1. An electric drive axle structure with double motors is characterized by comprising a first motor, a second motor, an epicyclic gear train, a driving gear (9), a driven gear (10), a differential, a driving half shaft and a brake (17);

the first motor comprises a first motor stator (1) and a first motor rotor (2), the second motor comprises a second motor stator (3) and a second motor rotor (4), and the first motor stator (1), the first motor rotor (2), the second motor stator (3) and the second motor rotor (4) are all arranged on the shaft (15); the epicyclic gear train comprises a gear ring (5), a planet carrier (7), a sun wheel (8) and a planet wheel (6); the first motor rotor (2) is fixedly connected with the sun gear (8), the second motor rotor (4) is fixedly connected with the gear ring (5), and the gear ring (5) is connected with the brake (17); one side of the planet carrier (7) is connected with the planet wheel (6), the other side of the planet carrier is connected with the driving gear (9), the driving gear (9) is meshed with the driven gear (10), the driven gear (10) is connected with the differential mechanism, and the differential mechanism is connected with the driving half shaft.

2. The electric drive axle structure with two motors according to claim 1, characterized in that the differential includes a differential case (11), differential planetary gears (12), and side gears (13); the drive half shaft comprises a first output half shaft (14) and a second output half shaft (16); the driven gear (10) is connected with a differential case (11), the differential case (11) is connected with a differential planetary gear (12), the differential planetary gear (12) is meshed with a side gear (13), the side gear (13) is respectively connected with a first output half shaft (14) and a second output half shaft (16), and the first output half shaft (14) and the second output half shaft (16) are connected to a hub.

3. The electric transaxle structure having two motors of claim 1 wherein the differential is an anti-slip differential.

4. The electric drive axle structure having dual motors of claim 1, wherein the first motor and the second motor are both hollow shaft motors.

5. The electric drive bridge structure with dual motors of claim 1, wherein the first motor stator (1) and the second motor stator (3) are symmetrically arranged on the shaft (15), and the first motor stator (1) and the second motor stator (3) are mounted on a stator fixing disc through a coupling block, and the stator fixing disc is connected with the shaft (15).

6. The electric drive axle structure with two motors of claim 5, wherein the stator fixing disc is made of non-magnetic material.

7. Electric drive axle construction with double motor according to claim 1, characterized in that the first motor rotor (2) is connected with the sun wheel (8) by means of bolts, the second motor rotor (4) is connected with the ring gear (5) by means of studs, which are connected with the brake (17).

8. The electric drive bridge structure with dual motors of claim 1, wherein the first and second motors are axial flux permanent magnet synchronous motors.

9. The method for operating an electric drive axle structure having two motors as set forth in any one of claims 1 to 8, comprising:

when the automobile runs at a low speed, the gear ring (5) is braked by the brake (17), the epicyclic train is a planetary train with the degree of freedom of 1 at the moment, the power of the first motor is input by the sun gear (8), is output to the driving gear (9) by the planet carrier after being decelerated by the planetary train, the driving gear (9) drives the driven gear (10), the driven gear (10) transmits the power to the differential mechanism, and the differential mechanism transmits the power to the automobile hub by driving the half shaft;

when the automobile runs at a high speed, the brake (17) releases the brake on the gear ring (5), the epicyclic wheel is a differential gear train with the degree of freedom of 2, the power of the first motor is input by the sun gear (8), the power of the second motor is input by the gear ring (5), and is coupled by the differential gear train and then output to the driving gear (9) by the planet carrier, and finally the power is transmitted to the automobile hub.

10. The operating method of an electric drive axle structure having two motors as set forth in claim 9, wherein when the vehicle is running at a low speed, the system reduction ratio is:

the output torque is:

T_H＝i·T_a

the output rotating speed is as follows:

n_H＝n_a/i

wherein n is_aThe rotating speed of the sun wheel (8); n is_HThe rotating speed of the planet carrier (7); z_aThe number of teeth of the sun gear (8); z_bThe number of teeth of the gear ring (5); t is_aIs the output torque of the first motor;

when the automobile runs at high speed, mu is taken_o＝Z_b/Z_a

The output torque is:

T_H＝-(1+μ_o)·T_a＝-(1+μ_o)·T_b/μ_o

the output rotating speed is as follows:

wherein n is_aThe rotating speed of the sun wheel (8); n is_bThe rotating speed of the gear ring (5); n is_HThe rotating speed of the planet carrier (7); t is_bIs the output torque of the second motor; z_aThe number of teeth of the sun gear (8); z_bThe number of teeth of the gear ring (5); mu.s_oIs a characteristic parameter of the epicyclic gear train.

Background

The rapid development of the electric automobile industry has become a necessary trend, and will eventually promote the electric motorization of the automobile industry, and extended-range automobiles play an important role in the industry. The axle product is used as an important part of the whole vehicle and also follows the development trend of the whole vehicle electromotion.

