A hybrid power system applied to diesel heavy truck

Abstract

The application provides a hybrid power system applied to a diesel heavy truck, which comprises an engine, an input shaft, two motors, four transmission units, a first gear shifting unit, two clutch modules, an output shaft and a drive axle; the engine is connected to the first clutch module through the input shaft, and the first clutch module is connected to the input end of the first transmission unit; the first transmission unit is connected with the first motor, the second transmission unit is connected with the second motor, and the first gear shifting unit is arranged between the first transmission unit and the second transmission unit; the second transmission unit is coaxially connected with the third transmission unit through the second clutch module; the third transmission unit and the fourth transmission unit are coaxially connected; and the fourth transmission unit is connected with the drive axle through the output shaft. The application is used to solve the problem of low oil saving rate of the diesel hybrid heavy truck. The application can realize series hybrid, parallel hybrid, series-parallel hybrid and stepless speed regulation hybrid, and can ensure that the system efficiency of the hybrid power whole vehicle is optimal under different working conditions.

Description

Technical Field

[0001] This invention belongs to the field of diesel heavy-duty truck technology, and specifically relates to a hybrid power system applied to diesel heavy-duty trucks. Background Technology

[0002] With the implementation of dual-carbon policies, carbon reduction and emission reduction have become one of the most urgent tasks for the transportation industry. Heavy-duty commercial vehicles are major carbon emitters in the transportation sector, therefore, achieving carbon reduction and emission reduction in heavy-duty commercial vehicles is of great significance to the entire transportation industry's goal of carbon neutrality. Carbon reduction measures for heavy-duty commercial vehicles mainly include powertrain carbon reduction measures and whole-vehicle carbon reduction measures. The core of powertrain carbon reduction lies in improving system efficiency, with conventional measures relying primarily on improving engine thermal efficiency and transmission system efficiency. However, as engine thermal efficiency reaches over 50%, the return on investment for improving thermal efficiency gradually weakens. On the other hand, a zero-carbon or carbon-neutral fuel supply system has not yet been established, making it extremely difficult to reduce carbon emissions solely through engine reduction. Therefore, it is urgently necessary to address carbon reduction from the perspective of the entire powertrain.

[0003] Currently, hybrid systems have been proven to be one of the most effective ways to reduce carbon emissions in the passenger vehicle sector, especially series-parallel / continuously variable transmission (CVT) hybrid systems, which can simultaneously leverage the advantages of both series and parallel hybrid systems, significantly improving their adaptability to various operating conditions. However, the universal fuel consumption characteristics of diesel engines differ considerably from those of gasoline engines, and their operating characteristics also differ significantly. The three main contributions of hybrid systems to fuel saving include operating condition adjustment, reduction in transient fuel consumption, and regenerative braking. The benefits of operating condition adjustment in hybrid systems are lower than those of diesel engines. Summary of the Invention

[0004] To address the aforementioned technical problems, this invention proposes a hybrid power system for diesel heavy-duty trucks. It solves the problem of low fuel efficiency in diesel hybrid heavy-duty trucks and enables series hybrid, parallel hybrid, series-parallel hybrid, and continuously variable speed hybrid systems.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A hybrid power system for diesel heavy trucks includes an engine 1, an input shaft 3, two motors, four transmission units, a first shift unit 9, two clutch modules, an output shaft 28, and a drive axle 29.

[0007] The engine 1 is connected to the first clutch module 5 via the input shaft 3. The first clutch module 5 is connected to the input end of the first transmission unit. The first transmission unit is connected to the first motor 36, and the second transmission unit is connected to the second motor 37. A first shifting unit 9 is provided between the first transmission unit and the second transmission unit.

[0008] The second transmission unit is coaxially connected to the third transmission unit via the second clutch module 13; the third transmission unit and the fourth transmission unit are coaxially connected; the fourth transmission unit is connected to the drive axle 29 via the output shaft 28.

