JP5085875B2 - Electric motor - Google Patents

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, the first and second rotors having permanent magnets are arranged concentrically, and the first rotor and the second rotor are rotated in the circumferential direction with respect to the other one of the first rotor and the second rotor. An electric motor that changes the relative phase between a rotor and a second rotor is known (see, for example, Patent Document 1).

In this electric motor, when the relative phases of both rotors are changed according to the rotational speed of the electric motor, the first rotor and the second rotor are moved by a member that is displaced along the radial direction by the action of centrifugal force. 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. By energizing and changing the rotating magnetic field speed, the relative positions in the circumferential direction of the first and second rotors are changed.
JP 2002-204541 A

  By the way, according to the electric motor of the above prior art, the characteristic (the ratio of induced voltage / rotation speed) of the electric motor can be made variable by changing the relative phase between the first rotor and the second rotor. On the other hand, however, there is a problem that the induced voltage waveform at the intermediate phase between the strong field phase and the weak field phase becomes asymmetrical and contains a lot of harmonic components. As a result, an increase in current loss caused by harmonics, a decrease in the rotational speed of the motor that reaches the withstand voltage of the inverter that controls the energization of the stator windings, and the inconvenience that it is difficult to control the energization of the motor. is there.

  Further, when the phase difference between the first and second rotors is controlled in accordance with the rotation speed of the electric motor, the first and second only in the operating state of the electric motor, that is, in the state where the centrifugal force according to the rotation speed is applied. The relative phase of the rotor can be changed, and the phase cannot be changed at an appropriate timing including the stop state of the electric motor. In addition, in this case, since the phase is changed regardless of the fluctuation of the power supply voltage at the power supply to the motor, there is a possibility that the magnitude relationship between the power supply voltage and the induced voltage of the motor is reversed, for example.

  The present invention has been made in view of the above circumstances, and not only can the characteristics be made variable, but also the phase between the strong field phase and the weak field phase among the relative phases in each rotor. It is an object of the present invention to provide an electric motor that can improve the operating efficiency by reducing the harmonic electromotive force of the motor and that can smoothly and reliably change the phase between the rotors.

In order to achieve such an object, the present invention comprises a first rotor and a second rotor in which a plurality of permanent magnets are arranged in the circumferential direction, concentrically around a rotation shaft, An electric motor comprising rotating means for rotating the second rotor in the circumferential direction to change the relative phase between the first rotor and the second rotor, and the shaft of the second rotor A third rotor that is arranged in parallel in a direction, and in which a plurality of permanent magnets are arranged in the circumferential direction and is rotatable coaxially with the second rotor, the rotating means rotates the second rotor At the same time, the third rotor is rotated in the opposite direction to the second rotor to change the relative phase between the first rotor and the third rotor.

  In the electric motor of the present invention, the phase of each rotor is changed by rotating the second rotor in the direction opposite to the second rotor at the same time as rotating the second rotor by the rotating means. . That is, for example, the permanent magnet of the first rotor and the permanent magnet of the second rotor are opposed to each other with magnetic poles of different polarities, and the permanent magnet of the first rotor and the permanent magnet of the third rotor are different. When the magnetic poles of the poles are opposed to each other, the amount of interlinkage magnetic flux by which the field magnetic flux by the permanent magnet of the first rotor is linked to the stator winding is the field magnetic flux by the permanent magnet of the second and third rotors. (Strengthened field phase). From this state, the rotating means rotates the second rotor and the third rotor in directions opposite to each other, so that the permanent magnet of the first rotor and the permanent magnet of the second rotor have the same polarity. The magnetic field flux by the permanent magnet of the first rotor is fixed by making the permanent magnets of the first rotor and the permanent magnet of the third rotor face each other with the same magnetic poles. The amount of interlinkage magnetic flux interlinking the child windings is weakened by the field magnetic flux generated by the permanent magnets of the second and third rotors (weakening field phase).

