JP5630143B2 - Centrifugal fan and self-propelled robot equipped with centrifugal fan - Google Patents

Description

  The present invention relates to a centrifugal fan that sucks in an axial direction and exhausts in a radial direction, and a self-propelled cleaning robot equipped with the centrifugal fan.

In recent years, fans have been used not only for cooling electronic devices but also for applications that require a suction force to suck in air, such as self-propelled cleaning robots. When a fan is used for cooling an electronic device, the fan is required to be downsized as the electronic device is downsized. The same applies to a fan used for suction. In order to achieve downsizing of the fan, it is necessary to accommodate a motor composed of a rotor magnet and an armature radially inward of the blades. For example, Patent Document 1 discloses the above-described structure.
JP 2006-029312 A

  However, in the fan, not only miniaturization but also high static pressure and high air volume are required. Similarly, a high static pressure and a high air volume are required for the suction fan. In the fan, when the static pressure characteristic is improved, the air flow characteristic is lowered, and when the air flow characteristic is improved, the static pressure characteristic is lowered. That is, the static pressure characteristic and the air volume characteristic are in a trade-off relationship. That is, a fan that improves the static pressure characteristics without reducing the air flow characteristics is required.

  A first invention of the present application is a shaft disposed coaxially with a central axis, a rotor hub that is fixed to the shaft and has a substantially cylindrical shape with a lid, and is arranged in a circumferential direction with respect to the shaft. A plurality of blades erected upward in the direction, a substantially annular rotor magnet fixed to the inner peripheral surface of the rotor hub, an armature opposed to the magnet in a radial direction, and a radial direction from the armature And a bearing mechanism that rotatably supports the shaft, and the outer peripheral surface of the rotor hub has an inclined surface that is inclined downward in the axial direction as it goes radially outward. The radially inner end of the connecting portion between the blade and the rotor hub is located on the inclined surface, and a shaft is formed between the radially inner edge and the axial upper edge of the blade toward the radially inner side. Direction downward A centrifugal fan inclined edges obliquely is formed.

  According to the present invention, high air volume and high static pressure can be improved while achieving miniaturization.

FIG. 1 is a longitudinal sectional view of a centrifugal fan. FIG. 2 is a plan view of the stator core in plan view. FIG. 3 is a perspective view of the impeller. FIG. 4 is a cross-sectional view showing a centrifugal fan mounted on a self-propelled cleaning robot.

  In the present specification, the upper side in the central axis direction of the centrifugal fan 1 is simply referred to as “upper side”, and the lower side is simply referred to as “lower side”. The vertical direction in the description of the present invention does not indicate the positional relationship or direction when incorporated in an actual device. The radial direction centered on the central axis is simply referred to as “radial direction”, and the circumferential direction centered on the central axis is simply referred to as “circumferential direction”.

(Embodiment as centrifugal fan)
FIG. 1 is a longitudinal sectional view of the centrifugal fan 1. The centrifugal fan 1 includes a stationary part 2, a bearing mechanism 3, and a rotating part 4 that is a rotating assembly. The impeller 10 is a part of the rotating unit 4. The rotating part 4 is positioned above the stationary part 2 and the bearing mechanism 3, and is supported by the bearing mechanism 3 so as to be rotatable about a central axis J <b> 1 that faces the stationary part 2 in the vertical direction. The impeller 10 is provided on the upper portion of the rotating unit 4.

  The stationary part 2 includes a base part 21, an armature 22, and a circuit board 24. A cylindrical bearing holder 211 is provided at the center of the base portion 21. The bearing mechanism 3 is attached in the bearing holder 211. The armature 22 is provided outside the bearing mechanism 3 in the radial direction. The armature 22 includes a stator core 221 and a plurality of coils 222. Stator core 221 is formed by laminating steel plates. Referring to FIG. 2, coil 222 is formed by being wound around each tooth 2212 of stator core 221. The circuit board 24 is disposed on the base portion 21.

  The bearing mechanism 3 includes a shaft 31, a bottomed substantially cylindrical bush 32, a sleeve 33, and a thrust plate 34. The bush 32 is fixed to the bearing holder 211. Lubricating oil is held inside the bush 32.

  The sleeve 33 is formed of an oil-containing porous sintered metal body and is fixed in the bush 32 by press fitting. A thrust plate 34 is disposed on the bottom of the bush 32. The shaft 31 is inserted into the sleeve 33. When the shaft 31 rotates, the shaft 31 is supported by the sleeve 33 in the radial direction via the lubricating oil. Further, the lower end of the shaft 31 abuts on the thrust plate 34, so that the shaft 31 is stably supported in the thrust direction.

