JPH104642A - Motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor which can prqevent the deflection of a shaft and prevent the occurrence of vibration noise and drop in rotation efficiency, by enlarging magnetic attraction, going a direction opposite to the output shaft, with respect to a rotor core. SOLUTION: In a motor 1, which has a shaft 3 whose output shaft end 31 is projected from the end face of a motor case 2, a rotor core 4, equipped with a stacked core 41, and a magnet 9 opposite to its peripheral end face, the rotor core 4 is equipped with a magnetocollective core 45, jutting out from the stacked core 41 to the side of the output shaft 31 out of the axial direction of the shaft 3, and the center position t0 (magnetic center of core) of the height dimension of the rotor core 4 slips off greatly to the side of the output shaft 31, from the center position T0 (magnetic center of magnet) of the height dimension of the magnet 9.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a motor. More specifically, the present invention relates to a structure of a rotor core constituting a motor.

[0002]

2. Description of the Related Art In a conventional small DC motor with a brush,
As shown in FIG. 4, a rotor core 104 including a laminated core 141 fitted and fixed to a shaft 103 is configured in a motor case 102, and a core insulator 142 is provided on a salient pole portion configured in the laminated core 141. Via winding 14
3 is wound. The shaft 103 has a laminated core 141
It has a structure that protrudes from the upper end surface and the lower end surface of
Of these protruding portions, the upper end side of the shaft 103 is supported by the bearing 151 on the end face of the stator case 121, and the lower end portion of the shaft 103 is supported by the shaft receiving portion 152 (thrust bearing).

Here, the center position to '(core magnetic center) of the height dimension of the rotor core 104 is shifted toward the output shaft 131 from the center position To' (magnet magnetic center) of the height dimension of the magnet 109. And the deviation x ′ is
The height of the rotor core 104, the height of the magnet 109, and the gap between the upper edge of the magnet 109 and the upper edge of the rotor core 104 are t2 ', T', and t1, respectively.
′, It is expressed by the following equation: x ′ = (T ′ / 2−t1′−t2 ′ / 2) (1) Therefore, the rotor core 104 is positioned at the center position To of the height of the magnet 109 by an amount corresponding to the displacement x '.
′. Since the rotor core 104 is under its own weight, the output shaft 1
As long as the motor 101 is used with the 31 facing upward, the lower end of the shaft 103 is stably supported by the shaft receiving portion 152, and no abnormal noise is generated even when the shaft 103 rotates.

[0004]

However, in the conventional motor 101, when the attitude of the device on which the motor is mounted is changed and the output shaft 131 is directed downward, the own weight of the rotor core 104 is shifted toward the output shaft 131. Therefore, the center position to 'of the height dimension of the rotor core 104 and
The magnetic attractive force caused by shifting the height of the magnet 109 from the center position To 'is too small, and the load on the rotor core 104 is applied toward the output shaft 131. As a result, in the motor 101 of the type that does not apply a lateral pressure to the shaft 103, there is a problem that vibration noise and a decrease in rotation efficiency (energy efficiency) due to the shake of the shaft 103 occur. Therefore, the center position to 'of the height dimension of the rotor core 104 and the magnet 10
Although there is a method of enlarging the displacement x 'from the center position To' of the height dimension 9 of the motor 9, the height dimension of the motor 101 must be enlarged in order to enlarge the displacement x 'with the conventional structure. .

[0005] In view of the above problems, an object of the present invention is to provide:
By increasing the magnetic attraction toward the opposite side of the output shaft with respect to the rotor core, a motor that can prevent the shaft from swaying, and prevent the occurrence of vibration noise and reduction in rotational efficiency, etc. To provide.

[0006]

According to the present invention, there is provided a motor case, a shaft having an output shaft protruding from the motor case, and a salient pole configured to be rotatable together with the shaft. In a motor having a rotor core having a laminated core wound with a coil, and a magnet arranged in the motor case so as to face an outer peripheral end surface of the rotor core, the rotor core is formed of the shaft from the laminated core to the shaft. A magnetic flux collecting core extending only toward the output shaft portion in the axial direction, wherein a center position of a height dimension of the rotor core is closer to the output shaft portion than a center position of a height size of the magnet. It is characterized by. That is, in terms of the magnetic circuit, the magnetic center position in the height direction of the rotor core is closer to the output shaft portion than the magnetic center position in the height direction of the magnet.

