A rotor punching sheet, a rotor iron core, a rotor, an electric motor and a vehicle are provided. The rotor punching sheet has a punching sheet body, a shaft hole and a plurality of slot groups. The shaft hole is provided in the punching sheet body. The plurality of slot groups are provided in the punching sheet body. Each slot group has at least one magnetic slot. Each magnetic slot has two magnet slots. Each magnet slot has a first slot end and a second slot end, which are on the axial end face, the first slot end being disposed closer to the shaft hole than the second slot end. A peripheral edge of the punching sheet body has a peripheral section on the axial end face. The peripheral section has a plurality of arc-shaped sections connected to each other and corresponding to the plurality of slot groups. Each arc-shaped section has a first circular arc section concentric with the shaft hole, and a second circular arc section eccentric from the shaft hole.

FIELD

The present application relates to the field of electric motor equipment, and more particularly, to a rotor punching sheet, a rotor iron core, a rotor, an electric motor, and a vehicle.

BACKGROUND

In the prior art, rotor components of a built-in permanent magnet electric motor include rotor punching sheets. As a key component of a rotor, the rotor punching sheets should be properly designed because it directly determines the performance of the electric motor.

Otherwise, an improper design of the rotor punching sheets leads to more harmonic waves in the air-gap magnetic field of the electric motor and a serious distortion, which results in high torque pulsation and significant vibration noise. Therefore, how to properly design the rotor to improve the performance of the electric motor is an urgent problem to be solved.

SUMMARY

It is an object of the present application to solve at least one of the technical problems existing in the prior art or related art.

To this end, in a first aspect of the present application, a rotor punching sheet is provided.

In a second aspect of the present application, a rotor iron core is provided.

In a third aspect of the present application, a rotor is provided.

In a fourth aspect of the present application, an electric motor is provided.

In a fifth aspect of the present application, a vehicle is provided.

In view of the above, the rotor punching sheet provided in the first aspect of the present application includes a punching sheet body, a shaft hole, and a plurality of slot groups, where the shaft hole is provided on the punching sheet body. The plurality of slot groups are provided on the punching sheet body, each slot group includes at least one magnetic slot, each magnetic slot includes two magnet slots, each magnet slot includes a first slot end and a second slot end on an axial end face, and the first slot end is arranged closer to the shaft hole than the second slot end. Herein, a peripheral edge of the punching sheet body includes a peripheral section on the axial end face, the peripheral section includes a plurality of connected arc-shaped sections corresponding to the plurality of slot groups, each arc-shaped section includes a first circular arc section concentric with the shaft hole and a second circular arc section eccentric with the shaft hole.

The rotor punching sheet provided herein includes an punching sheet body, an shaft hole, and an plurality of slot groups. The shaft hole is provided on the punching sheet body, and the punching sheet body is made of magnetic steel. The shaft hole is configured to assemble the rotating shaft of the rotor. The plurality of slot groups are set around the shaft hole on the punching sheet body. It is to be noted that all or some of the plurality of installations may have the same structure, and can be adjusted according to actual needs. Each slot group includes at least one magnetic slot, each magnetic slot includes two magnet slots, and each magnet slot is configured to install a permanent magnet of the rotor; each magnet slot includes an first slot end and an second slot end on the axial end face, and the first slot end is arranged closer to the shaft hole than the second slot end. When a distance between the first slot ends of the two magnet slots is not equal to the distance between the second slot ends of the two magnet slots, the two magnet slots are arranged in a V-shape on the punching sheet body. The openings of the two magnet slots in the V-shaped arrangement are facing away from the shaft hole. Further, the peripheral edge of the punching sheet body includes an peripheral section on the axial end face, the peripheral section being a segment with definite endpoints. The outer peripheral section includes a plurality of connected arc-shaped sections, one arc-shaped section corresponds to one slot group; it is to be noted that the number of the arc-shaped sections and the number of the slot groups are equal to the number of magnetic poles of the electric motor. By configuring that each arc-shaped section includes at least the first circular arc section concentric with the shaft hole and the second circular arc section eccentric with the shaft hole, an cyclically changing unequal air gap along a circumferential direction can be formed between the outer circumference circle of the rotor and the inner circumference circle of the stator for the electric motor. This can result in alternating a left arc section, the first circular arc section, and a right arc section on the outer circumference circle of the rotor punching sheet, making the electric motor run more stable. Moreover, optimizing the distribution of a magnetic field of the rotor, effectively reducing the Q-axis and D-axis armature reaction, effectively improving the torque pulsation of the electric motor while keeping a peak torque of the electric motor unchanged, reducing the vibration noise of the electric motor in operation, rendering a better user experience. In addition, it also to a certain extent reduces the iron losses of the stator and the rotor of the electric, which is beneficial to improve the efficiency of the electric motor. Furthermore, the combination of the first circular arc section and the second circular arc section takes into account the advantages of both a full-circle design and a completely eccentric design of the rotor punching sheet. Without changing the average length of the air gap of the electric motor and the peak torque of the electric motor, an air-gap magnetic field is effectively improved and then an air-gap magnetic density and a sinusoidal degree of a counter electromotive force waveform are increased; a proportion of harmonic waves is reduced, the torque pulsation is reduced, and the vibration noise of the electric motor is significantly reduced. In the present application, at least one V-shaped magnetic slot is correspondingly provided at each magnetic pole of the electric motor, and each arc-shaped section at least includes the concentric first circular arc section and the eccentric second circular arc section, thereby making the overall structural layout of the rotor punching sheet more reasonable, and making the distribution of the air-gap magnetic density of the electric motor more effectively improved on the basis of ensuring an output torque of the electric motor, which can also reduce the proportion of harmonic waves for the electric motor; therefore, the problem of the torque pulsation and vibration noise of the electric motor can be solved, and a design of an electric motor with excellent performance can be achieved.

In another embodiment, further, either of the two magnet slots includes a straight slot section that is connected between the first slot end and the second slot end and is closer to another of the two magnet slots, the straight slot section includes a distal end away from the shaft hole, lines connecting the distal ends of the two magnet slots to a center of the shaft hole, respectively, form a polar arc angle α, and a central angle of the first circular arc section is β, and

In this embodiment, for the two magnet slots in one magnetic slot, either of the magnet slots includes two straight sections connected between the first slot end and the second slot end, with one of the two straight sections closer to the other magnet slot being the straight slot section. That is to say, the two magnet slots include a first magnet slot and a second magnet slot, where the first magnet slot includes a straight slot section facing the second magnet slot, the second magnet slot includes a straight slot section facing the first magnet slot, either straight slot section includes a distal end away from the shaft hole, and an included angle formed by lines connecting the distal ends of the first magnet slot and the second magnet slot to the center of the shaft hole, respectively, is the polar arc angle α.

Furthermore, a center of a circle on which the first circular arc section is located coincides with the center of the shaft hole, and the central angle β corresponding to the first circular arc section refers to an included angle between the lines connecting two endpoints of the first circular arc section to the center of the shaft hole, respectively. In some embodiments, a line connecting an endpoint of the first circular arc section to the center of the shaft hole is denoted as a first connection line, a line connecting the other endpoint of the first circular arc section to the center of the shaft hole is denoted as a second connection line, and an included angle between the first connection line and the second connection line is the central angle β.

Furthermore, a ratio of polar arc angle α to the central angle β has a great influence on the peak torque, torque pulsation and air-gap magnetic field of the electric motor. When β/α is smaller, a waveform distortion rate of the air-gap magnetic field of the electric motor is smaller, and the torque pulsation is lower, but the torque and power of the electric motor are lower, too. When β/α is larger, the waveform distortion of the air-gap magnetic field is greater, and the torque pulsation of the electric motor is higher. Therefore, a proper value of β/α plays an important role in the performance of the electric motor. By defining β/α in the above range, optimization of many aspects such as the torque, torque pulsation, and air gap harmonic wave of the electric motor can be achieved. Without changing the torque of the electric motor, the proportion of the harmonic waves can be effectively reduced, and the problem of the torque pulsation can be addressed for the electric motor.

In another embodiment, furthermore, the number of the second circular arc sections is two, and the two second circular arc sections are connected on both sides of the first circular arc section, respectively.

