in series on the motor shaft 45 .

A detailed configuration of the straightening member 73 will be described. As shown in FIGS. 5 and 11, the straightening member 73 includes a base plate 731 and a plurality of guide vanes 735. As shown in FIGS. In addition, in the present embodiment, the base plate 731 and the guide vanes 735 are integrally formed of an aluminum alloy.

The base plate 731 is a disk-shaped portion having a through hole 733 in the center. One of the two plate surfaces of the base plate 731 is flat. The other surface has a projecting portion 732 in the central portion that protrudes while gently curving toward the center. The base plate 731 is arranged so that the flat side faces the front surface of the back plate 631 of the fan 6 (the surface opposite to the blades 633 provided) in a non-contact manner. The gap between the back plate 631 and the base plate 731 is minimized in order to prevent the air sent from the outlet of the fan passage from flowing back into this gap. Also, the outer diameter of the base plate 731 is approximately equal to the outer diameter of the back plate 631 of the fan 6 . The through hole 733 is configured so that the base plate 731 does not come into contact with the fan 6 when facing the back plate 631 .

The guide vanes 735 are vanes for guiding air radially inward. The guide vanes 735 protrude forward from the surface of the two plate surfaces of the base plate 731 opposite to the surface facing the fan 6 (back plate 631) in the same stage, that is, from the front surface. Further, the guide vanes 735 extend radially while being curved from the outer periphery of the projecting portion 732 of the base plate 731 . Note that the number of guide vanes 735 is less than the number of vanes 633 of the fan 6 . The air sent radially outward from the outlet of the fan passage passes through a flow path (hereinafter referred to as a return flow path) defined by the base plate 731, the adjacent guide vanes 735, and the partition plate 71 on the next stage in the radial direction. flow inward. The radially outer (air-inflow side) end of the guide vane 735 is inclined in the direction opposite to the rotation direction R of the fan 6 . The radially outer end of the guide vane 735 protrudes radially outward from the outer edge of the base plate 731 and reaches the inner surface of the main body housing 2 (cylindrical portion 21). That is, the outer diameter of the rectifying member 73 is substantially equal to the inner diameter of the body housing 2 (cylindrical portion 21).

In this embodiment, the front end of the rectifying member 73 (the guide vane 735) is in contact with the partition plate 71 on the next stage side. Therefore, it can be said that the rectifying member 73 and the partition plate 71 on the next stage integrally constitute the partition structure 7 that defines the boundary with the next stage. Although it is possible to integrally mold the rectifying member 73 and the partition plate 71 as a single member, by forming them as separate members as in the present embodiment, the respective structures can be simplified and the manufacturing cost can be reduced. can be suppressed.

A detailed configuration of the straightening member 75 will be described. As shown in FIGS. 5 and 12, the straightening member 75 includes a cylindrical portion 751 and a plurality of guide vanes 753. As shown in FIGS. Further, in this embodiment, the straightening member 75 also serves as a holding member for the bearing 46 . Therefore, the straightening member 75 has a bearing holding portion 755 . In addition, in this embodiment, the cylindrical portion 751, the guide vane 753, and the bearing holding portion 755 are integrally formed of an aluminum alloy.

The cylindrical portion 751 is a portion that is fitted into the cylindrical portion 21 of the main body housing 2 and has an outer diameter approximately equal to the inner diameter of the cylindrical portion 21 . The guide vane 753 is a vane for guiding air radially inward, and radially connects the bearing holding portion 755 and the cylindrical portion 751 . The guide vanes 753 extend radially while being curved similarly to the guide vanes 735 of the rectifying member 73 , and the radial outer ends of the guide vanes 753 are inclined in the direction opposite to the rotation direction R of the fan 6 . The bearing holding portion 755 is provided at the center of the front end portion of the cylindrical portion 751 . The bearing holding portion 755 is a bottomed cylindrical portion that opens to the front end side, and has a bottom wall (rear wall) having a through hole 756 and a cylindrical peripheral wall. The diameter of the through hole 756 is set larger than the outer diameter of the front end portion (lock member 65 ) of the hub 61 of the fan 6 . A bearing 46 is fitted in the bearing holding portion 755 . The outer ring 461 of the bearing 46 is in contact with the bottom wall of the bearing holding portion 755 . Further, the inner ring 463 of the bearing 46 is press-fitted to the front end portion of the motor shaft 45 (fan mounting portion 455 ) while being in contact with the front end of the hub 61 of the third fan 603 .

A male threaded portion 453 of the motor shaft 45 protrudes forward from the bearing 46 . A nut 81 and a locking nut 83 are fastened to the male screw portion 453 . A washer 89 is arranged between the bearing 46 and the nut 81 . In this embodiment, the nut 6 fastens the three fans 6 to the motor shaft 45 via the inner ring 463 of the bearing 46, and fastens the partition structure 7 and the like to the main body housing 21 via the outer ring 461 of the bearing 46. are doing. This point will be described in detail later.

A detailed configuration of the spacer 77 will be described. The spacer 77 abuts on the partition plate 71 on the rear side (previous stage side) and the straightening members 73 and 75 in each step (each of the first region R1 to the third region R3) so that the partition plate 71 and the straightening member 73 are in contact with each other. , 75 to position the rectifying members 73 and 75 in the front-rear direction. Specifically, three spacers 77 are placed between the first partition plate 711 and the straightening member 73 corresponding to the first fan 601, and between the second partition plate 712 and the straightening member 73 corresponding to the second fan 602. , and between the third partition plate 713 and the rectifying member 75 corresponding to the third fan 603 . In this embodiment, the spacer 77 is a cylindrical member having an outer diameter approximately equal to the inner diameter of the tubular portion 21, and is made of a thin aluminum alloy plate. The axial length of the spacer 77 is such that the gap between the front surface of the back plate 631 of the fan 6 in the same stage and the rear surface of the base plate 731 of the straightening member 73 (two surfaces facing each other) is minimized. is set.