At present, the electric drive axle technology of commercial vehicles is increasingly regarded as the important technology of the whole vehicle. The electric drive axle is used as a power source of the whole vehicle, and the performance of the electric drive axle directly influences the power performance, the economy, the trafficability characteristic and the like of the whole vehicle. In order to improve the dynamic property of the whole vehicle, various manufacturers use driving motors with higher power, which undoubtedly increases the cost of the whole vehicle, and the traditional two-gear speed reducer is large in size and weight. In the limited space of the drive axle, the high-power motor and the speed reducer occupy larger arrangement space, and the trafficability of the automobile is influenced.

Meanwhile, in the prior art, a coaxial electric drive axle and a parallel shaft electric drive axle are provided, and the speed reducing mechanism is realized through a gear shifting plectrum, so that the structure is complex and the reliability is low.

Disclosure of Invention

In order to solve the problems, the invention aims to provide an electric drive axle structure with double motors and a working method thereof, and the electric drive axle structure is compact in structure, high in flexibility, simple to install and maintain, capable of being suitable for different operation conditions, and capable of effectively improving the cruising ability of a vehicle.

The invention is realized by the following technical scheme:

the invention discloses an electric drive axle structure with double motors, which comprises a first motor, a second motor, an epicyclic gear train, a driving gear, a driven gear, a differential, a driving half shaft and a brake, wherein the first motor is connected with the second motor through a transmission shaft;

the first motor comprises a first motor stator and a first motor rotor, the second motor comprises a second motor stator and a second motor rotor, and the first motor stator, the first motor rotor, the second motor stator and the second motor rotor are all arranged on the shaft; the epicyclic gear train comprises a gear ring, a planet carrier, a sun gear and a planet gear; the first motor rotor is fixedly connected with the sun gear, the second motor rotor is fixedly connected with the gear ring, and the gear ring is connected with the brake; one side of planet carrier is connected with the planet wheel, and the opposite side is connected with the driving gear, and the driving gear meshes with driven gear, and driven gear is connected with differential mechanism, and differential mechanism is connected with the drive semi-axis.

Preferably, the differential includes a differential case, differential planet gears, and side gears; the driving half shaft comprises a first output half shaft and a second output half shaft; the driven gear is connected with the differential case, the differential case is connected with the differential planetary gear, the differential planetary gear is meshed with the side gear, the side gear is respectively connected with the first output half shaft and the second output half shaft, and the first output half shaft and the second output half shaft are connected to the wheel hub.

Preferably, the differential is a limited slip differential.

Preferably, the first motor and the second motor are both hollow shaft motors.

Preferably, the first motor stator and the second motor stator are symmetrically arranged on the shaft, the first motor stator and the second motor stator are mounted on the stator fixing disc through the connecting block, and the stator fixing disc is connected with the shaft.

Further preferably, the stator fixing disc is made of non-magnetic material.

Preferably, the first motor rotor is connected with the sun gear through a bolt, the second motor rotor is connected with the gear ring through a stud, and the stud is connected with the brake.

Preferably, the first and second electrical machines are axial flux permanent magnet synchronous machines.

The invention discloses a working method of the electric drive bridge structure with the double motors, which comprises the following steps: when the automobile runs at low speed, the gear ring is braked by the brake, the epicyclic train with the degree of freedom of 1 is the epicyclic train at the moment, the power of the first motor is input by the sun gear, is output to the driving gear by the planet carrier after being decelerated by the epicyclic train, the driving gear drives the driven gear, the driven gear transmits the power to the differential mechanism, and the differential mechanism transmits the power to the automobile hub by the driving half shaft;

when the automobile runs at high speed, the brake releases the brake on the gear ring, the epicyclic wheel is a differential gear train with the degree of freedom of 2, the power of the first motor is input by the sun gear, the power of the second motor is input by the gear ring, and is output to the driving gear by the planet carrier after being coupled by the differential gear train, and finally the power is transmitted to the automobile hub.

Preferably, when the automobile runs at a low speed, the system speed reduction ratio is as follows:

the output torque is:

T_H＝i·T_a

the output rotating speed is as follows:

n_H＝n_a/i

wherein n is_aThe rotational speed of the sun gear; n is_HThe rotational speed of the planet carrier; z_aThe number of teeth of the sun gear; z_bThe number of teeth of the gear ring; t is_aIs the output torque of the first motor;

when the automobile runs at high speed, mu is taken_o＝Z_b/Z_a

The output torque is:

T_H＝-(1+μ_o)·T_a＝-(1+μ_o)·T_b/μ_o

the output rotating speed is as follows:

wherein n is_aThe rotational speed of the sun gear; n is_bIs the rotational speed of the gear ring; n is_HThe rotational speed of the planet carrier; t is_bIs the output torque of the second motor; z_aThe number of teeth of the sun gear; z_bThe number of teeth of the gear ring; mu.s_oIs a characteristic parameter of the epicyclic gear train.

