JP2007282388A - Motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor capable of constantly increasing torque between both rotors when rotating either of the rotors in a circumferential direction to the other rotor, and facilitating the control of a phase angle between both the rotors when changing a relative phase of both the rotors with a rotating device. <P>SOLUTION: The pair of rotors 2, 3 having permanent magnets 4, 5 are concentrically provided around a rotating shaft 7. There is provided the rotating device 13 for rotating one rotor 3 to the other rotor 2 and changing the relative phase between both the rotors 2 and 3. Further, there is provided a forcing device 8 for forcing the one rotor 3 in a direction opposite to the phase change direction in a range in which the relative phase between both the rotors 2 and 3 becomes above a prescribed angle when one rotor 3 is rotated. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electric motor that includes a permanent magnet in a rotor and can change the field characteristics of the permanent magnet.

  Conventionally, an outer peripheral rotor including a permanent magnet and an inner peripheral rotor including a permanent magnet are concentrically arranged, and either the outer peripheral rotor or the inner peripheral rotor is arranged around the other. There is known an electric motor that changes the relative phase between an outer circumferential rotor and an inner circumferential rotor by rotating in a direction (see, for example, Patent Document 1).

  In this electric motor, when the relative phase of both rotors is changed according to the rotational speed of the electric motor, the outer rotor and the inner rotor are rotated by a member that is displaced along the radial direction by the action of centrifugal force. Either one of the children is rotated in the circumferential direction with respect to the other. In addition, when the relative phase of both rotors is changed according to the speed of the rotating magnetic field generated in the stator, a control current is applied to the stator winding in a state where each rotor maintains the rotation speed due to inertia. The relative position in the circumferential direction of the outer peripheral side rotor and the inner peripheral side rotor is changed by energizing and changing the rotating magnetic field speed.

And the characteristic (ratio of induced voltage / rotation speed) of an electric motor can be made variable by changing the relative phase of an outer peripheral side rotor and an inner peripheral side rotor. Specifically, when the permanent magnet of the outer rotor and the permanent magnet of the inner rotor face each other with different polarities (same polarity arrangement), the field is in a stronger state (stronger field phase). Thus, the induced voltage becomes large. On the other hand, when the permanent magnet of the outer rotor and the permanent magnet of the inner rotor face each other with the same polarity (counter electrode arrangement), the field becomes weakened (weak field phase). The induced voltage becomes small.
JP 2002-204541 A

  By the way, in this type of electric motor, if one of the rotors is rotated in the circumferential direction with respect to the other rotor, for example, when changing from a strong field phase to a weak field phase, Due to the interaction of the permanent magnets of the rotor, the torque between the two rotors once increases and then decreases when approaching the field weakening phase.

  For this reason, the relationship between the increase in the phase angle between the two rotors and the increase in the torque does not correspond, and even if an attempt is made to change the phase by controlling the rotation means such as the actuator, the phase angle indicating the same torque is Since there are two locations when the torque is increasing and when the torque is decreasing, there is an inconvenience that it is difficult to control the phase angle by a rotating means such as an actuator.

  The present invention has been made in view of the above circumstances, and when one of the rotors is rotated in the circumferential direction with respect to the other rotor, the torque between the two rotors can be increased constantly. An object of the present invention is to provide an electric motor that can easily control the phase angle between the two rotors when the relative phase of the two rotors is changed by the rotating means.

  In order to achieve such an object, the present invention includes a pair of rotors in which a plurality of permanent magnets having different polarities are alternately arranged along the circumferential direction, concentrically around a rotating shaft, and one rotor Is an electric motor provided with a rotating means for rotating the first rotor with respect to the other rotor to change the relative phase between the two rotors. Biasing means for urging the rotor in a direction opposite to the phase changing direction is provided in a range in which the relative phase between the rotors is a predetermined angle or more.

  According to the present invention, the relative phase between the two rotors is changed by rotating one rotor with respect to the other rotor by the rotating means. At this time, in the range where the relative phase between the two rotors is a predetermined angle or more, even if the torque between the two rotors decreases due to the interaction of the permanent magnets of the two rotors, The rotor is biased in the direction opposite to the phase change direction by the biasing means, whereby the torque between the rotors can be increased.