  Here, in the intermediate phase until the mutual phase between the rotors is changed from the strong field phase to the weak field phase, the permanent magnet and the third rotor of the second rotor that have rotated in opposite directions to each other. The permanent magnets are in parallel with magnetic poles of different polarities. At this time, when one of the plurality of permanent magnets of the first rotor is viewed, a part of the permanent magnets of different polarities adjacent to each other of the second rotor and a part of permanent magnets of the same polarity are used. Is opposed to the permanent magnet of the first rotor. On the other hand, at the same time, a part of the permanent magnets of the same polarity adjacent to each other in the third rotor and a part of the permanent magnets of the different polarity are opposed to the permanent magnets of the first rotor. In this way, the permanent magnet of the first rotor has a part of the permanent magnet having a different polarity and a part of the permanent magnet having the same polarity, which are alternately opposed to each other. The rapid change of is suppressed. As a result, the induced voltage waveform in the intermediate phase becomes symmetrical and the harmonic components are reduced. And, by reducing the harmonic components, it is possible to prevent current loss due to the harmonics, increase the number of revolutions of the electric motor that reaches the inverter withstand voltage, and further control the energization of the electric motor. Can be easy.

  In the present invention, the rotating means has a pair of ring gears that have an inner peripheral surface that engages with the spline corresponding to the outer peripheral surface of the rotating shaft, and that can be moved toward and away from each other along the axial direction of the rotating shaft. Gear contact / separation drive means for moving both ring gears in directions toward and away from each other along the axis of the shaft, and the second rotor and the third rotor are spline engagements corresponding to the outer peripheral surface of each ring gear. Both ring gears having inner peripheral surfaces to be joined to each other, and at least one of the outer peripheral surface of the rotating shaft and the outer peripheral surface of each ring gear is a helical spline. The second rotor and the third rotor are rotated in directions opposite to each other by contacting and separating each other.

  In the rotating means of the present invention, the inner peripheral surface of the second rotor is spline engaged with the outer peripheral surface of one ring gear, and the inner peripheral surface of the third rotor is spline engaged with the outer peripheral surface of the other ring gear. Further, the inner peripheral surfaces of the ring gears are spline-engaged with the outer peripheral surface of the rotating shaft in a state in which the ring gears can be moved toward and away from each other along the axial direction of the rotating shaft. Both ring gears are moved toward and away from each other along the axial direction of the rotating shaft by the gear contact / separation driving means. At this time, since at least one of the outer peripheral surface of the rotating shaft and the outer peripheral surface of each ring gear is a helical spline, the ring gears are in conflict with each other when the ring gear is driven by the gear contact / separation driving means. It moves along the axial direction of the rotating shaft while rotating in the direction. Thereby, even in the execution state of the synchronous operation of the first rotor, the second rotor, and the third rotor, or the stop state of the electric motor, the relative phase between the first rotor and the second rotor and The relative phase between the first rotor and the third rotor can be easily and appropriately changed.

  The gear contact / separation driving means includes a pressure chamber formed between the ring gears and a fluid passage formed on the rotating shaft and communicating with the pressure chamber, and fluid is supplied to the pressure chamber via the fluid passage. It is preferable that both ring gears are moved toward and away from each other by supplying them.

  According to this, since both ring gears can be expanded simply by supplying fluid to the pressure chamber via the fluid path, the relative phase between the first rotor and the second rotor can be simplified. And the relative phase of a 1st rotor and a 3rd rotor can be changed smoothly.

  An embodiment of the present invention will be described with reference to the drawings. 1 is a cross-sectional explanatory view showing a first rotor and a second rotor and a stator of an electric motor according to this embodiment, FIG. 2 is a cross-sectional explanatory view showing a schematic configuration of the electric motor according to this embodiment, and FIG. FIG. 3 (a) shows a state in which the permanent magnets of the first rotor and the permanent magnets of the second rotor are arranged with the same polarity in FIG. FIG. 3B is an explanatory diagram schematically illustrating the state in which the permanent magnets of the first rotor and the permanent magnets of the third rotor are arranged in the same polarity, and FIG. 4 is the present embodiment. FIG. 4 (a) schematically shows a state in which the permanent magnets of the first rotor and the permanent magnets of the second rotor are arranged opposite to each other. FIG. 4B is an explanatory diagram schematically showing a state in which the permanent magnets of the first rotor and the permanent magnets of the third rotor are arranged opposite to each other, FIG. FIG. 5A is an explanatory diagram schematically showing an intermediate phase state of the second rotor relative to the first rotor, and FIG. 5B is an intermediate phase state of each rotor of the electric motor according to the present embodiment. FIG. 6 is an explanatory diagram schematically showing an intermediate phase state of the third rotor relative to the first rotor, and FIG. 6 is a graph showing induced voltages in the strong field phase, the weak field phase, and the intermediate phase.

