Electric blower

Abstract

This electric blower comprises: an electric motor including a rotor having a rotary shaft; and a rotary fan attached to the rotary shaft. The rotary fan includes a plurality of fan blades. With regard to the plurality of fan blades, when the pitch is θp, the maximum deviation angle is m, the order is n (n is an integer of 1 or more), and the blade number is a, an inter-blade angle θ of the fan blade having the blade number a satisfies formula (1).

Description

electric blower

[0001] The present disclosure relates to an electric blower having a rotating fan.

[0002] Electric blowers with rotary fans are used in a variety of products, such as electric vacuum cleaners. The electric blowers installed in electric vacuum cleaners use centrifugal fans as the rotary fans, which can generate high suction pressure.

[0003] A rotary fan is attached to the rotating shaft of an electric motor mounted on an electric blower, and generates a desired wind pressure by rotating at high speed. Conventionally, a rotary fan having multiple fan blades aligned in the rotation direction has been known (see, for example, Patent Document 1).

[0004] In a conventional rotary fan, a plurality of fan blades are arranged at equal intervals in the direction of rotation.

[0005] However, if multiple fan blades are arranged at equal intervals, noise peaks occur at specific frequencies (e.g., multiples of the number of fan blades) when the rotary fan rotates, making the noise generated by the entire electric blower very harsh.

[0006] Japanese Patent Application Laid-Open No. 2000-310197

[0007] The present disclosure has been made to solve these problems, and aims to provide an electric blower that can reduce noise peaks at specific frequencies that occur when the rotary fan rotates.

[0008] In order to achieve the above object, an electric blower according to one aspect of the present disclosure includes an electric motor including a rotor having a rotating shaft, and a rotary fan attached to the rotating shaft, wherein the rotary fan has a plurality of fan blades, and where, for the plurality of fan blades, θp has a pitch, m has a maximum deviation angle, n has an order (n is an integer greater than or equal to 1), and the blade number is a, the inter-blade angle θ of the fan blade with blade number a satisfies the following (Equation 1):

[0009]

[0010] According to another aspect of the present disclosure, there is provided an electric blower comprising: an electric motor including a rotor having a rotary shaft; a rotary fan attached to the rotary shaft; and an air guide section positioned opposite the rotary fan and into which air discharged from the rotary fan flows, the air guide section having a plurality of diffuser vanes, wherein, in the plurality of diffuser vanes, when a pitch is αp, a maximum deviation angle is j, an order is k (k is an integer equal to or greater than 1), and a vane number is b, the inter-blade angle α of the guide vane having vane number b satisfies the following (Equation 2):

[0011]

[0012] According to the electric blower according to the present disclosure, it is possible to reduce noise peaks at specific frequencies when the rotary fan rotates.

[0013] FIG. 1 is an external perspective view of an electric blower according to an embodiment. FIG. 2 is an exploded perspective view of the electric blower according to an embodiment. FIG. 3 is a cross-sectional view of the electric blower according to an embodiment. FIG. 4 is an exploded perspective view of the electric blower according to an embodiment with the fan case and the rotary fan removed. FIG. 5 is an exploded perspective view of the rotary fan in the electric blower according to an embodiment. FIG. 6 is a plan view of the rotary fan (where n = 1) with the first fan plate removed. FIG. 7 is a plan view of the rotary fan (where n = 2) with the first fan plate removed. FIG. 8 is a graph showing the relationship between the blade numbers of the 11 fan blades and the inter-blade angle in the rotary fan of the electric blower according to an embodiment. FIG. 9 is a table showing specific values ​​showing the relationship between the blade numbers of the 11 fan blades and the inter-blade angle in the rotary fan of the electric blower according to an embodiment. FIG. 10 is a graph showing the relationship between the blade numbers of the 16 fan blades and the inter-blade angle in the rotary fan of the electric blower according to an embodiment. FIG. 11 is a table showing specific numerical values ​​indicating the relationship between the blade numbers of the fan blades (total number = 16) and the inter-blade angles in the rotary fan of the electric blower according to the embodiment.

[0014] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Each of the embodiments described below represents a specific example of the present disclosure. Therefore, the numerical values, shapes, materials, components, arrangement positions and connection forms of the components, etc. shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Therefore, among the components in the following embodiments, components that are not recited in the independent claims will be described as optional components.

[0015] In this specification and the drawings, the X-axis, Y-axis, and Z-axis represent the three axes of a three-dimensional Cartesian coordinate system. The X-axis and Y-axis are perpendicular to each other and perpendicular to the Z-axis. In this embodiment, the Z-axis direction is the direction in which the axis C of the rotation shaft 11a extends.

