JPH0574175U - motor - Google Patents

Abstract

(57) [Summary] [Purpose] To improve the output efficiency of the motor. [Structure] Gap between the rotor 8 and the housing 1
It is a motor that holds the rotational position of the rotor 8 by generating a leakage magnetic flux in the. Of the bottom plate 9a of the rotor case 9,
The inner peripheral portion 9A is set to have a thickness that can saturate the magnetic flux of the magnet 10. The outer peripheral portion 9B is set to have a thickness that does not saturate the magnetic flux. A magnetic attraction plate 12 is embedded in a portion of the plastic housing 1 facing the inner peripheral portion 9A. Since no leakage magnetic flux is generated in the outer peripheral portion 9B, the amount of magnetic flux for generating torque increases on the stator 2 side. Therefore, since the rotational force of the rotor 8 at the portion away from the shaft 5 increases, a large amount of torque is generated. Leakage magnetic flux is generated in the gap on the inner peripheral portion 9A side, and a suction force is generated with the suction plate 12. With this suction force, the rotational position of the rotor 8 can be properly maintained, and the output power of the motor can be improved by reducing the braking force. In addition, the housing 1 can be formed of an inexpensive material, and the cost can be reduced.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a motor suitable for use in, for example, a headphone stereo.

[0002]

[Prior Art]

 For portable devices such as headphone stereos, downsizing and thinning of the devices are required due to the convenience of carrying them. Therefore, downsizing and thinning of motors are important factors. For this reason, flat head motors (magnetic flux motors) whose magnetic flux is parallel to the axis of rotation are often used as headphone stereo motors. Further, similarly to the above, due to the demand for size reduction and weight reduction, a method of fixing the rotor to the housing by utilizing the leakage magnetic flux of the magnet is adopted.

FIG. 4 is a cross-sectional view showing an example of a motor for a tape drive system mechanism. Reference numeral 2 denotes a stator coil which constitutes a part of the stator, and is arranged so as to face a rotor 8 described later. A plurality of stator coils 2 are arranged at a predetermined angular interval. The stator is fixed to a substrate (not shown).

Reference numeral 8 denotes a rotor, which includes a rotor case 9 and a magnet 10. The rotor 8 is fixed to one end of the pulley 6 so as to face the stator coil 2. A ring-shaped magnet 10 in which N poles and S poles are alternately magnetized is fixed to the bottom plate portion 9a of the rotor case 9. The magnet 10 is arranged so as to face the stator coil 2. The bottom plate 9a has a flat surface on the side opposite to the magnet 10 side.

A rotating yoke (yoke) 7 is fixed to the pulley 6 so as to face the stator coil 2. Reference numeral 5 denotes a shaft, which is held at the center of the housing 1 by a bearing portion 1A (illustrated in a simplified manner in the drawing) of the housing 1 described later and is rotatably supported. The movement of the shaft 5 in the axial direction (removal direction) is not restricted by the bearing portion 1A. However, as will be described later, since a magnetic attraction force is generated by the leakage magnetic flux of the magnet 10 and the position of the rotor 8 is held by this magnetic attraction force, there is no problem.

The pulley 6 fixed to the shaft 5 has a groove 6a formed at the other end along the circumferential surface. The belt 4 is hooked around the groove 6a and a tape drive system mechanism (not shown).

Reference numeral 1 denotes a housing that houses a rotor 8 formed of a silicon steel plate, a permalloy plate, or the like. The housing 1 has a circular shape, and the bearing portion 1A is arranged at the center thereof.

The yoke 7 and the magnet 10 of the rotor 8 face the stator coil 2 with a predetermined distance in a state where the shaft 5 is supported by the bearing portion 1A. Further, the bottom plate 9a of the rotor case 9 faces the housing 1 with a predetermined distance.

At the start, the rotor 8 is rotationally driven by an oscillator (not shown). Then, as the rotor 8 rotates, an electromotive voltage is generated in the stator coil 2. This electromotive voltage is switched to a current flowing through the plurality of stator coils 2 as a position detection signal and controlled.

Further, in this example, the bottom plate portion 9 a of the rotor case 9 is set to a thickness that does not saturate with the magnetic flux of the magnet 10, and the magnet 10 leaks into the entire gap between the rotor case 9 and the housing 1. It is configured to generate a magnetic flux. Moreover, the thickness of the gap or the bottom plate portion 9a is set so that the rotor 8 can be attracted to the housing 1. Then, a magnetic attraction force is generated by generating a leakage magnetic flux of the magnet 10, and the position of the rotor 8 is held by this magnetic attraction force. Therefore, according to this example, the rotor 8 can be held at a constant height position without the retaining member for the shaft 5. The tape drive system mechanism is driven by the rotation of the rotor 8.

