An electric drive assembly and electric device

Abstract

This application provides an electric drive assembly and an electric device, relating to the field of electric motors, which enables the amplitude and phase distribution of vibrations excited by gear meshing to be the same in each electric cycle, and has high practicality. The electric drive assembly includes a motor and a reducer. The motor includes a rotor and an output shaft. The rotor is fixedly connected to the output shaft. Multiple magnetic pole pairs are uniformly distributed along the circumferential direction on the rotor. The reducer includes an input shaft, a first gear, and at least one first transmission component. One end of the input shaft is fixedly connected to the output shaft, and the other end is fixedly connected to the first gear, which meshes with the first transmission component. The number of teeth on the first gear is an integer multiple of the number of magnetic pole pairs.

Description

Technical Field

[0001] This application relates to the field of electric motors, and more particularly to an electric drive assembly and an electric device. Background Technology

[0002] In electric actuators (such as electric vehicles), the motor and reducer gears are rigidly connected by a shaft to transmit power. During the rotation of the gears driven by the motor, the meshing force of the reducer gears is transmitted through the internal structure to the external housing, causing forced vibration of the external housing and radiating noise, resulting in high-frequency whistling. This high-frequency whistling problem is particularly pronounced when the meshing frequency of the reducer gears is coupled with the resonant frequency of the structural modes, severely impacting the noise, vibration, and harshness (NVH) performance of the electric actuator. Utility Model Content

[0003] This application provides an electric drive assembly and electric device that enables the amplitude and phase of the vibration excited by the first gear meshing to be the same in each electric cycle (one electric cycle is defined as the angle between adjacent magnetic pole pairs rotated by the motor), facilitating the implementation of noise reduction schemes and demonstrating high practicality. The electric drive assembly and electric vehicle are described in detail below.

[0004] In a first aspect, an electric drive assembly is provided, comprising: a motor and a reducer. The motor includes a rotor and an output shaft. The rotor is fixedly connected to the output shaft. A plurality of magnetic pole pairs are uniformly distributed along a circumferential direction on the rotor. The reducer includes an input shaft, a first gear, and at least one first transmission member. One end of the input shaft is fixedly connected to the output shaft, and the other end of the input shaft is fixedly connected to the first gear, which meshes with the first transmission member. The number of teeth on the first gear is an integer multiple of the number of magnetic pole pairs.

[0005] Based on this scheme, by designing the number of teeth of the first gear in the reducer to be an integer multiple of the number of magnetic pole pairs, it can be ensured that the amplitude and phase of the vibration excited by gear meshing (i.e., the meshing of the first gear and the first transmission component, which will not be elaborated further below) strictly repeat in each electrical cycle. In this way, the electrical angle of the rotor can correspond one-to-one with the amplitude and phase of the vibration excited by gear meshing, which facilitates the implementation of noise reduction schemes (such as determining the phase and amplitude of vibration based on the electrical angle of the rotor, thereby enabling precise control of the parameters of current or voltage harmonic injection, and using motor torque fluctuations to offset the vibration excited by gear meshing, thereby reducing the noise generated by gear meshing).

[0006] In conjunction with the electric drive assembly provided in the first aspect, in some possible implementations, the number of teeth on the first gear is p times the number of magnetic pole pairs, where p is an integer between 5 and 10. Based on this scheme, it is beneficial to optimize the matching between the gear meshing frequency and the electromagnetic excitation of the motor.

[0007] In conjunction with the electric drive assembly provided in the first aspect, in some possible implementations, the number of teeth on the first gear is greater than or equal to 10.

[0008] In conjunction with the electric drive assembly provided in the first aspect, in some possible implementations, the number of magnetic pole pairs is greater than or equal to 2.

[0009] In conjunction with the electric drive assembly provided in the first aspect, in some possible implementations, the number of magnetic pole pairs is 3, and the number of teeth of the first gear is any of the following values: 21, 24, 27, 30.

