Electric motor, electric drive system and vehicle

Abstract

The present disclosure provides an electric motor, comprising: a stator, which is provided with multiple stator teeth and multiple stator slots separated by the multiple stator teeth; and a rotor, which is rotatably arranged inside the stator. The rotor comprises: a rotor shaft, which has an extension axis; and a rotor main body, which is formed by stacking multiple laminations and is capable of rotating around the extension axis, wherein a magnet mounting slot is provided in each of the multiple laminations; a subsequent lamination in the multiple laminations deviates by a first angle along a first deviation direction with respect to a previous lamination, the first deviation direction being perpendicular to the extension axis, and sidewalls of the magnet mounting slots in the respective multiple laminations are slanted at the same second angle to form a smooth magnet mounting cavity of the rotor main body.

Description

[0001] ELECTRIC MOTOR, ELECTRIC DRIVE SYSTEM AND VEHICLE

[0002] TECHNICAL FIELD

[0003] The present disclosure relates to an electric motor, an electric drive system and a vehicle.

[0004] BACKGROUND

[0005] The electric motor is mainly composed of a stator and a rotor; the rotor is formed by stacking multiple iron cores, and the rotor cores are internally provided with magnet mounting holes in which permanent magnets are inserted. As the rotor rotates, a magnetic flux distribution density in a gap between the stator and the rotor is not smooth, creating torque pulsations in the rotor such as cogging torque and torque fluctuations, which in turn produces vibration and noise. In a known technical solution, the rotor cores are staggered in a circumferential direction, forming multi-step inclined slots in the rotor, so that the permanent magnets are placed in a skewed relationship, so as to reduce the torque pulsation mentioned above. However, this misalignment affects potting efficiency and requires a certain amount of pressure to inject potting material into the gaps between the permanent magnets and the magnet mounting holes. In addition, the inefficient potting process in the above solution affects the dynamic balance of the rotor. In this design, the rotor requires an end plate to reduce weight for improved dynamic balance, and the end plate is recessed to improve the potting process; however, this creates problems such as complex system structures and higher costs.

[0006] Thus, there is a need in the art for an electric motor capable of solving the abovementioned problem.

[0007] SUMMARY OF THE INVENTION

[0008] Therefore, an object of the present disclosure is to provide an electric motor, an electric drive system and a vehicle, wherein a rotor of the electric motor comprises an inclined smooth magnet mounting cavity, which runs straight from one end of the rotor through to the other end, so that no end plate is required, the i potting process does not need to be performed under pressure, and the dynamic balance is improved.

[0009] The abovementioned object is achieved through the electric motor, the electric drive system and the vehicle which are described below.

[0010] The present disclosure provides an electric motor, the electric motor comprising: a stator, which is provided with multiple stator teeth and multiple stator slots separated by the multiple stator teeth; and a rotor, which is rotatably arranged inside the stator, wherein the rotor comprises: a rotor shaft, which has an extension axis; and a rotor main body, which is formed by stacking multiple laminations and is capable of rotating around the extension axis, wherein a magnet mounting slot is provided in each of the multiple laminations; a subsequent lamination in the multiple laminations deviates by a first angle along a first deviation direction with respect to a previous lamination, the first deviation direction being perpendicular to the extension axis, and sidewalls of the magnet mounting slots in the respective multiple laminations are slanted at the same second angle to form a smooth magnet mounting cavity of the rotor main body.

[0011] By the above means, a common permanent magnet of a whole regular cuboid shape may be inserted without obstruction from one end of the rotor main body into the smooth magnet mounting cavity, and is arranged in a skewed manner with respect to the extension axis. In this way, not only can a skewed arrangement of a magnet be achieved, but also there is no need for a specially shaped magnet or for split pieces of magnets.

[0012] In one embodiment, a total angle of deviation of a first lamination with respect to a last lamination in the multiple laminations is equal to an angular spacing between two stator teeth that are adjacent. In this way, vibration and noise from cogging torque can be significantly reduced.

[0013] In one embodiment, the first angle is equal to the total angle divided by the number of laminations.

[0014] In one embodiment, the total angle is 6 degrees to 9 degrees.

