KR20040032389A - Single-phase direct current brushless motor - Google Patents

Abstract

PURPOSE: A single-phase brushless DC(Direct Current) motor is provided to reduce the manufacturing process by employing a two-slot-structure stator and an inner rotor method. CONSTITUTION: A housing(10) is provided with metal bearings(21,22) interposed between an upper and lower central surfaces thereof. Both surfaces of a rotational shaft(20) are slip-supported on the metal bearings(21,22) of the housing(10) so as to be rotated. A rotor magnet(30) is formed on a circumference of the rotational shaft(20) and magnetized in two poles. A stator(40) is formed on an inner surface of the housing(10) to generate rotational force together with the rotor magnet(30) and serially connected to two slots. The housing(10) is formed on a surface of a lower portion of a circuit board(50). A hall sensor for determining polarity of the rotor magnet(30) is formed on a side of the circuit board(50).

Description

Single-phase direct current brushless motor

The present invention relates to a single-phase brushless DC motor, in particular, to overcome the problems of durability of the mechanical contact portion of the conventional brushless DC (DC) motor and the assembly process in the manufacturing process of the brush and commutator of advantages of the conventional brushless DC motor ( The present invention relates to a single-phase brushless DC motor having a simple structure, which can costly compete with a DC brush motor while maintaining a structure without a commutator.

In general, motors that generate driving force in electronic and mechanical devices are classified into AC motors and DC motors, and stepping motors that drive pulses in the anticorrosive manner. DC motors are widely used for variable speed driving and provide high starting torque, but are simpler in structure and cheaper than AC motors.

In the field of application, AC small motors are mainly used in home appliances such as refrigerators and air conditioners, and industrial machines including small machine tools and dedicated automation machines. In contrast, DC small motors include A, VIDEO, PRINTER, LDP, and Cassette CDP. It is used in a wide range of fields such as / V equipment, precision equipment such as watches and cameras, home appliances such as VCRs, shavers, and hair dryers, and office equipment such as data records, HDDs, and FDDs.

DC motors are typically classified into two types shown in the accompanying drawings, FIGS. 1 and 2. 1 is a cross-sectional view illustrating a typical DC brush motor, and FIG. 2 is a cross-sectional view illustrating a DC brushless motor.

Briefly explaining the configuration and operation of the conventional DC brush motor shown in Figure 1, a fixed magnet 4 is installed on the inner peripheral surface of the housing 3, the inner diameter of the fixed magnet 4 coil is wound around the core The rotor 5 which is an amateur coil unit is installed. And the rotating shaft (1) supported by the metal bearing (2) pressed in the upper and lower sides of the housing (3) is fixed to the rotor (5) through the center of the rotor (5). The coil of the rotor 5 is configured to receive a current through the commutator commutator 6 to the brush 7 connected to the external electrode 8.

When current flows through the external electrode 8 to the coil wound on the rotor 5, the coil is excited and a constant magnetic flux is generated, which causes the rotor 5 to be fixed by the electromagnetic force between the fixed magnet 4 and each other. It will rotate at speed. Accordingly, the rotating shaft 1 coupled to the rotor 5 is rotated at the same time by receiving the support of the metal bearing 2.

The DC brush motor is a problem in the durability of the mechanical contact portion consisting of a commutator and a commutator commutator and the assembly of the manufacturing process. In other words, when the brush and the commutator is subjected to friction, wear progresses, so that metal powder or graphite scatters and the life of the motor is reduced. In addition, wear progresses and a flash over phenomenon occurs due to the arc generated between the contacts, causing a risk of fire.

It is a DC brushless motor illustrated in FIG. 2 to solve the disadvantages of the DC brush motor as described above. 2 is a type of a conventional DC brushless motor, in which the mechanical contact portions of the commutator and the brush of the DC brush motor are replaced with semiconductors I.C. In other words, unlike the DC brush motor, the electronic contactless rectification is performed in place of the mechanical contact between the brush and the commutator.

In the contactless method, the magnetic brush or the optical method can be designed, but the DC brushless motor is generally made of a permanent magnet so that the magnetic flux from the rotor can be used when the Hall element is used to detect the position of the rotor.

In case of using Hall element as position detection sensor, it is not necessary to install special magnetic field and it is possible with simple structure. Therefore, the brushless motor employing the Hall element has an advantage that the motor configuration can be made small.

