WO2012099235A1 - Clockwise and counterclockwise rotatable dc brushless motor - Google Patents

Abstract

[Problem] To provide a single-phase full-wave rectification-type or a two-phase half-wave rectification-type DC brushless motor which is controlled more easily and more inexpensively than when a three (or more)-phase brushless motor is clockwise and counterclockwise rotated, and which rotates in both clockwise and counterclockwise directions by a direct current without using a brush and a commutator. [Solution] To solve the problem, a single-phase full-wave rectification-type or a two-phase half-wave rectification-type DC brushless motor is provided with a position sensor for detecting the positions of the poles of a magnet serving as a rotor, controls the on/off of a switching element by the output of a magnetic pole detection signal from the position sensor, and changes the direction in which a current is passed through a coil wound around a stator. The configuration of the clockwise and counterclockwise rotatable DC brushless motor is characterized in that the rotor is counterclockwise rotated by interchanging two magnetic pole detection signals inputted from the position sensor to a circuit for controlling the switching element.

Description

DC brushless motor capable of forward and reverse rotation

The present invention relates to a single-phase full-wave rectification type or two-phase half-wave rectification type DC brushless motor that rotates in both forward (CW) and reverse (CCW) directions with a direct current (DC) current without using a brush and a commutator. About.

The DC brushless motor is obtained by replacing the functions of the brush and commutator of a conventional brush motor with a switching element such as a semiconductor and a control circuit for controlling the driving thereof. Compared with a brush motor, the DC brushless motor is superior in that it has a longer life, can be miniaturized, and can be assembled in a variety of shapes, and is highly efficient, easy to control, and driven quietly. For example, it is rapidly spreading to CD / DVD-ROM drives, hard disks, refrigerators, air conditioners and the like.

As shown in FIG. 1, the DC braless motor is used for a fan 1 that blows air to cool a heating element 3 such as an electric device that generates heat in accordance with a drive housed in a casing 2 such as a case or a container. Their uses are expanding. The fan 1 energizes the coil wound around the stator of the motor 1a in the forward and reverse directions, whereby the permanent magnet, which is a rotor, rotates, and the fin 1b rotates accordingly to form an air flow (wind). To do. The fin 1b is integrated with the rotor. The wind is sucked from the intake port 2a and exhausted from the exhaust port 2b. The rotor may be inside or outside the stator.

However, the conventional single-phase full-wave rectification type or two-phase half-wave rectification type DC brushless motor can be rotated only in one direction. Therefore, together with the wind sucked into the housing 2, dust such as dust and dust is accumulated over time in the slit 4 of the mesh, dust-proof net, etc. disposed on the wind inlet 2a or the wind of the fan 1, There were problems such as a decrease in cooling efficiency, a failure of the heating element, and a cause of ignition.

On the other hand, in the case of a three-phase DC brushless motor, the direction of rotation can be controlled by controlling the energization timing to the coil. For example, it is disclosed in Patent Document 1. By reversing the direction of rotation, the wind also flows in the opposite direction. Therefore, the dust accumulated in the slit 4 can be regularly scattered to reduce or prevent the accumulation of dust. In addition, such a three-phase DC brushless motor capable of forward and reverse rotation exhibits the same effect even in the case of local cooling inside the apparatus, not as a system fan that exhausts or intakes the entire inside of the apparatus. That is, in the case of local cooling, it is possible to reduce and prevent dust accumulated in the heat sink portion.

JP-A-6-70578

However, the 3-phase DC brushless motor, single-phase full-wave rectification type, on a higher manufacturing cost than the two-phase half-wave rectification type DC brushless motor, the control is complicated. In addition, the single-phase full-wave rectification type, two-phase half-wave rectification type DC brushless motor can be used for the following reasons even if the power supply +/- is connected in reverse or the existing circuit is reversed. It cannot be rotated in both directions from the outside.

FIG. 2 shows a conventional single-phase full-wave rectification type DC brushless motor 1c (a single coil is alternately energized with positive and negative currents (A)) and a two-phase half-wave rectification type DC brushless motor 1d (B: The cross-sectional schematic diagram of the bifilar winding) is shown.

N and S are the N pole and S pole of the magnet 6, and here, the combined product of the permanent magnet 6 and the magnet yoke 6a becomes the rotor. That is, when the motor is used as a fan motor, the fin 1b is connected to the combined product of the magnet 6 and the magnet yoke 6a.