The air flow when the motor 4 is driven will be described below. When the motor 4 is driven and the three fans 6 rotate integrally with the motor shaft 45, air is sucked into the body housing 2 through the suction port 201 (see FIG. 2). The sucked air passes through the motor area while cooling the motor body 40, and as indicated by the thick arrow in FIG. 1 flows into region R1. Then, it passes through the fan channel of the first fan 601 and is sent out from the outlet of the fan channel to the outside in the radial direction of the first fan 601 . In FIG. 5, for the sake of convenience, the flow of air in the upper half of the body housing 2 is indicated by thick arrows, but the flow in the lower half is the same.

The sent air is directed by the inner peripheral surface of the spacer 77 and flows into the return flow path from between the radially outer ends of the guide vanes 735 of the rectifying member 73 . In this embodiment, as described above, the back plate 631 of the fan 6 and the base plate 731 of the straightening member 73 have substantially the same outer diameter. Further, the guide vanes 735 of the straightening member 73 protrude radially outward from the base plate 731 and reach the inner surface of the main body housing 2 . According to such a configuration, the air sent from the outlet of the fan passage can be easily caused to flow into between the radially outer ends of the guide vanes 735 (the ends protruding from the base plate 731) from the rear side. , can easily flow to the return channel formed on the front side of the base plate 731 . Furthermore, since the guide vanes 735 are arranged so that their radially outer ends are inclined in the direction opposite to the rotation direction of the fan 6, the air sent out from the fan 6 is directed radially of the guide vanes. Along the outer edge it can flow smoothly into the return channel. The air guided radially inward in the return channel flows into the second region R2 through the vent 710 of the second partition plate 712 .

The air that has flowed into the second region R2 is sent radially outward through the fan passage of the second fan 602, is redirected by the inner peripheral surface of the spacer 77, and flows easily and smoothly into the return passage of the rectifying member 73. flow into Furthermore, the air guided radially inward in the return channel flows into the third region R3 through the vent 710 of the third partition plate 713 . The air that has flowed into the third region R3 is sent out radially outward through the fan passage of the third fan 603, is redirected by the inner peripheral surface of the spacer 77, and is formed between the guide vanes 753 of the straightening member 75. flow into the return channel where Similarly to the guide vanes 735 of the straightening member 73 , the guide vanes 753 of the straightening member 75 also protrude radially outward from the base plate 731 and reach the inner surface of the cylindrical portion 751 . In addition, the radially outer end of the guide vane 753 is arranged so as to be inclined in the direction opposite to the rotation direction of the fan 6 . Therefore, the air sent out from the third fan 603 easily and smoothly flows into the return passage of the straightening member 75 .

The inflowing air is guided radially inward in the return channel by the guide vanes 753, passes through the nozzle 231 of the front cover 23, and is discharged from the discharge port 203 on the rotation axis A1. By arranging the rectifying member 75 between the final-stage third fan 603 and the discharge port 203 in this way, the air sent from the third fan 603 is efficiently guided to the discharge port 203, and the wind power is reduced. Decrease can be suppressed.

Assembling the air duster 1 (in particular, assembling the fan 6 to the motor shaft 45 and assembling the partition plate 71, the spacer 77, and the rectifying members 73 and 75 to the main body housing 2) will be described below.

First, the motor 4 is housed inside the body housing 2 . Specifically, the stator 41 housed in a case 411 is arranged at the rear portion of the cylindrical portion 21 from which the front cover 23 and the rear cover 25 are removed, and the rear cover 25 is screwed into a cylindrical shape by screws 29 . It is fixed to the part 21 . By attaching the rear cover 25 to the cylindrical portion 21, the stator 41 is supported within the main body housing 2 by the ribs 211 and 251 (see FIGS. 3 and 4). Also, the motor shaft 45 to which the rotor 43 and the balance ring 431 are fixed is arranged inside the tubular portion 21 , and the rear end portion of the motor shaft 45 is press-fitted into the inner ring 473 of the bearing 47 .

Subsequently, the first partition plate 711 partitions the motor area and the fan area (more specifically, the first area R1). Specifically, the first partition plate 711 is inserted into the interior through the opening at the front end of the cylindrical portion 21 with the motor shaft 45 inserted therethrough. The outer edge of the first partition plate 711 contacts the front end surface 212 of the rib 211 of the tubular portion 21, and the first partition plate 711 is positioned in the front-rear direction with respect to the tubular portion 21 (see FIG. 4).

Subsequently, the arrangement of the structure in the first stage and the partitioning of the first region R1 and the second region R2 are performed in the following procedure.

First, the first-stage spacer 77 is fitted into the cylindrical portion 21 from the front end side while the motor shaft 45 is inserted therethrough. The spacer 77 contacts the outer edge of the rear end surface of the first partition plate 711 and is positioned in the front-rear direction. Subsequently, the first fan 601 is fitted to the outer circumference of the motor shaft 45 from the front end side of the motor shaft 45 and inserted into the cylindrical portion 21 . The rear end of the hub 61 (specifically, the flange 613) contacts the front end surface of the flange 451 of the motor shaft 45, and the first fan 601 is positioned in the longitudinal direction with respect to the motor shaft 45 (see FIG. 5). .