Compared with the prior art, the invention has the following beneficial technical effects:

the invention discloses an electric drive axle structure with double motors, which mainly comprises a first motor, a second motor, an epicyclic gear train, a transmission gear system, a differential mechanism, a drive half shaft and a brake, wherein the epicyclic gear train can be switched between a planetary gear train and a differential gear train through the brake; when the first motor and the second motor are driven together, the high rotating speed can be output, the electric drive axle is in a second gear, and the electric drive axle is suitable for the working condition of high power and high rotating speed when an automobile runs at high speed; the running conditions of low-speed large torque and high-speed high power of the automobile can be met. The drive axle has reasonable structural design, convenient use, clear integral structure and convenient installation and later maintenance; the structure is more compact, the weight is lighter, the working efficiency is high, and the high-power-density high-rotation-speed high-smoothness device has high power density; the integrated design improves the packaging flexibility, the electrification degree and the transmission efficiency of the automobile. The traditional power motor has low transmission efficiency, large volume and difficult arrangement, and has improvement space. Traditional integrated form electric drive unsprung mass is big, and axle life reduces by a wide margin, and influences whole car ride comfort, and the operational environment of motor is abominable in addition, influences its life. The drive axle has the advantages of compact structure, simple assembly, light weight, small volume, small occupied space, easy arrangement and high safety performance. Because the clutch and the speed changer are not arranged, the size and the weight of the transmission device are reduced, a larger arrangement space is provided for the arrangement of the power battery, and the cruising ability is effectively increased.

Further, the differential mechanism adopts an antiskid differential mechanism, and can overcome the defect that when a common bevel gear type differential mechanism runs on a bad road surface (muddy road surface, ice and snow road surface and the like) due to the fact that torque is evenly distributed to the left wheel and the right wheel, the driving wheel on one side is in contact with the muddy road surface and the ice and snow road surface to skid (slip) in situ, and the driving wheel on the other side on a good road surface is in a stationary state, so that the passing capacity of the automobile is reduced.

Furthermore, the first motor and the second motor both adopt hollow shaft motors, so that the size is small, the weight is light, and the noise can be obviously reduced.

Furthermore, the first motor stator and the second motor stator are connected through the connecting block, and a distance is reserved between the first motor stator and the second motor stator, so that the magnetic fields of the first motor stator and the second motor stator can be prevented from influencing each other; and the two are arranged symmetrically on the shaft, so that the load on the shaft is uniformly distributed, the rotation is stable, and the noise is low.

Furthermore, the stator fixing disc is made of non-magnetic materials, so that the influence of magnetic fields on the first motor stator and the second motor stator can be further reduced.

Furthermore, the first motor and the second motor are axial flux permanent magnet synchronous motors, and have the advantages of high power density, large peak torque, wide high-efficiency area, and small noise, vibration, size and weight.

The invention discloses a working method of the electric drive bridge structure with the double motors.

Drawings

FIG. 1 is a schematic view of the overall structure of the present invention;

FIG. 2 is a schematic power transmission path of the present invention with the transaxle in first gear;

fig. 3 is a schematic diagram of a power transmission route when the transaxle of the present invention is in second gear.

In the figure: 1. a first motor stator; 2. a first motor rotor; 3. a second motor stator; 4. a second motor rotor; 5. a ring gear; 6. a planet wheel; 7. a planet carrier; 8. a sun gear; 9. a driving gear; 10. a driven gear; 11. a differential housing; 12. a differential planetary gear; 13. a half shaft gear; 14. a first output half shaft; 15. a shaft; 16. a second output half shaft; 17. and a brake.

Detailed Description

The invention is described in further detail below with reference to the following figures and specific embodiments:

fig. 1 is a schematic view of the overall structure of an electric drive axle structure with two motors according to the present invention, which includes a first motor, a second motor, an epicyclic gear train, a driving gear 9, a driven gear 10, a differential, a driving half shaft and a brake 17;

the first motor comprises a first motor stator 1 and a first motor rotor 2, the second motor comprises a second motor stator 3 and a second motor rotor 4, and the first motor stator 1, the first motor rotor 2, the second motor stator 3 and the second motor rotor 4 are sequentially arranged on the shaft 15 from left to right; the epicyclic gear train comprises a gear ring 5, a planet carrier 7, a sun wheel 8 and a planet wheel 6; the first motor rotor 2 is fixedly connected with the sun gear 8, the second motor rotor 4 is fixedly connected with the gear ring 5, and the gear ring 5 is connected with the brake 17; one side of the planet carrier 7 is connected with the planet wheel 6, the other side is connected with the driving gear 9, the driving gear 9 is meshed with the driven gear 10, the driven gear 10 is connected with the differential mechanism, and the differential mechanism is connected with the driving half shaft.