The brushless motors are classified into inner rotor type, outer rotor type, and disk rotor type.

The inner rotor type is a structure in which a rotating shaft is mounted on a magnet of a cylinder and it rotates in a drive coil. It is mainly used for frequent inversion and reverse rotation due to its low inertia and excellent controllability. .

In the outer rotor type, a rotor magnet is disposed in a form in which a stator (stator) part is inside and surrounds the stator part, but the inertia of the rotor, which is a rotor magnet, is increased and is not suitable for the purpose of repeating rapid operation. It is mainly used as turn table motor of record player and cylinder motor of VTR.

In addition, the driving method is particularly important for the brushless motor since it is directly related to the output power and the driving circuit. If the motor is as simple as possible and requires a drive circuit and a cheap product, the two-phase half-wave method is good.If the specifications regarding torque and rotation unevenness such as the reel motor or the laser motor scanner motor are strict, three-phase propagation The method is much preferred. Compared to the half wave method, the propagation method has a problem in that the driving circuit is complicated.

As shown in FIG. 2, in the DC brisiless motor, a stator 13, which is a coil unit, is installed in a housing 17, and a rotor 14 having a driving magnet 15 fixed to an inner circumference thereof is installed outside the housing 17. The rotary shaft 11, which is provided and supported and rotated by the metal bearing 12, is also configured integrally with the rotor 14. Reference numeral 16 denotes an external electrode.

When a current is applied to the stator 13 wound around the coil to generate a magnetic field and an electromagnetic force in the driving magnet 15, the rotor 14 rotates. The detailed configuration and operation of the conventional DC brushless motor is described in this technique. Since it is known to those skilled in the art, a detailed description thereof will be omitted.

DC brushless motor is brushless, so it is easy to design without noise, and has strong advantages against forward and reverse rotation. However, it is relatively disadvantageous compared to the DC brush motor shown in FIG. 1 attached to the convenience of control and the cost of the product according to the configuration of a separate control circuit due to the semiconductor IC.

On the other hand, in recent years, due to the sharp decline in the sales of SET products for DC motors, there is a demand for more severe price reduction than ever before. As a result, each motor manufacturer is strongly pursuing a reduction in the number of parts, the development of cost-effective new materials, and the reduction of manufacturing and production costs by simplifying the process.

This trend has led to the extreme simplification of DC brushless motors developed and marketed over the past 1980s and 2000s, such as the number of parts and structurally simplified products, such as sensorless brushless DC motors. The trend is also common in DC motors used in computer peripherals and digital A / V-related equipment.

Therefore, the development of a new type of DC brushless motor is required for the high speed, low vibration and low noise.

The purpose of the single-phase brushless DC motor according to the present invention, which is proposed to solve the above problems, is to overcome the problems of the durability of the mechanical contact portion of the conventional brushless DC motor and the assembly process in the manufacturing process. An advantage is to provide a single-phase brushless DC motor with a simple structure that can compete with a DC brush motor at a cost while maintaining a structure that does not have a brush and a commutator.

1 and 2 are cross-sectional views of a conventional DC motor.

3 is a cross-sectional view of a single phase brushless direct current motor according to the present invention.

4 and 5 are a plan view of the main portion excerpts showing various embodiments of the present invention.

<Explanation of symbols for the main parts of the drawings>

10 housing 20 rotation axis

21,22: Metal bearing 30: Rotor magnet

40: stator 50: circuit board

51: Hall element W: wire

Single phase brushless DC motor according to the present invention for achieving the above object, the housing, the metal bearing is interposed on the upper, lower center surface; A rotating shaft on both sides of which is rotatably supported on the metal bearing of the housing; A rotor magnet formed on an outer circumferential surface of the rotating shaft and bipolar magnetized; It is formed on the inner peripheral surface of the housing and generates a rotational force with the rotor magnet, the two slots connected in series; The housing is formed on one side of the lower, characterized in that it comprises a circuit board on one side is formed with a Hall element for determining the polarity of the rotor magnet.

One preferred feature of the present invention is that the rotor magnet is bipolar magnetized in a symmetrical state, and the first and second slots of the stator are formed in an asymmetrical structure.

Another desirable feature of the present invention is that the rotor magnet is asymmetrically bipolar magnetized, and the first and second slots of the stator are formed in a symmetrical structure.

