Patent Description:
In recent years, in connection with electrification of automobiles which can be seen in hybrid vehicles and electric vehicles, rotary electric machines which are capable of changing the magnetic force of a rotor have been developed. As such a rotary electric machine, <CIT> discloses a variable magnetic-force motor in which a permanent magnet with a small coercive force is incorporated into a rotor.

In the variable magnetic force motor disclosed in <CIT>, a plurality of magnetic pole parts are provided to the rotor. Each magnetic pole part includes a fixed magnetic-force magnet of which the magnetic force does not substantially change, and a variable magnetic-force magnet of which the magnetic force is changeable. As the fixed magnetic-force magnet, a first fixed magnetic-force magnet and a second fixed magnetic-force magnet are provided in a center part of the magnetic pole part in the circumferential direction. The first fixed magnetic-force magnet is disposed radially outward, and the second fixed magnetic-force magnet is disposed radially inward to form a V-shape. The variable magnetic-force magnet is disposed on both sides of the fixed magnetic-force magnet in the circumferential direction. The first fixed magnetic-force magnet is disposed at a position which becomes magnetically in series with the variable magnetic-force magnet, and the second fixed magnetic-force magnet is disposed at a position which becomes magnetically in parallel with the variable magnetic-force magnet.

A field magnetic flux which is generated from a stator is applied to the variable magnetic-force magnet. The magnetizing direction of the variable magnetic-force magnet is switched between two opposite sides in the circumferential direction according to the direction of the field magnetic flux applied. When the magnetizing direction of the variable magnetic-force magnet is oriented toward the fixed magnetic-force magnet, the magnet enters a magnetizing state where the amount of magnetic flux which is generated from the magnetic pole part increases. On the other hand, when the magnetizing direction of the variable magnetic-force magnet is oriented to the opposite side of the fixed magnetic-force magnet, the magnet enters a demagnetizing state where the amount of magnetic flux which is generated from the magnetic force part decreases.

According to the structure of the rotor disclosed in <CIT>, when switching the state to the magnetizing state from the demagnetizing state, or when strengthening the magnetic force of the variable magnetic-force magnet in the magnetizing state, magnetizing processing in which a field magnetic flux which is oriented in the magnetizing direction in the magnetizing state is applied to the variable magnetic-force magnet from the stator is performed. The field magnetic flux applied to the variable magnetic-force magnet by the magnetizing processing is generated by applying electric current to a coil wound around the stator core.

In order to suitably change the magnetic force of the variable magnetic-force magnet within restrictions of the electric current which can be applied to the stator coil, it is necessary in the magnetizing processing to collect the field magnetic flux to the variable magnetic-force magnet to increase the flux density of flux which passes through the variable magnetic-force magnet. On the other hand, in order to suppress the influence of the field magnetic flux related to a control of the magnetization state of the variable magnetic-force magnet on the magnetic force of the fixed magnetic-force magnet, it is preferred to dispose the fixed magnetic-force magnet radially inward of the variable magnetic-force magnet.

However, if the fixed magnetic-force magnet is disposed radially inward of the variable magnetic-force magnet, it is common to become magnetically in parallel like the relationship between the second fixed magnetic-force magnet and the variable magnetic-force magnet in <CIT>, and it is difficult to make the fixed magnetic-force magnet and the variable magnetic-force magnet form the magnetically in series relationship. With the absence of the magnetically in series relationship between the fixed magnetic-force magnet and the variable magnetic-force magnet, in the magnetizing processing, the high-density magnetic flux which is emitted from the variable magnetic-force magnet and the field magnetic flux for the magnetization which passes through the fixed magnetic-force magnet repel each other in the magnetic pole part where the fixed magnetic-force magnet is disposed so that the N-pole is oriented radially outward. Therefore, the flux density which passes through the variable magnetic-force magnet is reduced, and the magnetic force of the variable magnetic-force magnet cannot be changed suitably. A similar kind of motor has already been disclosed in <CIT>.

One purpose of the present disclosure is to increase a flux density of a magnetic flux which is applied to a variable magnetic-force magnet by magnetizing processing in a rotor in which a fixed magnetic-force magnet is disposed radially inward of the variable magnetic-force magnet.

A first aspect of the present disclosure relates to a rotor according to appended claim <NUM>. The rotor of the first aspect includes a rotor core, and a plurality of magnetic pole parts provided to the rotor core. The plurality of magnetic pole parts are lined up along an outer circumferential surface of the rotor core. The rotor is combined with a stator disposed radially outward of the rotor core, and a magnetic force of the plurality of magnetic pole parts is changeable by a given magnetic flux generated by the stator. Each magnetic pole part of the plurality of magnetic pole parts includes a fixed magnetic-force magnet which are disposed so that a magnetizing direction thereof is oriented in a radial direction of the rotor core, first variable magnetic-force magnets disposed at positions radially outward of the fixed magnetic-force magnet on both sides of the fixed magnetic-force magnet in a circumferential direction of the rotor core so that magnetizing directions thereof are oriented in the circumferential direction, and a magnetization state of the first variable magnetic-force magnets are changeable by the given magnetic flux, a first cavity part formed in the rotor core so as to extend between a position radially inward of the fixed magnetic-force magnet and a position radially inward of the first variable magnetic-force magnet, and a second cavity part formed in the rotor core so as to be separated radially outward from the first cavity part, the second cavity part extending toward the first variable magnetic-force magnet in the circumferential direction from a position radially outward of a surface on a first variable magnetic-force magnet side of the fixed magnetic-force magnet.

According to the first aspect, a magnetic flux path comprised of part of the rotor core is formed between the first cavity part and the second cavity part. Because of this flux path, the fixed magnetic-force magnet and the first variable magnetic-force magnet can form a magnetically in series relationship. Therefore, in magnetizing processing, it can be suppressed that high-density magnetic flux from the fixed magnetic-force magnet and the magnetization magnetic flux which passes through the first variable magnetic-force magnet repel each other, and thereby, the magnetization magnetic flux can be efficiently collected to the first variable magnetic-force magnet. Therefore, the flux density of the magnetic flux applied to the variable magnetic-force magnet can be increased by the magnetizing processing.

According to a second aspect of the present disclosure, in the rotor of the first aspect, a second variable magnetic-force magnet may be disposed between a part of the rotor core on the first variable magnetic-force magnet side of the second cavity part and the outer circumferential surface of the rotor core so that a magnetizing direction thereof is oriented in the circumferential direction. A magnetization state of the second variable magnetic-force magnet is changeable by the given magnetic flux.

According to the second aspect, the second variable magnetic-force magnet is disposed between the fixed magnetic-force magnet and the first variable magnetic-force magnet in the rotor core. Since the magnetizing direction of the second variable magnetic-force magnet is oriented in the circumferential direction similarly to the first variable magnetic-force magnet, the second variable magnetic-force magnet can form a magnetically in series relationship with the fixed magnetic-force magnet and the first variable magnetic-force magnet. Therefore, in the magnetizing processing, the magnetic flux related to a control of the magnetization state of the first variable magnetic-force magnet passes through the second variable magnetic-force magnet between the fixed magnetic-force magnet and the first variable magnetic-force magnet. This collects the magnetic flux to the first variable magnetic-force magnet further efficiently, which is advantageous to an increase in the flux density of the magnetic flux applied to the first variable magnetic-force magnet by the magnetizing processing.

According to a third aspect of the present disclosure, in the rotor of the first or second aspect, an auxiliary fixed magnetic-force magnet may be disposed between the fixed magnetic-force magnet of the rotor core and the outer circumferential surface of the rotor core so that a magnetizing direction thereof is oriented in the same direction as that of the fixed magnetic-force magnet. The second cavity part may extend so as to partition between the auxiliary fixed magnetic-force magnet and the first variable magnetic-force magnet.

According to the third aspect of the present disclosure, the auxiliary fixed magnetic-force magnet is disposed between the fixed magnetic-force magnet and the outer circumferential surface of the rotor core. Since the magnetizing direction of the auxiliary fixed magnetic-force magnet is oriented in the same direction as the fixed magnetic-force magnet, the auxiliary fixed magnetic-force magnet can form a magnetically in series relationship with the fixed magnetic-force magnet and the first variable magnetic-force magnet. Therefore, the magnetic force of the fixed magnetic-force magnet is reinforced by the auxiliary fixed magnetic-force magnet. Further, in the magnetizing processing, the magnetic flux related to a control of the magnetization state of the first variable magnetic-force magnet passes through the auxiliary fixed magnetic-force magnet between the fixed magnetic-force magnet and the stator. These are advantageous to a further efficient collection of the magnetic flux to the first variable magnetic-force magnet, and an increase in the flux density of the magnetic flux applied to the first variable magnetic-force magnet by the magnetizing processing.

