KR20090086654A - Coreless type dc blushless motor - Google Patents

Abstract

A coreless BLDC motor is provided to control a stopping position of a rotor by generating the cogging torque in a distance close to a magnet. A case(8) and a bracket(1) form an outer shape of a BLDC vibrating motor. A stator includes a coil(3), a circuit board(2), and a shaft. The coil and the circuit board are arranged inside the bracket. A hall element and the driving circuit element are fixed to the circuit board. The shaft is fixed in the center of the bracket. The rotor includes a magnet(12), an eccentric weight(13), a rotation yoke, and a bearing. A part of the magnetic flux of the magnet flows to the case. The cogging torque generator is formed in the case to prevent the non-start point.

Description

Coreless Type Single Phase DC Brushless Motor {Coreless Type DC Blushless Motor}

The present invention relates to a single-phase drive type BLDC motor, and more particularly, to generate a cogging torque in a single-phase drive type flat vibration motor having an electrical starting point, so as not to stop at the starting point when stopping. The present invention relates to a BLDC motor in which rotational characteristics are stabilized by reducing fluctuations in rotational torque combined with an electrically generated torque. There may be several applications, but I will explain it as an example of a vibration generating motor used in mobile phones, PDAs, game machines, etc., which are recently increasing in usage.

In general, with the recent development of communication technology, one of the most widely distributed to the public is a mobile phone, a PDA, and the like. These devices are becoming smaller as they become smaller, making them portable as well as being able to exchange voice and data anywhere, anytime. Nowadays, not only vibrating function is required for public etiquette, but also the vibrating function is provided for game functions, which increases the demand for long-term lifetime guarantee. In addition, in general game consoles, when shooting a gun or hitting a ball in a sports game, and the like to generate vibrations, gamers began to provide a more realistic game. In all of these cases, a motor generating vibration is employed. In this case, the use of the vibration function increases the frequency of use of the motor, thereby increasing the life expectancy and high reliability of the motor.

The vibrating motor of the conventional brush type is limited in technically ensuring a long life because it involves the wear of contact parts such as brushes and commutators. In response, BLDC motors have emerged.

Such a BLDC vibration motor usually has a case at the top, a bracket at the bottom, a coil at the top of the bracket, and a driving circuit element fixed to the circuit board (PCB) to reassemble the bracket and fix the shaft at the center of the bracket. Construct the stator. Place the eccentric weight on the outside of the magnet and the magnet and assemble it with the rotating yoke and assemble the rotor with the sintered bearing in the center, and assemble the shaft and put a sliding washer between the bracket and the rotor to axially slide It guides the rotation and is rotatably guided to the rotor inner bearing and shaft in the radial direction. When a current flows through the stator's circuit board, a magnetic force is generated in the coil, and the magnetic force acts on the magnet of the rotor to generate rotational torque. The rotor generates vibrations during rotation due to the eccentric weight.

In constructing such a BLDC vibrating motor, in order to reduce the number of parts and to reduce the cost, it is usually used to use two coils of 90 degree angles on a 4-pole magnet or two coils of 60 degree angles on a 6-pole magnet. Single phase bipolar driving is generally employed. The problem at this time is that there is a point called the starting point, there is a position that does not generate a rotational torque even if electricity is flowing. To this end, the soft magnetic material is generally projected to a certain position on the bracket side, so that the stop is not stopped at the point where the rotation torque is not generated electrically by using the rotating cogging torque generated between the magnet and the soft magnetic on the rotor side. When applied, it is intended to be able to rotate at all times.

Conventional BLDC motors are made of soft magnetic protrusions at a certain position on the side of the bracket facing the magnet so as not to stop the motor at the starting point or by making holes at a certain position or using a nonmagnetic material only at a certain portion. Cogging torque is generated by the action of.

However, there are two problems with this method.

First, the suction force between the bracket and the magnet is attracted to the sliding washer between the rotor and the bracket, and this force acts as a sliding resistance so that the rotor is intended to stop at the intended position in the design, that is, not the starting point. It acts as a factor to get out of.