  As shown in FIG. 1, the electric motor 1 of the present embodiment includes an annular stator 2 and an annular first rotor 3 disposed inside the stator 2. An annular second rotor 4 disposed concentrically on the inner side, and concentrically disposed on the inner side of the first rotor 3 and disposed in parallel with the second rotor 4 in the same manner as the second rotor 4. And an annular third rotor 5. In FIG. 1, for convenience of explanation, a part of the second rotor 4 is cut away and a part of the third rotor 5 is exposed.

  As shown in FIG. 2, the first rotor 3 is supported on the outer periphery of a cylindrical support drum 7 connected to a substantially disk-shaped drive plate 6, and is attached to a hollow rotary shaft 8 via the drive plate 6. It is connected. The rotating shaft 8 is extrapolated to the output shaft 9, and the rotating shaft 8 and the output shaft 9 rotate integrally.

  Further, as shown in FIG. 1, the first rotor 3 is arranged in the circumferential direction of the substantially cylindrical first rotor core 10 and the first rotor core 10 at equal intervals, and is embedded and held in the first rotor core 10. The plurality of first permanent magnets 11 are provided. Each of the first permanent magnets 11 is formed in a plate shape whose radial direction is the thickness direction of the first rotor core 10 and is magnetized in the thickness direction. The first permanent magnets 11 adjacent to each other in the circumferential direction are arranged so that the magnetization directions are different from each other. That is, one first permanent magnet 11 is provided with an N pole on the outer peripheral side, and the other first permanent magnet 11 is provided with an S pole on the outer peripheral side, and a first permanent magnet with an N pole on the outer peripheral side. 11 and first permanent magnets 11 having S poles on the outer peripheral side are alternately arranged in the circumferential direction.

  As shown in FIG. 1, the second rotor 4 is arranged and arranged at equal intervals in the circumferential direction of the substantially cylindrical second rotor core 12 and the second rotor core 12, and is embedded and held in the second rotor core 12. A plurality of second permanent magnets 13 are provided. As with the first permanent magnet 11, the second permanent magnet 13 is formed in a plate shape with the radial direction of the second rotor core 12 as the thickness direction, and is magnetized in the thickness direction. One of the second permanent magnets 13 adjacent to each other is provided so that the outer peripheral side is an N pole, and the other second permanent magnet 13 is provided so that the outer peripheral side is an S pole, and the outer peripheral side is an N pole. The two permanent magnets 13 and the second permanent magnets 13 whose outer peripheral sides are S poles are alternately arranged in the circumferential direction.

  As shown in FIG. 2, the second rotor 4 has a width dimension along the axis of the rotation shaft 8 that is approximately ½ of the width dimension of the first rotor 3. It is included in the position of one half of the axial direction.

  The third rotor 5 has the same configuration as the second rotor 4, and is arranged at equal intervals in the circumferential direction of the substantially cylindrical third rotor core 14 and the third rotor core 14 as shown in FIG. And a plurality of third permanent magnets 15 embedded and held in the third rotor core 14. One of the third permanent magnets 15 adjacent to each other is provided with an N pole on the outer peripheral side, and the other third permanent magnet 15 is provided with an S pole on the outer peripheral side. The three permanent magnets 15 and the third permanent magnets 15 having S poles on the outer peripheral side are alternately arranged in the circumferential direction. Further, as shown in FIG. 2, the third rotor 5 has a width dimension along the axis of the rotation shaft 8 that is approximately ½ of the width dimension of the first rotor 3. It is enclosed in the other half part of the 1st rotor 3 adjacent to an axial direction.

