Commercial vehicle double-axle hybrid power system and working method thereof

Abstract

The invention discloses a commercial vehicle double-axle hybrid power system and a working method thereof, and belongs to the technical field of vehicle power systems. The system comprises a clutch, an intermediate axle hybrid transmission assembly, a first differential mechanism and a rear axle two-gear electric drive axle. The intermediate axle hybrid transmission assembly comprises a generator sliding sleeve, a generator, a first motor and a gear shifting system; the clutch is connected to the generator sliding sleeve and the driving assembly. A generator driven wheel is arranged on an output shaft of the driving assembly; the generator driven wheel is meshed with the generator output wheel; the generator output wheel is connected to the generator; the motor sliding sleeve is provided with two gears; a motor driven wheel is arranged on the input shaft; the motor driven wheel is meshed with a motor output wheel, and the motor output wheel is connected with a first motor; the other end of the input shaft is connected with a first differential through a gear shifting system, and the two sides of the first differential are connected with wheels respectively.

Description

Technical Field

[0001] The present invention belongs to the technical field of vehicle power systems, and relates to a dual-bridge hybrid power system for commercial vehicles and a working method thereof. Background Art

[0002] In the field of commercial vehicles, rapid product upgrades and technological innovations are currently underway. From traditional internal combustion engines to electric motors, and from gasoline / diesel to batteries, new energy technologies are also widely applied in the development of commercial vehicle products. With the increasingly strict laws and regulations and the maturity of new technologies, the proportion of new energy products in the commercial vehicle field is also increasing rapidly. At present, the main technical routes of new energy commercial vehicles include pure electric and hybrid. Pure electric products are mainly suitable for medium and short-distance working conditions with charging conditions, while hybrid products are more suitable for long-distance, non-fixed charging, and complex driving conditions. Currently, commercial vehicle OEMs and power system supporting manufacturers at home and abroad have launched hybrid systems with various architectures. Considering the wide applicability of products, P2 and PS architectures are mainly used, focusing on different user requirements for power performance and economy. Some manufacturers improve the smoothness of the whole vehicle by adding P1, P2.5, P3 motors, etc., to ensure uninterrupted power.

[0003] Traditional commercial vehicle transmissions mostly use clutches and multi-gear parallel shaft structures for power transmission. The advantages are simple structure and high transmission efficiency, but the overall size and weight of the multi-gear box are relatively large, there is power interruption during gear shifting, there is a jerky feeling in the cooperation between the clutch and the engine, the engine efficiency is low, the high-efficiency area is small, and the fuel consumption is high. Therefore, there is an urgent need to develop a new type of dual-bridge hybrid power assembly DHP (Dedicated Hybrid Powertrain) for commercial vehicles to meet the higher power performance requirements of commercial vehicles. Summary of the Invention

[0004] The purpose of the present invention is to provide a dual-bridge hybrid power system for commercial vehicles and a working method thereof, so as to solve the technical problems of large size and weight of the multi-gear box, power interruption and low efficiency in the prior art.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions: In the first aspect, the present invention provides a dedicated hybrid power system for dual-bridge commercial vehicles, including a clutch, a mid-bridge hybrid transmission assembly, a first differential, and a rear-bridge two-speed electric drive axle; The mid-bridge hybrid transmission assembly includes a generator sliding sleeve, a generator, a first motor, and a shifting system; The clutch is respectively connected to the generator sleeve and the drive assembly; a generator driven pulley is arranged on the output shaft of the drive assembly; the generator driven pulley meshes with the generator output pulley of the generator; the motor sleeve has two gears, which are respectively connected to the generator driven pulley and one end of the input shaft; a motor driven pulley is arranged on the input shaft; the motor driven pulley meshes with the motor output pulley of the first motor; the other end of the input shaft is connected to a first differential through a shifting system, and both sides of the first differential are respectively connected to a first wheel.