[0015] In one embodiment, the second angle may be equal to the angular spacing between two stator teeth that are adjacent. In one embodiment, the rotor further comprises interlocking parts, and the interlocking parts are respectively arranged on contact surfaces of the laminations and are distributed in a circumferential direction centred on the extension axis.

[0016] In one embodiment, the interlocking part comprises a protrusion arranged on a contact surface of a lamination of adjacent laminations and a slot on a contact surface of the other lamination, and the protrusion is joined to the slot in an interference fit.

[0017] Such a manner of assembly can achieve secure mounting, and is simple in structure and easy to achieve.

[0018] In one embodiment, an inlet of the magnet mounting slot is provided with a rounded edge. This can facilitate the flow of potting into the magnet mounting slot, and further promotes performance of the potting process.

[0019] In one embodiment, a gap is formed between an inner wall of the magnet mounting slot and a magnet, and the gap runs unobstructed from one end of the rotor main body through to another end. Since the gap also runs from one end of the rotor main body through to the other end, a potting process does not need to be performed under pressure, and it is not necessary to provide end plates at both ends of the rotor main body, and the dynamic balance is improved.

[0020] The present disclosure further provides an electric drive system, wherein the electric drive system comprises the electric motor described above.

[0021] The present disclosure further provides a vehicle, the vehicle comprising the electric motor described above, or comprising the electric drive system described above.

[0022] Embodiments of the present disclosure have the following advantages: the rotor of the electric motor of the present disclosure can realize an inclined smooth magnet mounting cavity, which runs straight from one end of the rotor through to the other end, so that a complex or specially shaped magnet is not needed, the potting process does not need to be performed under pressure, and it is not necessary to provide end plates at both ends of the rotor main body, and the dynamic balance is improved. The rotor of the electric motor is structurally simple and low in cost, and can significantly reduce vibration and noise, and has high reliability.

[0023] BRIEF DESCRIPTION OF THE DRAWINGS

[0024] A better understanding of the advantages and objective of the present disclosure can be gained from the preferred embodiments of the present disclosure described in detail below with reference to the drawings. To better illustrate the relationships among components in the drawings, the drawings are not drawn to scale. In the drawings:

[0025] Fig. 1 shows a schematic drawing of a rotor of an electric motor of an electric drive system of a vehicle according to an embodiment of the present disclosure;

[0026] Fig. 2 shows a perspective view of a rotor of an electric motor according to an embodiment of the present disclosure;

[0027] Fig. 3 shows a schematic drawing of a lamination of the rotor according to Fig. 1;

[0028] Fig. 4 shows a schematic drawing of another lamination of the rotor according to Fig. 1;

[0029] Fig. 5 shows a superimposed schematic drawing of laminations of two ends of the rotor according to Fig. 1;

[0030] Fig. 6 shows a cross-sectional view of a part of an electric motor according to an embodiment of the present disclosure; and

[0031] Fig. 7 shows a partial schematic drawing of the rotor according to Fig. 1.

[0032] DESCRIPTION OF THE EMBODIMENTS

[0033] In order to clarify the technical solution objective, the technical solution and advantages of the present disclosure, the technical solution of embodiments of the present disclosure is described clearly and completely below in conjunction with the drawings accompanying particular embodiments of the present disclosure. In the drawings, identical reference numerals denote identical components. It must be explained that the embodiments described are some, not all, of the embodiments of the present disclosure. All other embodiments obtained by those skilled in the art based on the described embodiments of the present disclosure without the need for inventive effort shall fall within the scope of protection of the present disclosure.

[0034] Unless otherwise defined, the technical or scientific terms used herein shall have the common meanings understood by those skilled in the art. The words "first", "second", and the like used in the description and claims of the patent application disclosed herein do not indicate any order, quantity or importance, being merely used to distinguish different component parts. Likewise, words such as "a" or "one" do not necessarily represent a quantity limit. Words such as "comprising", "including" or "having" mean that the element or object preceding the word covers the elements or objects and equivalents thereof listed after the word, without excluding other elements or objects. Words such as "connection" or "communication", rather than being limited to the physical or mechanical connection or communication shown in a drawing, may include connection or communication equivalent thereto, irrespective of whether it is direct or indirect. "Upper", "lower", "left", "right", etc. are only used to indicate a relative positional relationship, and when the absolute position of a described object changes, the relative positional relationship may also change accordingly.