[0011]

[Problems to be solved by the device]

 By the way, as described above, the magnetic attraction force is generated by generating the leakage magnetic flux of the magnet 10 over the entire gap between the rotor case 9 and the housing 1, and the position of the rotor 8 is held by this magnetic attraction force. Therefore, eddy current loss, hysteresis loss, etc. also occur near the outer circumference of the rotor case 9, and a breaking force is generated on the rotor 8. Therefore, the output efficiency of the motor is reduced.

In order to prevent hysteresis loss and eddy current, the housing 1 is made of a magnetic material such as a silicon steel plate or a permalloy plate which has a small residual magnetic flux, a high electric resistance and no hysteresis characteristics. It had to be formed, which made it expensive.

Therefore, the present invention aims to increase the output efficiency.

[0014]

[Means for Solving the Problems]

 In this invention, the rotor and the stator are arranged so as to face each other, and the housing is arranged on the opposite side of the magnet arranged in the rotor case of the rotor, and the leakage flux of the magnet is generated between the rotor case and the housing. In this motor, the magnetic attraction force is generated and the rotor position is held by this magnetic attraction force.The magnetic attraction part is configured only in the portion of the housing that faces the inner peripheral portion of the rotor case. is there.

[0015]

[Action]

 A magnetic attraction force is generated by the magnetic attraction portion 12 arranged so as to face the inner peripheral portion 9A of the rotor case 9 of the housing 1. Due to this magnetic attraction force, the rotor case 9 is held at a constant height position with respect to the housing 1. Further, the inner peripheral portion 9A side of the rotor case 9 is less affected by the brake due to the eddy current loss and the hysteresis loss than the outer peripheral portion 9B side where the distance from the rotation center of the rotor 8 is long. The output efficiency of the motor can be increased.

Further, even if there is a leakage magnetic flux in the outer peripheral portion 9B of the rotor case 9, since no magnetic attraction force is generated on the outer peripheral portion 9B side, braking due to eddy current loss or hysteresis loss does not occur on the outer peripheral portion 9B side. The output efficiency of the motor can be increased.

Further, since the magnetic attraction portion 12 is arranged only in the portion of the housing 1 facing the inner peripheral portion 9A of the rotor case 9, the other portion of the housing 1 can be formed of inexpensive plastic or the like, and the cost can be reduced.

[0018]

【Example】

 An embodiment of the present invention will be described below with reference to FIG. In this figure, parts corresponding to those in FIG. 4 are designated by the same reference numerals, and detailed description thereof will be omitted.

The bottom plate portion 9a of the rotor case 9 is formed in a stepped shape such that the inner peripheral portion 9A thereof has a small thickness and the outer peripheral portion 9B thereof has a large thickness. The inner peripheral portion 9A side is set to have a thickness that can saturate the magnetic flux of the magnet 10. Further, the thickness and range of the inner peripheral portion 9A are set so as to generate the leakage magnetic flux of the magnet 10 necessary for the rotor 8 to be attracted to the housing 1.

The outer peripheral portion 9 B side is set to have a sufficient thickness so as not to be saturated with the magnetic flux of the magnet 10.

In the housing 1, a ring-shaped magnetic attraction plate (permalloy plate or the like) 12 is embedded in a portion facing the inner peripheral portion 9A of the rotor case 9. The housing 1 is made of plastic or the like. The rest of the configuration is similar to the example of FIG.

In this example, the magnetic flux leakage of the magnet 10 is generated only on the inner peripheral portion 9A side of the bottom plate portion 9a of the rotor case 9 and is not generated on the outer peripheral portion 9B side. The leakage magnetic flux of the magnet 10 disappears on the outer peripheral portion 9B side of the case 9. Therefore, since the magnetic flux increases on the side of the stator coil 2, the amount of magnetic flux used for torque generation increases, and the rotational force of the rotor 8 at the portion away from the shaft 5 increases. Therefore, according to this example, more torque is generated in the motor.

Further, in this example, since the leakage magnetic flux necessary for the rotor 8 to be attracted to the housing 1 is generated on the inner peripheral portion 9A side of the bottom plate portion 9a of the rotor case 9, the inner peripheral portion 9A A magnetic attraction force is generated in the rotor 8 by the magnetic attraction plate 12 disposed so as to face the rotor 8, and the magnetic attraction force keeps the rotor 8 at a constant height position with respect to the housing 1.

