JP2014030298A - Motor-driven blower - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor-driven blower capable of suppressing a decrease in motor efficiency by improving cooling performance for field winding although making the motor compact.SOLUTION: A motor-driven blower includes: a blower part 2 and a rectifier motor 3. The rectifier motor 3 includes: a stator 7 and a rotor 8, the stator 7 includes: a stator core 9 and a field winding 10, and the rotor 8 includes: a shaft 11, a rotor 12, and a rectifier 13. The stator core 9 includes: long-side parts 9a, 9b which are sectioned in a rectangular and annular shape, extended along long sides of the rectangle, and provided with magnetic poles 22a, 22b inside, and is fixed while inscribed with a frame 6. Denoting the length of a short side of an outer shape of the stator core 9 as B, B is so set as to satisfy d+2g<B≤d+2g+2W, where W is widths of the long-side parts 9a, 9b, "d" is an external diameter of a rotor core 12, and "g" is a dimension of a gap 20 between the stator 7 and rotor 8.

Description

  The present invention relates to an electric blower.

  An electric blower unit, which is mounted on a vacuum cleaner or the like and in which a blower unit and a motor are integrated, is generally used at a high rotational speed of 30000 to 45000 r / min. Therefore, a commutator motor having two magnetic poles is used. Yes. In this electric blower, since the amount of heat generated by the motor is large, a structure is adopted in which the exhaust from the blower section is guided into the frame of the motor to cool the motor.

  By the way, household vacuum cleaners are strongly required to be lighter, but there are several problems in reducing the parts of the motor uniformly from the conventional shape to a similar shape in order to reduce the weight. is there.

  One is that it is difficult to make the outer diameter of the rotor core significantly smaller than the conventional one when the required output and the service life (life) are determined. In the winding process of the armature winding in the manufacturing process, it is necessary to cross the windings between slots spaced by a predetermined pitch while avoiding interference with the commutator directly above the rotor core. When the outer diameter of the rotor core is reduced, it is necessary to reduce the outer diameter of the commutator in order to avoid interference during the winding operation. However, when the outer diameter of the commutator is reduced, the contact area between the brush and the commutator segment is reduced accordingly, so that the current density is increased and the necessary brush life cannot be obtained. Moreover, since the space | interval of segments becomes short, ensuring of insulation becomes difficult. Therefore, in order to reduce the weight of the motor, it is an issue to reduce the size of the stator core without reducing the outer diameter of the rotor core.

  There is also a problem of temperature rise of the field winding. When the outer shape of the stator core is reduced, the space on both sides of the magnetic pole is reduced, so that the wire diameter of the field winding must be reduced. When the wire diameter of the field winding is reduced, the electrical resistance is increased and the amount of heat generation is increased, and when the winding temperature is increased, the electrical resistance is further increased. As the electric resistance of the field winding increases, the copper loss increases, leading to a reduction in motor efficiency. Therefore, improving the cooling performance of the field winding is also a problem in reducing the weight of the motor.

  Patent Document 1 shows a structure in which a stator core having a substantially square outer shape is inscribed and fixed to a cylindrical frame. Further, there is a description that the cooling efficiency can be increased by making the cross-sectional areas of the four air passages partitioned by the frame and the outer shape of the stator core substantially equal.

Japanese Examined Patent Publication No. 62-038939

  However, the prior art of Patent Document 1 does not disclose specific means for reducing the weight. Even if the outer shape of the stator core is reduced to a substantially square-like shape, there is a problem that the temperature of the field winding increases. Usually, the field windings generate more heat than the stator cores, and this is particularly noticeable when the field windings are thinned in order to reduce the outer shape of the stator core for the purpose of reducing the weight. Therefore, it is better to devise the ratio of the cross-sectional area of the four air paths so that the air volume touching the field winding increases than to make the cross-sectional areas of the four air paths equal as the outer shape of the stator core is reduced. Get better.

  The present invention has been made in view of the above, and an object of the present invention is to provide an electric blower that can improve the cooling performance of the field winding and suppress the reduction in motor efficiency while reducing the weight of the motor.