[0035] Embodiments of the present disclosure are described in detail below with reference to Figs. 1 - 7.

[0036] An electric motor according to the present disclosure may comprise a stator 15 and a rotor 17 as shown in Fig. 1; the rotor and the stator are both sealed in a housing of the electric motor, and the rotor 17 is rotatably arranged inside the stator 15, as shown in the sectional view in Fig. 6. The rotor 17 comprises a rotor shaft (not shown) with an extension axis A and a rotor main body 1 ; the rotor main body 1 is formed by stacking multiple laminations 2 and is capable of rotating around the extension axis A. The rotor shaft extends through a hole in the centre of the rotor main body 1 and is rotatably supported on the housing of the electric motor by means of a bearing; the rotor main body 1 is fixed to and rotates with the rotor shaft. The lamination 2 is for example a silicon steel plate. A magnet mounting slot 3 is arranged in each of the multiple laminations 2, and is provided with a permanent magnet or magnetic steel. The stator 15 also comprises a stator core formed by multiple metal laminations (e.g., silicon steel plates), and is provided with multiple stator teeth 18 and multiple stator slots 16 separated by the stator teeth, as shown in Fig. 6, and a winding is wound through the stator slots. The stator core has a roughly tubular structure, with the rotor accommodated therein. As shown in Fig. 6, the multiple stator teeth 18 are distributed at a distance apart from each other in a circumferential direction centred on the extension axis A, and extend along the extension axis A, and said distance is an angular spacing D between two stator teeth 18 that are adjacent. As an example, windings are able to generate a rotating magnetic field when supplied with three-phase alternating current, thereby generating electromagnetic torque to drive the rotor to rotate. The electric motor may be arranged in a vehicle or in an electric drive system of a vehicle. The vehicle may be an electrified vehicle, such as a pure electric vehicle, a hybrid vehicle, a plug-in hybrid vehicle, a range extended electric vehicle or a hydrogen vehicle.

[0037] As indicated by the slanted straight lines on the surface of the rotor main body 1 in Fig. 1 , a subsequent lamination in the multiple laminations 2 deviates by a first angle along a first deviation direction B with respect to a previous lamination. The first deviation direction B is perpendicular to the extension axis A, for example being the anti-clockwise direction of the right end of the rotor main body shown in Fig. 1, the specific direction depending on the viewing position. The first deviation direction B may also be called a circumferential direction of the rotor main body centred on the extension axis A. It should be noted that the slanted lines on the surface of the rotor main body 1 shown in Fig. 1 do not represent actual lines, but merely schematically illustrate the staggered arrangement of the multiple laminations and the extension direction of the sidewalls of the magnet mounting cavities.

[0038] Sidewalls of the magnet mounting slots 3 in the respective multiple laminations 2 are slanted at the same second angle 0 to form a smooth magnet mounting cavity of the rotor main body 1. The second angle 0 is described with respect to the extension axis A shown in Fig. 1 as a dotted line. The second angle P is in a different plane to the first angle described above. For example, the second angle 0 may be equal to the angular spacing D between two stator teeth 18 that are adjacent. The second angle 0 is also known as an inclined slot angle, and may be used to reduce harmonic components, reduce electric motor temperature rise, improve electric motor starting performance, reduce noise and vibration, as well as reduce effects of higher-order harmonic magnetic fields. The lamination of the present disclosure is rotated by the first angle in the circumferential direction of the rotor main body, and the magnet mounting slot in each lamination is inclined at the second angle with respect to the extension axis of the rotor shaft; these two measures ultimately obtain a smooth magnet mounting cavity that runs straight from one end of the rotor main body through to the other end.