Secondly, the cogging torque uses the action between the magnet and the soft magnetic body on the bracket side, but there is a circuit board and a coil between the magnet and the bracket, so that it is difficult to close the distance and to precisely stop the rotor stop position. Gets harder.

Moreover, since the first factor is added, the above two factors may cause a deviation from the intention to place the rotor at an electric non-start point. In addition, if the motor is used for a long time, the stop position error becomes bigger when the garbage is gathered due to the wear caused by the sliding rotation under the magnet suction load around the sliding washer, resulting in a failure that does not rotate even when the power is applied. . The customer taps the product, which causes the rotor to move to a stationary position, causing the rotor to spin, and even worse if it is bad.

There are many variations, but a representative one is introduced.

Remove the part corresponding to the center of each magnetic pole to the rotating yoke made of soft magnetic material, and the magnetic flux passes through the case to reduce the suction force of the rotor to the bracket part, and the case at the part corresponding to the part removed from the rotating yoke When a means for generating a cogging torque is provided in the same manner as the protruding means, the position of the means is set to stop the stop position of the rotor when the rotor stops because no current flows through the coil.

The above design reduces the magnet attraction force in the axial direction to increase the stopping position accuracy and reduces the sliding washer wear, thus improving long-term reliability and generating cogging torque at a closer distance from the magnet. Therefore, it is possible to drastically improve the problem of starting failure, and as a result, it is possible to provide a stable and reliable motor.

It will be described with reference to the accompanying drawings.

The BLDC vibration motor constitutes the overall appearance by combining the upper case 8 and the lower bracket 1 in FIGS. 1 and 2, and the magnet 12 facing the coil 3 on the bracket 1. Connect the integrated circuit (4) having a Hall sensor (4a) for recognizing the N, S magnetic poles of the current to change the direction of the current to the circuit board (2), and then assembled to the bracket (1) and then bracket (1) In the center, the shaft 5 is fixed to form a stator. Place the eccentric weight 13 sintered and molded with a high specific gravity powder such as tungsten on one side of the magnet 12 and the magnet 12, and assemble the sintered bearing in the center by assembling it in the rotating yoke 11 composed of a soft magnetic material. 10) to assemble the rotor, assembled on the shaft (5) between the bracket (1) and the rotor with a sliding washer (6) between the case (8) and the sinter bearing bearing (10) assembled to the rotor Equipped with a washer (7) having a low sliding resistance and good wear characteristics to guide the axial sliding rotation, and radially guided to the rotor sintered bearing (10) and the shaft (5) to be rotatable. When current flows to the terminals 2a and 2b on the circuit board 2 of the stator, a current flows through the circuit 3 and a magnetic force is generated in the coil 3 through a circuit omitted in the drawing. 12) the rotational torque is generated. The rotor generates vibrations during rotation due to the eccentric weight 13.

In constructing such a BLDC vibrating motor, in order to reduce the number of parts and to reduce the cost, it is usually used to use two coils of 90 degree angles on a 4-pole magnet or two coils of 60 degree angles on a 6-pole magnet. Single phase bipolar driving can be employed. Referring to the case of using a 60-degree coil and a six-pole magnet it is possible to obtain a torque as shown in the electrical torque graph of Figure 3 by the single-phase bipolar winding method. The problem is that torque cannot be generated electrically at the positions (3) and (7), and this point is called a starting point. In other words, the single-phase motor needs a means to prevent the motor from being at this starting point at the time power is applied.

To this end, in one example of the present invention, the magnetic flux is partially removed by circularly removing, for example, a portion 11a corresponding to each of the six magnetic pole magnetic poles in the rotating yoke 11 of the soft magnetic material in which the magnet 12 is assembled. The suction force with the case 8 is caused to pass through the case 8 so as to relatively reduce the suction force with the bracket 1 and, for example, a circular protruding means (for example) in the case 8 at a position corresponding to the radial position thereof ( The phase is set so that the position of the projection means 11a stops at the stop position of the rotor when the position of the protruding means 11a is turned off while providing 6 places of 8a). In other words, it has to be in a specific position with respect to the integrated circuit 4 incorporating the coil 3 of the stator and the hall sensor 4a so as to have a phase relationship of the cogging torque of FIG. 3 to the electrical torque of FIG. In the case of using a coil and a six-pole magnet, the center of the projection means 8a on the case 8 can be set at a point 15 degrees away from the center of the coil 3. In this way, as shown in FIG. 3, a phase design can be performed, and a motor having less fluctuation in torque without stopping at the starting point can be realized.