In this embodiment, the two second circular arc sections are connected on both sides of the first circular arc section, respectively. In some embodiments, the two second circular arc sections include the left arc section and the right arc section, that is, for one magnetic pole of the electric motor, the arc-shaped sections include the left arc section, the first circular arc section, and the right arc section that are connected in sequence. For the adjacent magnetic poles, the left arc section of a magnetic pole is connected to the right arc section of an adjacent magnetic pole, and the right arc section of a magnetic pole is connected to the left arc section of an adjacent magnetic pole. Furthermore, a center of the second circular arc section does not coincide with the center of the shaft hole, that is to say, the peripheral edge of the punching sheet body is formed by combining the first circular arc section concentric with the center of the shaft hole and the second circular arc section eccentric with the center of the shaft hole; therefore, an unequal air gap periodically varying along a circumferential direction can be formed between an outer circumference circle of the rotor and an inner circumference circle of the stator for the electric motor, and accordingly, the left arc section, the first circular arc section, and then the right arc section can alternate on an outer circumference circle of the rotor punching sheet and then the operation of the electric motor can be more stable. Moreover, the distribution of a magnetic field of the rotor is optimized, and a Q-axis and D-axis armature reaction is effectively weakened, which effectively addresses the problem of the torque pulsation of the electric motor while keeping a peak torque of the electric motor unchanged; as such, the vibration noise of the electric motor in operation is reduced, rendering a better user experience. In addition, the stator and the rotor of the electric motor suffer from less iron loss, which is beneficial to improve the efficiency of the electric motor. Furthermore, the combination of the first circular arc section and the second circular arc section takes into account the advantages of both a full-circle design and a completely eccentric design of the rotor punching sheet. With an average length of the air gap of the electric motor unchanged and the peak torque of the electric motor unchanged, an air-gap magnetic field is effectively improved and then an air-gap magnetic density and a sinusoidal degree of a counter electromotive force waveform are increased; a proportion of harmonic waves is reduced, for reducing the torque pulsation, and significantly reducing the vibration noise of the electric motor.

In another embodiment, furthermore, the second circular arc section includes at least one eccentric circular arc section.

In this embodiment, each second circular arc section includes at least one eccentric circular arc section. In the case that the second circular arc section includes one eccentric circular arc section, the arc-shaped section includes one first circular arc section and two eccentric circular arc sections for one magnetic pole of the electric motor. In the case that the second circular arc section includes two eccentric circular arc sections, the arc-shaped section includes one first circular arc section and four eccentric circular arc sections for one magnetic pole of the electric motor. That is to say, the number of the circular arc sections in the arc-shaped section may be three, five, seven, etc. In the case of multiple eccentric circular arc sections, for one arc-shaped section, multiple varying unequal air gaps can be formed between the outer circumference circle of the rotor of the rotor punching sheet and the inner circumference circle of the stator, which is beneficial to the stable operation of the electric motor. Moreover, the distribution of the magnetic field of a rotor with the rotor punching sheet is optimized, and the Q-axis and D-axis armature reaction is effectively weakened, which effectively addresses the problem of the torque pulsation of the electric motor while keeping the peak torque of the electric motor unchanged; as such, the vibration noise of the electric motor in operation is reduced, rendering a better user experience.

In another embodiment, furthermore, the number of the at least one magnetic slot is two, the first slot ends of the two magnet slots of each magnetic slot are close to each other, and the second slot ends of the two magnet slots of each magnetic slot are away from each other; the two magnetic slots include a first magnetic slot and a second magnetic slot, the first magnetic slot is arranged closer to the shaft hole than the second magnetic slot, and the second magnetic slot forms the polar arc angle α, where the first magnetic slot and the second magnetic slot are symmetrical with respect to a center line of a magnetic pole where they are located.

In this embodiment, for one magnetic pole of the electric motor, the slot group includes two magnetic slots, the first slot ends of the two magnet slots in each magnetic slot are close to each other, and the second slot ends of the two magnet slots in each magnetic slot are away from each other, that is, the two magnetic slots are both V-shaped slots, and slot openings of the V-shaped slots formed by the two magnet slots in each magnetic slot all face the peripheral edge of the punching sheet body, i.e., face away from the shaft hole. Furthermore, the two magnetic slots include the first magnetic slot and the second magnetic slot, and the first magnetic slot is arranged closer to the shaft hole than the second magnetic slot, that is, the first slot end of the magnet slot in the second magnetic slot is arranged closer to the shaft hole than the first slot end of the magnet slot in the second magnetic slot. It is to be noted that in the case that the number of magnetic slots is two, the polar arc angle α mentioned in the foregoing embodiment refers to an angle formed by the two magnet slots of the second magnetic slot. That is to say, the two magnet slots of the second magnetic slot include the first magnet slot and the second magnet slot, the first magnet slot includes a straight slot section facing the second magnet slot, the second magnet slot includes a straight slot section facing the first magnet slot, either straight slot section includes a distal end away from the shaft hole, and an included angle formed by lines connecting the distal ends of the first magnet slot and the second magnet slot to the center of the shaft hole, respectively, is the polar arc angle α. Furthermore, the first magnetic slot and the second magnetic slot are symmetrical with respect to a center line of a magnetic pole where they are and then the electric motor having the rotor punching sheet can be simply constructed, easily manufactured, and produced with low costs.

In another embodiment, furthermore, an included angle formed by extension lines of the straight slot sections of the two magnet slots in the first magnetic slot is a first opening angle, an included angle formed by the extension lines of the straight slot sections of the two magnet slots in the second magnetic slot is a second opening angle, and the first opening angle is not equal to the second opening angle.

In this embodiment, the included angle formed by the extension lines of the straight slot sections of the two magnet slots in the first magnetic slot is the first opening angle, the included angle formed by the extension lines of the straight slot sections of the two magnet slots in the second magnetic slot is the second opening angle, and the first opening angle is not equal to the second opening angle; as such, the magnetic field strength of each magnetic pole is better increased for magnetism gathering, and a ratio of the Q-axis inductance to the D-axis inductance of the electric motor is further increased with the increase the output torque of the electric motor, for increasing a reluctance torque component, and improving a field-weakening speed expansion capability of the electric motor. In some embodiments, the first opening angle is larger than the second opening angle, or the first opening angle is smaller than the second opening angle.

In another embodiment, furthermore, the first opening angle is smaller than the second opening angle.

In this embodiment, the first opening angle of the first magnetic slot closer to the shaft hole is smaller than the second opening angle of the second magnetic slot away from the shaft hole; as such, the magnetic field strength of each magnetic pole is better increased for magnetism gathering, and the ratio of the Q-axis inductance to the D-axis inductance of the electric motor is further increased with the increase the output torque of the electric motor, for increasing the reluctance torque component, and improving the field-weakening speed expansion capability of the electric motor.

In another embodiment, furthermore, the first circular arc section is symmetrical with respect to the center line of the magnetic pole where it is. The two second circular arc sections are symmetrical with respect to the center line of the magnetic pole where they are located.

In this embodiment, the first circular arc section is symmetrical with respect to the center line of the magnetic pole where it is. The two second circular arc sections are symmetrical with respect to the center line of the magnetic pole where they are located. That is to say, each arc-shaped section is symmetrical with respect to the center line of the magnetic pole where it is and then a periodically varying unequal air gap is formed between the peripheral edge composed of a plurality of arc-shaped sections of the whole punching sheet body and the inner peripheral circle of the stator. With an average length of the air gap of the electric motor unchanged and the peak torque of the electric motor unchanged, an air-gap magnetic field is effectively improved and then an air-gap magnetic density and a sinusoidal degree of a counter electromotive force waveform are increased; a proportion of harmonic waves is reduced, for reducing the torque pulsation, and significantly reducing the vibration noise of the electric motor. In addition, by arranging the arc-shaped section to be symmetrical with respect to the center line of the magnetic pole, the rotor punching sheet is less difficult to be manufactured, and the product yield is improved.

In another embodiment, furthermore, lengths of the first circular arc sections of the plurality of arc-shaped sections are equal. Radiuses of circles on which the first circular arc sections of the plurality of arc-shaped sections are located are equal.

In this embodiment, the lengths of the first circular arc sections of the plurality of arc-shaped sections are equal, which can further ensure that there is a periodically varying unequal air gap between the outer circumference circle of the rotor and the inner circumference circle of the stator. With an average length of the air gap of the electric motor unchanged and the peak torque of the electric motor unchanged, an air-gap magnetic field is effectively improved. Furthermore, the radiuses of the circles on which the first circular arc sections of the plurality of arc-shaped sections are located are all equal, that is, the plurality of first circular arc sections are those on one circle. As such, a projection of a maximum outer contour of the rotor punching sheet on the axial end face can be in a regular shape and then the space required for the rotor with the rotor punching sheet during high-speed rotation is relatively regular, that is, in a cylindrical shape, which facilitates the machining preparation of the stator adapted thereto.

In another embodiment, furthermore, the center of the second circular arc section is on the punching sheet body.

In this embodiment, the center of the second circular arc section is on the punching sheet body, that is, the second circular arc section projects face away from the shaft hole. In other words, the centers of the first circular arc section and the second circular arc section are both on the punching sheet body, and the first circular arc section and the second circular arc section are bent in a similar trend and then it is more feasible to enable a periodically varying air gap between the outer circumference circle of the rotor and the inner circumference circle of the stator along a circumference, for making the operation of the electric motor to be more stable. Moreover, the distribution of a magnetic field of the rotor is optimized, and a Q-axis and D-axis armature reaction is effectively weakened, which effectively addresses the problem of the torque pulsation of the electric motor while keeping a peak torque of the electric motor unchanged; as such, the vibration noise of the electric motor in operation is reduced, rendering a better user experience.