  Specifically, in the present invention, the phase between the two rotors is changed by the rotating means, and a first rotational torque is generated between the permanent magnet of one rotor and the permanent magnet of the other rotor. When generated, the urging means adds a second rotational torque due to the urging force to the first rotational torque that decreases within a range in which the relative phase between the two rotors is a predetermined angle or more. As a result, the torque can be increased constantly over the entire relative phase angle between the two rotors, and when the relative phase between the two rotors is changed by the rotating means, the phase angle between the two rotors Can be easily controlled.

  Here, the rotating means rotates one of the rotors so that the permanent magnet of one rotor faces the same pole from the state facing the opposite pole of the permanent magnet of the other rotor. . When the rotating means rotates one rotor from the state where the permanent magnets of both rotors face each other, the torque between the rotors gradually increases due to the interaction of the permanent magnets of both rotors. When the relative phase between the two rotors exceeds a predetermined angle, the torque between the two rotors gradually decreases. Therefore, in the range where the torque between the two rotors gradually decreases, the biasing force by the biasing means is surely applied, and the torque between the two rotors can be reliably increased. It is possible to accurately correspond to the phase angle.

  In the present invention, it is preferable that a frictional resistance applying means for providing a frictional resistance between the two rotors and maintaining a relative phase between the two rotors is provided. By applying frictional resistance between the two rotors by means of frictional resistance, it is possible to prevent the phase between the two rotors from becoming unstable due to external vibrations, etc. Can be done. In addition, after the relative phase between the two rotors is changed, one of the rotors is held at the changed phase angle by the rotating means. At this time, the phase is changed by the biasing means. One rotor is biased in the opposite direction to the direction. Therefore, the frictional resistance applying means applies a frictional resistance against the urging force of the urging means, and maintains the relative phase between the two rotors at a predetermined phase angle. And the relative phase between the two rotors can be reliably maintained at the changed phase.

  Embodiments of the present invention will be described with reference to the drawings. First, a first embodiment of the present invention will be described with reference to FIGS.

  As shown in FIG. 1, the electric motor 1 according to the first embodiment includes an annular outer circumferential rotor 2 and an inner circumferential rotor 3 disposed concentrically inside the outer circumferential rotor 2. I have. The outer peripheral rotor 2 includes a plurality of outer peripheral permanent magnets 4 along the circumferential direction. The inner circumferential rotor 3 includes a plurality of inner circumferential permanent magnets 5 arranged along the circumferential direction so as to face the outer circumferential permanent magnets 4 of the outer circumferential rotor 2. The inner circumferential side rotor 3 is provided so as to be rotatable in the circumferential direction with respect to the outer circumferential side rotor 2, and the relative phase with the outer circumferential side rotor 2 can be changed by this rotation. . A stator 6 having a plurality of phases of stator windings (not shown) for generating a rotating magnetic field for rotating the outer rotor 2 and the inner rotor 3 is provided on the outer periphery of the outer rotor 2. It has been.

  The electric motor 1 of the present embodiment is a brushless DC motor and is mounted as a drive source in a vehicle such as a hybrid vehicle or an electric vehicle, for example, and the rotating shaft 7 of the electric motor 1 is connected to an input shaft of a transmission (not shown). The driving force of the electric motor 1 is transmitted to driving wheels (not shown) of the vehicle via a transmission.

  When driving force is transmitted from the driving wheel side to the electric motor 1 during deceleration of the vehicle, the electric motor 1 functions as a generator to generate a so-called regenerative braking force, and the kinetic energy of the vehicle body is used as electric energy (regenerative energy). to recover. Further, for example, in a hybrid vehicle, the rotating shaft 7 of the electric motor 1 is connected to a crankshaft of an internal combustion engine (not shown), and the electric motor 1 is a generator even when the output of the internal combustion engine is transmitted to the electric motor 1. Function as a power generation energy.

  As shown in FIG. 1, the outer peripheral permanent magnet 4 provided on the outer rotor 2 is formed in a plate shape, and is magnetized in the thickness direction thereof (that is, the radial direction of the outer rotor 2). Yes. Further, the outer peripheral side permanent magnets 4 are arranged so that adjacent ones have different polarities (magnetization directions). That is, the outer peripheral side permanent magnets 4 whose outer peripheral side is an N pole and the outer peripheral side permanent magnets 4 whose outer peripheral side is an S pole are alternately arranged.