A fourth aspect of the present disclosure relates to a rotary electric machine. The rotary machine of the fourth aspect includes the rotor of the first or second aspect, and a stator disposed radially outward of the rotor with an air gap therebetween.

A fifth aspect of the present disclosure relates to a vehicle. The vehicle of the fifth aspect includes the rotary electric machine of the fourth aspect, and driving wheels to which a motive force of the rotary electric machine is transmitted.

Hereinafter, an illustrative embodiment is described in detail based on the accompanying drawings. In the following embodiment, a rotor and a rotary electric machine according to the present disclosure will be described as an example where they are applied to a drive motor of an automobile. Note that terms such as "first," "second," and "third" are used in order to distinguish words and phrases to which these terms are given, and they are not intended to limit the number of the words and phrases, or their order.

An automobile <NUM> which is propelled by a drive motor is illustrated in <FIG>. The automobile <NUM> is a hybrid vehicle. The automobile <NUM> includes a drive source <NUM> and four wheels <NUM>.

As the drive source <NUM>, a drive motor (variable magnetic-force motor) <NUM> to which the art of the present disclosure is applied, and an engine 2E are mounted. The drive motor <NUM> is one example of a rotary electric machine. Two of the four wheels <NUM> are driving wheels 3D. The drive motor <NUM> and the engine 2E collaboratively rotate the two driving wheels 3D. Accordingly, the automobile <NUM> travels.

The automobile <NUM> of this example is a so-called "FR (front-engine, rear wheel drive) vehicle. " In this automobile <NUM>, the engine 2E is disposed at the front side of the vehicle body, and the driving wheels 3D are disposed at the rear side of the vehicle body. This automobile <NUM> adopts a so-called "mild hybrid system. " The engine 2E is mainly used as the drive source <NUM> of the automobile <NUM>. The drive motor <NUM> is used so as to assist the drive of the engine 2E. Further, the drive motor <NUM> is also used as a power generator during regeneration.

The engine 2E is an internal combustion engine which combusts using, for example, gasoline as fuel. The engine 2E may be a diesel engine which uses diesel oil as fuel. The drive motor <NUM> is a permanent magnet synchronous motor which drives by three-phase alternate current. Note that this drive motor <NUM> is a variable magnetic force motor as described above, which is changeable of a magnetic force of a rotor <NUM>. The device for improving the motor performance is given to the structure of the rotor <NUM> (the details will be described later).

The automobile <NUM> includes, in addition to the drive motor <NUM> and the engine 2E, a first clutch C1, an inverter <NUM>, a drive battery <NUM>, a second clutch C2, a transmission <NUM>, and a differential gear <NUM>, as devices of a drive system. The drive motor <NUM> is coupled to the rear side of the engine 2E via the first clutch C1. The drive battery <NUM> is connected to the drive motor <NUM> via the inverter <NUM>.

The drive battery <NUM> is comprised of a plurality of lithium-ion batteries. The rated voltage of the drive battery <NUM> is 50V or less (in detail, 48V). The drive battery <NUM> supplies direct current to the inverter <NUM>. The inverter <NUM> converts the direct current into three-phase alternate current having different phases, and supplies it to the drive motor <NUM>. Therefore, the drive motor <NUM> rotates.

The transmission <NUM> is coupled to the rear side of the drive motor <NUM> via the second clutch C2. The transmission <NUM> is a multi-stage automatic transmission (so-called "AT"). Rotational motive force outputted from one or both of the drive motor <NUM> and the engine 2E is outputted to the transmission <NUM> through the second clutch C2. The transmission <NUM> is coupled to the differential gear <NUM> via a propeller shaft.

The differential gear <NUM> is coupled to a pair of driving shafts <NUM>. The pair of driving shafts <NUM> are coupled to the left and right driving wheels 3D. When the automobile <NUM> travels (in powering), the rotational motive force which is changed in the speed by the transmission <NUM> is distributed by the differential gear <NUM>, and is then transmitted to the driving wheels 3D via the respective driving shafts <NUM>.

When the automobile <NUM> slows down (in regeneration), energy consumed by the drive motor <NUM> is recovered. In detail, when the automobile <NUM> brakes, the first clutch C1 is disengaged, while the second clutch C2 is engaged. Accordingly, the drive motor <NUM> is rotated by the rotational motive force of the driving wheels 3D to generate electricity, the generated power is charged to the drive battery <NUM> to collect the energy.

In the case of the hybrid vehicle described above, since the engine 2E is mainly used in powering, the influence of the drive motor <NUM> on the fuel efficiency is small. On the other hand, since the drive motor <NUM> is mainly used in regeneration, the influence of the drive motor <NUM> on the fuel efficiency is large.

The automobile <NUM> slows down highly frequently so that energy consumed during slowdown is large. Therefore, in order to improve the fuel efficiency of the hybrid vehicle, it is important to increase a rate of the energy recovery in regeneration. In order to increase the rate of the energy recovery in regeneration, increasing the output of the drive motor <NUM> is effective.

Regarding the increase in the output of the drive motor <NUM>, it is effective to enable a change in the magnetic force of the rotor <NUM> of the drive motor <NUM>. For this reason, the automobile <NUM> of this example adopts a variable magnetic force motor as the drive motor <NUM>. The variable magnetic force motor is capable of optimizing a power factor in a wide operating range.

In order to optimize the power factor, it is demanded that an electromagnetic force outputted from a stator <NUM> is substantially in coincidence with a magnetic force outputted from the rotor <NUM>. However, in the case of a normal permanent-magnet synchronous motor, the magnetic force of the rotor <NUM> is constant. Therefore, the optimization of the power factor is limited in a comparatively narrow operating range.

On the other hand, since the variable magnetic-force motor is able to change the magnetic force of the rotor <NUM>, it can optimize the power factor within the wide operating range. As a result, the output of the drive motor <NUM> can be increased. Further, since improvement in the efficiency and a reduction in the back electromotive force can also be realized, the energy efficiency of the automobile <NUM> (fuel efficiency, electricity efficiency) can be improved.

<FIG> illustrates a map where the operating range of the drive motor <NUM> is indicated. In this map, the operating range where the drive motor <NUM> is capable of outputting is defined by a load upper limit line Tm indicating an upper limit of torque (load) depending on the engine speed.

In detail, in a low-speed range up to a given engine speed r<NUM>, the upper limit of the torque is held at a maximum torque T<NUM>. In a middle-speed range and a high-speed range where the engine speed is higher than the low-speed range, the upper limit of the torque is gradually decreased until the engine speed reaches an upper limit r<NUM>. Such an operating range of the variable magnetic force motor is divided into a plurality of magnetizing ranges according to the magnetic force of the rotor <NUM> to optimize the power factor.

In the map illustrated in <FIG>, the magnetizing ranges are divided into a first magnetizing range Rm1, a second magnetizing range Rm2, and a third magnetizing range Rm3. The first magnetizing range Rm1 is a range which includes the maximum torque T<NUM> and extends on the higher-load side along the load upper limit line Tm. The second magnetizing range Rm2 is a range which extends on the lower-load side from the first magnetizing range Rm1. The third magnetizing range Rm3 is a range which extends on the lower-load side from the second magnetizing range Rm2, and includes a torque T<NUM> at which the drive motor <NUM> is idle (a torque which does not contribute to traveling of the automobile <NUM>).

In these three magnetizing ranges, optimal magnetic forces corresponding to the output are set to the rotor <NUM>, respectively. Normally, the magnetic force of the rotor <NUM> in the first magnetizing range Rm1 is set higher than the magnetic force of the rotor <NUM> in the second magnetizing range Rm2. Further, the magnetic force of the rotor <NUM> in the third magnetizing range Rm3 is set lower than the magnetic force of the rotor <NUM> in the second magnetizing range Rm2.

While the automobile <NUM> travels, the magnetizing range is estimated based on the operating state of the drive motor <NUM>. When moving from one magnetizing range to another, the magnetic force of the rotor <NUM> is changed according to the magnetic force of the destination magnetizing range. For example, when moving from the second magnetizing range Rm2 to the first magnetizing range Rm1, magnetizing processing is performed by the drive motor <NUM>. Further, when moving from the second magnetizing range Rm2 to the third magnetizing range Rm3, the demagnetizing processing is performed by the drive motor <NUM>.

