JP2010098887A - Brushless motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve detection precision of a rotation position of a rotor. <P>SOLUTION: In a brushless motor, detection units 16U, 16V, 16W are provided in opposition to teeth 24U2, 24V2, 24W2 in the respective phases, and disposed at positions where polarities are switched according to changes in the direction of leakage magnetic flux from a rotor magnet 26 when windings 22U2, 22V2, 22W2 are brought into a non-conductive state. Moreover, a control unit 18 switches the conductive states of a plurality of windings 22U1 to 22W2 based on output signals from the detection units 16U, 16V, 16W so that the windings 22U2, 22V2, 22W2 are brought into the non-conductive state when the polarities of the detection units 16U, 16V, 16W are switched. According to this configuration, the effect of magnetic flux from a stator 12 to the output signals of the detection units 16U, 16V, 16W can be reduced, thereby improving the detection precision of the rotation position of the rotor 14. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a brushless motor, and more particularly to a brushless motor configured to detect a leakage magnetic flux from a rotor magnet in order to detect a rotational position of a rotor.

Conventionally, as this type of brushless motor, for example, there is the following (for example, Patent Document 1). That is, in the brushless motor described in Patent Document 1, a detection element is provided opposite to an exposed portion of the rotor magnet from the rotor yoke, and the leakage flux of the rotor magnet is detected by this detection element.
JP-A-8-172863 (FIG. 1)

  However, in the brushless motor described in Patent Document 1, when the detection element detects the leakage magnetic flux of the rotor magnet, the magnetic flux from the stator is superimposed on this leakage magnetic flux, and the detection accuracy of the rotational position of the rotor is reduced. There is a risk of doing.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a brushless motor capable of improving the detection accuracy of the rotational position of the rotor.

  In order to solve the above-mentioned problem, a brushless motor according to claim 1, wherein a stator having a plurality of windings and a plurality of teeth each wound with each of the windings, and the stator is arranged in a radial direction. A rotor having a rotor magnet, and any one of the plurality of teeth and at least one of the motor radial direction and the motor axial direction is provided to respond to a change in the direction of leakage magnetic flux from the rotor magnet. And detecting the output signal from the detection unit and winding the teeth facing the detection unit when the polarity of the detection unit is switched. A control unit that switches energization states of the plurality of windings based on the output signal so that the wound windings are in a non-energization state.

  In the brushless motor according to the first aspect, when the energization state of the plurality of windings is sequentially switched by the control unit, the rotor is rotated by receiving the rotating magnetic field from the stator. Further, when the rotor is rotated, a detection unit provided to face at least one of the teeth in the motor radial direction and the motor axial direction from among the plurality of teeth according to the direction of the leakage magnetic flux from the rotor magnet. Signal is output. Then, based on the output signal output from the detection unit, the control unit switches the energization state of the plurality of windings, and thereby the rotor is rotated at a predetermined rotational speed.

  Here, in the brushless motor according to claim 1, the control unit described above detects the winding wound around the teeth facing the detection unit when the polarity of the detection unit is switched so as to be in a non-energized state. The energization states of the plurality of windings are switched based on the output signal from the unit.

  Therefore, when the output signal from the detection unit changes according to the switching of the polarity, no magnetic flux is generated from the winding wound around the teeth facing the detection unit, so the magnetic flux from the stator to the output signal The influence of can be reduced. Thereby, the detection accuracy of the rotational position of the rotor can be improved.

  In addition, in the brushless motor according to claim 1, when the plurality of windings constitute a U phase, a V phase, and a W phase, as described in claim 2, the detection unit includes the U phase, The teeth in each phase of the V phase and the W phase are provided to face at least one of the motor radial direction and the motor shaft direction, and the control unit is configured to switch the U phase when the polarity of the U phase detection unit is switched. When the polarity of the V-phase detection unit is switched, the V-phase winding is de-energized, and when the polarity of the W-phase detection unit is switched, the W-phase winding is switched. It is preferable that the energized state of the plurality of windings is switched so that is in a non-energized state.