[0006] Further, the shifting system includes an input shaft driving pulley connected to the other end of the input shaft, a first intermediate shaft high gear, a first intermediate shaft low gear, a first low gear output pulley, a second intermediate shaft low gear, a second intermediate shaft high gear, and a first shifting sleeve; the input shaft driving pulley meshes with the first intermediate shaft high gear and the second intermediate shaft high gear respectively; the first shifting sleeve is connected to the input shaft of the first differential, and a first low gear output pulley is arranged on the input shaft of the first differential; the first low gear output pulley meshes with the first intermediate shaft low gear and the second intermediate shaft low gear respectively; the first intermediate shaft high gear and the first intermediate shaft low gear are fixedly connected; the second intermediate shaft low gear and the second intermediate shaft high gear are fixedly connected.

[0007] Further, the first shifting sleeve has three gears, which are respectively connected to the input shaft driving pulley, connected to the first low gear output pulley, and in neutral.

[0008] Further, the two-speed electric drive axle of the rear axle includes a second motor, a third intermediate shaft high gear, a third intermediate shaft low gear, a second low gear output pulley, a second shifting sleeve, and a high gear output pulley; the third intermediate shaft high gear and the third intermediate shaft low gear are fixedly connected to the output shaft of the second motor; the second low gear output pulley, the second shifting sleeve, and the high gear output pulley are connected to a second differential, and both sides of the second differential are connected to a second wheel; the third intermediate shaft high gear meshes with the high gear output pulley, and the third intermediate shaft low gear meshes with the second shifting sleeve; the second shifting sleeve is located between the second low gear output pulley and the high gear output pulley.

[0009] Further, the second shifting sleeve has three gears, which are respectively connected to the second low gear output pulley, connected to the high gear output pulley, and in neutral.

[0010] In a second aspect, the present invention provides a working method of the commercial vehicle double-bridge hybrid power system, including the following steps: When the vehicle is stationary, it enters the parking power generation state; at this time, the first shifting sleeve is in the neutral state; the generator sleeve meshes with the generator driven pulley, and the drive assembly drives the generator output pulley to rotate forward, and the generator outputs negative torque and negative power, which is the parking power generation state; When the vehicle is running, the medium-bridge hybrid transmission and the rear-axle two-speed electric drive axle are coordinated according to the vehicle speed for individual drive or combined drive. When the vehicle is running with insufficient power, the drive assembly starts to intervene and generates additional power through the generator. The medium-bridge hybrid transmission and the rear-axle two-speed electric drive axle select to perform individual drive or combined drive according to the required power. When the vehicle performs energy recovery, during the vehicle's coasting or braking process, the kinetic energy of the whole vehicle is recovered by the first motor and the second motor. The two motors are in the power generation state, with negative power, and the energy returns to the battery for subsequent use.

[0011] Further, when the vehicle is running, the steps of coordinating the medium-bridge hybrid transmission and the rear-axle two-speed electric drive axle for individual drive or combined drive according to the demand specifically include: When the vehicle starts and runs at medium and low speeds, the vehicle is in pure electric operation mode; when the required power is less than the first preset threshold, the rear-axle two-speed electric drive axle drives alone, and the medium-bridge hybrid transmission assembly is disengaged and does not participate in driving; when the required power is greater than the first preset threshold, the medium-bridge hybrid transmission and the rear-axle two-speed electric drive axle jointly participate in driving the whole vehicle. When the vehicle is running at medium speed, the medium-bridge hybrid transmission and the rear-axle two-speed electric drive axle perform gear shifting according to the vehicle speed, acceleration, and required power. The medium-bridge hybrid transmission and the rear-axle two-speed electric drive axle are coordinated to ensure that there is no interruption in the power during the vehicle's gear shifting. When the vehicle is running at high speed, the medium-bridge hybrid transmission switches to the direct gear, and the drive assembly participates in the work; the second shift sleeve of the rear-axle two-speed electric drive axle meshes with the high-speed output wheel or is directly disengaged.