The stator 5 has 4 poles and each pole has a T shape, and the tip of the T shape is called poles 5a and 5b. The stator 5 is fixed or integrally formed on the frame of the fan 1 or the like. In the hole of the stator 5, the rotating shaft 5c of the rotor including the magnet 6 is rotatably held.

Further, the coil 7 (7a) is wound around the shaft-like portion of the stator 5. The magnet 6 rotates by alternately applying a reverse current to the coil 7 (7a). Switching of the energization direction is controlled by sensing the position of the magnetic pole of the magnet 6 with a position sensor 8 fixed to the stator 5 and inputting the magnetic pole detection signal to a circuit (output path 10) for controlling the switch element.

When the motor is stopped, the start position of the position sensor 8 as go smoothly to arrange the position sensor 8 so as not come to the magnetic pole boundary 6b. The torque applied to determine the stop point of the motor is called cogging (cogging torque). If the stop point angle due to cogging is a 4-pole motor, it is designed to be 22.5 ° in the forward direction and the maximum value of cogging torque is ½ of the maximum torque generated by the magnet and coil when rotating. Ideal.

This 22.5 ° is an angle in a mechanical angle in which one rotation of the magnet 6 is 360 °. If the angle at which the magnet 6 rotates and the positional relationship of the magnetic poles reaches the same position as the original position is 360 ° in electrical angle, the mechanical angle is 180 °. The cogging angle is ideally 45 ° in electrical angle, and the cogging angle varies depending on the number of magnetic poles of the motor. For example, in a 2-pole motor, the electrical angle and the mechanical angle are the same, so the cogging angle is 45 ° even in the mechanical angle.

Next, FIG. 3 shows a block diagram of a conventional typical single-phase full-wave rectification type DC brushless motor drive IC. A position sensor 8 (H: Hall element) detects the magnetic pole of the magnet 6, and based on the magnetic pole detection signal, the direction of the current flowing through the coil 7 is reversed by driving the switching element 9 in accordance with the switching of the magnetic pole. IN + and IN- mean that if there is a magnetic pole, the output is output, and if there is no magnetic pole, both are not output. With respect to the middle of the applied voltage to the Hall element H, it is output as + and −, and the magnitude thereof is the same.

Next, FIG. 4 shows an ideal combined torque during normal rotation (forward rotation) in a conventional single-phase full-wave or two-phase half-wave rectification type DC brushless motor. Since the value of the torque obtained by synthesizing the magnetic torque and the cogging torque are located + in all angles, where it can be seen that the CW rotation without dead point be stopped.

On the other hand, FIG. 5 shows the combined torque when the conventional single-phase full-wave or two-phase half-wave rectification type DC brushless motor is set in the reverse rotation mode by an electric circuit. In this case, as is apparent from FIG. 5, there is a place where torque (in this case, CW torque) opposite to the rotation direction (in this case, the CCW direction) is generated, and a dead center is generated. Further, compared with the forward rotation, the fluctuation of the synthesized torque becomes very large, and the vibration of the motor is large, which is extremely problematic.

Next, the cogging torque and the stop point will be described with reference to FIG. Since the cogging torque is as shown in FIG. 6A, the sum is zero. Therefore, in a rotating motor, the motor torque at the time of forward rotation and reverse rotation has the same value. During reverse rotation, the torque during rotation does not become smaller.

Fig. 6 (B) shows a stable stop point, and Fig. 6 (C) shows an unstable stop point. The stable stopping point, returns to the stop point serves a torque in the CCW when the magnet 6 rotates in CW, are stable so returns to its original position as well as to rotate the CCW. The unstable stopping point, the magnet 6 torque of the same CW works the magnet 6 is rotated in the CW, will rotate and stops at the next stable stopping point.

As can be seen from the cross-sectional schematic diagram shown in FIG. 6 (B), it normally stops at a stable stop point (solid line circle in (A)), but the probability of stopping at an uneasy stop point is not zero. However, even if the motor stops at an unstable stop point (broken line circle in (B)) with a normal motor, the position sensor 8 is not positioned at the boundary of the magnetic pole of the magnet 6 and thus starts rotating without any problem.

The present invention is a single-phase rotating in both forward and reverse directions with a direct current without using a brush and a commutator, which is easier and cheaper to control than a DC brushless motor having three or more phases, which is forward and reverse. An object of the present invention is to provide a full-wave rectification type or a two-phase half-wave rectification type DC brushless motor.