  In order to solve the above-described problems and achieve the object, an electric blower according to the present invention has a cylindrical frame, a cross-sectional shape perpendicular to the axial direction of the frame is annular, and an outer shape is substantially rectangular. A pair of short sides extending in the short side direction of the rectangle and a pair of long sides disposed between the pair of short sides and extending in the long side direction of the rectangle and provided with a pair of magnetic poles inside And a stator core that is inscribed and fixed to the frame, and is wound around the pair of magnetic poles, and a coil end is disposed so as to bypass the outside of the pair of long sides. A winding, an annular rotor core that is rotatably arranged facing the inside of the stator core via a gap and fixed to the shaft; an armature winding wound around the rotor core; and the shaft fixed to the shaft Connected to the armature winding A rotor having a commutator, a fan that rotates as the rotor rotates, a fan guide that guides an air flow accompanying the rotation of the fan to an air path provided between the frame and the stator core, In each of the long side portions, the first width on both sides of the magnetic pole provided on the long side portion is larger than the second width at the central portion of the magnetic pole, and the short side of the outer shape of the stator core When B is the length, W is the first width of the pair of long sides, d is the outer diameter of the rotor core, and g is the gap distance, B is such that d + 2g <B <d + 2g + 2W. It is characterized by being set.

  According to the present invention, it is possible to improve the cooling performance of the field windings while reducing the weight of the motor and to suppress the reduction in motor efficiency.

1 is a longitudinal sectional view showing a schematic structure of an electric blower according to Embodiment 1. FIG. FIG. 2 is a view of the main part of the commutator motor according to the first embodiment when viewed from the axial direction on the fan side. FIG. 3 shows the relationship between (B / D) and S. FIG. 4 is a view of the main part of the commutator motor according to the second embodiment viewed from the axial direction on the fan side. FIG. 5 is a cross-sectional view at the position of the brush of the commutator motor of the electric blower according to the third embodiment. FIG. 6 is a view of the main part of the commutator motor according to Embodiment 4 as viewed from the axial direction on the fan side, and is a view showing the easy magnetization direction with arrows. FIG. 7 is a configuration diagram corresponding to FIG. 2 when A <B. FIG. 8 is a cross-sectional view at the position of the brush of the commutator motor of the electric blower according to the third embodiment.

  Embodiments of an electric blower according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

Embodiment 1 FIG.
FIG. 1 is a longitudinal sectional view showing a schematic structure of the electric blower according to the present embodiment. The electric blower 1 is roughly divided into two units: a blower unit 2 that generates suction force and a commutator motor 3 that drives the blower unit 2. The electric blower 1 can be applied to a vacuum cleaner, for example.

  The blower unit 2 includes a fan 4 having a plurality of blades and a fan guide 5 that covers the fan 4 and guides air that flows along with the rotation of the fan 4 to the commutator motor 3. The commutator motor 3 is fixed to the inside of a cup (cylinder) -shaped frame 6 and serves as a field, and is arranged to face the inside of the stator 7 with a gap 20 therebetween, and is rotatably supported. And a rotor 8 serving as an armature.

  The stator 7 includes a stator core 9 formed by laminating and fixing a plurality of electromagnetic steel plates, and a field winding 10 wound around the stator core 9. A magnetic field is generated inside the stator 7 by passing a current through the field winding 10.

  The rotor 8 includes a shaft 11 disposed in the center, an annular rotor core 12 formed by laminating and fixing a plurality of electromagnetic steel plates fixed around the shaft 11, an armature winding 17 wound around the rotor core 12, A commutator 13 is provided separately from the rotor core 12 and fixed around the shaft 11, and is rotatably supported by the frame 6 via the shaft 11 and bearings 14 and 15.

  The bearing 14 on the side of the blower part 2 is accommodated in a bracket 21 provided so as to cross the opening of the frame 6, and the bearing 15 on the other side (opposite to the side of the blower part 2) is accommodated in the bottom of the frame 6. Is done.

  The fan 4 is fixed to the end portion 16 of the shaft 11 on the blower portion 2 side, and the fan 4 is rotationally driven as the rotor 8 rotates. The starting end (end of winding start) and the end (end of winding end) of a plurality of coils constituting the armature winding 17 are electrically connected to the segment 18 of the commutator 13 by a method such as fusing (heat caulking). Is done. A pair of brushes 19 held in the frame 6 and pressed against the commutator 13 by a spring to come into sliding contact are connected to one of the field windings 10 and the other is connected to the other of the field windings 10. The field winding is connected to a power source (not shown) and supplies a current (armature current) to the armature winding 17 via the commutator 13.