[0016] Each drawing is a schematic diagram and is not necessarily a precise illustration. In all drawings, substantially the same components are denoted by the same reference numerals, and redundant explanations will be omitted or simplified.

[0017] In this embodiment, the radial direction of the rotor 11 and the stator 12 is referred to as the "radial direction," and the rotation direction of the rotor 11 is referred to as the "circumferential direction." In other words, the direction extending from the axis C of the rotating shaft 11a around the axis C is referred to as the "radial direction," and the direction circumferentially around the axis C of the rotating shaft 11a around the axis C is referred to as the "circumferential direction." Therefore, the "radial direction" is a direction perpendicular to the direction of the axis C of the rotating shaft 11a (also simply referred to as the "axial direction"). In this specification, the terms "up" and "down" do not necessarily refer to the up direction (vertically upward) and the down direction (vertically downward) in absolute spatial recognition. For convenience, in this specification, the direction in which the axis C of the rotating shaft 11a extends is referred to as the up-down direction.

[0018] (Embodiment) First, the overall configuration of an electric blower 1 according to an embodiment will be described with reference to Figures 1 to 4. Figure 1 is an external perspective view of the electric blower 1 according to an embodiment. Figure 2 is an exploded perspective view of the electric blower 1 according to an embodiment. Figure 3 is a cross-sectional view of the electric blower 1 according to an embodiment. Figure 3 shows a cross-section taken along a plane passing through the axis C of the rotary shaft 11a and the brush 16. The thick arrows shown in Figure 3 indicate the main flow of air sucked into the electric blower 1. Figure 4 is an exploded perspective view of the electric blower 1 according to an embodiment with the fan case 40 and rotary fan 20 removed.

[0019] As shown in Figures 1 to 4, the electric blower 1 of this embodiment includes an electric motor 10, a rotary fan 20, an air guide section 30, a fan case 40, and a motor case 50. The rotary fan 20 is attached to a rotary shaft 11a of the electric motor 10. Air discharged from the rotary fan 20 flows into the air guide section 30. The fan case 40 covers the rotary fan 20 and the air guide section 30. The motor case 50 houses the electric motor 10. The electric blower 1 can be used in, for example, an electric vacuum cleaner. The motor case 50 is also referred to as a second bracket.

[0020] The electric motor 10 is a fan motor that rotates the rotary fan 20. As an example, the electric motor 10 is a DC motor that receives a DC power supply as an input. In this embodiment, the electric motor 10 is a commutator motor with brushes.

[0021] Specifically, the electric motor 10 includes a rotor 11 , a stator 12 , a first bearing 13 , a second bearing 14 , a commutator 15 , and brushes 16 .

[0022] The rotor 11 has a rotating shaft 11a. The rotor 11 rotates around the axis C of the rotating shaft 11a due to the magnetic force of the stator 12. The rotor 11 rotates at a high speed, for example, of 50,000 rpm. The rotor 11 is an inner rotor. As shown in FIG. 3 , the rotor 11 is disposed inside the stator 12. Specifically, the rotor 11 is surrounded by the stator 12 with a small air gap between them.

[0023] The rotating shaft 11a is a shaft that serves as the center of rotation of the rotor 11. The rotating shaft 11a extends in the longitudinal direction, which is the direction in which the axis C extends. The rotating shaft 11a is a metal rod made of a metal material such as SUS (Steel Use Stainless Steel). The rotating shaft 11a is rotatably attached to the center of the rotor 11.

[0024] As an example, the rotor 11 is an armature. The rotor 11 is an armature assembly having a rotor core 11b and a winding coil 11c wound around the rotor core 11b via an insulator. The winding coil 11c is shown schematically in FIG. 3 . The rotor core 11b is a magnetic body made of a magnetic material. As an example, the rotor core 11b is a laminated body in which multiple electromagnetic steel plates are stacked in the direction (axial direction) in which the axis C of the rotating shaft 11a extends. The rotor core 11b has multiple teeth protruding in the radial direction. When a current flows through the winding coil 11c, each tooth generates a magnetic force that acts on the stator 12. The rotor core 11b is surrounded by the stator 12 with a small air gap between them.

[0025] A rotating shaft 11a is fixed to the rotor core 11b. The rotating shaft 11a is fixed to the rotor core 11b while passing through the center of the rotor core 11b. For example, the rotating shaft 11a is fixed to the rotor core 11b by press-fitting or shrink-fitting into the center hole of the rotor core 11b.