  In the vicinity of the lower end of the shaft 31, an annular reduced diameter portion 311 that is recessed inward in the radial direction is formed. An annular retaining member 35 is disposed below the lower end surface of the sleeve 33. The inner diameter of the through hole formed at the center of the retaining member 35 is smaller than the outer diameter of the shaft 31 and larger than the outer diameter of the reduced diameter portion 311. The retaining member 35 is at the same position as the reduced diameter portion 311 in the axial direction. Therefore, the retaining member 35 prevents the shaft 31 from moving upward in the axial direction.

  The rotating unit 4 includes a lid-shaped substantially cylindrical rotor holder 41, a rotor magnet 42, and an impeller 10. The rotor holder 41 is made of a magnetic material. The rotor holder 41 includes a lid portion 411, a cylindrical portion 412, and a cylindrical shaft fixing portion 413. The lid portion 411 has a disk shape substantially perpendicular to the central axis J1.

  The cylindrical portion 412 extends downward from the outer periphery of the lid portion 411. A rotor magnet 42 is attached to the inner side surface of the cylindrical portion 412. The rotor magnet 42 faces the armature 22 in the direction perpendicular to the central axis J1, that is, in the radial direction. When the centrifugal fan 1 is driven, a rotational force due to a magnetic action is generated between the rotor magnet 42 and the armature 22. The shaft fixing portion 413 is located at the center of the lid portion 411. The upper portion of the shaft 31 is fixed to the shaft fixing portion 413.

  FIG. 3 is a perspective view of the impeller 10. Referring to FIGS. 1 and 3, impeller 10 is formed by injection molding using a resin, and includes cup portion 101, blade fixing portion 102, and a plurality of blades 103. The cup part 101 includes a lid part 1011 and a cylindrical part 1012. Moreover, the cup part 101 is arrange | positioned in the aspect which encloses the rotor holder 41 in radial direction outward and axial direction upper direction. A portion where the rotor holder 41, the cup portion 101, and a blade fixing portion 102 described later are integrated is referred to as a rotor hub 40. The blade fixing portion 102 extends outward in the radial direction and downward in the axial direction from the vicinity of the boundary between the lid portion 1011 and the cylindrical portion 1012 of the cup portion 101. At this time, the upper surface of the blade fixing portion 102 is an inclined surface 1021 that is inclined downward in the axial direction toward the outer side in the radial direction. The inclined surface 1021 is a concave surface that is recessed inward in the radial direction. In other words, the inclined surface 1021 has a smaller inclination angle with respect to the axial direction as it goes radially inward. In the present embodiment, the inclined surface 1021 is a curved surface.

  The blade 103 extends from the blade fixing portion 102 upward in the axial direction. At that time, the radially inner edge 1031 of the blade 103 is located on the inclined surface 1021. The radially inner edge 1031 is formed substantially parallel to the central axis J1. Further, the radial outer edge 1032 of the blade 103 is located radially outward from the blade fixing portion 102. That is, the blade 103 protrudes outward in the radial direction from the blade fixing portion 102. An inclined edge 1034 is formed between the upper edge 1033 of the blade 103 and the radially inner edge 1031, which is inclined downward in the axial direction as it goes radially inward. The inclined edge 1034 is a concave surface that is recessed outward in the radial direction. In other words, the inclination angle of the inclined edge 1034 with respect to the axial direction decreases as it goes radially outward. In the present embodiment, the inclined edge 1034 is a curved surface. The center of the radius of curvature of the curved surface is located above the upper surface of the lid portion 1011 of the cup portion 101 in the axial direction. As shown in FIG. 3, the plurality of blades 103 are connected by an annular ring 104 on the radially outer side of the upper edge 1033 of the blade 103. Thereby, the vibration of the blades 103 can be reduced and the rigidity of the blades 103 can be increased.

  Next, an air flow generated when the impeller 10 rotates will be described. When the impeller 10 rotates, the air staying in the vicinity of the blades 103 is discharged radially outward by centrifugal force. As a result, the vicinity of the blade 103 is in a negative pressure state, and air positioned upward in the axial direction is sucked toward the blade 103.