[0012] Further, when the vehicle starts and runs at medium and low speeds, the vehicle is in pure electric operation mode; when the required power is less than the first preset threshold, the rear-axle two-speed electric drive axle drives alone, and the medium-bridge hybrid transmission assembly is disengaged and does not participate in driving; when the required power is greater than the first preset threshold, the steps of the medium-bridge hybrid transmission and the rear-axle two-speed electric drive axle jointly participating in driving the whole vehicle specifically include: When starting in low gear and the required power is less than the first preset threshold, the second shift sleeve meshes with the second low-speed output wheel, and the second motor drives alone; when the required power is greater than the first preset threshold, the medium-bridge hybrid transmission and the rear-axle two-speed electric drive axle jointly participate in driving the whole vehicle. The first shift sleeve meshes with the first low-speed output wheel, the second shift sleeve meshes with the second low-speed output wheel, and the first motor and the second motor drive together.

[0013] Further, when the vehicle is running at medium speed, the steps of the medium-bridge hybrid transmission and the rear-axle two-speed electric drive axle performing gear shifting according to the vehicle speed, acceleration, and required power, and the medium-bridge hybrid transmission and the rear-axle two-speed electric drive axle being coordinated to ensure that there is no interruption in the power during the vehicle's gear shifting specifically include: When the vehicle is running at medium speed, the first motor of the mid-bridge hybrid transmission transmits power through the first low-gear output wheel, and the second motor of the rear-bridge two-speed electric drive axle drives simultaneously through the second low-gear output wheel; when the vehicle enters a gear shift, the mid-bridge hybrid transmission maintains driving and increases the driving torque according to the torque distribution strategy. The second shift sleeve of the rear-bridge two-speed electric drive axle meshes with the high-gear output wheel, and then, through the torque distribution strategy, the output torques of the first motor and the second motor are adjusted to meet the driving requirements of the whole vehicle.

[0014] Further, when the vehicle is running at high speed, the mid-bridge hybrid transmission switches to the direct gear and the drive assembly participates in the work; the step that the second shift sleeve of the rear-bridge two-speed electric drive axle meshes with the high-gear output wheel specifically includes: When the vehicle is running at high speed and the drive assembly participates in the work, the generator sleeve of the mid-bridge hybrid transmission meshes with the gear on the input shaft, and the first shift sleeve meshes with the input shaft driving wheel to engage the direct gear; the second motor increases the driving torque when the mid-bridge hybrid transmission shifts gears, ensuring that there is no power interruption in the whole vehicle during the gear shift process.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention discloses a double-bridge hybrid power system for commercial vehicles and its working method, which combines a mid-bridge two-speed hybrid transmission with a rear-bridge two-speed electric drive axle to provide more powerful power support. When high power output is required, the engine and the motor can work together to meet the requirements of complex working conditions such as heavy load or acceleration. This hybrid power system adopts a highly integrated design, reducing the number and complexity of components, and having a small overall size and weight. The present invention adopts a double-bridge drive method, with stronger power; it has extended range operation at medium and low speeds and direct engine drive at high speeds, with better fuel economy; it has fewer gears, and the cooperation between the mid-rear axles realizes no power interruption, with better smoothness; the structure is simple, and compared with the PS planetary gear train architecture, it has higher reliability and broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required to be used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention, and thus should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can be obtained based on these drawings without creative efforts.

[0017] Figure 1 It is the transmission principle diagram of a double-bridge hybrid power system for commercial vehicles of the present invention; Figure 2 It is the transmission principle diagram of the vehicle for on-vehicle power generation in the embodiment of the present invention; Figure 3For the vehicle start-up and medium- and low-speed operation of the embodiment of the present invention, it is the transmission principle diagram of single drive of the rear axle; Figure 4 For the vehicle start-up and medium- and low-speed operation of the embodiment of the present invention, it is the transmission principle diagram of dual drive of the middle and rear axles; Figure 5 For the medium-speed operation of the vehicle of the embodiment of the present invention, it is the transmission principle diagram of the rear axle gearbox switching to a high gear; Figure 6 For the high-speed operation of the vehicle of the embodiment of the present invention, it is the transmission principle diagram; Figure 7 For the power-depleted operation of the vehicle of the embodiment of the present invention, it is the transmission principle diagram; Figure 8 For the energy recovery of the vehicle of the embodiment of the present invention, it is the transmission principle diagram.