In the magnetizing processing and the demagnetizing processing, a pulse-shaped d-axis current is applied to a given coil <NUM> at a timing when the rotor <NUM> is located at a given position with respect to the stator <NUM>. Accordingly, a strong magnetic field (magnetizing magnetic field) is generated by the stator for a variable magnetic-force magnet <NUM> which is a magnetizing target, and a magnetic flux according to the magnetic field is applied to the variable magnetic-force magnet <NUM>. Thus, the variable magnetic-force magnet <NUM> is magnetized until a given magnetic force is obtained. The direction of the magnetic field to be generated is opposite between the magnetizing processing and the demagnetizing processing.

In the magnetizing processing, the variable magnetic-force magnet <NUM> is magnetized so that the magnetic force is oriented in the same direction as a fixed magnetic-force magnet <NUM>, or so that the magnetic force which is oriented in the opposite direction from the fixed magnetic-force magnet <NUM> becomes weaker. In the demagnetizing processing, the variable magnetic-force magnet <NUM> is magnetized so that the magnetic force is oriented in the opposite direction from the fixed magnetic-force magnet <NUM>, or so that the magnetic force which is oriented in the same direction as the fixed magnetic-force magnet <NUM> becomes weaker. The direction of the magnetic force of the variable magnetic-force magnet <NUM> can be inverted, or the strength of the magnetic force can be changed depending on the magnetization state. In the following description, the increase in the magnetization of the variable magnetic-force magnet <NUM> by the magnetizing processing is referred to as "magnetization," and the decrease in the magnetization of the variable magnetic-force magnet <NUM> by the demagnetizing processing is referred to as "demagnetization.

Note that the magnetization of the variable magnetic-force magnet <NUM> by the magnetizing processing and the demagnetizing processing is limited by onboard apparatuses. That is, in order to magnetize the magnetic force of the variable magnetic-force magnet <NUM> strongly, it is necessary to supply large current to the drive motor <NUM>, and it is limited by the voltage of the drive battery <NUM> and the capacity of the inverter <NUM>.

Although increasing the sizes of these apparatuses may be considered, it is difficult to increase the sizes of the onboard apparatuses. Therefore, the disclosed art devises the structure of the drive motor <NUM> (especially, the structure of the rotor <NUM>) so that the magnetization can be appropriately performed even under the limited conditions using the existing apparatuses.

<FIG> illustrates a cross-sectional structure of the drive motor <NUM> seen in the axial direction. The drive motor <NUM> illustrated in <FIG> includes the stator <NUM>, the rotor <NUM>, and a shaft <NUM>. The drive motor <NUM> is a so-called "inner rotor type. " Note that in the following description, the axial direction indicates a direction along a rotation axis J of the rotor <NUM>. The radial direction indicates a direction perpendicular to the rotation axis J. The circumferential direction indicates a direction of the circumference centering on the rotation axis J.

The stator <NUM> is comprised of a cylindrical member, and is accommodated in a motor case (not illustrated) which is fixed to the vehicle body of the automobile <NUM>. The stator <NUM> includes a stator core <NUM> and a plurality of coils <NUM>. The stator core <NUM> is a so-called "laminated iron core," which is constituted by laminating in the axial direction a plurality of steel plates with high magnetic permeability. The coil <NUM> is constituted by winding electric wires around the stator core <NUM>.

In detail, the stator core <NUM> has a back yoke 11a and a plurality of teeth 11b. The back yoke 11a is formed annularly in the plan view, and constitutes an outer circumferential side part of the stator core <NUM>. The plurality of teeth 11b protrudes radially inward from the back yoke 11a at equal intervals. The stator <NUM> of this example has <NUM> teeth 11b. The coil <NUM> is constituted by winding an electric wire around a space (slot) formed between adjacent teeth 11b.

The plurality of coils <NUM> constitute a three-phase coil group which is comprised of U-phase, V-phase, and W-phase which differ in the phase of current flowing therethrough. The coils <NUM> of these phases are arranged in order in the circumferential direction. Each tooth 11b constitutes an electromagnet with the coil <NUM> of the corresponding phase. Electric current is applied to each coil <NUM> from the inverter <NUM>. When the current is applied to the coil <NUM>, a magnetic field is generated around the coil <NUM>.

The rotor <NUM> is comprised of a cylindrical member and is disposed inward of the stator <NUM>. An outer circumferential surface of the rotor <NUM> which is combined with the stator <NUM> opposes to an inner circumference surface of the stator <NUM> via a given air gap <NUM>. That is, the stator <NUM> is separated radially outward of the rotor <NUM> with the distance of air gap <NUM>. The rotor <NUM> includes a rotor core <NUM> and a plurality of magnetic pole parts <NUM>. In the rotor <NUM> of this example, the number of magnetic pole parts <NUM> is <NUM>.

The rotor core <NUM> is formed annularly in the plan view. The rotor core <NUM> is a so-called "laminated iron core," which is constituted by laminating in the axial direction a plurality of steel plates with high magnetic permeability. A shaft bore is formed in a center part of the rotor core <NUM>. The shaft <NUM> is inserted in the shaft bore. The shaft <NUM> is supported pivotally by a motor case. The rotor core <NUM> is fixed to the shaft <NUM> via a hub. Therefore, the rotor core <NUM> and the shaft <NUM> are integrally rotatable centering on the rotation axis J.

In the stator <NUM>, the magnetic field generated by the plurality of coils <NUM> includes a rotating magnetic field for rotating the rotor <NUM> and a magnetizing magnetic field for changing the magnetization state of the variable magnetic-force magnet <NUM>.

When driving current (alternate current) is supplied to the plurality of coils <NUM>, the rotating magnetic field is generated. The rotor <NUM> rotates by the interaction of the rotating magnetic field and the magnetic force of the rotor <NUM>. Further, when the pulse-shaped d-axis current is supplied to the plurality of coils <NUM> while the rotor <NUM> rotates (or stops), the magnetizing magnetic field is generated. The magnetization state of the variable magnetic-force magnet <NUM> is changed by the magnetizing magnetic field to magnetize or demagnetize the variable magnetic-force magnet <NUM>. As a result, the rotor <NUM> is configured so that the magnetic force of the magnetic pole part <NUM> is changeable.

Note that although in this embodiment the drive motor <NUM> with <NUM> poles and <NUM> slots is illustrated, the slot combination of the drive motor <NUM> is not limited to this combination. For example, the slot combination may be constituted so that the number of poles times 2N (x2N) and the number of slots times <NUM> (x3M) where N and M are integers. Especially, if the drive motor <NUM> is the type which is mounted on a vehicle, it is preferred to set the number of the poles within a range of <NUM> or more and <NUM> or less because of the limitation of the motor size, the demanded output, the structure of the rotor <NUM>, etc..

The plurality of magnetic pole parts <NUM> are provided to the rotor core <NUM>. The magnetic pole parts <NUM> are arranged so that they are lined up along an outer circumferential surface 32a of the rotor core <NUM>. Half (in this example, <NUM>) of the plurality of magnetic pole parts <NUM> are S-magnetic pole parts <NUM>, and the remaining half (in this example, <NUM>) are N-magnetic pole parts 33N. The S-magnetic pole part <NUM> is a magnetic pole part <NUM> of which the magnetic pole on the outer circumferential surface of the rotor <NUM> is an S-pole. The N-magnetic pole part 33N is a magnetic pole part <NUM> of which the magnetic pole on the outer circumferential surface of the rotor <NUM> is an N-pole.

The S-magnetic pole part <NUM> and the N-magnetic pole part 33N are provided so that they are lined up alternately in the circumferential direction. The S-magnetic pole part <NUM> and the N-magnetic pole part 33N have similar configurations except that their poles (in detail, magnetizing directions of the fixed magnetic-force magnet <NUM>, a first auxiliary fixed magnetic-force magnet <NUM>, and a second auxiliary fixed magnetic-force magnet <NUM>, which will be described later) on the outer circumferential surface 32a of the rotor core <NUM> and the positions in the circumferential direction differ. In the following description, when not distinguishing between the S-magnetic pole part <NUM> and the N-magnetic pole part 33N, each is simply referred to as the magnetic pole part <NUM>.

<FIG> illustrates a view where the S-magnetic pole part <NUM> of the rotor <NUM> of <FIG> is enlarged. Further, <FIG> illustrates a view where the N-magnetic pole part 33N of the rotor <NUM> of <FIG> is enlarged. In <FIG> and <FIG>, a line which extends radially from the rotation axis J and passes through the center of each magnetic pole part <NUM> in the circumferential direction indicates a d-axis (direct axis). Further, a line which extends radially from the rotation axis J and passes through the center between two adjacent magnetic pole parts <NUM> indicates a q-axis (quadrature axis).