Further, the second rotor 4 and the third rotor 5, as shown in FIG. 1, is connected to the rotating shaft 8 through the rotating means 16. As will be described in detail later, the rotation means 16 changes the relative phase between the first rotor 3 and the second rotor 4 by rotating the second rotor 4, and at the same time, the third rotor 3. The relative phase between the first rotor 3 and the third rotor 5 is changed by rotating the rotor 5 in the direction opposite to the second rotor 4.

  The stator 2 is formed in a substantially cylindrical shape facing the outer peripheral portion of the first rotor 3, and a rotating magnetic field that rotates the first rotor 3, the second rotor 4, and the third rotor 5. Is provided with a multi-phase stator winding 17.

  The electric motor 1 of the present embodiment constitutes a so-called brushless DC motor as described above, and is mounted as a drive source in a vehicle such as a hybrid vehicle or an electric vehicle. At this time, the stator 2 of the electric motor 1 is fixed to, for example, a housing (not shown) of a vehicle transmission, the output shaft 9 is connected to the input shaft of the transmission (not shown), and the driving force of the electric motor 1 causes the transmission to pass through the transmission. To the drive wheels (not shown) of the vehicle. When the 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 regenerative braking force and recovers the kinetic energy of the vehicle body as electric energy (regenerative energy). To do. Further, for example, in a hybrid vehicle, the output shaft 9 of the electric motor 1 is connected to a crankshaft of an internal combustion engine (not shown), and the electric motor 1 is used as a generator even when the output of the internal combustion engine is transmitted to the electric motor 1. Functions to generate power generation energy.

  Next, the rotation means 16 in the electric motor 1 of the present embodiment will be described. As shown in FIG. 2, the rotation means 16 is provided between the first ring gear 18 provided between the rotary shaft 8 and the second rotor 4, and between the rotary shaft 8 and the third rotor 5. And a second ring gear 19. The first ring gear 18 and the second ring gear 19 are movable toward and away from each other along the axis of the rotary shaft 8 (that is, can be selectively moved in directions close to and away from each other). Yes. Helical splines are formed on the outer peripheral surface of the rotating shaft 8, and helical splines corresponding to the helical splines of the rotating shaft 8 are formed on the inner peripheral surface of the first ring gear 18 and the inner peripheral surface of the second ring gear 19. ing. Thereby, the first ring gear 18 and the second ring gear 19 are spline-engaged with the rotary shaft 8.

  On the outer peripheral surface of the first ring gear 18 and the outer peripheral surface of the second ring gear 19, helical splines having a pitch opposite to that of the helical spline of the rotary shaft 8 are formed. A helical spline corresponding to the helical spline on the outer peripheral surface of the first ring gear 18 is formed on the inner peripheral surface of the second rotor 4, and the second rotor 4 and the first ring gear 18 are connected to each other by a spline. Are combined. Similarly, helical splines corresponding to the helical splines on the outer peripheral surface of the second ring gear 19 are formed on the inner peripheral surface of the third rotor 5, and the third rotor 5 and the second ring gear 19 are connected to each other by the spline. Are combined.

  A pressure chamber 20 is formed between the first ring gear 18 and the second ring gear 19. A communication port 21 (fluid path) communicating with the pressure chamber 20 is formed on the rotary shaft 8, and an oil supply path 22 formed on the output shaft 9 is connected to the communication port 21. A forced oil supply means (not shown) is connected to the oil supply path 22 so that oil can be pressurized and supplied into the pressure chamber 20 through the communication port 21. The pressure chamber 20, the communication port 21, the oil supply path 22, and the forced oil supply means constitute the gear contact / separation drive means of the present invention. Also, what is denoted by reference numeral 23 in FIG. 2 is an annular key that guides the second rotor 4 and third rotor 5 in the rotational direction while restricting movement in the axial direction, and is denoted by reference numeral 24. Is a thrust bearing for smoothly rotating the second rotor 4 and the third rotor 5.