  In order to solve the above-mentioned problem, the brushless motor according to claim 3 is a stator having a plurality of windings and a plurality of teeth each wound with each of the windings, and is opposed to the stator in a radial direction. And a rotor having a rotor magnet arranged in a manner opposed to at least one of the teeth and at least one of the motor radial direction and the motor shaft direction, and the winding wound around the facing teeth. From the detection unit, a detection unit that is arranged at a position where the polarity is switched according to a change in the direction of the leakage magnetic flux from the rotor magnet when the wire is in a non-energized state, and outputs a signal corresponding to the polarity And a control unit that switches energization states of the plurality of windings based on the output signal.

  In the brushless motor according to the third aspect, when the energization state of the plurality of windings is sequentially switched by the control unit, the rotor is rotated by receiving the rotating magnetic field from the stator. Further, when the rotor is rotated, a detection unit provided to face at least one of the teeth in the motor radial direction and the motor axial direction from among the plurality of teeth according to the direction of the leakage magnetic flux from the rotor magnet. Signal is output. Then, based on the output signal output from the detection unit, the control unit switches the energization state of the plurality of windings, and thereby the rotor is rotated at a predetermined rotational speed.

  Here, in the brushless motor according to claim 3, the above-described detection unit responds to a change in the direction of leakage magnetic flux from the rotor magnet when the windings wound around the opposing teeth are in a non-energized state. It is arranged at a position where the polarity is switched.

  Therefore, when the output signal from the detection unit changes according to the switching of the polarity, no magnetic flux is generated from the winding wound around the teeth facing the detection unit, so the magnetic flux from the stator to the output signal The influence of can be reduced. Thereby, the detection accuracy of the rotational position of the rotor can be improved.

  In the brushless motor according to claim 3, when the plurality of windings constitute a U phase, a V phase, and a W phase, as described in claim 4, the detection unit The teeth are provided opposite to at least one of the motor radial direction and the motor axial direction, and the polarity changes according to the change in the direction of leakage magnetic flux from the rotor magnet when the U-phase winding is in a non-energized state. A U-phase detector disposed at such a position as to be switched; and the V-phase teeth and at least one of the motor radial direction and the motor shaft direction, and the V-phase winding is in a non-energized state. The V-phase detection unit disposed at a position where the polarity is switched in accordance with the change in the direction of the leakage magnetic flux from the rotor magnet, the W-phase teeth, the motor radial direction, and the motor axial direction The W phase is disposed opposite to the other and disposed at a position where the polarity is switched in accordance with a change in the direction of leakage magnetic flux from the rotor magnet when the W phase winding is in a non-energized state. It is preferable to have the detection unit.

  The brushless motor according to claim 5 is a configuration in which the brushless motor according to any one of claims 1 to 4 and the detection portion are disposed on the opposite side of the stator to the rotor magnet in the motor radial direction. It is said that.

  According to the brushless motor of the fifth aspect, the detection unit is disposed on the opposite side of the stator from the rotor magnet in the motor radial direction. Therefore, the influence of the magnetic flux from the stator on the detection unit can be further reduced, and the detection accuracy of the rotational position of the rotor can be further improved.

  A brushless motor according to a sixth aspect is the brushless motor according to the fifth aspect, wherein the rotor has a rotor yoke that holds the rotor magnet, and the rotor yoke includes the rotor magnet with respect to the detection unit in the motor radial direction. The opposite wall portion is formed on the opposite side so as to face the detection portion.

  According to the brushless motor of the sixth aspect, the rotor yoke has the opposing wall portion facing the detection portion on the side opposite to the rotor magnet with respect to the detection portion in the motor radial direction. Therefore, the leakage magnetic flux from the rotor magnet can be prevented from being released by the facing wall portion. Thereby, the detection accuracy of the rotational position of the rotor can be further improved.

  A brushless motor according to a seventh aspect is the brushless motor according to the sixth aspect, wherein the opposing wall portion is arranged so as to be shifted in the motor axial direction with respect to the stator.

