Driving system for hybrid power tractor

Abstract

The invention relates to a driving system for a hybrid tractor, which comprises an engine, a generator, a front motor and a rear motor, and the engine is in transmission connection with a PTO (Power Take Off); the front axle input shaft is in transmission connection with the front motor and the normally-combined clutch input shaft, a normally-combined clutch is arranged on the normally-combined clutch input shaft, a parking brake is arranged on the normally-combined clutch input shaft, and the parking brake is connected with the rear axle. An input shaft of the normally-combined clutch is in transmission connection with a small cone shaft, a mode switching clutch is arranged on the small cone shaft, the small cone shaft is in transmission connection with the input shaft of the normally-combined clutch and a rear motor, and one end of a sun wheel shaft is connected with a rear wheel through a planetary gear mechanism. And a service brake is arranged on the sun wheel shaft. The normally-combined clutch input shaft, the normally-combined clutch and the transmission mechanism are arranged between the front axle and the rear axle, so that the four-wheel braking function is achieved.

Description

Technical Field

[0001] This invention relates to the field of hybrid tractor technology, and in particular to a drive system for a hybrid tractor. Background Technology

[0002] In the field of agricultural machinery, hybrid tractors are favored for their good fuel economy, simple transmission system structure, and continuously variable transmission.

[0003] Most tractors use a fixed mechanical transmission ratio in the transfer case within the transmission system, which generally results in a certain lead ratio for the front wheels. As a result, during four-wheel drive operation, the theoretical speed of the front wheels is always greater than that of the rear wheels, and the slip ratios of the front and rear drive wheels are always unequal. Consequently, under the same soil conditions, the adhesion of the front and rear drive wheels cannot be fully utilized simultaneously. Due to the lead ratio of the front wheels, there is additional slippage of the front wheels, which in turn causes additional slippage power loss and reduces the overall traction efficiency of the machine.

[0004] For steering considerations, since the front wheels travel a longer distance than the rear wheels when turning, and the lead ratio of the front wheels decreases as the front wheel deflection angle increases, the front wheels need to have a certain lead ratio. As a result, it is impossible to achieve optimal traction efficiency during four-wheel drive traction operations.

[0005] In actual use, the dynamic radius of the front and rear tires of a tractor will change due to tire size errors, wear, dynamic changes in load, and tire pressure. This makes it difficult for the theoretical speeds of the front and rear drive wheels to be equal. To solve the problem of the inability to dynamically adjust the speed of most existing tractors, there are publicly available technologies that use two electric motors to independently drive the front and rear axles in a series hybrid electric drive configuration. However, the existing configuration has the problem of insufficient braking capacity, and its braking performance is difficult to meet the certification requirements of exporting to countries such as the European Union. Summary of the Invention

[0006] In view of this, the object of the present invention is to provide a drive system for a hybrid tractor.

[0007] The technical solution adopted by the present invention to solve the above-mentioned technical problems is: a hybrid power tractor drive system, including an engine, a generator, a front electric motor and a rear electric motor, wherein the engine is connected to the generator through a universal joint drive shaft, the generator is connected to the PTO input shaft through a first gear transmission mechanism, and the PTO input shaft is connected to the PTO transmission through a PTO clutch and a second gear transmission mechanism arranged in sequence. It also includes a small cone shaft, a sun gear shaft, a normally engaged clutch input shaft, a rear axle, a front axle, and a front axle input shaft connected to the front axle. The front axle input shaft is equipped with an eleventh gear. The front motor is connected to the eleventh gear through a first transmission unit. The normally engaged clutch input shaft is equipped with a normally engaged clutch and a tenth gear that meshes with the eleventh gear. The normally engaged clutch input shaft is also connected in sequence to a parking brake, a normally engaged clutch intermediate shaft, a first spline sleeve, and a normally engaged clutch output shaft. The small cone shaft is equipped with the eighth gear and the mode switching clutch. The rear motor is connected to the eighth gear through the second transmission unit. The output shaft of the normally engaged clutch is connected to the small cone shaft through the third gear transmission mechanism. One end of the sun gear shaft is connected to the rear wheel via a planetary gear mechanism, and the other end is connected to the differential. The small cone shaft is connected to the differential via a third transmission unit. A service brake is installed on the sun gear shaft.