[0010] In conjunction with the electric drive assembly provided in the first aspect, in some possible implementations, the number of magnetic pole pairs is 4, and the number of teeth of the first gear is any of the following values: 20, 24, 28, 32.

[0011] In conjunction with the electric drive assembly provided in the first aspect, in some possible implementations, the number of magnetic pole pairs is 5, and the number of teeth of the first gear is any of the following values: 20, 25, 30, 35.

[0012] In conjunction with the electric drive assembly provided in the first aspect, in some possible implementations, the number of magnetic pole pairs is 6, and the number of teeth of the first gear is any of the following values: 18, 24, 30, 36.

[0013] In conjunction with the electric drive assembly provided in the first aspect, in some possible implementations, the number of magnetic pole pairs is 8, and the number of teeth of the first gear is any of the following values: 16, 24, 32, 40.

[0014] In conjunction with the electric drive assembly provided in the first aspect, in some possible implementations, the tooth surface of the first gear undergoes a modification process. This modification includes any one or more of the following: tooth tip edge modification and tooth direction drum modification. Based on this approach, tooth tip edge modification can reduce meshing impact, and tooth direction drum modification can optimize load distribution. By performing the aforementioned modification process on the tooth surface of the first gear, the noise generated during gear meshing can be effectively reduced, improving the vehicle's NVH performance and enhancing ride comfort.

[0015] In conjunction with the electric drive assembly provided in the first aspect, in some possible implementations, the surfaces of the motor and reducer are partially or completely covered with an acoustic coating layer, which is used to block and absorb noise. Based on this solution, the airborne transmission paths of motor noise and gear meshing noise can be blocked, which is beneficial to improving the vehicle's NVH performance and enhancing ride comfort.

[0016] In conjunction with the electric drive assembly provided in the first aspect, in some possible implementations, the first gear is a helical gear structure.

[0017] In conjunction with the electric drive assembly provided in the first aspect, in some possible implementations, the relative angle between the magnetic pole pair and the first gear is a pre-set fixed value. Based on this scheme, assembling the relative angle between the magnetic pole pair and the first gear to a fixed value ensures that the number of magnetic pole pairs is the same, and that after assembling electric drive assemblies with the same number of teeth on the first gear, the amplitude and phase of the vibration excited by the meshing of the first gear and the first transmission component in each electric drive assembly are the same in the corresponding electrical period. Thus, uniform parameters can be used for harmonic injection to reduce noise, which helps to reduce the implementation cost of the noise reduction scheme.

[0018] In conjunction with the electric drive assembly provided in the first aspect, in some possible implementations, the output shaft is connected to the input shaft via a first connector. A positioning element is provided on the first connector, and the relative angle between the magnetic pole pair and the first gear is set to a fixed value based on the positioning element.

[0019] In a second aspect, an electric device is provided, comprising: a power input port and an electric drive assembly as described in any of the first aspects. The power input port is connected to the input terminal of a motor in the electric drive assembly, and the power input port is used to receive power to drive the electric drive assembly to operate.

[0020] In conjunction with the electric device provided in the second aspect, in some possible implementations, the electric device is an electric vehicle. The electric vehicle also includes: a frame, wheels, and a power battery. The power battery, electric drive assembly, and wheels are all fixed to the frame. The power battery is electrically connected to the motor in the electric drive assembly via a power input port, and the wheels are drively connected to a reducer in the electric drive assembly. The power battery supplies power to the motor, and the motor drives the wheels to rotate via the reducer.

[0021] Based on this solution, integrating the electric drive assembly provided in the first aspect into electric vehicles can improve the vehicle's NVH performance and enhance ride comfort. Attached Figure Description

[0022] Figure 1 A schematic diagram of the vibration waveform excited by the meshing of a 25-tooth gear, provided for an embodiment of this application;

[0023] Figure 2 A schematic diagram showing the relationship between rotor position, gear vibration waveform, and resolver output electrical angle, provided for an embodiment of this application;

[0024] Figure 3 This is a schematic diagram of the structure of an electric drive assembly provided in an embodiment of this application;

[0025] Figure 4 A schematic diagram showing the relationship between rotor position, gear vibration waveform, and resolver output electrical angle, as provided in an embodiment of this application;

[0026] Figure 5 This is a schematic diagram of another electric drive assembly provided in an embodiment of this application;

[0027] Figure 6 This is a structural schematic diagram of an electric vehicle provided in an embodiment of this application. Detailed Implementation

[0028] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings.

