Dual-motor four-gear gearbox and gear shifting control method thereof

Abstract

A double-motor four-gear speed changing box comprises two motors and a speed changing assembly with a two-gear speed changing function, and is characterized by further comprising a double-planet-row structure and a braking assembly installed in the double-planet-row structure, the speed changing assembly is of a parallel shaft structure, the motors are connected with the input end of the speed changing assembly, the double-planet-row structure is connected with the output end of the speed changing assembly, and the braking assembly is installed in the double-planet-row structure. The double-planet-row structure forms two-gear speed ratio switching along with control of the brake assembly. The low-speed high-torque and high-speed efficient driving requirements of a vehicle are accurately matched, the coverage range of the efficient interval of the motor is widened, the axial space layout and weight of the gearbox are reduced, the power density of output torque is improved, the transmission stability is improved, the torque connection efficiency between gears is improved, the gear shifting impact is reduced, and the driving experience is improved; and the robustness of the speed control system is improved. The invention further provides a gear shifting control method of the double-motor four-gear gearbox.

Description

Technical Field

[0001] The present invention relates to a dual-motor four-speed transmission and a shift control method thereof, belonging to the technical field of pure electric transmissions. Background Art

[0002] As electric vehicles continue to demand more efficient and multi-scenario power output, the high cost of a single high-power motor and its low efficiency under low-load conditions often lead to high energy consumption and unsatisfactory power performance. Therefore, single-motor electric drive axle solutions have significant limitations. With the continuous advancement of technology, electric drive axles with dual-motor architectures have gradually become a research hotspot. By coordinating two relatively small-power motors, not only can the system cost be reduced, but also the motors can be operated more often in the high-efficiency working area through precise speed ratio configuration, thereby significantly improving the vehicle's economy and driving experience. In the field of dual-motor electric drive axles, planetary gear mechanisms and parallel shaft structures are widely used to achieve flexible coupling of motors and intelligent distribution of power, and clutches are used to achieve gear control. However, the transmission structure used in existing multi-speed electric drive systems has problems such as volume redundancy, power interruption during gear shifting, or limited torque carrying capacity. Especially in the field of high-performance vehicles, the dual-motor coupled drive and multi-speed coordinated drive solutions have the following problems: 1. The parallel shaft structure with multiple gear settings takes up a lot of axial space, is heavy, has high mechanical losses, and has low power density.

[0003] 2. The torque diversion capability is poor, the single-stage gear has a large load and wears quickly, affecting the transmission stability.

[0004] 3. The connection between multiple gear torques is not smooth, causing gear shift shock and reducing the driving experience. Summary of the Invention

[0005] The dual-motor four-speed transmission and its shift control method provided by the present invention accurately match the vehicle's low-speed, high-torque and high-speed, high-efficiency drive requirements, broaden the coverage of the motor's high-efficiency range, reduce the transmission's axial spatial layout and weight, increase the power density of the output torque, improve transmission stability, improve the torque connection efficiency between gears, reduce shifting shock, improve the driving experience, and enhance the robustness of the transmission system.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is: A dual-motor four-speed transmission includes two motors and a transmission assembly with a two-speed shifting function. The characteristics are: it also includes a dual planetary gear structure and a brake assembly installed in the dual planetary gear structure. The transmission assembly is a parallel shaft structure. The motor is connected to the input end of the transmission assembly, and the dual planetary gear structure is connected to the output end of the transmission assembly. The dual planetary gear structure forms a two-speed ratio switch under the control of the brake assembly.

[0007] Preferably, the dual planetary gear structure includes a first planetary gear and a second planetary gear, the ring gear of the first planetary gear is fixedly connected to the ring gear of the second planetary gear, the output end of the speed change assembly is connected to the ring gear of the first planetary gear, the planet carrier of the first planetary gear is fixedly connected to the sun gear of the second planetary gear, and the brake assembly controls the sun gear of the first planetary gear or the sun gear of the second planetary gear to be fixed.

[0008] Preferably, the speed change assembly includes an input shaft connected to the motor shaft end, an intermediate shaft arranged parallel to the two input shafts, a low-speed driving gear coaxially fixed on the input shaft, a high-speed driving gear coaxially fixed on the input shaft, a low-speed driven gear meshing with the low-speed driving gear, a high-speed driven gear meshing with the high-speed driving gear, and a shift gear sleeve axially slidably assembled on the intermediate shaft, the low-speed driven gear and the high-speed driven gear are respectively rotatably mounted on the intermediate shaft, the shift gear sleeve is located between the low-speed driven gear and the high-speed driven gear, the shift gear sleeve slides to the left and combines with the low-speed driven gear, and slides to the right and combines with the high-speed driven gear, and the intermediate shaft is coaxially connected to the ring gear of the first planetary row.