Each magnetic pole part <NUM> includes the fixed magnetic-force magnet <NUM>, the first auxiliary fixed magnetic-force magnet <NUM>, the second auxiliary fixed magnetic-force magnet <NUM>, the variable magnetic-force magnet <NUM>, a nonmagnetic material <NUM>, and a cavity part. As the variable magnetic-force magnet <NUM>, a first variable magnetic-force magnet <NUM> and a second variable magnetic-force magnet <NUM> are provided. As the cavity part, a first cavity part <NUM>, a second cavity part <NUM>, and a third cavity part <NUM> are provided.

Solid-line arrows in <FIG> and <FIG> indicate magnetizing directions of the fixed magnetic-force magnet <NUM>, the first auxiliary fixed magnetic-force magnet <NUM>, and the second auxiliary fixed magnetic-force magnet <NUM>. Further, broken-line arrows in <FIG> and <FIG> indicate magnetizing direction of the first variable magnetic-force magnet <NUM> and the second variable magnetic-force magnet <NUM> in the magnetizing state.

The fixed magnetic-force magnet <NUM> is a magnetic element used as a main body of each magnetic pole part <NUM>, and plays a role in determining the polarity of the magnetic pole part <NUM> (S-magnetic pole part <NUM> or N-magnetic pole part 33N). The magnetic force of the fixed magnetic-force magnet <NUM> is the strongest. The fixed magnetic-force magnet <NUM> is formed in a rectangular shape in which long sides are sufficiently longer than the short side (for example, about <NUM> times longer). The fixed magnetic-force magnet <NUM> is located in a center part of the magnetic pole part <NUM> in the circumferential direction. The fixed magnetic-force magnet <NUM> is located comparatively inward within the magnetic pole part <NUM> in the radial direction. The fixed magnetic-force magnet <NUM> is disposed so that the magnetizing direction is oriented in the radial direction centering on the d-axis.

The fixed magnetic-force magnet <NUM> is provided so that a side surface on the long side is located along a direction perpendicular in the radial direction. Both the side surfaces of the long sides of the fixed magnetic-force magnet <NUM> constitute pole surfaces PF into/from which the magnetic flux enters/exits. Each pole surface PF of the fixed magnetic-force magnet <NUM> is perpendicular to the d-axis. The magnetizing direction of the fixed magnetic-force magnet <NUM> is inverted between the S-magnetic pole part <NUM> and the N-magnetic pole part 33N. In the fixed magnetic-force magnet <NUM> of the S-magnetic pole part <NUM>, the pole surface PF which faces radially outward is the S-pole, and the pole surface PF which faces radially inward is the N-pole. In the fixed magnetic-force magnet <NUM> of the N-magnetic pole part 33N, the pole surface PF which faces radially outward is the N-pole, and the pole surface PF which faces radially inward is the S-pole.

The fixed magnetic-force magnet <NUM> of this example is bisected at a position at which the d-axis passes. The fixed magnetic-force magnet <NUM> is comprised of a pair of magnet pieces 40a. The size of the pair of magnet pieces 40a (length and width) is mutually equivalent. The pair of magnet pieces 40a are located in line symmetry with respect to the d-axis. An inner coupling part <NUM> is provided in a middle part of the fixed magnetic-force magnet <NUM> in the rotor core <NUM>. The inner coupling part <NUM> extends in the radial direction between the pair of magnet pieces 40a, and couples a radially inward part and a radially outward part of the fixed magnetic-force magnet <NUM> of the rotor core <NUM>. The inner coupling part <NUM> extends on the d-axis.

The fixed magnetic-force magnet <NUM> is embedded in the rotor core <NUM>. A first accommodating hole Ha is formed at a disposed position of the fixed magnetic-force magnet <NUM> in the rotor core <NUM>. The first accommodating hole Ha is defined by the inner coupling part <NUM>. Each magnet piece 40a is accommodated in the first accommodating hole Ha. The first accommodating hole Ha may be designed so that a gap is formed as needed in a state where the fixed magnetic-force magnet <NUM> is accommodated. The magnet piece 40a is fixed to the rotor core <NUM> inside the first accommodating hole Ha. Adhesives are used for the fixation of the magnet piece 40a, for example.

The first auxiliary fixed magnetic-force magnet <NUM> is an auxiliary magnetic element of each magnetic pole part <NUM>, and has a function to reinforce the magnetic force of the fixed magnetic-force magnet <NUM>. The magnetic force of the first auxiliary fixed magnetic-force magnet <NUM> is the second strongest subsequently to the fixed magnetic-force magnet <NUM>. The first auxiliary fixed magnetic-force magnet <NUM> is formed in a rectangular shape in which both the short sides and the long sides are smaller than those of the fixed magnetic-force magnet <NUM>. The first auxiliary fixed magnetic-force magnet <NUM> is disposed between the fixed magnetic-force magnet <NUM> of the rotor core <NUM> and the outer circumferential surface 32a of this rotor core <NUM> so that the magnetizing direction is oriented in the radial direction centering on the d-axis.

The first auxiliary fixed magnetic-force magnet <NUM> is also provided so that the side surfaces on the long sides are oriented along a direction perpendicular in the radial direction. Both the side surfaces of the long sides of the first auxiliary fixed magnetic-force magnet <NUM> constitute pole surfaces PF. Each pole surface PF of the first auxiliary fixed magnetic-force magnet <NUM> is perpendicular to the d-axis. In each magnetic pole part <NUM>, the magnetizing direction of the first auxiliary fixed magnetic-force magnet <NUM> is oriented in the same direction as the magnetizing direction of the fixed magnetic-force magnet <NUM> to reinforce the magnetic force of the fixed magnetic-force magnet <NUM>. That is, the pole surfaces PF (S-pole and N-pole) of the first auxiliary fixed magnetic-force magnet <NUM> and the fixed magnetic-force magnet <NUM> which are lined up in the radial direction are oriented in the same direction.

The first auxiliary fixed magnetic-force magnet <NUM> is embedded in the rotor core <NUM>. A second accommodating hole Hb is formed at a disposed position of the first auxiliary fixed magnetic-force magnet <NUM> in the rotor core <NUM>. The first auxiliary fixed magnetic-force magnet <NUM> is accommodated in the second accommodating hole Hb. The second accommodating hole Hb may be designed so that a gap is formed as needed is in a state where the first auxiliary fixed magnetic-force magnet <NUM> is accommodated. The first auxiliary fixed magnetic-force magnet <NUM> is fixed to the rotor core <NUM> inside the second accommodating hole Hb. Adhesives are used for the fixation of the first auxiliary fixed magnetic-force magnet <NUM>, for example.

The second auxiliary fixed magnetic-force magnet <NUM> is an auxiliary magnetic element of each magnetic pole part <NUM>, and has a function to guide the magnetic flux of the fixed magnetic-force magnet <NUM>. Two second auxiliary fixed magnetic-force magnets <NUM> are provided to each magnetic pole part <NUM>. The second auxiliary fixed magnetic-force magnet <NUM> is formed in a rectangular shape of which the long side is slightly longer than the short side. The second auxiliary fixed magnetic-force magnets <NUM> are disposed on both sides of the fixed magnetic-force magnet <NUM> in the circumferential direction so that the magnetizing direction is oriented in the circumferential direction. The second auxiliary fixed magnetic-force magnet <NUM> is disposed in line symmetry with respect to the d-axis.

The second auxiliary fixed magnetic-force magnet <NUM> is provided so that the side surface on the long side is oriented in the radial direction. Both the side surfaces of the long side of the second auxiliary fixed magnetic-force magnet <NUM> constitute pole surfaces PF. The pole surface PF of the second auxiliary fixed magnetic-force magnet <NUM> is in a relationship parallel to the d-axis, and faces in the circumferential direction. The second auxiliary fixed magnetic-force magnet <NUM> is located adjacent to an end part of the fixed magnetic-force magnet <NUM> in the circumferential direction. One of the pole surfaces PF of the second auxiliary fixed magnetic-force magnet <NUM> is in contact with the fixed magnetic-force magnet <NUM>.

In the second auxiliary fixed magnetic-force magnet <NUM>, the pole surface PF which has the same polarity as the pole surface PF which faces radially outward of the fixed magnetic-force magnet <NUM> is located on the fixed magnetic-force magnet <NUM> side (that is, is oriented toward the fixed magnetic-force magnet <NUM>). In the second auxiliary fixed magnetic-force magnet <NUM> of the S-magnetic pole part <NUM>, the pole surface PF which faces on the fixed magnetic-force magnet <NUM> side is an S-pole, the pole surface PF on the opposite side is an N-pole, and the pole surface PF of the S-pole contacts the fixed magnetic-force magnet <NUM>. In the second auxiliary fixed magnetic-force magnet <NUM> of the N-magnetic pole part 33N, the pole surface PF which faces on the fixed magnetic-force magnet <NUM> side is an N-pole, the pole surface PF on the opposite side is an S-pole, and the pole surface PF of the N-pole contacts the fixed magnetic-force magnet <NUM>.