[0039] Fig. 2 shows a perspective view of the rotor main body in Fig. 1, wherein the top lamination is the lamination of the right end in Fig. 1, and the bottom lamination is the lamination of the left end in Fig. 1. Fig. 3 shows the lamination of the right end in Fig. 1, and Fig. 4 shows another lamination that contacts said lamination. As shown in Figs. 2 to 3, the magnet mounting slots 3 on the lamination of the right end in Fig. 1 comprise mounting slots 5 and 6, wherein the mounting slot 5 is comparatively closer to the centre of the rotor main body, and multiple groups of mounting slots 5 and 6 are symmetrically provided in regions partitioned along dotted lines. As shown in Fig. 2, the bottom lamination in Fig. 1 has mounting slots 13 and 14 that correspond to or align with the mounting slots 5 and 6. As shown in Fig. 4, the other lamination that contacts the lamination of the right end in Fig. 1 has mounting slots 7 and 8 that correspond to or align with the mounting slots 5 and 6.

[0040] As shown in Fig. 2, a magnet 4 of the electric motor may be inserted in the magnet mounting slot 3 or the smooth magnet mounting cavity; a gap 11 is formed between an inner wall of the magnet mounting slot 3 and the magnet 4, and the gap 11 runs unobstructed from one end of the rotor main body 1 through to the other end.

[0041] Therefore, a common permanent magnet of a whole regular cuboid shape may be inserted without obstruction from one end of the rotor main body into the smooth magnet mounting cavity, and is arranged in a skewed manner with respect to the extension axis A. By means of the smooth magnet mounting cavity formed at an incline along the extension axis A of the rotor main body 1, not only can a skewed arrangement of a magnet be achieved, but also there is no need for a specially shaped magnet or for split pieces of magnets. In addition, since the gap 11 also runs from one end of the rotor main body 1 through to the other end, a potting process does not need to be performed under pressure, and it is not necessary to provide end plates at both ends of the rotor main body, and the dynamic balance is improved.

[0042] Since the sidewalls of the magnet mounting slots 3 in the respective multiple laminations 2 are slanted at the same second angle 0, as shown in Fig. 5, a first lamination with respect to a last lamination in the multiple laminations 2 deviates by a total angle a, which is equal to an angular spacing D between two stator teeth that are adjacent. The first lamination herein may be the first lamination at one end of the rotor main body 1 , and the last lamination may be the lamination at the other end of the rotor main body. It can be said that Fig. 5 is a projection of the top lamination to the bottom lamination of Fig. 2, or Fig. 5 is a top view of Fig. 2. Further, Fig. 5 is a projection of the upper surface of the top lamination to the upper surface of the bottom lamination. The total angle a is a circumferential included angle between the geometric centre of the magnet mounting slots on the corresponding or aligned top lamination and the geometric centre of the magnet mounting slots on the bottom lamination. In view of Fig. 2, the total angle a may be the circumferential included angle of the geometric centres of the mounting slots 6 and 14. It should be noted that the straight lines in Fig. 5 for partitioning the magnet mounting slots are not physically present and are for illustrative purposes only.

[0043] The first angle described above is equal to the total angle a divided by the number of laminations 2. For example, the first angle may be approximately 0.01 degrees to 0.03 degrees. For example, the first angle may be approximately 0.018 degrees.

[0044] The total angle a of deviation depends on the number of stator slots and the length of the rotor main body. For example, taking the 8-pole 48-slot electric motor shown in Figs. 1 to 6, the total angle a of deviation of the rotor is 7.5 degrees, in order to reduce cogging torque. That is, the total angle a of deviation is the angular spacing D between two stator teeth 18, which can eliminate the 48th harmonic of cogging torque. Therefore, vibration and noise from cogging torque can be significantly reduced. The total angle a described above may also be between 6 and 9 degrees.

[0045] As shown in Figs. 3 and 4, the rotor further comprises interlocking parts, and the interlocking parts are respectively arranged on contact surfaces of the laminations 2 and are distributed in a circumferential direction centred on the extension axis A of the rotor shaft. For example, the interlocking part comprises a protrusion 9 arranged on a contact surface of a lamination of adjacent laminations and a slot 10 on a contact surface of the other lamination, and the protrusion 9 is joined to the slot 10 in an interference fit. Each lamination may have two contact surfaces, wherein one has a protrusion 9 and the other has a slot 10. In fact, the positions of the protrusion 9 and the slot 10 of each lamination are fixed relative to the positions of the magnet mounting slots, and because the first angle of rotation of the laminations is generally small, it is possible for the angle by which the protrusions and slots are staggered when the laminations are mounted to be small. Such a manner of assembly can achieve secure mounting, and is simple in structure and easy to achieve.

