JP4153504B2 - Skeleton type BLDC motor - Google Patents

Description

  The present invention relates to a skeleton type BLDC motor, and more particularly to a BLDC motor in which resonance noise is reduced by reducing cogging torque.

  7 is a perspective view of a conventional skeleton type BLDC motor, FIG. 8 is a cross-sectional view of a conventional skeleton type BLDC motor, and FIG. 9 is a cross-sectional view taken along the line BB of FIG. is there.

  As shown in these drawings, the conventional skeleton type BLDC motor is arranged with a stator 102 to which power is applied and an air gap on the inner peripheral surface of the stator 102, and rotates by interaction with the stator 102. The rotor 104 includes a rotor 104 and a rotating shaft 106 that is attached to the center of the rotor 104 and transmits the rotational force to the outside while rotating together with the rotor 104.

  A PCB 108 on which a drive circuit for driving the rotor 104 is mounted is installed on one side of the stator 102, and the PCB 108 is accommodated in a PCB cover 110.

  The stator 102 includes a stator core 116 in which a plurality of sheets are stacked and fastened by rivets, and a first pole shoe 112 and a second pole shoe 114 in which the rotor 104 is accommodated are integrally formed. A pair of fixed bobbins 118 and 120, and a pair of coils 122 and 124 wound around the pair of bobbins 118 and 120, respectively, to which power is alternately applied.

  The first pole shoe 112 and the second pole shoe 114 are symmetrical with respect to the rotation axis of the rotor 104 so that the rotor torque is not aligned at the zero position for the initial start of the rotor 104. Detent grooves 126 are respectively formed.

  As shown in FIG. 10, the rotor 104 is a disc-shaped magnet 130 having N poles on one side and S poles on the other side with reference to a magnetic pole separation line 128 formed in the radial direction from the center of the rotor 104. And a magnet frame 132 disposed on the inner peripheral surface of the magnet 130 and having the rotation shaft 106 fixed at the center thereof.

  The rotor 104 is accommodated in the motor housing 140, and a pair of bearings 142 and 144 that rotatably support the rotating shaft 106 are disposed in the motor housing 140.

  The PCB cover 110 is provided with a position detection sensor (not shown) for detecting the rotational position of the rotor 104, and this position detection sensor is housed in the sensor housing portion 136.

  Hereinafter, the operation of the conventional skeleton type BLDC motor configured as described above will be described.

  When power is applied to the motor, the position detection sensor detects the rotational position of the rotor 104 using information on the magnetic pole separation line 128 of the rotor 104, and based on the detected result, the pair of coils 122, A DC power supply is applied to any one of 124. Then, the stator core 116 is excited to rotate the magnet 130, whereby the magnet frame 132 to which the magnet 130 is attached rotates together, and the rotating shaft 106 fixed to the magnet frame 132 rotates.

  At the initial start-up, the rotor 104 is prevented from being aligned at the zero position by the detent groove 126 formed to have a relatively large air gap as compared to the first pole shoe 112 and the second pole shoe 114. Become.

  However, in the conventional skeleton type BLDC motor as described above, a cogging torque, which is a tangential force trying to move to an equilibrium state where the magnetic energy is minimized, is inevitably generated. The cogging torque is generated between the magnet and the first and second pole shoes regardless of the current.

  In addition, when the rotor magnetic pole separation line passes the detent groove due to the rotation of the rotor, the air gap between the rotor and the stator changes, thereby changing the magnetic flux density and generating not only the basic order but also higher order cogging torque, The higher-order cogging torque becomes a major cause of motor resonance noise, and there is a problem that noise increases in the motor.

  R & D to reduce noise using methods such as improving the magnet magnetization method or changing the magnet shape to reduce the excitation source in order to reduce the occurrence of cogging torque as described above However, when these methods are used, not only high order (4th order, 5th order ...) cogging torque but also basic order cogging torque is reduced, and a certain level of cogging torque is required. There is a problem that the performance of the motor is reduced.

  The present invention has been made to solve such problems of the prior art, and maintains the performance of the motor by reducing only the higher-order cogging torque among the cogging torque generated when the motor is driven. An object of the present invention is to provide a skeleton type BLDC motor that can reduce resonance noise.