The second auxiliary fixed magnetic-force magnet <NUM> is embedded in the rotor core <NUM>. A third accommodating hole Hc is formed at a disposed position of the second auxiliary fixed magnetic-force magnet <NUM> in the rotor core <NUM>. The third accommodating hole Hc communicates with the second accommodating hole Hb. The second auxiliary fixed magnetic-force magnet <NUM> is accommodated in the third accommodating hole Hc. The third accommodating hole Hc may be designed so that a gap is formed as needed in a state where the second auxiliary fixed magnetic-force magnet <NUM> is accommodated. The second auxiliary fixed magnetic-force magnet <NUM> is fixed to the rotor core <NUM> inside the third accommodating hole Hc. Adhesives are used for the fixation of the second auxiliary fixed magnetic-force magnet <NUM>, for example.

The fixed magnetic-force magnet <NUM>, the first auxiliary fixed magnetic-force magnet <NUM>, and the second auxiliary fixed magnetic-force magnet <NUM> are similar to a conventional permanent magnet, which is a magnet in which a flux density of the magnetic material is substantially unchangeable (i.e., the magnetic force is constant and does not change). A magnet with high flux density and large coercive force is used for the fixed magnetic-force magnet <NUM>, the first auxiliary fixed magnetic-force magnet <NUM>, and the second auxiliary fixed magnetic-force magnet <NUM>. Such a magnet includes an Nd-Fe-B magnet, an Sm-Co magnet, an Fe-Ni magnet, and a ferrite magnet, for example.

The first variable magnetic-force magnet <NUM> and the second variable magnetic-force magnet <NUM> are magnetic elements which serve as the main body of each magnetic pole part <NUM> by collaborating with the fixed magnetic-force magnet <NUM>, and play a role to change the magnetic force of the magnetic pole part <NUM>. Each of the first variable magnetic-force magnet <NUM> and the second variable magnetic-force magnet <NUM> is capable of changing the magnetization state by the magnetic flux according to the magnetizing magnetic field (a given magnetic flux; hereinafter, referred to as a "magnetization magnetic flux"). The maximum total magnetic force of the first variable magnetic-force magnet <NUM> and the second variable magnetic-force magnet <NUM> is set to a magnetic force equivalent to or below the total magnetic force of the fixed magnetic-force magnet <NUM>, the first auxiliary fixed magnetic-force magnet <NUM>, and the second auxiliary fixed magnetic-force magnet <NUM>.

The first variable magnetic-force magnets <NUM> are disposed on both sides of the fixed magnetic-force magnet <NUM> in the circumferential direction. The first variable magnetic-force magnet <NUM> is disposed radially outward of the fixed magnetic-force magnet <NUM>. The first variable magnetic-force magnet <NUM> is disposed so that it covers over adjacent magnetic pole parts <NUM> and the magnetizing direction is oriented in the circumferential direction centering on the q-axis. The first variable magnetic-force magnets <NUM> are located at both ends of the magnetic pole part <NUM> in the circumferential direction, and are shared by adjacent magnetic pole parts <NUM> (the S-magnetic pole parts <NUM> and the N-magnetic pole parts 33N).

The first variable magnetic-force magnet <NUM> is constituted by two magnetic material pieces <NUM>. The magnetic material piece <NUM> is formed in a rectangular shape in which the long sides are sufficiently longer than the short sides (for example, about <NUM> times longer). The size (length and width) of the two magnetic material pieces <NUM> is mutually equivalent. The two magnetic material pieces <NUM> are disposed in line symmetry with respect to the q-axis, and each is adjacent to the q-axis. The length of the long side of the magnetic material piece <NUM> is substantially the same as the length of the short side of the fixed magnetic-force magnet <NUM>. The magnetic material piece <NUM> is disposed so that the side surfaces on the long sides is oriented in the radial direction.

The side surface of the long side of the magnetic material piece <NUM> constitutes a pole surface PF. The pole surface PF of the magnetic material piece <NUM> is in a relationship parallel to the q-axis, and faces in the circumferential direction. The two magnetic material pieces <NUM> are disposed next to each other in a state where their long sides are abutted to each other in the circumferential direction. The size of the first variable magnetic-force magnet <NUM> constituted in such a way is smaller than the size of the fixed magnetic-force magnet <NUM>. The coercive force of the first variable magnetic-force magnet <NUM> is smaller than the coercive forces of the fixed magnetic-force magnet <NUM>, the first auxiliary fixed magnetic-force magnet <NUM>, and the second auxiliary fixed magnetic-force magnet <NUM>.

The first variable magnetic-force magnet <NUM> is embedded in the rotor core <NUM>. A fourth accommodating hole Hd is formed at a disposed position of the first variable magnetic-force magnet <NUM> in the rotor core <NUM>. The first variable magnetic-force magnet <NUM> is accommodated in the fourth accommodating hole Hd. The first variable magnetic-force magnet <NUM> is fixed to the rotor core <NUM> inside the fourth accommodating hole Hd. Adhesives are used for the fixation of the first variable magnetic-force magnet <NUM>, for example.

The fourth accommodating hole Hd is opened at the outer circumferential side of the rotor core <NUM>. An overhang piece 32b which overhangs inwardly of its opening is provided on both sides in the circumferential direction in the open end of the fourth accommodating hole Hd. The overhang piece 32b functions as a lock which prevents withdrawal of the first variable magnetic-force magnet <NUM>. The first variable magnetic-force magnet <NUM> is exposed on the outer circumference side of the rotor core <NUM> from the open end (between the overhang pieces 32b) of the fourth accommodating hole Hd (i.e., the stator <NUM> side).

Two second variable magnetic-force magnets <NUM> are provided to each magnetic pole part <NUM>. The second variable magnetic-force magnet <NUM> is disposed between the fixed magnetic-force magnet <NUM> and each first variable magnetic-force magnet <NUM> in the circumferential direction. The second variable magnetic-force magnet <NUM> is disposed radially outward of the fixed magnetic-force magnet <NUM>. In detail, the second variable magnetic-force magnet <NUM> is disposed at a position closer to the first variable magnetic-force magnet <NUM>, between the first auxiliary fixed magnetic-force magnet <NUM> and the first variable magnetic-force magnet <NUM>.

The second variable magnetic-force magnet <NUM> is disposed in line symmetry with respect to the d-axis. The second variable magnetic-force magnet <NUM> is disposed so that it is lined up in parallel with the first variable magnetic-force magnet <NUM> in the circumferential direction with a gap therebetween and the magnetizing direction is oriented in the circumferential direction. The second variable magnetic-force magnet <NUM> is set magnetically in series with the first variable magnetic-force magnet <NUM> during the magnetizing processing. The second variable magnetic-force magnet <NUM> is constituted by one magnetic material piece <NUM> which is the same as that of the first variable magnetic-force magnet <NUM>.

The magnetic material piece <NUM> is disposed so that the side surface on the long side which forms the pole surface PF is oriented along the radial direction. The pole surface PF of the magnetic material piece <NUM> is in a relationship parallel to the q-axis, and faces in the circumferential direction. The size of the second variable magnetic-force magnet <NUM> is sufficiently smaller than the size of the fixed magnetic-force magnet <NUM>. The coercive force of the second variable magnetic-force magnet <NUM> is weaker than the coercive forces of the fixed magnetic-force magnet <NUM>, the first auxiliary fixed magnetic-force magnet <NUM>, and the second auxiliary fixed magnetic-force magnet <NUM>.

The second variable magnetic-force magnet <NUM> is embedded in the rotor core <NUM>. A fifth accommodating hole He is formed at a disposed position of the second variable magnetic-force magnet <NUM> in the rotor core <NUM>. The second variable magnetic-force magnet <NUM> is accommodated in the fifth accommodating hole He. The fifth accommodating hole He may be designed so that a gap is formed as needed in a state where the second variable magnetic-force magnet <NUM> is accommodated. The second variable magnetic-force magnet <NUM> is fixed to the rotor core <NUM> inside the fifth accommodating hole He. Adhesives are used for the fixation of the second variable magnetic-force magnet <NUM>, for example.

