WO2023103224A1

WO2023103224A1 - Electric motor, electric power steering system, and vehicle

Info

Publication number: WO2023103224A1
Application number: PCT/CN2022/082602
Authority: WO
Inventors: 朱莲莉; 徐珂; 葛笑
Original assignee: 安徽威灵汽车部件有限公司; 广东威灵汽车部件有限公司
Priority date: 2021-12-06
Filing date: 2022-03-23
Publication date: 2023-06-15
Also published as: CN116231894A

Abstract

Provided in the present application are an electric motor, an electric power steering system, and a vehicle. The electric motor comprises a stator iron core, a rotor iron core and an air gap, wherein the rotor iron core is arranged inside the stator iron core, and the air gap is located between the rotor iron core and the stator iron core. The axial height Ls of the stator iron core, the outer diameter Dso of the stator iron core, the stator split-ratio k of the stator iron core, the axial height Lr of the rotor iron core, and the width lg of the air gap satisfy: (I). In the present application, by means of optimizing the size relationship between a stator iron core, a rotor iron core and an air gap between the two, the problem of performance degradation of an electric motor caused by magnetic flux leakage at an end portion of the electric motor can be effectively solved without adding parts, such that the cogging torque is reduced, torque ripple is suppressed, the average torque of the electric motor is increased, and vibration noise of the electric motor is alleviated; and the weight of the electric motor can be reduced to the greatest possible extent while ensuring the performance of the electric motor, and the production cost is reduced.

Description

Electric Motors, Electric Power Steering Systems and Vehicles

This application claims priority to a Chinese patent application with application number 202111475494.5 and titled "Motor, Electric Power Steering System, and Vehicle" filed with the State Intellectual Property Office of China on December 06, 2021, the entire contents of which are incorporated by reference in this application.

technical field

The present application relates to the technical field of motors, in particular, to a motor, an electric power steering system and a vehicle.

Background technique

At present, the motor inevitably has the problem of magnetic flux leakage at the end, which seriously affects the performance of the motor's output torque and torque ripple, and deteriorates the mechanical vibration and noise of the motor.

However, when relevant measures are taken to suppress the impact of the end magnetic flux leakage on the performance of the motor, new problems of increased weight and cost of the motor will arise. Then, how to effectively suppress the magnetic flux leakage at the end and ensure the performance of the motor without increasing the weight and production cost of the motor has become an urgent problem to be solved.

Contents of the invention

This application aims to solve at least one of the technical problems existing in the prior art or related art.

To this end, a first aspect of the present application consists in proposing an electric machine.

The second aspect of the present application is to propose an electric power steering system.

A third aspect of the present application is to provide a vehicle.

In view of this, according to the first aspect of the present application, a motor is provided, which includes a stator core, a rotor core and an air gap, the rotor core is set inside the stator core, and the air gap is located between the rotor core and the stator core. between cores. Among them, the axial height Ls of the stator core, the outer diameter Dso of the stator core, the stator split ratio k of the stator core, the axial height Lr of the rotor core, and the width lg of the air gap satisfy:

The motor provided by the application includes a stator core, a rotor core and an air gap, an air gap is provided between the rotor core and the stator core, and the rotor core can rotate relative to the stator core. Among them, the axial height of the stator core is Ls, the axial height of the rotor core is Lr, the absolute value of the difference between the axial heights of the stator core and the rotor core is |Ls-Lr|, the outer diameter of the stator core The diameter is Dso, the stator crack ratio of the stator core is k, the stator crack ratio is the ratio of the inner diameter of the stator core to the outer diameter of the stator core, and the width of the air gap is lg to satisfy the above relationship. This application can effectively solve the problem of motor performance degradation caused by magnetic flux leakage at the end of the motor by optimizing the dimensional relationship between the stator core, the rotor core and the air gap between them, without increasing the number of components. Therefore, the cogging torque is reduced, torque ripple is suppressed, the average torque of the motor is increased, and the vibration noise of the motor is improved. While ensuring the performance of the motor, the weight of the motor can be reduced to the greatest extent, and the production cost can be reduced.

Further, will

Denote it as X, and denote the absolute value |Ls-Lr| of the difference in axial height between the stator core and the rotor core as ΔL. Based on the fact that the axial height Ls of the stator core is equal to the axial height Lr of the rotor core, that is, the result of Ls=Lr, ΔL=X=0 is used as a comparison benchmark to study the changes in motor performance and cost under different ΔL. Tave* and Cost* are per unit values (also known as per unit values), Tave* is the ratio of the torque value under different X to the average torque under X=0, and Cost* is the motor cost under different X The ratio of the cost of the motor to the case of X=0. When 0≤X≤0.4, Tave* is at an optimal level, and Cost* is maintained at a low level, so that the average torque output can be guaranteed, the performance of the motor will not be affected by the end magnetic flux leakage, and it can also control Motor production costs.