[0046] As shown in Fig. 7, an inlet of the magnet mounting slot 3 of each lamination 2 is provided with a rounded edge 12. This rounded edge 12 facilitates the flow of potting into the magnet mounting slot, and therefore further promotes performance of the potting process.

[0047] As described above, the rotor of the electric motor of the present disclosure can realize an inclined smooth magnet mounting cavity, which runs straight from one end of the rotor through to the other end, so that a complex or specially shaped magnet is not needed, the potting process does not need to be performed under pressure, and it is not necessary to provide end plates at both ends of the rotor main body, and the dynamic balance is improved. The rotor of the electric motor and the electric motor are structurally simple and low in cost, and can significantly reduce vibration and noise, and have high reliability. It should be understood that the electric drive system of the present disclosure and the vehicle of the present disclosure also have the advantages described above in relation to the electric motor and the rotor.

[0048] In addition, the technical features disclosed above are not limited to combinations of the disclosed features with other features, and those skilled in the art could combine technical features in other ways according to the objective of the invention, to realize the objective of the present disclosure.

Claims

WHAT IS CLAIMED IS:

1. An electric motor, characterized in that the electric motor comprises: a stator (15), provided with multiple stator teeth (18) and multiple stator slots (16) separated by the multiple stator teeth; and a rotor (17), rotatably arranged inside the stator, wherein the rotor (17) comprises: a rotor shaft, with an extension axis (A); and a rotor main body (1), formed by stacking multiple laminations (2) and capable of rotating around the extension axis (A), wherein a magnet mounting slot (3) is provided in each of the multiple laminations (2); a subsequent lamination in the multiple laminations (2) deviates by a first angle along a first deviation direction (B) with respect to a previous lamination, the first deviation direction (B) being perpendicular to the extension axis (A), and sidewalls of the magnet mounting slots (3) in the respective multiple laminations (2) are slanted at the same second angle (0) to form a smooth magnet mounting cavity of the rotor main body (1).

2. The electric motor according to claim 1, characterized in that a total angle (a) of deviation of a first lamination with respect to a last lamination in the multiple laminations (2) is equal to an angular spacing (D) between two stator teeth (18) that are adjacent.

3. The electric motor according to claim 2, characterized in that the first angle is equal to the total angle (a) divided by the number of laminations (2).

4. The electric motor according to claim 2, characterized in that the total angle (a) is 6 degrees to 9 degrees.

5. The electric motor according to Claim 1, characterized in that the second angle (0) is equal to the angular spacing (D) between two stator teeth (18) that are adjacent.

6. The electric motor according to any one of claims 1 to 5, characterized in that the rotor further comprises interlocking parts, and the interlocking parts arerespectively arranged on contact surfaces of the laminations (2) and are distributed in a circumferential direction centred on the extension axis (A).

7. The electric motor according to claim 6, characterized in that the interlocking part comprises a protrusion (9) arranged on a contact surface of a lamination of adjacent laminations and a slot (10) on a contact surface of the other lamination of the adjacent laminations, and the protrusion (9) is joined to the slot (10) in an interference fit.

8. The electric motor according to any one of claims 1 to 5, characterized in that an inlet of the magnet mounting slot (3) is provided with a rounded edge (12).

9. The electric motor according to any one of claims 1 to 5, characterized in that a gap (11) is formed between an inner wall of the magnet mounting slot (3) and a magnet (4), and the gap runs unobstructed from one end of the rotor main body (1) through to another end.

10. An electric drive system, characterized in that the electric drive system comprises the electric motor according to any one of claims 1 to 9.

11. A vehicle, characterized in that the vehicle comprises the electric motor according to any one of claims 1 to 9, or the electric drive system according to claim 10.

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