[0009] Preferably, the first planetary row includes a first sun gear, a first planetary gear meshed with the first sun gear, a first planetary carrier mounted on the first planetary gear, and a first ring gear whose inner ring is meshed with the first planetary gear; the second planetary row includes a second sun gear, a second planetary gear meshed with the second sun gear, a second planetary carrier mounted on the second planetary gear, and a second ring gear whose inner ring is meshed with the second planetary gear; the first ring gear and the second ring gear are fixedly connected, the intermediate shaft is connected to the first ring gear, the first planetary carrier is fixedly connected to the second sun gear, and the brake assembly includes a first brake mounted on the first sun gear and a second brake mounted on the second sun gear.

[0010] Preferably, the intermediate shaft, the first ring gear and the second ring gear are integrally formed, and the output shaft is integrally formed on the second planetary carrier.

[0011] The above-mentioned shift control method for the dual-motor four-speed transmission is characterized by: By controlling the speed change assembly and the brake assembly, the four-speed power output of the dual-motor four-speed transmission is achieved; When the transmission assembly forms the first gear power and the brake assembly controls the double planetary gear structure to form the second gear ratio, the first gear power output of the dual-motor four-speed transmission is formed; When the transmission assembly forms the first gear power and the brake assembly controls the double planetary gear structure to form the first gear speed ratio, the second gear power output of the dual-motor four-speed transmission is formed; When the transmission assembly forms the second-gear power and the brake assembly controls the double planetary gear structure to form the second-gear speed ratio, the third-gear power output of the dual-motor four-gear transmission is formed; When the transmission assembly forms the second-gear power and the brake assembly controls the double planetary gear structure to form the first-gear speed ratio, the fourth-gear power output of the dual-motor four-gear transmission is formed; Preferably, "the speed change assembly forms a first gear power" means that the shift sleeve slides to the left and engages with the low-gear driven gear; "the speed change assembly forms a second gear power" means that the shift sleeve slides to the right and engages with the high-gear driven gear.

[0012] Preferably, "the double planetary gear structure forms a second gear ratio" means that the second brake is activated to fix the first planet carrier and the second sun gear, the intermediate shaft drives the first ring gear and the second ring gear to rotate, and the second ring gear drives the second planet carrier to rotate to output power; "Double planetary gear structure forming a first gear ratio" means that the first brake is activated to fix the first sun gear, the intermediate shaft drives the first ring gear and the second ring gear to rotate, the power of the second ring gear is transmitted to the second planetary carrier, and the power of the first ring gear is also transmitted to the second planetary carrier through the first planetary carrier and the second sun gear. The power is then combined and output on the second planetary carrier.

[0013] The beneficial effects of the present invention are: The dual-motor four-speed gearbox of the present invention has two motors connected to the input end of the speed change assembly respectively, and the dual planetary gear structure is connected to the output end of the speed change assembly. The speed change assembly with a parallel shaft structure couples the power of the two motors and forms two-speed power transmission to the dual planetary gear structure. The dual planetary gear structure forms a two-speed ratio switching under the control of the brake assembly. The two-speed power of the speed change assembly is combined with the two-speed ratio of the dual planetary gear structure, which not only forms a four-speed power output of the gearbox, but also accurately matches the low-speed high-torque and high-speed and high-efficiency driving requirements of the vehicle, broadens the coverage of the motor's high-efficiency range, and utilizes the planetary gears to achieve a high-speed and high-efficiency driving performance. The compact gearbox structure and large speed ratio reduce the axial space layout and weight of the gearbox, reduce mechanical losses during transmission, and improve the power density of output torque; the dual planetary gearbox structure effectively increases the torque diversion capability, reduces the load on single-stage gears, and improves transmission stability; the brake assembly is used to form a two-speed ratio of the dual planetary gearbox structure, forming a coordinated control of parallel shaft structure shifting and planetary gearbox brake shifting, improving the torque connection efficiency between gears, reducing shifting shock, and improving driving experience. The redundant design formed by the dual motors supports the limp mode under single motor failure, and improves the robustness of the transmission system. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 Schematic diagram of the transmission structure of a dual-motor four-speed gearbox in a specific implementation.