  According to the brushless motor of the seventh aspect, the opposing wall portion is arranged so as to be shifted in the motor radial direction with respect to the stator. Therefore, the leakage magnetic flux from the rotor magnet can be detected more effectively by the detector while suppressing the flow of magnetic flux from the rotor magnet to the stator.

  The brushless motor according to claim 8 is the brushless motor according to any one of claims 1 to 7, wherein the detection unit induces a leakage magnetic flux from the rotor magnet, and the magnetic flux. The sensor has a sensor unit that outputs a signal corresponding to outputting a signal corresponding to the polarity while switching the polarity according to a change in the direction of the leakage magnetic flux induced by the induction unit.

  According to the brushless motor of the eighth aspect, since the detection unit is divided into the magnetic flux induction unit and the sensor unit, the degree of freedom of the arrangement of the sensor unit can be increased.

[First embodiment]
First, a first embodiment of the present invention will be described.

  FIG. 1 shows a brushless motor 10 according to a first embodiment of the present invention.

  As shown in this figure, the brushless motor 10 includes a stator 12, a rotor 14, a detection unit 16, and a control unit 18.

  The stator 12 includes a plurality of windings 22U1 to 22W2 constituting a U phase, a V phase, and a W phase, and teeth 24U1 to 24W2 around which the windings 22U1 to 22W2 are respectively wound.

  The rotor 14 includes a rotor magnet 26 that is disposed so as to face the stator 12 in the radial direction. The rotor magnet 26 includes N poles and S poles alternately in the rotation direction of the rotor 14. Yes.

  The detection unit 16 is provided to face, for example, the W-phase tooth 24W2 and at least one of the motor radial direction and the motor axial direction. The detection unit 16 includes, for example, a Hall element and the like, and the polarity is switched according to a change in the direction of leakage magnetic flux from the rotor magnet 26 and a signal corresponding to the polarity is output.

  The control unit 18 is configured by, for example, an electronic circuit, and detects the output signal from the detection unit 16 and detects the winding 22W2 in a non-energized state when the polarity of the detection unit 16 is switched. Based on the output signal from the part 16, it is set as the structure which switches the electricity supply state of several coil | winding 22U1-22W2.

  In other words, the detection unit 16 and the control unit 18 are configured as follows. That is, the detection unit 16 is arranged at a position where the polarity is switched according to the change in the direction of the leakage magnetic flux from the rotor magnet 26 when the winding 22W2 is in a non-energized state. The control unit 18 is configured to detect the output signal from the detection unit 16 and switch the energization states of the plurality of windings 22U1 to 22W2 based on the output signal.

  In the brushless motor 10, when the control unit 18 sequentially switches the energization states of the plurality of windings 22 U 1 to 22 W 2, the rotor 14 is rotated by receiving the rotating magnetic field from the stator 12. When the rotor 14 is rotated, a signal corresponding to the direction of the leakage magnetic flux from the rotor magnet 26 is output from the detection unit 16. Then, based on the output signal output from the detection unit 16, the control unit 18 switches the energization state of the plurality of windings 22U1 to 22W2, thereby rotating the rotor 14 at a predetermined rotational speed.

  Next, the operation and effect of the first embodiment of the present invention will be described.

  Here, in order to clarify the effect of the brushless motor 10 according to the first embodiment of the present invention, the brushless motor 10 according to the first embodiment of the present invention and the brushless motor 110 according to the comparative example are compared. To do.

  FIG. 7 shows a brushless motor 110 according to a comparative example. In this comparative example, the same reference numerals are used for the same configuration as in the first embodiment of the present invention.

  In the brushless motor 110 according to this comparative example, the detection unit 16 is provided to face the V-phase tooth 24V1 and at least one of the motor radial direction and the motor axial direction. The control unit 18 is configured to switch the energization states of the plurality of windings 22U1 to 22W2 based on the output signal from the detection unit 16 so that the winding 22V1 is energized when the polarity of the detection unit 16 is switched. It is said that.