Wherein, it should be noted that the cogging torque refers to the torque generated by the magnetic field generated by the permanent magnet and the cogging action of the armature when the armature winding is open. The cogging torque is the tangential component of the force between the magnetic field of the permanent magnet and the cogging. Cogging torque always tries to position the rotor in a certain position, also known as cogging torque. The cogging torque causes the torque and speed fluctuations of the motor, causing the motor to generate vibration and noise. When the frequency of the torque ripple is consistent with the resonance frequency of the armature current, resonance will occur, which will inevitably amplify the vibration and noise of the cogging torque , Seriously affect the positioning accuracy and servo performance of the motor, especially at low speeds. Among them, when the torque ripple is too large, the stability of the mechanical load energy dragged by the motor will be reduced, and the performance of the motor will be affected at this time.

Among them, for permanent magnet motors, torque ripple mainly includes ripple torque ripple and reluctance torque ripple, and ripple torque refers to the high-order harmonics in the back EMF and the high-order harmonics in the armature current Part of the torque fluctuation caused by the reluctance torque fluctuation refers to the partial torque fluctuation caused by the uneven inductance of the direct axis and the quadrature axis of the motor caused by the uneven reluctance of the rotor.

The per unit value is a kind of relative unit system, and it is also a numerical marking method commonly used in power system analysis and engineering calculations. It represents the relative value of each physical quantity and parameter, and the unit is pu (it can also be considered dimensionless). In power system calculations, per unit values are also widely used.

In a possible design, further, the axial height Ls of the stator core, the outer diameter Dso of the stator core, the stator split ratio k of the stator core, the axial height of the rotor core Lr, the air gap The width lg satisfies:

In this design, when 0≤X<0.02, as X increases, Cost* basically shows a linear increase trend, and Tave* also shows an upward trend. However, the increase ratio of Tave* is less than 1%, that is, when X is located [0,0.02) interval, parameter changes have a limited effect on the optimization of motor performance. As X increases, when it satisfies 0.02≤X≤0.12, Cost* basically shows a linear increase trend, and Tave* also shows a significant upward trend. At this time, the upward trend of motor cost is not obvious, but the motor performance is significantly improved. When X continues to increase and satisfies 0.12<X≤0.4, Cost* shows a linear increase trend, but Tave* remains basically unchanged, that is to say, within this range, the cost of the motor increases but the performance of the motor does not change, that is In this range, parameter changes have little contribution to the cost performance of the motor. Therefore, choosing 0.02≤X≤0.12 can not only control the cost of the motor well, but also effectively improve the performance of the motor and improve the cost performance of the whole motor.

In a possible design, further, the value range of the stator split ratio k satisfies: 0<k≤0.7.

In this design, the stator split ratio is the ratio of the inner diameter to the outer diameter of the specified stator core. By optimizing the stator split ratio, the torque density can be improved, thereby improving the performance of the motor.

In a possible design, further, the width lg of the air gap satisfies:

In this design, the air gap is located between the stator core and the rotor core, and the width of the air gap needs to satisfy the above relationship, so that the width of the air gap is within an appropriate range. The size of the air gap determines the magnitude of the magnetic flux. If the air gap is too large, the reluctance will increase, the magnetic flux will decrease and the flux leakage will increase, so that the efficiency of the motor will decrease. If the air gap is too small, on the one hand, the air gap is too small to affect the manufacturing process, and the assembly between the rotor core and the stator core is difficult; on the other hand, when the rotor core rotates relative to the stator core, friction between the two is likely to occur , causing sweeping and burning out the motor.

It should be noted that the stator core includes a stator yoke and a plurality of stator teeth, the plurality of stator teeth are connected to the stator yoke at intervals, the air gap is located between the stator teeth and the rotor core, and the width of the air gap is lg Refers to the radial distance between the rotor core and the stator teeth.

In a possible design, further, the central axis of the stator core overlaps with the central axis of the rotor core.

In this design, the central axis of the rotor core coincides with the central axis of the stator core. When the rotor core rotates relative to the stator core, the rotation space required by the rotor core is a regular cylinder. It is installed inside the stator core, or outside the stator core. The coincidence of the central axes of the two can reduce the required radial space as much as possible, so that the radial size of the motor can be effectively controlled, and it is suitable for the complete motor. miniaturization development trend.

Specifically, when the central axis of the rotor core does not coincide with the central axis of the stator core, the rotor core is arranged eccentrically relative to the stator core, and the radial dimension occupied by the two will be larger, contrary to the motor miniaturization development trend.

In a possible design, further, the motor further includes magnet slots and first permanent magnets, the magnet slots are opened axially through the rotor core, and the first permanent magnets are arranged in the magnet slots.

In this design, a magnet slot is provided on the rotor core, and the magnet slot runs through the interior of the rotor core. The first permanent magnet is embedded in the magnet slot and contacts the rotor core. The magnet slot is convenient for the first permanent magnet Positioning installation ensures the position stability of the first permanent magnet. When the first permanent magnet inside the rotor core rotates synchronously with the rotor core, the groove wall of the magnet groove can provide multi-directional position limitation for the first permanent magnet. Ensure the positional stability of the rotor core and the first permanent magnet.

Wherein, the number of magnet slots is multiple, and the multiple magnet slots are distributed on the rotor core at intervals along the circumferential direction, the number of first permanent magnets is multiple, and one first permanent magnet is embedded in one magnet slot.

