JP5452403B2 - Commutator motor, electric blower and vacuum cleaner - Google Patents

Description

  The present invention relates to a commutator motor having a brush, an electric blower including the commutator electric motor, and a vacuum cleaner including the electric blower.

  Most commutator motors are used in electric tools and home appliances such as vacuum cleaners and hair dryers. Most of these are commutator motors with an AC power supply of 100V, and lightness is more important than the efficiency of electric machines, and they are characterized by small size, light weight and high torque. In addition, there are few usage examples of home appliances that require replacement of the brush within the life of the product.

  A commutator motor used as a driving source for an electric vacuum cleaner transmits and receives electric power to an annular stator, an armature disposed between magnetic poles of the stator, and an armature winding of the armature Mainly composed of commutator and brush. This type of commutator motor for a vacuum cleaner is required to have higher output, higher efficiency, smaller size and lighter weight, longer brush life, and lower vibration. In particular, in recent years, consumers are highly aware of energy saving from the viewpoint of protecting the global environment, and the demand for higher efficiency is increasing.

  The input is increased for higher output, and a nominal input of 1 kW is standard by the “JIS C 9108 vacuum cleaner”. A high-resistance brush is used for extending the life of the brush, and a brush having a specific resistance of 30000 μΩ · cm or more has been used. As a further increase in output and efficiency, it is considered effective to reduce brush electric loss with a large loss ratio in the loss configuration of the motor shown in FIG. If a brush with a small specific resistance is simply used to reduce brush electrical loss, the brush life can be ensured, and the length of the brush must be increased to ensure the life. However, a long brush leads to an increase in the brush friction loss (sliding loss between the brush and commutator) shown in FIG. 1. Although the brush electric loss is reduced, the brush friction loss increases, and the total improvement of each loss is not greatly improved. I could not expect. In other words, in order to achieve high efficiency, it is necessary to use a brush having a small specific resistance and to ensure the lifetime without increasing the brush length.

  In order to extend the life of the brush, it has been studied to eliminate rectifying sparks and reduce electrical abnormal wear by improving the rectifying characteristics.

  In Patent Literature 1, two coil groups having different rectification timings are arranged in one slot by winding processing called so-called different number windings, and a coil that ends rectification earlier by controlling the number of coils and later. A technique for improving electric motor efficiency and brush life by using a low resistance brush having a carbon specific resistance of 20000 μΩ · cm or less by making the rectified voltage uniform with the coil that has finished rectification to have good rectification characteristics.

  Patent Document 2 discloses a technique for improving the brush life by setting the ratio DA / DF between the outer diameter DF of the field core and the outer diameter DA of the armature core to 0.44 to 0.46.

  In Patent Document 3, θ2 (angle in the circumferential direction formed by the distance from the magnetic pole refracting portion to the tip of the magnetic pole tip) / armature slot pitch (angle between armature slots) and θ3 (arc gap tangent to the gap gap) On the other hand, a technique for improving the brush life and the motor torque by setting the value of the angle of the inclination of the magnetic pole tip to a range of 0.4 to 0.7 or less is disclosed.

  However, the above-mentioned known document does not describe the specific shape of the armature around which the armature winding for transmitting and receiving electricity through the commutator is wound, and as a result, satisfactory rectification characteristics cannot be obtained. It became clear.

JP 58-33960 A JP 2004-242471 A JP 2009-273237 A

  In the conventional technology, to improve the brush life, the commutation characteristics are improved by the technology to ensure commutation by twisting the windings, the ratio of the stator core to the armature core, and the shape of the stator core. Techniques to do so are disclosed. However, the shape of the armature that is in contact with the brush and integrated with the commutator that sends and receives electricity has not been studied. To make full use of a brush with low specific resistance, there is a problem in terms of brush life. It was.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a commutator motor, an electric blower, and an electric fan that ensure brush life characteristics by optimizing the shape of the armature when the efficiency of the commutator motor is increased by using a low resistance brush. To provide a vacuum cleaner.

  If the outer diameter of the armature is D, the diameter of the armature on the inner peripheral side of the slot formation position is Ds, and the variable corresponding to the specific resistance of the brush is defined as x, x ≦ Ds / D ≦ 0.67. It is characterized by satisfying. When the specific resistance of the brush is 10,000 μΩ · cm, x = 0.67, and when the specific resistance of the brush is 30000 μΩ · cm, x = 0.64, and the specific resistance of the brush is 30000 μΩ · cm to 10000 μΩ. -Between cm, x gradually increases from 0.64 to 0.67 as the specific resistance of the brush decreases.