  Rotational torque is generated in the rotor 8 by the magnetic field generated by the stator 7 and the armature current. In order to make the rotation direction of the rotor 8 constant, the armature winding 17 and the segment 18 are connected so that the coil through which the armature current flows is switched in accordance with the phase of the rotor 8.

  FIG. 2 is a view of the main part of the commutator motor 3 viewed from the axial direction on the fan 4 side. However, in FIG. 2, the frame 6 is a cross section. As shown in FIG. 2, the stator core 9 has an annular shape and a substantially rectangular outer shape, and is inscribed and fixed to the cylindrical frame 6. The inner diameter of the frame 6 is represented by D, the long side of the substantially rectangular shape that is the outer shape of the stator core 9 is represented by A, and the short side is represented by B. The stator core 9 includes a short side portion 9c including one short side of the rectangle and extending in the short side direction with a substantially constant width, and extends in the short side direction including the other short side of the rectangle with a substantially constant width. The short side portion 9d is disposed between the short side portions 9c and 9d, is provided integrally with the short side portions 9c and 9d, extends in the long side direction of the rectangle, and has a magnetic pole 22a on the inner side (inner diameter side). Arranged between the long side portion 9a and the short side portions 9c, 9d, provided integrally with the short side portions 9c, 9d, extended in the long side direction of the rectangle and provided with a magnetic pole 22b on the inner side (inner diameter side). And a long side portion 9b.

  The short sides 9c and 9d have, for example, the same width and face each other in the long side direction. The long side portion 9a has a substantially constant width W except for a portion where the magnetic pole 22a is provided. That is, the width W of the long side portion 9a on both sides in the long side direction of the magnetic pole 22a is substantially constant. Similarly, the long side portion 9b has a substantially constant width W except for a portion where the magnetic pole 22b is provided. That is, the long side portion 9b has a substantially constant width W on both sides in the long side direction of the magnetic pole 22b. The long side portions 9a and 9b face each other in the short side direction. In the illustrated example, the width of the short sides 9c and 9d is also W, for example. In this manner, the stator core 9 has a substantially rectangular annular shape as shown in FIG. 2 in the cross section perpendicular to the axial direction of the frame 6 or the shaft 11, and a pair of magnetic poles 22a and 22b are provided on the long sides 9a and 9b. Is provided.

  Inside the stator core 9, a rotor core 12 having a circular section with a shaft 11 provided at the center is rotatably disposed. The rotor core 12 is provided with a plurality of tooth portions 12a along the outer periphery, and a slot portion 12b is provided between adjacent tooth portions 12a. The outer diameter of the rotor core 12 is represented by d. In FIG. 2, only a part of the tooth portion 12a and the slot portion 12b is shown. The above-described armature winding 17 is wound around the tooth portion 12a of the rotor core 12 via the slot portion 12b, but the illustration of the armature winding 17 is also omitted.

  The magnetic poles 22a and 22b both project inward (inner diameter side) and face each other. Thus, the number of magnetic poles is 2. The shape of the inner side (inner diameter side) of the magnetic poles 22 a and 22 b is an arc shape along the outer shape of the rotor core 12. The air gap 20 is determined by the distance between the magnetic poles 22 a and 22 b and the rotor core 12. The space | interval of the space | gap 20 is represented by g. The width ε (second width) at the center in the long side direction of the magnetic poles 22a and 22b is shorter than the width W (first width).

  The field winding 10 is wound around the two magnetic poles 22 a and 22 b of the stator core 9. Specifically, the space (gap α) between one tip portion of the magnetic pole 22a (a portion projecting toward the inner diameter side) and the short side portion 9c, and the other tip portion (projecting toward the inner diameter side) of the magnetic pole 22a. Space (gap α) between the short side portion 9d and the short side portion 9c, the space (gap α) between one tip portion (protruding on the inner diameter side) of the magnetic pole 22b, and the magnetic pole The field winding 10 is wound using a space (gap α) between the other tip end portion (a portion projecting on the inner diameter side) of 22b and the short side portion 9d. Since the coil ends 10a and 10b interfere with the rotor 8 when both sides of the magnetic poles 22a and 22b are connected by a straight line of the shortest path, the coil ends 10a and 10b are detoured to the outside of the long side portions 9a and 9b in an arc shape. Is avoiding.