  More specifically, the air located in the upper axial direction near the upper end of the blade fixing portion 102 moves downward along the axial direction in accordance with the above-described action. Thereafter, the air moves radially outward along the inclined surface 1021 of the blade fixing portion 102. Air approaching the radially inner edge 1031 of the blade 103 is pushed outward in the radial direction by the centrifugal force generated by the rotational action of the blade 103. However, since the air flow before reaching the blade 103 has a vector directed downward in the axial direction, the air has a diameter from the blade 103 along the inclined surface 1021 due to the sum of the inertial force and centrifugal force vectors. Exhaled in the direction outward.

  Assuming that the radially inner edge 1031 of the blade 103 is located at the upper end of the inclined surface 1021, the air moved downward along the axial direction directly hits the lid 1011 of the cup 101 and is directed downward in the axial direction. Lose the flow vector. Along with this, the air sucked toward the blade 103 is pushed outward in the radial direction by a strong vector component flow toward the radially outer side when it reaches the radially inner edge 1031 of the blade 103. Therefore, in the vicinity of the connection portion between the blade 103 and the blade fixing portion 102, it is difficult to contribute to the extrusion of air. For this reason, when the impeller 10 rotates, the windage loss becomes large, and the efficiency is poor in the airflow characteristics. Therefore, the embodiment in which the radially inner edge 1031 of the blade 103 is positioned at the uppermost end of the inclined surface 1021 is not preferable because the efficiency of the air flow characteristic is poor. In the present embodiment, the radially inner edge 1031 of the blade 103 is positioned substantially at the center of the inclined surface 1021 in the axial direction.

  The air located in the upper axial direction near the upper part of the inclined edge 1034 of the blade 103 moves downward along the axial direction. After that, the air approaching the inclined edge 1034 of the blade 103 enters the inclined edge 1034 in a state where a lot of vector components remain in the axial direction, unlike the flow of air approaching the vicinity of the radially inner edge 1031. . Thus, the air that passes through the inclined edge 1034 and is pushed outward in the radial direction has a vector component of a flow directed downward in the axial direction.

  In the present embodiment, the lower end portion of the inclined edge 1034 is positioned below the top surface of the lid portion 1011 of the cup portion 101 in the axial direction. This is because the armature 22 is composed of three phases, so that the axial thickness is thinner than the single phase or the two phases. This will be described in more detail below. FIG. 2 is a plan view of the stator core 221 in plan view. Stator core 221 includes a core back 2211 and a plurality of teeth 2212. In the present embodiment, the number of teeth 2212 is nine. A U-phase coil 222 is wound around three of the plurality of teeth 2212, and a V-phase and W-phase coil 222 is wound around each of the remaining three teeth 2212. The number of teeth 2212 is not limited as long as a plurality of teeth 2212 is a multiple of 3 and three-phase coils 222 of U phase, V phase, and W phase are wound.

  As a result, both the air entering the radially inner edge 1031 of the blade 103 and the air entering the inclined edge 1034 of the blade 103 have a vector component of the flow downward in the axial direction. Therefore, air is discharged radially outward without stagnation. In addition, since the top surface of the lid portion 1011 of the cup portion 101 is formed low, the air discharged radially outward by the rotation of the impeller 10 can pass through the upper portion of the lid portion 1011. The air volume increases. The air passing through the upper portion of the lid portion 1011 moves radially outward along the upper surface of the lid portion 1011. At this time, it is pushed by the air flowing from above and flows downward along the inclined surface 1021 in the axial direction. The flow rate of the air that passes through the blades 103 and is pushed outward in the radial direction, that is, the air volume, is much lower in the axial direction, and the air volume decreases as it goes upward in the axial direction. In other words, in order to improve the air flow characteristics, it is important how to use the region below the axial direction of the blade 103. By applying the present invention, a region below the axial direction of the blade 103 can be utilized. When the lid portion 1011 of the cup portion 101 is formed at a position that is significantly higher than that of the embodiment, that is, the radial inner edge 1031 of the blade 103 is formed at a position that is significantly lower than the middle of the inclined surface 1021 in the axial direction. In this case, the region below the axial direction of the blade 103 cannot be fully utilized.

  As a modification, the radial inner edge 1031 of the blade 103 may be inclined radially inward as it goes downward in the axial direction. However, the angle with respect to the central axis needs to be smaller than the inclined edge 1034. Further, the cup portion 101 may be formed in a cylindrical shape instead of a cup shape, and the lid portion 411 of the rotor holder may be exposed upward. Furthermore, a through hole may be formed in the center of the lid surface 1011 of the cup part 101, and the cup part 101 may be directly fixed to the shaft 31 by inserting the shaft 31 into the through hole. In addition, about a modification, if it has the basic composition of this invention, it can change suitably.