[0026] The stator 12 faces the rotor 11. The stator 12 generates a magnetic force acting on the rotor 11. Specifically, the stator 12 is disposed so as to surround the rotor core 11b of the rotor 11. The stator 12 is configured so that north and south poles alternate in the circumferential direction on the air gap surface. In this case, the stator 12 may be configured so that multiple permanent magnets are disposed in the circumferential direction, or may be configured by a stator core having multiple teeth that generate main magnetic flux and a winding coil wound around the stator core. In this embodiment, the stator 12 is a field assembly in which a winding coil is wound around a stator core formed by laminating multiple electromagnetic steel plates. The stator 12 is fixed to, for example, the motor case 50.

[0027] The first bearing 13 and the second bearing 14 support the rotating shaft 11a. The first bearing 13 supports one end of the rotating shaft 11a (the end on the rotary fan 20 side). The second bearing 14 supports the other end of the rotating shaft 11a (the end opposite the rotary fan 20 side). The first bearing 13 and the second bearing 14 are bearings that support the rotating shaft 11a. As an example, the first bearing 13 and the second bearing 14 are ball bearings. However, the first bearing 13 and the second bearing 14 are not limited to ball bearings and may be other bearings such as plain bearings. In this way, both ends of the rotating shaft 11a are held by the first bearing 13 and the second bearing 14 so as to be rotatable. The first bearing 13 is fixed to the air guide unit 30. The second bearing 14 is fixed to the bottom of the motor case 50.

[0028] One end of the rotary shaft 11a protrudes from the first bearing 13. A rotary fan 20 is attached to the tip of the rotary shaft 11a protruding from the first bearing 13. The part of the rotary shaft 11a to which the rotary fan 20 is attached (the part on the first bearing 13 side) is called the output shaft. The part on the opposite side to the rotary fan 20 side (the part on the second bearing 14 side) is called the anti-output shaft.

[0029] The commutator 15 is attached to the rotating shaft 11a. Therefore, the commutator 15 rotates together with the rotating shaft 11a. In this embodiment, the commutator 15 is located on the rotating fan 20 side (output shaft side) of the rotor core 11b. Specifically, the commutator 15 is attached to a portion of the rotating shaft 11a between the rotor core 11b and the first bearing 13.

[0030] The commutator 15 has a plurality of commutator segments arranged in an annular shape surrounding the rotating shaft 11 a. The commutator segments are insulated and separated from one another in the rotational direction of the rotating shaft 11 a. Each of the commutator segments is electrically connected to the winding coil 11 c.

[0031] Brushes 16 are in contact with the commutator 15. The brushes 16 are power supply brushes for supplying power to the winding coils 11c of the rotor 11. When the brushes 16 are in contact with the commutator 15, an armature current supplied to the brushes 16 flows through the commutator 15 to the winding coils 11c. The brushes 16 are made of a conductive material. For example, the brushes 16 are conductive carbon brushes made of carbon. The brushes 16 are substantially rectangular parallelepipeds with an elongated shape.

[0032] The brushes 16 are arranged so as to be able to slide against the commutator 15. In this embodiment, a pair of brushes 16 are provided. The pair of brushes 16 are arranged opposite each other so as to sandwich the commutator 15. The brushes 16 receive a pressing force from a brass spring such as a torsion spring. The front end surfaces of the brushes 16 are in sliding contact with the commutator segments of the commutator 15. The front end surfaces of the brushes 16 wear due to contact with the commutator segments of the commutator 15. As the brushes 16 wear, the rear end surfaces of the brushes 16 move radially from the outer periphery of the rotating shaft 11a toward the axis C. The brushes 16 are housed in, for example, a brush holder.

[0033] The rotary fan 20 is an example of a fan. The rotary fan 20 draws air by rotating. Specifically, the rotary fan 20 draws air into an outer shell (housing) formed by a fan case 40 and a motor case 50. The rotary fan 20 is a centrifugal fan that can generate high suction pressure.

[0034] The rotary fan 20 is attached to a predetermined portion of the rotary shaft 11a of the electric motor 10. The rotary fan 20 rotates when the rotary shaft 11a rotates. In this embodiment, the rotary fan 20 is attached to the tip of one side of the rotary shaft 11a. The rotary fan 20 is inserted onto the rotary shaft 11a together with a fastening nut 61 and a plurality of mounting plates 62, for example. The rotary fan 20 is held under pressure on the rotary shaft 11a by tightening the fastening nut 61. The method of fixing the rotary fan 20 to the rotary shaft 11a is not limited to this.