Further, the rectifying member 73 is fitted into the cylindrical portion 21 from the front end side with the motor shaft 45 inserted therethrough. The rear end surface of the radially outer end portion of the guide vane 735 of the rectifying member 73 abuts the front end surface of the spacer 77, and the rectifying member 73 is positioned in the front-rear direction. As a result, the front side (next stage side) of the first fan 601 is formed in a state where a minimum gap is formed between the front surface of the back plate 631 of the fan 6 in the same stage and the rear surface of the base plate 731 of the rectifying member 73 . A rectifying member 73 is arranged at . Further, the straightening member 73 is arranged radially outside the hub 61 in a state in which the front portion (locking member 65) of the hub 61 of the fan 6 and the projection 632 are inserted into the through hole 733 (see FIG. 5).

Furthermore, the second partition plate 712 is inserted into the tubular portion 21 . The outer edge of the second partition plate 712 abuts on the front end surface of the first stage rectifying member 73 to be positioned in the front-rear direction. This completes the arrangement of the first-stage fan 6, the spacer 77, and the rectifying member 73, and the partitioning of the first region R1 and the second region R2 (see FIG. 5).

Subsequently, the arrangement of the structure of the second stage and the partitioning of the second region R2 and the third region R3 are performed in the following procedure.

The method of arranging the structure of the second stage is substantially the same as the method of the first stage described above. Specifically, a spacer 77 corresponding to the second stage is fitted inside the cylindrical portion 21 and positioned in the front-rear direction. The second fan 602 is fitted onto the motor shaft 45 and positioned so that the rear end of the hub 61 contacts the front end of the hub 61 of the first fan 601 in the preceding stage. The front end of the hub 61 of the positioned second fan 602 is arranged inside the vent hole 710 of the second partition plate 712 . Also, the blade 633 is arranged at a position slightly spaced forward from the second partition plate 712 . A rectifying member 73 corresponding to the second stage and a third partition plate 713 partitioning the second region R2 and the third region R3 are fitted in order inside the cylindrical portion 21 and positioned in the front-rear direction. This completes the arrangement of the second-stage fan 6, the spacer 77, and the rectifying member 73, and the partitioning of the second region R2 and the third region R3 (see FIG. 5).

Subsequently, the structure of the third stage is arranged in the same procedure as the second stage. Specifically, a spacer 77 corresponding to the third stage is fitted inside the cylindrical portion 21 and positioned in the front-rear direction. The third fan 603 is fitted onto the motor shaft 45 and positioned so that the rear end of the hub 61 contacts the front end of the hub 61 of the second fan 602 in the preceding stage. A rectifying member 75 corresponding to the third stage is fitted inside the tubular portion 21 and positioned in the front-rear direction. This completes the placement of the third-stage fan 6, spacer 77, and rectifying member 75. FIG. A front end portion of the hub 61 of the third stage fan 6 protrudes into the bearing holding portion 755 through the through hole 756 (see FIG. 5).

Note that when the arrangement of the structure of the third stage is completed, the three fans 6 of the first stage to the third stage are rotated in the direction of the rotation axis A1 (the front-rear direction) while the adjacent hubs 61 are in contact with each other. While being arranged in series, the rear end (flange 613 ) of the hub 61 of the first fan 601 contacts the front end of the flange 451 of the motor shaft 45 . However, the three fans 6 are not fixed to the motor shaft 45 . The first partition plate 711, the spacer 77, the rectifying member 73, the second partition plate 712, the spacer 77, the rectifying member 73, the third partition plate 713, the spacer 77, and the rectifying member 75 have outer edges of adjacent members. While being in contact with each other, they are arranged in series in the direction of the rotation axis A1 (front-rear direction), and the outer edge of the rear end surface of the first partition plate 711 is aligned with the front end of the rib 211 in the main body housing 2 (cylindrical portion 21). Abut on the surface. However, these members are not fixed to the body housing 2 .

Subsequently, the three fans 6 are fastened to the motor shaft 45 by the nuts 81, and the partition plate 71, the spacer 77, and the rectifying members 73 and 75 are fastened to the main body housing 2 by the following procedure.

First, the bearing 46 is loosely fitted to the male screw portion 453 (front end portion) of the motor shaft 45 , and part of it is arranged in the front end portion of the bearing holding portion 755 . Furthermore, an annular washer 89 is fitted to the male screw portion 453 on the front side of the bearing 46 . The inner diameter of the washer 89 is substantially equal to the outer diameter of the male screw portion 453 , and the outer diameter of the washer 89 is smaller than the inner diameter of the outer ring 461 of the bearing 46 . Therefore, the washer 89 contacts only the inner ring 463 of the bearing 46 and does not contact the outer ring 461 . Subsequently, the nut 81 is fastened to the male screw portion 453 from the front side of the washer 89 . As the tightening progresses and the nut 81 moves rearward of the motor shaft 45 , the bearing 46 is pressed via the washer 89 and moves rearward within the bearing holding portion 755 , and the inner ring 463 moves toward the fan mounting portion 455 . It is pressed into the front end.