  In other words, the detection unit 16 is arranged at a position where the polarity is switched according to a change in the direction of the leakage magnetic flux from the rotor magnet 26 when the winding 22V1 is energized. The control unit 18 is configured to detect the output signal from the detection unit 16 and switch the energization states of the plurality of windings 22U1 to 22W2 based on the output signal.

  However, in the brushless motor 110 according to this comparative example, when the detection unit 16 detects the leakage magnetic flux of the rotor magnet 26, the magnetic flux M from the stator 12 is superimposed on this leakage magnetic flux, and the rotational position of the rotor 14 is changed. There is a possibility that the detection accuracy is lowered.

  On the other hand, as shown in FIG. 1, in the brushless motor 10 according to the first embodiment of the present invention, the control unit 18 causes the winding 22W2 to be in a non-energized state when the polarity of the detection unit 16 is switched. In addition, the energization states of the plurality of windings 22U1 to 22W2 are switched based on the output signal from the detection unit 16. That is, in other words, the detection unit 16 is disposed at a position where the polarity is switched according to the change in the direction of the leakage magnetic flux from the rotor magnet 26 when the winding 22W2 is in a non-energized state.

  Therefore, when the output signal from the detection unit 16 changes in accordance with the switching of the polarity (for example, the signal level changes from one of LOW and HIGH to the other), since the magnetic flux is not generated from the winding 22W2, it is detected. The influence of the magnetic flux from the stator 12 on the output signal of the part 16 can be reduced. Thereby, the detection accuracy of the rotational position of the rotor 14 can be improved.

  Further, the arrangement position of the detection unit 16 is only changed from the conventional configuration (or the timing at which the polarity of the detection unit 16 is switched and the energization patterns of the plurality of windings 22U1 to 24W2 are changed from the conventional configuration. Therefore, it is not necessary to add a new member. Thereby, the detection accuracy of the rotational position of the rotor 14 can be improved while suppressing an increase in cost.

[Second Embodiment]
Next, a second embodiment of the present invention will be described.

  2A to 2F show a brushless motor 20 according to the second embodiment of the present invention. 3 shows the U-phase detector 16U, the V-phase detector 16V, the W-phase detector 16W, the terminal voltages of the U-phase windings 22U1 and 22U2, and the V-phase winding. The relationship between the terminal voltages of the lines 22V1 and 22V2 and the terminal voltages of the W-phase windings 22W1 and 22W2 is shown.

  The brushless motor 20 according to the second embodiment of the present invention has a so-called 10-pole 12-slot type in which the windings 22U1 to 22W2 are wound around the teeth 24U1 to 24W2 by concentrated winding and Y-connected to each other. The basic configuration of the brushless motor 10 according to the first embodiment of the present invention described above is the same.

  That is, each of the plurality of windings 22U1 to 22W2 includes four windings for each of the U phase, the V phase, and the W phase.

  Moreover, the detection parts 16U-16W are each provided one each. The detection unit 16U is provided to face the U-phase tooth 24U2 and at least one of the motor radial direction and the motor shaft direction, and the detection unit 16V includes at least the V-phase tooth 24V2, the motor radial direction and the motor shaft direction. It is provided facing one side. Similarly, the detection unit 16W is provided to face the W-phase tooth 24W2 and at least one of the motor radial direction and the motor shaft direction. Moreover, these detection parts 16U-16W are arrange | positioned every 60 degrees with a mechanical angle.

  In the present embodiment, the detection units 16U to 16W are arranged every 60 °, but may be arranged every 120 °.

  Moreover, in this brushless motor 10, while the output signal from detection part 16U-16W is detected by the control part 18 in the order shown by FIG. 2A-FIG. 2F, several winding 22U1-based on this each output signal. The energization state of 22W2 is switched (that is, the timing for switching the polarity of the detection units 16U to 16W and the energization pattern of the windings 22U1 to 22W2 are set as follows).

