Power transmission system and electric engineering vehicle

Abstract

The utility model relates to the technical field of electric vehicles, in particular to a power transmission system and an electric engineering vehicle, the power transmission system comprises a first box body, a first transmission mechanism and a driving mechanism, and the first box body is provided with a first mounting cavity; the first transmission mechanism is arranged in the first mounting cavity and comprises at least two first driving gears, a first input gear and a first output gear set, the at least two first driving gears are engaged with the first input gear, and the first input gear is in transmission connection with the first output gear set; the driving mechanism comprises at least two first drivers, and the at least two first drivers are in transmission connection with the at least two first driving gears in a one-to-one correspondence mode. The motion state of the electric engineering vehicle is adjusted by controlling the working number of the first drivers, the output torque of the first drivers and the rotating direction of the corresponding first driving gear. The problems of gear shifting impact, power interruption, high safety coefficient of required gears and space waste of a gearbox of a power transmission system are solved.

Description

Technical Field

[0001] This utility model relates to the field of electric vehicle technology, and in particular to power transmission systems and electric engineering vehicles. Background Technology

[0002] As a core component of electric engineering vehicles, the powertrain system typically includes an electric motor and a gearbox. Its function is to match torque and speed through multi-stage gear sets, thereby adapting to the power output requirements under complex working conditions. Traditional powertrain systems (such as manual transmission (MT), automatic transmission (AT), and dual-clutch transmission (DCT)) rely on mechanical or hydraulic shifting mechanisms to switch gear sets, and their performance directly affects the overall transmission efficiency, reliability, and driving comfort of the vehicle.

[0003] Currently, the mainstream powertrain shifting mechanisms are mainly based on the following two types of technologies:

[0004] Synchronizer shifting technology: The gears mesh after rotating at the same speed through friction bevel surfaces, but the synchronization process depends on the precise operation of the driver or electronic control system;

[0005] Clutch-linked shifting technology (such as DCT): It uses the alternating engagement of dual clutches to achieve uninterrupted power transmission, but it has extremely high requirements for control logic and hardware precision.

[0006] Although the above technologies are relatively mature, the following key bottlenecks still exist:

[0007] Shift shock: During gear meshing, if the speed difference is not fully synchronized, a violent impact will occur between the tooth surfaces, resulting in vibration and noise, which will affect driving smoothness and gear life.

[0008] Power interruption: Traditional manual transmissions and some automatic transmissions need to briefly cut off power transmission during gear shifts (such as clutch disengagement), resulting in power output interruption. This causes a noticeable jerk, especially in construction machinery or heavy-duty electric construction vehicles, reducing operating comfort.

[0009] High safety factor requirement: In order to withstand the instantaneous overload caused by shifting impact, the existing gear design needs to significantly improve the safety factor (such as increasing the module and strengthening the tooth surface hardness), which leads to an increase in gear size and weight, and an increase in manufacturing cost;

[0010] Space waste and decreased reliability: Large gears occupy too much space in the power transmission system, limiting the compact design of the power transmission system; at the same time, frequent impacts can still easily cause failure problems such as pitting and tooth breakage, resulting in high maintenance costs.

[0011] Therefore, a power transmission system is urgently needed to solve the above problems. Utility Model Content

[0012] The purpose of this utility model is to provide a power transmission system and an electric engineering vehicle to solve the problems of existing power transmission systems in related technologies, such as shift shock, power interruption, the need to significantly improve the safety factor of gear design, and large-size gears occupying too much space in the power transmission system, thus limiting the compact design of the power transmission system.

[0013] On the one hand, this utility model provides a power transmission system, which includes:

[0014] A first housing, wherein the first housing is provided with a first mounting cavity;

[0015] A first transmission mechanism is disposed in the first mounting cavity and includes at least two first driving gears, a first input gear and a first output gear set. The at least two first driving gears respectively mesh with the first input gear, and the first input gear is connected to the first output gear set in a transmission manner.

[0016] The drive mechanism includes at least two first drivers, each of which is connected to at least two first drive gears in a one-to-one correspondence.

[0017] As a preferred technical solution for the power transmission system, both the first driving gear and the first input gear are helical gears.