In a possible design, further, the motor further includes a second permanent magnet, and the second permanent magnet is arranged on a side of the rotor core facing the stator core.

In this design, the rotor core includes a side surface in the circumferential direction, and when the rotor core is located inside the stator core, the second permanent magnet is attached to the outer peripheral surface of the rotor core. When the rotor core is located outside the stator core, the second permanent magnet is attached to the inner peripheral surface of the rotor core. It is worth noting that the second permanent magnet is located between the rotor core and the stator core.

Wherein, the second permanent magnet may be glued to the rotor iron core, or the second permanent magnet may be fixed to the rotor iron core by injection molding.

In a possible design, further, there are multiple second permanent magnets, and the multiple second permanent magnets are evenly spaced.

In this design, a plurality of second permanent magnets are evenly spaced and surface-attached on the side of the rotor core, which improves the structural symmetry and thus improves the efficiency of the motor.

In a possible design, further, the rotor core includes core segments arranged in the axial direction, and the number of core segments is at least two.

In this design, the rotor core includes core segments, the number of core segments is at least two, and at least two core segments are stacked in the axial direction. The main purpose of the segmented design of the rotor core is to obtain a skewed pole rotor, that is, a certain angle is staggered in the circumferential direction between two adjacent core segments. The role of the skewed pole rotor is to reduce the cogging speed of the motor. torque and torque ripple, improving motor performance.

In addition, in the processing and preparation process of the rotor core, the core segments can be formed by stacking the rotor punches, and then the core segments are stacked, so that the formation of the rotor core is divided into two steps, which can be well controlled The accuracy of stacking, early detection of stacking deviations, ensures the stacking accuracy of rotor cores. When multiple rotor punches are used to directly stack the rotor core, it is very difficult to stack.

In a possible design, further, the air gap is a uniform air gap.

In this design, the stator core includes a stator yoke and a stator tooth. The stator tooth is connected to the stator yoke. The stator tooth is arranged close to the rotor core relative to the stator yoke. Between the stator tooth and the rotor core Has an air gap. The air gap is made to be a uniform air gap, that is, the distance between each position of the stator teeth and the rotor core is equal. At this time, the output torque of the motor is large, the power density is high, and the efficiency is high.

In a possible design, further, the air gap is a non-uniform air gap.

In this design, the number of stator teeth is multiple, and the distance between different positions of each stator tooth and the rotor core is not exactly equal, that is, along the circumferential direction, it can gradually increase or decrease, or be first increase and then decrease. When the distance between the stator teeth and the rotor core is uneven, the magnetic field waveform can be improved, the cogging torque amplitude can be reduced, and the loss of the rotor core can also be reduced through the reasonable setting of the uneven air gap. The output torque is increased, so that the performance of the motor is improved.

In a possible design, further, the stator core includes a stator yoke and a plurality of stator teeth, the plurality of stator teeth are connected to the stator yoke at intervals, and the plurality of stator teeth surround the rotor cavity, and the rotor The iron core is located in the rotor cavity.

In this design, the stator core includes a stator yoke and a plurality of stator teeth. The stator yoke is in a ring structure, and the plurality of stator teeth are connected to the stator yoke at intervals. The rotor cavity is formed by a plurality of stator teeth. The rotor cavity is located inside the stator core, and the rotor core is located in the rotor cavity, that is to say, the rotor core is an inner rotor. The air gap is located between the stator teeth and the rotor core, and the width of the air gap is the radial distance between the specified stator teeth and the rotor core.

In a possible design, further, the stator core includes a plurality of iron core blocks, and the plurality of iron core blocks are spliced along the circumferential direction.

In this design, the stator core includes a plurality of iron core blocks, and each iron core block includes a sub-yoke and a stator tooth. The plurality of iron core blocks are spliced along the circumferential direction, and the multiple sub-yokes are spliced and connected to each other to form a stator. The yoke has a ring structure. That is to say, the stator yoke can be an integral ring structure, or can be formed by splicing multiple sub-yokes. The segmented stator core can facilitate the winding of the stator winding. After each core block completes the winding of the stator winding, it is spliced and assembled to form a complete stator core, which is convenient for the winding of the stator winding and can also improve the phase The slot fullness ratio of the stator slot between two adjacent stator teeth enables the stator winding to be better arranged in the stator slot, and the stator winding assembly is improved to improve the performance of the motor.

According to a second aspect of the present application, an electric power steering system is provided, including the motor provided by any of the above-mentioned designs.

The electric power steering system provided by the present application includes the motor provided by any of the above-mentioned designs, so it has all the beneficial effects of the motor, and will not be repeated here.

Among them, the electric power steering system (Electric Power Steering, abbreviated EPS) is a power steering system that directly relies on the motor to provide auxiliary torque. Compared with the traditional hydraulic power steering system HPS (Hydraulic Power Steering), the structure of the EPS system is simple. The assembly is flexible, which can save energy and protect the environment. Most models of modern vehicles are basically equipped with EPS systems. EPS is mainly composed of torque sensor, vehicle speed sensor, motor, reduction mechanism and electronic control unit (ECU).