(Embodiment as a self-propelled cleaning robot)
FIG. 4 is a cross-sectional view showing the centrifugal fan 1 mounted on the self-propelled cleaning robot 5. The self-propelled cleaning robot 5 can be self-propelled by a wheel 51 attached to the main body 50. The self-propelled cleaning robot 5 is controlled so as to change the traveling direction by contacting an obstacle or the like. In the self-propelled cleaning robot 5, a first air inlet 52 that sucks in wind generated when the centrifugal fan 1 is driven is formed on the bottom surface side. Air sucked from the first air inlet 52 passes through the filter 53. At this time, air is sucked together with the dust, only the dust adheres to the filter 53, and the air passes through the filter 53. Thereafter, the air passes through the second intake port 54 formed on the upper side in the axial direction of the impeller 10 of the centrifugal fan 1. Thereafter, the air is exhausted toward the exhaust port by the impeller 10. The exhaust port is not shown.

  The inner diameter of the second air inlet 54 is formed larger than the inner diameter of the radially inner edge 1031 of the blade 103. That is, the inner diameter of the second air inlet 54 overlaps the upper edge 1033 of the blade 103 when viewed in a direction parallel to the axial direction. It is desirable that the air flow immediately after passing through the second air inlet 54 be parallel to the central axis J1. Thereby, it is possible to achieve the air volume characteristic and the static pressure characteristic of the centrifugal fan 1 described above.

  When the inner diameter of the second air inlet 54 is smaller than the radially inner edge 1031 of the blade 103, the air flow changes radially outward toward the blade 103 after passing through the second air inlet 54. As a result, since the flow of the axial component of air is lost, the region below the axial direction of the blade 103 cannot be utilized.

  The present invention is used as a centrifugal fan for blowing and exhausting air. In particular, it is used for self-propelled cleaning robots for intake.

DESCRIPTION OF SYMBOLS 1 Centrifugal fan 2 Static part 3 Bearing mechanism 4 Rotating part 10 Impeller 22 Armature 31 Shaft 41 Rotor holder 42 Rotor magnet 102 Blade fixed part 103 Blade 1021 Inclined surface 1031 Radial inner edge 1034 Inclined edge J1 Central axis

Claims (6)

A shaft arranged coaxially with the central axis;
A rotor hub fixed to the shaft;
A plurality of blades arranged in a circumferential direction with respect to the shaft, and erected upward in the axial direction from the rotor hub;
A substantially annular rotor magnet fixed to the inner peripheral surface of the rotor hub;
An armature radially opposed to the magnet;
A bearing mechanism disposed radially inward from the armature and rotatably supporting the shaft;
With
The rotor hub includes a lid-shaped substantially cylindrical rotor holder fixed to the shaft, a cup portion having a lid portion and a cylindrical portion, and enclosing the rotor holder radially outward and axially upward; A blade fixing portion that extends from the vicinity of the boundary between the lid portion and the cylindrical portion and that is positioned on the radially outer side of the cylindrical portion and on which the plurality of blades are erected,
The outer peripheral surface of the blade fixing portion has an inclined surface that is inclined downward in the axial direction as it goes radially outward, and the radially inner end of the connecting portion between the blade and the blade fixing portion is A centrifugal fan that is located on an inclined surface and has an inclined edge that is inclined downward in the axial direction as it goes inward in the radial direction between the radially inner edge and the axially upper edge of the blade. The centrifugal fan according to claim 1, wherein the lower end in the axial direction of the inclined edge is positioned below the upper surface of the cup portion in the axial direction.   The centrifugal fan according to claim 1, wherein the inclined edge is a concave surface that is recessed outward in the radial direction. The centrifugal fan according to any one of claims 1 to 3, wherein an outer peripheral surface of the blade fixing portion is a concave surface that is recessed inward in the radial direction. The centrifugal fan according to any one of claims 1 to 4 further includes a substantially circular air inlet, and an inner diameter of the air inlet is larger than a radially inner edge of the blade. A centrifugal fan according to claim 5 ;
A main body for housing the centrifugal fan;
A wheel for self-propelling the main body;
An air inlet formed in the lower surface of the main body,
A filter disposed between the air inlet and the centrifugal fan;
Self-propelled cleaning robot with

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