  That is, FIG. 2A shows the case of the electrical angle of 0 ° in FIG. In this case, the V-phase windings 22V1, 22V2 and the U-phase windings 22U1, 22U2 are energized so that current flows from the V-phase windings 22V1, 22V2 to the U-phase windings 22U1, 22U2. The W-phase windings 22W1 and 22W2 are in a non-energized state. At this time, in the detection unit 16W, the polarity is switched according to the change in the direction of the leakage magnetic flux from the rotor magnet 26, and a signal corresponding to the polarity is output from the detection unit 16W.

  FIG. 2B shows the case of the electrical angle of 60 ° in FIG. In this case, the W-phase windings 22W1, 22W2 and the U-phase windings 22U1, 22U2 are energized so that current flows from the W-phase windings 22W1, 22W2 to the U-phase windings 22U1, 22U2. The V-phase windings 22V1 and 22V2 are in a non-energized state. At this time, in the detection unit 16V, the polarity is switched according to the change in the direction of the leakage magnetic flux from the rotor magnet 26, and a signal corresponding to the polarity is output from the detection unit 16V.

  FIG. 2C shows the case of the electrical angle of 120 ° in FIG. In this case, the W-phase windings 22W1, 22W2 and the V-phase windings 22V1, 22V2 are energized so that current flows from the W-phase windings 22W1, 22W2 to the V-phase windings 22V1, 22V2. The U-phase windings 22U1 and 22U2 are in a non-energized state. At this time, in the detection unit 16U, the polarity is switched according to the change in the direction of the leakage magnetic flux from the rotor magnet 26, and a signal corresponding to the polarity is output from the detection unit 16U.

  FIG. 2D shows the case of the electrical angle of 180 ° in FIG. In this case, the U-phase windings 22U1, 22U2 and the V-phase windings 22V1, 22V2 are energized so that current flows from the U-phase windings 22U1, 22U2 to the V-phase windings 22V1, 22V2. The W-phase windings 22W1 and 22W2 are in a non-energized state. At this time, in the detection unit 16W, the polarity is switched according to the change in the direction of the leakage magnetic flux from the rotor magnet 26, and a signal corresponding to the polarity is output from the detection unit 16W.

  FIG. 2E shows the case of the electrical angle of 240 ° in FIG. In this case, the U-phase windings 22U1, 22U2 and the W-phase windings 22W1, 22W2 are energized so that current flows from the U-phase windings 22U1, 22U2 to the W-phase windings 22W1, 22W2. The V-phase windings 22V1 and 22V2 are in a non-energized state. At this time, in the detection unit 16V, the polarity is switched according to the change in the direction of the leakage magnetic flux from the rotor magnet 26, and a signal corresponding to the polarity is output from the detection unit 16V.

  FIG. 2F shows the case of the electrical angle of 300 ° in FIG. In this case, the V-phase windings 22V1, 22V2 and the W-phase windings 22W1, 22W2 are energized so that current flows from the V-phase windings 22V1, 22V2 to the W-phase windings 22W1, 22W2. The U-phase windings 22U1 and 22U2 are in a non-energized state. At this time, in the detection unit 16U, the polarity is switched according to the change in the direction of the leakage magnetic flux from the rotor magnet 26, and a signal corresponding to the polarity is output from the detection unit 16U.

  In this way, the control unit 18 makes the U-phase windings 22U1 and 22U2 non-energized when the polarity of the U-phase detection unit 16U switches, and the V-phase detection unit 16V switches when the polarity of the V-phase detection unit 16V switches. The energization states of the plurality of windings 22U1 to 22W2 are such that the windings 22V1 and 22V2 are in a non-energized state and the W-phase windings 22W1 and 22W2 are in a non-energized state when the polarity of the W-phase detection unit 16W is switched. Switch.