[0018] As a preferred technical solution for the power transmission system, there are two first driving gears, which are respectively located on both sides of the first input gear.

[0019] As a preferred technical solution for the power transmission system, the first output gear set includes a first driven shaft and a first driven gear. The first driven shaft rotates around the axis of the first driven shaft and is rotatably engaged with the first housing. The first driven gear and the first input gear are sleeved on the first driven shaft.

[0020] The first driven gear is coaxially fixed to the first driven shaft, and the first input gear is coaxially fixed to the first driven gear, or the first input gear is coaxially fixed to the first driven shaft, and the first driven gear is coaxially fixed to the first input gear.

[0021] As a preferred technical solution for power transmission systems, it also includes:

[0022] The second housing has a second mounting cavity;

[0023] The second transmission mechanism is disposed in the second mounting cavity and includes a second driving gear, a second input gear and a second output gear set. The second driving gear and the second input gear mesh, and the second input gear is connected to the second output gear set in a transmission manner.

[0024] The drive mechanism further includes a second driver, which is connected to the second drive gear.

[0025] As a preferred technical solution for the power transmission system, the second housing is positioned above the first housing along the direction of gravity, the bottom wall of the second housing is provided with an oil passage, the top wall of the first housing is provided with a connection port, and the oil passage is connected to the connection port;

[0026] It also includes an oil suction pump. The bottom of the first housing is provided with an oil outlet, and the top of the second housing is provided with an oil inlet. The oil inlet of the oil suction pump is connected to the oil outlet, and the oil outlet of the oil suction pump is connected to the oil inlet.

[0027] As a preferred technical solution for the power transmission system, the first housing and the second housing are detachably connected.

[0028] As a preferred technical solution for the power transmission system, the second output gear set includes a second driven gear and at least two transfer gears. The second driven gear is coaxially fixed to the second input gear, and the at least two transfer gears mesh with the second driven gear respectively.

[0029] As a preferred technical solution for the power transmission system, the second housing is positioned above the first housing along the direction of gravity, the bottom wall of the second housing is provided with an oil passage, the top wall of the first housing is provided with a connection port, and the oil passage is connected to the connection port;

[0030] It also includes an oil suction pump. The bottom of the first housing is provided with an oil outlet, and the top of the second housing is provided with an oil inlet. The oil inlet of the oil suction pump is connected to the oil outlet, and the oil outlet of the oil suction pump is connected to the oil inlet. The input shaft of the oil suction pump is connected to one of the at least two drive gears.

[0031] On the other hand, this utility model provides an electric engineering vehicle, including the power transmission system of any of the above-mentioned solutions.

[0032] The beneficial effects of this utility model are as follows:

[0033] This utility model provides a power transmission system and an electric engineering vehicle. The power transmission system includes a first housing, a first transmission mechanism, and a drive mechanism. The first housing has a first mounting cavity. The first transmission mechanism is disposed in the first mounting cavity and includes at least two first driving gears, a first input gear, and a first output gear set. The at least two first driving gears mesh with the first input gears respectively, and the first input gears are drive-connected to the first output gear set. The drive mechanism includes at least two first drivers, each corresponding to one of the at least two first driving gears. When the electric engineering vehicle equipped with this power transmission system is in motion, based on the vehicle's own load and the forward or reverse command received, the system controls the number of working first drivers, the output torque of the working first drivers, and the rotation direction of the corresponding first driving gears, so that the power transmission system outputs appropriate torque and the correct power direction. This solves the problems of shift shock, power interruption, the need for significantly improved safety factors in gear design, and the excessive space occupied by large gears in the power transmission system, which limits the compact design of the power transmission system. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the power transmission system in an embodiment of the present invention (light load forward mode);

[0035] Figure 2 This is a schematic diagram of the power transmission system in an embodiment of the present invention (light load reverse mode);

[0036] Figure 3 This is a schematic diagram of the power transmission system in an embodiment of the present invention (heavy-load forward mode);

[0037] Figure 4 This is a schematic diagram of the power transmission system in an embodiment of the present invention (heavy-load reverse mode);

[0038] Figure 5 This is a schematic diagram of the power transmission system in an embodiment of the present utility model;

[0039] Figure 6 This is a partial cross-sectional view of the power transmission system in an embodiment of this utility model.