  An air passage 25a is provided between the outside of the long side portion 9a and the inside of the frame 6, and an air passage 25b is provided between the outside of the long side portion 9b and the inside of the frame 6, and the short side portion 9c. An air path 25 c is provided between the outside of the frame 6 and the inside of the frame 6, and an air path 25 d is provided between the outside of the short side portion 9 d and the inside of the frame 6. Air guided from the blower unit 2 through the fan guide 5 along with the rotation of the fan 4 flows through the air passages 25a to 25d. The coil ends 10a and 10b of the field winding 10 face air paths 25a and 25b outside the long sides 9a and 9b, respectively. Note that the air path is also provided in a space between the rotor core 12 and the short side portion 9c and a space between the rotor core 12 and the short side portion 9d.

In the present embodiment, the length A of the long side of the outer shape of the stator core 9, the length B of the short side, the width W of the long side portions 9a and 9b, the outer diameter d of the rotor core 12, the gap g of the air gap 20, the frame 6 For the inner diameter D of
d + 2g <B ≦ d + 2g + 2W (Formula 1)
B is set so that The reason is as follows.

The projected area S of the outer shape of the stator core 9 is
S = A × B (Formula 2)
It is. Although the projected area includes a cross section of the field winding 10 (for example, copper) and a gap (air), the weight of the commutator motor 3 is considered to decrease the value of S when viewed broadly. Good. Since the stator core 9 is inscribed in the frame 6, the following expression is substantially established.
A ² + B ² = D ² (Formula 3)

From (Expression 2) and (Expression 3),
S = (D ² −B ² ) ^0.5 × B
Therefore, the following equation holds.
S = D ² × (1− (B / D) ² ) ^0.5 × (B / D) (Formula 4)

  FIG. 3 shows the relationship between S and (B / D) with (B / D) as a variable from (Equation 4). As shown in FIG. 3, the value of S becomes maximum when the value of (B / D) is √0.5, that is, when the outer shape of the stator core 9 is square, and the value of (B / D) is 0 or 1. It gets smaller as it gets closer to. Making the value of (B / D) close to 0 corresponds to reducing B, and approaching 1 corresponds to reducing A.

  When A is reduced, the cross-sectional areas of the air passages 25a and 25b outside the long side portions 9a and 9b are reduced, and the cross-sectional areas of the air passages 25c and 25d outside the short side portions 9c and 9d are increased. Since the coil ends 10a and 10b of the field winding 10 face the air paths 25a and 25b outside the long sides 9a and 9b, respectively, when A is reduced, the cooling efficiency of the field winding 10 is descend.

  In general, the winding operation of the field winding 10 is performed by covering the magnetic poles 22a and 22b with a tool called a former, and sliding the field winding 10 on the former from the gap α to the base side of the magnetic poles 22a and 22b. This is done by inserting into When A is reduced, the gap α is narrowed, the filling factor (space factor) of the field winding 10 is lowered, and the motor efficiency is lowered. FIG. 7 shows a configuration corresponding to FIG. 2 when B> A. As shown in FIG. 7, when A is reduced, the gap α is reduced, and it becomes difficult to wind the field winding 10 using the gap α.

  When B is reduced, the cross-sectional areas of the air passages 25a and 25b outside the long side portions 9a and 9b increase, and the cross-sectional areas of the air passages 25c and 25d outside the short side portions 9c and 9d decrease. Since the coil ends 10a and 10b of the field winding 10 face the air paths 25a and 25b outside the long sides 9a and 9b, respectively, when B is reduced, the cooling efficiency of the field winding 10 is improves. Therefore, it is advantageous to make B smaller than A.