[0008] As a preferred embodiment, a torsional damper is also included, with one end connected to the engine output and the other end connected to a universal drive shaft.

[0009] As a preferred embodiment, the first gear transmission mechanism includes an idler shaft, a pump drive shaft, an input shaft connected to a generator, and a first gear disposed on the input shaft. The pump drive shaft is connected to a hydraulic pump, and a third gear is disposed on the pump drive shaft. A second gear that meshes with the first gear and the third gear is disposed on the idler shaft, and a thirteenth gear that meshes with the first gear and the second gear is disposed on the PTO input shaft.

[0010] As a preferred embodiment, the second gear transmission mechanism includes a fourth gear and a fifth gear connected to the PTO clutch, and also includes a sixth gear and a seventh gear connected to the PTO. The fourth gear meshes with the seventh gear, the fifth gear meshes with the sixth gear, and the PTO clutch is located between the thirteenth gear and the fourth gear.

[0011] As a preferred embodiment, the first transmission unit includes a front drive input shaft and a fifteenth gear disposed on the front drive input shaft and meshing with the eleventh gear, and the output end of the front motor is connected to the front drive input shaft through a second spline sleeve.

[0012] As a preferred embodiment, the parking brake is located between the normally engaged clutch and the first spline sleeve.

[0013] As a preferred embodiment, the second transmission unit includes a rear drive input shaft and a fourteenth gear disposed on the rear drive input shaft and meshing with the eighth gear, and the output end of the rear motor is connected to the rear drive input shaft through a third spline sleeve.

[0014] As a preferred embodiment, the third gear transmission mechanism includes a ninth gear disposed on the output shaft of the normally engaged clutch and a twelfth gear disposed on the small conical shaft and meshing with the ninth gear.

[0015] As a preferred embodiment, the planetary gear mechanism includes a planet carrier, a double planetary gear set, and a gear ring. The double planetary gear set includes a double planetary large gear and a double planetary small gear set coaxially and fixedly connected. The double planetary small gear sets mesh with the gear ring, and the double planetary large gear sets mesh with the sun gear set on the sun gear shaft. The double planetary large gear and the double planetary small gear set are connected to the rear gear set through the planet carrier.

[0016] As a preferred embodiment, the third transmission unit includes a small bevel gear mounted on a small bevel shaft, which meshes with a large bevel gear, and the large bevel gear is connected to the sun gear shaft via a differential.

[0017] The beneficial effects of this application are as follows: 1. This application achieves an increase in overall machine power by adopting a series hybrid electric drive route that uses two electric motors to independently drive the front and rear axles. The front and rear axles can be decoupled, allowing each axle to independently achieve dynamic adjustment of output speed and torque through electric motor drive. During four-wheel drive operation, the theoretical speeds of the front and rear wheels are equal, ensuring that the adhesion of both the front and rear wheels is fully utilized simultaneously, resulting in optimal traction efficiency. During steering, the front wheels have a certain lead ratio, maintaining driving force at all times, reducing the tendency for front wheel sideslip, and facilitating steering.

[0018] 2. This application achieves inter-axle connection and decoupling by setting up a normally engaged clutch shaft system and a normally engaged clutch and a third gear transmission mechanism between the front and rear axles. During braking, the normally engaged clutch engages, connecting the front and rear axles to achieve four-wheel braking function, solving the problem of insufficient braking capacity in existing series hybrid electric drive configurations where the front and rear axles can output independently; during four-wheel drive and two-wheel drive operations, the normally engaged clutch disengages, decoupling the front and rear axles to meet the needs of independent output from the front and rear axles.

[0019] 3. A parking brake is installed behind the normally engaged clutch between the front and rear axles. When the tractor is stopped and the engine is turned off, the normally engaged clutch engages, the front and rear axles are connected, and the parking brake is operated. The front and rear wheels provide static friction at the same time, which improves the longitudinal stability of the tractor.