Each of the first variable magnetic-force magnet <NUM> and the second variable magnetic-force magnet <NUM> is a magnet in which the magnetic flux density is variable (i.e., the magnetic force is changeable). A magnet with high flux density but small coercive force is used for the first variable magnetic-force magnet <NUM> and the second variable magnetic-force magnet <NUM>. Such a magnet includes an Nd-Fe-B magnet, an Sm-Co magnet, an Fe-Ni magnet, and an Al-Ni-Co magnet, for example.

The magnetization states of the first variable magnetic-force magnet <NUM> and the second variable magnetic-force magnet <NUM> are easier to change than the magnetization states of the fixed magnetic-force magnet <NUM>, the first auxiliary fixed magnetic-force magnet <NUM>, and the second auxiliary fixed magnetic-force magnet <NUM>. Although the magnetization states of the fixed magnetic-force magnet <NUM>, the first auxiliary fixed magnetic-force magnet <NUM>, and the second auxiliary fixed magnetic-force magnet <NUM> do not substantially change with the large current which is outputtable from the drive battery <NUM> and the inverter <NUM> (for example, <NUM> Arms), this current can change the magnetization states of the first variable magnetic-force magnet <NUM> and the second variable magnetic-force magnet <NUM>. Therefore, the magnetic forces of the first variable magnetic-force magnet <NUM> and the second variable magnetic-force magnet <NUM> are changeable. Note that the current when driving the drive motor <NUM> also hardly changes the magnetization states of the first variable magnetic-force magnet <NUM> and the second variable magnetic-force magnet <NUM>. Therefore, for the normal drive, the first variable magnetic-force magnet <NUM> and the second variable magnetic-force magnet <NUM> also function as permanent magnets.

The nonmagnetic material <NUM> is disposed radially inward of the first variable magnetic-force magnet <NUM>. The nonmagnetic material <NUM> is formed in a rectangular shape in which the long side is sufficiently longer than the short side (for example, about <NUM> times longer). The nonmagnetic material <NUM> is disposed so that the side surface of the short side is perpendicular to the q-axis centering on the q-axis. The length of the short side of the nonmagnetic material <NUM> is longer than the length of the short side of the first variable magnetic-force magnet <NUM>. The nonmagnetic material <NUM> is located radially inward of the full width in the circumferential direction of the first variable magnetic-force magnet <NUM>. The nonmagnetic material <NUM> is made of synthetic resin, for example.

The nonmagnetic material <NUM> is embedded in the rotor core <NUM>. A sixth accommodating hole Hf is formed at the disposed position of the nonmagnetic material <NUM> in the rotor core <NUM>. The nonmagnetic material <NUM> is accommodated in the sixth accommodating hole Hf. The sixth accommodating hole Hf may communicate with the fifth accommodating hole He. The sixth accommodating hole Hf may be designed so that a gap is formed as needed in a state where the nonmagnetic material <NUM> is accommodated. The nonmagnetic material <NUM> is fixed to the rotor core <NUM> inside the sixth accommodating hole Hf. Adhesives are used for the fixation of the nonmagnetic material <NUM>, for example.

Two first cavity parts <NUM> are formed at each magnetic pole part <NUM>. The two first cavity parts <NUM> are disposed in line symmetry with respect to the d-axis. The first cavity part <NUM> has a larger aperture area than the second cavity part <NUM> and the third cavity part <NUM>. The first cavity part <NUM> is formed in the rotor core <NUM> so that it extends between a position radially inward of to the fixed magnetic-force magnet <NUM> and a position radially inward of the first variable magnetic-force magnet <NUM>. The first cavity part <NUM> is formed so that it corresponds partly in the radial direction to the fixed magnetic-force magnet <NUM> and the second auxiliary fixed magnetic-force magnet <NUM>.

In detail, the first cavity part <NUM> extends from a position radially inward of the magnet piece 40a which forms the fixed magnetic-force magnet <NUM> to a position near the nonmagnetic material <NUM> in the circumferential direction. The first cavity part <NUM> extends progressively more radially outward from a fixed magnetic-force magnet <NUM> side thereof toward a nonmagnetic material <NUM> side thereof. A radially outward part of the first cavity part <NUM> is located between the second auxiliary fixed magnetic-force magnet <NUM> and the nonmagnetic material <NUM>, immediately radially inward of an area between the first variable magnetic-force magnet <NUM> and the second variable magnetic-force magnet <NUM>.

A first pillar part <NUM> is formed in the rotor core <NUM>, between the first cavity parts <NUM> which are adjacent to each other on both sides of the q-axis. The first pillar part <NUM> includes the nonmagnetic material <NUM>. The width of the first pillar part <NUM> in the circumferential direction is slightly wider than the width of the nonmagnetic material <NUM> in the circumferential direction. Wall parts 35a between the first cavity parts <NUM> on both sides of the nonmagnetic material <NUM> in the first pillar part <NUM> are comparatively thin, and, for example, they are the thinnest in the rotor core <NUM>.

The third cavity part <NUM> is formed between two first cavity parts <NUM> at each magnetic pole part <NUM>. The third cavity part <NUM> is formed substantially in a rectangular shape centering on the d-axis. A second pillar part <NUM> is formed between each first cavity part <NUM> and the third cavity part <NUM> in the rotor core <NUM>. The second pillar part <NUM> is disposed in line symmetry with respect to the d-axis. The second pillar part <NUM> is located on the d-axis side with respect to the full width of the fixed magnetic-force magnet <NUM>.

The radially outside of the first cavity part <NUM> is defined by a curved surface 61a which extends from a radially outward end part of the first pillar part <NUM> to a radially outward end part of the second pillar part <NUM>. The curved surface 61a is located near the fixed magnetic-force magnet <NUM> and the second auxiliary fixed magnetic-force magnet <NUM>, and extends along the fixed magnetic-force magnet <NUM> and the second auxiliary fixed magnetic-force magnet <NUM>. The curved surface 61a has an arc shape which bulges radially inward, when seen in the axial direction.

Two second cavity parts <NUM> are formed at each magnetic pole part <NUM>. The two second cavity parts <NUM> are also disposed in line symmetry with respect to the d-axis. The second cavity part <NUM> is separated radially outward of the first cavity part <NUM>, and is located between the first auxiliary fixed magnetic-force magnet <NUM> and the first variable magnetic-force magnet <NUM> in the circumferential direction. The second cavity part <NUM> is formed in the rotor core <NUM> so that it extends toward the first variable magnetic-force magnet <NUM>, from a position radially outward of a surface of the fixed magnetic-force magnet <NUM> on the first variable magnetic-force magnet <NUM> side (e.g., an end surface 40b), in the circumferential direction.

In detail, the second cavity part <NUM> is formed substantially in an L-shape. The second cavity part <NUM> has a radial-side extending part 62a and a circumferential-side extending part 62b. The radial-side extending part 62a extends radially outwardly from a radially outward side of the second auxiliary fixed magnetic-force magnet <NUM> so that it partitions between the first auxiliary fixed magnetic-force magnet <NUM> and the first variable magnetic-force magnet <NUM>. The circumferential-side extending part 62b extends from a position radially outward of the second auxiliary fixed magnetic-force magnet <NUM> to a position radially inward of the second variable magnetic-force magnet <NUM>.

The width of the radial-side extending part 62a in the circumferential direction becomes narrower in a radially outward direction from the fixed magnetic-force magnet <NUM> up to a position in the middle of the radial-side extending part 62a, and it is substantially constant from the position in the middle of the radial-side extending part 62a up to a radially outward end part. The width of the circumferential-side extending part 62b in the radial direction becomes narrower as it approaches the first variable magnetic-force magnet <NUM> in the circumferential direction. The minimum width of the circumferential-side extending part 62b in the radial direction is equivalent to the minimum width of the radial-side extending part 62a in the circumferential direction, or wider than the minimum width of the radial-side extending part 62a in the circumferential direction.

A side surface of the radial-side extending part 62a on the d-axis side extends linearly in the radial direction, when seen in the axial direction. A side surface radially inward of the circumferential-side extending part 62b also extends linearly in the circumferential direction. Further, a side surface including the q-axis side of the radial-side extending part 62a and the radially outward side of the circumferential-side extending part 62b is curved and bulges toward an end part of the fixed magnetic-force magnet <NUM>. Thus, the second cavity part <NUM> is configured so that each of the width of the radial-side extending part 62a in the circumferential direction and the width of the circumferential-side extending part 62b in the radial direction changes according to a position in the extending direction.