According to a third aspect of the present application, a vehicle is provided, including the motor or the electric power steering system provided by any of the above-mentioned designs.

The vehicle provided by the present application includes the motor or the electric power steering system provided by any of the above-mentioned designs, so it has all the beneficial effects of the motor or the electric power steering system, and will not be repeated here.

It should be noted that vehicles include new energy vehicles and traditional fuel vehicles.

Additional aspects and advantages of the application will become apparent in the description which follows, or may be learned by practice of the application.

Description of drawings

The above and/or additional aspects and advantages of the present application will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, wherein:

Fig. 1 shows a schematic structural diagram of a motor according to an embodiment of the present application;

Fig. 2 shows a graph according to an embodiment of the present application in motor performance and cost analysis;

Fig. 3 shows a schematic structural diagram of a motor with a uniform air gap according to an embodiment of the present application;

Fig. 4 shows a schematic structural diagram of a motor with a non-uniform air gap according to an embodiment of the present application;

Fig. 5 shows a schematic structural diagram of a motor having a second permanent magnet according to an embodiment of the present application;

Fig. 6 shows a schematic structural diagram of an iron core block according to an embodiment of the present application;

Fig. 7 shows a schematic structural diagram of an electric power steering system according to an embodiment of the present application.

Wherein, the corresponding relationship between the reference numerals and the part names in Fig. 1 to Fig. 7 is:

100 motors,

110 stator core, 111 stator yoke, 112 stator teeth, 113 core block,

120 rotor core, 121 core section,

130 air gap,

140 magnet slots, 141 first permanent magnets, 142 second permanent magnets,

200 electric power steering system,

211 steering wheel, 212 steering shaft, 213 universal coupling, 214 rotating shaft, 215 rack and pinion mechanism, 216 rack shaft, 217 wheels,

221 steering torque sensor, 222 control unit, 223 speed reduction mechanism.

Detailed ways

In order to better understand the above-mentioned purpose, features and advantages of the present application, the present application will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be noted that, in the case of no conflict, the embodiments of the present application and the features in the embodiments can be combined with each other.

In the following description, many specific details are set forth in order to fully understand the application, but the application can also be implemented in other ways different from those described here, therefore, the protection scope of the application is not limited by the specific details disclosed below. EXAMPLE LIMITATIONS.

A motor 100 , an electric power steering system and a vehicle provided according to some embodiments of the present application are described below with reference to FIGS. 1 to 7 .

According to an embodiment of the first aspect of the present application, as shown in FIG. 1 , a motor 100 is provided, which includes a stator core 110, a rotor core 120 and an air gap 130. Internally, an air gap 130 is located between the rotor core 120 and the stator core 110 . Wherein, the axial height Ls of the stator core 110, the outer diameter Dso of the stator core 110, the stator split ratio k of the stator core 110, the axial height Lr of the rotor core 120, and the width lg of the air gap 130 satisfy:

The motor 100 provided in the present application includes a stator core 110 , a rotor core 120 and an air gap 130 . There is an air gap 130 between the rotor core 120 and the stator core 110 . The rotor core 120 can rotate relative to the stator core 110 . Wherein, the axial height of the stator core 110 is Ls, the axial height of the rotor core 120 is Lr, the absolute value of the difference between the axial heights of the stator core 110 and the rotor core 120 is |Ls-Lr|, the stator The outer diameter of the iron core 110 is Dso, the stator split ratio of the stator iron core 110 is k, the stator split ratio is the ratio of the inner diameter of the stator iron core 110 to the outer diameter of the stator iron core 110, and the width of the air gap 130 is lg to satisfy the above relationship. In this application, by optimizing the dimensional relationship between the stator core 110, the rotor core 120 and the air gap 130 between them, the problem of the motor 100 caused by the magnetic flux leakage at the end of the motor 100 can be effectively solved without adding parts. The problem of performance degradation, thereby reducing cogging torque, suppressing torque ripple, increasing the average torque of the motor 100, improving the vibration and noise of the motor 100, while ensuring the performance of the motor 100, can minimize the weight of the motor 100, and reduce production costs.

Wherein, it should be noted that, as shown in FIG. 2 , the magnetic flux leakage at the end of the motor in the related art exists on both axial end faces of the motor, which is unavoidable. There are permanent magnets in the rotor core, and most of the total magnetic flux provided by the permanent magnets close to the axial end face will form the main magnetic flux along the main magnetic circuit and the winding chain on the stator core, and there is a part due to the end effect The magnetic flux that is not linked with the winding turns, this part of the end flux leakage will not only cause the motor torque to drop, but also affect the cogging torque and torque ripple of the motor, and deteriorate the vibration and noise of the motor.