The limit for reducing B is determined by the required length of the width (thickness) ε at the center of the magnetic poles 22a and 22b. Since the magnetic flux is divided into right and left near the center of the magnetic poles 22a and 22b, the magnetic flux density is lower in the vicinity of the center than the other parts of the stator core 9. However, although the magnetic flux generated in the field winding 10 is symmetrical, there is a magnetic flux generated in the armature winding 17, so that the distribution of the synthesized magnetic flux density is not symmetrical and is behind the rotational direction. Sneak away. Because of this deviation, the magnetic flux slightly passes near the center of the magnetic poles 22a and 22b, so a width (thickness) ε (of course smaller than W at the maximum) corresponding to the magnetic flux is required. Further, a minimum width (wall thickness) ε for securing the strength of the stator core 9 is required. So ε is
0 <ε ≦ W (Formula 5)
It is appropriate to select from the range of On the other hand, B
B = d + 2g + 2ε (formula 6)
It is represented by Therefore, it is appropriate to define B by (Expression 1) obtained from (Expression 5) and (Expression 6).

  With the above configuration, while the commutator motor 3 is reduced in weight, the air path cross-sectional area on the back side of the magnetic poles 22a and 22b is increased and the air volume is increased, so that the field winding 10 in the vicinity can be cooled. This improves the motor efficiency and prevents a decrease in motor efficiency.

Embodiment 2. FIG.
FIG. 4 is a view of the main part of the commutator motor 3 in the present embodiment as viewed from the axial direction on the fan 4 side. The configuration of FIG. 1 is the same as that of the first embodiment. FIG. 4 is a view in which a bracket 21 is added to FIG. However, unlike FIG. 2, the frame 6 is not a cross section. In FIG. 4, the same components as those in FIGS. 1 and 2 are denoted by the same reference numerals.

  As shown in FIG. 4, in the present embodiment, the bracket 21 that houses the bearing 14 on the blower portion 2 side includes magnetic poles 22a and 22b in the direction crossing the opening of the frame 6 (longitudinal direction of the bracket 21). It arrange | positions so that it may become substantially parallel to long side part 9a, 9b. Such an arrangement configuration of the bracket 21 has the following advantages.

  The shaded portion in FIG. 4 shows the portion of the air path that is blocked by the bracket 21. The portions to be blocked are only the air passages 25c and 25d outside the short sides 9c and 9d, and the air passages 25a and 25b outside the long sides 9a and 9b are not blocked at all. Since the gap between the short sides 9c, 9d and the frame 6 is narrower than the gap between the long sides 9a, 9b and the frame 6, the direction in which the bracket 21 crosses the opening of the frame 6 (longitudinal direction of the bracket 21) is long. The portion where the air passage is blocked is smaller when the air passages are arranged so as to be substantially parallel to the side portions 9a, 9b than when arranged so as to be substantially orthogonal. In the configuration of FIG. 4, the bracket 21 does not block the axial direction of the field winding 10.

  With the above configuration, the cross-sectional area of the air passage blocked by the bracket 21 can be reduced. Further, since the bracket 21 does not block the axial direction of the field winding 10, it does not interfere with the cooling air that directly hits the field winding 10 from the axial direction. Other configurations, operations, and effects of the present embodiment are the same as those of the first embodiment.

Embodiment 3 FIG.
FIG. 5 is a cross-sectional view at the position of the brush 19 of the commutator motor 3 of the electric blower 1 according to the present embodiment. The schematic structure of the electric blower 1 and the configuration of the commutator motor 3 in the present embodiment are the same as those in the first embodiment (see FIGS. 1 and 2). In FIG. 5, the same components as those in FIGS. 1 and 2 are denoted by the same reference numerals. FIG. 8 is a cross-sectional view at the position of the brush 19 of the commutator motor 3 of the electric blower 1 showing another arrangement of the brush 19.

  In the present embodiment, in addition to the configuration of the first embodiment, as shown in FIG. 5, the brush 19 that contacts the commutator 13 is disposed on the air passages 25a and 25b outside the long sides 9a and 9b. ing. That is, when viewed in plan from the axial direction of the frame 6, the brush 19 is disposed so as to cross the air passages 25a, 25b substantially parallel to the short sides 9c, 9d.