[0040] In the picture:

[0041] G, direction of gravity;

[0042] 1. First housing; 11. First mounting cavity; 12. Connection port; 13. Oil outlet;

[0043] 21. First driving gear; 22. First input gear; 231. First driven shaft; 232. First driven gear; 24. Output gear;

[0044] 31. First driver; 32. Second driver;

[0045] 4. Second housing; 41. Second mounting cavity; 42. Oil flow channel; 43. Oil inlet;

[0046] 51. Second driving gear; 52. Second input gear; 531. Second driven gear; 532. Transfer gear; 533. Second driven shaft;

[0047] 6. Oil suction pump. Detailed Implementation

[0048] The technical solution of this utility model will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this utility model. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this utility model.

[0049] In the description of this utility model, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this utility model and for 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. Therefore, they should not be construed as limitations on this utility model. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. The terms "first position" and "second position" refer to two different positions. Moreover, "above," "on top of," and "over" the first feature in relation to the second feature includes the first feature directly above and diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "under," and "below" the first feature in relation to the second feature includes the first feature directly below and diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0050] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0051] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0052] like Figures 1-6 As shown, this embodiment provides a power transmission system, which includes a first housing 1, a first transmission mechanism, and a drive mechanism. The first housing 1 is provided with a first mounting cavity 11. The first transmission mechanism is disposed in the first mounting cavity 11 and includes at least two first drive gears 21, a first input gear 22, and a first output gear set. The at least two first drive gears 21 respectively mesh with the first input gears 22, and the first input gears 22 are drive-connected to the first output gear set. The drive mechanism includes at least two first drivers 31, and the at least two first drivers 31 are drive-connected to the at least two first drive gears 21 in a one-to-one correspondence. When the electric engineering vehicle equipped with this power transmission system is in motion, the first drivers 31 can drive the corresponding first drive gears 21 to rotate. Since the first drive gears 21 mesh with the first input gears 22, they drive the first input gears 22 to rotate, thereby transmitting power to the first output gear set. The first output gear set is connected to the vehicle's running system to realize the vehicle's forward and reverse movement.

[0053] To enable the vehicle to adapt to different operating modes, such as light-load forward mode, light-load reverse mode, heavy-load forward mode, and heavy-load reverse mode, the system controls the number of first drive units 31 in operation, as well as the output torque of the first drive unit 31 and the rotation direction of the corresponding first drive gear 21, based on the electric engineering vehicle's own load and the forward or reverse command received by the electric engineering vehicle. This ensures that the power transmission system outputs torque and power in a direction compatible with the electric engineering vehicle's operating mode. This solves the problems of gearbox shift shock, power interruption, the need for significantly improved safety factors in gear design, and the excessive space occupied by large gears in the power transmission system, which limits the compact design of the power transmission system.

[0054] Specifically, the non-operating first driver 31 is in a follower state, and thus the shaft of the non-operating first driver 31 is driven by its corresponding first drive gear 21.

[0055] Optionally, the first driver 31 is a motor.

[0056] Optionally, both the first driving gear 21 and the first input gear 22 are helical gears. In this embodiment, compared with spur gears, the tooth surface contact line of helical gears is oblique or spiral, and the contact gradually enters or exits during meshing, reducing impact and vibration, and making the transmission process smoother; the overlap ratio of helical gears can reach 2-3 (spur gears are only 1-2), which extends the number of teeth participating in meshing at the same time, reduces the load on a single tooth, improves the transmission continuity, and improves the overall load-bearing capacity and service life.

[0057] Optionally, two first drive gears 21 are provided, with each first drive gear 21 positioned on either side of the first input gear 22. In this embodiment, one first driver 31 operates to rotate the corresponding first drive gear 21 forward, enabling the vehicle to move forward, while the other first driver 31 operates to rotate the corresponding first drive gear 21 in reverse, enabling the vehicle to move backward. This arrangement ensures that the two first drive gears 21 are always in contact with the tip of the tooth of the first input gear 22, resulting in smooth meshing and uniform stress distribution. If the two first drive gears 21 are positioned on one side of the first input gear 22, the root of the tooth of one drive gear 21 will become the main contact area with the first input gear 22, which can easily lead to local stress concentration during meshing and potentially increased wear. To improve the service life of the first drive gears 21 and the first input gear 22, the two first drive gears 21 are positioned on either side of the first input gear 22. This arrangement can improve the service life of the first transmission mechanism when the electric engineering vehicle is operating under light load.