[0029] In the embodiments of this application, the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0030] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation", "connection" and "joining" should be interpreted broadly, for example, they can be fixed connections, detachable connections, mating connections or integral connections; those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0031] In the description of this specification, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0032] To facilitate understanding, the background of this proposal will be introduced below.

[0033] In an electric actuator, the motor drives the primary gear of the reducer (i.e., the gear connected to the motor) to rotate. The meshing of the primary gear generates vibration and radiates noise, affecting the user experience. The following explanation uses an electric vehicle as an example.

[0034] In electric vehicles, NVH (Noise, Vibration, and Harshness) can be used to measure vehicle comfort and reliability. Compared to gasoline vehicles, although the overall sound pressure level of electric vehicles is lower, the high-frequency howling problem is more prominent, affecting ride comfort.

[0035] The electric drive assembly in electric vehicles is one of the main causes of high-frequency whistling. This assembly primarily consists of a motor and a reducer. The motor is the power source of the electric vehicle, converting electrical energy from the battery into mechanical energy to drive the wheels via the output shaft. The motor's output shaft is connected to the reducer's input shaft. The reducer receives the motor's output speed and torque through the input shaft and reduces the motor's output speed and amplifies its output torque through a set of one or more gear pairs (a structure consisting of two or more meshing gears), thereby optimizing power transmission efficiency. However, the meshing of the primary gear with other gears in the reducer can generate noise, resulting in high-frequency whistling.

[0036] For example, such as Figure 1 The diagram shown is a schematic representation of the vibration waveform excited by the meshing of a 25-tooth gear according to an embodiment of this application. Figure 1 As shown, the 25-tooth gear rotates once, meshing 25 times, and the resulting vibration waveform comprises 25 cycles. It should be understood that this waveform diagram indicates the amplitude and phase of the vibration excited by gear meshing during one rotation of the gear.

[0037] A theoretically feasible noise reduction scheme involves, given the amplitude and phase of gear vibration, implementing harmonic injection control to generate additional torque fluctuations in the motor. This counteracts or partially counteracts the vibration, thereby reducing noise radiation. Harmonic injection refers to applying harmonic voltage or injecting harmonic current into the motor windings, altering the air gap flux density distribution and causing additional torque fluctuations. Torque fluctuations refer to the fluctuations in the output torque of the motor's output shaft.

[0038] However, this noise reduction scheme has at least the following problems that need to be solved: how to obtain the amplitude and phase of the noise. These will be discussed in detail below.

[0039] In some possible implementations, a correspondence can be established between the rotor's position and the amplitude and phase distribution of the vibration (hereinafter referred to as the vibration waveform for ease of explanation). In this way, the amplitude and phase of the vibration can be determined from the rotor's position.

[0040] The position of the rotor can be described by mechanical angles. Mechanical angles refer to the physical angles of the rotor's actual rotation. It should be understood that for every one rotation of the rotor, the gear connected to the rotor in the reducer also rotates one revolution. Therefore, there is a basis for establishing a correspondence between the rotor's mechanical angles and the vibration waveforms caused by the gears.

[0041] However, in the motors of electric vehicles, the mechanical angle of the rotor needs to be measured by configuring additional hardware sensors (such as photoelectric encoders, magnetic encoders, etc.), which is costly.

[0042] The rotor position can also be described by electrical angles. An electrical angle is an angular unit that characterizes the spatial distribution of the motor's magnetic field or the alternating state of the current. A complete polarity cycle of the magnetic field (such as N-pole-S-pole-N-pole) or a complete cycle of current exchange is defined as 360° electrical angle.