[0009] Furthermore, the system also includes a torsional damper 2;

[0010] After the engine 1 is connected to the torsional damper 2, it is connected to the first clutch module 5 through the input shaft 3.

[0011] Furthermore, the first transmission unit includes a first planetary carrier 30, a first sun gear 4, and a first gear ring 6;

[0012] The first clutch module 5 is connected to the first planetary carrier 30; the first sun gear 4 is connected to the output shaft; the first gear ring 6 is connected to the rotor 7 of the first motor; and the stator 8 of the first motor is connected to the gearbox housing 15.

[0013] Furthermore, the second transmission unit includes a second planetary carrier 14, a second ring gear 12, and a second sun gear 35;

[0014] The second sun gear 35 is connected to the first shift unit 9, the second gear ring 12 is connected to the second motor rotor 11, and the second motor stator 10 is connected to the gearbox housing 15.

[0015] Furthermore, the third transmission unit includes a third planetary carrier 21, a third sun gear 19, and a third gear ring 20;

[0016] The third sun gear 19 is coaxially connected to the gear 16. The gear 16 is connected to or disconnected from the third ring gear 20 by the second shift unit 17. The third planetary carrier 21 is connected to the output shaft. The third ring gear 20 is connected to or disconnected from the gearbox auxiliary housing 18 by the second shift unit 17.

[0017] Furthermore, the fourth transmission unit includes a fourth planetary carrier 26, a fourth sun gear 27, and a fourth gear ring 25;

[0018] The fourth sun gear 27 is coaxially connected to the gear 22. The gear 22 is connected to or disconnected from the fourth ring gear 25 by the third shift unit 23. The fourth planetary carrier 26 is connected to the output shaft. The fourth ring gear 25 is connected to or disconnected from the gearbox auxiliary housing 24 by the third shift unit 23.

[0019] Furthermore, the gear 22 is disposed between the third transmission unit and the fourth transmission unit.

[0020] Furthermore, the system's operating modes include a single-motor drive mode and a dual-motor drive mode within the pure electric operating mode;

[0021] In the single-motor drive mode: the first shift unit 9 is in neutral, the second clutch module 13 is closed, and the engine 1 is stopped;

[0022] In the dual-motor drive mode: the first shift unit 9 is connected to the second sun gear 35, and the engine 1 stops; the first motor drives the first sun gear 4 to rotate; the second clutch module 13 remains closed, and the second motor transmits torque to the third sun gear 19 to achieve drive.

[0023] Furthermore, the series mode of the system includes a first power generation mode and a second power generation mode; and the driving mode of both the first power generation mode and the second power generation mode is a single motor four-speed drive.

[0024] In the first power generation mode: the first clutch module 5 is disengaged; the first shift unit 9 is switched to the left and connected to the gearbox housing 15, realizing the self-locking of the first sun gear 4, the engine 1 starts, drives the first planetary carrier 30 to rotate, the first planetary carrier 30 drives the first gear ring 6 to rotate, drives the rotor 7 of the first motor to rotate, thereby realizing power generation;

[0025] In the second power generation mode: the first clutch module 5 is closed, the first shift unit 9 is in neutral, and the first transmission unit will self-lock. At this time, the engine speed and the motor speed are 1:1.

[0026] Furthermore, the parallel connection modes of the system include single-motor parallel connection mode and dual-motor parallel connection mode;

[0027] In the single-motor parallel mode: the first clutch module 5 is closed, the first shift unit 9 is shifted to the right, the second clutch module 13 is disengaged, and the first motor is a parallel drive motor;

[0028] Dual-motor parallel mode: the first clutch module 5 is closed, the first shift unit 9 is shifted to the right, and the second clutch module 13 is closed.