In order to solve the above problems, the present invention includes (1) a position sensor that detects a pole position of a magnet that is a rotor, and controls on / off of a switching element by output of a magnetic pole detection signal of the position sensor, In a single-phase full-wave rectification type or two-phase half-wave rectification type DC brushless motor that changes the energization direction to a coil wound around the stator, two magnetic pole detection signals input from the position sensor to a circuit that controls the switching element The DC brushless motor can be rotated in the forward and reverse directions by rotating the rotor in the reverse direction. Also, (2) the DC capable of forward / reverse rotation according to (1), wherein the two magnetic pole detection signals are interchanged in conjunction with turning on or off of the motor driving power source or automatically by timer control. The configuration is a brushless motor.

(3) A position sensor for detecting the pole position of the magnet that is the rotor is provided, the on / off of the switching element is controlled by the output of the magnetic pole detection signal of the position sensor, and the energization direction to the coil wound around the stator is changed. In a single-phase full-wave rectification type or two-phase half-wave rectification type DC brushless motor, an energization path to the coil wound around the stator is automatically linked with turning on or off the motor driving power source or by timer control. It was set as the structure of the DC brushless motor which can perform forward / reverse rotation characterized by replacing.

(4) In a single-phase full-wave rectification type or two-phase half-wave rectification type DC brushless motor, two position sensors for detecting the pole position of the magnet as a rotor are provided, one for forward rotation and the other for reverse rotation. and use, and the signals by the forward and reverse rotatable DC brushless motor and controls the current direction of the coil wound around the stator arrangement from the position sensor. Also, (5) and the forward and reverse rotatable DC brushless motor structure according to the position sensor, characterized in that arranged offset from the center of the stator pole and the pole (4). Further, (6) switching the output of the magnetic pole detection signal of the forward rotation and reverse rotation position sensors to the switching element in conjunction with turning on or off of the motor drive power supply or automatically by timer control. The configuration of the DC brushless motor capable of forward / reverse rotation described in (4) or (5) is used.

(7) The configuration of the DC brushless motor capable of forward / reverse rotation according to any one of (1) to (6), wherein the cogging angle is set to 90 ° as an electrical angle.

Normal and reverse rotatable DC brushless motor of the present invention (hereinafter, sometimes simply referred to as "motor".), The arrangement of the rotor, the inner side of the starter may be either outside. The position sensors, although the Hall element can be exemplified, similar function, i.e., to detect the magnetic pole position of the magnet for example a permanent magnet, but is not limited to the Hall element if the output. In addition, the switching element includes a semiconductor. Further, the circuit only needs to add a mechanism for switching the input (hereinafter also referred to as an output path) to the circuit for controlling the switching element from the position sensor and a control circuit for controlling the same to the conventional circuit.

It is preferable that the rotation direction is not automatically changed by the operator, but is automatically linked to the normal operation of the operator. For example, an internal timer is provided in the control circuit of the mechanism that rotates in reverse for several tens of seconds, or switches the output path in conjunction with turning on or off the drive power source or fan of the heating element, and the rotation direction can be changed periodically. Alternatively, reverse rotation may be performed for a predetermined time after turning on / off the driving power source of the heating element. Of course, a mechanism that changes only the rotation direction of the motor as intended by the operator may be used. *

The present invention provides a single-phase full-wave rectification type or a two-phase half-wave rectification type DC by changing the output path from the position sensor to the switching element, or by changing the direction of energization of the coil wound around the stator. The brushless motor can be rotated in both forward and reverse directions. Therefore, it is possible to provide a single-phase full-wave rectification type or a two-phase half-wave rectification type DC brushless motor rotates easily and inexpensively in the forward and reverse bidirectional than 3-phase DC brushless motor.

Conventionally, when a fan that uses a motor that rotates only in one direction is used for cooling air to a heat generating part such as an electric device for a long time, there is a problem that dust accumulates in the suction part and the like, but the present invention solves that problem. can do. In particular, by interlocking with the on / off of the drive power supply of the electrical equipment, for example, when the drive power supply is turned off, the airflow in the opposite direction is kept until the motor stops by mechanically changing the connection of the output path in the reverse direction. It becomes possible, and the dust adsorbed on the suction part can be blown off. When the drive power supply is turned on next time, air blowing in the direction of blowing air to the heating element is performed by switching the connection of the output path. In conjunction with the driving of the electrical equipment, no special operation is required, and dust on the suction portion of the cooling air can be cleaned, which is convenient for the user.

In addition, by providing an internal timer in the motor control circuit, the timer can be rotated in the reverse direction for each predetermined driving time, thereby sufficiently cleaning the dust adsorbed on the suction portion. . By controlling the rotation direction of the motor by the timer method, it is possible to ensure an appropriate clean time according to the usage environment and the suction amount of the electrical equipment that generates heat.