[0015] Figure 2 Schematic diagram of the transmission structure of a dual-motor four-speed gearbox when forming first-gear power.

[0016] Figure 3 Schematic diagram of the transmission structure of the dual-motor four-speed gearbox when forming second-gear power.

[0017] Figure 4 Schematic diagram of the transmission structure of a dual-motor four-speed gearbox when forming three-speed power.

[0018] Figure 5 Schematic diagram of the transmission structure of a dual-motor four-speed gearbox when forming four-speed power. DETAILED DESCRIPTION

[0019] The following combination Figures 1 to 5 The embodiments of the present invention are described in detail.

[0020] A dual-motor four-speed transmission comprises two motors 1 and a transmission assembly 2 with a two-speed shifting function, characterized in that it further comprises a dual planetary gear structure 3 and a brake assembly 4 installed in the dual planetary gear structure 3. The transmission assembly 2 is a parallel axis structure. The motor 1 is connected to the input end of the transmission assembly 2, and the dual planetary gear structure 3 is connected to the output end of the transmission assembly 3. The dual planetary gear structure 3 forms a two-speed ratio switch under the control of the brake assembly 4.

[0021] In the dual-motor four-speed gearbox described above, the two motors 1 are respectively connected to the input end of the speed change component 2, and the dual planetary gear structure 3 is connected to the output end of the speed change component 2. The speed change component 2 with a parallel shaft structure couples the power of the two motors 1 and forms two-speed power transmission to the dual planetary gear structure 3. The dual planetary gear structure 3 forms a two-speed ratio switching under the control of the brake component 4. The two-speed power of the speed change component 2 is combined with the two-speed ratio of the dual planetary gear structure 3, which not only forms a four-speed power output of the gearbox, but also accurately matches the vehicle's low-speed high-torque and high-speed and high-efficiency driving requirements, and broadens the coverage of the motor's high-efficiency range. The compact structure and large speed ratio of the planetary gearbox are utilized to reduce the axial space layout and weight of the gearbox, reduce mechanical losses during transmission, and improve the power density of the output torque; the dual planetary gearbox structure 3 effectively increases the torque diversion capability, reduces the load on single-stage gears, and improves transmission stability; the brake assembly 4 is used to form a two-speed ratio of the dual planetary gearbox structure, forming a coordinated control of the parallel shaft structure shifting and the planetary gearbox brake shifting, improving the torque connection efficiency between gears, reducing the shifting shock, and improving the driving experience. The dual motors form a redundant design to support the limp mode under single motor failure, thereby improving the robustness of the transmission system.

[0022] The dual planetary gear structure 3 includes a first planetary gear set 5 and a second planetary gear set 6. The ring gear of the first planetary gear set 5 is fixedly connected to the ring gear of the second planetary gear set 6. The output end of the speed change assembly 2 is connected to the ring gear of the first planetary gear set 5. The planet carrier of the first planetary gear set 5 is fixedly connected to the sun gear of the second planetary gear set 6. The brake assembly 4 controls the fixation of the sun gear of the first planetary gear set 5 or the sun gear of the second planetary gear set 6. The ring gears of the two planetary gear sets are fixedly connected as a whole, and the ring gears serve as the input end of the dual planetary gear set 3. The output end of the speed change assembly 2 drives the ring gears to move and transmit power to the dual planetary gear set 3. The brake assembly can fix the sun gear of the first planetary gear set 5 or the sun gear of the second planetary gear set 6, thereby changing the speed ratio of the dual planetary gear set 3, so that the dual planetary gear set 3 can form a two-speed ratio switch under the control of the brake assembly 4.