[0018] Wherein: 1 - engine; 2 - clutch; 3 - generator driven wheel; 4 - generator sliding sleeve; 5 - motor output wheel; 6 - first motor; 7 - first intermediate shaft high gear; 8 - first intermediate shaft low gear; 9 - first low gear output wheel; 10 - second intermediate shaft low gear; 11 - first gear shifting sliding sleeve; 12 - second intermediate shaft high gear; 13 - input shaft driving wheel; 14 - generator; 15 - motor driven wheel; 16 - input shaft; 17 - generator output wheel; 18 - first differential; 19 - first wheel; 20 - second motor; 21 - third intermediate shaft high gear; 22 - third intermediate shaft low gear; 23 - second low gear output wheel; 24 - second gear shifting sliding sleeve; 25 - high gear output wheel; 26 - second differential; 27 - second wheel. Detailed implementation manners

[0019] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some but not all of the embodiments of the present invention. Usually, the components of the embodiments of the present invention described and shown in the accompanying drawings here can be arranged and designed in various different configurations.

[0020] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed present invention, but merely represents selected embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0021] It should be noted that: similar reference numerals and letters denote similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0022] In the description of the embodiments of the present invention, it should be noted that if terms such as "upper", "lower", "horizontal", "inner", etc. are used to indicate the orientation or positional relationship, it is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the invention product is usually placed during use. This is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention. In addition, terms such as "first" and "second" are only used for distinguishing descriptions and cannot be construed as indicating or implying relative importance.

[0023] In addition, if the term "horizontal" appears, it does not mean that the component is required to be absolutely horizontal, but it can be slightly inclined. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but it can be slightly inclined.

[0024] In the description of the embodiments of the present invention, it should also be noted that unless otherwise clearly specified and limited, if terms such as "set", "installed", "connected", "connected" are used, they should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0025] The following further describes the present invention in detail with reference to the drawings: See Figure 1 , an embodiment of the present invention discloses a dual-bridge hybrid power system for commercial vehicles, including a clutch 2, a mid-bridge hybrid transmission assembly, and a first differential 18; the mid-bridge hybrid transmission assembly includes a generator sliding sleeve 4, a generator 14, a first motor 6, and a shifting system; the clutch 2 is respectively connected to the generator sliding sleeve 4 and a driving component; a generator driven wheel 3 is arranged on the output shaft of the driving component; the generator driven wheel 3 meshes with the generator output wheel 17; the generator output wheel 17 is connected to the generator 14; the motor sliding sleeve 4 has two gears, which are respectively connected to the generator driven wheel 3 and one end of the input shaft 16; a motor driven wheel 15 is arranged on the input shaft 16; the motor driven wheel 15 meshes with the motor output wheel 5, and the motor output wheel 5 is connected to the first motor 6; the other end of the input shaft 16 is connected to one end of the first differential 18 through the shifting system, and both sides of the first differential 18 are respectively connected to the first wheels 19.

[0026] This system adopts a two-speed hybrid transmission in the middle bridge combined with a two-speed electric drive axle in the rear bridge, with dual-bridge drive, providing stronger power performance. Preferably, the drive component is the engine 1, which operates in range-extending mode at medium and low speeds and directly drives the engine at high speeds, offering better fuel economy. With fewer gears, the cooperation between the middle and rear axles ensures uninterrupted power, resulting in better ride comfort. The structure is simple and has higher reliability compared to the PS planetary gear architecture.

[0027] In a feasible embodiment of the present invention, the shift system includes an input shaft driving wheel 13 connected to the other end of the input shaft 16, a first intermediate shaft high-speed gear 7, a first intermediate shaft low-speed gear 8, a first low-speed output gear 9, a second intermediate shaft low-speed gear 10, a second intermediate shaft high-speed gear 12, and a first shift sleeve 11. The input shaft driving wheel 13 meshes with the first intermediate shaft high-speed gear 7 and the second intermediate shaft high-speed gear 12 respectively. The first shift sleeve 11 is connected to the input shaft of the first differential 18, and the first low-speed output gear 9 is arranged on the input shaft of the first differential 18. The first low-speed output gear 9 meshes with the first intermediate shaft low-speed gear 8 and the second intermediate shaft low-speed gear 10 respectively. The first intermediate shaft high-speed gear 7 and the first intermediate shaft low-speed gear 8 are fixedly connected. The second intermediate shaft low-speed gear 10 and the second intermediate shaft high-speed gear 12 are fixedly connected. In this embodiment, the first shift sleeve 11 has three gears, namely connected to the input shaft driving wheel 13, connected to the first low-speed output gear 9, and neutral.