[0029] The effects described in the invention are merely those of the embodiments, and not all the effects of the invention. One of the above technical solutions has the following advantages or beneficial effects:

[0030] This invention proposes a hybrid power system for diesel heavy-duty trucks. The system includes an engine, an input shaft, two motors, four transmission units, a first shift unit, two clutch modules, an output shaft, and a drive axle. The engine is connected to the first clutch module via the input shaft, and the first clutch module is connected to the input end of the first transmission unit. The first transmission unit is connected to the first motor, and the second transmission unit is connected to the second motor. A first shift unit is located between the first and second transmission units. The second transmission unit is coaxially connected to the third transmission unit via the second clutch module. The third and fourth transmission units are coaxially connected. The fourth transmission unit is connected to the drive axle via the output shaft. This invention addresses the problem of low fuel efficiency in diesel hybrid heavy-duty trucks. This invention can achieve series hybrid, parallel hybrid, series-parallel hybrid, and continuously variable transmission (CVT) hybrid systems, ensuring optimal system efficiency for the hybrid vehicle under different operating conditions.

[0031] The first transmission unit of this invention adopts an integrated design with the motor rotor, which can significantly shorten the axial length of the motor arrangement. The second transmission unit of this invention has a clutch device between the planetary carrier and the sun gear. After the clutch is disengaged, the sun gear will not drive the motor rotor to rotate, reducing motor losses in parallel mode. The sun gear of the first transmission unit and the second transmission unit of this invention are equipped with a shifting mechanism, supporting neutral gear, thus decoupling the engine from the entire transmission system and achieving a series mode. Simultaneously, the shifting mechanism also enables the transmission of engine torque to the intermediate shaft.

[0032] The third transmission unit of this invention incorporates a shifting mechanism between the sun gears and the ring gear, enabling direct transmission with the entire planetary gear set locked, thus improving transmission efficiency. The third transmission unit of this invention also incorporates a locking structure between the ring gear and the gearbox housing, enabling the planetary mechanism to reduce speed and increase torque.

[0033] The fourth transmission unit of this invention incorporates a shifting mechanism between the sun gears and the ring gear, enabling direct transmission with the entire planetary gear set locked, thus improving transmission efficiency. The fourth transmission unit also features a locking structure between the ring gear and the gearbox housing, achieving speed reduction and torque increase in the planetary mechanism. Attached Figure Description

[0034] like Figure 1 This is Embodiment 1 of the present invention, which describes a hybrid power system applied to a diesel heavy-duty truck;

[0035] like Figure 2 This is a schematic diagram of the first modified structure of a hybrid power system applied to a diesel heavy truck according to Embodiment 1 of the present invention;

[0036] like Figure 3 This is a schematic diagram of a second modified structure in a hybrid power system applied to a diesel heavy truck according to Embodiment 1 of the present invention;

[0037] Legend: 1-Engine; 2-Torsion damper; 3-Input shaft; 4-First sun gear; 5-First clutch module; 6-First ring gear; 7-First motor rotor; 8-First motor stator; 9-First shift unit; 10-Second motor stator; 11-Second motor rotor; 12-Second ring gear; 13-Second clutch module; 14-Second planetary carrier; 15-Gearbox housing; 16-Gear; 17-Second shift unit; 18-First gearbox auxiliary housing; 19-Third gearbox housing 20-Sun gear; 21-Third ring gear; 22-Third planetary carrier; 23-Third shift unit; 24-Second gearbox auxiliary housing; 25-Fourth ring gear; 26-Fourth planetary carrier; 27-Fourth sun gear; 28-Output shaft; 29-Drive axle; 30-First planetary carrier; 31-First planetary mechanism; 32-Second planetary mechanism; 33-Third planetary mechanism; 34-Fourth planetary mechanism; 35-Second sun gear; 36-First motor; 37-Second motor. Detailed Implementation

[0038] To clearly illustrate the technical features of this solution, the invention will be described in detail below through specific embodiments and in conjunction with the accompanying drawings. The following disclosure provides many different embodiments or examples for implementing different structures of the invention. To simplify the disclosure of the invention, components and arrangements of specific examples are described below. Furthermore, reference numerals and / or letters may be repeated in different examples. This repetition is for simplification and clarity and does not in itself indicate a relationship between the various embodiments and / or arrangements discussed. It should be noted that the components illustrated in the drawings are not necessarily drawn to scale. Descriptions of well-known components, processing techniques, and processes are omitted in this invention to avoid unnecessarily limiting the invention.