  In order to achieve such an object, a skeleton type BLDC motor according to the present invention includes a rotor that is separated into an N pole and an S pole based on a magnetic pole separation line, and the rotor is disposed with an air gap therebetween. A stator having a first pole shoe, a second pole shoe, and a pair of detent grooves formed on the inner surface, and air gaps between the detent grooves at both ends of the rotor through which the magnetic pole separation line passes. In order to increase the air gap, an air gap forming portion having a shape removed from the circle by a predetermined width is formed.

  In the skeleton type BLDC motor according to the present invention, a magnetic pole separation line that separates the N pole and the S pole of the rotor is provided with an air gap forming portion in which both ends of the rotor are removed to form the stator. There is an effect that the resonance noise can be reduced by increasing the air gap between the detent groove and the high-order cogging torque.

  Hereinafter, preferred embodiments of a skeleton type BLDC motor according to the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a sectional view of a skeleton type BLDC motor according to the present invention, and FIG. 2 is a sectional view taken along line AA in FIG.

  As shown in the figure, a skeleton type BLDC motor according to the present invention includes a motor housing 10, a stator 12 that is fixed inside the motor housing 10 and to which power is applied, and an air gap on the inner peripheral surface of the stator 12. And a rotor 14 that rotates by interaction with the stator 12, and a rotating shaft 16 that is attached to the center of the rotor 14 and transmits the rotational force to the outside while rotating together with the rotor 14.

  A PCB 18 on which a drive circuit for driving the rotor 14 is mounted is installed on one side of the stator 12, and the PCB 18 is accommodated in the PCB cover 20. The PCB cover 20 is provided with a position detection sensor (not shown) for detecting the rotational position of the rotor 14, and this position detection sensor is housed in the sensor housing portion 52.

  The stator 12 includes a stator core 26 in which a plurality of sheets are stacked and fastened by rivets, and a first pole shoe 22 and a second pole shoe 24 in which the rotor 14 is accommodated are integrally formed. A pair of fixed bobbins 28 and 30 and a pair of coils 32 and 34 wound around the pair of bobbins 28 and 30 and supplied with power alternately are formed.

  The first pole shoe 22 and the second pole shoe 24 have a pair of positions at positions symmetrical with respect to the rotation axis of the rotor 14 so that the torque of the rotor is not aligned at a position of 0 for the initial startup of the rotor 14. Detent grooves 36 are respectively formed.

  A bearing 50 is mounted between the rotary shaft 16 and the motor housing 10 to support the rotary shaft 16 rotatably.

  As shown in FIG. 3, the rotor 14 is a circle composed of an N pole on one side and an S pole on the other side with reference to a magnetic pole separation line 40 that divides the rotor 14 into two parts across the center of the rotor 14. A plate-shaped magnet 42 and a magnet frame 44 fixed to the inner peripheral surface of the magnet 42 and having the rotating shaft 16 fixed to the center thereof are configured.

  Here, the rotor 14 is formed in a circular shape and includes a semicircular N pole and a semicircular S pole.

  In addition, air gap forming portions 60 having a shape obtained by removing the width T from the circular shape are formed at both ends of the rotor 14 through which the magnetic pole separation line 40 passes. The air gap forming portion 60 is formed such that the diameter L1 of the rotor 14 through which the magnetic pole separation line 40 passes is smaller than the diameter L of the rotor 14 that forms 90 ° with the magnetic pole separation line 40.

  Further, the air gap forming portion 60 gradually increases in diameter from the diameter L1 of the rotor 14 through which the magnetic pole separation line 40 passes to the diameter L side of the rotor 14 that forms 90 ° with the magnetic pole separation line 40. Preferably it is formed. And it is preferable that the air gap formation part 60 is eccentrically formed about 1 to 1.5 mm in the left / right direction from the center of the circle.

  Such an air gap forming portion 60 reduces a higher order cogging torque by forming a large air gap when the magnetic pole separation line 40 passes through the detent groove 36 formed in the stator 12.

  Hereinafter, the operation of the skeleton type BLDC motor configured as described above according to the present invention will be described.