[0020] 4. This application adopts a direct connection between the engine and the generator, and drives the PTO and hydraulic pump through the first gear transmission mechanism. At the same time, the generator can supply power to the front and rear electric motors or charge the battery, so that the engine can continuously operate in the efficient and economical range, reducing fuel consumption and emissions.

[0021] 5. This application allows the system to flexibly switch between various drive modes (such as pure electric front drive, pure electric rear drive, hybrid four-wheel drive, and engine direct drive PTO) by setting the mode switching clutch and the constantly engaged clutch, adapting to different working conditions and power requirements, and improving the applicability and maneuverability of the whole machine.

[0022] 6. The combination of the planetary gear mechanism and the differential in this application, as well as the third transmission unit composed of the small bevel gear and the large bevel gear, realizes the rational distribution of power to the rear axle and the differential function, further improving the vehicle's passability and handling stability under complex road conditions. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the transmission mechanism of the present invention.

[0024] Figure 2 This is a spatial distribution diagram of each axis of the present invention viewed from front to back.

[0025] Diagram markings: 1. Engine, 2. Torsional damper, 3. Universal joint drive shaft, 4. Generator, 5. First gear, 6. Second gear, 7. Third gear, 8. Hydraulic pump, 9. Sun gear shaft, 10. Double planetary pinion, 11. Planet carrier, 12. Ring gear, 13. Double planetary gear, 14. PTO Clutch, 15. Fourth gear, 16. Fifth gear, 17. Sixth gear, 18. Seventh gear, 19. Large bevel gear, 20. Service brake, 21. Small bevel gear, 22. Mode switching clutch, 23. Eighth gear, 24. Ninth gear, 25. First spline sleeve, 26. Parking brake, 27. Normally engaged clutch, 28. Tenth gear, 29. Eleventh gear, 30. Twelfth gear, 31. Thirteenth gear, 32. Fourteenth gear, 33. Rear motor, 34. Front motor, 35. Fifteenth gear, S1. Input shaft, S2. Idler shaft, S3. Pump drive shaft, S4. PTO input shaft, S5. Rear drive input shaft, S6. Small bevel shaft, S7. Front drive input shaft, S8. Front axle input shaft, S9. Normally engaged clutch input shaft, S9a. Normally engaged clutch intermediate shaft, S9b. Normally engaged clutch output shaft. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that, in the description of this invention, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," "outer," "front end," "rear end," "head," "tail," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, the terms "first," "second," "third," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0027] Please see Figure 1-2 This invention provides a hybrid power tractor drive system, including an engine 1, a generator 4, a front electric motor 34, and a rear electric motor 33. The engine 1 is connected to the generator 4 via a universal joint drive shaft 3. The generator 4 is connected to a PTO input shaft S4 via a first gear transmission mechanism. The PTO input shaft S4 is connected to the PTO drive via a PTO clutch 14 and a second gear transmission mechanism arranged sequentially. The system also includes a small cone shaft S6, a sun gear shaft 9, a normally engaged clutch input shaft S9, a rear axle, a front axle, and a front axle input shaft S8 connected to the front axle. An eleventh gear 29 is provided on the front axle input shaft S8. The front electric motor 34 is connected to the eleventh gear 29 via a first transmission unit. The normally engaged clutch input shaft S9... The vehicle is equipped with a normally engaged clutch 27 and a tenth gear 28 that meshes with the eleventh gear 29. The normally engaged clutch input shaft S9 is also connected in sequence to a parking brake 26, a normally engaged clutch intermediate shaft S9a, a first spline sleeve 25, and a normally engaged clutch output shaft S9b. The small cone shaft S6 is equipped with an eighth gear 23 and a mode switching clutch 22. The rear motor 33 is connected to the eighth gear 23 via a second transmission unit. The normally engaged clutch output shaft S9b is connected to the small cone shaft S6 via a third gear transmission mechanism. One end of the sun gear shaft 9 is connected to the rear wheel via a planetary gear mechanism, and the other end is connected to the differential. The small cone shaft S6 is connected to the differential via a third transmission unit. The sun gear shaft 9 is equipped with a service brake 20.