[0035] When the electric motor 10 is driven, the rotary fan 20 rotates, generating wind pressure, and air is drawn in through the intake port 40a of the fan case 40, passes through the interior of the rotary fan 20, and is then discharged from the rotary fan 20. The air discharged from the rotary fan 20 flows into the air guide portion 30.

[0036] The rotary fan 20 has an inlet 20a (air intake) for drawing in air and an outlet 20b (exhaust port) for blowing out the air drawn in through the inlet 20a. The detailed configuration of the rotary fan 20 will be described later.

[0037] The air guide section 30 is positioned opposite the rotary fan 20. The air guide section 30 functions to form an airflow path. For example, the air guide section 30 functions to straighten the flow of air blown out from the rotary fan 20 and smoothly guide it into the motor case 50. Specifically, the air guide section 30 guides the air compressed by the rotary fan 20 into the motor case 50 while gradually returning the air to atmospheric pressure. As shown in FIG. 3 , the air guide section 30 is disposed with a gap between it and the side wall 42 of the fan case 40. The air that flows into the air guide section 30 passes through a ventilation passage formed by multiple diffuser vanes 31b and then flows into the motor case 50 through the gap between the air guide section 30 and the side wall 42 of the fan case 40. The air guide section 30 is disposed between the rotary fan 20 and the rotor 11 in the direction of the axis C of the rotary shaft 11a.

[0038] As shown in Figures 2 and 3, in this embodiment, the air guide portion 30 is separated into multiple pieces. Specifically, the air guide portion 30 is separated into an air guide 31 and a first bracket 32 ​​in the direction of the axis C of the rotating shaft 11a. The separated air guide 31 and first bracket 32 ​​are connected and held together. Specifically, the first bracket 32 ​​is fixed to the motor case 50 with screws. The fan case 40 presses the air guide 31 against the first bracket 32 ​​from above, thereby connecting and fixing the air guide 31 and the first bracket 32. Both the air guide 31 and the first bracket 32 ​​are made of a resin material. However, the air guide 31 and the first bracket 32 ​​are not limited to this, and may be made of a metal material.

[0039] The air guide 31 has a first partition plate 31a and a plurality of diffuser vanes 31b provided on the first partition plate 31a. The first partition plate 31a is a substantially annular, plate-shaped base portion. The plurality of diffuser vanes 31b are provided on the upper surface of the first partition plate 31a. The plurality of diffuser vanes 31b are provided so as to surround the sides of the rotary fan 20. Each of the plurality of diffuser vanes 31b has a plate shape that is curved in an arc. The plurality of diffuser vanes 31b are provided upright on the upper surface of the first partition plate 31a. The plurality of diffuser vanes 31b are arranged in a spiral shape around the axis C of the rotary shaft 11a.

[0040] A plurality of diffuser air passages are formed by the plurality of diffuser vanes 31b in the air guide 31. Each of the plurality of diffuser air passages is an air flow path surrounded by two adjacent diffuser vanes 31b, the first partition plate 31a, and the lid 41 of the fan case 40.

[0041] The first bracket 32 ​​has a second partition plate 32a and a plurality of guide vanes 32b (guide vanes) provided on the second partition plate 32a. The second partition plate 32a is a disk-shaped base portion. The second partition plate 32a faces the first partition plate 31a. The plurality of guide vanes 32b are provided on the lower surface of the second partition plate 32a. The plurality of guide vanes 32b are return vanes that return the air that is directed radially outward by the air guide 31 and passes by the side of the second partition plate 32a into the first bracket 32, toward the radially inward direction. Each of the plurality of guide vanes 32b has a curved plate shape. The plurality of guide vanes 32b are erected on the lower surface of the second partition plate 32a. The plurality of guide vanes 32b are arranged radially around the axis C of the rotating shaft 11a. Specifically, the guide vanes 32b are arranged in a spiral shape around the axis C of the rotary shaft 11a.

[0042] In the first bracket 32, a plurality of return ventilation passages are formed by the plurality of guide vanes 32b. Each of the plurality of return ventilation passages is an air flow path surrounded by two adjacent guide vanes 32b and the second partition plate 32a. That is, each return ventilation passage is a spatial region in which the inner surfaces of the two guide vanes 32b form a pair of side surfaces and the lower surface of the second partition plate 32a forms an upper surface. The return ventilation passage has the function of returning air that has turned back and flowed from the diffuser ventilation passage formed by the diffuser vanes 31b above the air guide section 30 to the lower side of the air guide section 30 to the center of the air guide section 30, thereby allowing air to flow from the entire lower side of the air guide section 30 downward to the lower side of the air guide section 30.