[0039] Example 1

[0040] Embodiment 1 of the present invention proposes a hybrid power system for diesel heavy trucks to solve the problem of low fuel saving rate of diesel hybrid heavy trucks; the system includes: engine 1, input shaft 3, two motors, four transmission units, first shift unit 9, two clutch modules, output shaft 28 and drive axle 29;

[0041] Engine 1 is connected to first clutch module 5 via input shaft 3. First clutch module 5 is connected to the input end of first transmission unit. First transmission unit is connected to first motor, second transmission unit is connected to second motor, and first shift unit 9 is provided between first transmission unit and second transmission unit.

[0042] The second transmission unit is coaxially connected to the third transmission unit via the second clutch module 13; the third transmission unit and the fourth transmission unit are coaxially connected; the fourth transmission unit is connected to the drive axle 29 via the output shaft 28.

[0043] like Figure 1 This is Embodiment 1 of the present invention, a hybrid power system applied to a diesel heavy-duty truck; in Figure 1 The first transmission unit is a first planetary mechanism 31, the second transmission unit is a second planetary mechanism 32, the third transmission unit is a third planetary mechanism 33, and the fourth transmission unit is a fourth planetary mechanism 34.

[0044] The system also includes a torsional damper 2; after the engine 1 is connected to the torsional damper 2, it is connected to the first clutch module 5 via the input shaft 3.

[0045] Engine 1 is connected to the first planetary carrier 30 of the first planetary mechanism via torsional damper 2. The first sun gear 4 is connected to the output shaft. The first ring gear 6 is connected to the rotor 7 of the first motor. The stator 8 of the first motor is connected to the gearbox housing 15. A first clutch module 5 is provided between the torsional damper 2 and the second ring gear 6. This clutch device can be a clutch or a sliding sleeve shifting mechanism.

[0046] The first transmission unit includes a first planetary carrier 30, a first sun gear 4, and a first ring gear 6; the first clutch module 5 is connected to the first planetary carrier 30; the first sun gear 4 is connected to the output shaft, the first ring gear 6 is connected to the rotor 7 of the first motor, and the stator 8 of the first motor is connected to the gearbox housing 15.

[0047] The second transmission unit includes a second planetary carrier 14, a second ring gear 12, and a second sun gear 35; the second sun gear 35 is connected to the first shift unit 9, the second ring gear 12 is connected to the second motor rotor 11, and the second motor stator 10 is connected to the gearbox housing 15.

[0048] The first sun gear 4 of the first planetary mechanism coaxially drives the first shift unit 9. The left side of this shift mechanism is a self-locking connector with the gearbox ring gear, and the right side is the second sun gear 35 of the second planetary mechanism. This shift mechanism is a key component for realizing series-parallel operation.

[0049] The second sun gear 35 of the second planetary gear mechanism is connected to the first shifting unit 9, the second ring gear 12 is connected to the second motor rotor 11, and the second motor stator 10 is connected to the gearbox housing 15. A second clutch module 13 is provided between the second planetary carrier 14 and the gear 16. This clutch module enables the sun gear to disengage from the motor rotor when rotating, thereby reducing losses caused by motor idling.

[0050] The third transmission unit includes a third planetary carrier 21, a third sun gear 19, and a third ring gear 20. The third sun gear 19 is coaxially connected to a gear 16. The gear 16 is connected to or disconnected from the third ring gear 20 by a second shift unit 17. The third planetary carrier 21 is connected to the output shaft. The third ring gear 20 is connected to or disconnected from the gearbox auxiliary housing 18 by a second shift unit 17.