  According to the present invention, when x ≦ Ds / D ≦ 0.67 is satisfied and the specific resistance of the brush is 10,000 μΩ · cm, x = 0.67, and when the specific resistance of the brush is 30000 μΩ · cm When x = 0.64, and the specific resistance of the brush is between 30,000 μΩ · cm and 10,000 μΩ · cm, x gradually increases from 0.64 to 0.67 in accordance with the decrease in the specific resistance of the brush. Wire inductance can be reduced, rectification characteristics can be improved, electrical abnormal wear can be reduced, and brush life can be improved. Furthermore, torque pulsation can be reduced, rectification characteristics can be improved, electrical abnormal wear can be reduced, and brush life can be reduced.

The figure which shows the loss item and ratio of the conventional electric motor. The figure which shows the structure of the electric blower using the commutator electric motor concerning this invention. The armature shape definition diagram concerning this invention. The relationship figure of brush specific resistance and a brush life when changing ratio of the armature core back diameter Ds concerning this invention, and the outer diameter D of an armature. Explanatory drawing which shows an example of the connection state of each coil in the armature winding of a commutator motor. The armature top view which shows an example of a commutator winding. The relationship figure of ratio of the armature core back diameter Ds and the outer diameter D of an armature, and the effective inductance of a rectifier coil. The relationship figure of brush specific resistance and coil | winding temperature when the ratio of the armature core back diameter Ds and the outer diameter D of an armature is changed. The torque waveform typical figure when the ratio of the armature core back diameter Ds and the outer diameter D of an armature is changed. The relationship figure of ratio of armature core back diameter Ds and the outer diameter D of an armature, and a pulsation torque ratio. The relationship figure of the ratio of the armature core back diameter Ds and the outer diameter D of an armature, motor efficiency, and a brush concerning this invention. The relationship figure of ratio of the armature core back diameter Ds and the outer diameter D of an armature, and brush specific resistance.

  In the conventional technology, to improve the brush life, the commutation characteristics are improved by the technology to ensure commutation by twisting the windings, the ratio of the stator core to the armature core, and the shape of the stator core. Techniques to do so are disclosed. However, the shape of the armature that is in contact with the brush and integrated with the commutator that sends and receives electricity has not been studied. To make full use of a brush with low specific resistance, there is a problem in terms of brush life. It was.

  In order to solve the above-described problems, the present invention has studied the reduction of commutation sparks, that is, electrical abnormal wear, which extremely shortens the life of the brush. To suppress abnormal electrical wear, the rectification characteristics may be improved. The reduction of the inductance of the rectifier coil is studied as an improvement of the rectification characteristics, and there is a correlation between the armature shape (ratio between the armature core back diameter Ds and the outer diameter D of the armature) and the inductance, which affects the brush life. I found out.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 2 shows a longitudinal sectional view of an electric blower used for a vacuum cleaner or the like. The electric blower 1 includes an electric motor 2 and a blower 3. The electric motor 2 includes a stator 7 in which a field winding 6 is wound around a stator core 5 fixed inside the housing 4, a bearing 8 a provided in the housing 4, and a bearing 8 b provided in the end bracket 9. The armature core 11 and the commutator 12 are fixed to the shaft 10 and the shaft 10 to be held, and the armature winding 14 wound in the armature slot 13 of the armature core 11 is connected to the commutator 12. It comprises a rotor 15 and comprises a carbon brush 16 that is electrically connected to the commutator 12 by mechanical contact, and a brush holder 17 that holds the carbon brush 16 and fixes it to the housing 4. The blower is formed integrally with a centrifugal fan 19 fixed to one end of the shaft 10 by a nut 18, a diffuser 20 that reduces the speed of the air flow emitted from the centrifugal fan 19 and recovers the pressure, and a diffuser 20 that guides the air flow into the electric motor 2. And a fan casing 22 that covers the centrifugal fan and the diffuser 20.

  The commutator 12 has commutator pieces 12 a on its circumferential surface, and each commutator piece 12 a is connected to the armature winding 14 in the rotor 15. The carbon brush 16 is pressed against the commutator 12 by the helical spring 23 and rubs against the commutator 12. Reference numeral 24 denotes a lead wire for connecting the carbon brush 16 to the external electrode, and is connected to a terminal (not shown) provided on the brush holder 17.