Further, will

Denote X, and denote the absolute value |Ls−Lr| of the difference in axial height between the stator core 110 and the rotor core 120 as ΔL. Based on the fact that the axial height Ls of the stator core 110 is equal to the axial height Lr of the rotor core 120, that is, the result of Ls=Lr, ΔL=X=0, the performance and cost of the motor 100 under different ΔL are studied. The change. As shown in Figure 2, Tave* and Cost* in the figure are per unit values (also known as per unit values), Tave* is the ratio of the torque value under different X to the average torque under X=0, and Cost * is the ratio of the cost of the motor 100 under different X to the cost of the motor 100 when X=0. When 0≤X≤0.4, Tave* is at an optimal level, and Cost* is maintained at a low level, so that the average torque output can be guaranteed, and the performance of the motor 100 will not be affected by the magnetic flux leakage at the end. Control the production cost of the motor 100 .

Wherein, it should be noted that the cogging torque refers to the torque generated by the magnetic field generated by the permanent magnet and the cogging action of the armature when the armature winding is open. The cogging torque is the tangential component of the force between the magnetic field of the permanent magnet and the cogging. Cogging torque always tries to position the rotor in a certain position, also known as cogging torque. The cogging torque causes the torque and speed fluctuations of the motor 100, causing the motor 100 to generate vibration and noise. When the frequency of the torque ripple is consistent with the resonance frequency of the armature current, resonance will occur, which will inevitably amplify the vibration of the cogging torque and noise seriously affect the positioning accuracy and servo performance of the motor 100, especially at low speeds. Wherein, when the torque ripple is too large, the stability of the mechanical load energy dragged by the motor 100 will be reduced, and the performance of the motor 100 will be affected at this time.

Further, as shown in Figures 1 and 2, the axial height Ls of the stator core 110, the outer diameter Dso of the stator core 110, the stator split ratio k of the stator core 110, and the axial height of the rotor core 120 are The width lg of Lr and the air gap 130 satisfies:

In this embodiment, as shown in Figure 2, when 0≤X<0.02, as X increases, Cost* basically shows a linear increase trend, and Tave* also shows an upward trend, but the increase ratio of Tave* is lower than 1%, that is, when X is in the interval [0, 0.02), the effect of parameter changes on optimizing the performance of the motor 100 is limited. As X increases, when it satisfies 0.02≤X≤0.12, Cost* basically shows a linear increase trend, and Tave* also shows a significant upward trend. At this time, the cost increase trend of the motor 100 is not obvious, but the performance of the motor 100 is significantly improved. When X continues to increase and satisfies 0.12<X≤0.4, Cost* shows a linear increase trend, but Tave* basically remains unchanged, that is to say, within this range, the cost of the motor 100 increases but the performance of the motor 100 does not change , that is, within this range, parameter changes have little contribution to the cost performance of the motor 100 . Therefore, choosing 0.02≤X≤0.12 can not only control the cost of the motor 100 well, but also effectively improve the performance of the motor 100 and improve the cost performance of the whole motor 100 .

Further, the value range of the stator split ratio k satisfies: 0<k≤0.7.

In this embodiment, the stator split ratio refers to the ratio of the inner diameter to the outer diameter of the stator core 110 . By optimizing the stator split ratio, the torque density can be improved, thereby improving the performance of the motor 100 .

Further, the width lg of the air gap 130 satisfies:

In this embodiment, the air gap 130 is located between the stator core 110 and the rotor core 120, and the width of the air gap 130 needs to satisfy the above relational expression, so that the width of the air gap 130 is within an appropriate range, and the width of the air gap 130 The size determines the size of the magnetic flux. If the air gap 130 is too large, the reluctance increases, the magnetic flux decreases and the flux leakage increases, so that the efficiency of the motor 100 decreases. If the air gap 130 is too small, on the one hand, the air gap 130 is too small to affect the manufacturing process, and the assembly between the rotor core 120 and the stator core 110 is difficult; on the other hand, when the rotor core 120 rotates relative to the stator core 110, the two Friction easily occurs between the two, causing sweeping and burning out the motor 100.

It should be noted that the stator core 110 includes a stator yoke 111 and a plurality of stator teeth 112, the plurality of stator teeth 112 are connected to the stator yoke 111 at intervals, and the air gap 130 is located between the stator teeth 112 and the rotor core 120 Between, the width lg of the air gap 130 refers to the radial distance between the rotor core 120 and the stator teeth 112 .

Further, as shown in FIG. 1 , the central axis of the stator core 110 overlaps with the central axis of the rotor core 120 .

In this embodiment, the central axis of the rotor core 120 coincides with the central axis of the stator core 110, so when the rotor core 120 rotates relative to the stator core 110, the rotation space required by the rotor core 120 is a regular cylinder body, a regular cylinder is sheathed inside the stator core 110, or sheathed outside the stator core 110, and the central axes of the two coincide to reduce the required radial space as much as possible, so that the radial dimension of the motor 100 It is effectively controlled and adapted to the miniaturization development trend of the motor 100 as a whole.

Specifically, when the central axis of the rotor core 120 does not coincide with the central axis of the stator core 110, the rotor core 120 is arranged eccentrically relative to the stator core 110, and the radial dimension occupied by the two will be larger. It goes against the miniaturization development trend of the motor 100 .

Further, as shown in FIG. 1 , FIG. 3 and FIG. 4 , the motor 100 also includes a magnet slot 140 and a first permanent magnet 141 , the magnet slot 140 penetrates through the rotor core 120 in the axial direction, and the first permanent magnet 141 is set in the magnet slot 140 .

