CN111886413A

CN111886413A - Electric fan

Info

Publication number: CN111886413A
Application number: CN201880091202.8A
Authority: CN
Inventors: 小野比出晴; 青木普道; 龟山正树; 北岛悠平; 安田芳彦; 七野一马
Original assignee: Mitsubishi Electric Corp
Current assignee: Mitsubishi Electric Corp
Priority date: 2018-03-29
Filing date: 2018-03-29
Publication date: 2020-11-03
Anticipated expiration: 2038-03-29
Also published as: CN111886413B; WO2019186859A1; TW201943185A; JPWO2019186859A1; TWI675531B

Abstract

The electric fan is provided with an impeller, a motor part for rotating the impeller, and a swing head mechanism for performing a swing head action for changing the direction of the motor part, wherein the swing head mechanism is provided with a stepping motor (3) which is provided with a stator (6), a motor shaft (8) arranged at the inner side of the stator (6), and a rotor (7) inserted into the motor shaft (8) with a gap between the rotor and the motor shaft (8), the stepping motor (3) rotates at a speed that the rotor (7) is pulled to the same side of the direction that the rotor (7) is pulled by an unbalanced magnetic attraction force, and the unbalanced magnetic attraction force is generated by the deviation of the motor shaft (8) from the center of the stator (6).

Description

Electric fan

Technical Field

The present invention relates to an electric fan equipped with a swing mechanism using a stepping motor.

Background

The stepping motor is useful for angle adjustment and rotation speed change of a member, and is used for member rotation in a plurality of fields.

In recent years, a stepping motor is used for a swing motion of an electric fan. The electric fan includes a blower for generating wind by rotating an impeller attached to a shaft of a motor. When air is blown by the blower, the blower is swung left and right in a wide range in which air is blown to the left and right, and is swung up and down in a wide range in which air is blown to the upper and lower sides of the mixing chamber.

Patent document 1 discloses an electric fan including a stepping motor for horizontal swing and a stepping motor for vertical swing, and which is configured to adjust the angle of the horizontal swing and the vertical swing.

Documents of the prior art

Patent document

Patent document 1: japanese patent No. 5786440

Disclosure of Invention

Problems to be solved by the invention

Since the rotor of the stepping motor is unbalanced in its own weight and the center of rotation and the center of gravity are deviated from each other, a centrifugal force generated during rotation becomes a force pulling the rotor in a radial direction. Therefore, the rotor of the stepping motor generally rotates along the outer periphery of a motor shaft provided inside the motor. Since the centrifugal force is generated in a direction from the rotation center toward the center of gravity, the direction of the centrifugal force changes according to the rotation angle of the rotor.

However, when the motor shaft is disposed offset from the center of the stator, the magnetic attraction force generated by the stator to rotate the rotor becomes unbalanced, and the rotor is attracted in a specific direction. When the unbalanced magnetic attraction force is stronger than the centrifugal force, the rotor is pulled when the centrifugal force acting on the rotating rotor and the unbalanced magnetic attraction force are directed in opposite directions. At this time, the rotor collides with an internal component such as a motor shaft or a stator, and thus 1 rotation generates 1 collision sound. Whether the rotor collides with the motor shaft or the stator depends on a gap between the rotor and the motor shaft and a gap between the rotor and the stator.

The electric fan using the stepping motor in the head swinging motion has the following problems: when the electric fan is operated in a swinging manner, the collision sound generated inside the stepping motor is amplified in the structure of the electric fan, and thus, noise which makes a user feel uncomfortable is generated.

The present invention has been made in view of the above circumstances, and an object thereof is to obtain an electric fan which prevents noise from being generated from a stepping motor during a swing operation.

Means for solving the problems

In order to solve the above problems and achieve the object, the present invention includes an impeller, a motor unit that rotates the impeller, and a swing mechanism that performs a swing operation that changes a direction of the motor unit. The head swing mechanism includes a stepping motor having a stator, a motor shaft provided inside the stator, and a rotor inserted into the motor shaft with a gap therebetween. The stepping motor is operated at a speed at which the rotor is rotated while being pulled to the same side as the direction in which the rotor is pulled by an unbalanced magnetic attraction force generated by the motor shaft being displaced from the center of the stator.