[0028] In a feasible embodiment of the present invention, the two-speed electric drive axle in the rear bridge includes a second motor 20, a third intermediate shaft high-speed gear 21, a third intermediate shaft low-speed gear 22, a second low-speed output gear 23, a second shift sleeve 24, and a high-speed output gear 25. The output shaft of the second motor 20 is fixedly connected with the third intermediate shaft high-speed gear 21 and the third intermediate shaft low-speed gear 22. The second low-speed output gear 23, the second shift sleeve 24, and the high-speed output gear 25 are connected to the second differential 26, and the two sides of the second differential 26 are connected with second wheels 27. The third intermediate shaft high-speed gear 21 meshes with the high-speed output gear 25, and the third intermediate shaft low-speed gear 22 meshes with the second shift sleeve 24. The second shift sleeve 24 is located between the second low-speed output gear 23 and the high-speed output gear 25. Among them, the second shift sleeve 24 has three gears, namely connected to the second low-speed output gear 23, connected to the high-speed output gear 25, and neutral.

[0029] The embodiment of the present invention discloses a working method for a dual-bridge hybrid power system of a commercial vehicle, including the following steps: ① When the vehicle is stationary, it enters the parking power generation state. At this time, the first shift sleeve 11 is in the middle position, and the gear is in neutral. The generator sleeve 4 meshes with the generator driven wheel 3, and the drive component (engine 1) drives the generator output wheel 17 to rotate forward, and the generator 14 outputs negative torque and negative power, which is the parking power generation state, as Figure 2 shown; ② When the vehicle starts and runs at low and medium speeds, the vehicle is in pure electric operation mode. When the required power is low and less than the preset threshold, the two-speed electric drive axle at the rear axle drives alone, and the middle axle rotates along with it without participating in the drive. When starting in low gear, the second shifting sleeve 24 meshes with the second low-speed output wheel 23, and the second motor 20 drives alone. As Figure 3 shown, when the starting required power is large and greater than the preset threshold, the middle axle also intervenes and participates in the vehicle drive at the same time. At this time, the first shifting sleeve 11 meshes with the first low-speed output wheel 9, and the power of the first motor 6 is output through the low gear of the middle axle transmission. The rear axle works according to Figure 3 the method, and the middle and rear axles jointly participate in the drive. As Figure 4 shown; ③ Shifting process of the rear axle transmission during medium-speed operation of the vehicle. Each of the middle and rear axles of the vehicle is equipped with a two-speed gearbox. During the vehicle operation, the middle and rear axle transmissions determine the gear shifting strategy according to vehicle speed, acceleration, required power, etc. And during the shifting process, through the coordination of the middle and rear axles, it is ensured that there is no interruption in the vehicle shifting power. When the vehicle runs at medium speed, the first motor 6 of the middle axle hybrid transmission transmits power through the first low-speed output wheel 9, and the second motor 20 of the two-speed electric drive axle at the rear axle drives simultaneously through the second low-speed output wheel 23; when the vehicle enters the shifting process, the middle axle hybrid transmission maintains the drive and increases the drive torque according to the torque distribution strategy to meet the power loss caused by the rear axle shifting. The second shifting sleeve 24 of the two-speed electric drive axle at the rear axle meshes with the high-speed output wheel 25, and then through the torque distribution strategy, the output torques of the first motor 6 and the second motor 20 are adjusted to meet the drive requirements of the whole vehicle. As Figure 5 shown.