In this embodiment, the rotor core 120 is provided with a magnet slot 140, the magnet slot 140 is opened inside the rotor core 120, the first permanent magnet 141 is embedded in the magnet slot 140 and contacts with the rotor core 120, The magnet slot 140 facilitates the positioning and installation of the first permanent magnet 141, ensuring the positional stability of the first permanent magnet 141. The slot wall can provide multi-directional position limitation for the first permanent magnet 141 to ensure the positional stability of the rotor core 120 and the first permanent magnet 141 .

Wherein, the number of magnet slots 140 is multiple, and the plurality of magnet slots 140 are distributed on the rotor core 120 at intervals along the circumferential direction, and the number of first permanent magnets 141 is multiple, and one first permanent magnet 141 is embedded in one magnet slot 140 Inside.

Further, as shown in FIG. 5 , the motor 100 further includes a second permanent magnet 142 disposed on a side of the rotor core 120 facing the stator core 110 .

In this embodiment, the rotor core 120 includes a side surface in the circumferential direction. When the rotor core 120 is located inside the stator core 110 , the second permanent magnet 142 is attached to the outer peripheral surface of the rotor core 120 . When the rotor core 120 is located outside the stator core 110, the second permanent magnet 142 is pasted on the inner peripheral surface of the rotor core 120. It is worth noting that the second permanent magnet 142 is located between the rotor core 120 and Between the stator cores 110.

Wherein, the second permanent magnet 142 can be glued to the rotor core 120 , or the second permanent magnet 142 can be fixed to the rotor core 120 by injection molding.

Further, as shown in FIG. 5 , there are multiple second permanent magnets 142 , and the multiple second permanent magnets 142 are evenly spaced.

In this embodiment, a plurality of second permanent magnets 142 are evenly spaced and surface-attached on the side of the rotor core 120 to improve structural symmetry and further improve the efficiency of the motor 100 .

Further, as shown in FIG. 1 , the rotor core 120 includes core segments 121 arranged in the axial direction, and the number of core segments 121 is at least two.

In this embodiment, the rotor core 120 includes at least two core segments 121 , and at least two core segments 121 are stacked in the axial direction. The main purpose of the segmented design of the rotor core 120 is to obtain a skewed rotor, that is, a certain angle is staggered between two adjacent iron core segments 121 in the circumferential direction. Cogging torque and torque ripple improve the performance of the motor 100 .

In addition, in the processing and preparation process of the rotor core 120, the core segments 121 can be formed by stacking the rotor punches, and then the core segments 121 are stacked, so that the formation of the rotor core 120 is divided into two steps, which can The accuracy of the stacking is well controlled, the stacking deviation is found early, and the stacking accuracy of the rotor core 120 is ensured. When the rotor core 120 is directly stacked with multiple rotor punches, the stacking is very difficult.

Further, as shown in FIG. 3 and FIG. 5 , the air gap 130 is a uniform air gap.

In this embodiment, the stator core 110 includes a stator yoke 111 and a stator tooth 112, the stator tooth 112 is connected to the stator yoke 111, and the stator tooth 112 is arranged close to the rotor core 120 relative to the stator yoke 111, There is an air gap 130 between the stator teeth 112 and the rotor core 120 . Let the air gap 130 be a uniform air gap, that is, the distance between each position of the stator teeth 112 and the rotor core 120 is equal. At this time, the motor 100 has a large output torque, high power density and high efficiency.

Further, as shown in FIG. 4 , the air gap 130 is a non-uniform air gap.

In this embodiment, the number of stator teeth 112 is multiple, and the distance between different positions of each stator tooth 112 and the rotor core 120 is not completely equal, that is, along the circumferential direction, it can gradually increase or decrease. small, or increase first and then decrease, etc. When the distance between the stator teeth 112 and the rotor core 120 is uneven, the magnetic field waveform can be improved and the amplitude of the cogging torque can be reduced through reasonable setting of the uneven air gap, and at the same time the loss of the rotor core 120 can also be obtained. The output torque of the motor 100 is increased, so that the performance of the motor 100 is improved.

Further, as shown in Figure 1, Figure 3, Figure 4, Figure 5 and Figure 6, the stator core 110 includes a stator yoke 111 and a plurality of stator teeth 112, and the plurality of stator teeth 112 are connected to the stator yoke at intervals 111 , a plurality of stator teeth 112 surround a rotor cavity, and a rotor core 120 is located in the rotor cavity.

In this embodiment, the stator core 110 includes a stator yoke 111 and a plurality of stator teeth 112, the stator yoke 111 is in a ring structure, the plurality of stator teeth 112 are connected to the stator yoke 111 at intervals, and the plurality of stator teeth The portion 112 encloses and forms a rotor cavity, the rotor cavity is located inside the stator core 110, and the rotor core 120 is located in the rotor cavity, that is to say, the rotor core 120 is an inner rotor.

Further, as shown in FIG. 6 , the stator core 110 includes a plurality of iron core blocks 113 , and the plurality of iron core blocks 113 are spliced along the circumferential direction.