By providing two position sensors, one for forward rotation and one for reverse rotation, it is possible to configure a motor that can rotate in both forward and reverse directions, and by adjusting the position of the position sensor, between the poles of the stator It is possible to eliminate the dead center of the motor by shifting it a little.

It is explanatory drawing of the usage example of a fan. It is a cross-sectional schematic diagram of a conventional DC brushless motor. It is a block diagram of the conventional DC brushless motor (FIG. 1 (A)). It is a figure which shows the ideal synthetic | combination torque at the time of normal rotation (forward rotation) in the conventional DC brushless motor. In a conventional DC brushless motor, it is a figure which shows the synthetic | combination torque when it sets to reverse rotation mode by an electric circuit. It is a figure which shows a cogging torque and a stop point. It is a block diagram of Example 1 (single phase full wave rectification type DC brushless motor). It is a block diagram of Example 2 (two-phase half-wave rectification type DC brushless motor). It is a block diagram of Example 3 (single phase full wave rectification type DC brushless motor / two position sensors). FIG. 6 is a schematic cross-sectional view of a DC brushless motor capable of forward and reverse rotation according to a third embodiment. It is a figure which shows the synthetic | combination torque at the time of forward rotation provided with two position sensors of Example 3. FIG. It is a block diagram of Example 4 (two-phase half-wave rectification type DC brushless motor / two position sensors). FIG. 10 is a schematic cross-sectional view of a DC brushless motor capable of forward and reverse rotation according to a fifth embodiment. It is a figure which shows the synthetic | combination torque at the time of the forward rotation which has arrange | positioned the position sensor of Example 5 shifted. Change EXAMPLE 6 / stator configuration, the combined torque by the rotation of the forward and reverse directions is a cross-sectional schematic view of a forward and reverse rotatable DC brushless motor has been modified so that the same waveform. It is a figure which shows the synthetic | combination torque and stop point at the time of forward / reverse rotation in the case of FIG. In FIG. 15, it is a figure which shows the change width | variety of the synthetic | combination torque at the time of forward rotation at the time of designing the maximum value of a cogging torque small. Example 7 / forward and reverse directions composite torque in the rotation of a cross-sectional schematic view of the forward and reverse rotation can be DC brushless motor of another embodiment changing the stator shape so that the same waveform.

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 7 shows a circuit block diagram of a DC brushless motor capable of forward and reverse rotation in the single-phase full-wave rectification type DC brushless motor according to the present invention. FIG. 7A shows the circuit connection during forward rotation, and FIG. 7B shows the circuit connection during reverse rotation.

In FIG. 3, the output path 10 of the magnetic pole detection signal, which is the position signal of the magnetic pole of the magnet 6 detected by the position sensor 8, is crossed (replaced), so that it can be rotated in both forward and reverse directions. The control circuit or the like is a conventional general single-phase full-wave rectification type or 2 except for a switching mechanism (mechanical connection or electrical connection) of the output path 10 and a control circuit (switching mode control circuit) for controlling the output path 10. This is the same as a phase half-wave rectification type DC brushless motor.

The timing of switching is automatically, periodically, or intentionally associated with the normal operation of the person, or with an internal timer, forced switch, etc. And it can reversely rotate at irregular intervals. If fan comprising such a motor, a wind for cooling is generated in the opposite direction, the scattering of accumulated dust, reduce dust, help prevent.

FIG. 8 shows a circuit block diagram of a DC brushless motor capable of forward and reverse rotation in the two-phase full-wave rectification type DC brushless motor of the present invention. FIG. 8A shows circuit connections during forward rotation, and FIG. 8B shows circuit connections during reverse rotation. The forward / reverse rotation control is the same as that of the conventional two-phase full-wave rectification type DC brushless motor except that the output path 10 of the magnetic pole detection signal from the position sensor 8 is replaced and a switching mode control circuit is provided. The switching mechanism of the output path 10 and the switching mode control circuit are the same as those in the first embodiment. same as below.

As shown in FIG. 9, the single-phase full-wave rectification type DC brushless motor can be rotated in the forward and reverse directions and easily controlled by providing the position sensor 8 and the second position sensor 8a for forward rotation and reverse rotation. FIG. 9A shows circuit connections during forward rotation, and FIG. 9B shows circuit connections during reverse rotation. Forward / reverse rotation can be achieved simply by switching the connection of the output path 10a as shown in FIG.