[0007] In the present invention, by the amount of constituting the magnetic flux collecting core,
Since the center position of the height of the rotor core can be largely shifted toward the output shaft than the center position of the height of the magnet, the force for magnetically attracting the rotor core in the direction opposite to the output shaft ( Magnetic thrust) is large. Therefore,
In the motor according to the present invention, the load on the rotor core is not applied toward the output shaft even when the output shaft is in the downward state. Therefore, since the shaft rotates without swinging, no vibration noise is generated and the rotation efficiency is high. Moreover,
Since the magnetic flux collecting area is expanded by the amount of the magnetic flux collecting core, the rotational torque can be increased.

In the present invention, it is preferable that the suction force on the rotor core is equal to or more than its own weight.

In the present invention, the suction force on the rotor core is preferably in a range from two to four times the weight of the rotor core. With this configuration, in an electronic device such as a portable compact disk player equipped with a motor, when the output shaft portion is in a downward state, an acceleration of a magnitude that may be applied to the motor while being carried is applied to the motor. Then, the load of the rotor core is not applied toward the output shaft. In addition, to increase the attraction force on the rotor core, the magnetic flux collecting core must be increased. However, if the magnetic flux collecting core is unnecessarily increased, the rotor core becomes heavier and larger. Here, in the present invention, since the upper limit of the suction force to the rotor core is set to four times the own weight of the rotor core,
As long as the rotor core does not become unnecessarily heavy or large, the load on the rotor core is not directed toward the output shaft when normal acceleration is applied even when the output shaft is downward. .

In the present invention, a size of the magnetic flux collecting core projecting from the laminated core toward the output shaft portion is smaller than a height of the laminated core, and is one of a height of the laminated core. It is preferably larger than the dimension of / 2.

[0011]

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

FIG. 1 is a sectional view showing the structure of a small motor to which the present invention is applied.

In FIG. 1, a motor 1 is a small DC motor with a brush, and a motor case 2 is constituted by a stator case 21 whose lower end face is open and a side plate 22 closing the open end of the stator case 21. ing. The motor case 2 incorporates a rotor core 4 having a laminated core 41 fitted and fixed to the shaft 3, and the salient pole portion of the laminated core 41 is provided with a winding 43 via a core insulator 42. Is wound. The shaft 3 has a structure protruding from the upper end surface and the lower end surface of the laminated core 41. Of these protruding portions, the upper end side of the shaft 3 is supported by a bearing 51 on the end surface of the stator case 21, and The portion protruding from the end surface of the output shaft 21 is the output shaft portion 31. On the other hand, a commutator 6 is formed at a lower end portion of the shaft 3, and an arc extinguishing element 7 is mounted at a position adjacent to the commutator 6. A brush 81 extending from the brush holder 8 fixed to the side plate 22 is in contact with the commutator 6. A lower end of the shaft 3 is provided with a shaft receiving portion 52 (thrust bearing) integrally formed with the brush holder 8.
In a state supported by.

The magnet 9 is mounted on the inner surface of the stator case 21 so as to face the outer peripheral end surface of the laminated core 51. Here, the center position of the height dimension of the laminated core 41 is slightly shifted from the center position To (magnet magnetic center) of the height dimension of the magnet 9 toward the output shaft portion 31, and the laminated core 41 is accordingly shifted. Is attracted toward the center position To of the height of the magnet 9. That is, the suction force is applied to the laminated core 41 toward the opposite side (the side of the shaft receiving portion 52) from the output shaft portion 31. However, when the motor 1 is mounted on a portable device or the like, the output shaft 31 does not always face upward, and the output shaft 31 sometimes faces downward. In such a posture, the weight of the rotor core 4 is greater than the attraction force caused by the difference between the center position of the height dimension of the laminated core 41 and the center position T0 of the height dimension of the magnet 9, so that the shaft 3 Rotor core 4 when rotating
Is applied toward the output shaft portion 31, the shaft 3 shakes, and vibration noise is generated.

Therefore, in the present embodiment, a magnetic flux collecting core 45 is formed on the outer peripheral end face of the laminated core 41 so as to protrude in the axial direction of the shaft 3 so as to protrude as the output shaft portion 31. The outer peripheral end surface of the 45 is in a state of facing the magnet 9. The magnetic flux collecting core 45 is a portion of the plurality of core materials constituting the laminated core 41, in which the outer peripheral end portion of the core material laminated closest to the output shaft portion 31 is bent toward the output shaft portion 31. A winding 43 is wound around the salient pole portion via a core insulator 42. Therefore, in the motor 1 of the present embodiment, the height dimension of the rotor core 4 is enlarged by the amount of the magnetic flux collecting core 45.