In another embodiment, furthermore, the slot groups include an auxiliary slot provided on the peripheral edge of the punching sheet body.

In this embodiment, each slot group has the auxiliary slot, and the auxiliary slot is provided on the peripheral edge of the punching sheet body. The auxiliary slot can effectively reduce the proportion of harmonic waves in the air-gap magnetic field of the electric motor to improve a sinusoidal degree of an air-gap magnetic density waveform, and address the problem of the torque pulsation of the electric motor, which in turn can reduce a radial force caused by the harmonic wave, reduce the running noise of the electric motor, and solve the problem of the vibration noise of the electric motor, for rendering a better user experience. In addition, by providing concave auxiliary slots on the rotor punching sheet in the present application, it is also possible to partially adjust the no-load counter electromotive force waveform and radial force of the electric motor, to reduce a maximum no-load line counter electromotive force of the electric motor. It is to be noted that the torque pulsation of the electric motor largely depends on a non-sinusoidal degree of the air-gap magnetic field, and a larger proportion of harmonic waves in the air-gap magnetic field leads to a worse output torque waveform of the electric motor, in which case, the greater the torque pulsation, the greater the vibration noise.

In another embodiment, furthermore, the auxiliary slot is provided in plurality, and the plurality of auxiliary slots are arranged at intervals and are symmetrically arranged along the center line of the magnetic pole where they are located.

In this embodiment, each slot group includes a plurality of auxiliary slots, in some embodiments, one slot group may be provided with four auxiliary slots, the plurality of auxiliary slots being arranged at intervals on the punching sheet body. The plurality of auxiliary slots of one slot group are arranged symmetrically along the center line of the magnetic pole, and at least two auxiliary slots are provided and arranged in pairs.

In another embodiment, furthermore, the auxiliary slots include two first auxiliary slots, and the two first auxiliary slots are arranged symmetrically on the first circular arc section along the center line of the magnetic pole where they are located. In addition/in some embodiments, the auxiliary slots further include two second auxiliary slots, and the two second auxiliary slots are respectively provided on two second circular arc sections symmetrically along the center line of the magnetic pole where they are located.

In this embodiment, the auxiliary slots include two first auxiliary slots and two second auxiliary slots, where the two first auxiliary slots are symmetrically arranged on the first circular arc section along the center line of the magnetic pole, the two second auxiliary slots are arranged on the second circular arc section along the center line of the magnetic pole, and the two second auxiliary slots are arranged on two different arc-shaped sections, respectively.

Furthermore, a slot depth of the first auxiliary slot is greater than a slot depth of the second auxiliary slot, that is, in the case of the concentric first circular arc section, the slot depth of the first auxiliary slot is greater, and in the case of the eccentric second circular arc section, the slot depth of the second auxiliary slot is smaller; through the combination of the first auxiliary slot and the second auxiliary slot with different slot depths, it is possible to further reduce the proportion of harmonic waves in the air-gap magnetic field, for improving the sinusoidal degree of the air-gap magnetic density waveform, and addressing the problem of the torque pulsation and the radial force; moreover, the arrangement of the auxiliary slots can also partially adjust the no-load counter electromotive force waveform, to reduce the amplitude of the maximum no-load line counter electromotive force of the electric motor.

In another embodiment, the first auxiliary slot further has a slot depth in the range of 0.5 mm-0.9 mm. In addition/in some embodiments, the slot depth of the second auxiliary slot is in the range of 0.1 mm-0.7 mm.

In this embodiment, as long as the slot depths of the first auxiliary slot and the second auxiliary slot fall within the above range, a small volume of the auxiliary slot can be ensured with the performance of the electric motor effectively improved by the auxiliary slot, preventing the auxiliary slot from causing a large change in the shape of the peripheral edge of the punching sheet body.

According to the second aspect of the present application, a rotor iron core is provided, including the rotor punching sheet provided by any of the above embodiments, where the rotor punching sheet is provided in plurality, the plurality of rotor punching sheets are stacked, and the plurality of slot groups of the plurality of rotor punching sheets are axially aligned to form a plurality of insertion slots.

The rotor iron core provided by the present application includes the rotor punching sheet provided by any of the above embodiments, and thus has all the advantageous effects of the rotor punching sheet, which will not be described in detail herein.

According to the third aspect of the present application, a rotor is provided, including the rotor iron core provided by any of the above embodiments, where the rotor further includes a plurality of permanent magnets, each of the plurality of permanent magnets being inserted in the plurality of insertion slots.

The rotor provided by the present application includes the rotor iron core provided by any of the above embodiments, and thus has all the advantageous effects of the rotor iron core, which will not be described in detail herein.

According to the fourth aspect of the present application, an electric motor is provided, including the rotor provided by any of the above embodiments, where the electric motor further includes a stator, the stator including a mounting cavity extending axially therethrough, the rotor being located within the mounting cavity.

The electric motor provided by the present application includes the rotor provided by any of the above embodiments, and thus has all the advantageous effects of the rotor, which will not be described in detail herein.

In another embodiment, furthermore, a minimum spacing between an outer peripheral wall of the rotor and an inner peripheral wall of the stator is H1, and a maximum spacing between the outer peripheral wall of the rotor and the inner peripheral wall of the stator is H2, where 0.15 mm≤H2−H1≤0.35 mm.

In this embodiment, the minimum spacing between the outer peripheral wall of the rotor and the inner peripheral wall of the stator is H1. In some embodiments, there is a minimum spacing H1 between a point on the first circular arc section of the rotor punching sheet and the inner peripheral wall of the stator, because the radius of the circle on which the first circular arc section of the rotor punching sheet is located is larger, that is, a distance L1 between a point on the first circular arc section to the center of the shaft hole is larger. The maximum distance between the peripheral wall of the rotor and the inner peripheral wall of the stator is H2. In some embodiments, there is a maximum distance between a point on the second circular arc section of the rotor punching sheet and the inner peripheral wall of the stator, because a distance L2 between a point on the second circular arc section of the rotor punching sheet and the center of the shaft hole is smaller, that is, L2 is smaller than L1. Given that a radius of a projection of the inner peripheral wall of the stator on the axial end face is R (i.e., a radius of an inner circle of the stator), then the minimum spacing H1=R−L1, and the maximum spacing H2=R−L2, hence H2 is greater than H1.

In some embodiments, a difference between H1 and H2 not only directly determines an equivalent air gap length of the electric motor and affects the air-gap magnetic field distribution, but also directly determines a salient pole ratio of the electric motor and affects the peak torque and high-speed performance of the electric motor. In some embodiments, the torque pulsation of the electric motor mainly depends on the 5th, 7th, 11thand 13thharmonic waves of the air-gap magnetic field. In the case of a larger difference between H1 and H2, the air-gap magnetic field waveform is more sinusoidal, a harmonic wave amplitude of the electric motor is smaller, and the torque pulsation is lower, but the peak torque of the electric motor is also lower. The peak torque of the electric motor consists of the reluctance torque component and a permanent magnet torque component, where the permanent magnet torque of the electric motor is proportional to an amount of the permanent magnet, and the reluctance torque is proportional to the saliency ratio. Herein, the saliency ratio is a ratio of the Q-axis inductance to the D-axis inductance and is directly related to the difference between H1 and H2. Under the condition that the amount of the permanent magnet is constant, a proper distribution of the difference between H1 and H2 ensures that the equivalent air gap length of the electric motor keeps unchanged, and the salient ratio of the electric motor does not change, for ensuring that the peak torque of the electric motor does not change. Therefore, a solution allowing for a smaller proportion of harmonic waves, a lower torque pulsation, and better electromagnetic performance can be achieved under the same peak torque.

In another embodiment, furthermore, the number of magnetic poles of the electric motor is P, a maximum distance between the center of the shaft hole in the rotor punching sheet of the electric motor and the peripheral edge of the punching sheet body is L1, a minimum distance between the center of the shaft hole and the peripheral edge of the punching sheet body is L2, and a radius of an arc where the center of the second circular arc section of the rotor punching sheet is located is r, where r satisfies the following equation: r=L1−L2.

In this embodiment, the number of magnetic poles of the electric motor is P, the maximum distance between the center of the shaft hole in the rotor punching sheet of the electric motor and the peripheral edge of the punching sheet body is L1, the minimum distance between the center of the shaft hole and the peripheral edge of the punching sheet body is L2, and the radius of the arc where the center of the second circular arc section of the rotor punching sheet is located is r, where r satisfies the above equation. As such, the center of the eccentric circular arc section in the second circular arc section is located in the circle taking the center of the shaft hole as the center and r as the radius. The center of the second circular arc section cannot coincide with the center of the shaft hole. By defining a position of the center of the eccentric circular arc section, the combination of the concentric first circular arc section and the eccentric second circular arc section is thus more reasonable, and takes into account the advantages of both a full-circle design and a completely eccentric design of the rotor punching sheet. With an average length of the air gap of the electric motor unchanged and the peak torque of the electric motor unchanged, an air-gap magnetic field is effectively improved and then an air-gap magnetic density and a sinusoidal degree of a counter electromotive force waveform are increased; a proportion of harmonic waves is reduced, for reducing the torque pulsation, and significantly reducing the vibration noise of the electric motor. According to the fifth aspect of the present application, a vehicle is provided, including the electric motor provided by any of the above embodiments.