  Next, the operation of the rotating means 16 having the above configuration will be described. First, as shown in FIG. 2, when the first ring gear 18 and the second ring gear 19 are close to each other (contact state), the first rotor 3, the second rotor 4, and the third rotor 5 Are rotated synchronously, and the relative phase between the first rotor 3, the second rotor 4, and the third rotor 5 is maintained unchanged. At this time, as shown in FIGS. 3A and 3B, the second permanent magnet 13 of the second rotor 4 and the third permanent magnet 15 of the third rotor 5 have the same magnetization direction. The second permanent magnet 13 and the third permanent magnet 15 and the first permanent magnet 11 of the first rotor 3 are opposed to each other with magnetic poles having different polarities. By arranging (ie, having the same polarity), a strong field state is obtained.

  On the other hand, when oil is pressurized and supplied into the pressure chamber 20, the first ring gear 18 and the second ring gear 19 are separated from each other along the rotation shaft 8, as indicated by phantom lines in FIG. 2. Since the rotating shaft 8 and the first ring gear 18 are engaged by a helical spline, the rotating shaft 8 rotates while moving along the rotating shaft 8. At the same time, the second ring gear 19 moves in the direction opposite to the first ring gear 18 along the rotation shaft 8. Thereby, the second ring gear 19 engaged with the same helical spline as the first ring gear 18 rotates in the opposite direction to the first ring gear 18 while moving.

  Further, as the first ring gear 18 rotates, the second rotor 4 engaged with the helical spline on the outer peripheral surface of the first ring gear 18 rotates, and at the same time, the second rotor 4 engages with the helical spline on the outer peripheral surface of the second ring gear 19. The combined third rotor 5 rotates in the opposite direction to the second rotor 4. At this time, the helical splines on the outer peripheral surface of the first ring gear 18 and the outer peripheral surface of the second ring gear 19 are at a reverse pitch with respect to the helical spline on the outer peripheral surface of the rotary shaft 8. Even if the moving distance when the two ring gears 19 are separated from each other along the rotation shaft 8 is relatively small, a sufficient amount of rotation between the third rotor 5 and the second rotor 4 can be obtained and quickly. It can be rotated.

  At this time, as shown in FIGS. 4A and 4B, the second permanent magnet 13 of the second rotor 4 and the third permanent magnet 15 of the third rotor 5 have the same magnetization. Are aligned in the axial direction, and the second permanent magnet 13 and the third permanent magnet 15 and the first permanent magnet 11 of the first rotor 3 are opposed to each other with the same polarity magnetic poles. The field-weakening state is obtained by entering the state (that is, the counter electrode arrangement).

  In the strong field state in which the permanent magnets 11, 13, and 15 shown in FIGS. 3 (a) and 3 (b) are arranged with the same polarity, as shown by the waveform a in FIG. Changes. On the other hand, in the field-weakening state in which the permanent magnets 11, 13, and 15 shown in FIGS. 4 (a) and 4 (b) are arranged as counter electrodes, the magnitude of the induced voltage is as shown by the waveform b in FIG. Change.

  Further, in the intermediate phase that is intermediate between the strong field state and the weak field state by the rotors 3, 4, 5, for example, the mutual phase between the rotors 3, 4, 5 is different from the strong field phase. In the intermediate phase during the change to the field weakening phase, as shown in FIG. 5A, the pair of second permanent magnets 13 that are adjacent to each other and have different polarities in the second rotor 4. Is opposed to the first permanent magnet 11 of the first rotor 3. On the other hand, as shown in FIG. 5 (b), a pair of third permanent magnets that are adjacent to each other and have opposite poles of the third rotor 5 that has been rotated in the opposite direction to the second rotor 4. A part of 15 faces the first permanent magnet 11 of the first rotor 3. As a result, the first permanent magnet 11 of the first rotor 3 includes a part of the second permanent magnet 13 of the second rotor 4 and the third permanent magnet of the third rotor 5 which are magnetic poles having different polarities. 15 and a part of the second permanent magnet 13 of the second rotor 4 and a part of the third permanent magnet 15 of the third rotor 5 which are magnetic poles of the same polarity are alternately opposed to each other. As a result, as shown in FIG. 6, the induced voltage waveform c in the intermediate phase becomes symmetrical with respect to the electrical angles 90 ° and 270 °. The induced voltage waveform d at the intermediate phase in the conventional motor shown for comparison in FIG. 5 is asymmetrical via the electrical angles 90 ° and 270 °, but the induced voltage at the intermediate phase of the electric motor 1 of the present embodiment. Since the waveform c is symmetrical, the harmonic component is reduced. And in the electric motor 1 of this embodiment, while reducing a harmonic component, the current loss resulting from a harmonic can be prevented, and the inverter (not shown) which controls the electricity supply to the stator coil | winding 17 can be prevented. ), The number of rotations of the electric motor 1 reaching the withstand voltage can be increased, and further, energization control to the electric motor 1 can be facilitated.