[0051] The fourth transmission unit includes a fourth planetary carrier 26, a fourth sun gear 27, and a fourth ring gear 25. The fourth sun gear 27 is coaxially connected to the gear 22. The gear 22 is connected to or disconnected from the fourth ring gear 25 by the third shift unit 23. The fourth planetary carrier 26 is connected to the output shaft. The fourth ring gear 25 is connected to or disconnected from the gearbox auxiliary housing 24 by the third shift unit 23.

[0052] The system's operating modes include single-motor drive mode and dual-motor drive mode in pure electric operating mode;

[0053] In single-motor drive mode: the first shift unit 9 is in neutral, the second clutch module 13 is closed, and the engine 1 is stopped; the second motor 37 acts as the drive motor, and the second clutch module 13 remains closed, transmitting torque to the third sun gear 19 to achieve drive. The second shift unit 17 is connected to the first gearbox auxiliary housing 18, and the third shift unit 23 is connected to the second gearbox auxiliary housing 24, for gear 1; the second shift unit 17 is connected to the first gearbox auxiliary housing 18, and the third shift unit 23 is connected to the sun gear coaxial gear 22, for gear 2; the second shift unit 17 is connected to the sun gear coaxial gear 16, and the third shift unit 23 is connected to the second gearbox auxiliary housing 24, for gear 3; the second shift unit 17 is connected to the sun gear coaxial gear 16, and the third shift unit 23 is connected to the sun gear coaxial gear 22, for gear 4. The gear changes in dual-motor drive mode are the same as in single-motor drive mode, and will not be described further below.

[0054] In dual-motor drive mode: the first shift unit 9 is connected to the second sun gear 35, and the engine 1; the first motor drives the first sun gear 4 to rotate; the second clutch module 13 remains closed, and the second motor transmits torque to the third sun gear 19 to achieve drive.

[0055] The system's series mode includes a first power generation mode and a second power generation mode; and both the first power generation mode and the second power generation mode are driven by a single motor in four gears; the first power generation mode is a high-speed power generation mode; and the second power generation mode is a low-speed power generation mode.

[0056] In the first power generation mode: the first clutch module 5 is disengaged; the first shift unit 9 is switched to the left and connected to the gearbox housing 15, realizing the self-locking of the first sun gear 4, the engine 1 starts, drives the first planetary carrier 30 to rotate, the first planetary carrier 30 drives the first gear ring 6 to rotate, drives the rotor 7 of the first motor to rotate, thereby realizing power generation; therefore, it is a high-speed power generation mode.

[0057] In the second power generation mode: the first clutch module 5 is closed, the first shift unit 9 is in neutral, and the first planetary mechanism 31 will self-lock. At this time, the engine speed and the motor speed are 1:1, so it is a low-speed power generation mode.

[0058] All drive modes are single drive with the second motor 37, and there are four gears, the same as the four gears in pure electric vehicles.

[0059] The parallel operation modes of the system include single-motor parallel operation mode and dual-motor parallel operation mode;

[0060] In single-motor parallel mode: the first clutch module 5 is closed, the first shift unit 9 is moved to the right, the second clutch module 13 is disengaged, and the first motor... 36 Parallel drive motors;

[0061] Dual-motor parallel mode: the first clutch module 5 is closed, the first shift unit 9 is shifted to the right, and the second clutch module 13 is closed.

[0062] The engine direct drive mode of the present invention is similar to the parallel single motor mode. The first clutch module 5 is closed, the first shift unit 9 is shifted to the right, the second clutch module 13 is disengaged, and the first motor 36 remains in motion but does not apply torque, resulting in some no-load loss.

[0063] The continuously variable speed regulation mode of this invention is more suitable for high-speed, low-torque operating conditions. When the first clutch module 5 is disengaged, the first shift unit 9 is moved to the right, the second clutch module 13 is disengaged, and the first motor 36 adjusts the engine speed and generates electricity.

[0064] Based on the hybrid power system for diesel heavy trucks proposed in Embodiment 1 of this invention, a modified structure for the hybrid power system for diesel heavy trucks is also provided.