The vehicle provided by the present application includes the electric motor provided by any of the above embodiments, and thus has all the advantageous effects of the electric motor, which will not be described in detail herein. Additional aspects and advantages of the present application will be set forth in part in the detailed description which follows or may be learned by practicing the present application.

DETAILED DESCRIPTION OF EMBODIMENTS

In order that the above objects, features and advantages of the present application may be more clearly understood, a detailed description of the present application will be provided with reference to embodiments thereof which are illustrated in the appended drawings. It should be noted that the embodiments and features of the embodiments of the present application can be combined with each other without conflict.

In the following description, numerous exemplary details are set forth in order to provide a thorough understanding of the present application. However, the present application may be practiced otherwise than as in some embodiments described herein. Accordingly, the scope of the present application is not limited by the exemplary embodiments disclosed below.

A rotor punching sheet10, a rotor iron core, a rotor, an electric motor20, and a vehicle provided according to some embodiments of the present application are described below with reference toFIGS.1to9.

According to a first aspect of the present application, a rotor punching sheet10is provided, as shown inFIGS.1and2; the rotor punching sheet10includes a punching sheet body11, a shaft hole12, and a plurality of slot groups13, where the shaft hole12is provided on the punching sheet body11. The plurality of slot groups13are provided on the punching sheet body11, each slot group13includes at least one magnetic slot, each magnetic slot includes two magnet slots130, each magnet slot130includes a first slot end1311and a second slot end1312on an axial end face, and the first slot end1311is arranged closer to the shaft hole12than the second slot end1312. Herein, a peripheral edge of the punching sheet body11includes a peripheral section on the axial end face, the peripheral section includes a plurality of connected arc-shaped sections110corresponding to the plurality of slot groups13, each arc-shaped section110includes a first circular arc section111concentric with the shaft hole12and a second circular arc section112eccentric with the shaft hole12.

The rotor punching sheet10provided herein includes the punching sheet body11, the shaft hole12, and the plurality of slot groups13. The shaft hole12is provided on the punching sheet body11, and the punching sheet body11is made of magnetic steel. The shaft hole12is configured to fit the rotating shaft of the rotor. The plurality of slot groups13are arranged on the punching sheet body11about the shaft hole12. It is to be noted that all or some of a plurality of installations may have the same structure, which may be varied as appropriate. Each slot group13includes at least one magnetic slot, each magnetic slot includes two magnet slots130, and each magnet slot130is configured to install a permanent magnet of a rotor; each magnet slot130includes the first slot end1311and the second slot end1312on the axial end face, and the first slot end1311is arranged closer to the shaft hole12than the second slot end1312. When a distance between the first slot ends1311of the two magnet slots130and a distance between the second slot ends1312of the two magnet slots130are not equal, the two magnet slots130are arranged in a V-shape on the punching sheet body11. The openings of the two magnet slots130in the V-shaped arrangement are facing away from the shaft hole12. Further, the peripheral edge of the punching sheet body11includes the peripheral section on the axial end face, the peripheral section being a segment with definite endpoints. The outer peripheral section includes a plurality of connected arc-shaped sections110, one arc-shaped section110corresponding to one slot group13; it is to be noted that the number of the arc-shaped sections110and the number of the slot groups13are equal to the number of magnetic poles of the electric motor20. By configuring that each arc-shaped section110includes at least the first circular arc section111concentric with the shaft hole12and the second circular arc section112eccentric with the shaft hole12, an unequal air gap periodically varying along a circumferential direction can be formed between an outer circumference circle of the rotor and an inner circumference circle of the stator21for the electric motor20, and accordingly, a left arc section112a, the first circular arc section111, and then a right arc section112bcan alternate on an outer circumference circle of the rotor punching sheet10and then the operation of the electric motor20can be more stable. Moreover, the distribution of a magnetic field of the rotor is optimized, and a Q-axis and D-axis armature reaction is effectively weakened, which effectively addresses the problem of the torque pulsation of the electric motor20while keeping a peak torque of the electric motor20unchanged; as such, the vibration noise of the electric motor20in operation is reduced, rendering a better user experience. In addition, the stator21and the rotor of the electric motor20suffer from less iron loss, which is beneficial to improve the efficiency of the electric motor20. Furthermore, the combination of the first circular arc section111and the second circular arc section112takes into account the advantages of both a full-circle design and a completely eccentric design of the rotor punching sheet10. With an average length of the air gap of the electric motor20unchanged and the peak torque of the electric motor20unchanged, an air-gap magnetic field is effectively improved and then an air-gap magnetic density and a sinusoidal degree of a counter electromotive force waveform are increased; a proportion of harmonic waves is reduced, for reducing the torque pulsation, and significantly reducing the vibration noise of the electric motor20. In the present application, at least one V-shaped magnetic slot is correspondingly provided at each magnetic pole of the electric motor20, and each arc-shaped section110at least includes the concentric first circular arc section111and the eccentric second circular arc section112; as such, an overall structural layout of the rotor punching sheet10is more reasonable, and the distribution of the air-gap magnetic density of the electric motor20can be effectively improved on the basis of ensuring an output torque of the electric motor20, which reduces the proportion of harmonic waves for the electric motor20; accordingly, the problem of the torque pulsation and vibration noise of the electric motor20can be solved, and a design of an electric motor20with excellent performance can be achieved.

Further, the number of magnetic poles of the electric motor20is eight, and the number of the slot groups13is eight, each slot group13including two magnetic slots, each magnetic slot including two magnet slots130. That is, each slot group13includes four magnet slots130.

Furthermore, as shown inFIG.1, either of the two magnet slots130includes a straight slot section1313connected between the first slot end1311and the second slot end1312and closer to another of the two magnet slots130, the straight slot section1313includes a distal end away from the shaft hole12, lines connecting the distal ends of the two magnet slots130to a center of the shaft hole12, respectively, form a polar arc angle α, and a central angle of the first circular arc section111is β, and

In this embodiment, for the two magnet slots130in one magnetic slot, either of the magnet slots130includes two straight sections connected between the first slot end1311and the second slot end1312, with one of the two straight sections closer to the other magnet slot130being the straight slot section1313. That is to say, the two magnet slots130include a first magnet slot131and a second magnet slot132, where the first magnet slot131includes a straight slot section1313facing the second magnet slot132, the second magnet slot132includes a straight slot section1313facing the first magnet slot131, either straight slot section1313includes a distal end away from the shaft hole12, and an included angle formed by lines connecting the distal ends of the first magnet slot131and the second magnet slot132to the center of the shaft hole12, respectively, is the polar arc angle α.

Furthermore, a center of a circle on which the first circular arc section111is located coincides with the center of the shaft hole12, and the central angle β corresponding to the first circular arc section111refers to an included angle between lines connecting two endpoints of the first circular arc section111to the center of the shaft hole12, respectively. In some embodiments, a line connecting an endpoint of the first circular arc section111to the center of the shaft hole12is denoted as a first connection line, a line connecting the other endpoint of the first circular arc section111to the center of the shaft hole12is denoted as a second connection line, and an included angle between the first connection line and the second connection line is the central angle β.

Furthermore, a ratio of polar arc angle α to the central angle β has a great influence on the peak torque, torque pulsation and air-gap magnetic field of the electric motor20. When β/α is smaller, a waveform distortion rate of the air-gap magnetic field of the electric motor20is smaller, and the torque pulsation is lower, but the torque and power of the electric motor20are lower, too. When β/α is larger, the waveform distortion of the air-gap magnetic field is greater, and the torque pulsation of the electric motor20is higher. Therefore, a proper value of β/α plays an important role in the performance of the electric motor20. By defining β/α in the above range, optimization of many aspects such as the torque, torque pulsation, and air gap harmonic wave of the electric motor20can be achieved. Without changing the torque of the electric motor20, the proportion of the harmonic waves can be effectively reduced, and the problem of the torque pulsation can be addressed for the electric motor20. In some embodiments, the value of β/α may be 0.35, 0.40, 0.45, 0.50, 0.55, 0.60, 0.65, 0.70, 0.75, 0.80, 0.85, 0.90, 0.95, 1.0, etc.

Furthermore, in the two straight sections, one straight section that is away from the other magnet slot130is an outer slot section, and an avoidance slot wall is provided between the outer slot section and the first slot end1311and/or the second slot end1312; the permanent magnet is provided in the magnet slot130and may contact the avoidance slot wall, and the avoidance slot wall can technically avoid dimensional interference between the magnet slot130and the permanent magnet, thus reducing the difficulty in assembling the permanent magnet. It is to be noted that the avoidance slot wall is an arc-shaped wall. The arc-shaped wall may protrude toward the inside of the magnet slot130or the outside of the magnet slot130. It is to be noted that the number of the arc-shaped wall is two, and the two arc-shaped walls are provided on the outer slot section corresponding to both ends of the permanent magnet.