[0043] The air guide unit 30 configured in this manner also functions as a bracket that holds the first bearing 13. Specifically, the first bracket 32 ​​of the air guide unit 30 has a bearing holding portion that holds the first bearing 13. The air guide unit 30 also functions as a brush holder that holds the brush 16. Therefore, the air guide unit 30 has a brush storage portion that holds the brush 16.

[0044] The fan case 40 is a cover that covers the rotary fan 20 and the air guide portion 30. The fan case 40 is a housing that houses the rotary fan 20. As an example, the fan case 40 is a metal cover made of a metal material. However, the fan case 40 may also be a resin cover made of a resin material.

[0045] The fan case 40 has a lid portion 41 (first fan case portion) that covers the upper portion of the rotary fan 20 and the air guide portion 30, and a side wall portion 42 (second fan case portion) that covers the side portion of the rotary fan 20 and the air guide portion 30.

[0046] Fan case 40 is fixed to motor case 50. Specifically, fan case 40 and motor case 50 are fixed together by connecting side wall portion 42 of fan case 40 to the open end of the cylindrical portion of motor case 50. A fan case spacer having an opening corresponding to suction port 40a may be attached to suction port 40a of fan case 40.

[0047] The fan case 40 has an intake port 40a (air inlet) for drawing in outside air. The intake port 40a is a circular through-hole provided in the center of the lid portion 41. The intake port 40a of the fan case 40 faces the intake port 20a of the rotary fan 20. When the rotary fan 20 rotates, air flows into the fan case 40 through the intake port 40a of the fan case 40.

[0048] The motor case 50 is a second bracket. The motor case 50 houses the electric motor 10. Specifically, the motor case 50 houses the components that make up the electric motor 10, such as the rotor 11 and the stator 12. The motor case 50 is an outer casing (outer shell) of the electric blower 1 and the electric motor 10. The motor case 50 is, for example, a metal case made of a metal material.

[0049] The motor case 50 is a cylindrical housing (frame) with a bottom and an opening 50a. The motor case 50 has a bottom and cylindrical sidewalls. The bottom and sidewalls of the motor case 50 are provided with a plurality of exhaust ports 50b for exhausting air drawn in by the rotation of the rotary fan 20. In other words, the exhaust ports 50b are outlets for blowing out the air drawn into the motor case 50 by the rotary fan 20. The second bearing 14 is fixed to the bottom of the motor case 50. In other words, the motor case 50 also functions as a bracket for holding the second bearing 14.

[0050] In the electric blower 1 configured as described above, when the rotor 11 of the electric motor 10 rotates, the rotary fan 20 rotates, and air is drawn into the interior of the fan case 40 through the suction port 40a of the fan case 40. The air drawn in through the suction port 40a of the fan case 40 flows into the interior of the rotary fan 20 through the suction port 20a of the rotary fan 20 and is exhausted radially from the outlets 20b located on the outer periphery of the rotary fan 20. At this time, the air drawn into the rotary fan 20 is compressed to a high pressure by the rotary fan 20. The air exhausted from the rotary fan 20 flows into the air guide section 30 surrounding the rotary fan 20 and is guided by the diffuser vanes 31b of the air guide section 30 to the side wall section 42 of the fan case 40, where it becomes a swirling flow and flows into the motor case 50. The air that flows into the motor case 50 cools the rotor 11 and the stator 12 of the electric motor 10 and is then discharged to the outside of the electric blower 1 through the exhaust port 50 b of the motor case 50 .

[0051] Next, the detailed configuration of rotary fan 20 used in electric blower 1 according to this embodiment will be described in detail using Figures 5 and 6, with reference to Figures 2 to 4. Figure 5 is an exploded perspective view of rotary fan 20 in electric blower 1 according to this embodiment. Figure 6 is a plan view of rotary fan 20 with first fan plate 21 removed.

[0052] 2 to 6, the rotary fan 20 is a fan assembly including a pair of fan plates, a first fan plate 21 and a second fan plate 22, and a plurality of fan blades 23.

[0053] The first fan plate 21, the second fan plate 22, and the fan blades 23 are made of plate material with a uniform thickness. The first fan plate 21, the second fan plate 22, and the fan blades 23 are all made of metal plates such as aluminum plates.