[0065] like Figure 2 This is a schematic diagram of the first modified structure of a hybrid power system applied to a diesel heavy truck according to Embodiment 1 of the present invention; Figure 2 exist Figure 1 Based on this, the torsional damper 2 between engine 1 and the first gear ring 6 was removed.

[0066] like Figure 3 This is a schematic diagram of a second modified structure in a hybrid power system applied to a diesel heavy truck according to Embodiment 1 of the present invention; Figure 3 and Figure 1 In comparison, engine 1 is connected to the first sun gear 4 of the first planetary mechanism, and the fourth planetary carrier 26 is connected to the drive axle 29.

[0067] Embodiment 1 of this invention proposes a hybrid power system for diesel heavy-duty trucks, which addresses the problem of low fuel efficiency in diesel-hybrid heavy-duty trucks. This invention can achieve series hybrid, parallel hybrid, series-parallel hybrid, and continuously variable speed hybrid systems; it can ensure optimal system efficiency for the hybrid vehicle under different operating conditions.

[0068] In Embodiment 1 of this invention, the first planetary gear ring and the motor rotor of a hybrid power system applied to a diesel heavy-duty truck are integrated into a single design, which significantly shortens the axial length of the motor arrangement. A clutch device is installed between the planet carrier and the sun gear of the second planetary gear; when the clutch is disengaged, the sun gear will not drive the motor rotor to rotate, reducing motor losses in parallel operation. A shifting mechanism is provided between the sun gear of the first planetary gear and the second planetary gear, supporting neutral gear and decoupling the engine from the entire transmission system, achieving a series mode. Simultaneously, the shifting mechanism also enables the transmission of engine torque to the intermediate shaft.

[0069] The third planetary gear mechanism in the hybrid power system of a diesel heavy-duty truck proposed in Embodiment 1 of this invention features a shifting mechanism between the sun gear and the ring gear, enabling direct transmission with the entire planetary gear set locked, thus improving transmission efficiency. The third planetary gear mechanism of this invention also incorporates a locking structure between the ring gear and the gearbox housing, achieving the effect of speed reduction and torque increase.

[0070] The fourth planetary gear mechanism in a hybrid power system for diesel heavy-duty trucks, as proposed in Embodiment 1 of this invention, incorporates a shifting mechanism between the sun gear and the ring gear, enabling direct transmission with the entire planetary gear set locked, thus improving transmission efficiency. Furthermore, the fourth planetary gear mechanism of this invention features a locking structure between the ring gear and the gearbox housing, achieving the effect of speed reduction and torque increase.

[0071] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that the elements inherent in a process, method, article, or apparatus that includes a list of elements are included. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. Additionally, portions of the technical solutions provided in the embodiments of this application that are consistent with the implementation principles of corresponding technical solutions in the prior art have not been described in detail to avoid excessive elaboration.

[0072] While specific embodiments of the present invention have been described above in conjunction with the accompanying drawings, this is not intended to limit the scope of protection of the present invention. Those skilled in the art can make other modifications or variations based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Various modifications or variations that can be made by those skilled in the art without creative effort based on the technical solutions of the present invention are still within the scope of protection of the present invention.

Claims

1. A hybrid power system for use in diesel heavy-duty trucks, characterized in that, It includes an engine (1), an input shaft (3), two motors, four transmission units, a first shift unit (9), two clutch modules, an output shaft (28), and a drive axle (29). The engine (1) is connected to the first clutch module (5) via the input shaft (3), and the first clutch module (5) is connected to the input end of the first transmission unit; the first transmission unit is connected to the first motor (36), the second transmission unit is connected to the second motor (37), and a first shifting unit (9) is provided between the first transmission unit and the second transmission unit. The second transmission unit is coaxially connected to the third transmission unit via the second clutch module (13); the third transmission unit and the fourth transmission unit are coaxially connected; the fourth transmission unit is connected to the drive axle (29) via the output shaft (28). The first transmission unit includes a first planet carrier (30), a first sun gear (4), and a first gear ring (6); The first clutch module (5) is connected to the first planetary carrier (30); the first sun gear (4) is connected to the output shaft of the first transmission unit; the first gear ring (6) is connected to the rotor (7) of the first motor; and the stator (8) of the first motor is connected to the gearbox housing (15).