  Further, as shown in FIGS. 2C and 2F, the U-phase detection unit 16U responds to changes in the direction of the leakage magnetic flux from the rotor magnet 26 when the U-phase windings 22U1 and 22U2 are not energized. So that the polarity is switched. Further, as shown in FIGS. 2B and 2E, the V-phase detection unit 16V responds to changes in the direction of leakage magnetic flux from the rotor magnet 26 when the V-phase windings 22V1 and 22V2 are not energized. So that the polarity is switched. Further, as shown in FIGS. 2A and 2D, the W-phase detection unit 16 </ b> W responds to changes in the direction of leakage magnetic flux from the rotor magnet 26 when the W-phase windings 22 </ b> W <b> 1 and 22 </ b> W <b> 2 are not energized. So that the polarity is switched.

  Even if configured in this way, the influence of the magnetic flux from the stator 12 on the output signals of the detectors 16U to 16W can be reduced, thereby improving the detection accuracy of the rotational position of the rotor 14. it can.

  More preferably, as shown in FIG. 4, the control unit 18 advances the advance so that the phase of the terminal voltage of each of the windings 22U1 to 22W2 advances with respect to the phase of the output signal from the detection units 16U to 16W. Take control.

  With this configuration, when the detectors 16U, 16V, 16W output a signal corresponding to the direction of the leakage magnetic flux from the rotor magnet 26, the windings 22U2, corresponding to the detectors 16U, 16V, 16W. Since 22V2 and 22W2 are completely in a non-energized state, the detection accuracy of the rotational position of the rotor 14 can be further effectively improved.

  In the present embodiment, the brushless motor 10 has a so-called 10 poles and 12 slots, but may have other poles and slots.

[Third embodiment]
Next, a third embodiment of the present invention will be described.

  5 and 6 show a brushless motor 30 according to a third embodiment of the present invention.

  The brushless motor 30 according to the third embodiment of the present invention is configured as follows with respect to the brushless motor 10 according to the first embodiment of the present invention described above or the brushless motor 20 according to the second embodiment of the present invention described above. Has been changed.

  That is, the detection unit 16 includes a magnetic flux induction unit 32 that induces a leakage magnetic flux from the rotor magnet 26 and a sensor unit 34 that outputs a signal corresponding to the direction of the leakage magnetic flux induced by the magnetic flux induction unit 32. Yes.

  The magnetic flux guiding part 32 is made of, for example, an aluminum material and is fixed to the end plate 36. On the other hand, the sensor unit 34 is configured by, for example, a Hall element or the like that switches a polarity according to a change in the direction of the leakage magnetic flux induced by the magnetic flux guiding unit 32 and outputs a signal corresponding to the polarity. It is fixed.

  The detector 16 is arranged on the opposite side of the stator 12 with respect to the rotor magnet 26 in the motor radial direction (that is, on the outer side in the motor radial direction with respect to the rotor magnet 26 in this case).

  The rotor 14 also has a rotor yoke 40 that holds the rotor magnet 26. In the rotor yoke 40, an opposing wall portion 42 is formed opposite to the detection portion 16 on the side opposite to the rotor magnet 26 with respect to the detection portion 16 in the motor radial direction (that is, in this case, on the outside in the motor radial direction with respect to the detection portion 16). Has been. The opposing wall portion 42 is disposed so as to be shifted in the motor axial direction with respect to the stator 12.

  Next, the operation and effect of the third embodiment of the present invention will be described.

  Here, in order to clarify the effect of the brushless motor 30 according to the third embodiment of the present invention, the brushless motor 30 according to the third embodiment of the present invention and the brushless motor 130 according to the comparative example are compared. To do.

  8 and 9 show a brushless motor 130 according to a comparative example. In this comparative example, the same reference numerals are used for the same configuration as in the third embodiment of the present invention.

  The brushless motor 130 according to this comparative example has a detection unit 16 disposed between the rotor magnet 26 and the stator 12 in the motor radial direction with respect to the brushless motor 30 according to the third embodiment of the present invention described above. is there.

  Note that the brushless motor 130 according to this comparative example is detected by the control unit 18 so that the winding wound around the teeth facing the detection unit 16 is in a non-energized state when the polarity of the detection unit 16 is switched. The present invention is included in that the energization states of the plurality of windings are switched based on the output signal from the unit 16.