[0030] ④ The middle axle hybrid transmission of the vehicle switches to the direct gear at high speed. When the vehicle enters high-speed operation, the power and efficiency of the motor start to decline at this time. In order to meet the vehicle power performance requirements and considering the high power and efficiency of the engine at high speed, the middle axle transmission will switch to the direct gear. At this time, the engine 1 participates in the work, the generator sleeve 4 of the middle axle hybrid transmission meshes with the gear on the input shaft 16, and the first shifting sleeve 11 meshes with the input shaft driving wheel 13 to engage the direct gear; the shifting process is similar to process ③, and the second motor 20 increases the drive torque when the middle axle hybrid transmission shifts gears to ensure that there is no power interruption in the whole vehicle during the shifting process. As Figure 6 shown.

[0031] ⑤ Power generation during power shortage. When the battery power of the whole vehicle is low and the battery power cannot meet the motor running according to the required power, the engine 1 starts to intervene and generates additional power through the generator 14. At this time, the system operation situation is combined with Figure 7 , and the middle and rear axles select to drive alone or jointly according to the required power.

[0032] ⑥ Energy recovery. The whole vehicle has an energy recovery function. During vehicle coasting or braking, the kinetic energy of the whole vehicle can be recovered by the first motor 6 and the second motor 20 through the middle and rear axle gearboxes. At this time, the two motors operate in the power generation state, with negative power, and the energy returns to the battery for subsequent use, such as Figure 8 shown; The working principle of the present invention is as follows: The overall size and weight of the multi-speed gearbox are relatively large, there is power interruption during gear shifting, there is jerks in the coordination of the clutch and the engine, the engine efficiency is low, the high-efficiency area is small and the fuel consumption is high. To solve the above-mentioned problems of the traditional gearbox. The present invention proposes a new type of double-bridge hybrid powertrain DHP (Dedicated Hybrid Powertrain) for commercial vehicles. When the vehicle is stationary, it enters the parking power generation state; at this time, the first shift sleeve 11 is in the neutral state; the generator sleeve 4 meshes with the generator driven wheel 3, and the engine 1 drives the generator output wheel 17 to rotate forward, and the generator 14 outputs negative torque and negative power, which is the parking power generation state; when the vehicle is running, according to the vehicle speed, the middle-bridge hybrid gearbox and the rear-bridge two-speed electric drive axle are coordinated to drive separately or jointly; when the vehicle is running with insufficient power, the engine 1 starts to intervene and generates additional power through the generator 14, and the middle-bridge hybrid gearbox and the rear-bridge two-speed electric drive axle are selected to drive separately or jointly according to the required power; when the vehicle performs energy recovery, during vehicle coasting or braking, the kinetic energy of the whole vehicle is recovered by the first motor 6 and the second motor 20, and the two motors are in the power generation state, with negative power, and the energy returns to the battery for subsequent use. The present invention adopts a two-speed hybrid gearbox in the middle bridge combined with a two-speed electric drive axle in the rear bridge, with double-bridge drive, stronger power performance; extended-range operation at medium and low speeds, direct drive of the engine at high speeds, better fuel economy; fewer gears, no power interruption in the coordination of the middle and rear axles, better smoothness; simple structure, higher reliability compared to the PS planetary gear structure.

[0033] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A commercial vehicle dual-axle dedicated hybrid power system, characterized in that: It includes a clutch (2), a mid-bridge hybrid gearbox assembly, a first differential (18) and a rear axle two-speed electric drive axle; The mid-bridge hybrid gearbox assembly comprises a generator sleeve (4), a generator (14), a first electric motor (6) and a gear shifting system; The clutch (2) is connected to the generator sleeve (4) and the drive assembly respectively; a generator driven wheel (3) is arranged on the output shaft of the drive assembly; the generator driven wheel (3) is meshed with the generator output wheel (17) of the generator (14); the motor sleeve (4) has two gears, which are respectively connected to the generator driven wheel (3) and connected to one end of the input shaft (16); a motor driven wheel (15) is arranged on the input shaft (16); the motor driven wheel (15) is meshed with the motor output wheel (5) of the first motor (6); the other end of the input shaft (16) is connected to the first differential (18) through a gear shifting system, and the two sides of the first differential (18) are respectively connected to the first wheels (19).