  When power is applied to the motor, the position detection sensor detects the position information of the rotor 14, and the drive circuit detects one of the pair of coils 32 and 34 based on the result detected by the position detection sensor. Supply DC power to one. Then, the stator core 26 is excited and the rotor 14 is rotated by the interaction with the rotor 14.

  At this time, when the magnetic pole separation line 40, which is a separation line between the N pole and the S pole, passes through the detent groove 36 of the stator 12, the rotor 14 has the largest air gap formed by the air gap forming portion 60 formed in the rotor 14. Since a gap is provided, higher-order cogging torque components are reduced.

  Here, the above cogging torque is a tangential force that tends to move to an equilibrium state where the magnetic energy is minimum, and is generated by an air gap between the rotor and the stator regardless of the current. The energy change of the magnetic energy due to the change in the minute rotation angle becomes a sine wave, and the cogging torque of the high frequency component is effectively reduced, thereby reducing the resonance noise.

  FIG. 4 is a graph comparing the cogging torque when the rotor of the conventional skeleton motor and the rotor of the skeleton motor according to the present invention rotate 360 °.

  As shown in FIG. 4, compared with the measured value P of the cogging torque by the conventional rotor 104, the measured values Q and R of the cogging torque by the rotor 14 of the present invention are reduced by the cogging torque of the fourth or higher order of the high frequency component. I understand that.

  FIG. 5 is a graph comparing high-order cogging torques of the present invention and the prior art. The cogging torque B of the present invention is lower than the conventional cogging torque A, and in particular, the harmonic level is 4 or more. It can be seen that at a high level, the cogging torque of the present invention is reduced by more than 80% compared to the conventional case.

  FIG. 6 is a graph comparing the noise generated from the skeleton motor of the present invention and the conventional skeleton motor. It can be seen that the noise T of the skeleton motor of the present invention is significantly lower than the noise S of the conventional skeleton motor. .

1 is a cross-sectional view of a skeleton type BLDC motor according to the present invention. It is the sectional view on the AA line of FIG. FIG. 3 is a diagram showing details of the rotor of FIG. 2 of a skeleton type BLDC motor according to the present invention. It is a figure which shows the graph which compared the cogging torque of the motor of this invention, and the conventional motor. It is a figure which shows the graph which compared the high-order cogging torque of the motor of this invention, and the conventional motor. It is a figure which shows the graph which compared the noise of the motor of this invention, and the conventional motor. It is a perspective view of the conventional skeleton type BLDC motor. It is sectional drawing of the conventional skeleton type BLDC motor. It is the BB sectional view taken on the line of FIG. It is a front view of the rotor of the conventional skeleton type BLDC motor.

Explanation of symbols

10 Motor housing 12 Stator 14 Rotor 16 Rotating shaft 18 PCB
20 PCB cover 22 1st pole shoe 24 2nd pole shoe 26 Stator core 28, 30 Bobbin 32, 34 Coil 36 Detent groove 40 Magnetic pole separation line 42 Magnet 44 Magnet frame 60 Air gap formation part

Claims (3)

A rotor including a cylindrical magnet separated into an N pole and an S pole on the basis of a magnetic pole separation line; and a magnet frame fixed to the inner peripheral surface of the magnet and provided with a rotation shaft at the center thereof ;
The rotor is disposed with an air gap, and includes a stator having a first pole shoe, a second pole shoe, and a pair of detent grooves formed on an inner surface,
At both ends of the outer peripheral surface of the magnet through which the magnetic pole separation line passes, an air gap forming portion is formed for increasing the air gap between the detent groove so as to reduce higher-order cogging torque ,
The air gap forming portion is formed by removing predetermined portions from both ends of the outer peripheral surface of the magnet through which the magnetic pole separation line passes and removing the predetermined portion from the diameter of the rotor through which the magnetic pole separation line passes. toward the diameter side of vertical the rotor, so that the diameter becomes gradually larger, skeleton type BLDC motor, characterized in Rukoto formed elliptical. The air gap forming portion is formed to be smaller by about 1 to 1.5 mm along the magnetic pole separation line than an outer periphery of a perfect circle whose diameter is the diameter of the rotor perpendicular to the magnetic pole separation line. The skeleton type BLDC motor according to claim 1. The motor, skeleton type BLDC motor according to claim 1 or 2, characterized in that the two poles of a single-phase motor.

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