[0028] This also includes a torsional damper 2, one end of which is connected to the output end of the engine 1, and the other end is connected to the universal joint drive shaft 3. The universal joint drive shaft 3 is connected to the central shaft of the generator 4.

[0029] Specifically, the first gear transmission mechanism includes an idler shaft S2, a pump drive shaft S3, an input shaft S1 connected to the generator 4, and a first gear 5 mounted on the input shaft S1. One end of the input shaft S1 is connected to the central shaft of the generator 4, and the other end is connected to the first gear 5. The pump drive shaft S3 is connected to the hydraulic pump 8, and a third gear 7 is mounted on the pump drive shaft S3. The idler shaft S2 is equipped with a second gear 6 that meshes with the first gear 5 and the third gear 7. The PTO input shaft S4 is equipped with a thirteenth gear 31 that meshes with the first gear 5 and the second gear 6.

[0030] Combination Figure 1 As shown, the second gear transmission mechanism includes a fourth gear 15 and a fifth gear 16 connected to the PTO clutch 14, and a sixth gear 17 and a seventh gear 18 connected to the PTO. In this application, PTO refers to the PTO shaft head, which is connected to the machine tool. The fourth gear 15 meshes with the seventh gear 18, and the fifth gear 16 meshes with the sixth gear 17. The PTO clutch 14 is located between the thirteenth gear 31 and the fourth gear 15. The PTO clutch 14 controls the engagement or disengagement of the fourth gear 15 and the fifth gear 16 from the PTO input shaft S4 to control the transmission or interruption of power between them. It should be noted that any parts not detailed in this application are prior art.

[0031] Specifically, the generator 4 is electrically connected to the rear motor 33 and the front motor 34. The first transmission unit includes a front drive input shaft S7 and a fifteenth gear 35 that meshes with the eleventh gear 29 on the front drive input shaft S7. The output end of the front motor 34 is connected to the front drive input shaft S7 via a second spline sleeve. The parking brake 26 is located between the normally engaged clutch 27 and the first spline sleeve 25. The second transmission unit includes a rear drive input shaft S5 and a fourteenth gear 32 that meshes with the eighth gear 23 on the rear drive input shaft S5. The eighth gear 23 is connected to the small cone shaft S6 via a mode switching clutch 22. The output end of the rear motor 33 is connected to the rear drive input shaft S5 via a third spline sleeve. The third gear transmission mechanism includes a ninth gear 24 that meshes with the ninth gear 24 on the normally engaged clutch output shaft S9b and a twelfth gear 30 that meshes with the ninth gear 24 on the small cone shaft S6. Furthermore, the parking brake 26 is located after the normally engaged clutch 27. The normally engaged clutch input shaft S9 is connected to the normally engaged clutch intermediate shaft S9a through the parking brake 26. The normally engaged clutch intermediate shaft S9a is connected to the normally engaged clutch output shaft S9b through the first spline sleeve 25.

[0032] The planetary gear mechanism includes a planet carrier 11, a double planetary gear set, and a ring gear 12. The double planetary gear set includes a double planetary large gear 13 and a double planetary small gear 10 coaxially and fixedly connected. The double planetary small gear 10 meshes with the ring gear 12, and the double planetary large gear 13 meshes with the sun gear on the sun gear shaft 9. The ring gear 12 is fixed. The double planetary large gear 13 and the double planetary small gear 10 are connected to the rear wheel via the planet carrier 11. The double planetary gear set is mounted on the planet carrier 11 via a planet gear shaft, and the planet carrier 11 is connected to the rear wheel. The third transmission unit includes a small bevel gear 21 mounted on a small bevel shaft S6. The small bevel gear 21 meshes with a large bevel gear 19, and the large bevel gear 19 is connected to the sun gear shaft 9 via a differential.