With the inner ring 463 of the bearing 46 in contact with the front end of the hub 61 of the third fan 603 and the outer ring 461 in contact with the bottom wall of the bearing holding portion 755, the nut 81 is further tightened. As a result, the washer 89, the inner ring 463 of the bearing 46, the hub 61 of the third fan 603, the hub 61 of the second fan 602, and the hub 61 of the first fan 601 are clamped between the nut 81 and the flange 451, and the motor shaft It is clamped to the motor shaft 45 by the axial force acting on 45 . Further, the outer ring 461 of the bearing 46, the rectifying member 75, the spacer 77, the third partition plate 713, the rectifying member 73, the spacer 77, the second partition plate 712, the rectifying member 73, the spacer 77, the first partition plate 711, the nut 81 and the rib 211, and fastened to the main body housing 2 by axial force.

After that, in order to prevent the nut 81 from loosening, the locking nut 83 is tightened to the male screw portion 453 . Furthermore, the front cover 23 is screwed onto the front end of the tubular portion 21 . This completes the assembly of the body housing 2 . Further, the handle 3 is fixed to the body housing 2, and the assembly of the air duster 1 is completed.

As described above, the air duster 1 of this embodiment is a three-stage centrifugal blower, and the partition plate 71 (first partition plate 711 The boundaries of the areas of each stage are demarcated by the third partition plate 713). In stages other than the final stage (that is, the first stage and the second stage), rectifying members 73 are provided corresponding to the fans 6 (the first fan 601 and the second fan 602). The blades 633 of the fan 6 protrude from the rear surface of the back plate 631 on the suction side, while the guide blades 735 of the straightening member 73 protrude from the front surface of the base plate 731, that is, the surface opposite to the fan 6. do. Since the rear surface of the base plate 731, that is, the surface on the side of the fan 6, is not provided with a protrusion such as a blade that guides the flow of air in any direction, the base plate 731 and the back plate 631 are arranged as close as possible. be able to. As a result, the air sent radially outward from the fan 6 can be prevented from flowing radially inward between the back plate 631 and the base plate 731 due to the pressure difference. Further, since no projecting portion is provided on the rear surface of the base plate 731, the possibility of interference between the fan 6 and the rectifying member 73 during assembly can be reduced, and the assembling efficiency can be improved. Thus, the air duster 1 having a rational configuration is realized.

In addition, in the air duster 1 of the present embodiment, two partition structures 7 (rectifying member 73 and second partition plate 712, and rectifying The interior of the body housing 2 is partitioned into a first region R1 to a third region R3 by the member 73 and the third partition plate 713). The three fans 6 are fastened to the motor shaft 45 by a single common nut 81, and the two partition structures 7 (more specifically, the two partition structures 7, the first partition plate 711, the rectifier A member 75 and three spacers 77 )) are fastened to the main housing 2 .

With such a configuration, as described above, in assembling the air duster 1, the work of assembling the fan 6 to the motor shaft 45 and the work of assembling the partition structure 7 to the main body housing 2 are performed using the single nut 81. can be done at once. Thus, the air duster 1 is realized as a multi-stage blower with excellent assembling efficiency. In particular, in this embodiment, the fastening of the fan 6 and the partition structure 7 is performed by screwing the nut 81, which is a threaded member, onto the male threaded portion 453 of the motor shaft 45, so that the assembly work is very easy. be. Furthermore, by screwing the locking nut 83 onto the motor shaft 45 in addition to the nut 81, the fan 6 and the partition structure 7 can be tightened more securely.

Further, in this embodiment, the nut 81 fastens the fan 6 to the motor shaft 45 via the inner ring 463 of the bearing 46, and fastens the partition structure 7 to the main body housing 2 via the outer ring 461. . Thus, by utilizing the bearing 46 having the outer ring 461 and the inner ring 463 that can move relative to each other and rotatably supporting the motor shaft 45, the fan 6 and the partition structure 7 can be attached by a single nut 81. Different routes can be easily fastened. In addition, looseness of the motor shaft 45 can be suppressed, and the rotor 43 can be appropriately positioned with respect to the stator 41 . Furthermore, since the fan mounting portion 455 of the motor shaft 45 has a uniform diameter, the motor shaft 45 can be easily manufactured, and all the three fans 6 fastened to the motor shaft 45 have the same structure. be able to.

In addition, in the present embodiment, each partition structure 7 has a partition plate 71 that defines a boundary with the next stage and has a vent hole 710 that allows air to flow into the next stage. and a straightening member 73 that directs the air delivered by 6 to the radially inward, ie, vent 710 . Therefore, in each of the first stage and the second stage, the structure for efficiently guiding the air sent out by the fan 6 to the suction area of the next stage fan 6 is easily assembled to the main body housing 2 by the nut 81. be able to. Furthermore, in the present embodiment, the third stage, which is the final stage, is also provided with a rectifying member 75 configured to direct the air sent from the third fan 603 toward the discharge port 203 . The rectifying member 75 is also fastened to the main body housing 2 with a nut 81 together with the partition structure 7 . Therefore, the structure for efficiently guiding the air sent from the third fan 603 to the discharge port and suppressing the reduction of the wind force can be easily assembled to the main body housing 2 .

The details of numerical setting of the specifications of the air duster 1 will be described below.

In this embodiment, the air duster 1 is an electric multi-stage blower that is small in size but capable of generating sufficient wind power (discharging capacity) to blow away dust and the like when the motor 4 is driven at the maximum rotational speed. It is configured. Generally, a wind force in the range of 1 Newton (N) to 3N is considered sufficient to blow away dust and the like. This wind force value is a value measured according to the "ANSI B175.2 standard" defined by the American National Standards Institute (abbreviated as ANSI).