FIG. 10 is a schematic cross-sectional view of a DC brushless motor 11 capable of forward and reverse rotation in Example 3, and FIG. 11 shows the resultant torque. Note that in the case of Example 3, the position sensor 8, when the sensitivity of the second position sensor 8a is not good, switching the direction of current flow (switching) is delayed, the combined torque curve shown in FIG. 11. As a result, combined torque curve, that crosses the torque ratio 0 right edge (the dashed circle) is a stable stopping point (dead point), and the motor is thereby stopped. In this case, when energization is stopped, the rotor returns to a stable stop point and rotates by re-energization, but a later-described fifth embodiment can be exemplified as a more effective means.

As shown in FIG. 12, the two-phase half-wave rectification type DC brushless motor can be rotated forward and backward and easily controlled by providing two position sensors 8 and two second position sensors 8a for forward rotation and reverse rotation. FIG. 12A shows circuit connections during forward rotation, and FIG. 12B shows circuit connections during reverse rotation. Forward / reverse rotation can be achieved simply by switching the connection of the output path 10a as shown in FIG. The cross-sectional schematic diagram and the combined torque are the same as those in FIGS. 10 and 11 of the third embodiment.

In FIG. 13, the position sensor 8b (for CW rotation) and the second position sensor 8c (for CCW rotation) are not moved between the poles 5a and 5b, but are moved slightly in the switching direction at an early timing. A DC brushless motor 14 capable of reverse rotation is shown. Since two position sensors are arranged by shifting to a position to advance the switching timing, it is possible to prevent a “stable dead point” as in the case of the third embodiment, and to rotate in either forward or reverse rotation. Will never stop. Since the position sensor 8b for CW rotation and the second position sensor 8c for CCC rotation are separate parts, such control is possible.

FIG. 14 shows the combined torque in the case of FIG. By disposing the position sensors 8b and 8c in a direction that accelerates switching, there is no portion where the combined torque curve crosses the torque ratio 0 to the right, and there is no “stable dead point”. The part that crosses the torque ratio 0 in the upward direction becomes “unstable dead point (torque 0 point)”, and the motor does not stop at this position. At the “abrupt torque change point due to switching” (a point where the torque ratio crosses 0 vertically from top to bottom), the rotor starts vibrating and then rotates, so the motor does not stop.

When designing a CW and CCW bidirectional rotary motor with a single-phase full-wave rectification type DC brushless motor or a two-phase half-wave rectification type DC brushless motor, the "stable dead center" ”Is difficult, but by using two position sensors, a separate Hall element is used for each of CW and CCW rotations, making it easy to design without creating a“ stable dead point ”during energization become.

Next, FIG. 15 is changed to the stator 12a having a shape in which the notch 12b is provided in the stator 5 of FIG. 2, and a DC brushless capable of forward and reverse rotation with a cogging angle of 45 ° mechanical angle (electrical angle 90 °). A schematic diagram of the motor 12 is shown. The notch 12b is formed by recessing the center of both poles 5a and 5b of each pole of the stator 12a in a V shape in the direction of the rotation axis 5c. (The same applies to the stay fields 11a and 14a.) FIG. 15A shows a stable stop point, and FIG. 15B shows an unstable stop point. Reference numeral 6a is a magnetic pole boundary when stopped at a stable stop point, and reference numeral 6b is a magnetic pole boundary when stopped at an unstable stop point.

With such a shape, the combined torque during forward rotation in FIG. 16A and reverse rotation in FIG. 16B shows the same waveform.

Also, compared to the case where a conventional DC motor (FIG. 2) is adopted, the output path 10 can be replaced to reduce the torque fluctuation range of the combined torque during reverse rotation. Further, there is no angle at which negative torque (torque to rotate in reverse) is generated at all angles. In addition, as shown in FIG. 17, by decreasing the design the maximum value of the cogging torque, as in the combined torque of FIG. 17, it is also possible to reduce the fluctuation band.

However, if the cogging torque is made too small, the influence of mechanical friction cannot be ignored, so there is a possibility that it will not stop at a stable stop point when the motor is stopped, and it is necessary to adjust the design value by the motor to be designed. .

In general, the smaller the motor, the closer the cogging torque and the torque in the opposite direction, which are not allowed to rotate due to friction, become more difficult to stop at the stable stop point where it was originally desired to stop. Therefore, there is a limit to reducing the cogging torque.