In another embodiment, furthermore, the number of the second circular arc section112is two, and the two second circular arc sections112are connected on both sides of the first circular arc section111, respectively.

In this embodiment, the two second circular arc sections112are connected on both sides of the first circular arc section111, respectively. In some embodiments, the two second circular arc sections112include the left arc section112aand the right arc section112b, that is, for one magnetic pole of the electric motor20, the arc-shaped sections110include the left arc section112a, the first circular arc section111, and a right arc section112bthat are connected in sequence. Considering adjacent magnetic poles, the left arc section112aof a magnetic pole is connected to the right arc section112bof an adjacent magnetic pole, and the right arc section112bof a magnetic pole is connected to the left arc section112aof an adjacent magnetic pole. Furthermore, a center of the second circular arc section112does not coincide with the center of the shaft hole12, that is to say, the peripheral edge of the punching sheet body11is formed by combining the first circular arc section111concentric with the center of the shaft hole12and the second circular arc section112eccentric with the center of the shaft hole12; therefore, an unequal air gap periodically varying along a circumferential direction can be formed between an outer circumference circle of the rotor and an inner circumference circle of the stator21for the electric motor20, and accordingly, the left arc section112a, the first circular arc section111, and then the right arc section112bcan alternate on an outer circumference circle of the rotor punching sheet10and then the operation of the electric motor20can be more stable. Moreover, the distribution of a magnetic field of the rotor is optimized, and a Q-axis and D-axis armature reaction is effectively weakened, which effectively addresses the problem of the torque pulsation of the electric motor20while keeping a peak torque of the electric motor20unchanged; as such, the vibration noise of the electric motor20in operation is reduced, rendering a better user experience. In addition, the stator21and the rotor of the electric motor20suffer from less iron loss, which is beneficial to improve the efficiency of the electric motor20. Furthermore, the combination of the first circular arc section111and the second circular arc section112takes into account the advantages of both a full-circle design and a completely eccentric design of the rotor punching sheet10. With an average length of the air gap of the electric motor20unchanged and the peak torque of the electric motor20unchanged, an air-gap magnetic field is effectively improved and then an air-gap magnetic density and a sinusoidal degree of a counter electromotive force waveform are increased; a proportion of harmonic waves is reduced, for reducing the torque pulsation, and significantly reducing the vibration noise of the electric motor20.

Furthermore, as shown inFIGS.1,2, and5, the second circular arc section112includes at least one eccentric circular arc section.

In this embodiment, each second circular arc section112includes at least one eccentric circular arc section. In the case that the second circular arc section112includes one eccentric circular arc section, the arc-shaped section110includes one first circular arc section111and two eccentric circular arc sections for one magnetic pole of the electric motor20. In the case that the second circular arc section112includes two eccentric circular arc sections, the arc-shaped section110includes one first circular arc section111and four eccentric circular arc sections for one magnetic pole of the electric motor20. That is to say, the number of the circular arc sections in the arc-shaped section110may be three, five, seven, etc. In the case of multiple eccentric circular arc sections, for one arc-shaped section110, multiple varying unequal air gaps can be formed between the outer circumference circle of the rotor of the rotor punching sheet10and the inner circumference circle of the stator21, which is beneficial to the stable operation of the electric motor20. Moreover, the distribution of the magnetic field of a rotor with the rotor punching sheet10is optimized, and the Q-axis and D-axis armature reaction is effectively weakened, which effectively addresses the problem of the torque pulsation of the electric motor while keeping the peak torque of the electric motor20unchanged; as such, the vibration noise of the electric motor20in operation is reduced, rendering a better user experience.

On the basis of the foregoing embodiment, the exemplary structure of each magnetic slot is described in this embodiment. Furthermore, as shown inFIGS.1,2,3,4, and5, the number of the at least one magnetic slot is two, the first slot ends1311of the two magnet slots130of each magnetic slot are close to each other, and the second slot ends1312of the two magnet slots130of each magnetic slot are away from each other; the two magnetic slots include a first magnetic slot1301and a second magnetic slot1302, where the first magnetic slot1301is arranged closer to the shaft hole12than the second magnetic slot1302, and the second magnetic slot1302forms the polar arc angle α; herein, the first magnetic slot1301and the second magnetic slot1302are symmetrical with respect to a center line N of a magnetic pole where they are located.

In this embodiment, for one magnetic pole of the electric motor20, the slot group13includes two magnetic slots, the first slot ends1311of the two magnet slots130in each magnetic slot are close to each other, and the second slot ends1312of the two magnet slots130in each magnetic slot are away from each other, that is, the two magnetic slots are both V-shaped slots, and slot openings of the V-shaped slots formed by the two magnet slots130in each magnetic slot all face the peripheral edge of the punching sheet body11, i.e., face away from the shaft hole12. Furthermore, the two magnetic slots include the first magnetic slot1301and the second magnetic slot1302, and the first magnetic slot1301is arranged closer to the shaft hole12than the second magnetic slot1302, that is, the first slot end1311of the magnet slot130in the second magnetic slot1302is arranged closer to the shaft hole12than the first slot end1311of the magnet slot130in the second magnetic slot1302. It is to be noted that in the case that the number of magnetic slots is two, the polar arc angle α mentioned in the foregoing embodiment refers to an angle formed by the two magnet slots130of the second magnetic slot1302. That is to say, the two magnet slots130of the second magnetic slot1302include the first magnet slot131and the second magnet slot132, the first magnet slot131includes the straight slot section1313facing the second magnet slot132, the second magnet slot132includes the straight slot section1313facing the first magnet slot131, either straight slot section1313includes a distal end away from the shaft hole12, and an included angle formed by lines connecting the distal ends of the first magnet slot131and the second magnet slot132to the center of the shaft hole12, respectively, is the polar arc angle α. Furthermore, the first magnetic slot1301and the second magnetic slot1302are symmetrical with respect to a center line of a magnetic pole where they are located and then the electric motor20having the rotor punching sheet10can be simply constructed, easily manufactured, and produced with low costs.

Furthermore, as shown inFIGS.3and5, an included angle formed by extension lines of the straight slot sections1313of the two magnet slots130in the first magnetic slot1301is a first opening angle, an included angle formed by the extension lines of the straight slot sections1313of the two magnet slots130in the second magnetic slot1302is a second opening angle, and the first opening angle is not equal to the second opening angle.

In this embodiment, the included angle formed by the extension lines of the straight slot sections1313of the two magnet slots130in the first magnetic slot1301is the first opening angle, the included angle formed by the extension lines of the straight slot sections1313of the two magnet slots130in the second magnetic slot1302is the second opening angle, and the first opening angle is not equal to the second opening angle; as such, the magnetic field strength of each magnetic pole is better increased for magnetism gathering, and a ratio of the Q-axis inductance to the D-axis inductance of the electric motor20is further increased with the increase the output torque of the electric motor20, for increasing a reluctance torque component, and improving a field-weakening speed expansion capability of the electric motor20. In some embodiments, the first opening angle is larger than the second opening angle, or the first opening angle is smaller than the second opening angle.

Furthermore, as shown inFIGS.3and5, the first opening angle is smaller than the second opening angle.

In this embodiment, the first opening angle of the first magnetic slot1301closer to the shaft hole12is smaller than the second opening angle of the second magnetic slot1302away from the shaft hole12; as such, the magnetic field strength of each magnetic pole is better increased for magnetism gathering, and the ratio of the Q-axis inductance to the D-axis inductance of the electric motor20is further increased with the increase the output torque of the electric motor20, for increasing the reluctance torque component, and improving the field-weakening speed expansion capability of the electric motor20.

On the basis of the foregoing embodiment, the arrangement and exemplary structure of the different arc-shaped sections in the arc-shaped section110are further described in this embodiment. As shown inFIGS.3and5, furthermore, the first circular arc section111is symmetrical with respect to the center line N of the magnetic pole where it is. The two second circular arc sections112are symmetrical with respect to the center line N of the magnetic pole where they are located.

In this embodiment, the first circular arc section111is symmetrical with respect to the center line of the magnetic pole where it is. The two second circular arc sections112are symmetrical with respect to the center line of the magnetic pole where they are located. That is to say, each arc-shaped section110is symmetrical with respect to the center line of the magnetic pole where it is and then a periodically varying unequal air gap is formed between the peripheral edge composed of a plurality of arc-shaped sections110of the whole punching sheet body11and the inner peripheral circle of the stator21. With an average length of the air gap of the electric motor20unchanged and the peak torque of the electric motor20unchanged, an air-gap magnetic field is effectively improved and then an air-gap magnetic density and a sinusoidal degree of a counter electromotive force waveform are increased; a proportion of harmonic waves is reduced, for reducing the torque pulsation, and significantly reducing the vibration noise of the electric motor20. In addition, by arranging the arc-shaped section110to be symmetrical with respect to the center line of the magnetic pole, the rotor punching sheet10is less difficult to be manufactured, and the product yield is improved.