  In the rotation means 16 of the present embodiment, the spline engagement of the first ring gear 18 and the second ring gear 19 with the rotating shaft 8, the second rotor 4 with respect to the first ring gear 18 and the second ring gear 19, and Although the spline engagement of the third rotor 5 is both the engagement by the helical spline, the rotation of the second rotor 4 and the third rotor 5 due to the movement of the first ring gear 18 and the second ring gear 19 is reversed. If a sufficient amount of rotation is obtained, the spline engagement of the first ring gear 18 and the second ring gear 19 with the rotary shaft 8 and the second rotor 4 and the third ring with respect to the first ring gear 18 and the second ring gear 19 are achieved. Either one of the spline engagements of the rotor 5 may be a helical spline engagement, and the other may be a normal spline engagement that is movable only in the axial direction.

Cross-sectional explanatory drawing which shows the 1st rotor of the electric motor which concerns on one Embodiment of this invention, a 2nd rotor, and a stator. Cross-sectional explanatory drawing which shows schematic structure of the electric motor which concerns on this embodiment. Explanatory drawing which shows typically the strong field phase state of each rotor of the electric motor which concerns on this embodiment. Explanatory drawing which shows typically the field weakening phase state of each rotor of the electric motor which concerns on this embodiment. Explanatory drawing which shows typically the intermediate phase state of each rotor of the electric motor which concerns on this embodiment. The graph which shows the induced voltage in a strong field phase, a weak field phase, and its intermediate phase.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Electric motor, 3 ... 1st rotor, 4 ... 2nd rotor, 5 ... 3rd rotor, 8 ... Rotary shaft, 11 ... 1st permanent magnet, 13 ... 2nd permanent magnet, 15 ... 3rd permanent magnet , 16 ... rotating means, 18 ... first ring gear, 19 ... second ring gear, 20 ... pressure chamber, 21 ... communication port (fluid path).

Claims (3)

A first rotor and a second rotor having a plurality of permanent magnets arranged in the circumferential direction are provided concentrically around the rotation axis, and the second rotor is rotated in the circumferential direction with respect to the first rotor. An electric motor comprising rotating means for changing the relative phase between the first rotor and the second rotor,
A third rotor that is arranged in parallel in the axial direction of the second rotor, and in which a plurality of permanent magnets are arranged in the circumferential direction and rotatable coaxially with the second rotor;
The rotating means rotates the second rotor and simultaneously rotates the third rotor in a direction opposite to the second rotor, thereby causing a relative phase between the first rotor and the third rotor. An electric motor characterized by changing. The rotating means has an inner peripheral surface that engages with the spline corresponding to the outer peripheral surface of the rotating shaft, and a pair of ring gears that can be brought into and out of contact with each other along the axial direction of the rotating shaft, and along the axis of the rotating shaft. Gear contact / separation drive means for moving both ring gears in a direction to contact and separate each other,
The second rotor and the third rotor each have an inner peripheral surface that engages with the spline corresponding to the outer peripheral surface of each ring gear, and are respectively supported by the respective ring gears,
At least one of the outer peripheral surface of the rotating shaft and the outer peripheral surface of each ring gear is a helical spline, and the second rotor and the third rotor are reciprocal with each other due to the contact / separation of the ring gears by the gear contact / separation driving means. The electric motor according to claim 1, wherein the electric motor is rotated in the direction of rotation.   The gear contact / separation driving means includes a pressure chamber formed between the ring gears, and a fluid passage formed on the rotating shaft and communicating with the pressure chamber, and supplies fluid to the pressure chamber via the fluid passage. 3. The electric motor according to claim 2, wherein both ring gears are moved toward and away from each other.

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