  When the electric blower 1 starts rotating, the rotor 15 rotates, and the centrifugal fan 19 fixed coaxially with the rotor 15 also rotates. When the centrifugal fan 19 rotates, air flows from the air intake port 25 of the fan casing 22, flows into the electric motor 2 through the centrifugal fan 19, the diffuser 20, and the return guide 21, and is discharged from the electric motor 2 while cooling the electric motor 2. The

  FIG. 3 is a view showing the armature core 11 of the present invention, and shows the definitions of the armature core back diameter Ds and the outer diameter D of the armature. Hereinafter, the ratio of the armature core back diameter Ds to the outer diameter D of the armature is defined as Ds / D. The cross section of the armature core 11 is circular. A plurality of (for example, twelve) armature slots 13 are formed on the outer periphery of the armature core 11. The inner peripheral side of the position where the plurality of armature slots 13 are formed is called an armature core back. For example, D is (about 40 mm). If the value of D is fixed, Ds / D increases as the value of Ds increases. As the value of Ds increases, the size of each armature slot 13 decreases. As the size of each armature slot 13 decreases, the number of turns (number of turns) of the armature winding 14 wound around each armature slot 13 decreases or the wire diameter of the armature winding 14 decreases. For example, if the wire diameter of the armature winding 14 is fixed, the number of turns of the armature winding 14 decreases as the size of each armature slot 13 decreases. The number of turns of the armature winding 14 is fixed ( For example, if the size of each armature slot 13 is reduced, the wire diameter of the armature winding 14 needs to be reduced.

  FIG. 4 shows the relationship between the brush specific resistance and the brush life. The horizontal axis represents the specific resistance of the carbon brush 16 (hereinafter referred to as “brush specific resistance”), the vertical axis represents the life of the carbon brush 16 (hereinafter referred to as “brush life”), and the value is 1.0 as the conventional example. Shown as a relative comparison. A conventional example will be described in detail later. Brush specific resistance refers to the electrical resistance per unit length. The carbon brush 16 is obtained by mixing and compressing carbon powder with copper or iron, and the brush specific resistance can be changed by changing the amount of copper or iron mixed or by mixing other materials. . Each plot shows Ds / D defined in FIG. The brush life with respect to the brush specific resistance when Ds / D is 0.60, 0.64, 0.67, and 0.70 is shown. Both are straight-up lines, that is, the theoretical result that the brush life becomes longer as the brush specific resistance increases. However, in the case of the carbon brush 16 having the same brush specific resistance, it has been found that the brush life is improved by increasing Ds / D. The reason will be described with reference to FIGS.

  As shown in FIG. 5, an armature winding 14 is wound around the armature slot 13 so as to secure a rectifying characteristic by applying a so-called different number of turns. In this embodiment, the number of commutator pieces 12a of the commutator 12 is 24, and the number of armature slots 13 formed in the armature core 11 is 12. Therefore, the number of coil groups of the armature winding 14 is As shown in FIG. 5, two first coils C1 and second coils C2 are wound around one armature slot 13, respectively. A winding method referred to as “different number winding” in FIG. 5 will be described. The rotation direction of the rotor 15 is an arrow direction, and the armature slot 13A includes two of the first coil C1A at the front of the rotation direction where the rectification ends first and the second coil C2A at the rear of the rotation direction where the rectification ends later. Two armature windings 14 are wound. Next, a first coil C1B and a second coil C2B are wound around the adjacent armature slot 13B, respectively, and sequentially wound in the same manner up to each armature slot 13C, 13D,. This is to improve the rectification characteristics, improve the life of the carbon brush 16, and improve the motor efficiency. In the first coil C1 and the second coil C2 in the same armature slot, at the moment when the first coil C1 finishes rectification, the adjacent second coil C2 has already started rectification, and the carbon brush 16 is short-circuited. For this reason, the mutual induction action of the 1st coil C1 and the 2nd coil C2 arises, the effective inductance becomes small at the end of rectification of the 1st coil C1, and the reactance voltage also becomes small.

  FIG. 6 is a schematic diagram illustrating an example of an armature winding. The first coil at the front of the rotational direction where the commutation is completed first with respect to the rotation is C1, and the second coil at the rear with respect to the rotational direction where the commutation is finished later is C2, and the 12 armature slots 13A to 13A Twenty-four first coils C1A, second coils C2A to first coil C1L, and second coil C2L are wound in 13L. The first coil C1A means a first coil that starts to be wound from the armature slot 13A. In the present embodiment, the first coil is located on the inner peripheral side, and the second coil is located on the outer peripheral side. Here, each armature slot 13 has a first coil C1 at the front of the rotation direction in which the rectification is finished first by rotation and a second coil C2 at the rear of the rotation direction in which the rectification is finished later.