Furthermore, lengths of the first circular arc sections111of the plurality of arc-shaped sections110are equal. Radiuses of circles on which the first circular arc sections111of the plurality of arc-shaped sections110are located are equal.

In this embodiment, the lengths of the first circular arc sections111of the plurality of arc-shaped sections110are equal, which can further ensure that there is a periodically varying unequal air gap between the outer circumference circle of the rotor and the inner circumference circle of the stator21. With the average length of the air gap of the electric motor20unchanged and the peak torque of the electric motor20unchanged, an air-gap magnetic field is effectively improved. Furthermore, the radiuses of the circles on which the first circular arc sections111of the plurality of arc-shaped sections110are located are all equal, that is, the plurality of first circular arc sections111are those on one circle. As such, a projection of a maximum outer contour of the rotor punching sheet10on the axial end face can be in a regular shape and then the space required for the rotor with the rotor punching sheet10during high-speed rotation is relatively regular, that is, in a cylindrical shape, which facilitates the machining preparation of the stator21adapted thereto. Furthermore, as shown inFIG.5, the center of the second circular arc section112is located on the punching sheet body11.

In this embodiment, the center of the second circular arc section112is on the punching sheet body11, that is, the second circular arc section112projects face away from the shaft hole12. In other words, the centers of the first circular arc section111and the second circular arc section112are both on the punching sheet body11, and the first circular arc section111and the second circular arc section112are bent in a similar trend and then it is more feasible to enable a periodically varying air gap between the outer circumference circle of the rotor and the inner circumference circle of the stator21along a circumference, for making the operation of the electric motor to be more stable. Moreover, the distribution of a magnetic field of the rotor is optimized, and a Q-axis and D-axis armature reaction is effectively weakened, which effectively addresses the problem of the torque pulsation of the electric motor20while keeping a peak torque of the electric motor20unchanged; as such, the vibration noise of the electric motor20in operation is reduced, rendering a better user experience.

On the basis of the foregoing embodiment, the exemplary structure of the slot group13is further described in this embodiment. As shown inFIGS.4and5, furthermore, the slot group13includes an auxiliary slot140provided on the peripheral edge of the punching sheet body11.

In this embodiment, each slot group13has the auxiliary slot140, and the auxiliary slot140is provided on the peripheral edge of the punching sheet body11. The auxiliary slot140can effectively reduce the proportion of harmonic waves in the air-gap magnetic field of the electric motor20to improve a sinusoidal degree of an air-gap magnetic density waveform, and address the problem of the torque pulsation of the electric motor20, which in turn can reduce a radial force caused by the harmonic wave, reduce the running noise of the electric motor20, and solve the problem of the vibration noise of the electric motor20, for rendering a better user experience. In addition, by providing concave auxiliary slots140on the rotor punching sheet10in the present application, it is also possible to partially adjust the no-load counter electromotive force waveform and radial force of the electric motor20, to reduce a maximum no-load line counter electromotive force of the electric motor20. It is to be noted that the torque pulsation of the electric motor20largely depends on a non-sinusoidal degree of the air-gap magnetic field, and a larger proportion of harmonic waves in the air-gap magnetic field leads to a worse output torque waveform of the electric motor20, in which case, the torque pulsation is higher, and the vibration noise is bigger.

Furthermore, as shown inFIG.5, the auxiliary slot140is provided in plurality, and the plurality of auxiliary slots140are arranged at intervals and are symmetrically arranged along the center line N of the magnetic pole where they are located.

In this embodiment, each slot group13includes a plurality of auxiliary slots140, in some embodiments, one slot group13may be provided with four auxiliary slots140, the plurality of auxiliary slots140being arranged at intervals on the punching sheet body11. The plurality of auxiliary slots140of one slot group13are arranged symmetrically along the center line of the magnetic pole, and at least two auxiliary slots140are provided and arranged in pairs.

Furthermore, as shown inFIG.5, the auxiliary slot140is an arc-shaped slot, in some embodiments, a slot bottom of the auxiliary slot140is a circular arc bottom.

Furthermore, the auxiliary slots140include two first auxiliary slots141, and the two first auxiliary slots141are arranged symmetrically on the first circular arc section111along the center line of the magnetic pole where they are located. Furthermore, the auxiliary slots include two second auxiliary slots142, and the two second auxiliary slots142are respectively provided on two second circular arc sections112symmetrically along the center line of the magnetic pole where they are located.

In this embodiment, the auxiliary slots140include two first auxiliary slots141and two second auxiliary slots142, where the two first auxiliary slots141are symmetrically arranged on the first circular arc section111along the center line of the magnetic pole, the two second auxiliary slots142are arranged on the second circular arc section112along the center line of the magnetic pole, and the two second auxiliary slots142are arranged on two different arc-shaped sections, respectively.

Furthermore, a slot depth of the first auxiliary slot141is greater than a slot depth of the second auxiliary slot142, that is, in the case of the concentric first circular arc section111, the slot depth of the first auxiliary slot141is greater, and in the case of the eccentric second circular arc section112, the slot depth of the second auxiliary slot142is smaller; through the combination of the first auxiliary slot141and the second auxiliary slot142with different slot depths, it is possible to further reduce the proportion of harmonic waves in the air-gap magnetic field, for improving the sinusoidal degree of the air-gap magnetic density waveform, and addressing the problem of the torque pulsation and the radial force; moreover, the arrangement of the auxiliary slots140can also partially adjust the no-load counter electromotive force waveform, to reduce the amplitude of the maximum no-load line counter electromotive force of the electric motor20.

It is to be noted that the two first auxiliary slots141are sized the same, and the two second auxiliary slots142are sized the same. In some embodiments, the two first auxiliary slots141close to the center line of the magnetic pole can effectively optimize the waveform of the air-gap magnetic density, and improve the sinusoidal degree of the thin air-gap magnetic field, which in turn can reduce the radial electromagnetic force density of the electric motor20, optimize the torque waveform of the electric motor20, and reduce the torque pulsation. The two second auxiliary slots142away from the center line of the magnetic pole, with respect to the first auxiliary slots141, can reduce the maximum no-load line counter electromotive force of the electric motor20while reducing the torque pulsation of the electric motor20and keeping the peak torque of the electric motor20unchanged.

In an embodiment, furthermore, the auxiliary slot140may include only the first auxiliary slot141, that is, two first auxiliary slots141are provided at positions corresponding to the first circular arc section111, not including the second auxiliary slot142provided on the second circular arc section112.

Furthermore, the first auxiliary slot141has a slot depth of 0.5 mm or more and 0.9 mm or less. In addition/in some embodiments, the slot depth of the second auxiliary slot142is 0.1 mm or more and 0.7 mm or less.

In this embodiment, the slot depth of the first auxiliary slot141falls within the above range, in some embodiments, the slot depth of the first auxiliary slot141may be 0.5 mm, 0.55 mm, 0.60 mm, 0.65 mm, 0.70 mm, 0.75 mm, 0.80 mm, 0.85 mm, 0.90 mm, etc. The slot depth of the second auxiliary slot142falls within the above range, in some embodiments, the slot depth of the second auxiliary slot142may be 0.1 mm, 0.15 mm, 0.20 mm, 0.25 mm, 0.30 mm, 0.35 mm, 0.40 mm, 0.45 mm, 0.5 mm, 0.55 mm, 0.6 mm, 0.65 mm, 0.7 mm, etc. When the slot depths of the first auxiliary slot141and the second auxiliary slot142fall within the range defined above, a small volume of the auxiliary slot140can be ensured with the performance of the electric motor20effectively improved by the auxiliary slot140, preventing the auxiliary slot140from causing a large change in the shape of the peripheral edge of the punching sheet body11.

According to a second aspect of the present application, a rotor iron core is provided, including the rotor punching sheet10provided by any of the above embodiments, where the rotor punching sheet10is provided in plurality, the plurality of rotor punching sheets10are stacked, and the plurality of slot groups13of the plurality of rotor punching sheets10are axially aligned to form a plurality of insertion slots.

The rotor iron core provided by the present application includes the rotor punching sheet10provided by any of the above embodiments, and thus has all the advantageous effects of the rotor punching sheet10, which will not be described in detail herein.