[0058] Optionally, the axis of the first input gear 22 is coplanar with the axes of the two first driving gears 21.

[0059] Optionally, the first output gear set includes a first driven shaft 231 and a first driven gear 232. The first driven shaft 231 is rotatably engaged with the first housing 1 around its axis. The first driven gear 232 and the first input gear 22 are sleeved on the first driven shaft 231. The first driven gear 232 is coaxially fixed to the first driven shaft 231, and the first input gear 22 is coaxially fixed to the first driven gear 232. In this embodiment, coaxially fixing the first input gear 22 and the first driven gear 232 can further reduce the axial dimension of the first transmission mechanism along the first driven shaft 231.

[0060] For the coaxial connection of the first driven gear 232 and the first driven shaft 231, optionally, the first driven gear 232 and the first driven shaft 231 are coaxially connected by a pin connection. In other embodiments, the first driven gear 232 and the first driven shaft 231 can also be coaxially connected by welding.

[0061] Optionally, for the connection between the first input gear 22 and the first driven gear 232, the first input gear 22 is provided with a plurality of first flange holes spaced apart circumferentially, and the first driven gear 232 is provided with a plurality of second flange holes spaced apart circumferentially. The plurality of first flange holes and the plurality of second flange holes correspond one-to-one, and a plurality of flange bolts are passed through the plurality of first flange holes and the plurality of second flange holes in a corresponding manner. The plurality of flange bolts are screwed into a plurality of nuts in a corresponding manner, so as to achieve coaxial fixation of the first input gear 22 and the first driven gear 232.

[0062] Optionally, the first output gear set further includes a first output gear 24, which meshes with a first driven gear 232, and the first output gear 24 is used to provide power to the vehicle's running system.

[0063] In other embodiments, the first input gear 22 is coaxially fixed to the first driven shaft 231, and the first driven gear 232 is coaxially fixed to the first input gear 22.

[0064] Optionally, the power transmission system further includes a second housing 4 and a second transmission mechanism. The second housing 4 is provided with a second mounting cavity 41. The second transmission mechanism is disposed in the second mounting cavity 41 and includes a second drive gear 51, a second input gear 52, and a second output gear set. The second drive gear 51 and the second input gear 52 mesh, and the second input gear 52 is drive-connected to the second output gear set. The drive mechanism further includes a second driver 32, which is drive-connected to the second drive gear 51. In this embodiment, the output end of the second output gear set is the vehicle's PTO port, providing a power source for the vehicle's transmission pump, steering pump, and working pump. Optionally, the second driver 32 is an electric motor.

[0065] Optionally, the second housing 4 is positioned above the first housing 1 along the direction of gravity G. The bottom wall of the second housing 4 is provided with an oil passage 42, and the top wall of the first housing 1 is provided with a connection port 12. The oil passage 42 is connected to the connection port 12. The power transmission system also includes an oil suction pump 6. The bottom of the first housing 1 is provided with an oil outlet 13, and the top of the second housing 4 is provided with an oil inlet 43. The oil inlet of the oil suction pump 6 is connected to the oil outlet 13, and the oil outlet of the oil suction pump 6 is connected to the oil inlet 43. In this embodiment, the oil suction pump 6 draws lubricating oil from the oil outlet 13 in the first housing 1 and pumps it into the top oil inlet 43 of the second housing 4. After the lubricating oil enters the second mounting cavity 41 and lubricates the second transmission mechanism, it flows to the oil passage 42 under the action of gravity and then enters the first mounting cavity 11 to lubricate the first transmission mechanism in the first mounting cavity 11. In summary, the oil suction pump 6 can realize the reciprocating circulation of lubricating oil in the first mounting cavity 11 and the second mounting cavity 41 to lubricate the first and second transmission mechanisms.