In this embodiment, the diameter of the discharge port 203 of the air duster 1 (nozzle diameter), the outer diameter of the fan 6 (fan diameter), and the maximum rotation speed of the motor 4 are changed according to the required wind force in the following procedure. selected by

数式１中の空気の密度ρは既知の値であるから、ノズル径ｄを選定すれば、数式１に基づき、所望の風力Ｆを得るために必要な風量Ｑを算出することができる。本実施形態では、ノズル径ｄは、本体ハウジング２の小型化に鑑み、２．５ｍｍから１０ｍｍの範囲内で選定される。なお、できるだけ広範囲に空気を吹き付けて効率的に塵埃を吹き飛ばすべく、ノズル径ｄは、５ｍｍから１０ｍｍの範囲内で選定されるとより好ましい。このような範囲から選定されたノズル径ｄに応じて、必要な風量Ｑが算出される。更に、吐出口２０３の面積Ａおよび風量Ｑとの関係（Ｑ＝ＡＶ）から、風速Ｖが算出される。 First, the required wind force F (Newton: N) is selected within the range of 1N to 3N. Here, the density of air is ρ (kilogram per cubic meter: kg/m ³ ), the volume of air passing through the discharge port 203 is Q (cubic meter per second: m ³ /s), and the wind speed is V (meters per second: m/ s), the area of the discharge port 203 is A (square meters: m ² ), and the nozzle diameter is d (meters: m), the wind force F is expressed by the following Equation 1.

Since the air density ρ in Equation 1 is a known value, the air volume Q required to obtain the desired wind force F can be calculated based on Equation 1 by selecting the nozzle diameter d. In the present embodiment, the nozzle diameter d is selected within a range of 2.5 mm to 10 mm in view of miniaturization of the main body housing 2 . In addition, it is more preferable that the nozzle diameter d is selected within the range of 5 mm to 10 mm in order to efficiently blow off the dust by blowing air over as wide a range as possible. The necessary air volume Q is calculated according to the nozzle diameter d selected from such a range. Further, the air velocity V is calculated from the relationship between the area A of the discharge port 203 and the air volume Q (Q=AV).

なお、数式２中の背圧Ｐ_ｂは大気圧で既知の値であり、空気の密度ρと比熱比γも既知の値である。よって、数式２に基づき、風速Ｖを得るのに必要な圧力Ｐ（要求圧力Ｐともいう）を算出することができる。 Furthermore, when the pressure of the air discharged from the discharge port 203 is P (pascal: Pa), the back pressure is P _b (Pa), and the specific heat ratio of the air is γ, the wind speed V is expressed by the following equation 2. .

The back pressure _Pb in Equation 2 is a known value at atmospheric pressure, and the air density ρ and the specific heat ratio γ are also known values. Therefore, based on Equation 2, the pressure P required to obtain the wind speed V (also referred to as the required pressure P) can be calculated.

なお、数式３中の滑り係数ｋおよび空気の密度ρは既知の値である。よって、要求圧力Ｐを理論締切圧力Ｐ_ｔｈとして、数式３に基づき、要求圧力Ｐを得るために必要なファン径Ｄ_２と最高回転数ｎの組み合わせを選定することができる。本実施形態では、ファン径Ｄ_２は、本体ハウジング２の小型化に鑑み、３０ｍｍから７０ｍｍの範囲内、より好ましくは３０ｍｍから５０ｍｍの範囲内で選定される。また、ノズル径ｄおよびファン径Ｄ_２を比較的小さく設定する代わりに、モータ４の最高回転数ｎは、５０,０００ｒｐｍから１２０,０００ｒｐｍという比較的高い数値範囲内で選定される。なお、コストの抑制等に鑑みれば、モータ４の最高回転数ｎは、５０,０００ｒｐｍから７０,０００ｒｐｍの範囲内で選定されることが好ましい。 Furthermore, the theoretical shut-off pressure (the pressure theoretically obtained when the discharge port 203 is completely blocked) is P _th (Pa), the slip coefficient is k, the peripheral speed of the fan 6 is u ₂ (m/s), the motor 4 The theoretical shut-off pressure P _th can be expressed by the following Equation 3, where n is the maximum number of revolutions (revolutions per minute: rpm) and D ₂ (m) is the diameter of the fan.

The slip coefficient k and air density ρ in Expression 3 are known values. Therefore, it is possible to select the combination of the fan diameter _D2 and the maximum rotation speed n required to obtain the required pressure P based on Equation 3, with the required pressure P being the theoretical shut-off pressure _Pth . In this embodiment, the fan diameter _D2 is selected within the range of 30 mm to 70 mm, more preferably within the range of 30 mm to 50 mm, in view of miniaturization of the main body housing 2 . Also, instead of setting the nozzle diameter d and the fan diameter _D2 relatively small, the maximum rotational speed n of the motor 4 is selected within a relatively high numerical range of 50,000 rpm to 120,000 rpm. In view of cost reduction, etc., it is preferable that the maximum rotation speed n of the motor 4 is selected within the range of 50,000 rpm to 70,000 rpm.

Here, since the theoretical cutoff pressure _Pth is the theoretical maximum pressure when the discharge port 203 is completely blocked, the pressure of the air actually discharged is considered to be about 20% of that. Therefore, if only one fan 6 is used, the required pressure P cannot actually be obtained with the fan diameter _D2 and the maximum rotational speed n selected from the above ranges. Therefore, a combination of the fan diameter _D2 and the maximum rotational speed n is selected so that the required pressure P can be achieved by arranging the fans 6 in multiple stages.