That is, in the motor 1 of the present embodiment, the height dimension of the rotor core 4 including the magnetic flux collecting core 45, the height dimension of the magnet 9, and the gap dimension between the upper edge of the magnet 9 and the upper edge of the rotor core 4 are respectively set. Given t2, T, and t1, the deviation x between the center position to of the height dimension of the rotor core 4 and the center position To of the height dimension T of the magnet 9 is given by the following equation: x = (T / 2−t1−t2) /2)...Equation (2) Here, from the viewpoint of the conventional motor shown in FIG. 4, the gap dimension t2 between the upper edge of the magnet 9 and the upper edge of the rotor core 4 is equivalent to that of the magnetic flux collecting core 45.
Is the gap size t2 between the upper edge of the magnet 109 and the upper edge of the rotor core 104 in the motor shown in FIG.
, The deviation x between the center position to of the height of the rotor core 4 including the magnetic flux collecting core 45 and the center position To of the height of the magnet 9 is the same as that of the conventional motor shown in FIG. It is larger than the displacement x '. That is,
The center position to of the height dimension of the rotor core 4 (core magnetic center) is closer to the output shaft portion 31 than the center position To of the height dimension of the magnet 9 (magnet magnetic center) by the amount of the magnetic flux collecting core 45. Since the rotor core 4 is largely displaced, the rotor core 4 is placed on the side opposite to the output shaft 31 (the side of the shaft receiving section 52)
The force of magnetic attraction toward is large.

As shown in FIG. 2, the height dimension of the laminated core 41 of the rotor core 4 is b, and the magnetic flux collecting core 45
Is the height dimension of a, the height dimension b of the laminated core 41 is
When the relative size of the height dimension a of the magnetic flux collecting core 45 is changed, the magnitude of the force for attracting the rotor core 4 toward the side opposite to the output shaft 31 and the degree of the motor vibration at that time Changes as shown in FIG. That is, when the height a of the magnetic flux collecting core 45 is increased from 0 to a size corresponding to １ ／ of the height b of the laminated core 41, as shown by a solid line P in FIG. Is increased toward the side opposite to the output shaft portion 31, and the motor vibration is reduced as indicated by the dotted line Q in FIG. However, the height dimension a of the magnetic flux collecting core 45 is
If the height b exceeds 1, the height a of the magnetic flux collecting core 45
Is larger, the rotor core 4 is connected to the output shaft 31.
Is not larger than the magnetic flux saturation of the magnetic flux collecting core 45, and the motor vibration does not decrease. Therefore, the height dimension a of the magnetic flux collecting core 45 is approximately in a range that satisfies the following equation (3): b / 2 ≦ a ≦ b (Equation 3) with respect to the height dimension b of the laminated core 41. It is set as follows.

Moreover, the suction force on the rotor core 4 is
It is set in a range from twice to four times the own weight of the rotor core 4. With such a configuration, in an electronic device such as a portable compact disk player on which the motor 1 of the present embodiment is mounted, even if the output shaft portion 31 is in a downward state, an acceleration of a magnitude that may be applied during carrying is generated. At the position applied to the motor 1, the load of the rotor core 4 is
Don't go to the 1 side. Moreover, in order to increase the attraction force to the rotor core 4, the magnetic flux collecting core 45 must be enlarged. However, if the magnetic flux collecting core 45 is unnecessarily enlarged, the rotor core 4 becomes heavy and large. . Thus, in this example, the upper limit of the suction force to the rotor core 4 is set to four times the own weight of the rotor core 4, and the rotor core 4 is unnecessarily heavy and does not become large in a normal portable state. The load of the rotor core 4 is not applied to the output shaft 31 side.