[0066] Optionally, the oil passage 42 and the top wall of the first housing 1 are sealed by a sealing ring to achieve a seal between the oil passage 42 and the connection port 12, so as to prevent lubricating oil from leaking out from the gap between the oil passage 42 and the connection port 12.

[0067] Optionally, the first housing 1 and the second housing 4 are detachably connected. In this embodiment, the first housing 1 and the second housing 4 are fixedly connected by bolts. In other embodiments, the first housing 1 and the second housing 4 can also be fixed by snap-fit ​​or riveting.

[0068] Optionally, the second output gear set includes a second driven gear 531 and at least two transfer gears 532. The second driven gear 531 is coaxially fixed to the second input gear 52, and the at least two transfer gears 532 mesh with the second driven gear 531 respectively. In this embodiment, the at least two transfer gears 532 can transmit the obtained power to the transmission pump, steering pump, oil suction pump 6, and working pump to provide a power source. The second driven gear 531 and the second input gear 52 are connected by a second driven shaft 533. The assembly method of the second driven gear 531, the second input gear 52, and the second driven shaft 533 is the same as the assembly method of the first driven gear 232, the first input gear 22, and the first driven shaft 231, and will not be described again here.

[0069] Optionally, the input shaft of the oil pump 6 is drive-connected to one of at least two drive gears 532. This arrangement requires the second drive 32 to be started before the first drive 31 can operate, so that the oil pump 6 can be powered and operated, thereby lubricating the first transmission mechanism and enabling it to function properly. In other embodiments, the oil pump 6 can also be an independently operating electric pump whose input shaft is not drive-connected to the drive gears 532. This arrangement allows the oil pump 6 to operate before the first transmission mechanism operates, without needing to start the second drive 32.

[0070] This utility model provides an electric engineering vehicle, including the power transmission system described above. The output shaft of the power transmission system is connected to the running gear of the electric engineering vehicle.

[0071] For the working mode of the power transmission system, exemplarily (taking the example of having two first drive gears 21, with the two first drive gears 21 respectively located on both sides of the first input gear 22):

[0072] Light load forward mode

[0073] One side's first driver 31 drives the corresponding first drive gear 21 to rotate in a forward direction, which in turn drives the first input gear 22, the first driven gear 232, and the first output gear 24 in sequence. The first output gear 24 provides power to the vehicle's running gear system to enable the vehicle to move forward. At this time, the other side's first driver 31 is in a follow-up state, and the specific output method is as follows: Figure 1 As shown.

[0074] Light load back mode

[0075] On the other side, the first driver 31 drives the corresponding first driving gear 21 to rotate in the reverse direction, which in turn drives the first input gear 22, the first driven gear 232, and the first output gear 24 in sequence. The first output gear 24 provides power to the vehicle's running gear system to enable the vehicle to reverse. At this time, the first driver 31 on one side is in a follow-up state, and the specific output method is as follows: Figure 2 As shown.

[0076] Heavy load forward mode

[0077] One side's first driver 31 drives the corresponding first drive gear 21 to rotate in a forward direction, which in turn drives the first input gear 22, the first driven gear 232, and the first output gear 24 in sequence. The first output gear 24 provides power to the vehicle's running gear to enable the vehicle to move forward. At this time, the other side's first driver 31 is in a follow-up state. When the output torque of one side's first driver 31 is greater than a preset value 'a', the other side's first driver 31 drives the corresponding first drive gear 21 to rotate in a forward direction, so that the two first drivers 31 share the output torque proportionally. The entire process is smooth and shock-free, achieving optimal comfort. The specific output method is as follows: Figure 3 As shown. The preset value 'a' is 800 Nm-2000 Nm, preferably 1000 Nm.

[0078] Heavy load back mode

[0079] On the other side, the first driver 31 drives the corresponding first drive gear 21 to rotate in the reverse direction, thereby sequentially driving the first input gear 22, the first driven gear 232, and the first output gear 24. The first output gear 24 provides power to the vehicle's running system to enable the vehicle to reverse. At this time, the first driver 31 on one side is in a follow-up state. When the output torque of the first driver 31 on the other side is greater than a preset value 'a', the first driver 31 on one side drives the corresponding first drive gear 21 to rotate in the reverse direction, so that the two first drivers 31 share the output torque proportionally. The entire process is smooth and shock-free, achieving optimal comfort. The specific output method is as follows: Figure 4 As shown. The preset value 'a' is 800 Nm-2000 Nm, preferably 1000 Nm.