[0043] The electrical angle is related to the number of pole pairs in the rotor. A motor rotor typically includes multiple pole pairs, each consisting of an N pole (north pole) and an S pole (south pole), evenly distributed along the rotor's circumference. It should be understood that when the rotor has p pole pairs (or the rotor has p pole pairs), the rotor completes one full polarity cycle every 360 / p mechanical angles, i.e., rotates through 360° of electrical angle (i.e., one electrical cycle).

[0044] In the motors of electric vehicles, the rotor's electrical angle can be obtained using resolver signals (used to measure the rotor's electrical angle and speed for motor control), without the need for additional hardware. Therefore, describing the rotor's position using electrical angles is relatively low-cost.

[0045] Please refer to Figure 2 This diagram illustrates the relationship between rotor position, gear vibration waveform, and resolver output electrical angle, as provided in an embodiment of this application. The rotor includes three pole pairs, and the gear connected to the rotor in the reducer has 25 teeth. Figure 2 As shown, one rotation of the rotor consists of three electrical cycles (referred to as electrical cycle 1, electrical cycle 2, and electrical cycle 3, respectively), each corresponding to a segment of the vibration waveform for one rotation of the gear. It should be noted that the resolver electrical angle refers to the electrical angle of the resolver signal (i.e., the angle based on the electrical cycle).

[0046] Depend on Figure 2 It can be seen that the vibration waveform corresponding to each electrical cycle is not the same (i.e., the amplitude and phase distribution of the noise are different within each electrical cycle). For example, the amplitude and phase of the vibration corresponding to the starting point A1 of electrical cycle 1 (i.e., when the mechanical angle is 0°), the amplitude of the vibration corresponding to the starting point B1 of electrical cycle 2 (i.e., when the mechanical angle is 120°), and the amplitude and phase of the vibration corresponding to the starting point C1 of electrical cycle 3 (i.e., when the mechanical angle is 240°) are all different. In other words, the same electrical angle in different electrical cycles corresponds to points with different amplitudes and phases in the vibration waveform. Therefore, under the above hardware design (i.e., the rotor includes 3 magnetic pole pairs, and the gear connected to the rotor in the reducer has 25 teeth), it is impossible to establish a correspondence between electrical angles and vibration waveforms.

[0047] To address the aforementioned issues, this application provides an electric drive assembly and electric device that enables the amplitude and phase distribution of vibrations excited by gear meshing to be identical within each electric cycle, thus possessing high practicality.

[0048] Please refer to Figure 3 This is a schematic diagram of an electric drive assembly provided in an embodiment of this application. Figure 3 As shown, the electric drive assembly 300 includes a motor 301 and a reducer 302. The motor 301 includes a rotor 321 and an output shaft 331. The rotor 321 is fixedly connected to the output shaft 331. The rotor 321 has multiple pairs of magnetic poles 341 evenly distributed along the circumferential direction. The rotor 321 is used to output torque through the output shaft 331. The reducer 302 includes an input shaft 312, a first gear 322, and at least one first transmission element (…). Figure 3 (Not shown in the diagram). One end of the input shaft 312 is fixedly connected to the output shaft 331, and the other end of the input shaft 312 is fixedly connected to the first gear 322. The first gear 322 meshes with the first transmission component. The input shaft 312 is used to rotate under the drive of torque, driving the first gear 322 to rotate. The first gear 322 is used to drive the first transmission component to rotate through the meshing force generated during rotation. The number of teeth of the first gear 322 is an integer multiple of the number of magnetic pole pairs of the motor 301.

[0049] Optionally, the motor 301 may also include a stator 311 arranged around the rotor 321, and the stator 331 is used to drive the rotor 321 to rotate via magnetic pole pairs 341. As an example, Figure 3 When the electric drive assembly shown is in operation, the stator 311 can generate a rotating magnetic field under the action of alternating current. The stator 311 can be composed of an iron core made of laminated silicon steel sheets and multi-phase windings (such as three-phase windings), with each phase winding symmetrically distributed along the circumference and the phase difference between adjacent phase windings being equal. The multi-phase windings and iron core in the stator 311 can generate a rotating magnetic field under the action of alternating current, driving the rotor 321 to rotate through magnetic pole pairs 341.