The second cavity part <NUM> contacts the corresponding end of the fixed magnetic-force magnet <NUM> and the second auxiliary fixed magnetic-force magnet <NUM>. A part of the end surface 40b of the fixed magnetic-force magnet <NUM> radially outward of a part which contacts the second auxiliary fixed magnetic-force magnet <NUM> is exposed to the second cavity part <NUM>. Part of a radially outward side surface of the second auxiliary fixed magnetic-force magnet <NUM> is also exposed to the second cavity part <NUM>. Therefore, a first closure area <NUM> is formed in a radially outward part of each magnetic pole part <NUM>. The first closure area <NUM> is defined by the two second cavity parts <NUM> on both sides in the circumferential direction and the pole surface PF of the fixed magnetic-force magnet <NUM> as an inward side in the radial direction.

The first auxiliary fixed magnetic-force magnet <NUM> is disposed in the first closure area <NUM> in a state where both ends in the circumferential direction are brought close to the radial-side extending parts 62a. The distance between each end part of the first auxiliary fixed magnetic-force magnet <NUM> and each side surface of the radial-side extending part 62a on the d-axis side is the same. The second variable magnetic-force magnet <NUM> is disposed between a part of the rotor core <NUM> on the first variable magnetic-force magnet <NUM> side of the second cavity part <NUM> (i.e., a tip-end part of the circumferential-side extending part 62b) and the outer circumferential surface 32a of this rotor core <NUM>. The tip-end part of the circumferential-side extending part 62b is lower in the magnetic reluctance, as compared with other parts of the circumferential-side extending part 62b, because the tip-end part has a narrower width in the radial direction. Therefore, the second variable magnetic-force magnet <NUM> forms the magnetically in series relationship also with the fixed magnetic-force magnet <NUM> via the tip-end part of the circumferential-side extending part 62b during the magnetizing processing.

The second cavity part <NUM> contacts an end part of the corresponding second variable magnetic-force magnet <NUM>. A part of a radially inward end surface 52a of the second variable magnetic-force magnet <NUM> is exposed to the tip-end part of the circumferential-side extending part 62b. Therefore, a second closure area <NUM> is formed on both sides of the first closure area <NUM> in the circumferential direction of each magnetic pole part <NUM>. The second closure area <NUM> is formed by defining both sides in the circumferential direction and inside in the radial direction by the second cavity part <NUM> and the second variable magnetic-force magnet <NUM>.

Further, a flux path <NUM> is formed on both sides of the fixed magnetic-force magnet <NUM> in the circumferential direction of each magnetic pole part <NUM>. The flux path <NUM> is formed by defining the first pillar part <NUM> side in the circumferential direction and both sides in the radial direction by the first cavity part <NUM> and the second cavity part <NUM>. The second auxiliary fixed magnetic-force magnet <NUM> is disposed in the flux path <NUM> in a state where a radially inward end part is separated from the first cavity part <NUM> by a given distance. Therefore, the flux path <NUM> also extends radially inward of the fixed magnetic-force magnet <NUM>. The fixed magnetic-force magnet <NUM> and the first variable magnetic-force magnet <NUM> are configured to be magnetically in series by the flux path <NUM> during the magnetizing processing.

As described above, as for the drive motor <NUM>, the output which is stable in a wide operating range is demanded. From the viewpoint of improving energy efficiency (fuel efficiency, electricity efficiency), optimization of the power factor is demanded in this wide operating range. In addition, in the case of the variable magnetic force motor, the magnetizing direction is completely opposite with respect to the variable magnetic-force magnet <NUM> between the magnetizing processing and the demagnetizing processing.

Therefore, in order to realize an increase in the output and an improvement in the efficiency of the drive motor <NUM>, it is necessary to enable it to optimize the flow of the magnetic flux to various operation scenes, such as during the magnetizing processing, after the magnetizing processing, during the demagnetizing processing, after the demagnetizing processing, during the maximum torque output, and during operation at high power factor. The above-described structure of the rotor <NUM> is devised in order to realize the demand.

As described above, the large current which can be supplied to the drive motor <NUM> is limited. Therefore, under such limitation, the variable magnetic-force magnet <NUM> is preferred to be magnetized efficiently until the magnetic force reaches saturation. However, such magnetizing processing cannot be realized only by disposing the fixed magnetic-force magnet <NUM> and the variable magnetic-force magnet <NUM> at the fundamental positions.

<FIG> illustrates a structure of the rotor <NUM> according to a comparative example. In <FIG>, the upper figure is a schematic diagram and the lower figure is a view corresponding to the rotor <NUM> of this embodiment. During the magnetizing processing, a strong magnetizing magnetic field is applied to the variable magnetic-force magnet <NUM> as illustrated by arrows Ms. A magnetic flux according to this magnetizing magnetic field (magnetization magnetic flux) flows from the d-axis side of the S-magnetic pole part <NUM> to the d-axis side of the N-magnetic pole part 33N through the variable magnetic-force magnet <NUM>.

In the rotor <NUM> according to the comparative example, the second cavity part <NUM> and the second auxiliary fixed magnetic-force magnet <NUM> are not included at each magnetic pole part <NUM>. In this rotor <NUM>, a high-density magnetic flux flows radially outward at the N-magnetic pole part 33N from the pole surface PF (N-pole) radially outward of the fixed magnetic-force magnet <NUM>. A part of the magnetic flux repels mutually with the magnetization magnetic flux applied to the variable magnetic-force magnet <NUM> during the magnetizing processing. For this reason, the flux density of the magnetization magnetic flux which passes through the variable magnetic-force magnet <NUM> is reduced. As a result, the variable magnetic-force magnet <NUM> cannot be magnetized efficiently.

<FIG> illustrates a structure of the rotor <NUM> of this embodiment indicated corresponding to <FIG>. The magnetic reluctance of air is overwhelmingly high as compared with the magnetic reluctance of the rotor core <NUM>. Therefore, by forming the second cavity part <NUM>, a magnetic flux path in which the high-density magnetic flux which exits from the fixed magnetic-force magnet <NUM> and the magnetization magnetic flux repel mutually is intercepted in the N-magnetic pole part 33N. Further, the magnetic flux has a characteristic to flow by the shortest route. Therefore, in the N-magnetic pole parts 33N, a flow of the magnetization magnetic flux in the forward direction from the variable magnetic-force magnet <NUM> toward the fixed magnetic-force magnet <NUM> is formed by the flux path <NUM>.

The flow of the magnetization magnetic flux in the flux path <NUM> is guided by the curved surface 61a of the first cavity part <NUM>. Further, the magnetization magnetic flux which flows through the flux path <NUM> in the N-magnetic pole part 33N flows into the fixed magnetic-force magnet <NUM> from the radially outward pole surface PF (S-pole), and it is drawn into the fixed magnetic-force magnet <NUM> from the second auxiliary fixed magnetic-force magnet <NUM> due to the magnetic force of the second auxiliary fixed magnetic-force magnet <NUM>. Therefore, it also flows in from the circumferential end surface of this fixed magnetic-force magnet <NUM>. Thus, the flow of the magnetization magnetic flux between the fixed magnetic-force magnet <NUM> and the variable magnetic-force magnet <NUM> is serialized. Therefore, in the magnetizing processing, the magnetization magnetic flux can be collected to the variable magnetic-force magnet <NUM>. As a result, by the magnetizing processing, the variable magnetic-force magnet <NUM> can be magnetized efficiently until the magnetic force reaches saturation, even under the limited condition.

<FIG> illustrates magnetic flux lines when applying d-axis current to the coil <NUM> of the stator <NUM> by the magnetizing processing. Further, <FIG> illustrates a contour diagram of the flux density according to the magnetizing magnetic field during the magnetizing processing. <FIG> and <FIG> are views based on a result of a simulation using a magnetic field analysis program. As illustrated in <FIG>, in the drive motor <NUM>, during the magnetizing processing, a strong magnetizing magnetic field occurs in the coil <NUM> of the stator <NUM>, and the magnetizing magnetic field acts on the first variable magnetic-force magnet <NUM> and the second variable magnetic-force magnet <NUM>.

At this time, a part of the magnetization magnetic flux enters into the second closure area <NUM> of the S-magnetic pole part <NUM> from the stator <NUM> side, passes through the second variable magnetic-force magnet <NUM> of the S-magnetic pole part <NUM>, the first variable magnetic-force magnet <NUM>, and the second variable magnetic-force magnet <NUM> of the N-magnetic pole part 33N from the second closure area <NUM>, and exits from the second closure area <NUM> of the N-magnetic pole part 33N to the stator <NUM> side. The magnetization magnetic flux which passed through the flux path <NUM> of the S-magnetic pole part <NUM> also enters into the first variable magnetic-force magnet <NUM>. A part of the magnetization magnetic flux which exited from the first variable magnetic-force magnet <NUM> passes through the flux path <NUM> of the N-magnetic pole part 33N. Further, a part of the magnetization magnetic flux which passed through the second variable magnetic-force magnet <NUM> penetrates the tip-end part of the circumferential-side extending part 62b, and flows into the flux path <NUM> of the N-magnetic pole part 33N.