  FIG. 7 shows the relationship between Ds / D and the effective inductance during rectification of the front first coil C1 and the rear second coil C2. As shown in the figure, when Ds / D increases, the effective inductance of the front coil and the rear coil decreases. That is, the rectified voltage becomes small and can be set smaller than a limit voltage (common name: spark voltage) that generates an arc. Therefore, it was found that abnormal electrical wear can be reduced.

  From the above, it was found that the ratio Ds / D between the armature core back diameter Ds and the armature outer diameter D may be set large in order to improve the rectification characteristics. However, increasing the armature core back diameter Ds decreases the slot area of the armature slot 13. In order to wind the narrow armature slot 13, it is necessary to reduce the coil wire diameter. When the wire diameter of the coil is reduced, the electrical resistance of the coil is increased, and the armature copper loss in the loss shown in FIG. 1 is increased. Furthermore, abnormal heat generation of the coil occurs due to an increase in copper loss. In general, the coil used in the vacuum cleaner is often E type having a heat resistance temperature of 120 ° C. in “JIS C 4003 heat insulation class and heat resistance evaluation” in consideration of cost and safety.

  FIG. 8 shows the relationship between the brush specific resistance and the armature winding temperature when Ds / D is changed. From FIG. 8, even if the brush specific resistance is changed, the winding temperature does not change much. However, the winding temperature rises as Ds / D increases from FIG. And when Ds / D was larger than 0.67, it was clarified that the heat generation temperature of the E-type coil exceeded 120 ° C. due to the heat generated by the coil having a thin wire diameter, and safety could not be ensured.

  FIG. 9 shows a typical torque waveform when the diameter Ds / D is changed. From FIG. 9A, when Ds / D = 0.72, the average torque is 0.2313 N · m, and the pulsation torque is 0.0803 N · m. Here, the magnitude of the pulsation torque is defined as (value of pulsation torque) / (value of average torque) × 100 [%]. In this case, the ratio of the pulsating torque is 34.7%. From FIG. 9B, when Ds / D = 0.64, the average torque is 0.2299 N · m, the pulsation torque is 0.0805 N · m, and the ratio of the pulsation torque is 35.0%. From FIG. 9C, when Ds / D = 0.50, the average torque is 0.2248, the pulsation torque is 0.0924 N · m, and the ratio of the pulsation torque is 41.1%.

  FIG. 10 shows the ratio of Ds / D and pulsation torque obtained in the same manner as in FIG. From FIG. 10, it was found that Ds / D = 0.64 has an inflection point. That is, in the region where Ds / D ≧ 0.64, the rate of change (decrease rate) of the pulsation torque ratio accompanying the decrease in Ds / D is small, but in the region where Ds / D <0.64, the magnetic flux in the core back portion. Is saturated, the leakage magnetic flux is increased, and the output torque is decreased. Therefore, the change rate (reduction rate) of the pulsation torque ratio accompanying the decrease in Ds / D is large. Furthermore, the saliency of the armature increases and the pulsation torque increases.

  When the pulsation torque is increased, the commutator 12 integrated with the armature core 11 and the shaft 10 jumps and the contact with the carbon brush 16 is deteriorated. As a result, a spark is generated between the carbon brush 16 and the commutator 12. Occurs, promotes electrical wear and shortens brush life.

  FIG. 11 shows the relationship between the ratio Ds / D between the armature core back diameter Ds and the outer diameter D of the armature, the brush life, and the motor efficiency. The horizontal axis represents the ratio between the armature core back diameter Ds and the outer diameter D of the armature. The first vertical axis is the motor efficiency, and the value is the relative display with the current value being 100. The efficiency 1 [p.u.] of the electric blower 1 corresponds to an improvement of 10 W in terms of the suction power of the vacuum cleaner, and has an effect of securing a stronger suction performance. The second vertical axis is the brush life, and the value is set as a relative display with the current value being 1.0.