In this embodiment, the stator core 110 includes a plurality of iron core blocks 113, and each iron core block 113 includes a sub-yoke and a stator tooth portion 112. The plurality of iron core blocks 113 are spliced along the circumferential direction, and the plurality of sub-yokes The stator yokes 111 are spliced and connected with each other to form a ring structure. That is to say, the stator yoke 111 may be an integral ring structure, or may be formed by splicing a plurality of sub-yokes. The segmented stator core 110 can facilitate the winding of the stator winding. After each core block 113 completes the winding of the stator winding, it is spliced and assembled to form a complete stator core 110, which is convenient for the winding of the stator winding. The slot fullness ratio of the stator slot between two adjacent stator teeth can be improved, the stator winding can be better arranged in the stator slot, and the performance of the motor 100 can be improved by improving the assembly of the stator winding.

According to an embodiment of the second aspect of the present application, an electric power steering system 200 is provided, including the motor 100 provided by any of the above designs.

The electric power steering system 200 provided in the present application, as shown in FIG. 7 , includes the motor 100 provided by any of the above-mentioned designs, so it has all the beneficial effects of the motor 100 and will not be repeated here.

Among them, the electric power steering system 200 (Electric Power Steering, abbreviated EPS) is a power steering system that directly relies on the motor 100 to provide auxiliary torque. Compared with the traditional hydraulic power steering system HPS (Hydraulic Power Steering), the structure of the EPS system Simple, flexible assembly, not only can save energy, but also protect the environment, most models of modern vehicles are basically equipped with EPS system.

Specifically, the EPS system of the present embodiment has a steering system and an assist torque mechanism that generates assist torque. The EPS system generates assist torque that assists the steering torque of the steering system generated by the driver's operation of the steering wheel. The assist torque reduces the driver's operational burden.

Wherein, the steering system specifically includes a steering wheel 211 , a steering shaft 212 , a universal joint 213 , a rotating shaft 214 , a rack and pinion mechanism 215 , a rack shaft 216 , and wheels 217 for left and right steering.

Wherein, the auxiliary torque mechanism specifically includes a steering torque sensor 221 , an electronic control unit (ECU) 222 for a vehicle, an electric motor 100 , a reduction mechanism 223 and the like. Specifically, the steering torque sensor 221 detects the steering torque of the steering system. The control unit 222 generates a drive signal based on the detection signal of the steering torque sensor 221 . The electric motor 100 generates assist torque corresponding to the steering torque according to the drive signal. The electric motor 100 transmits the generated assist torque to the steering system via the reduction mechanism 223 .

Wherein, the motor 100 provided by the present application includes a stator core 110, a rotor core 120 and an air gap 130, an air gap 130 is provided between the rotor core 120 and the stator core 110, and the rotor core 120 can rotate relative to the stator core 110 . Wherein, the axial height of the stator core 110 is Ls, the axial height of the rotor core 120 is Lr, the absolute value of the difference between the axial heights of the stator core 110 and the rotor core 120 is |Ls-Lr|, the stator The outer diameter of the iron core 110 is Dso, the stator split ratio of the stator iron core 110 is k, the stator split ratio is the ratio of the inner diameter of the stator iron core 110 to the outer diameter of the stator iron core 110, and the width of the air gap 130 is lg to satisfy the above relationship. In this application, by optimizing the dimensional relationship between the stator core 110, the rotor core 120 and the air gap 130 between them, the problem of the motor 100 caused by the magnetic flux leakage at the end of the motor 100 can be effectively solved without adding parts. The problem of performance degradation, thereby reducing cogging torque, suppressing torque ripple, increasing the average torque of the motor 100, improving the vibration and noise of the motor 100, while ensuring the performance of the motor 100, can minimize the weight of the motor 100, and reduce production costs.

Wherein, it should be noted that, as shown in FIG. 2 , the magnetic flux leakage at the end of the motor 100 in the related art exists on both axial end surfaces of the motor 100 , which is unavoidable. There are permanent magnets in the rotor core 120, and most of the total magnetic flux provided by the permanent magnets near the axial end faces will form the main magnetic flux along the main magnetic circuit with the winding turns on the stator core 110. The end effect is not linked to the magnetic flux of the winding turns. This part of the end flux leakage will not only cause the torque drop of the motor 100, but also affect the cogging torque and torque ripple of the motor 100, and deteriorate the vibration and noise of the motor 100.

Further, will

Denote X, and denote the absolute value |Ls−Lr| of the difference in axial height between the stator core 110 and the rotor core 120 as ΔL. Based on the fact that the axial height Ls of the stator core 110 is equal to the axial height Lr of the rotor core 120, that is, the result of Ls=Lr, ΔL=X=0, the performance and cost of the motor 100 under different ΔL are studied. The change. As shown in Figure 2, Tave* and Cost* in the figure are per unit values, Tave* is the ratio of the torque value under different X to the average torque when X=0, and Cost* is the 100 cost of the motor under different X The ratio to the cost of the motor 100 in the case of X=0. When 0≤X≤0.4, Tave* is at an optimal level, and Cost* is maintained at a low level, so that the average torque output can be guaranteed, and the performance of the motor 100 will not be affected by the magnetic flux leakage at the end. Control the production cost of the motor 100 .