[0054] As described above, the rotary fan 20 has an inlet 20a for drawing in air. The inlet 20a is provided in one of the first fan plate 21 and the second fan plate 22. In this embodiment, the inlet 20a is provided in the first fan plate 21. Therefore, the first fan plate 21 is an upper plate located on the upstream side (toward the fan case 40). The second fan plate 22 is a lower plate located on the downstream side (toward the motor case 50). As shown in FIG. 3, the inlet 20a provided in the first fan plate 21 faces the inlet 40a of the fan case 40. As shown in FIG. 4, the inlet 20a is, for example, a circular through-hole.

[0055] 2 and 3, first fan plate 21 has a flat, substantially truncated conical shape. As shown in Fig. 2, suction port 20a is provided at the top of first fan plate 21. First fan plate 21 having such a shape can be formed by drawing a circular flat plate having a through hole corresponding to suction port 20a into a flat, substantially truncated conical shape.

[0056] As shown in Fig. 3, the second fan plate 22 faces the first fan plate 21. Specifically, the second fan plate 22 faces the first fan plate 21 across a predetermined gap. The second fan plate 22 is a flat, circular plate. A through-hole is provided in the center of the second fan plate 22. The rotary shaft 11a is inserted into this through-hole.

[0057] The fan blades 23 are disposed between the first fan plate 21 and the second fan plate 22. The fan blades 23 are sandwiched between the first fan plate 21 and the second fan plate 22. Each of the fan blades 23 is an arc-shaped plate and is arranged radially. As shown in Figures 5 and 6, the fan blades 23 are arranged radially in a vortex pattern. The rotary fan 20 has, for example, 11 fan blades 23.

[0058] The space surrounded by two adjacent fan blades 23 and the first and second fan plates 21, 22 is an air passage through which air that flows into rotary fan 20 from inlet 20a passes. The opening on the radially outer side of this air passage is outlet 20b. In this embodiment, multiple air passages are formed in a spiral shape along a plane perpendicular to axis C of rotary shaft 11a. In other words, outlet 20b opens in a direction along axis C of rotary shaft 11a. Multiple outlets 20b are formed around the circumferential direction of rotary fan 20.

[0059] The first fan plate 21, the second fan plate 22, and the fan blades 23 are fixed to one another by crimping. Specifically, as shown in Fig. 5 , the multiple first protrusions 23a on the upper end surface of the fan blade 23 are inserted into the multiple through-holes 21a of the first fan plate 21, and the multiple second protrusions 23b on the lower end surface of the fan blade 23 are inserted into the multiple through-holes 22a of the second fan plate 22, and the multiple first protrusions 23a and the multiple second protrusions 23b on the fan blade 23 are crimped together, thereby connecting and fixing the first fan plate 21, the second fan plate 22, and the fan blades 23 to one another.

[0060] In the rotary fan 20 configured as described above, the fan blades 23 are not arranged at equal circumferential pitch. In other words, the fan blades 23 are not arranged at constant intervals. However, although the fan blades 23 are not arranged at equal pitch, they are arranged with a regularity. Specifically, the inter-blade angles of the fan blades 23 are arranged at regular intervals according to a sinusoidal function. More specifically, for the fan blades 23, if the pitch is θp, the maximum deviation angle is m, the order is n (n is an integer greater than or equal to 1), and the blade number is a (i.e., the a-th fan blade 23), then the inter-blade angle θ of the fan blade 23 with blade number a satisfies the following (Equation 1):

[0061]

[0062] In this case, the total number of fan blades 23 is a+1. The order n indicates the wavelength (period) of the sine wave function of (Equation 1) for the total number of fan blades 23, from 0th to (a+1). For example, order n=1 means that fan blades 23 from 0th to (a+1)th are assigned to a sine wave of one wavelength (one period). Similarly, order n=2 means that fan blades 23 from 0th to (a+1)th are assigned to a sine wave of two wavelengths (two periods). As shown in FIG. 6 , the inter-blade angle θ of the fan blades 23 is the angle between two line segments connecting the center of the rotary fan 20 and the outer ends of two adjacent fan blades 23.

[0063] FIG. 7 is a plan view of the rotary fan 20 (when n = 2) with the first fan plate 21 removed. Both FIGS. 6 and 7 show a rotary fan 20 with 11 fan blades 23. FIG. 6 shows the layout of 11 fan blades 23 when n = 1. FIG. 7 shows the layout of 11 fan blades 23 when n = 2. In Equation 1, m and θp are constants. In FIGS. 6 and 7, m = 3 and pitch θp = 32.727 (°). The position of the fan blade 23 with a = 0 (the 0th fan blade 23) among the multiple fan blades 23 is arbitrary.