If the cogging torque is not affected by friction and stops at the stable stop point shown in FIG. 15A, when the motor is energized, the electromagnetic torque generated at that time becomes maximum and the motor starts rotating smoothly.

On the other hand, the probability of stopping at an unstable stop point shown in FIG. Even when energized in the state of FIG. 15B, the electromagnetic torque is 0, so the magnet 6 may not rotate.

As a method of avoiding such danger, a circuit that intentionally reverses the coil energization direction when the motor is not rotating is provided by a mechanism that detects the rotation of the magnet built in the drive IC. When energized, a magnetic field torque is generated, and if the magnet is vibrated, it can be separated from an unstable stop point and rotated.

Next, in FIG. 18, similarly to the sixth embodiment, the cogging angle is 45 ° in mechanical angle (electrical angle 90 °), and the forward / reverse direction is provided with the stator 13 a of another form in which the combined torque in the forward / reverse rotation has the same waveform. A schematic diagram of the rotatable DC brushless motor 13 is shown.

When the stator 13a is stopped at a stable stop point, the tips of the poles 5a and 5b on the position sensor 8 between the poles 5a and 5b are cut out. That is, in the stator 5 of FIG. 2, the left and right two poles out of the four poles on the upper, lower, left and right sides are inverted to the line object. Even with this shape, the composite torque waveform is not shown here, but the composite torque waveform during forward and reverse rotation is the same waveform, and the torque fluctuation is the same as in the sixth embodiment, compared to the case where the conventional stator 5 is employed. The width becomes smaller.

DESCRIPTION OF SYMBOLS 1 Fan 1a Motor 1b Fin 1c Single phase full wave rectification type DC brushless motor 1d Two phase half wave rectification type DC brushless motor 2 Housing 2a Suction port 2b Exhaust port 3 Heating element 4 Slit 5 Stator 5a Pole 5b Pole 5c Rotating shaft 6 Magnet 6a Magnet yoke 6b Magnetic pole boundary
6c Magnetic pole boundary 7 Coil 7a Coil 8 Position sensor 8a Second position sensor 9 Switching element 10 Output path 10a Output path 11 DC brushless motor 11a capable of forward / reverse rotation Stator 12 DC brushless motor 12a capable of forward / reverse rotation Stator 12b Notch 13 DC brushless motor 13a capable of forward / reverse rotation, stator 14 DC brushless motor 14a capable of forward / reverse rotation, stator

Claims (7)

1. A single-phase all-phase sensor that includes a position sensor that detects a pole position of a magnet that is a rotor, controls on / off of a switching element according to an output of a magnetic pole detection signal of the position sensor, and changes an energization direction to a coil wound around the stator In wave rectification type or two-phase half-wave rectification type DC brushless motor,
   A DC brushless motor capable of forward and reverse rotation, wherein the rotor is reversely rotated by switching two magnetic pole detection signals input from the position sensor to a circuit for controlling the switching element.
2. 2. The DC brushless motor capable of rotating in the forward and reverse directions according to claim 1, wherein the two magnetic pole detection signals are interchanged in conjunction with turning on or off of a motor driving power source or automatically by timer control.
3. A single-phase all-phase sensor that includes a position sensor that detects a pole position of a magnet that is a rotor, controls on / off of a switching element according to an output of a magnetic pole detection signal of the position sensor, and changes an energization direction to a coil wound around the stator In wave rectification type or two-phase half-wave rectification type DC brushless motor,
   A DC brushless motor capable of forward and reverse rotation, characterized by switching the energization path to the coil wound around the stator in conjunction with turning on or off of a motor driving power source or automatically by timer control.
4. In a single-phase full-wave rectification type or two-phase half-wave rectification type DC brushless motor, two position sensors for detecting a pole position of a magnet as a rotor are provided, one for forward rotation and the other for reverse rotation. A DC brushless motor capable of forward and reverse rotation, wherein a direction of energization of a coil wound around a stator is controlled by a signal from the position sensor.
5. 5. The DC brushless motor capable of forward and reverse rotation according to claim 4, wherein the position sensor is arranged so as to be shifted from a pole of the stator and a center of the pole.
6. The output to the switching element of the magnetic pole detection signal of the position sensor for forward rotation and reverse rotation is automatically switched in conjunction with turning on or off of the motor drive power supply or automatically by timer control. A DC brushless motor capable of rotating in the forward and reverse directions according to claim 4 or 5.
7. The DC brushless motor capable of forward and reverse rotation according to any one of claims 1 to 6, wherein the cogging angle is 90 ° in terms of electrical angle.
   

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