  In addition, the brushless motor 130 according to this comparative example has the detection unit 16 divided into the magnetic flux induction unit 32 and the sensor unit 34, so that the degree of freedom of arrangement of the sensor unit 34 can be increased. This is the same as the brushless motor 30 according to the third embodiment of the invention.

  However, in the brushless motor 130 according to this comparative example, the detection unit 16 is disposed between the rotor magnet 26 and the stator 12 in the motor radial direction. Therefore, when the polarity of the detection unit 16 is switched, the control unit 18 performs a plurality of operations based on the output signal from the detection unit 16 so that the winding wound around the teeth facing the detection unit 16 is in a non-energized state. Even when the energization state of the other winding is switched, when the detecting unit 16 detects the leakage magnetic flux of the rotor magnet 26, the magnetic flux from the other winding is superimposed on the leakage magnetic flux of the rotor magnet 26, and the rotor 14 There is a possibility that the detection accuracy of the rotational position is lowered.

  On the other hand, according to the brushless motor 30 according to the third embodiment of the present invention, the detection unit 16 is disposed on the side opposite to the stator 12 with respect to the rotor magnet 26 in the motor radial direction. Therefore, the influence of the magnetic flux from the stator 12 on the detection unit 16 can be further reduced, and the detection accuracy of the rotational position of the rotor 14 can be further improved.

  Moreover, according to the brushless motor 30 according to the third embodiment of the present invention, the rotor yoke 40 has the opposing wall portion 42 facing the detection portion 16 on the side opposite to the rotor magnet 26 with respect to the detection portion 16 in the motor radial direction. Is formed. Accordingly, it is possible to suppress the leakage magnetic flux from the rotor magnet 26 from being released to the outside in the motor radial direction by the facing wall portion 42. Thereby, the detection accuracy of the rotational position of the rotor 14 can be further improved.

  Further, according to the brushless motor 30 according to the third embodiment of the present invention, the opposing wall portion 42 is arranged so as to be shifted in the motor radial direction with respect to the stator 12. Therefore, the magnetic flux leakage from the rotor magnet 26 can be more effectively detected by the detection unit 16 while suppressing the flow of magnetic flux from the rotor magnet 26 to the stator 12 being prevented.

  In the third embodiment of the present invention, the brushless motor 30 is an outer rotor type, but may be an inner rotor type.

  As mentioned above, although one Embodiment of this invention was described, this invention is not limited above, Of course, it can change and implement variously within the range which does not deviate from the main point. .

It is a figure which shows the structure of the brushless motor which concerns on 1st embodiment of this invention. It is a figure which shows the case where the electrical angle is 0 degrees in the brushless motor which concerns on 2nd embodiment of this invention. It is a figure which shows the case where the electrical angle is 60 degrees in the brushless motor which concerns on 2nd embodiment of this invention. It is a figure which shows the case where the electrical angle is 120 degrees in the brushless motor which concerns on 2nd embodiment of this invention. It is a figure which shows the case where the electrical angle is 180 degrees in the brushless motor which concerns on 2nd embodiment of this invention. It is a figure which shows the case where the electrical angle is 240 degrees in the brushless motor which concerns on 2nd embodiment of this invention. It is a figure which shows the case where the electrical angle is 300 degrees in the brushless motor which concerns on 2nd embodiment of this invention. It is a figure which shows the relationship between the detection part and terminal voltage of a coil | winding in the brushless motor which concerns on 2nd embodiment of this invention. It is a figure which shows the relationship between the detection part and terminal voltage of a coil | winding in the brushless motor which concerns on 2nd embodiment of this invention. It is a side view including the partial cross section of the brushless motor which concerns on 3rd embodiment of this invention. It is a top view including the partial cross section (6-6 line cross section of FIG. 5) of the brushless motor which concerns on 3rd embodiment of this invention. It is a figure which shows the structure of the brushless motor which concerns on a comparative example. It is a side view including the partial cross section of the brushless motor which concerns on a comparative example. It is a top view including the partial cross section (9-9 line cross section of FIG. 8) of the brushless motor which concerns on a comparative example.