[0023] The speed change assembly 2 includes an input shaft 21 connected to the shaft end of the motor 1, an intermediate shaft 22 arranged parallel to the two input shafts 21, a low-speed driving gear 23 coaxially fixed to the input shaft 21, a high-speed driving gear 24 coaxially fixed to the input shaft 21, a low-speed driven gear 25 meshing with the low-speed driving gear 23, a high-speed driven gear 26 meshing with the high-speed driving gear 24, and a shift sleeve 27 axially slidably assembled on the intermediate shaft 22. The low-speed driven gear 25 and the high-speed driven gear 26 are respectively rotatably mounted on the intermediate shaft 22. The shift sleeve 27 is located between the low-speed driven gear 25 and the high-speed driven gear 26. The shift sleeve 27 slides to the left to engage with the low-speed driven gear 25 and slides to the right to engage with the high-speed driven gear 26. The intermediate shaft 22 is coaxially connected to the ring gear of the first planetary row 5. In the initial state, the shift sleeve 27 is in a neutral position between the low-speed driven gear 25 and the high-speed driven gear 26. Since both the low-speed driven gear 25 and the high-speed driven gear 26 are rotatably mounted on the intermediate shaft 22, the shift sleeve 27 cannot transmit the power of the input shaft to the intermediate shaft 22 when it is in neutral. When the shift sleeve 27 is engaged with the low-speed driven gear 25, the power of the motor is transmitted to the intermediate shaft 22 via the input shaft 21, the low-speed driving gear 23, the low-speed driven gear 25, and the shift sleeve 27. The intermediate shaft 22 transmits the power to the double planetary gear set 3. When the shift sleeve 27 is engaged with the high-speed driven gear 26, the power of the motor is transmitted to the intermediate shaft 22 via the input shaft 21, the high-speed driving gear 24, the high-speed driven gear 26, and the shift sleeve 27. The intermediate shaft 22 transmits the power to the double planetary gear set 3. Therefore, two gears can be formed on the intermediate shaft 22 and the power is transmitted to the double planetary gear set 3.

[0024] Among them, the first planetary row 5 includes a first sun gear 51, a first planetary gear meshed with the first sun gear 51, a first planetary carrier 52 mounted on the first planetary gear, and a first ring gear 53 whose inner ring is meshed with the first planetary gear. The second planetary row 6 includes a second sun gear 61, a second planetary gear meshed with the second sun gear 51, a second planetary carrier 62 mounted on the second planetary gear, and a second ring gear 63 whose inner ring is meshed with the second planetary gear. The first ring gear 53 and the second ring gear 63 are fixedly connected, the intermediate shaft 22 is connected to the first ring gear 53, the first planetary carrier 52 is fixedly connected to the second sun gear 61, and the brake assembly 4 includes a first brake 41 mounted on the first sun gear 51 and a second brake 42 mounted on the second sun gear 64.When the first brake 41 is activated, the first sun gear 51 is fixed, and the power of the intermediate shaft 22 is transmitted to the first ring gear 53 and the second ring gear 63. The power of the first ring gear 53 is transmitted to the second planetary carrier via the first planetary row and the second planetary row. The power of the second ring gear 63 is transmitted to the second planetary carrier via the second planetary row. The power is combined and outputted at the second planetary carrier, forming the first gear ratio of the double planetary row structure 3; when the second brake 42 is activated, the second sun gear 61 is fixed, that is, the first planetary carrier is fixed, the first planetary row does not transmit power, and only the second planetary row is transmitted. The power transmission of the intermediate shaft 22 is transmitted to the second planetary carrier by the second ring gear 63, forming the second gear ratio of the double planetary row structure 3. The value of the first gear ratio is smaller than the value of the second gear ratio. When the planetary gear structure 3 forms a first gear ratio, the output speed is high and the torque is small. When the double planetary gear structure 3 forms a second gear ratio, the output speed is low and the torque is large. When the meshing gear sleeve 27 is combined with the low-speed driven gear 25 and the second brake is activated, the power of the motor 11 is transmitted to the intermediate shaft 22 through the input shaft 21, the low-speed driving gear 23, the low-speed driven gear 25, and the meshing gear sleeve 27. The intermediate shaft 22 drives the first ring gear 51 and the second ring gear 61. The second ring gear 61 drives the second planetary carrier 62 to move through the second planetary gear. The second planetary carrier 62 outputs power to form the first gear power of the gearbox. When the meshing gear sleeve 27 is combined with the low-speed driven gear 25 and the first brake is activated, the power of the motor 11 is transmitted to the intermediate shaft 22 through the input shaft 21, the low-speed driving gear 23, the low-speed driven gear 25, and the meshing gear sleeve 27. The intermediate shaft 22 drives the first ring gear 51 and the second ring gear 61. The second ring gear 61 drives the second planetary carrier 62 to move through the second planetary gear. The second planetary carrier 62 outputs power to form the first gear power of the gearbox. The gear 23, the low-speed driven gear 25, and the meshing gear sleeve 27 are transmitted to the intermediate shaft 22, and the intermediate shaft 22 drives the first ring gear 53 and the second ring gear 63 to move. The power of the first ring gear 51 is transmitted to the second planetary carrier 62 through the first planetary carrier 52, the second sun gear 61, and the second planetary gear. The power of the second ring gear 63 is transmitted to the second planetary carrier 62 through the second planetary gear. The power is combined and outputted at the second planetary carrier 62 to form the second gear power of the transmission. When the meshing gear sleeve 27 is engaged with the high-speed driven gear 26 and the second brake 42 is activated, the power of the motor 11 is transmitted to the intermediate shaft 22 through the input shaft 21, the high-speed driving gear 24, the high-speed driven gear 26, and the meshing gear sleeve 27. The intermediate shaft 22 drives the first ring gear 51 and the second ring gear. The second ring gear 61 drives the second planetary carrier 62 to move through the second planetary gear, and the second planetary carrier 62 outputs power to form the third gear power of the transmission; when the meshing sleeve is engaged with the high-speed driven gear 26 and the first brake is activated, the power of the motor 11 is transmitted to the intermediate shaft 22 through the input shaft 21, the high-speed driving gear 24, the high-speed driven gear 26, and the meshing sleeve 27. The intermediate shaft 22 drives the first ring gear 53 and the second ring gear 63 to move. The power of the first ring gear 51 is transmitted to the second planetary carrier 62 through the first planetary gear 52, the second sun gear 61, and the second planetary gear. The power of the second ring gear 63 is transmitted to the second planetary carrier 62 through the second planetary gear. The power is combined and output at the second planetary carrier 62 to form the fourth gear power of the transmission.