[0064] Figures 8 and 9 show the relationship between the blade number a and the inter-blade angle θ of the fan blades 23 when n = 1 (the case of Figure 6) and when n = 2 (the case of Figure 7) for 11 fan blades 23 arranged according to Equation 1. Figure 8 is a graph showing the relationship between the blade number and the inter-blade angle of the fan blades 23 (total number = 11) in the rotary fan 20 of the electric blower 1 according to the embodiment. Figure 9 is a table showing specific values ​​showing the relationship between the blade number and the inter-blade angle of the fan blades 23 (total number = 11) in the rotary fan 20 of the electric blower 1 according to the embodiment.

[0065] In this embodiment, the number of fan blades 23 is 11. However, this is not limiting. For example, the number of fan blades 23 may be 16. FIGS. 10 and 11 show the relationship between the blade number a of the fan blades 23 and the inter-blade angle θ when n = 1 and when n = 2 for 16 fan blades 23 arranged according to Equation 1. FIG. 10 is a graph showing the relationship between the blade number and the inter-blade angle of the fan blades 23 (total number = 16) in the rotary fan 20 of the electric blower 1 according to this embodiment. FIG. 11 is a table showing specific values ​​indicating the relationship between the blade number and the inter-blade angle of the fan blades 23 (total number = 16) in the rotary fan 20 of the electric blower 1 according to this embodiment.

[0066] As described above, electric blower 1 according to this embodiment includes electric motor 10 equipped with rotor 11 having rotary shaft 11a, and rotary fan 20 attached to rotary shaft 11a. Multiple fan blades 23 in rotary fan 20 are not arranged at regular intervals. However, multiple fan blades 23 are arranged at an inter-blade angle θ that satisfies the above-mentioned (Equation 1).

[0067] This configuration can reduce noise peaks at specific frequencies (for example, multiples of the number of fan blades), thereby suppressing noise generated by the entire electric blower 1.

[0068] In this case, the number of the fan blades 23 may be an even number, but is preferably an odd number. By using an odd number of the fan blades 23, noise can be reduced compared to when the number is an even number. The order n may be an odd number, but is preferably an even number. For example, the order n may be n=1, but is preferably n=2. If the order n is an odd number, the balance of the fan blades 23 will be poor. However, by using an even number for the order n, the imbalance of the fan blades 23 can be improved.

[0069] Therefore, it is preferable that the number of the fan blades 23 is an odd number and the order n is an even number. For example, it is preferable that the number of the fan blades 23 is 11 and the order n is 2 (i.e., two periods of a sine wave).

[0070] This configuration can improve the imbalance among the multiple fan blades 23 and further reduce noise peaks at specific frequencies.

[0071] The number of the fan blades 23 is preferably 7 or more and 15 or less.

[0072] This configuration makes it possible to reduce noise peaks at specific frequencies while maintaining high wind pressure from the rotary fan 20.

[0073] Furthermore, in the electric blower 1 according to this embodiment, the diffuser vanes 31b of the air guide section 30 are arranged at equal intervals in the circumferential direction. However, this is not limiting. That is, the diffuser vanes 31b of the air guide section 30 do not have to be arranged at regular intervals. In this case, the diffuser vanes 31b may be arranged with a regularity. Specifically, the inter-blade angles of the diffuser vanes 31b may be arranged at regular intervals according to a sinusoidal function, similar to the fan vanes 23. More specifically, for the diffuser vanes 31b, if the pitch is αp, the maximum deviation angle is j, the order is k (k is an integer greater than or equal to 1), and the blade number is b (i.e., the b-th fan vane 23), the inter-blade angle α of the fan vane 23 with blade number b satisfies the following (Equation 2):

[0074]

[0075] This configuration can further reduce noise peaks at specific frequencies, thereby further suppressing noise generated by the entire electric blower 1.

[0076] In this case, the number of the diffuser vanes 31b may be an odd number, similar to the fan vanes 23. In the diffuser vanes 31b, the order k may be an odd number, but is preferably an even number, similar to the fan vanes 23. For example, the order k may be 1, but is preferably 2.

[0077] In other words, it is preferable that the number of the diffuser vanes 31b is an odd number and the order k is an even number.

[0078] This configuration can improve the imbalance among the plurality of diffuser vanes 31b and can further reduce noise peaks at specific frequencies.

[0079] The above formula (2) may also be applied to the plurality of guide vanes 32b in the air guide portion 30.

[0080] (Modification) The electric blower according to the present disclosure has been described above based on the embodiment, but the present disclosure is not limited to the above embodiment.