[0033] Combination Figure 2 As shown, Figure 2 As shown, input shaft S1, PTO input shaft S4, small cone shaft S6, and front axle input shaft S8 are located on the longitudinal center plane of the tractor. Rear drive input shaft S5 and front drive input shaft S7 are located on the lower left side of the drive system, which facilitates the overall coordinated arrangement of the left and right sides of the machine. Idler shaft S2 and pump drive shaft S3 are located on the upper left side of the drive system, which facilitates the installation and arrangement of hydraulic pump 8. The commonly used clutch input shaft S9 is located on the right side of the drive system, which reduces the space occupied on the right side of the machine and facilitates the arrangement of components on the right side of the machine. The spatial arrangement of each shaft of the drive system is well coordinated with the whole machine and meets the needs of the installation and arrangement of the rest of the machine. The input shaft S1, idler shaft S2, and pump drive shaft S3 form the driving hydraulic pump shaft system; the input shaft S1, idler shaft S2, and PTO input shaft S4 form the driving PTO power output shaft system; the rear drive input shaft S5 and small cone shaft S6 form the driving rear wheel shaft system; the front drive input shaft S7 and front axle input shaft S8 form the driving front wheel shaft system; and the front axle input shaft S8, normally engaged clutch input shaft S9, and small cone shaft S6 form the four-wheel braking shaft system.

[0034] When engine 1 drives the hydraulic pump, after engine 1 starts running, the engine power is transmitted to the pump drive shaft S3 through torsional damper 2, universal drive shaft 3, generator 4 central shaft, input shaft S1, first gear 5, second gear 6, and third gear 7. The pump drive shaft S3 is used to drive the hydraulic pump 8, so that mechanical power is converted into hydraulic power output.

[0035] When engine 1 drives PTO to achieve power output, after engine 1 starts, the power of engine 1 is transmitted to PTO clutch 14 through torsional damper 2, universal drive shaft 3, generator 4 central shaft, input shaft S1, first gear 5, second gear 6, thirteenth gear 31, and PTO input shaft S4. At this time, PTO clutch 14 is engaged, and power is transmitted to fourth gear 15 and fifth gear 16. When the PTO shift sleeve is operated to shift to the left or right, the power is transmitted to seventh gear 18 or sixth gear 17 respectively, and then to PTO shaft head to drive the rotary tillage operation of the implement.

[0036] When the tractor is engaged in traction operations, the engine 1 drives the central shaft of the generator 4 to rotate via the torsional damper 2 and the universal joint drive shaft 3. The mechanical power of the engine is converted into the electrical power of the generator 4. The engine 4 is electrically connected to the rear motor 33 and the front motor 34, converting electrical power into mechanical power. The rear motor 33 outputs the corresponding power according to the needs of the rear wheels, and the front motor 34 outputs the corresponding power according to the needs of the front wheels.

[0037] When the tractor is in four-wheel drive operation, the power from the rear motor 33 is transmitted to the mode switching clutch 22 via the third spline sleeve, rear drive input shaft S5, fourteenth gear 32, and eighth gear 23. At this time, the mode switching clutch 22 is engaged, and the power from the rear motor 33 is transmitted to the rear wheels via the small bevel shaft S6, small bevel gear 21, large bevel gear 19, sun gear shaft 9, double planetary large gear 13, double planetary small gear 10, and planet carrier 11, providing traction to the rear wheels. The power from the front motor 34 is transmitted to the front wheels via the second spline sleeve, front drive input shaft S7, fifteenth gear 35, eleventh gear 29, front axle input shaft S8, and front axle, providing traction to the front wheels.

[0038] During four-wheel drive traction operations, clutch 27 is usually disengaged, decoupling the front and rear axles. Each axle is driven independently by its own electric motor, dynamically adjusting its output speed and torque to ensure the theoretical speeds of the front and rear wheels are equal. This allows for full utilization of the traction force of both wheels, optimizing the overall traction efficiency. During steering, the front electric motor 34 outputs a faster speed, ensuring the theoretical speed of the front wheels is always greater than that of the rear wheels. This gives the front wheels a certain lead ratio, maintaining driving force and reducing the tendency for front wheel sideslip, thus facilitating steering.