Effects of the invention

The electric fan of the invention has the effect of preventing the noise generated by the stepping motor when the swinging head is running.

Drawings

Fig. 1 is a view showing an external appearance of an electric fan according to embodiment 1 of the present invention.

Fig. 2 is an exploded view of the front and rear covers of the electric fan of embodiment 1.

Fig. 3 is a diagram showing the structure inside the base part of the electric fan according to embodiment 1.

Fig. 4 is a perspective view of a stepping motor for realizing the right and left swing mechanism of the electric fan according to embodiment 1.

Fig. 5 is an exploded perspective view of a stepping motor for realizing the right and left swing mechanisms of the electric fan according to embodiment 1.

Fig. 6 is a diagram showing a state where unbalanced magnetic attraction is generated in the stepping motor of the electric fan according to embodiment 1.

Fig. 7 is a diagram showing a state change in rotation of a stepping motor that realizes the right and left swing mechanisms of the electric fan according to embodiment 1.

Detailed Description

Hereinafter, an electric fan according to an embodiment of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the embodiment.

Embodiment mode 1

Fig. 1 is a view showing an external appearance of an electric fan according to embodiment 1 of the present invention. Fig. 2 is an exploded view of the front and rear covers of the electric fan of embodiment 1. Fig. 3 is a diagram showing the structure inside the base part of the electric fan according to embodiment 1. Electric fan 100 includes an impeller 101, a motor unit 102 for rotating impeller 101, a support 103 for supporting motor unit 102, and a base 104 for holding support 103 at the base of support 103. The impeller 101 is attached to a shaft of a motor of the motor unit 102. Electric fan 100 generates wind by rotating impeller 101 by the motor of motor unit 102. Electric fan 100 includes front and rear covers 1 and 2 that protect impeller 101 from the user's contact with rotating impeller 101.

The rear cover 2 is attached to the motor unit 102. The impeller 101 is disposed inside the rear shroud 2. A retainer 33 is attached to the rear shroud 2, and the front shroud 1 is assembled to the retainer 33, whereby the impeller 101 is covered and protected from the front and rear by the front shroud 1 and the rear shroud 2.

The motor unit 102 has a swing mechanism 105 driven up and down. The base portion 104 includes a swing mechanism 106 that is driven to the left and right by rotating the column portion 103. By combining the vertical swing mechanism 105 of the motor unit 102 and the horizontal swing mechanism 106 of the base unit 104, the user can set the air blowing direction. The air volume and the direction of the swing of electric fan 100 are operated by switch 104a provided in base 104. The air volume and the direction of the swing of electric fan 100 may be remotely controllable.

A stepping motor 3 is provided inside the base portion 104. The stepping motor 3 rotates a drive gear 4 attached to a shaft by the rotation of an internal rotor. The column part 103 is rotatably supported by the base part 104. A rotation gear 5 is attached to a lower portion of the column part 103, and when the drive gear 4 of the stepping motor 3 transmits a rotational force to the rotation gear 5, the column part 103 rotates. That is, stepping motor 3 and rotary gear 5 constitute right and left swing mechanisms 106 of electric fan 100. As support 103 rotates, electric fan 100 swings left and right.

Fig. 4 is a perspective view of a stepping motor for realizing the right and left swing mechanism of the electric fan according to embodiment 1. Fig. 5 is an exploded perspective view of a stepping motor for realizing the right and left swing mechanisms of the electric fan according to embodiment 1. A motor shaft 8 is fixed to the stepping motor 3 perpendicularly to the bottom surface 3b of the motor bracket 3 a. The rotor 7 having the permanent magnet provided on the surface of the cylindrical member is inserted into the motor shaft 8 with a gap therebetween. The rotor 7 includes a shaft 7a serving as an output shaft of the stepping motor 3. The rotation of the shaft 7a is transmitted to the drive gear 4 through the transmission mechanism 3 c. Since the rotor 7 is rotated in a state where the rotor 7 is inserted into the motor shaft 8 fixed to the motor bracket 3a, there is a gap between the inner diameter of the rotor 7 and the motor shaft 8. The rotor 7 rotates while generating centrifugal force and shaking during rotation due to imbalance of its own weight.