[0025] The intermediate shaft 22, the first ring gear 53 and the second ring gear 53 are integrally formed, and the output shaft 7 is integrally formed on the second planet carrier 62. This improves the stability and reliability of the dual planetary gear structure 3 and effectively reduces maintenance costs.

[0026] The present invention also protects the above-mentioned shift control method of the dual-motor four-speed transmission, which is characterized by: By controlling the speed change component 2 and the brake component 4, the four-speed power output of the dual-motor four-speed transmission is achieved; When the transmission assembly 2 forms the first gear power and the brake assembly 4 controls the double planetary gear structure 3 to form the second gear speed ratio, the first gear power output of the dual-motor four-speed transmission is formed; When the transmission assembly 2 forms the first gear power and the brake assembly 4 controls the double planetary gear structure 3 to form the first gear speed ratio, the second gear power output of the dual-motor four-speed transmission is formed; When the transmission assembly 2 forms the second-gear power and the brake assembly 4 controls the dual planetary gear structure 3 to form the second-gear speed ratio, the third-gear power output of the dual-motor four-gear transmission is formed; When the speed change assembly 2 forms the second gear power and the brake assembly 4 controls the double planetary gear structure 3 to form the first gear speed ratio, the fourth gear power output of the dual-motor four-speed transmission is formed; Since the speed ratio is proportional to the torque and inversely proportional to the speed, the larger the speed ratio, the greater the torque and the lower the speed. The value of the first gear speed ratio of the dual planetary gear structure 3 is smaller than the value of its second gear speed ratio. When the dual planetary gear structure 3 forms the first gear speed ratio, the output speed is higher and the torque is lower. When the second gear speed ratio is formed, the output speed is lower and the torque is higher. Therefore, when the transmission component 2 forms the first gear power and the dual planetary gear structure 3 forms the second gear speed ratio, the first gear power output of the dual-motor four-speed transmission is formed, which meets the driving requirements of high torque escape under heavy-load and harsh working conditions; when the transmission component 2 forms the first gear power and the dual planetary gear structure 3 forms the first gear speed ratio, the dual-motor four The second-gear power output of the gearbox meets the driving requirements of high-speed driving under heavy-load conditions; when the speed change component 2 forms the second-gear power and the double planetary gear structure 3 forms the second-gear speed ratio, the third-gear power output of the dual-motor four-gear gearbox is formed, which meets the driving requirements of fast passing under light-load and harsh working conditions; when the speed change component forms the second-gear power and the double planetary gear structure forms the first-gear speed ratio, the fourth-gear power output of the dual-motor four-gear gearbox is formed, which meets the driving requirements of high-speed driving under light-load conditions; the fourth-gear power output of the gearbox is formed, which accurately matches the vehicle's low-speed high-torque and high-speed and high-efficiency driving requirements, and broadens the coverage of the motor's high-efficiency range.