The magnetization magnetic flux which flows through the flux path <NUM> enters directly into the fixed magnetic-force magnet <NUM> from the radially inward pole surface PF (S-pole), or enters from the circumferential end surface via the second auxiliary fixed magnetic-force magnet <NUM>. Further, the magnetization magnetic flux which exited from the fixed magnetic-force magnet <NUM> flows to the stator <NUM> side through the first closure area <NUM>. A part of the magnetization magnetic flux passing through the first closure area <NUM> is converged into the first auxiliary fixed magnetic-force magnet <NUM>, and other parts pass through the side of the first auxiliary fixed magnetic-force magnet <NUM> in the circumferential direction, and exit to the stator <NUM> side. At this time, a part of the magnetization magnetic flux penetrates the tip-end side of the radial-side extending part 62a, and flows to the stator side.

In such a magnetizing magnetic field, in the N-magnetic pole parts 33N, the high-density magnetic flux which exits from the radially outward pole surface PF (N-pole) of the fixed magnetic-force magnet <NUM> is limited in the flow in the circumferential direction in the first closure area <NUM> by the two second cavity parts <NUM>. Thus, a part of the magnetic flux which exits from the fixed magnetic-force magnet <NUM> and the magnetization magnetic flux which flows through the second closure area <NUM> repelling each other is suppressed. Further, as described above, the magnetization magnetic flux flows in series between the fixed magnetic-force magnet <NUM> and the first variable magnetic-force magnet <NUM> (see arrows in <FIG>). Therefore, as illustrated in <FIG>, the magnetization magnetic flux is collected to the first variable magnetic-force magnet <NUM>, and the flux density of the magnetization magnetic flux which passes through the first variable magnetic-force magnet <NUM> is increased.

In the rotor <NUM> of this embodiment, the first cavity part <NUM> and the second cavity part <NUM> are formed in the rotor core <NUM> at each magnetic pole part <NUM>. The first cavity part <NUM> extends between a position radially inward of the fixed magnetic-force magnet <NUM> and a position radially inward of the first variable magnetic-force magnet <NUM>. On the other hand, the second cavity part <NUM> is separated radially outward from the first cavity part <NUM>, and it extends toward the first variable magnetic-force magnet <NUM> in the circumferential direction from a position radially outward of a surface on the first variable magnetic-force magnet <NUM> side of the fixed magnetic-force magnet <NUM>. The flux path <NUM> which is comprised of a part of the rotor core <NUM> is formed between the first cavity part <NUM> and the second cavity part <NUM>. Because of this flux path <NUM>, the fixed magnetic-force magnet <NUM> and the first variable magnetic-force magnet <NUM> can form the magnetically in series relationship. Therefore, in the magnetizing processing, it can be suppressed that the magnetic flux from the fixed magnetic-force magnet <NUM> and the magnetization magnetic flux which passes through the first variable magnetic-force magnet <NUM> repel each other, and thereby, the magnetization magnetic flux can be efficiently collected to the first variable magnetic-force magnet <NUM>. Therefore, the flux density applied to the first variable magnetic-force magnet <NUM> can be increased by the magnetizing processing.

In the rotor <NUM> of this embodiment, each magnetic pole part <NUM> includes the second variable magnetic-force magnet <NUM>. The second variable magnetic-force magnet <NUM> is disposed between the part of the second cavity part <NUM> on the first variable magnetic-force magnet <NUM> side in the rotor core <NUM> and the outer circumferential surface 32a of the rotor core <NUM>. Further, since the magnetizing direction of the second variable magnetic-force magnet <NUM> is oriented in the circumferential direction similarly to the first variable magnetic-force magnet <NUM>, the second variable magnetic-force magnet <NUM> can form the magnetically in series relationship with the fixed magnetic-force magnet <NUM> and the first variable magnetic-force magnet <NUM>. Therefore, in the magnetizing processing, at least a part of the magnetization magnetic flux passes through the second variable magnetic-force magnet <NUM> between the fixed magnetic-force magnet <NUM> and the first variable magnetic-force magnet <NUM>. This collects the magnetization magnetic flux to the first variable magnetic-force magnet <NUM> further efficiently, which is advantageous to an increase in the flux density applied to the first variable magnetic-force magnet <NUM> by the magnetizing processing.

In the rotor <NUM> of this embodiment, each magnetic pole part <NUM> includes the first auxiliary fixed magnetic-force magnet <NUM>. The first auxiliary fixed magnetic-force magnet <NUM> is disposed between the fixed magnetic-force magnet <NUM> of the rotor core <NUM> and the outer circumferential surface 32a of this rotor core <NUM>. Further, since the magnetizing direction of the first auxiliary fixed magnetic-force magnet <NUM> is oriented to the same direction as the fixed magnetic-force magnet <NUM>, the first auxiliary fixed magnetic-force magnet <NUM> can form the magnetically in series relationship with the fixed magnetic-force magnet <NUM> and the first variable magnetic-force magnet <NUM>. Therefore, the magnetic force of the fixed magnetic-force magnet <NUM> is reinforced by the first auxiliary fixed magnetic-force magnet <NUM>. Further, in the magnetizing processing, the magnetization magnetic flux passes through the first auxiliary fixed magnetic-force magnet <NUM> between the fixed magnetic-force magnet <NUM> and the stator <NUM>. These are advantageous to a further efficient collection of the magnetization magnetic flux to the first variable magnetic-force magnet <NUM>, and an increase in the flux density applied to the first variable magnetic-force magnet <NUM> by the magnetizing processing.

As described above, the desirable embodiment is described as illustration of the art of the present disclosure. However, the art of the present disclosure is not limited to the embodiment, but it may also be applied to other embodiments in which any of change, replacement, addition, abbreviation, etc. is suitably made to the embodiment. Further, regarding the embodiment, it should be appreciated by the person skilled in the art that various modifications are possible without departing from the scope of the present disclosure, and such modifications also belong to the scope of the present disclosure.

Although in the embodiment the hybrid vehicle is illustrated, it is not limited to the hybrid vehicle. The automobile to which the art of the present disclosure is applied may be an electric vehicle which does not carry the engine 2E but travels only by the drive motor <NUM>. Further, the rotary electric machine according to the art of the present disclosure may also be applied to railroad vehicles other than automobiles, and may be used for apparatuses other than for vehicles, such as refrigerators and laundry machines.

Claim 1:
A rotor (<NUM>), comprising:
a rotor core (<NUM>); and
a plurality of magnetic pole parts (<NUM>) provided to the rotor core (<NUM>),
wherein the plurality of magnetic pole parts (<NUM>) are lined up along an outer circumferential surface of the rotor core (<NUM>),
wherein the rotor (<NUM>) is combined with a stator (<NUM>) disposed radially outward of the rotor core (<NUM>), and a magnetic force of the plurality of magnetic pole parts (<NUM>) is changeable by a given magnetic flux generated by the stator (<NUM>), and
wherein each magnetic pole part (<NUM>) of the plurality of magnetic pole parts (<NUM>) includes:
a fixed magnetic-force magnet (<NUM>) disposed so that a magnetizing direction thereof is oriented in a radial direction of the rotor core (<NUM>):
first variable magnetic-force magnets (<NUM>) disposed at positions radially outward of the fixed magnetic-force magnet (<NUM>) on both sides of the fixed magnetic-force magnet (<NUM>) in a circumferential direction of the rotor core (<NUM>) so that magnetizing directions thereof are oriented in the circumferential direction, a magnetization state of the first variable magnetic-force magnets (<NUM>) being changeable by the given magnetic flux;
a first cavity part (<NUM>) formed in the rotor core (<NUM>) so as to extend between a position radially inward of the fixed magnetic-force magnet (<NUM>) and a position radially inward of the first variable magnetic-force magnets (<NUM>);
characterized in that each magnetic pole part (<NUM>) of the plurality of magnetic pole parts (<NUM>) additionally includes:
a second cavity part (<NUM>) formed in the rotor core (<NUM>) so as to be separated radially outward from the first cavity part (<NUM>), the second cavity part (<NUM>) extending toward the first variable magnetic-force magnet (<NUM>) in the circumferential direction from a position radially outward of a surface on a first variable magnetic-force magnet side of the fixed magnetic-force magnet (<NUM>).