[0080] Obviously, the above embodiments of this utility model are merely examples for clearly illustrating the present utility model, and are not intended to limit the implementation of the present utility model. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this utility model should be included within the protection scope of the claims of this utility model.

Claims

1. A power transmission system, characterized in that, include: The first housing (1) is provided with a first mounting cavity (11); The first transmission mechanism is disposed in the first mounting cavity (11) and includes at least two first drive gears (21), a first input gear (22) and a first output gear set. The at least two first drive gears (21) respectively mesh with the first input gears (22), and the first input gears (22) are connected to the first output gear set in a transmission connection. The drive mechanism includes at least two first drivers (31), each of which is connected to at least two first drive gears (21) in a transmission manner.

2. The power transmission system according to claim 1, characterized in that, Both the first driving gear (21) and the first input gear (22) are helical gears.

3. The power transmission system according to claim 2, characterized in that, There are two first driving gears (21), which are respectively located on both sides of the first input gear (22).

4. The power transmission system according to claim 1, characterized in that, The first output gear set includes a first driven shaft (231) and a first driven gear (232). The first driven shaft (231) rotates around the axis of the first driven shaft (231) in a rotatable engagement with the first housing (1). The first driven gear (232) and the first input gear (22) are sleeved on the first driven shaft (231). The first driven gear (232) is coaxially fixed to the first driven shaft (231), and the first input gear (22) is coaxially fixed to the first driven gear (232), or the first input gear (22) is coaxially fixed to the first driven shaft (231), and the first driven gear (232) is coaxially fixed to the first input gear (22).

5. The power transmission system according to claim 1, characterized in that, Also includes: The second housing (4) is provided with a second mounting cavity (41); The second transmission mechanism is disposed in the second mounting cavity (41) and includes a second drive gear (51), a second input gear (52) and a second output gear set. The second drive gear (51) and the second input gear (52) mesh, and the second input gear (52) is connected to the second output gear set in a transmission manner. The drive mechanism further includes a second driver (32), which is connected to the second drive gear (51) in a transmission connection.

6. The power transmission system according to claim 5, characterized in that, The second box (4) is positioned above the first box (1) along the direction of gravity (G). The bottom wall of the second box (4) is provided with an oil passage (42), and the top wall of the first box (1) is provided with a connection port (12). The oil passage (42) is connected to the connection port (12). It also includes an oil suction pump (6), with an oil outlet (13) at the bottom of the first housing (1) and an oil inlet (43) at the top of the second housing (4). The oil inlet of the oil suction pump (6) is connected to the oil outlet (13), and the oil outlet of the oil suction pump (6) is connected to the oil inlet (43).

7. The power transmission system according to claim 6, characterized in that, The first housing (1) and the second housing (4) are detachably connected.

8. The power transmission system according to claim 5, characterized in that, The second output gear set includes a second driven gear (531) and at least two transfer gears (532). The second driven gear (531) is coaxially fixed to the second input gear (52), and the at least two transfer gears (532) mesh with the second driven gear (531) respectively.

9. The power transmission system according to claim 8, characterized in that, The second box (4) is positioned above the first box (1) along the direction of gravity (G). The bottom wall of the second box (4) is provided with an oil passage (42), and the top wall of the first box (1) is provided with a connection port (12). The oil passage (42) is connected to the connection port (12). It also includes an oil suction pump (6), the bottom of the first housing (1) is provided with an oil outlet (13), the top of the second housing (4) is provided with an oil inlet (43), the oil inlet of the oil suction pump (6) is connected to the oil outlet (13), the oil outlet of the oil suction pump (6) is connected to the oil inlet (43), and the input shaft of the oil suction pump (6) is connected to one of the at least two drive gears (532).

10. An electric engineering vehicle, characterized in that, Includes the power transmission system as described in any one of claims 1-9.

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