2. A commercial vehicle dual-bridge hybrid power system according to claim 1, characterized in that: The gear shifting system comprises an input shaft driving wheel (13) connected to the other end of the input shaft (16), a first intermediate shaft high gear wheel (7), a first intermediate shaft low gear wheel (8), a first low gear output wheel (9), a second intermediate shaft low gear wheel (10), a second intermediate shaft high gear wheel (12) and a first gear-engaging sleeve (11); the input shaft driving wheel (13) is meshed with the first intermediate shaft high gear wheel (7) and the second intermediate shaft high gear wheel (12) respectively; the first gear-engaging sleeve (11) is connected to the input shaft of the first differential (18), and a first low gear output wheel (9) is arranged on the input shaft of the first differential (18); the first low gear output wheel (9) is meshed with the first intermediate shaft low gear wheel (8) and the second intermediate shaft low gear wheel (10) respectively; the first intermediate shaft high gear wheel (7) and the first intermediate shaft low gear wheel (8) are fixedly connected; and the second intermediate shaft low gear wheel (10) and the second intermediate shaft high gear wheel (12) are fixedly connected.

3. A commercial vehicle dual-bridge hybrid power system according to claim 2, characterized in that: The first gear-engaging sliding sleeve (11) has three gear positions, namely connected to the input shaft driving wheel (13), connected to the first low-gear output wheel (9), and neutral.

4. A commercial vehicle dual-bridge hybrid power system according to claim 1, characterized in that: The rear axle two-speed electric drive axle comprises a second electric motor (20), a third intermediate shaft high-speed wheel (21), a third intermediate shaft low-speed wheel (22), a second low-speed output wheel (23), a second gear-engaging sleeve (24) and a high-speed output wheel (25); the third intermediate shaft high-speed wheel (21) and the third intermediate shaft low-speed wheel (22) are fixedly connected to the output shaft of the second electric motor (20); the second low-speed output wheel (23), the second gear-engaging sleeve (24) and the high-speed output wheel (25) are connected to a second differential (26), and the two sides of the second differential (26) are connected to a second wheel (27); the third intermediate shaft high-speed wheel (21) and the high-speed output wheel (25) are meshed, and the third intermediate shaft low-speed wheel (22) and the second gear-engaging sleeve (24) are meshed; the second gear-engaging sleeve (24) is located between the second low-speed output wheel (23) and the high-speed output wheel (25).

5. A commercial vehicle dual-bridge hybrid power system according to claim 4, characterized in that: The second gear-engaging sliding sleeve (24) has three gear positions, namely connected to the second low-gear output wheel (23), connected to the high-gear output wheel (25), and neutral.

6. A method for operating a dual-bridge hybrid power system for a commercial vehicle according to any one of claims 1 to 5, characterized in that: The following steps are involved: When the vehicle is stationary, it enters a parking power generation state; at this time, the first gear sleeve (11) is in a neutral state; the generator sleeve (4) is meshed with the generator passive wheel (3), the drive component drives the generator output wheel (17) to rotate in the positive direction, and the generator (14) outputs negative torque and negative power, which is a parking power generation state; When the vehicle is running, the mid-axle hybrid gearbox and the two-speed electric drive axle of the rear axle are coordinated to drive individually or together according to the vehicle speed; When the vehicle runs out of power, the drive component starts to intervene, and the generator (14) is used to generate power for extended range, and the mid-bridge hybrid gearbox and the rear-bridge two-speed electric drive axle are driven individually or together according to the required power selection; When the vehicle is performing energy recovery, during the vehicle coasting or braking process, the kinetic energy of the entire vehicle is recovered by the first motor (6) and the second motor (20), the two motors are in a power generation state, the power is negative, and the energy is returned to the battery for subsequent use.