  The current product has a specific resistance of 32400 μΩ · cm and Ds / D = 0.63. In the range where Ds / D is smaller than 0.64, the pulsation torque becomes large and is not suitable. In the range where Ds / D is larger than 0.67, the current density of the armature winding 14 becomes large, and the temperature rise is not suitable because it does not satisfy the heat resistance temperature of the insulating material. Therefore, it is necessary to satisfy at least 0.64 ≦ Ds / D ≦ 0.67. Hereinafter, characteristics when the brush specific resistance is changed in the range of Ds / D from 0.64 to 0.67 will be described. When the brush specific resistance is 5000 μΩ · cm, the motor efficiency is higher than the current one, but the brush life is less than 1.0 and lower than the current one. When the brush specific resistance is 10,000 μΩ · cm, the motor efficiency is higher than the current one, but only when Ds / D = 0.67, the brush life is 1.0, which is the same level as the current one, and Ds / D <0. At 67, the brush life is less than 1.0 and less than current. When the brush specific resistance is 30000 μΩ · cm, the motor efficiency and brush life are higher than the current range over the entire range. When the brush specific resistance is 20000 μΩ · cm, which is between 10000 μΩ · cm and 30000 μΩ · cm, the motor efficiency is higher than the current one, but the brush life may be lower or higher than the current depending on Ds / D. That is, with Ds / D = 0.653 as a boundary, when Ds / D <0.653, the brush life is smaller than 1.0 and below the current level, but when Ds / D ≧ 0.653, the brush life is from 1.0. Greater than current. When the brush specific resistance is 40000 μΩ · cm, the motor efficiency is smaller than 100 and lower than the current one, but the brush life is higher than the current one. That is, there is a range that can be established as a motor that is highly efficient and satisfies the brush life by optimizing the ratio Ds / D between the armature core back diameter Ds and the outer diameter D of the armature according to the change in the brush specific resistance. . When the brush specific resistance is 10,000 μΩ · cm, Ds / D is 0.67, and when the brush specific resistance is 20000 μΩ · cm, Ds / D is 0.653 or more and 0.67 or less. Is 30000 μΩ · cm, Ds / D is set to 0.64 or more and 0.67 or less (a range of a substantially triangular shape in the figure). That is, if x is a variable corresponding to the brush specific resistance, x ≦ Ds / D ≦ 0.67 needs to be satisfied according to the brush specific resistance. When the brush specific resistance is 10,000 μΩ · cm, x = 0.67, and when the brush specific resistance is 30000 μΩ · cm, x = 0.64, and the brush specific resistance is 30000 μΩ · cm to 10,000 μΩ · cm. In the meantime, x gradually increases from 0.64 to 0.67 as the specific resistance of the brush decreases.

  Further, according to FIG. 11, the difference in brush life between the brush specific resistances 40000 μΩ · cm and 30000 μΩ · cm is A, the difference in brush life between the brush specific resistances 30000 μΩ · cm and 20000 μΩ · cm is B, and the brush ratio. When the difference in brush life between the resistance 20000 μΩ · cm and 10000 μΩ · cm is C, the relationship of A ≧ B ≧ C is established. In addition, the difference in Ds / D between the brush specific resistances of 40000 μΩ · cm and 30000 μΩ · cm when satisfying the same brush life 1.0 as the current is (1), the brush specific resistances of 30000 μΩ · cm and 20000 μΩ · cm (2), Ds / D difference between the brush specific resistance 20000 μΩ · cm and 10,000 μΩ · cm (3), Ds between the brush specific resistance 10000 μΩ · cm and 5000 μΩ · cm When the difference of / D is (4), the relationship of (1) <(2) <(3) <(4) is established. Also, the difference in motor efficiency between the brush specific resistance of 40000 μΩ · cm and 30000 μΩ · cm is C, the difference in motor efficiency between the brush specific resistance of 30000 μΩ · cm and 20000 μΩ · cm is B, and the brush specific resistance is 20000 μΩ · cm and 10000 μΩ.・ If the difference in the motor efficiency between cm is a, the relationship of A≈B≈C≈ holds.

  FIG. 12 shows the relationship between the ratio of the armature core back diameter Ds and the outer diameter D of the armature and the brush specific resistance when the current brush life of 1.0 is satisfied. As shown in FIG. 4, when the brush specific resistance is 5000 μΩ · cm, Ds / D that satisfies the current brush life of 1.0 is about 0.68, and when the brush specific resistance is 10,000 μΩ · cm, The Ds / D satisfying 1.0 of the brush life of 1.0 is about 0.67, and when the brush specific resistance is 30000 μΩ · cm, the Ds / D satisfying the current brush life of 1.0 is about 0.64. When the specific resistance of the brush is 40000 μΩ · cm, Ds / D satisfying the current brush life of 1.0 is about Ds / D = 0.60. This is plotted as shown in FIG. 12, with the vertical axis representing the brush specific resistance and the horizontal axis representing Ds / D. In FIG. 12, each plot is close to a curve. According to FIG. 12, in the range where the brush specific resistance is 10000 μΩ · cm or more, it can be approximated by a straight line, but in the range where the brush specific resistance is reduced from around 10000 μΩ · cm, the gradient is changed and approximated by a curve. Therefore, when the brush specific resistance is between 30,000 μΩ · cm and 10000 μΩ · cm, x gradually increases linearly from 0.64 to 0.67 as the specific resistance of the brush decreases.