The inner peripheral portion 9A side is less affected by the braking force due to the eddy current loss and the hysteresis loss than the outer peripheral portion 9B side where the distance from the shaft 5 is long. Therefore, according to this example, since the braking force is reduced, the output efficiency of the motor can be improved.

Further, according to the present example, since the magnetic attraction plate 12 is embedded in the portion of the housing 1 facing the inner peripheral portion 9A of the rotor case 9, the housing 1 can be formed of inexpensive plastic or the like, and the cost can be reduced. ..

Further, according to this example, adjustment of the magnetic attraction force of the rotor 8 is necessary by arbitrarily changing the thickness of the inner peripheral portion 9A of the rotor case 9 and the range (area) of the inner peripheral portion 9A. It is possible to easily obtain an appropriate suction force (required minimum suction force). The other actions and effects are similar to those of the example of FIG.

FIG. 2 shows another embodiment of the present invention. In this example, the magnetic attraction plate 12 is arranged so as to be close to the inner peripheral portion 9A side of the rotor 8 of the housing 1, and in addition to the bottom plate portion 9a of the rotor case 9, the surface facing the rotor 8 of the housing 1 is arranged. This is an example configured to have a stepped shape.

In this example, the inner peripheral portion 9A of the rotor case 9 and the magnetic attraction plate 12 are arranged so as to be close to each other, so that the attractive force for the rotor 8 increases and the inner peripheral portion for causing the leakage magnetic flux is increased. The area of the portion 9A can be reduced. Therefore, the area of the outer peripheral portion 9B can be increased, and thus more torque can be generated than in the example of FIG. The other operational effects are similar to those of the embodiment shown in FIG.

FIG. 3 shows still another embodiment of the present invention. In this example, an annular magnetic shield plate (for example, a permalloy plate) 15 is attached to the outer peripheral portion 9B of the bottom plate portion 9a of the rotor case 9. The magnetic shield plate 15 is set to have a sufficient thickness so that the outer peripheral portion 9B is not saturated with the magnetic flux of the magnet 10.

According to this embodiment, the same effect as that of the embodiment of FIG. 2 can be obtained by attaching the magnetic shield plate 15 of this embodiment to the conventionally used rotor case 9, so that the conventional product is effective. It can be used and its application range can be expanded.

Even if the rotor case 8 is constructed such that the entire surface of the bottom plate portion 9a thereof produces a leakage magnetic flux as in the conventional example, the present invention can be similarly applied.

[0032]

[Effect of the device]

 According to this invention, since the magnetic attraction portion is formed only in the portion of the housing that faces the inner peripheral portion of the rotor case, only the inner peripheral portion of the rotor case that is relatively less affected by the braking force is magnetic A suction force is generated and the output efficiency of the motor can be improved.

Further, according to the present invention, even if there is a leakage magnetic flux in the outer peripheral portion of the rotor case, the magnetic attraction force is not generated on the outer peripheral portion side, so the braking force is not generated on the outer peripheral portion side, and the output of the motor is reduced. The efficiency can be increased.

Further, according to the present invention, the other parts of the housing excluding the magnetic attraction part can be formed of inexpensive plastic or the like, and the cost can be reduced.

[Brief description of drawings]

FIG. 1 is a sectional view showing a main part of an embodiment.

FIG. 2 is a cross-sectional view showing the main parts of another embodiment.

FIG. 3 is a cross-sectional view showing the main parts of another embodiment.

FIG. 4 is a cross-sectional view showing a conventional example.

[Explanation of symbols]

 1 Housing 2 Stator Coil 7 Rotating Yoke 8 Rotor 9 Rotor Case 9a Bottom Plate 9A Inner Perimeter 9B Outer Perimeter 10 Magnet 12 Magnetic Suction Plate

Claims (2)

[Scope of utility model registration request] 1. A rotor and a stator are arranged so as to face each other, and a housing is arranged on the opposite side of the magnet arranged in the rotor case of the rotor, and the magnet leaks between the rotor case and the housing. In a motor in which a magnetic attraction force is generated by generating a magnetic flux and the rotor position is held by this magnetic attraction force, a magnetic attraction portion is provided only in a portion of the housing facing the inner peripheral portion of the rotor case. A motor comprising: 2. The thickness of the outer peripheral portion of the rotor case is
The thickness of the inner circumference of the rotor case is made thin so that it is not saturated with respect to the magnetic flux of the magnet, and the thickness of the inner circumference of the rotor case is thin so that it is saturated with respect to the magnetic flux of the magnet. The motor according to claim 1, wherein a magnetic attraction portion is formed in a portion facing the portion.