In this embodiment, the required wind force F is 1.5 N, and the nozzle diameter, fan diameter, maximum rotation speed of the motor 4, and the number of stages of the fan 6 are determined according to the procedure described above. Specifically, the nozzle diameter is 6 mm, the fan diameter is 50 mm, the maximum rotational speed of the motor 4 is 63,000 rpm, and the fan 6 has three stages. The air volume of the air duster 1 measured according to Japanese Industrial Standards (JIS B8330) is approximately 0.36 m ³ /s, the wind velocity is approximately 212 m/s, and the pressure is approximately 26.6 kPa. The air duster 1 can be said to be a multi-stage centrifugal blower with a relatively small air volume and high pressure.

As described above, in the air duster 1 of the present embodiment, the nozzle diameter and the fan diameter are selected within the ranges described above, and the diameters of the nozzle 231 and the fan 6 are reduced. can be On the other hand, the decrease in the wind force due to the smaller diameters of the nozzle 231 and the fan 6 is suppressed by selecting the maximum rotation speed of the motor 4 within the range described above and setting it relatively high. In this way, by setting the specifications within the above range, a relatively small electric multistage blower capable of generating wind power capable of blowing away dust and the like is realized.

Moreover, in this embodiment, the motor 4 is a brushless motor. The controller 331 is configured to control the rotation speed of the motor 4 according to the amount of operation of the trigger 311 . Therefore, the user can adjust the number of revolutions and thus the wind force according to the operation of the trigger 311 . Further, the air duster 1 is a hand-held blower that can be used by the user while gripping the handle 3 (gripping portion 31) and pulling the trigger 311, which is highly convenient.

Correspondence between each component of the above embodiment and each component of the present invention is shown below. The air duster 1 is an example of the "blower" of the present invention. The motor 4 is an example of a "motor." Fan 6 is an example of a "centrifugal fan." The rotation axis A1 is an example of a "rotation axis". The body housing 2, the suction port 201, and the discharge port 203 are examples of "housing," "suction port," and "discharge port," respectively. The partition plate 71 (each of the first partition plate 711, the second partition plate 712, and the third partition plate 713) is an example of the "partition plate." Vent 710 is an example of a "vent." Each of the first region R1, the second region R2, and the third region R3 is an example of "regions corresponding to fans." The straightening member 73 is an example of a "straightening member". The backboard 631 is an example of a "backboard." The rear surface and front surface of the back plate 631 are examples of the "first surface" and the "second surface", respectively. The wing 633 is an example of a 'wing'. The base plate 731 is an example of a “base plate”. The rear surface and front surface of the base plate 731 are examples of the "third surface" and the "fourth surface", respectively. Guide vane 735 is an example of a "protrusion" and a "guide vane." The straightening member 75 is an example of a "final straightening member". The stator 41 and rotor 43 are examples of "stator" and "rotor", respectively.

Note that the above-described embodiment is merely an example, and the blower according to the present invention is not limited to the air duster 1 illustrated. For example, the modifications exemplified below can be made. It should be noted that any one of these modifications, or a plurality thereof, may be employed in combination with the air duster 1 shown in the embodiment or with the inventions described in each claim.

For example, the power source of the air duster 1 is not limited to the rechargeable battery 340, and may be a disposable battery or an external AC power source. Also, the air duster 1 may incorporate a rechargeable battery. Alternatively, the motor 4 may be a motor having brushes.

The number of fans 6 (that is, the number of stages) is not limited to three as illustrated, and may be two or four or more. The number of fans 6 can be appropriately selected according to the wind force required for the air duster, for example.

The configuration of the fan 6 can also be changed as appropriate. For example, the type of fan 6 need not be the illustrated open rearward fan, but may be a centrifugal fan with other configurations (e.g., closed rearward fan, radial fan, multi-blade fan). . The size and shape of the back plate 631 and the number, size, shape and arrangement of the blades 633 can be changed as appropriate. Further, the fan 6 may be entirely integrated or partly integrated instead of being configured by a plurality of members that are connected and fixed to each other. Moreover, all of the plurality of fans 6 do not necessarily have the same structure.

Also, the fan 6 does not necessarily have to be fastened to the motor shaft 45 by the nut 81, and for example, each may be press-fitted onto the motor shaft 45 and fixed. Further, instead of the motor shaft 45, the fan 6 may be fastened or press-fitted to another rotating shaft that is driven to rotate as the motor 4 is driven.

The partition structure 7 is arranged between the plurality of fans 6 in the direction of the rotation axis A1, and partitions the interior of the main body housing 2 into a plurality of regions corresponding to the fans 6, the number of which is the same as in the above embodiment. Not limited. Specifically, the number of partition structures 7 is determined according to the number of fans 6, and is 1 when the number of fans 6 is 2, and is plural when the number of fans 6 is 3 or more (more than the number of fans 6). 1 less number).

The configuration of the partition structure 7 can also be changed as appropriate. In the above embodiment, the partition structure 7 includes the straightening member 73 and the partition plate 71 formed as separate members, but the straightening member 73 and the partition plate 71 are a single member formed integrally. may When a plurality of partition structures 7 are provided, not all partition structures 7 (that is, partition plates 71 and rectifying members 73) need to have the same structure.