[0050] The rotor 321 has multiple pole pairs 341 that can rotate under the influence of a rotating magnetic field, driving the output shaft 331 to rotate and output torque. In some possible implementations, the rotor 321 can be composed of an iron core made of stacked silicon steel sheets and permanent magnets (such as a permanent magnet synchronous motor). The permanent magnets can be attached to the surface of the iron core or embedded inside the iron core to form multiple pole pairs. In other possible implementations, the rotor 321 can also be composed of an iron core and DC excitation windings (such as an electrically excited synchronous motor), or an iron core and a squirrel cage (such as an asynchronous motor), or a single iron core (such as a reluctance motor). The embodiments of this application do not limit the specific structure of the rotor.

[0051] The reducer 302 may include at least one pair of gears, where the first gear may be the driving gear in one of the gear pairs, and the first transmission member may be the driven gear in the gear pair that meshes with the first gear. In other examples, the first transmission member may also be a worm gear, rack, or other similar structure, which is not specifically limited in this embodiment.

[0052] The input shaft 312 of the reducer 302 rotates under the drive of the torque, which in turn drives the first gear 322 to rotate. The first gear 322 drives the first transmission component (such as the driven wheel) to rotate, thus driving the vehicle to move normally. The reducer 302 has functions such as increasing torque, reducing speed, and changing the direction of torque transmission. The reducer 302 can amplify the torque output from the motor 301, reduce its speed, and change its transmission direction before outputting it to the wheels, driving the wheels to rotate and enabling the electric vehicle to move normally.

[0053] In this embodiment of the application, by designing the number of teeth of the first gear 322 to be an integer multiple of the number of magnetic pole pairs 341, it can be ensured that the amplitude and phase of the vibration excited by the meshing of the first gear 322 are consistent throughout all electrical cycles.

[0054] For example, please refer to Figure 4 This is a schematic diagram illustrating the relationship between rotor position, gear vibration waveform, and resolver output electrical angle, as provided in another embodiment of this application. The rotor 321 includes three pole pairs, and the first gear 322 has 21 teeth (an integer multiple of 3). Figure 4 As shown, one rotation of the rotor consists of three electrical cycles (referred to as electrical cycle 1, electrical cycle 2 and electrical cycle 3, respectively), and each electrical cycle corresponds to a segment of the waveform shown in the figure for one rotation of the gear.

[0055] Depend on Figure 4 It can be seen that the vibration waveform corresponding to each electrical cycle is the same (i.e., the amplitude and phase of the noise are the same within each electrical cycle). For example, the amplitude and phase of the vibration corresponding to the starting point A2 of electrical cycle 1 (i.e., when the mechanical angle is 0°), the amplitude of the vibration corresponding to the starting point B2 of electrical cycle 2 (i.e., when the mechanical angle is 120°), and the amplitude and phase of the vibration corresponding to the starting point C2 of electrical cycle 3 (i.e., when the mechanical angle is 240°) are all the same. In other words, the same electrical angle in different electrical cycles corresponds to the same amplitude and phase in the vibration waveform. Therefore, it is possible to establish a correspondence between electrical angles and vibration waveforms.

[0056] In other words, the electric drive assembly provided in this application embodiment can achieve a one-to-one correspondence between the electrical angle of the rotor 321 and the amplitude and phase of the vibration excited by the meshing of the first gear 322. This facilitates the determination of the amplitude and phase of the vibration excited by the meshing of the first gear 322 based on the electrical angle of the rotor 321, thereby controlling the parameters of harmonic injection (such as amplitude and phase), and using the torque fluctuation of the motor 301 to offset the vibration excited by the meshing of the first gear 322, thereby reducing the noise generated by the meshing of the first gear 322.