It is to be noted that the rotor punching sheet10provided herein includes the punching sheet body11, the shaft hole12, and the plurality of slot groups13. The shaft hole12is provided on the punching sheet body11, and the punching sheet body11is made of magnetic steel. The shaft hole12is configured to fit the rotating shaft of the rotor. The plurality of slot groups13are arranged on the punching sheet body11about the shaft hole12. It is to be noted that all or some of a plurality of installations may have the same structure, which may be varied as appropriate. Each slot group13includes at least one magnetic slot, each magnetic slot includes two magnet slots130, and each magnet slot130is configured to install a permanent magnet of a rotor; each magnet slot130includes the first slot end1311and the second slot end1312on the axial end face, and the first slot end1311is arranged closer to the shaft hole12than the second slot end1312. When a distance between the first slot ends1311of the two magnet slots130and a distance between the second slot ends1312of the two magnet slots130are not equal, the two magnet slots130are arranged in a V-shape on the punching sheet body11. The openings of the two magnet slots130in the V-shaped arrangement are facing away from the shaft hole12. Further, the peripheral edge of the punching sheet body11includes the peripheral section on the axial end face, the peripheral section being a segment with definite endpoints. The outer peripheral section includes a plurality of connected arc-shaped sections110, one arc-shaped section110corresponding to one slot group13; it is to be noted that the number of the arc-shaped sections110and the number of the slot groups13are equal to the number of magnetic poles of the electric motor20. By configuring that each arc-shaped section110includes at least the first circular arc section111concentric with the shaft hole12, it is possible to make the air gap of the electric motor20at a position corresponding to the first circular arc section111to be uniform and then the air-gap magnetic density is improved, which avoids a large average air gap due to the outer peripheral section consisting of a completely eccentric circle, significant reduction of the torque and the power of the electric motor20, and insufficient output of the electric motor20. In the present application, at least one V-shaped magnetic slot is correspondingly provided at each magnetic pole of the electric motor20, and each arc-shaped section110at least includes the concentric first circular arc section111; as such, an overall structural layout of the rotor punching sheet10is more reasonable, which can reduce the production cost of the electric motor20, effectively improve the average air gap of the electric motor20, and increase the power density of the motor20on the basis of ensuring an output torque of the electric motor20; accordingly, the problem of the torque pulsation of the electric motor20can be solved, and a design of an electric motor20with excellent performance and low costs can be achieved.

For the two magnet slots130in one magnetic slot, either of the magnet slots130includes two straight sections connected between the first slot end1311and the second slot end1312, with one of the two straight sections closer to the other magnet slot130being the straight slot section1313. That is to say, the two magnet slots130include a first magnet slot131and a second magnet slot132, where the first magnet slot131includes a straight slot section1313facing the second magnet slot132, the second magnet slot132includes a straight slot section1313facing the first magnet slot131, either straight slot section1313includes a distal end away from the shaft hole12, and an included angle formed by lines connecting the distal ends of the first magnet slot131and the second magnet slot132to the center of the shaft hole12, respectively, is the polar arc angle α.

Furthermore, a center of a circle on which the first circular arc section111is located coincides with the center of the shaft hole12, and the central angle β corresponding to the first circular arc section111refers to an included angle between lines connecting two endpoints of the first circular arc section111to the center of the shaft hole12, respectively. In some embodiments, a line connecting an endpoint of the first circular arc section111to the center of the shaft hole12is denoted as a first connection line, a line connecting the other endpoint of the first circular arc section111to the center of the shaft hole12is denoted as a second connection line, and an included angle between the first connection line and the second connection line is the central angle θ.

Furthermore, a ratio of polar arc angle α to the central angle β has a great influence on the peak torque, torque pulsation and air-gap magnetic field of the electric motor20. When β/α is smaller, a waveform distortion rate of the air-gap magnetic field of the electric motor20is smaller, and the torque pulsation is lower, but the torque and power of the electric motor20are lower, too. When β/α is larger, the waveform distortion of the air-gap magnetic field is greater, and the torque pulsation of the electric motor20is higher. Therefore, a proper value of β/α plays an important role in the performance of the electric motor20. By defining β/α in the above range, optimization of many aspects such as the torque, torque pulsation, and air gap harmonic wave of the electric motor20can be achieved. Without changing the torque of the electric motor20, the proportion of the harmonic waves can be effectively reduced, and the problem of the torque pulsation can be addressed for the electric motor20.

Furthermore, the arc-shaped sections110include two second circular arc sections112, and the two second circular arc sections112are connected on both sides of the first circular arc section111, respectively. In some embodiments, the two second circular arc sections112include the left arc section112aand the right arc section112b, that is, for one magnetic pole of the electric motor20, the arc-shaped sections110include the left arc section112a, the first circular arc section111, and a right arc section112bthat are connected in sequence. Considering adjacent magnetic poles, the left arc section112aof a magnetic pole is connected to the right arc section112bof an adjacent magnetic pole, and the right arc section112bof a magnetic pole is connected to the left arc section112aof an adjacent magnetic pole. Furthermore, a center of the second circular arc section112does not coincide with the center of the shaft hole12, that is to say, the peripheral edge of the punching sheet body11is formed by combining the first circular arc section111concentric with the center of the shaft hole12and the second circular arc section112eccentric with the center of the shaft hole12; therefore, an unequal air gap periodically varying along a circumferential direction can be formed between an outer circumference circle of the rotor and an inner circumference circle of the stator21for the electric motor20, and accordingly, the left arc section112a, the first circular arc section111, and then the right arc section112bcan alternate on an outer circumference circle of the rotor punching sheet10and then the operation of the electric motor20can be more stable. Moreover, the distribution of a magnetic field of the rotor is optimized, and a Q-axis and D-axis armature reaction is effectively weakened, which effectively addresses the problem of the torque pulsation of the electric motor20while keeping a peak torque of the electric motor20unchanged; as such, the vibration noise of the electric motor20in operation is reduced, providing a better user experience. In addition, the stator21and the rotor of the electric motor20suffer from less iron loss, which is beneficial to improve the efficiency of the electric motor20. Furthermore, the combination of the first circular arc section111and the second circular arc section112takes into account the advantages of both a full-circle design and a completely eccentric design of the rotor punching sheet10. With an average length of the air gap of the electric motor20unchanged and the peak torque of the electric motor20unchanged, an air-gap magnetic field is effectively improved and then an air-gap magnetic density and a sinusoidal degree of a counter electromotive force waveform are increased; a proportion of harmonic waves is reduced, for reducing the torque pulsation, and significantly reducing the vibration noise of the electric motor20.

According to a third aspect of the present application, a rotor is provided, including the rotor iron core provided by any of the above embodiments, where the rotor further includes a plurality of permanent magnets, each of the plurality of permanent magnets being inserted in the plurality of insertion slots.

The rotor provided by the present application includes the rotor iron core provided by any of the above embodiments, and thus has all the advantageous effects of the rotor iron core, which will not be described in detail herein.

According to a fourth aspect of the present application, an electric motor20is provided, including the rotor provided by any of the above embodiments, where the electric motor20further includes a stator21, the stator21including a mounting cavity extending axially therethrough, the rotor being located within the mounting cavity.

The electric motor20provided by the present application includes the rotor provided by any of the above embodiments, and thus has all the advantageous effects of the rotor, which will not be described in detail herein.

In some embodiments, the rotor punching sheet10in the rotor includes the punching sheet body11, the shaft hole12provided on the punching sheet body11, and a plurality of slot groups13. The plurality of slot groups13are provided on the punching sheet body11, each slot group13includes at least one magnetic slot, each magnetic slot includes two magnet slots130, each magnet slot130includes a first slot end1311and a second slot end1312on an axial end face, and the first slot end1311is arranged closer to the shaft hole12than the second slot end1312. Herein, a peripheral edge of the punching sheet body11includes a peripheral section on the axial end face, the peripheral section includes a plurality of connected arc-shaped sections110corresponding to the plurality of slot groups13, each arc-shaped section110includes a first circular arc section111concentric with the shaft hole12Furthermore, either of the two magnet slots130includes a straight slot section1313connected between the first slot end1311and the second slot end1312and closer to another of the two magnet slots130, the straight slot section1313includes a distal end away from the shaft hole12, lines connecting the distal ends of the two magnet slots130to a center of the shaft hole12, respectively, form a polar arc angle α, and a central angle of the first circular arc section111is β, and

Furthermore, the arc-shaped sections110include two second circular arc sections112, and the two second circular arc sections112are connected on both sides of the first circular arc section111, respectively. The center of the second circular arc section112does not coincide with the center of the shaft hole12. The present application takes into account the advantages of both a full-circle design and a completely eccentric design of the rotor punching sheet10. With an average length of the air gap of the electric motor20unchanged and the peak torque of the electric motor20unchanged, an air-gap magnetic field is effectively improved and then an air-gap magnetic density and a sinusoidal degree of a counter electromotive force waveform are increased; a proportion of harmonic waves is reduced, for reducing the torque pulsation, and significantly reducing the vibration noise of the electric motor20. The full circle design of the rotor punching sheet10means that the outer peripheral section of the punching sheet body11of the rotor punching sheet10is a full circle. The completely eccentric design of the rotor punching sheet10means that the outer peripheral section of the punching sheet body11of the rotor punching sheet10includes a plurality of connected circular arc sections, and the center of the circle on which each circular arc section is located does not coincide with the center of the shaft hole12.