2. The hybrid power system for diesel heavy-duty trucks according to claim 1, characterized in that, The system also includes a torsional damper (2); After the engine (1) is connected to the torsional damper (2), it is connected to the first clutch module (5) via the input shaft (3).

3. A hybrid power system for diesel heavy-duty trucks according to claim 1, characterized in that, The second transmission unit includes a second planetary carrier (14), a second gear ring (12), and a second sun gear (35); The second sun gear (35) is connected to the first shift unit (9), the second gear ring (12) is connected to the second motor rotor (11), and the second motor stator (10) is connected to the gearbox housing (15).

4. A hybrid power system for diesel heavy-duty trucks according to claim 1, characterized in that, The third transmission unit includes a third planet carrier (21), a third sun gear (19), and a third gear ring (20). The third sun gear (19) is coaxially connected to the gear (16). The gear (16) is connected to or disconnected from the third gear ring (20) through the second shift unit (17). The third planet carrier (21) is connected to the output shaft of the third transmission unit. The third gear ring (20) is connected to or disconnected from the first gearbox auxiliary housing (18) through the second shift unit (17).

5. A hybrid power system for diesel heavy-duty trucks according to claim 1, characterized in that, The fourth transmission unit includes a fourth planetary carrier (26), a fourth sun gear (27), and a fourth gear ring (25). The fourth sun gear (27) is coaxially connected to the gear (22), and the gear (22) is connected or disconnected from the fourth ring gear (25) through the third shift unit (23). The fourth planetary carrier (26) is connected to the output shaft, and the fourth ring gear (25) is connected or disconnected from the second gearbox auxiliary housing (24) through the third shift unit (23).

6. A hybrid power system for diesel heavy-duty trucks according to claim 5, characterized in that, The gear (22) is positioned between the third transmission unit and the fourth transmission unit.

7. A hybrid power system for diesel heavy-duty trucks according to claim 1, characterized in that, The system's operating modes include a single-motor drive mode and a dual-motor drive mode within the pure electric operating mode. In the single-motor drive mode: the first shift unit (9) is in neutral, the second clutch module (13) is closed, and the engine (1) is stopped; In the dual-motor drive mode: the first shift unit (9) is connected to the second sun gear (35), the engine (1) stops; the first motor drives the first sun gear (4) to rotate; the second clutch module (13) remains closed, and the second motor transmits torque to the third sun gear (19) to achieve drive.

8. A hybrid power system for diesel heavy-duty trucks according to claim 1, characterized in that, The system's series mode includes a first power generation mode and a second power generation mode; and both the first power generation mode and the second power generation mode are driven by a single motor in four gears. In the first power generation mode: the first clutch module (5) is disconnected; the first shift unit (9) is switched to the left and connected to the gearbox housing (15), realizing the self-locking of the first sun gear (4), the engine (1) is started, driving the first planetary carrier (30) to rotate, the first planetary carrier (30) drives the first gear ring (6) to rotate, driving the rotor (7) of the first motor to rotate, thereby realizing power generation; In the second power generation mode: the first clutch module (5) is closed, the first shift unit (9) is in neutral, the first transmission unit will self-lock, and at this time the engine speed and the motor speed are 1:

1.

9. A hybrid power system for diesel heavy-duty trucks according to claim 1, characterized in that, The parallel operation modes of the system include single-motor parallel operation mode and dual-motor parallel operation mode; In the single-motor parallel mode: the first clutch module (5) is closed, the first shift unit (9) is shifted to the right, the second clutch module (13) is disengaged, and the first motor is a parallel drive motor; Dual-motor parallel mode: the first clutch module (5) is closed, the first shift unit (9) is shifted to the right, and the second clutch module (13) is closed.

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