7. The operating method of a commercial vehicle dual-bridge hybrid power system according to claim 6, characterized in that: When the vehicle is running, the steps of coordinating the mid-bridge hybrid gearbox and the rear-bridge two-speed electric drive axle to drive individually or together according to demand specifically include: When the vehicle starts and runs at medium and low speeds, the vehicle is in pure electric operation mode; when the required power is less than the first preset threshold, the two-speed electric drive axle of the rear axle is driven alone, and the mid-axle hybrid gearbox assembly is removed and does not participate in the driving; when the required power is greater than the first preset threshold, the mid-axle hybrid gearbox and the two-speed electric drive axle of the rear axle jointly participate in the driving of the whole vehicle; When the vehicle is running at medium speed, the mid-axle hybrid transmission and the two-speed electric drive axle on the rear axle switch gears according to vehicle speed, acceleration and required power. The mid-axle hybrid transmission and the two-speed electric drive axle on the rear axle coordinate to ensure that the vehicle shifts without interruption; When the vehicle is running at high speed, the mid-bridge hybrid gearbox switches to direct gear, and the drive assembly participates in the operation; the second gear-engaging sliding sleeve (24) of the rear axle two-speed electric drive bridge is engaged with the high-speed output wheel (25) or is directly disengaged.

8. The operating method of a commercial vehicle dual-bridge hybrid power system according to claim 6, characterized in that: When the vehicle starts and runs at medium and low speeds, the vehicle is in a pure electric running mode; when the required power is less than a first preset threshold, the two-speed electric drive axle of the rear axle is driven alone, and the mid-axle hybrid gearbox assembly is disconnected and does not participate in the driving; When the required power is greater than the first preset threshold, the mid-bridge hybrid gearbox and the two-speed electric drive axle of the rear axle jointly participate in the vehicle driving steps, specifically including: When starting in low gear and the required power is less than a first preset threshold, the second gear-engaging sleeve (24) meshes with the second low-gear output wheel (23), and the second electric motor (20) drives alone; when the required power is greater than the first preset threshold, the mid-bridge hybrid gearbox and the two-gear electric drive axle of the rear axle jointly participate in driving the entire vehicle, the first gear-engaging sleeve (11) meshes with the first low-gear output wheel (9), the second gear-engaging sleeve (24) meshes with the second low-gear output wheel (23), and the first electric motor (6) and the second electric motor (20) drive together.

9. The operating method of a commercial vehicle dual-bridge hybrid power system according to claim 6, characterized in that: When the vehicle is running at medium speed, the mid-bridge hybrid gearbox and the rear axle two-speed electric drive axle switch gears according to the vehicle speed, acceleration and required power, and the mid-bridge hybrid gearbox and the rear axle two-speed electric drive axle coordinate to ensure that the whole vehicle shifts gears without interruption, specifically including: When the vehicle is running at medium speed, the first motor (6) of the mid-axle hybrid transmission transmits power through the first low-gear output wheel (9), and the second motor (20) of the rear axle two-gear electric drive bridge drives simultaneously through the second low-gear output wheel (23); when the vehicle enters a gear shift, the mid-axle hybrid transmission maintains driving and increases the driving torque according to the torque distribution strategy, the second gear-engaging sliding sleeve (24) of the rear axle two-gear electric drive bridge meshes with the high-gear output wheel (25), and then the output torque of the first motor (6) and the second motor (20) is adjusted according to the torque distribution strategy to meet the driving demand of the entire vehicle.

10. The operating method of a commercial vehicle dual-bridge hybrid power system according to claim 6, characterized in that: When the vehicle is running at high speed, the mid-bridge hybrid transmission switches to direct gear, and the drive assembly participates in the operation; The step of meshing the second gear-engaging sliding sleeve (24) of the rear axle two-speed electric drive axle with the high-speed output wheel (25) specifically comprises: When the vehicle is running at high speed, the drive assembly is engaged, the generator sleeve (4) of the mid-bridge hybrid gearbox is meshed with the gear of the input shaft (16), and the first gear-engaging sleeve (11) is meshed with the input shaft driving wheel (13) to engage in direct gear; the second electric motor (20) increases the driving torque when the mid-bridge hybrid gearbox is shifted, ensuring that there is no power interruption for the entire vehicle during the gear shifting process.

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