Another preferable feature of the present invention is that the first and second slots of the stator are divided into split slot pairs connected in series.

Hereinafter, with reference to the accompanying drawings will be described in detail the configuration and operation of the present invention through a preferred embodiment of the present invention single-phase brushless DC motor.

3 is a cross-sectional view of a single-phase brushless DC motor according to an embodiment of the present invention, Figures 4 and 5 is a plan view of the main portion showing the various embodiments of the present invention.

As shown in FIG. 3, a single-phase brushless DC motor according to the present invention generally includes a housing 10, a rotating shaft 20, a rotor magnet 30, a stator 40, and a circuit board 50. It is composed of

Metal bearings 21 and 22 are interposed between upper and lower center surfaces of the housing 10, and the upper and lower sides of the rotation shaft 20 are slidably rotatably supported by the metal bearings 21 and 22.

The rotor magnet 30 is installed on an approximately center outer circumferential surface of the rotation shaft 20 to rotate together with the rotation shaft 20, and has a two-pole magnetization structure.

The stator 40 is fixedly installed on the inner circumferential surface of the housing 10 and includes a plurality of slots formed of a core and a coil wound thereon, that is, a first slot 41 and a second slot 42.

The coil wound on the core receives power from the outside through the wire (W), and the rotor magnet is a magnetic force due to the interaction of the magnetic flux generated by the current flowing in the coil with the magnetic flux generated by the rotor magnet 30 described above. 30) to rotate.

The circuit board 50 is installed on one side of the lower portion of the housing 10, and particularly, on one side adjacent to the lower portion of the rotor magnet 30, a hall element that determines the polarity of the rotor magnet 30; 51) is installed.

When the rotor magnet 30 rotates, the magnetic pole position of the rotor magnet 30 changes in response to the rotation, and the coil of the stator 40 corresponding to the magnetic pole position for continuous forward and reverse rotation of the rotor magnet 30 is rotated. Since the excitation of the rotor magnet (30) is required to detect the magnetic pole of the rotor magnet (30).

In the single-phase brushless DC motor, since the roles of the commutator and the brush are performed through the Hall element 51, which is a position sensor, the Hall element 51 senses the polarity of the rotating rotor magnet 30 and stator 40 according to the output. The current applied to the coils wound in the slots 41 and 42 of the c) is alternated, and the rotor magnet 30 is rotated forward and reverse by mutual electromagnetic force between the stator 40 and the rotor magnet 30.

In order to alternate the current applied to the first and second slots 41 and 42, a control circuit (not shown) for controlling the direction of the current is added according to the output of the hall element 51. It is preferable that the driving characteristics are appropriately configured to be good, and the semiconductor switching element such as a transistor and the driving unit connected to the hall element 51 to turn on / off the switching element and the like. In addition, amplification means for amplifying the output signal of the hall element 51 may be provided.

On the other hand, in a single-phase two-slot DC motor having such a configuration, one of the most important is initial self-starting that can be operated by itself initially.

In a single-phase motor, the torque becomes zero when the pole center of the rotor magnet coincides with the magnetic center of the stator core wound so as to generate an electromagnetic force so that starting does not occur.

In this state, the normal switching operation becomes difficult and the motor does not start even when the power is turned on.

In order to prevent such fire start, it is preferable to form the magnetic center of the stator core and the pole center of the rotor magnet differently. In particular, when the rotor is located at the initial startup, the magnetic pole detection by the Hall element is preferable, so that the rotor magnet should rotate.

4 and 5 show different embodiments of stator and rotor magnet structures with electromagnetic asymmetry so that such initial magnetic motions preferably occur.

In FIG. 4, the magnetization state of the rotor magnet 30 is bipolarly magnetized in a symmetrical state, and the first and second slots 41 and 42 of the stator 40 corresponding thereto are formed in an asymmetrical structure. The polarity of the rotor magnet 30 was asymmetrically polarized, and the first and second slots 41 and 42 of the stator 40 were formed in a symmetrical structure.

In order to show the electromagnetic asymmetrical structure, angles α and β, which are reference numerals of FIGS. 4 and 5, are represented by α <β so that the first and second slots 41 and 42 of the stator 40 in FIG. 4. ) Is an asymmetrical state, in FIG. 5, the polarity of the rotor magnet 30 is indicated as an asymmetrical state.