[0039] like Figure 1 and Figure 2 As shown, during two-wheel drive transportation operations, both the mode switching clutch 22 and the normally engaged clutch 27 are disengaged, and the front motor 34 provides output power. The power of the front motor 34 is transmitted to the front wheels via the second spline sleeve, the front drive input shaft S7, the fifteenth gear 35, the eleventh gear 29, the front axle input shaft S8, and the front axle. The front wheels are used to provide two-wheel drive traction.

[0040] When the tractor brakes, the normally engaged clutch 27 engages, the mode switching clutch 22 disengages, and the front and rear axles connect. The braking torque generated by the slippage of the front wheels is transmitted to the service brake 20 via the front axle, front axle input shaft S8, eleventh gear 29, tenth gear 28, normally engaged clutch 27, normally engaged clutch input shaft S9, parking brake 26, normally engaged clutch intermediate shaft S9a, first spline sleeve 25, normally engaged clutch output shaft S9b, ninth gear 24, twelfth gear 30, small bevel shaft S6, small bevel gear 21, large bevel gear 19, and sun gear shaft 9. The braking torque generated by the slippage of the rear wheels is transmitted to the service brake 20 via the planetary carrier 11, double planetary pinion 10, double planetary gear 13, and sun gear shaft 9. Operating the service brake 20 generates a braking torque that balances the braking torque of the front and rear wheels, achieving four-wheel braking. Simultaneously, the front electric motor 34 is an integrated generator and motor. The braking torque generated by the slippage of the front wheels is also driven by the front axle, the front axle input shaft S8, the eleventh gear 29, the fifteenth gear 35, the front drive input shaft S7, and the second spline sleeve to rotate the front motor 34 to generate electricity and recover braking energy. The front motor 34 plays an auxiliary braking role.

[0041] When the tractor is stopped and the engine is turned off, clutch 27 is usually engaged, connecting the front and rear axles. When the tractor stops on a longitudinal slope, the front and rear wheels can simultaneously provide static friction torque. The static friction torque generated by the front wheels is transmitted to the parking brake 26 via the front axle, front axle input shaft S8, eleventh gear 29, tenth gear 28, normally engaged clutch 27, and normally engaged clutch input shaft S9. The static friction torque generated by the rear wheels is transmitted to the parking brake 26 via the planetary carrier 11, double planetary pinion 10, double planetary gear 13, sun gear shaft 9, large bevel gear 19, small bevel gear 21, small bevel shaft S6, twelfth gear 30, ninth gear 24, normally engaged clutch output shaft S9b, first spline sleeve 25, and normally engaged clutch intermediate shaft S9a. When the parking brake 26 is operated, a braking torque that balances the static friction torque of the front and rear wheels is generated on the parking brake 26, enabling the tractor to reliably park without slipping on a large longitudinal slope angle, thus improving the longitudinal stability of the tractor.

[0042] Of course, the present invention is not limited to the embodiments described above. Several other embodiments based on the design concept of the present invention are also provided below.

[0043] For example, in other embodiments, unlike the embodiments described above, the PTO clutch 14 is a multi-plate clutch.

[0044] For example, in other embodiments, unlike the embodiments described above, the mode switching clutch 22 is a wet clutch.

[0045] It should be noted that the above embodiments are only used to illustrate the present invention, but the present invention is not limited to the above embodiments. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A drive system for a hybrid tractor, comprising an engine (1), a generator (4), a front electric motor (34), and a rear electric motor (33), characterized in that, The engine (1) is connected to the generator (4) via the universal drive shaft (3). The generator (4) is connected to the PTO input shaft (S4) via the first gear transmission mechanism. The PTO input shaft (S4) is connected to the PTO transmission via the PTO clutch (14) and the second gear transmission mechanism arranged in sequence. It also includes a small cone shaft (S6), a sun gear shaft (9), a normally engaged clutch input shaft (S9), a rear axle, a front axle, and a front axle input shaft (S8) connected to the front axle. The front axle input shaft (S8) is equipped with an eleventh gear (29). The front motor (34) is connected to the eleventh gear (29) through the first transmission unit. The normally engaged clutch input shaft (S9) is equipped with a normally engaged clutch (27) and a tenth gear (28) that meshes with the eleventh gear (29). The normally engaged clutch input shaft (S9) is also connected in sequence to a parking brake (26), a normally engaged clutch intermediate shaft (S9a), a first spline sleeve (25), and a normally engaged clutch output shaft (S9b). The small cone shaft (S6) is equipped with an eighth gear (23) and a mode switching clutch (22). The rear motor (33) is connected to the eighth gear (23) through the second transmission unit. The output shaft (S9b) of the normally engaged clutch is connected to the small cone shaft (S6) through the third gear transmission mechanism. One end of the sun gear shaft (9) is connected to the rear wheel through a planetary gear mechanism, and the other end is connected to the differential. The small cone shaft (S6) is connected to the differential through a third transmission unit. A service brake (20) is provided on the sun gear shaft (9).