Explanation of symbols

10, 20, 30 ... brushless motor, 12 ... stator, 14 ... rotor, 16, 16U, 16V, 16W ... detection unit, 18 ... control unit, 22U1, 22U2, 22V1, 22V2 , 22W1, 22W2 ... Winding, 24U1, 24U2, 24V1, 24V2, 24W1, 24W2 ... Teeth, 26 ... Rotor magnet, 32 ... Magnetic flux induction part, 34 ... Sensor part, 36. ..End plate, 38 ... substrate, 40 ... rotor yoke, 42 ... opposite wall

Claims (8)

A stator having a plurality of windings and a plurality of teeth wound around each of the windings;
A rotor having a rotor magnet disposed radially opposite the stator;
One of the plurality of teeth is provided to face at least one of the motor radial direction and the motor axial direction, and the polarity is switched according to a change in the direction of leakage magnetic flux from the rotor magnet and the polarity is A detection unit that outputs a detected signal;
Based on the output signal, the output signal from the detection unit is detected, and the winding wound around the teeth facing the detection unit is turned off when the polarity of the detection unit is switched. A controller for switching the energization state of the plurality of windings;
Brushless motor with The plurality of windings constitute a U phase, a V phase, and a W phase,
The detection unit is provided to face at least one of the teeth and the motor radial direction and the motor axial direction in each phase of the U phase, V phase, and W phase,
The control unit is configured such that when the polarity of the U-phase detection unit is switched, the U-phase winding is de-energized, and when the polarity of the V-phase detection unit is switched, the V-phase winding is de-energized. Switching the energization state of the plurality of windings so that the W-phase winding is in a non-energized state when the polarity of the W-phase detection unit is switched.
The brushless motor according to claim 1. A stator having a plurality of windings and a plurality of teeth wound around each of the windings;
A rotor having a rotor magnet disposed radially opposite the stator;
The rotor is provided so as to face any one of the teeth and at least one of the motor radial direction and the motor shaft direction, and the rotor wound when the winding wound around the facing teeth is in a non-energized state. A detection unit that is arranged at a position where the polarity is switched according to a change in the direction of the leakage magnetic flux from the magnet, and outputs a signal according to the polarity;
A control unit that detects an output signal from the detection unit and switches the energization state of the plurality of windings based on the output signal;
Brushless motor with The plurality of windings constitute a U phase, a V phase, and a W phase,
The detector is
The U-phase teeth are provided facing at least one of the motor radial direction and the motor shaft direction, and the direction of the leakage magnetic flux from the rotor magnet changes when the U-phase winding is in a non-energized state. A U-phase detector disposed at a position where the polarity is switched in response,
The V-phase teeth are provided opposite to at least one of the motor radial direction and the motor axial direction, and change in the direction of leakage magnetic flux from the rotor magnet when the V-phase winding is in a non-energized state. A V-phase detection unit arranged at a position where the polarity is switched in response,
The W-phase teeth are provided opposite to at least one of the motor radial direction and the motor axial direction, and change in the direction of leakage magnetic flux from the rotor magnet when the W-phase winding is in a non-energized state. A W-phase detector arranged at a position where the polarity is switched in response,
Having
The brushless motor according to claim 3. The detector is disposed on the opposite side of the stator to the rotor magnet in the motor radial direction.
The brushless motor as described in any one of Claims 1-4. The rotor has a rotor yoke that holds the rotor magnet;
The rotor yoke has an opposing wall portion facing the detection portion on the opposite side of the rotor magnet with respect to the detection portion in the motor radial direction.
The brushless motor according to claim 5. The opposing wall portion is arranged to be shifted in the motor axial direction with respect to the stator.
The brushless motor according to claim 6. The detector is
A magnetic flux induction section for inducing leakage magnetic flux from the rotor magnet;
A sensor unit that switches the polarity according to a change in the direction of the leakage magnetic flux induced by the magnetic flux guiding unit and outputs a signal corresponding to the polarity;
Having
The brushless motor as described in any one of Claims 1-7.

Images