On the other hand, motor shaft 8 may be fixed to be offset from the center of stator 6 due to variations in manufacturing. When motor shaft 8 is displaced from the center of stator 6, a gap between the outer periphery of rotor 7 and the inner diameter of stator 6 is not uniform. Fig. 6 is a diagram showing a state where unbalanced magnetic attraction is generated in the stepping motor of the electric fan according to embodiment 1. As shown in fig. 6, when unbalanced magnetic attraction force is generated at the time of energization, a force in a specific direction strongly acts on the rotor 7.

Fig. 7 is a diagram showing a state change in rotation of a stepping motor that realizes the right and left swing mechanisms of the electric fan according to embodiment 1. Electric fan 100 of embodiment 1 reduces the rotational speed of rotor 7 to reduce the centrifugal force to prevent rotor 7 from being pulled by the magnetic attraction force. That is, the centrifugal force is reduced to make the magnetic attraction force larger than the centrifugal force, and the rotor 7 is rotated in a state of being pulled to the same side as the direction in which the magnetic attraction force is pulled. Since the rotor 7 rotates while being pulled to the same side as the direction in which it is pulled by the magnetic attractive force, the rotor 7 does not move abruptly and does not collide.

Fig. 7 also shows changes in the rotational state of the rotor 17 when the unbalanced magnetic attraction force is larger than the centrifugal force but the force difference is smaller. When the rotor 17 rotates at a high speed, the rotor 17 rotates along the outer periphery of the motor shaft 18, and rotates in a state where a gap is secured in a direction in which a centrifugal force acts. However, when the centrifugal force is directed in the direction opposite to the unbalanced magnetic attraction force, the centrifugal force no longer includes a component in the normal direction with respect to the unbalanced magnetic attraction force, and therefore, the rotor 17 is pulled toward the stator 16, and the rotor 17 collides with an internal component of the stepping motor such as the motor shaft 18 or the stator 16. The collision of the rotor 17 is a phenomenon that occurs when the centrifugal force is directed in the opposite direction to the unbalanced magnetic attraction force, and therefore, the collision of the rotor 17 occurs 1 time per 1 rotation.

Electric fan 100 according to embodiment 1 reduces the centrifugal force generated in rotor 7 by suppressing the rotation speed of rotor 7 per 1 minute to about 70 rpm. Centrifugal force is defined by F ═ mr ω²Therefore, when the rotor 7 and the rotor 17 have the same shape, the centrifugal force generated by the rotation of the rotor 7 at 70rpm is about 0.56 times the centrifugal force generated by the rotation of the rotor 17 at 100rpm, and the centrifugal force is reduced to a half. Therefore, the rotation speed of the rotor 7 is preferably between 50rpm and 100 rpm.

The collision sound generated by the collision of the rotor 17 is a phenomenon that occurs when the difference between the unbalanced magnetic attraction force and the centrifugal force is small. That is, the unbalanced magnetic attraction is a phenomenon that is generated when the rotor 17 has a force of a degree to rotate along the outer periphery of the motor shaft 18 due to the centrifugal force even when rotating, although the unbalanced magnetic attraction is larger than the centrifugal force. The centrifugal force generated by rotor 7 of stepping motor 3 of electric fan 100 according to embodiment 1 is more than half of the centrifugal force generated by rotor 17. Therefore, since the difference between the unbalanced magnetic attraction force and the centrifugal force of the rotor 7 is larger than that of the rotor 17, the rotor 7 is not rotated along the outer periphery of the motor shaft 8 by the centrifugal force any more, and the rotor 7 is rotated while being continuously pulled by the unbalanced magnetic attraction force at a predetermined position. Therefore, abrupt movement of the rotor 7 during rotation is avoided, and generation of collision noise due to collision of the rotor 7 is suppressed.