In the above embodiment, the spacer 77 is formed separately from the partition structure 7 and fastened to the main body housing 2 together with the partition structure 7 for positioning the partition structure 7 in the direction of the rotation axis A1 (front-rear direction). However, for example, the first-stage and second-stage spacers 77 may be integrated with the same-stage rectifying member 73, respectively, or the same-stage rectifying member 73 and the next-stage (front) section may be integrated with each other. It may be integrated with the plate 71 (second partition plate 712, third partition plate 713). Alternatively, the spacer 77 may be integrated with the partition plate 71 (first partition plate 711, second partition plate 712) on the front side (rear side). Similarly, the third-stage spacer 77 may be integrated with the rectifying member 75, or may be integrated with the front-stage (rear) partition plate 71 (third partition plate 713). Note that the straightening member 75 arranged between the final-stage fan 6 and the discharge port 203 may be omitted.

The individual configurations of the partition plate 71, the rectifying members 73 and 75, and the spacer 77 are not limited to those illustrated in the above embodiment. For example, the size and shape of the base plate 731 of the straightening member 73 can be changed as appropriate. For example, the base plate 731 may have an outer diameter that is larger or smaller than the outer diameter of the back plate 631 of the fan 6 . Also, the number, size, shape, arrangement, and orientation of the guide vanes 735 and 753 of the rectifying members 73 and 75 can be changed as appropriate. For example, the radially outer ends of the guide vanes 735 may be co-located with the outer edge of the base plate 731 . Further, in the above embodiment, the ribs 211 of the main body housing 2 receive the first partition plate 711 , but the portion of the main body housing 2 that receives the partition structure 7 or the intervening member is a portion other than the ribs 211 . may

In the above embodiment, the fan 6 is fastened to the motor shaft 45 by a single nut 81 that is screwed and fixed to the motor shaft 45, and the partition plate 71, the rectifying members 73 and 75, and the spacer 77 are the main body. It is fastened to the housing 2 . However, the partition plate 71 and the straightening members 73 and 75 may be fixed to the main body housing 2 independently of the fan 6 . In this case, the spacer 77 can be omitted. The method of fixing the partition plate 71 and the rectifying members 73 and 75 is not limited to fastening as in the above embodiment. For example, when the main body housing 2 is composed of two half-split bodies that are divided along a plane parallel to the rotation axis A1, the partition plate 71 may be formed integrally with the main body housing 2, or the rectifying member 73 and 75 may be held by ribs provided inside the body housing 2 .

The configuration of the body housing 2 and the layout of the internal structure can be changed as appropriate. For example, the shape of the main body housing 2 (cylindrical portion 21) may be changed to a rectangular cylindrical shape instead of a cylindrical shape. The size, shape, arrangement, etc. of the suction port 201 and the discharge port 203 may be changed as appropriate from the example of the above embodiment. Further, for example, the motor 4 may be arranged between the final-stage fan 6 and the discharge port 203 instead of between the suction port 201 and the first-stage fan 6 . The structure of the handle 3 can also be changed as appropriate. Also, instead of the handle 3, a part of the body housing 2 may have a grip portion that is gripped by the user.

In the above-described embodiment, the number of rotations of the motor 4 can be changed steplessly according to the amount of operation of the trigger 311, but it may not be possible to change the number of rotations from a predetermined number of rotations, or it may be changed in a plurality of steps. may be For example, the air duster 1 may be configured such that the number of revolutions of the motor 4 can be set in a plurality of stages by operating the operation section 333 (push button). In this case, the controller 331 may control the number of revolutions of the motor 4 according to the signal output from the operation section 333 . Further, as the operation member through which the setting of the number of rotations of the motor 4 can be input, a dial, a touch panel, etc. can be employed in addition to the trigger 311 and push buttons. The controller 331 may be composed of other types of control circuits instead of a microcomputer.

The numerical values of the specifications (wind force, nozzle diameter, fan diameter, maximum rotation speed, air volume, wind speed, pressure, etc.) given in the above embodiment are merely examples, and different numerical values may be adopted. The same applies to the materials of the body housing 2, the fan 6, the partition plate 71, the rectifying members 73 and 75, the spacer 77, and the like.

Furthermore, the following aspects are constructed in view of the spirit of the present invention, the above-described embodiments, and modifications thereof. Any one of the following aspects, or a plurality thereof, can be employed in combination with the air duster 1 shown in the embodiment and the above modification, or the invention described in each claim.

[Aspect 1]
The second surface of the back plate and the third surface of the base plate are both flat surfaces and are arranged parallel to each other.

[Aspect 2]
a rotary shaft configured to rotate around the rotary shaft as the motor is driven;
a single fastening member configured to fasten the plurality of fans to the rotating shaft and to fasten the plurality of partition plates and the at least one straightening member to the housing. there is
The motor shaft 45 and the nut 81 of the above embodiment are examples of the "rotating shaft" and the "fastening member" in this aspect, respectively.
According to this aspect, in assembling the blower, the operation of assembling the plurality of fans to the rotating shaft and the operation of assembling the partition plate and the rectifying member to the housing can be performed at once using a single fastening member. . Therefore, according to this aspect, a multi-stage centrifugal fan that is even more easily assembled is realized.

[Aspect 3]
further comprising a bearing that includes a first portion and a second portion configured to be relatively rotatable, and supports the rotating shaft to be rotatable about the rotation axis with respect to the housing;
The fastening member fastens the plurality of fans to the rotating shaft via the first portion, and fastens the plurality of partition plates and the at least one straightening member to the housing via the second portion. configured to fasten to the
The bearing 46, the inner ring 463, and the outer ring 461 of the above embodiment are examples of the "bearing,""firstportion," and "second portion," respectively, in this aspect.