2. The drive system for a hybrid tractor according to claim 1, characterized in that, It also includes a torsional damper (2), one end of which is connected to the output end of the engine (1), and the other end is connected to the universal drive shaft (3).

3. The drive system for a hybrid tractor according to claim 1, characterized in that, The first gear transmission mechanism includes an idler shaft (S2), a pump drive shaft (S3), an input shaft (S1) connected to a generator (4), and a first gear (5) disposed on the input shaft (S1). The pump drive shaft (S3) is connected to a hydraulic pump (8). A third gear (7) is disposed on the pump drive shaft (S3). A second gear (6) is disposed on the idler shaft (S2) and meshes with the first gear (5) and the third gear (7). A thirteenth gear (31) is disposed on the PTO input shaft (S4) and meshes with the first gear (5) and the second gear (6).

4. The drive system for a hybrid tractor according to claim 3, characterized in that, The second gear transmission mechanism includes a fourth gear (15) and a fifth gear (16) connected to the PTO clutch (14), and also includes a sixth gear (17) and a seventh gear (18) connected to the PTO. The fourth gear (15) meshes with the seventh gear (18), the fifth gear (16) meshes with the sixth gear (17), and the PTO clutch (14) is located between the thirteenth gear (31) and the fourth gear (15).

5. A drive system for a hybrid tractor according to claim 1, characterized in that, The first transmission unit includes a front drive input shaft (S7) and a fifteenth gear (35) that meshes with the eleventh gear (29) on the front drive input shaft (S7). The output end of the front motor (34) is connected to the front drive input shaft (S7) through a second spline sleeve.

6. A drive system for a hybrid tractor according to claim 1, characterized in that, The parking brake (26) is located between the normally engaged clutch (27) and the first spline sleeve (25).

7. A drive system for a hybrid tractor according to claim 1, characterized in that, The second transmission unit includes a rear drive input shaft (S5) and a fourteenth gear (32) that meshes with the eighth gear (23) on the rear drive input shaft (S5). The output end of the rear motor (33) is connected to the rear drive input shaft (S5) through a third spline sleeve.

8. A drive system for a hybrid tractor according to claim 1, characterized in that, The third gear transmission mechanism includes a ninth gear (24) disposed on the output shaft (S9b) of the normally engaged clutch and a twelfth gear (30) disposed on the small cone shaft (S6) and meshing with the ninth gear (24).

9. A drive system for a hybrid tractor according to claim 1, characterized in that, The planetary gear mechanism includes a planet carrier (11), a double planetary gear and a gear ring (12). The double planetary gear includes a double planetary large gear (13) and a double planetary small gear (10) that are coaxially fixedly connected. The double planetary small gear (10) meshes with the gear ring (12), and the double planetary large gear (13) meshes with the sun gear of the sun gear shaft (9). The double planetary large gear (13) and the double planetary small gear (10) are connected to the rear wheel through the planet carrier (11).

10. A drive system for a hybrid tractor according to claim 1, characterized in that, The third transmission unit includes a small bevel gear (21) mounted on a small bevel shaft (S6), which meshes with a large bevel gear (19), and the large bevel gear (19) is connected to the sun gear shaft (9) via a differential.

Images