  Similarly, the inner peripheral side permanent magnet 5 provided in the inner peripheral side rotor 3 is formed in a plate shape and is magnetized in the thickness direction (that is, the radial direction of the inner peripheral side rotor 3). . The inner peripheral side permanent magnets 5 are arranged so that the adjacent ones have different polarities (magnetization directions). Specifically, the inner peripheral side permanent magnets 5 whose outer peripheral side is an N pole. And inner peripheral side permanent magnets 5 whose outer peripheral side is an S pole are alternately arranged.

  Further, as shown in part in FIGS. 1 and 2, an urging means 8 is provided between the rotating shaft 7 and the inner circumferential rotor 3. The biasing means 8 protrudes from the inner peripheral surface of the inner peripheral rotor 3 and the elastic member 10 which is a compression spring held on the rotary shaft 7 via the holding portion 9, and the inner peripheral rotor 3 rotates. Accordingly, a contact portion 11 that contacts the elastic member 10 is provided.

  As shown in FIG. 2, the outer circumferential rotor 2 is connected to the rotary shaft 7 via a drive plate 12. The inner circumferential rotor 3 is rotatably held by the rotary shaft 7 and is rotated around the rotary shaft 7 by an actuator 13 (rotating means).

  Next, the operation of the electric motor 1 of the first embodiment will be described with reference to FIGS. 3 and 4. FIG. 3A shows a strong field state in the electric motor 1. In this state, the outer peripheral side permanent magnet 4 of the outer peripheral side rotor 2 and the inner peripheral side permanent magnet 5 of the inner peripheral side rotor 3 are arranged so as to face each other with different polarities (same polarity arrangement). . In such a strong field state, the torque constant (torque / phase current) of the electric motor 1 can be set to a high value.

  Next, when the inner peripheral rotor 3 is rotated from the state shown in FIG. 3A, the inner peripheral rotor 3 is displaced with respect to the outer peripheral rotor 2 as shown in FIG. 3B. When the phase angle θ1 is reached, the contact portion 11 of the inner rotor 3 contacts the one end of the elastic member 10. When the inner circumferential rotor 3 is further rotated, the inner circumferential rotor 3 rotates while compressing the elastic member 10 by the contact portion 11 as shown in FIG. Then, the phase between the outer rotor 2 and the inner rotor 3 becomes the phase angle θ2, and the outer permanent magnet 4 of the outer rotor 2 and the inner permanent magnet 5 of the inner rotor 3. Are placed opposite to each other (counter electrode arrangement) to form a field-weakening state.

  Here, the relationship between the torque and the phase angle between the outer circumferential rotor 2 and the inner circumferential rotor 3 accompanying the rotation of the inner circumferential rotor 3 will be described with reference to FIG. The phase angle θ0 between the outer circumferential rotor 2 and the inner circumferential rotor 3 shown in a) is the phase angle θ1 between the outer circumferential rotor 2 and the inner circumferential rotor 3 shown in FIG. 4, the interaction between the outer peripheral side permanent magnet 4 and the inner peripheral side permanent magnet 5, which have been arranged with the same polarity, between the outer peripheral side rotor 2 and the inner peripheral side rotor 3 as shown in FIG. 4. The torque A due to the magnetic force increases. Subsequently, the phase angle θ1 between the outer circumferential rotor 2 and the inner circumferential rotor 3 shown in FIG. 3B is equal to the outer circumferential rotor 2 and the inner circumferential rotor 3 shown in FIG. 4 until the outer peripheral side permanent magnet 4 and the inner peripheral side permanent magnet 5 approach the counter electrode arrangement as shown in FIG. 4, until the phase angle θ2 between the outer peripheral side rotor 2 and the inner peripheral side rotor 3 is reached. Torque A due to the magnetic force between and decreases.

  On the other hand, in the present embodiment, as shown in FIG. 3B, the contact portion 11 of the inner rotor 3 contacts the one end of the elastic member 10 when the phase angle θ1 is reached, and FIG. The elastic member 10 is compressed by the contact portion 11 until the phase angle θ2 between the outer circumferential rotor 2 and the inner circumferential rotor 3 shown in FIG. As a result, the phase angle θ0 between the outer peripheral rotor 2 and the inner peripheral rotor 3 shown in FIG. 3A becomes equal to the outer peripheral rotor 2 and the inner peripheral rotor 3 shown in FIG. Until the phase angle θ1 is between, the contact portion 11 of the inner circumferential rotor 3 does not compress the elastic member 10 and torque B by the elastic member 10 does not occur, as shown in FIG. Subsequently, the phase angle θ1 between the outer circumferential rotor 2 and the inner circumferential rotor 3 shown in FIG. 3B is equal to the outer circumferential rotor 2 and the inner circumferential rotor 3 shown in FIG. Until the phase angle θ2 is between, the contact portion 11 of the inner circumferential rotor 3 compresses the elastic member 10 as shown in FIG. 4, so that the torque B by the elastic member 10 increases. Since the torque B (second rotational torque) by the elastic member 10 is added to the torque A (first rotational torque) due to the magnetic force between the phase angle θ1 and the phase angle θ2, the phase angle θ0 to the phase angle The total torque C up to θ2 increases approximately in proportion to the phase angle.