Furthermore, as shown inFIG.5, a minimum spacing between an outer peripheral wall of the rotor and an inner peripheral wall of the stator21is H1, and a maximum spacing between the outer peripheral wall of the rotor and the inner peripheral wall of the stator21is H2, where 0.15 mm≤H2−H1≤0.35 mm.

In this embodiment, the minimum spacing between the outer peripheral wall of the rotor and the inner peripheral wall of the stator21is H1. In some embodiments, there is a minimum spacing H1 between a point on the first circular arc section111of the rotor punching sheet10and the inner peripheral wall of the stator21, because as shown inFIG.4, the radius of the circle on which the first circular arc section111of the rotor punching sheet10is located is larger, that is, a distance L1 between a point on the first circular arc section111and the center of the shaft hole12is larger. The maximum distance between the peripheral wall of the rotor and the inner peripheral wall of the stator21is H2. In some embodiments, there is a maximum distance between a point on the second circular arc section112of the rotor punching sheet10and the inner peripheral wall of the stator21, because a distance L2 between a point on the second circular arc section112of the rotor punching sheet10and the center of the shaft hole12is smaller, that is, L2 is smaller than L1. Given that a radius of a projection of the inner peripheral wall of the stator21on the axial end face is R (i.e., a radius of an inner circle of the stator21), then the minimum spacing H1=R−L1, and the maximum spacing H2=R−L2, hence H2 is greater than H1.

In some embodiments, a difference between H1 and H2 not only directly determines an equivalent air gap length of the electric motor20and affects the air-gap magnetic field distribution, but also directly determines a salient pole ratio of the electric motor20and affects the peak torque and high-speed performance of the electric motor20. In some embodiments, the torque pulsation of the electric motor20mainly depends on the 5th, 7th, 11thand 13thharmonic waves of the air-gap magnetic field. In the case of a larger difference between H1 and H2, the air-gap magnetic field waveform is more sinusoidal, a harmonic wave amplitude of the electric motor20is smaller, and the torque pulsation is lower, but the peak torque of the electric motor20is also lower. The peak torque of the electric motor20consists of the reluctance torque component and a permanent magnet torque component, where the permanent magnet torque of the electric motor20is proportional to an amount of the permanent magnet, and the reluctance torque is proportional to the saliency ratio. Herein, the saliency ratio is a ratio of the Q-axis inductance to the D-axis inductance and is directly related to the difference between H1 and H2. Under the condition that the amount of the permanent magnet is constant, a proper distribution of the difference between H1 and H2 ensures that the equivalent air gap length of the electric motor20keeps unchanged and the salient ratio of the electric motor20does not change, for ensuring that the peak torque of the electric motor20does not change. Therefore, a solution allowing for a smaller proportion of harmonic waves, a lower torque pulsation, and better electromagnetic performance can be achieved under the same peak torque. In some embodiments, the value of H2−H1 may be 0.15 mm, 0.20 mm, 0.25 mm, 0.30 mm, 0.35 mm, etc.

Furthermore, as shown inFIGS.1,4and5, the number of magnetic poles of the electric motor20is P, a maximum distance between the center of the shaft hole12in the rotor punching sheet10of the electric motor20and the peripheral edge of the punching sheet body11is L1, a minimum distance between the center of the shaft hole12and the peripheral edge of the punching sheet body11is L2, and a radius of an arc where the center of the second circular arc section112of the rotor punching sheet10is located is r, where r satisfies the following equation:

In this embodiment, the number of magnetic poles of the electric motor20is P, the maximum distance between the center of the shaft hole12in the rotor punching sheet10of the electric motor20and the peripheral edge of the punching sheet body11is L1, the minimum distance between the center of the shaft hole12and the peripheral edge of the punching sheet body11is L2, and the radius of the arc where the center of the second circular arc section112of the rotor punching sheet10is located is r, where r satisfies the above equation. As such, the center of the eccentric circular arc section in the second circular arc section112is located in the circle taking the center of the shaft hole12as the center and r as the radius. The center of the second circular arc section112cannot coincide with the center of the shaft hole12. By defining a position of the center of the eccentric circular arc section, the combination of the concentric first circular arc section111and the eccentric second circular arc section112is thus more reasonable, and takes into account the advantages of both a full-circle design and a completely eccentric design of the rotor punching sheet10. With an average length of the air gap of the electric motor unchanged and the peak torque of the electric motor unchanged, an air-gap magnetic field is effectively improved and then an air-gap magnetic density and a sinusoidal degree of a counter electromotive force waveform are increased; a proportion of harmonic waves is reduced, for reducing the torque pulsation, and significantly reducing the vibration noise of the electric motor.

In an exemplary embodiment, taking an 8-pole 48-slot electric motor20as an example, the rotor punching sheet10includes two first auxiliary slots141and two second auxiliary slots142, and the magnetic slots include the first magnetic slot1301and the second magnetic slot1302arranged in a V-shape; once a value of a is determined, taking α=16° in this example, and under the condition that other parameters of the electric motor20are unchanged, the value taken for β/α may be 0.05, 0.15, 0.25, 0.35, 0.45, 0.55, 0.65, 0.75, 0.85, 0.95, 1.05, 1.15, and 1.25. As shown inFIG.6, curves of the average peak torque and torque pulsation rate of the electric motor20as a function of β/α are given, and it can be seen that when the value of β/α is in the range from 0.35 to 1, the peak torque and torque pulsation rate of the electric motor20are both at an optimal level.

In addition, under the same condition of keeping other parameters of the electric motor20unchanged, a difference between H1 and H2 is changed, where H2=0.65 mm is taken, and the difference between H1 and H2 is 0.05 mm, 0.15 mm, 0.25 mm, 0.35 mm, 0.45 mm and 0.55 mm. InFIG.7, curves of the average peak torque and the torque pulsation rate as a function of the difference between H2 and H1 are shown, and it can be seen that when the value of H2−H1 is in the range from 0.15 mm to 0.35 mm, the peak torque and the torque pulsation rate of the electric motor20are both at an optimal level.

Furthermore, in the case that the ratio of β to α satisfies 0.35≤β/α<1 and the difference between H2 and H1 ranges from 0.15 mm to 0.35 mm, a combination of β, H1, and H2 is reasonably selected within the range. In some embodiments, the parameters are given as follows: α=16°, β=13°, H1=0.7 mm, and H2=0.9 mm, and Table 1 below is a table of electromagnetic parameters of the electric motor20at the peak torque point. It can be seen from Table 1 that, compared with the full-circle design of the rotor, the technical means of the present application reduces the waveform distortion rate of the air-gap magnetic density of the electric motor20without changing the average air gap length of the electric motor20or changing the peak torque of the electric motor20, which lowers the torque pulsation of the electric motor20, for effectively improving the torque performance and solving the problem of the vibration noise for the electric motor20.

FIG.8is a graph of the torque pulsation distribution for the electric motor20at full speed in the conventional full-circle design, andFIG.9is a graph of the torque pulsation distribution for the electric motor20at full speed in the present application. It can be seen from the comparison that the torque pulsation at full speed decreases, where the torque pulsation at 8000 rpm to 16000 rpm decreases significantly, with a maximum decrease of 87.5%, and thus the torque pulsation at high speed is controlled under 8.5%.

According to a fifth aspect of the present application, a vehicle is provided, including the electric motor20provided by any of the above embodiments.

The vehicle provided by the present application includes the electric motor20provided by any of the above embodiments, and thus has all the advantageous effects of the electric motor20, which will not be described in detail herein.

It is to be noted that the vehicle may be a new energy vehicle. New energy vehicles include pure electric vehicles, extended-range electric vehicles, hybrid electric vehicles, fuel cell electric vehicles, hydrogen engine vehicles, etc. Furthermore, the electric motor20provided by any of the above embodiments may be used as a drive electric motor for the vehicle. In some embodiments, the drive electric motor20alone can start functional devices of the vehicle. In some embodiments, the drive electric motor20may cooperate with other drive devices on the vehicle to achieve proper operation of functional devices on the vehicle. Herein, the functional device of the vehicle may be any one or any combination of a wheel, an air conditioner, a light assembly, and others.

In this disclosure, the term “plurality” refers to two or more than two unless explicitly defined otherwise. The terms like “mounted”, “connected”, “coupled”, and “fixed” are to be construed broadly, e.g., being “connected” may be through a fixed connection, a detachable connection, or an integral connection; being “coupled” may be either directly coupled or indirectly coupled through an intermediary. For a person of ordinary skill in the art, the specific meaning of the above terms in the present application can be understood according to specific situations.

In the description, references to “an embodiment”, “some embodiments”, “exemplary embodiments”, and the like, mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present application. In this description, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

While the foregoing is directed to the preferred embodiments of the present application, other and further embodiments of the present disclosure may be devised without departing from the basic scope thereof, and the scope thereof is defined by the appended claims. All changes, equivalents, improvements, and the like, which come within the spirit and scope of the present disclosure are intended to be embraced therein.