The reason why the rotor 7 rotates as described above is that a gap is provided between the rotor 7 and the motor shaft 8, and the gap between the rotor 7 and the motor shaft 8 is reduced as much as possible, thereby suppressing abrupt movement of the rotor 7. However, when the rotor 7 is a plastic molded product, dimensional variations of the rotor 7 are large, and it is difficult to strictly control the clearance on the inner diameter side of the rotor 7. Therefore, in the stepping motor 3 according to embodiment 1, the grease 9 is filled in the gap between the rotor 7 and the motor shaft 8 for both the purpose of reducing the impact sound of the rotor 7 and the purpose of smoothing the rotation of the rotor 7.

In addition, the cause of the centrifugal force generated in the rotor 7 is imbalance of the weight of the rotor 7 itself. In order to suppress the imbalance of the self weight of the rotor 7, it is necessary to improve the dimensional accuracy of the rotor 7. It is difficult to strictly control the clearance on the inner diameter side of the rotor 7, but it is easy to control the size of the outer diameter of the rotor 7. Therefore, in the stepping motor 3 according to embodiment 1, the size of the gap between the rotor 7 and the motor shaft 8 is equal to or smaller than the gap between the stator 6 and the rotor 7. Therefore, in the stepping motor 3, even if there is a sudden movement of the rotor 7, the rotor 7 does not collide with the stator 6. Further, by determining the size of the gap between the stator 6 and the rotor 7 in consideration of the variation in the stator 6 and the vibration of the rotor 7, the effect of reducing the occurrence of collision noise caused by the collision of the rotor 7 can be enhanced.

Since electric fan 100 according to embodiment 1 rotates rotor 7 while continuously pulling it by unbalanced magnetic attraction force, abrupt movement of rotor 7 during rotation can be avoided, and generation of collision noise due to collision of rotor 7 can be suppressed.

In the above description, electric fan 100 suppresses the generation of collision noise due to collision of rotor 7 in stepping motor 3 that realizes swing mechanism 106 in the left-right direction, but in the case where swing mechanism 105 in the up-down direction provided in motor unit 102 is realized by a stepping motor, the generation of collision noise can be suppressed by rotating the rotor while continuing to pull the rotor with unbalanced magnetic attraction force, as in stepping motor 3.

The configuration described in the above embodiment is an example of the contents of the present invention, and may be combined with other known techniques, and a part of the configuration may be omitted or modified within a range not departing from the gist of the present invention.

Description of the reference numerals

1, a front protective cover; 2, a rear protective cover; 3, a step motor; 3a motor support; 3b a bottom surface; 3c a transfer mechanism; 4 driving the gear; 5 rotating the gear; 6. 16 a stator; 7. 17 a rotor; 7a shaft; 8. 18 motor shaft; 9 lubricating grease; 33 a retainer; 100 electric fans; 101 an impeller; 102 a motor portion; 103 a pillar part; 104a base part; 105. 106 a head swinging mechanism.

Claims

1. An electric fan is characterized by comprising:

an impeller;

a motor unit that rotates the impeller; and

a swing mechanism for performing a swing operation for changing the direction of the motor unit,

the head swing mechanism includes a stepping motor having a stator, a motor shaft provided inside the stator, and a rotor inserted into the motor shaft with a gap therebetween,

the stepping motor is operated at a speed at which the rotor is rotated while being pulled to the same side as a direction in which the rotor is pulled by an unbalanced magnetic attractive force generated by the motor shaft being deviated from the center of the stator.

2. The electric fan according to claim 1,

the motor is provided with grease filled in a gap between the rotor and the motor shaft.

3. The electric fan according to claim 1 or 2,

the gap between the rotor and the motor shaft is below the gap between the stator and the rotor.

4. The electric fan according to any one of claims 1 to 3,

the rotational speed of the rotor is between 50rpm and 100 rpm.