  In this way, by providing the biasing means 8, the phase angle and torque between the outer rotor 2 and the inner rotor 3 correspond to each other by a constant increase. The rotation control of the child 3 can be easily and accurately performed.

  Next, a second embodiment of the present invention will be described with reference to FIGS. As shown in FIG. 5, in the electric motor 14 of the second embodiment, an inner peripheral rotor 15 is connected to a rotary shaft 17 via a drive plate 16, and an outer peripheral rotor 18 is connected to a rotary shaft via an actuator 19. 17 and the inner circumferential rotor 15 are rotatably supported. Further, a biasing means 20 is provided between the outer peripheral side rotor 18 and the rotary shaft 17, and a frictional resistance applying means 21 is provided between the outer peripheral side rotor 18 and the inner peripheral side rotor 15. It has been. Similar to the first embodiment described above, the outer peripheral rotor 18 includes a plurality of outer peripheral permanent magnets 22, and the inner peripheral rotor 15 includes a plurality of inner peripheral permanent magnets 23.

  The urging means 20 in the electric motor 14 of the second embodiment includes an elastic member 25 that is a compression spring held on the rotating shaft 17 via a holding portion 24, and an outer periphery protruding from the inner peripheral surface of the outer rotor 18. A contact portion 26 that contacts the elastic member 25 as the side rotor 18 rotates is provided.

  The frictional resistance applying means 21 includes a friction disk 27 supported inside the outer rotor 18, a pressure plate 28 supported inside the inner rotor 15 and press-contactable with the friction disk 27, and The clutch is provided with a piston member 29 that is provided so as to be movable back and forth in the axial direction of the rotating shaft 17 and presses the pressure contact plate 28 against the friction disk 27. The piston member 29 forms a pressure chamber 30 between the piston plate 29 and the drive plate 16 of the inner circumferential rotor 15, and a communication hole 32 is connected to the pressure chamber 30 from an oil passage 31 formed inside the rotation shaft 17. The oil for pressurization is supplied through. As a result, the pressure chamber 30 is pressurized by the oil supplied through the oil passage 31, and the piston member 29 presses the pressure contact plate 28 against the friction disk 27 and frictionally engages the outer rotor 18. The phase with the inner rotor 15 is maintained at a desired phase. The piston member 29 is urged by a return spring 33 that urges the pressure plate 28 in a direction opposite to the pressing direction. When the pressure to the pressure chamber 30 is released, the friction disk 27 of the friction plate 27 is pressed by the pressure plate 28. The pressure contact is released, and the outer peripheral side rotor 18 can be rotated by the actuator 19 with respect to the inner peripheral side rotor 15.

  According to the electric motor 14 of the second embodiment, the outer peripheral side permanent magnet 22 of the outer peripheral side rotor 18 and the inner peripheral side permanent magnet 23 of the inner peripheral side rotor 15 are different in the state shown in FIG. The magnetic poles are arranged so as to face each other (same polarity arrangement), and a strong field state is obtained. Then, when the outer rotor 18 is rotated from this state, the outer rotor 18 is displaced with respect to the inner rotor 15 as shown in FIG. 6B, and the phase angle θ1 is obtained. Incidentally, the contact portion 26 of the outer rotor 18 contacts one end of the elastic member 25. Also in the electric motor 14 of the second embodiment, as in the first embodiment, the inner rotor 15 and the outer rotor 18 have a phase angle θ1 at which the torque due to the magnetic force starts to decrease. Sometimes, the contact portion 26 is set to start contact with the elastic member 25.