[0027] Here, "speed transmission assembly 2 forms first gear" means that the shift sleeve 37 slides leftward and engages with the low-speed driven gear 25; "speed transmission assembly 2 forms second gear" means that the shift sleeve 27 slides rightward and engages with the high-speed driven gear 26. When the shift sleeve 27 engages with the low-speed driven gear 25, the power of the motor is transmitted via the input shaft 21, the low-speed driving gear 23, the low-speed driven gear 25, and the shift sleeve 27 to the intermediate shaft 22. The intermediate shaft 22 transmits the power to the dual planetary gear set 3. When the shift sleeve 27 engages with the high-speed driven gear 26, the power of the motor is transmitted via the input shaft 21, the high-speed driving gear 24, the high-speed driven gear 26, and the shift sleeve 27 to the intermediate shaft 22. The intermediate shaft 22 transmits the power to the dual planetary gear set 3. Therefore, two power gears are formed on the intermediate shaft 22 and transmitted to the dual planetary gear set 3.

[0028] Preferably, "the double planetary gear structure 3 forms a second gear ratio" means that the second brake 42 is activated to fix the first planet carrier 52 and the second sun gear 61, the intermediate shaft 22 drives the first ring gear 53 and the second ring gear 63 to rotate, and the second ring gear 63 drives the second planet carrier 62 to rotate to output power; "The double planetary gear structure 3 forms a first gear ratio" means that the first brake 41 is activated to fix the first sun gear 51, the intermediate shaft 22 drives the first ring gear 53 and the second ring gear 63 to rotate, the power of the second ring gear 63 is transmitted to the second planetary carrier 62, and the power of the first ring gear 53 is also transmitted to the second planetary carrier 62 via the first planetary carrier 52 and the second sun gear 61. The power is then combined and output on the second planetary carrier.

[0029] When the first brake 41 is activated, the first sun gear 51 is fixed, and the power of the intermediate shaft 22 is transmitted to the first ring gear 53 and the second ring gear 63. The power of the first ring gear 53 is transmitted to the second planetary carrier 62 through the first planetary carrier 52 and the second sun gear 61. The power of the second ring gear 63 is also transmitted to the second planetary carrier 62. The power is merged and output at the second planetary carrier, forming the first gear ratio of the double planetary gear structure 3; when the second brake 42 is activated, the second sun gear 61 is fixed, that is, the first planetary carrier 52 is fixed, the first planetary gear does not transmit power, only the second planetary gear is transmitted, and the power transmission of the intermediate shaft 22 is transmitted from the second ring gear 63 to the second planetary carrier 62, forming the second gear ratio of the double planetary gear structure 3. The value of the first gear ratio is smaller than the value of the second gear ratio. When the double planetary gear structure 3 forms the first gear ratio, its output speed is high and the torque is small. When the double planetary gear structure 3 forms the second gear ratio The output speed is low and the torque is large. Therefore, when the speed transmission component 2 forms the first gear power and the dual planetary gear structure 3 forms the second gear speed ratio, the first gear power of the dual-motor four-speed transmission is formed; when the speed transmission component 2 forms the first gear power and the dual planetary gear structure 3 forms the first gear speed ratio, the second gear power of the dual-motor four-speed transmission is formed, and the speed of the second gear power is higher than the first gear power but the torque is lower than the first gear power; when the speed transmission component 2 forms the second gear power and the dual planetary gear structure 3 forms the second gear speed ratio, the third gear power of the dual-motor four-speed transmission is formed, and the speed of the third gear power is higher than the second gear power but the torque is lower than the second gear power; when the speed transmission component forms the second gear power and the dual planetary gear structure forms the first gear speed ratio, the fourth gear power of the dual-motor four-speed transmission is formed, and the speed of the fourth gear power is higher than the third gear power but the torque is lower than the third gear power, which accurately matches the vehicle's low-speed high-torque and high-speed and high-efficiency driving requirements, and broadens the coverage of the motor's high-efficiency range.

[0030] The above fully describes the technical solutions of the embodiments of the present invention in conjunction with the accompanying drawings. It should be noted that the embodiments described are only part of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

Claims

1. A dual-motor four-speed gearbox, comprising two motors and a gearshift assembly with a two-speed shift function, characterized in that: It also includes a double planetary gear structure and a brake assembly installed in the double planetary gear structure. The speed change assembly is a parallel shaft structure. The motor is connected to the input end of the speed change assembly, and the double planetary gear structure is connected to the output end of the speed change assembly. The double planetary gear structure forms a two-speed ratio switch under the control of the brake assembly.