  This technique can be improved by increasing the armature core back diameter Ds without increasing the outer diameter D of the armature. In other words, it can satisfy the conditions for size reduction and weight reduction required for an electric motor for a vacuum cleaner.

In the above invention, the rotation speed of the electric motor is preferably in the range of 36000 to 50000 rotations / minute. This is a physical quantity indicating a change in magnetic flux per unit time of the coil inductance correlated with the rectification characteristics. Therefore, the higher the speed motor, the shorter the commutation time and the larger the inductance. In this embodiment, since 12 slots have a different number of windings, the commutation time is 6.94 × 10 ⁻⁵ [seconds] at 36000 revolutions and 5 × 10 ⁻⁵ [seconds] at 50000 revolutions. The amount is large, the inductance is large, and rectification failure is likely to occur.

  In the above invention, the number of turns of the first coil C1 is 10 times and the number of turns of the second coil C2 is 4 times, ie, 14 times, and the coil wire diameter of the armature is from 0.6 mm to 0.8 mmφ. preferable. This is because if the coil wire diameter is small, the coil resistance increases, abnormal heating of the coil occurs when energized, and the heat resistance temperature of the insulating coating is exceeded. On the other hand, to reduce the copper loss, the coil wire diameter may be increased while considering the slot area. However, when the ratio of the armature core back diameter Ds and the outer diameter D of the armature, which is the range of the present invention, is in the range of Ds / D from 0.64 to 0.67, the wire diameter is Coils with a diameter of 0.80 mm or more cannot be repaired in the slot.

  As described above, by managing the armature core back diameter Ds and the outer diameter D of the armature, it is possible to ensure the brush life even when a brush having a small specific resistance is used. Therefore, it is possible to achieve both reduction of brush electric loss of the commutator motor and securing of brush life, and it is possible to provide a commutator motor with high efficiency, long life, small size and light weight.

  It should be noted that the present invention can also be applied to winding methods other than the different number of windings.

DESCRIPTION OF SYMBOLS 1 Electric blower 2 Electric motor 3 Blower 4 Housing 5 Stator core 6 Field winding 7 Stator 8, 8a, 8b Bearing 9 End bracket 10 Shaft 11 Armature core 12 Commutator 12a Commutator piece 13, 13A-13L Armature Slot 14 Armature winding 15 Rotor 16 Carbon brush 17 Brush holder 18 Nut 19 Centrifugal fan 20 Diffuser 21 Return guide 22 Fan casing 23 Winding spring 24 Lead wire 25 Air intake C1A to C1L First coil C2A to C2L Second coil

Claims (6)

In a commutator motor comprising an armature provided with a plurality of slots on the outer periphery into which armature windings are inserted, and a brush for exchanging power with the armature,
When the outer diameter of the armature is defined as D, the diameter of the armature on the inner peripheral side of the slot forming position is defined as Ds, and a variable corresponding to the specific resistance of the brush is defined as x.
x ≦ Ds / D ≦ 0.67
The filling,
When the specific resistance of the brush is 10,000 μΩ · cm, x = 0.67,
When the specific resistance of the brush is 30000 μΩ · cm, x = 0.64,
The commutator motor is characterized in that, when the specific resistance of the brush is between 30,000 μΩ · cm and 10,000 μΩ · cm, x gradually increases from 0.64 to 0.67 as the specific resistance of the brush decreases. The commutator motor according to claim 1,
The armature winding is composed of a first coil and a second coil that are wound a plurality of times in the same slot,
The first coil is a front armature winding in the rotational direction where rectification ends first,
The commutator motor according to claim 1, wherein the second coil is an armature winding that is later commutated. In the commutator motor according to claim 1 or 2,
The commutator motor is characterized in that the rotation speed of the commutator motor is 36000 to 50000 rpm. In the commutator motor according to any one of claims 1 to 3,
A commutator motor, wherein the armature winding has a wire diameter of 0.6 mm to 0.8 mmφ.   An electric blower comprising the commutator motor according to any one of claims 1 to 4.   An electric vacuum cleaner comprising the electric blower according to claim 5.

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