Here, as a method of installing the protruding means 8a in the case 8, it is preferable not to add a separate part by deforming the shape of the case 8, but a separate part including the protruding shape is provided in the case 8. It is easy to see that the method of combining with is also within the scope of the present invention.

In addition, the method of leaking a part of the magnetic flux of the magnet 12 toward the case 8 uses a material having a relatively low permeabilty of the material used in addition to the above method of mechanically removing a part of the rotating yoke 11. The partial leakage of magnetic flux is also a lekfms application.

In these cases, the positional relationship in which the electric torque and the cogging torque are obtained in FIG. 3 is sequentially shown in the figure in FIG. 4. Referring to the state at position 1, the hall sensor 4a recognizes the N pole and supplies current to the two coils 3 counterclockwise and clockwise, respectively, and the two coils 3 are each N, Under the boundary between S, S, and N poles, both coils push the magnet 12 to the left, with protruding means 8a on the case 8 called the cogging plate and part removed from the rotating yoke 11a. Cogging torque generated between the magnetic flux of the magnet 12 pushes the magnet 12 to the right, but weaker than the electric torque, the magnet 12 is moved to the left.

In position 2, the electric torque is slightly weakened as the magnet 12 moves, but the cogging torque is smaller, so that the magnet 12 proceeds in the same direction.

In position 3, it becomes a so-called starting point position described above aberration, the position where electric torque cannot act, but at this time, the cogging torque pushes the magnet 12 to the left according to the design of the design.

In position 4, the Hall sensor 4a recognizes the S pole and alternately flows the current to the two coils 3 clockwise and counterclockwise. In this case, the two coils 3 are already S, N and N, respectively. In this case, both coils push the magnet 12 to the left, and the cogging torque does not affect the coil 12 to the left.

From the position 5 to the position 8, the electrical torque is generated sequentially by the current switching to the coil 3 by the Hall sensor 4a in the process from the position 1 to the position 4, and the cogging dog is also moved in the same direction from the starting point. It causes the rotation so that it can rotate continuously in one direction just by applying power.

In this way, the magnetic flux of the magnet 12 is leaked in the direction of the rotating yoke 11 to reduce the magnet attraction force in one axial direction, and the cogging torque is generated by using the leaked magnetic flux so as not to stop at the starting point. Single phase flat BLDC motor is very useful as a vibration generating motor in mobile phones, PDAs, game machines, etc., and the eccentric weight of FIG. 1 in applications where only rotational force is needed without the need for vibration intentionally, such as for high-end toys requiring long life. It is only necessary to utilize the design in the form except the sieve 13.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 shows a first embodiment of the present invention, and is a cross-sectional view of a axially fixed axial void coreless brushless vibration motor cut in the lateral direction.

2 is a circuit board assembly diagram of an integrated circuit component including a coil and a hall sensor.

3 is a diagram for explaining a cogging torque and a phase relationship to avoid an electric torque and a starting point.

FIG. 4 is a diagram illustrating an operation principle of a motor in detail showing the operation principle of FIG. 3 in sequence.

Claims (3)

The external structure is formed by the case and the bracket, and the coil, the hole element and the driving circuit element are fixed to the circuit board inside the bracket and integrated with the bracket, and the shaft is fixed to the center of the bracket to form the stator. In the single-phase brushless DC motor, which has a heavy body and is assembled like a rotating yoke and a rotor with a bearing assembled in the center, guided to a shaft to generate vibration during rotation. A vibration generating motor comprising a cogging torque generating means provided in the case so that a part of the magnetic flux of the magnet passes through the case and there is no starting point. The vibration generating motor of claim 1, wherein the structure is modified in a form in which a shaft is fixed to the rotor and a bearing for guiding the shaft is fixed to the stator. The DC brushless motor according to claim 2, which is configured to generate rotational power through the shaft without generating an additional vibration by not installing an eccentric weight.

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