  When the outer circumferential rotor 18 is further rotated, the outer circumferential rotor 18 rotates while compressing the elastic member 25 by the contact portion 26 as shown in FIG. The phase between the inner circumferential rotor 15 and the outer circumferential rotor 18 becomes the phase angle θ2, and the inner and outer circumferential permanent magnets 23 of the inner circumferential rotor 15 and the outer circumferential permanent magnet 22 of the outer circumferential rotor 18 are obtained. Are placed opposite to each other (counter electrode arrangement) to form a field-weakening state. The phase angle θ1 between the outer peripheral side rotor 18 and the inner peripheral side rotor 15 shown in FIG. 6B is the same between the outer peripheral side rotor 18 and the inner peripheral side rotor 15 shown in FIG. Until the phase angle θ2 is reached, the contact portion 26 of the outer rotor 18 compresses the elastic member 25. Therefore, referring to FIG. 4, the torque B by the elastic member 25 increases and the total torque C is increased. Obtainable. Therefore, also in the electric motor 14 of the second embodiment, the torque with respect to the phase angle increases approximately proportionally, so that the rotation control of the outer peripheral rotor 18 by the actuator 19 can be easily and accurately performed.

  Further, in the electric motor 14 of the second embodiment, as shown in FIG. 5, by providing the frictional resistance applying means 21, for example, as shown in FIG. When the phase angle θ2 at which the torque between the outer circumferential rotor 18 and the inner circumferential rotor 15 is the highest, the piston member 29 is actuated to press the pressure contact plate 28 against the friction disk 27 and frictionally engage. Thus, the phase angle θ2 can be maintained. Thus, the phase angle θ2 at which the torque between the outer peripheral rotor 18 and the inner peripheral rotor 15 becomes the highest is maintained not only by the actuator 19 but also by the frictional engagement of the frictional resistance applying means 21. Therefore, the burden on the actuator 19 can be reduced.

  Next, a third embodiment of the present invention will be described with reference to FIG. As shown in FIG. 7, the electric motor 34 in the third embodiment includes an inner peripheral rotor 35 connected to a rotary shaft 37 via a drive plate 36, and an outer peripheral rotor 38 connected to a rotary shaft via an actuator 39. 37 and the inner circumferential rotor 35 are rotatably supported. Further, an urging means 40 and a frictional resistance applying means 41 are provided between the outer peripheral side rotor 38 and the inner peripheral side rotor 35.

  The urging means 40 includes an elastic member 43 that is a compression spring held via a holding portion 42 that is connected to the inner side of the outer peripheral rotor 38, and a drive plate 36 that is connected to the inner peripheral rotor 35. And an abutting portion 44 that abuts against the elastic member 43 as the outer circumferential rotor 38 rotates.

  The frictional resistance applying means 41 includes a friction disk 45 supported on the inner side of the outer circumferential rotor 38 and a pressure plate 46 supported on the inner side of the inner circumferential rotor 35 and freely press-contactable with the friction disk 45. And a disc spring member 47 supported inside the inner circumferential rotor 35 and brought into pressure contact with the friction disk 45 via the pressure contact plate 46.

  As a result, in the electric motor 34 in the third embodiment, the torque with respect to the phase angle is increased approximately proportionally by the urging means 40 as in the first and second embodiments. The rotation control of the outer circumferential rotor 38 can be easily and accurately performed.

  Further, the frictional resistance imparting means 41 in the electric motor 34 of the third embodiment always imparts a frictional resistance to the rotation of the outer peripheral rotor 38 relative to the inner peripheral rotor 35 by the disc spring member 47. As a result, for example, because it is mounted on a vehicle such as a hybrid vehicle or an electric vehicle, vibrations associated with road surface conditions and engine torque fluctuations are transmitted between the inner circumferential rotor 35 and the outer circumferential rotor 38. Even if such a situation occurs, the inadvertent movement of the outer circumferential rotor 38 relative to the inner circumferential rotor 35 is suppressed by the frictional resistance applying means 41, and between the inner circumferential rotor 35 and the outer circumferential rotor 38. The phase can be maintained in a stable state.

  The urging means 8, 20, and 40 in the first to third embodiments described above employ the elastic members 10, 25, and 43 that are compression springs, but are not limited thereto. For example, as shown in FIGS. 8A to 8C as a fourth embodiment of the present invention, a tension spring may be employed as the elastic member 48. That is, the electric motor 49 according to the fourth embodiment includes an annular outer circumferential rotor 50 and an inner ring disposed concentrically inside the outer circumferential rotor 50, as shown in part in FIG. A circumferential rotor 51 is provided. The outer circumferential rotor 50 includes a plurality of outer circumferential permanent magnets 52 along the circumferential direction, and the inner circumferential rotor 51 extends along the circumferential direction so as to face the outer circumferential permanent magnets 52 of the outer circumferential rotor 50. The inner peripheral rotor 51 is rotated by the actuator 39.