[0057] For example, when using the electric drive assembly 300 provided in the embodiments of this application, the harmonic injection parameters (such as the amplitude, phase, phase sequence, etc. of harmonic current or voltage) that can reduce the average sound pressure level (such as making the average sound pressure level at 1 meter the lowest) can be pre-calibrated in the bench test of the electric drive assembly 300 at different operating points (such as dividing multiple operating points based on the speed or torque of the motor 301) to obtain calibration data.

[0058] When applying calibration data, the system can acquire the electrical angle of rotor 321 in real time (e.g., through resolver signals) and obtain the corresponding harmonic injection parameters from the calibration data in conjunction with the current operating conditions (e.g., motor speed, torque). Since the number of teeth of the first gear 322 is an integer multiple of the number of magnetic pole pairs 341, the phase distribution of the vibration excited by the meshing of the first gear 322 is the same in each electrical cycle. When the motor starts in any electrical cycle, vibration reduction and noise reduction can be achieved through the same set of harmonic injection parameters (the values ​​of the harmonic injection parameters are different under different operating conditions).

[0059] In other examples, when assembling the first gear of the motor and reducer, the assembly can be performed with a pre-set fixed value for the relative angle between the magnetic pole pair and the first gear. The relative angle between the magnetic pole pair and the first gear can refer to the angle between the line connecting a pre-set position (such as N pole, S pole, etc.) on one of the rotor's magnetic pole pairs to the center of the circle (the center of the circle where the magnetic pole pairs are circumferentially distributed), and the line connecting a pre-set position on the first gear (such as the middle of the tip of one tooth, or the midpoint between two adjacent teeth, etc.) to the center of the input shaft. This ensures that after assemblies with the same number of magnetic pole pairs and the same number of teeth on the first gear are assembled, the amplitude and phase of the vibration excited by the meshing of the first gear and the first transmission component in each electric drive assembly are the same in the corresponding electrical cycle (such as the first electrical cycle of the first electric drive assembly and the first electrical cycle of the second electric drive assembly). This facilitates the use of uniform harmonic injection parameters for noise reduction, reducing the implementation cost of the noise reduction scheme.

[0060] Please refer to Figure 5 This is a schematic diagram of another electrically driven structure provided in an embodiment of this application. Figure 5 As shown, the electric drive assembly includes a motor 501 and a reducer. Figure 5The reducer is not shown; only the first gear 506 and input shaft 505 are shown. The motor 501 includes a rotor 507 and an output shaft 503. The rotor 507 is fixedly connected to the output shaft 503. Multiple pairs of magnetic poles 502 are evenly distributed along the circumferential direction on the rotor 507. Figure 5 (Taking a 3-pole pair as an example). The reducer includes an input shaft 505, a first gear 506, and at least one first transmission component (…). Figure 5 (Not shown in the image). One end of the input shaft 505 is fixedly connected to the output shaft 503 via the first connector 504, and the other end of the input shaft 505 is fixedly connected to the first gear 506. The first gear 506 meshes with the first transmission component. Figure 5 (Not shown in the image). The number of teeth on the first gear 506 is an integer multiple of the number of magnetic pole pairs. Figure 5 (Taking a 3x multiplier, i.e., the first gear 506 has 9 teeth as an example).

[0061] Optionally, the motor 501 may also include a stator 508, which is arranged around the rotor 507 and is used to drive the rotor 507 to rotate via magnetic pole pairs 502. For details, please refer to the description in the foregoing embodiments, which will not be repeated here.

[0062] In this embodiment, the first connecting member 504 can be a spline, coupling, etc., and is not limited thereto. A positioning member 514 can be provided on the first connecting member 504, and the relative angle between the magnetic pole pair 502 and the first gear 506 can be set to the aforementioned fixed value based on the positioning member 514. For example, a pre-set position on one of the magnetic pole pairs 502, a pre-set position on the positioning member 514, and a pre-set position on the first gear 506 are located on a straight line.

[0063] The positioning element 514 can be a concave dot, concave line, convex dot, convex line, hole, or other marking, or it can be an existing structure on the positioning element 514. For example, when the first connecting element 504 is a spline, the positioning element 514 can be a tooth in the spline. The specific shape of the positioning element 514 is not limited in the embodiments of this application.