The differential includes a differential case 11, differential planetary gears 12, and side gears 13; the drive half shafts include a first output half shaft 14 and a second output half shaft 16; the driven gear 10 is connected to a differential case 11, the differential case 11 is connected to a differential planetary gear 12, the differential planetary gear 12 is meshed with a side gear 13, the side gear 13 is connected to a first output half shaft 14 and a second output half shaft 16, respectively, and the first output half shaft 14 and the second output half shaft 16 are connected to a wheel hub. The first output half shaft 14, the second output half shaft 16 and the differential are all located in a drive axle housing assembly, and the two half shaft sleeves are fixedly welded on the axle housing assembly.

The first motor rotor 2 is connected with the sun gear 8 through a bolt, the second motor rotor 4 is connected with the gear ring 5 through a stud, and the stud is connected with the brake 17.

The driving gear 9 and the driven gear 10 are cylindrical gears.

In a preferred embodiment of the invention, the differential is an anti-skid differential.

In a preferred embodiment of the present invention, the first motor and the second motor are both hollow shaft motors.

In a preferred embodiment of the present invention, the first motor stator 1 and the second motor stator 3 are symmetrically arranged on the shaft 15, the first motor stator 1 and the second motor stator 3 are mounted on the stator fixing disc through the connecting block, the stator fixing disc is connected with the shaft 15 to form a three-disc structure with two rotors on two sides and two stators in the middle. Preferably, the stator fixing disc is made of non-magnetic materials.

In a preferred embodiment of the invention, the first motor and the second motor are axial flux permanent magnet synchronous motors, and permanent magnets are arranged on the rotors to replace excitation windings, so that copper loss is reduced, and high-efficiency operation of the motors is ensured.

The electric drive axle structure with the double motors is characterized in that:

as shown in fig. 2, when the automobile runs at a low speed, the gear ring 5 is braked by the brake 17, at this time, the epicyclic train is a planetary train with a degree of freedom of 1, the power of the first motor is input by the sun gear 8, is reduced by the planetary train and is output to the driving gear 9 by the planet carrier, the driving gear 9 drives the driven gear 10, the driven gear 10 transmits the power to the differential mechanism, and the differential mechanism transmits the power to the automobile hub through the driving half shaft;

under this operating mode, system's reduction ratio is:

the output torque is:

T_H＝i·T_a

the output rotating speed is as follows:

n_H＝n_a/i

wherein n is_aThe rotational speed of the sun gear 8; n is_HThe rotational speed of the planet carrier 7; z_aThe number of teeth of the sun gear 8; z_bThe number of teeth of the ring gear 5; t is_aIs the output torque of the first motor;

as shown in fig. 3, when the automobile is running at a high speed, the brake 17 releases the brake on the gear ring 5, at this time, the epicyclic gear is a differential gear train with a degree of freedom of 2, the power of the first motor is input by the sun gear 8, the power of the second motor is input by the gear ring 5, and after being coupled by the differential gear train, the power is output to the driving gear 9 by the planet carrier, and finally the power is transmitted to the automobile hub.

In this condition, take mu_o＝Z_b/Z_a

The output torque is:

T_H＝-(1+μ_o)·T_a＝-(1+μ_o)·T_b/μ_o

the output rotating speed is as follows:

wherein n is_aThe rotational speed of the sun gear 8; n is_bThe rotational speed of the ring gear 5; n is_HThe rotational speed of the planet carrier 7; t is_bIs the output torque of the second motor; z_aThe number of teeth of the sun gear 8; z_bThe number of teeth of the ring gear 5; mu.s_oIs a characteristic parameter of the epicyclic gear train.

The design of the differential gear train has a crucial influence on the power performance and the economical efficiency of the extended range type commercial vehicle driven by the motor system. The driving motor can work in a high-efficiency area for more time by selecting a proper speed ratio, so that the economical efficiency and the dynamic property of the whole vehicle can be improved.

According to the analysis, the system can realize two working modes of the independent driving of the first motor and the joint driving of the first motor and the second motor. When increasing the characteristic parameter mu of the NGW planetary gear mechanism_oThe reduction ratio of the first operating mode can be increased, so that the torque output at low speed of the drive motor system can be increased. However, the characteristic parameter μ of the NGW planetary gear_oAnd not too large, when the driving motor is in the second working mode, the ratio of the output torques of the first motor and the second motor is fixed 1/mu_oIf μ_oToo large a value results in too large an output torque of the second motor, making the motor design difficult.

It should be noted that the embodiment described in the example is only a preferred embodiment of the present invention, and it will be apparent to those skilled in the art that several modifications and improvements can be made without departing from the principle of the present invention, and these modifications and improvements should be construed as the protection scope of the present invention.