2. The dual-motor four-speed gearbox according to claim 1, characterized in that: The dual planetary gear structure includes a first planetary gear and a second planetary gear. The ring gear of the first planetary gear is fixedly connected to the ring gear of the second planetary gear. The output end of the speed change assembly is connected to the ring gear of the first planetary gear. The planet carrier of the first planetary gear is fixedly connected to the sun gear of the second planetary gear. The brake assembly controls the sun gear of the first planetary gear or the sun gear of the second planetary gear to be fixed.

3. The dual-motor four-speed gearbox according to claim 2, characterized in that: The speed change assembly includes an input shaft connected to the motor shaft end, an intermediate shaft arranged parallel to the two input shafts, a low-speed driving gear coaxially fixed on the input shaft, a high-speed driving gear coaxially fixed on the input shaft, a low-speed driven gear meshing with the low-speed driving gear, a high-speed driven gear meshing with the high-speed driving gear, and a shift gear sleeve slidably assembled on the intermediate shaft along the axial direction. The low-speed driven gear and the high-speed driven gear are respectively rotatably mounted on the intermediate shaft. The shift gear sleeve is located between the low-speed driven gear and the high-speed driven gear. The shift gear sleeve slides to the left to engage with the low-speed driven gear and slides to the right to engage with the high-speed driven gear. The intermediate shaft is coaxially connected to the ring gear of the first planetary gear row.

4. The dual-motor four-speed gearbox according to claim 2, characterized in that: The first planetary row includes a first sun gear, a first planetary gear meshed with the first sun gear, a first planetary carrier mounted on the first planetary gear, and a first ring gear whose inner ring is meshed with the first planetary gear. The second planetary row includes a second sun gear, a second planetary gear meshed with the second sun gear, a second planetary carrier mounted on the second planetary gear, and a second ring gear whose inner ring is meshed with the second planetary gear. The first ring gear and the second ring gear are fixedly connected, the intermediate shaft is connected to the first ring gear, the first planetary carrier is fixedly connected to the second sun gear, and the brake assembly includes a first brake mounted on the first sun gear and a second brake mounted on the second sun gear.

5. The dual-motor four-speed gearbox according to claim 3, characterized in that: The intermediate shaft, the first ring gear and the second ring gear are integrally formed, and the output shaft is integrally formed on the second planet carrier.

6. The shift control method of a dual-motor four-speed transmission according to any one of claims 1 to 5, characterized in that: By controlling the speed change assembly and the brake assembly, the four-speed power output of the dual-motor four-speed transmission is achieved; When the transmission assembly forms the first gear power and the brake assembly controls the double planetary gear structure to form the second gear ratio, the first gear power output of the dual-motor four-speed transmission is formed; When the transmission assembly forms the first gear power and the brake assembly controls the double planetary gear structure to form the first gear speed ratio, the second gear power output of the dual-motor four-speed transmission is formed; When the transmission assembly forms the second-gear power and the brake assembly controls the double planetary gear structure to form the second-gear speed ratio, the third-gear power output of the dual-motor four-gear transmission is formed; When the transmission assembly forms the second gear power and the brake assembly controls the double planetary gear structure to form the first gear speed ratio, the fourth gear power output of the dual-motor four-speed transmission is formed.

7. The shift control method of a dual-motor four-speed transmission according to claim 6, characterized in that: "The speed change assembly forms first gear power" means that the shift gear sleeve slides to the left and engages with the low-gear driven gear; "the speed change assembly forms second gear power" means that the shift gear sleeve slides to the right and engages with the high-gear driven gear.

8. The shift control method of a dual-motor four-speed transmission according to claim 7, characterized in that: "Dual planetary gear structure forming second gear ratio" means that the second brake is activated to fix the first planet carrier and the second sun gear, the intermediate shaft drives the first and second ring gears to rotate, and the second ring gear drives the second planet carrier to rotate, outputting power; "Dual planetary gear structure forming a first gear ratio" means that the first brake is activated to fix the first sun gear, the intermediate shaft drives the first ring gear and the second ring gear to rotate, the power of the second ring gear is transmitted to the second planetary carrier, and the power of the first ring gear is also transmitted to the second planetary carrier via the first planetary carrier and the second sun gear. The power is then combined and outputted on the second planetary carrier.

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