  A biasing means 55 is provided between the outer circumferential rotor 50 and the inner circumferential rotor 51. The biasing means 55 includes an elastic member 48 of a pulling spring having one end connected to the outer rotor 50 by a fixed pin 56 and the other end connected to the inner rotor 51 by a movable pin 57. The movable pin 56 is slidably held in a long hole-like holding groove 58 provided in the inner circumferential rotor 51.

  In the fourth embodiment, when the inner rotor 51 is rotated from the strong field state shown in FIG. 8A, the outer rotor 50 is moved with respect to the outer rotor 50 as shown in FIG. 8B. Although the inner rotor 51 is displaced, until the phase angle θ0 changes to the phase angle θ1, the movable pin 57 slides along the holding groove 58 and almost no urging force is generated by the elastic member 48.

  Then, as shown in FIG. 8B, the movable pin 57 is positioned at the end of the holding groove 58 when the phase angle θ1 is between the outer peripheral rotor 50 and the inner peripheral rotor 51, and slides. Is regulated. When the inner circumferential rotor 51 is further rotated from here, the inner circumferential rotor 51 rotates while stretching the elastic member 48 as shown in FIG. 8C. Then, the phase between the inner circumferential rotor 51 and the outer circumferential rotor 50 becomes the phase angle θ2, and the field weakening state is established.

  Thus, also in the electric motor 49 of the fourth embodiment, the torque A due to the magnetic force between the outer rotor 50 and the inner rotor 51 decreases between the phase angle θ1 and the phase angle θ2. In addition, the torque B with the elastic member 48 can be added to increase the torque with respect to the phase angle substantially proportionally.

Explanatory drawing which shows typically the principal part structure of the electric motor which concerns on the 1st Embodiment of this invention. Cross-sectional explanatory drawing of the principal part of the electric motor of 1st Embodiment. Operation | movement explanatory drawing of the electric motor of 1st Embodiment. The graph which shows the relationship between the phase angle and torque in the electric motor of 1st Embodiment. Cross-sectional explanatory drawing which shows typically the principal part of the electric motor which concerns on the 2nd Embodiment of this invention. Operation | movement explanatory drawing of the electric motor of 2nd Embodiment. Cross-sectional explanatory drawing which shows typically the principal part of the electric motor which concerns on the 3rd Embodiment of this invention. Explanatory drawing which shows typically the principal part structure and action | operation of the electric motor which concerns on the 4th Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1,14,34,49 ... Electric motor, 2,18,38,50 ... Outer peripheral side rotor (rotor), 3,15,35,51 ... Inner peripheral side rotor (rotor), 4,23,52 ... inner peripheral side permanent magnet (permanent magnet) 5, 22, 53 ... outer peripheral side permanent magnet (permanent magnet) 6, 17, 37 ... rotating shaft 8, 20, 40, 55 ... biasing means 13, 19 , 39 ... Actuators (turning means), 21, 41 ... Friction resistance applying means, A ... First rotational torque, B ... Second rotational torque.

Claims (4)

A pair of rotors in which a plurality of permanent magnets having different polarities are alternately arranged along the circumferential direction are provided concentrically around the rotation shaft, and one rotor is rotated with respect to the other rotor. An electric motor comprising rotating means for changing the relative phase between both rotors,
When one of the rotors is rotated by the rotating means, an urging means for urging the rotor in a direction opposite to the phase changing direction in a range where the relative phase between the two rotors is a predetermined angle or more. An electric motor is provided. When the phase between the two rotors is changed by the rotating means, and a first rotational torque is generated between the permanent magnet of one rotor and the permanent magnet of the other rotor,
The said urging means adds the 2nd rotational torque by urging | biasing force to the 1st rotational torque which reduces in the range from which the relative phase between both rotors becomes a predetermined angle or more. 1. The electric motor according to 1.   The rotating means rotates one rotor so that the permanent magnet of one rotor is opposed to the same pole from the state of facing the opposite pole of the permanent magnet of the other rotor. The electric motor according to claim 1 or 2.   4. The friction resistance applying means for applying a friction resistance between the two rotors to maintain a relative phase between the two rotors is provided. 5. Electric motor.

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