According to an embodiment of the third aspect of the present application, a vehicle is provided, including the motor 100 or the electric power steering system 200 provided by any of the above designs.

The vehicle provided in the present application includes the motor 100 or the electric power steering system provided by any of the above-mentioned designs, so it has all the beneficial effects of the motor 100 or the electric power steering system 200 , which will not be repeated here.

It should be noted that the vehicle can be a traditional fuel vehicle or a new energy vehicle. Among them, new energy vehicles include pure electric vehicles, extended-range electric vehicles, hybrid vehicles, fuel cell electric vehicles, hydrogen engine vehicles, etc.

Wherein, the motor 100 provided by the present application includes a stator core 110, a rotor core 120 and an air gap 130, an air gap 130 is provided between the rotor core 120 and the stator core 110, and the rotor core 120 can rotate relative to the stator core 110 . Wherein, the axial height of the stator core 110 is Ls, the axial height of the rotor core 120 is Lr, the absolute value of the difference between the axial heights of the stator core 110 and the rotor core 120 is |Ls-Lr|, the stator The outer diameter of the iron core 110 is Dso, the stator split ratio of the stator iron core 110 is k, the stator split ratio is the ratio of the inner diameter of the stator iron core 110 to the outer diameter of the stator iron core 110, and the width of the air gap 130 is lg to satisfy the above relationship. In this application, by optimizing the dimensional relationship between the stator core 110, the rotor core 120 and the air gap 130 between them, the problem of the motor 100 caused by the magnetic flux leakage at the end of the motor 100 can be effectively solved without adding parts. performance degradation, thereby reducing the cogging torque, suppressing torque ripple, increasing the average torque of the motor 100, improving the vibration and noise of the motor 100, and reducing the weight of the motor 100 to the greatest extent while ensuring the performance of the motor 100, and reduce production costs.

Further, will

In this application, the term "plurality" means two or more, unless otherwise clearly defined. The terms "installation", "connection", "connection", "fixed" and other terms should be interpreted in a broad sense, for example, "connection" can be fixed connection, detachable connection, or integral connection; "connection" can be directly or indirectly through an intermediary. Those of ordinary skill in the art can understand the specific meanings of the above terms in this application according to specific situations.

In the description of this specification, descriptions of the terms "one embodiment", "some embodiments", "specific embodiments" and the like mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in this application In at least one embodiment or example of . In this specification, schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

The above descriptions are only preferred embodiments of the present application, and are not intended to limit the present application. For those skilled in the art, there may be various modifications and changes in the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of this application shall be included within the protection scope of this application.

Claims

A motor, including:

stator core;

a rotor core, the rotor core is arranged inside the stator core;

an air gap between said rotor core and said stator core,

Among them, the axial height Ls of the stator core, the outer diameter Dso of the stator core, the stator split ratio k of the stator core, the axial height Lr of the rotor core, and the air gap The width lg satisfies:
The electric machine according to claim 1, wherein,

The axial height Ls of the stator core, the outer diameter Dso of the stator core, the stator split ratio k of the stator core, the axial height Lr of the rotor core, and the width lg of the air gap satisfy:
The electric machine according to claim 2, wherein,

The value range of the stator split ratio k satisfies: 0<k≤0.7.
The electric machine according to claim 1, wherein,

The width lg of the air gap satisfies:
An electric machine according to any one of claims 1 to 4, wherein,

The central axis of the stator core overlaps with the central axis of the rotor core.
The motor according to any one of claims 1 to 4, wherein the motor further comprises:

The magnet slot is axially opened on the rotor core;

The first permanent magnet is arranged in the magnet slot.
The motor according to any one of claims 1 to 4, wherein the motor further comprises:

The second permanent magnet is arranged on the side of the rotor core facing the stator core.
The electric machine according to claim 7, wherein,

There are multiple second permanent magnets, and the multiple second permanent magnets are evenly spaced.
An electric machine according to any one of claims 1 to 4, wherein,

The rotor core includes core segments arranged in the axial direction, and the number of the core segments is at least two.
An electric machine according to any one of claims 1 to 4, wherein,

The air gap is a uniform air gap.
An electric machine according to any one of claims 1 to 4, wherein,

The air gap is a non-uniform air gap.
An electric machine according to any one of claims 1 to 4, wherein,

The stator core includes a stator yoke and a plurality of stator teeth, the plurality of stator teeth are connected to the stator yoke at intervals, the plurality of stator teeth enclose a rotor cavity, and the rotor iron A core is located within the rotor cavity and the air gap is located between the stator teeth and the rotor core.
An electric machine according to any one of claims 1 to 4, wherein,

The stator core includes a plurality of iron core blocks, and the plurality of iron core blocks are spliced along the circumferential direction.
An electric power steering system, comprising the motor according to any one of claims 1 to 13.
A vehicle, comprising: the motor according to any one of claims 1 to 13, or the electric power steering system according to claim 14.