As described above, in the motor 1 of this embodiment, the center position to of the height of the rotor core 4 (core magnetic center) is set to the center position To of the height of the magnet 9 by the amount of the magnetic flux collecting core 45. Since it can be largely shifted to the output shaft portion 31 side than the (magnet magnetic center), the force for magnetically attracting the rotor core 4 toward the side opposite to the output shaft portion 31 (the shaft receiving portion 52 side) is large. . Moreover,
This suction force exceeds the weight of the rotor core 4. Therefore, in the motor 1 of the present embodiment, even when the output shaft 31 is in the downward state, the rotor core 4 is magnetically attracted to the side opposite to the output shaft 31. Therefore, the shaft 3 rotates normally without swinging without applying any side pressure, so that no vibration noise is generated and the rotation efficiency is high. Further, since the magnetic flux collecting area is expanded by the amount corresponding to the configuration of the magnetic flux collecting core 45, the rotational torque can be increased.

Further, by setting the height a of the rotor core 45 to the range satisfying the expression (3) with respect to the height b of the laminated core 41, the size of the rotor core 4 is most effectively reduced. The suction force toward the side opposite to the output shaft 31 is increased. Therefore, since the rotor core 4 does not become unnecessarily heavy, in the motor 1 of the present embodiment, even if the output shaft 31 is turned downward, the rotor core 4 is
A state in which the magnetic core is magnetically attracted to the opposite side can be maintained, no vibration noise is generated when the rotor core 4 rotates, and the rotation efficiency is high.

[0021]

As described above, according to the present invention, the center position (magnetic center) of the height of the rotor core is higher than the center position (magnetic center) of the height of the magnet by the amount of the magnetic flux collecting core. Are also greatly shifted toward the output shaft. Therefore, according to the present invention, since the force for magnetically attracting the rotor core toward the opposite side to the output shaft portion is large, even when the output shaft portion is in the downward state, the load on the rotor core is smaller than the output shaft portion. Don't go for. Therefore, no vibration noise is generated when the rotor core rotates, and the rotation efficiency is high. Moreover, since the magnetic flux collecting area is expanded by the amount of the magnetic flux collecting core, the rotational torque can be increased.

[Brief description of the drawings]

FIG. 1 is a partial sectional view showing a structure of a motor to which the present invention is applied.

FIG. 2 is an explanatory diagram showing a relationship between a height dimension of a laminated core and a height dimension of a magnetic flux collecting core in a rotor core provided in the motor shown in FIG.

3 is a graph showing a relationship between a ratio of a height of a magnetic flux collecting core to a height of a laminated core of the motor shown in FIG. 1, and a suction force applied to a rotor core and a degree of motor vibration.

FIG. 4 is a partial sectional view showing a structure of a conventional motor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Motor 2 ... Motor case 3 ... Shaft 4 ... Rotor core 9 ... Magnet 31 ... Output shaft part 41 ... Laminated core 45 ... Magnetic flux collecting core 51 ... Bearing 52: Shaft receiving portion (thrust bearing) to: Center position of rotor core height dimension (core magnetic center) To: Center position of magnet height dimension (magnet magnetic center)

Claims (5)

[Claims] 1. A motor case, a shaft having an output shaft protruding from an end face of the motor case, a rotor core configured to be rotatable with the shaft, and provided with a laminated core having a coil wound around a salient pole. A motor disposed in the motor case so as to face an outer peripheral end surface of the rotor core, wherein the rotor core is stretched from the laminated core toward only the output shaft portion side in the axial direction of the shaft. A motor provided with a magnetic flux collecting core for projecting, wherein a center position of a height dimension of the rotor core including the magnetic flux collecting core is closer to the output shaft portion than a center position of a height dimension of the magnet. 2. A motor case, a shaft having an output shaft protruding from an end face of the motor case, a rotor core configured to be rotatable together with the shaft, and having a laminated core having a coil wound around a salient pole. A motor disposed in the motor case so as to face an outer peripheral end surface of the rotor core, wherein the rotor core is stretched from the laminated core toward only the output shaft portion side in the axial direction of the shaft. A motor provided with a magnetic flux collecting core for projecting, wherein a magnetic center position in a height direction of the rotor core including the magnetic flux collecting core is closer to the output shaft portion than a magnetic center position in a height direction of the magnet. 3. The motor according to claim 1, wherein the suction force on the rotor core is larger than the own weight of the rotor core. 4. The motor according to claim 1, wherein the suction force on the rotor core is in a range from twice to four times the weight of the rotor core. 5. The laminated core according to claim 1, wherein a size of the magnetic flux collecting core projecting from the laminated core is smaller than a height of the laminated core, and a height of the laminated core. A motor characterized by being larger than half the size.