In this case, when the first and second slots 41 and 42 of the stator 40 are asymmetrically formed, split slot pairs 41a, 41b, 42a, and 42b connected in series to each other in order to obtain more effective initial magnetic motion. It is preferable to form.

The operation of the preferred embodiment of the single-phase brushless DC motor of the present invention configured as described above will be described.

The overall operation is when the power is applied to the stator 40 formed on the inner peripheral surface of the housing 10 through the wire (W), the rotation shaft (by the electromagnetic field between the stator 40 and the rotor magnet 30 on the rotation shaft 20) 20) rotates at high speed.

In more detail, first, the Hall element 51 installed in proximity to the rotating rotor magnet 30 senses the polarity of the rotor magnet 30 magnetized into two poles.

In general, the Hall element uses a kind of current magnetic effect called a Hall Effect, and has excellent properties compared to other devices in terms of detecting an electric field, strength of a magnetic field, and discriminating magnetic poles.

For example, when the Hall element 51 detects the N pole of the rotor magnet 30 and outputs a predetermined voltage to the control circuit installed on the circuit board 50, the predetermined transistor is turned on and the wire W is supplied from the power supply. Through the current flows to the coil wound in the first and second slots 41 and 42 of the stator 40.

On the coil side of the stator 40, magnetic poles are formed so that the rotor magnets 30 are preferably rotated by an applied current, and the magnetic poles generated in the two serially connected slots are the same as those of the two-pole magnetized rotor magnets 30. By pushing the pole to repulsion and pulling the opposite pole, the rotor magnet 30 operates to rotate stably.

At this time, the number of turns of the coil wound around the first and second slots 41 and 42 of the stator 40, the winding direction, and the current flow are such that the rotation of the rotor magnet 30 is preferably performed on the coil side of the stator 40. What is necessary is just to set it in consideration of the electromagnetic characteristic of the rotor magnet between 30.

Next, when the N pole is away from the Hall element 51 and the S pole is rotated into the Hall element 51 in the above process, the output of the Hall element 51 is changed. The control circuit controls on / off of the switching element according to the output of the changed Hall element 51. The transistor which is turned on is turned off and some other transistor is turned on so that the current flows in the opposite direction in the coil of the stator 40. Is approved.

By repeating the above process, the rotor magnet 30 is rotated stably at a constant torque and rotation speed.

When the stator 40 and the rotor magnet 30 are formed in an asymmetrical structure when the other side is symmetrical, as shown in FIGS. 4 and 5, initial driving is more preferable.

While the invention has been shown and described in connection with specific embodiments thereof, it is well known in the art that various modifications and changes can be made without departing from the spirit and scope of the invention as indicated by the claims. Anyone who owns it can easily find out.

As described above, the single-phase brushless DC motor according to the present invention has the following effects.

First, by molding in the simplest two-slot structure stator and inner rotor method there is an advantage that can simplify the manufacturing process and reduce the cost.

Second, the housing can be formed in a flat form, thereby making it possible to slim down.

Third, by having both the advantages of the conventional brush motor and brushless motor, there is an advantage to obtain a high-precision high rotational torque.

Fourth, the stator and the rotor magnets have an electromagnetic asymmetric structure, thereby eliminating the problem of initial magnetic incapacity, which is likely to occur in single-phase motors.

Claims (4)

A housing having metal bearings interposed at upper and lower center surfaces thereof; A rotating shaft on both sides of which is rotatably supported on the metal bearing of the housing; A rotor magnet formed on an outer circumferential surface of the rotating shaft and bipolar magnetized; A two-slot series-connected stator which is formed on an inner circumferential surface of the housing and generates a rotational force together with the rotor magnet; The housing is formed on one side of the lower side, one side brushless DC motor comprising a circuit board formed with a Hall element for determining the polarity of the rotor magnet on one side. The rotor magnet of claim 1, wherein the rotor magnet is bipolar magnetized in a symmetrical state. Single-phase brushless DC motor, characterized in that the first and second slots of the stator is formed in an asymmetrical structure. The method of claim 1, The rotor magnet is a two-pole magnetized in an asymmetrical state, the first and second slots of the stator is characterized in that the symmetrical structure is formed in a single-phase brushless DC motor. The method of claim 3, wherein The first and second slots of the stator are divided into split slot pairs which are connected in series with each other.