[0081] For example, in the above embodiment, both the multiple fan blades 23 in the rotary fan 20 and the multiple diffuser blades 31b in the air guide section 30 are not arranged at equal pitches. However, this is not limited to this. Specifically, it is sufficient that at least one of the multiple fan blades 23 and the multiple diffuser blades 31b is not arranged at equal pitches, and the other of the multiple fan blades 23 and the multiple diffuser vanes 31b may be arranged at equal pitches. In other words, only the multiple fan blades 23 may be arranged so as to satisfy (Equation 1), or only the multiple diffuser vanes 31b may be arranged so as to satisfy (Equation 2).

[0082] In the above embodiment, the air guide unit 30 is configured by two components, the air guide 31 and the first bracket 32. However, this is not limiting. For example, the air guide unit 30 may be a single component in which the air guide 31 and the first bracket 32 ​​are integrated.

[0083] In the above embodiment, the electric motor 10 used in the electric blower 1 is a brushed commutator motor, but this is not limitative. The electric motor 10 may be a brushless motor or the like.

[0084] In the above embodiment, the electric blower 1 is described as being used in an electric vacuum cleaner. However, the present invention is not limited to this. For example, the electric blower 1 may be used in an air towel or the like.

[0085] In addition, the present disclosure also includes forms obtained by applying various modifications to the above-described embodiments that a person skilled in the art would conceive, or forms realized by arbitrarily combining the components and functions of the embodiments within the scope of the present disclosure. The present disclosure also includes any combination of two or more claims from the multiple claims set forth in the claims at the time of filing, provided that there is no technical contradiction. For example, when a dependent claim set forth in the claims at the time of filing is made into a multiple claim or multiple multiple claims that cite all of the superordinate claims within the scope of the technical contradiction, the present disclosure also includes all combinations of claims included in that multiple claim or multiple multiple claims.

[0086] The technology of the present disclosure can be used in various electrical appliances that use electric blowers, and is particularly useful as electric blowers installed in electric vacuum cleaners and the like that rotate fans at high speeds.

[0087] DESCRIPTION OF SYMBOLS 1 Electric blower 10 Electric motor 11 Rotor 11a Rotating shaft 11b Rotor core 11c Winding coil 12 Stator 13 First bearing 14 Second bearing 15 Commutator 16 Brush 20 Rotary fan 20a Intake port 20b Outlet 21 First fan plate 21a Through hole 22 Second fan plate 22a Through hole 23 Fan blade 23a First protrusion 23b Second protrusion 30 Air guide portion 31 Air guide 31a First partition plate 31b Diffuser blade 32 First bracket 32a Second partition plate 32b Guide blade 40 Fan case 40a Intake port 41 Lid portion 42 Side wall portion 50 Motor case (second bracket) 50a Opening 50b Exhaust port 61 Fastening nut 62 Mounting plate

Claims

1. An electric motor including a rotor having a rotating shaft; and a rotary fan attached to the rotating shaft, wherein the rotary fan has a plurality of fan blades, and wherein, for the plurality of fan blades, the pitch is θp, the maximum deviation angle is m, the order is n (n is an integer of 1 or more), and the blade number is a, the inter-blade angle θ of the fan blade with blade number a satisfies the following (Equation 1): Electric blower.

2. The electric blower according to claim 1, wherein the number of the plurality of fan blades is an odd number, and the order is an even number.

3. The electric blower according to claim 1, wherein the number of the plurality of fan blades is 7 or more and 15 or less.

4. An electric blower according to any one of claims 1 to 3, wherein the rotary fan has a first fan plate having an intake port and a second fan plate facing the first fan plate, and the fan blades are arranged between the first fan plate and the second fan plate.

5. The fan further comprises an air guide section located opposite the rotary fan and into which air discharged from the rotary fan flows, the air guide section having a plurality of diffuser vanes, wherein, in the plurality of diffuser vanes, when the pitch is αp, the maximum deviation angle is j, the order is k (k is an integer of 1 or more), and the vane number is b, the inter-blade angle α of the guide vane having the vane number b satisfies the following (Equation 2): The electric blower according to any one of claims 1 to 3.

6. An electric motor including a rotor having a rotating shaft; a rotary fan attached to the rotating shaft; and an air guide section positioned opposite the rotary fan and into which air discharged from the rotary fan flows, wherein the air guide section has a plurality of diffuser vanes, and wherein, in the plurality of diffuser vanes, when the pitch is αp, the maximum deviation angle is j, the order is k (k is an integer of 1 or more), and the vane number is b, the inter-blade angle α of the guide vane having the vane number b satisfies the following (Equation 2): Electric blower.

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