[Aspect 4]
the motor includes a stator held by the housing, a rotor disposed inside the stator, and an output shaft to which the rotor is fixed;
The rotating shaft is the output shaft.
The stator 41, rotor 43, and motor shaft 45 of the above embodiment are examples of the "stator,""rotor," and "output shaft" in this aspect, respectively.

1: air duster, 2: body housing, 201: suction port, 203: discharge port, 21: cylindrical portion, 211: rib, 212: front end surface, 23: front cover, 231: nozzle, 25: rear cover, 251 : Rib 255: Bearing holding portion 256: Retainer 29: Screw 3: Handle 31: Grip portion 311: Trigger 313: Switch 33: Controller housing portion 331: Controller 333: Operation portion 34 : battery mounting part, 340: battery, 4: motor, 40: body part, 41: stator, 43: rotor, 431: balance ring, 45: motor shaft, 451: flange, 453: male screw part, 455: fan attachment Part 46: Bearing 461: Outer ring 463: Inner ring 47: Bearing 471: Outer ring 473: Inner ring 6: Fan 601: First fan 602: Second fan 603: Third fan 61: Hub, 610: Sleeve, 612: Large diameter portion, 613: Flange, 614: Small diameter portion, 63: Main body, 631: Back plate, 632: Protrusion, 633: Blade, 635: Boss, 65: Locking member, 651: Boss , 653: flange, 654: concave portion, 7: partition structure, 71: partition plate, 710: vent, 711: first partition plate, 712: second partition plate, 713: third partition plate, 73: rectifying member, 731: base plate, 732: protruding portion, 733: through hole, 735: guide vane, 75: straightening member, 751: cylindrical portion, 753: guide vane, 755: bearing holding portion, 756: through hole, 77: spacer, 81: nut, 83: locking nut, 89: washer, R1: first region, R2: second region, R3: third region

Claims (9)

a blower,
a motor;
A plurality of rollers arranged coaxially in multiple stages, each rotating around a predetermined rotating shaft in accordance with the driving of the motor, sucking air in the axial direction of the rotating shaft and sending it radially outward. centrifugal fan of
A housing that accommodates the motor and the plurality of centrifugal fans, and has an intake port for sucking air into the housing and a discharge port for discharging the air that has been compressed and sent out by the plurality of centrifugal fans. a housing having
a plurality of compartments arranged on the suction side of each of the plurality of centrifugal fans in the axial direction, defining boundaries of areas corresponding to the respective centrifugal fans, and each having a vent provided on the rotating shaft; a board;
at least one straightening member disposed between the plurality of centrifugal fans in the axial direction;
Each of the plurality of centrifugal fans
a disk-shaped back plate having a suction-side first surface and a second surface opposite to the first surface;
A plurality of blades protruding from the first surface,
each of the at least one rectifying member,
a disk-shaped base plate arranged to face the second surface of the back plate and having a third surface facing the second surface and a fourth surface opposite to the third surface;
a plurality of protrusions protruding from the base plate and configured to guide air flow in a specific direction;
The plurality of protrusions are provided only on the fourth surface of the base plate, and are a plurality of guides for guiding the flow of air toward the vent of the partition plate corresponding to the centrifugal fan of the next stage. Constructed as wings,
each of the plurality of guide vanes protrudes radially outward from the base plate and reaches the inner surface of the housing ;
The blower is
a rotary shaft configured to rotate around the rotary shaft as the motor is driven;
a single fastening member configured to fasten the plurality of fans to the rotating shaft and to fasten the plurality of partition plates and the at least one flow straightening member to the housing. A blower characterized by: The fan according to claim 1,
further comprising a bearing that includes a first portion and a second portion configured to be relatively rotatable, and supports the rotating shaft to be rotatable about the rotation axis with respect to the housing;
The fastening member fastens the plurality of fans to the rotating shaft via the first portion, and fastens the plurality of partition plates and the at least one straightening member to the housing via the second portion. A blower configured to be fastened to a The fan according to claim 1 or 2,
the motor includes a stator held by the housing, a rotor disposed inside the stator, and an output shaft to which the rotor is fixed;
A blower, wherein the rotating shaft is the output shaft of the motor. The fan according to any one of claims 1 to 3 ,
The blower, wherein the plurality of guide vanes are arranged so that their radially outer ends are inclined in a direction opposite to the direction of rotation of the centrifugal fan. The fan according to any one of claims 1 to 4 ,
The blower, wherein the plurality of blades are arranged so that their radially outer ends are inclined in a direction opposite to the direction of rotation of the centrifugal fan. The fan according to any one of claims 1 to 5 ,
A fan, wherein the back plate and the base plate have the same outer diameter. The fan according to any one of claims 1 to 6 ,
a final rectifying member disposed between a final-stage centrifugal fan and the discharge port among the plurality of centrifugal fans, and configured to direct air sent from the final-stage centrifugal fan toward the discharge port; A blower, further comprising: The fan according to any one of claims 1 to 7 ,
An air blower, wherein the plurality of partition plates and the at least one straightening member are configured as separate members. The fan according to any one of claims 1 to 8 ,
A blower according to claim 1, wherein the stator and rotor of the motor are arranged between the suction port and a first stage centrifugal fan among the plurality of centrifugal fans.

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