  Therefore, in FIG. 8, the cooling air touching the brush 19 is small. However, in addition to the effects of the first embodiment, the long side portions 9 a and 9 b with the increased airflow cross-sectional area and the increased air volume can be obtained. By disposing the brush 19 on the outer air passages 25a and 25b, the amount of cooling air that touches the brush 19 is increased, and the cooling performance is improved. Since a rectifying spark is generated at the contact portion between the brush 19 and the commutator 13, the temperature is high. In general, the higher the temperature, the faster the wear of the brush 19 proceeds. Therefore, the life of the brush 19 can be extended by improving the cooling performance of the brush 19. Note that the present embodiment and the second embodiment can be combined.

Embodiment 4 FIG.
FIG. 6 is a view of the main part of the commutator motor 3 according to the present embodiment as viewed from the axial direction on the fan 4 side, and is a view showing the easy magnetization direction by arrows. In FIG. 6, a two-dot chain line indicates a rough center line of the magnetic path on the left half side.

  In the present embodiment, in addition to the configuration of the first embodiment, as shown in FIG. 6, the easy magnetization direction of the material of the stator core 9 is made substantially parallel to the long side portions 9a and 9b.

  The length of the magnetic path passing through the stator core 9 is approximately L1 = A−W in the direction parallel to the easy magnetization direction and L2 = B−W in the direction orthogonal to the easy magnetization direction. For A> B, L1> L2. That is, since the ratio of the total magnetic path length in the stator core 9 is the length of the magnetic path parallel to the easy magnetization direction> the length of the magnetic path orthogonal to the easy magnetization direction, the motor efficiency can be improved. Other configurations, operations, and effects of the present embodiment are the same as those of the first embodiment. Further, the present embodiment can be combined with the second and third embodiments.

  The present invention is suitable for an electric blower for a vacuum cleaner, for example.

  DESCRIPTION OF SYMBOLS 1 Electric blower, 2 Blower part, 3 Commutator motor, 4 Fan, 5 Fan guide, 6 Frame, 7 Stator, 8 Rotor, 9 Stator core, 9a, 9b Long side part, 9c, 9d Short side part, 10 Field winding Wire, 10a, 10b coil end, 11 shaft, 12 rotor core, 12a teeth, 12b slot, 13 commutator, 14, 15 bearing, 16 end, 17 armature winding, 18 segment, 19 brush, 20 air gap, 21 Bracket, 22a, 22b Magnetic pole, 25a-25d Air path.

Claims (4)

A cylindrical frame,
The cross-sectional shape perpendicular to the axial direction of the frame is annular and the outer shape is substantially rectangular, and is disposed between a pair of short sides extending in the short side direction of the rectangle and the pair of short sides. A stator core extending in the long side direction of the rectangle and having a pair of long side portions provided with a pair of magnetic poles on the inside, and inscribed and fixed to the frame;
Field windings wound around the pair of magnetic poles and arranged so that the coil ends bypass the outside of the pair of long sides,
An annular rotor core that is rotatably arranged facing the inside of the stator core via a gap and fixed to a shaft, an armature winding wound around the rotor core, and an armature winding fixed to the shaft A rotor having a commutator connected to the
A fan that rotates as the rotor rotates;
A fan guide for guiding an air flow accompanying the rotation of the fan to an air path provided between the frame and the stator core;
With
In each of the long side portions, the first width on both sides of the magnetic pole provided on the long side portion is larger than the second width in the central portion of the magnetic pole,
When the length of the short side of the outer shape of the stator core is B, the first width of the pair of long side portions is W, the outer diameter of the rotor core is d, and the gap interval is g,
d + 2g <B ≦ d + 2g + 2W
An electric blower characterized in that B is set so that The shaft is supported by a pair of bearings,
A bracket for housing the fan-side bearing is provided so as to bridge across the opening of the frame;
2. The electric blower according to claim 1, wherein the bracket is arranged so that a longitudinal direction that is a direction crossing the opening is substantially parallel to the pair of long sides. A brush is provided in sliding contact with the commutator and electrically connected to the armature winding via the commutator;
The electric blower according to claim 1, wherein the brush is disposed on an air path outside the pair of long side portions.   The electric blower according to any one of claims 1 to 3, wherein a direction of easy magnetization of the material of the stator core is substantially parallel to the pair of long side portions.