[0064] In some possible implementations, the number of teeth on the first gear can be 5 to 10 times the number of magnetic pole pairs. Specifically, the number of teeth on the first gear can be greater than or equal to 10, and the number of magnetic pole pairs can be greater than or equal to 2.

[0065] In gear design, a higher number of teeth is beneficial for improving the contact ratio of gear meshing, thereby enhancing the gear's NVH performance. However, an excessive number of teeth can lead to a smaller speed ratio (the ratio of the speeds of the driving and driven gears), requiring a higher motor torque output and increasing implementation costs. In practical applications, the number of teeth on the first gear can be designed based on actual needs, and is not limited here. For example, the number of teeth on the first gear can be designed between 16 and 40 to balance the contact ratio and speed ratio requirements, reducing implementation costs.

[0066] In motor design, increasing the number of pole pairs can improve torque output, but it leads to a decrease in speed. This is beneficial for scenarios requiring low speed and high torque (such as the hill-climbing scenario of electric vehicles). Conversely, reducing the number of pole pairs can increase speed, but it leads to a decrease in torque output. This is beneficial for scenarios requiring high speed and low torque (such as the high-speed driving scenario of electric vehicles on flat roads). In practical applications, the number of pole pairs in this application can be designed based on actual needs. For example, a high-speed, low-torque motor can use fewer pole pairs, while a low-speed, high-torque motor can use more pole pairs. This is not limited here. For instance, the number of pole pairs can be designed between 3 and 8 to balance the speed and torque requirements in various scenarios.

[0067] In some examples, the number of magnetic pole pairs can be 3, and the number of teeth on the first gear can be 21, 24, 27, 30, etc. In other examples, the number of magnetic pole pairs can be 4, and the number of teeth on the first gear can be 20, 24, 28, 32, etc. It should be understood that in electric vehicles, the number of magnetic pole pairs is usually 3 or 4. Therefore, the embodiments of this application design the number of magnetic pole pairs to be 3 or 4, which helps to reduce the implementation cost of the solution.

[0068] In other examples, the number of magnetic pole pairs can be 5, and the number of teeth on the first gear can be 20, 25, 30, 35, etc. In other examples, the number of magnetic pole pairs can be 6, and the number of teeth on the first gear can be 18, 24, 30, 36, etc. In still other examples, the number of magnetic pole pairs can be 8, and the number of teeth on the first gear can be 16, 24, 32, 40, etc. It should be understood that this is merely an exemplary illustration of the number of magnetic pole pairs and the number of teeth on the first gear, and does not imply that this application is limited thereto.

[0069] In some possible implementations, the first gear can be designed as a helical gear, such as a helical cylindrical gear, to increase the overlap of gear meshing, reduce meshing impact, and thus reduce the noise of gear meshing excitation.

[0070] The first gear can undergo a modification process. This modification may include tooth tip trimming to reduce meshing impact and tooth direction molding to optimize load distribution. This effectively reduces noise generated during gear meshing.

[0071] In some possible implementations, the surfaces of the motor and reducer housings can be partially or completely covered with an acoustic wrapping layer for noise reduction, thereby blocking the airborne transmission paths of motor noise and gear meshing noise and further reducing noise. Exemplarily, the acoustic wrapping layer may include a sound-absorbing layer adhered to the outer surface of the housing and a sound-insulating layer covering the sound-absorbing layer. The sound-absorbing layer may be a porous fiber material layer, and the sound-insulating layer may be a high-density rubber or metal foil layer. The acoustic wrapping layer can be fixed to the outer surface of the housing by clamps or bolts, and clearance holes matching the shaft diameter can be provided at the protrusion positions of the motor's output shaft and the reducer's input shaft.

[0072] This application also provides an electric device, including a power input port and an electric drive assembly as described in any of the foregoing embodiments. The power input port is connected to the input terminal of the motor in the electric drive assembly, and is used to receive power to drive the electric drive assembly. Exemplarily, the electric device may also include a battery, and the power input port may be connected to the output terminal of the battery to receive power from the battery. In other examples, the power input port may be connected to an external power source to receive power from an external power source, which is not limited here.

[0073] For example, the above-described electric device can be an electric vehicle. Please refer to... Figure 6 This is a structural schematic diagram of an electric vehicle provided in an embodiment of this application. Figure 6 As shown, the electric vehicle 600 includes: a frame 601, wheels 602, a power battery 603, and an electric drive assembly 604 as described in the preceding embodiments. The power battery 603, the electric drive assembly 604, and the wheels 602 are all fixed to the frame 601. The power battery 603 is electrically connected to a motor 614 in the electric drive assembly 604, and the wheels 602 are driveably connected to a reducer 624 in the electric drive assembly 604. The power battery 603 supplies power to the motor 614, and the motor 614 drives the wheels 602 to rotate via the reducer 624.

[0074] It should be understood that Figure 6 The descriptions of the location and size of each component are merely illustrative. The connections between the components can be direct or indirect, through other components. Figure 6 The illustrated structure does not constitute a specific limitation on the electric vehicle 600. In other embodiments provided in this application, the electric vehicle 600 may include more or more components than illustrated, or combine some components, or split some components, or have different component arrangements. This application does not limit any of these aspects.

[0075] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit it. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. An electric drive assembly, characterized by include: Motors and speed reducers; The motor includes a rotor and an output shaft. The rotor is fixedly connected to the output shaft, and the rotor is provided with a plurality of magnetic pole pairs evenly distributed along the circumferential direction. The reducer includes an input shaft, a first gear, and at least one first transmission component; one end of the input shaft is fixedly connected to the output shaft, and the other end of the input shaft is fixedly connected to the first gear, wherein the first gear and the first transmission component mesh. The number of teeth on the first gear is an integer multiple of the number of magnetic pole pairs.

2. The electric drive assembly of claim 1, wherein, The number of teeth of the first gear is p times the number of the magnetic pole pairs, where p is an integer between 5 and 10.

3. An electric drive assembly according to claim 1 or 2, characterized in that The first gear has 10 or more teeth.

4. The electric drive assembly of any of claims 1-3, wherein, The number of magnetic pole pairs is greater than or equal to 2.

5. The electric drive assembly of any of claims 1-4, wherein, The number of magnetic pole pairs is 3, and the number of teeth of the first gear is any one of the following values: 21, 24, 27, 30.

6. The electric drive assembly according to any one of claims 1-4, characterized in that, The number of magnetic pole pairs is 4, and the number of teeth of the first gear is any one of the following values: 20, 24, 28, 32.

7. The electric drive assembly of any one of claims 1-4, wherein, The number of magnetic pole pairs is 5, and the number of teeth of the first gear is any one of the following values: 20, 25, 30, 35.

8. The electric drive assembly according to any one of claims 1-7, characterized in that, The first gear has a helical tooth structure.

9. The electric drive assembly of any of claims 1-8, wherein, The relative angle between the magnetic pole pair and the first gear is a preset fixed value.

10. The electric drive assembly of claim 9, wherein, The output shaft is connected to the input shaft via a first connector; a positioning element is provided on the first connector, and the relative angle between the magnetic pole pair and the first gear is set to a fixed value based on the positioning element.

11. An electrically powered device, characterized in that include: A power input port and an electric drive assembly as described in any one of claims 1-10; the power input port is connected to the input terminal of the motor in the electric drive assembly, and the power input port is used to receive power to drive the electric drive assembly to work.

12. The electrically powered device of claim 11, wherein, The electric device is an electric vehicle; The electric vehicle also includes: a frame, wheels, and a power battery; The power battery, the electric drive assembly, and the wheels are all fixed to the vehicle frame. The power battery is electrically connected to the motor in the electric drive assembly through the power input port, and the wheels are connected to the reducer in the electric drive assembly. The power battery is used to supply power to the motor, and the motor is used to drive the wheel to rotate through the reducer.

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