Power shifting gearbox

Abstract

The invention discloses a power gear shifting gearbox, and belongs to the technical field of new energy engineering machinery. Which comprises a box body (2), a speed reducing mechanism is arranged in the box body (2), and an output shaft (4) is arranged at the power output end of the speed reducing mechanism, and is characterized in that a high-speed gear set and a low-speed gear set are movably arranged on the output shaft (4), and the power output end of the speed reducing mechanism is connected with the high-speed gear set and the low-speed gear set; and the output shaft (4) is connected with the high-speed gear set or the low-speed gear set through the gear shifting mechanism (3). In the power gear shifting gearbox, the output shaft is connected with the high-speed gear set or the low-speed gear set through the gear shifting mechanism to complete gear shifting, the gear shifting mechanism only works in the gear shifting process, no extra energy is consumed after gear shifting is completed, and power consumption is reduced. A planetary gear train scheme is adopted for first-stage speed reduction of the power gear shifting gearbox, the reduction ratio is large, and the structure is compact.

Description

Technical Field

[0001] The present invention relates to the technical field of new energy engineering machinery, and in particular to a power shift gearbox. Background Art

[0002] With the development and application of new energy vehicle technology, related technologies such as lithium batteries, motors and their drivers have developed rapidly. In recent years, new energy technology has rapidly penetrated from the automotive field to the fields of engineering machinery and agricultural machinery, completing the electrification of medium-sized loaders, medium-sized excavators, and high-horsepower tractors. With the continuous development of electric engineering machinery and agricultural machinery, the use of electric motors and single-stage reduction transmissions of new energy vehicles can no longer meet the working requirements of "low-speed operation with large traction" and "transfer operation with high speed" for electric engineering machinery and agricultural machinery. In the existing technology, the drive of engineering machinery and agricultural machinery cannot get rid of the limitations of the gearbox, and the existing gearboxes used in engineering machinery and agricultural machinery are all developed and designed based on the working characteristics of the engine. Direct application to engineering machinery and agricultural machinery has problems such as low input speed, poor gear precision, low mechanical efficiency, and high noise.

[0003] With the continuous development of technology, some speed change solutions for construction machinery and agricultural machinery have also appeared on the market, such as: (1) The technical solution disclosed in the Chinese invention patent with application number 201410538136.8, application date October 13, 2014, and patent name “Electric drive system based on two-speed transmission and coordinated shift control method thereof”, in which the clutch and the brake are connected.

[0004] The drawback of this technical solution is that the hydraulic system is always in working state during operation, so the energy consumption is relatively high.

[0005] (2) The technical solution disclosed in the Chinese invention patent with application number 202311420633.3, application date October 30, 2023, and patent name “Gearbox for Electric Engineering Machinery and Electric Engineering Machinery”, in which the first gear friction pair group can selectively connect or disconnect the case and the inner gear ring, and the second gear friction pair group can selectively connect or disconnect the sun gear and the first output gear. Since the sun gear is indirectly meshed with the inner gear ring through the planetary gear, the sun gear and the inner gear ring are selectively connected to the first output gear respectively, so that switching between different gears can be achieved.

[0006] The defect of this technical solution is that it is necessary to set a first gear friction pair group and a second gear friction pair group for the first gear and the second gear respectively, and one of the first gear friction pair group and the second gear friction pair group is in a coupled state and the other is in a separated state during operation. Therefore, when this technical solution is implemented, it is always necessary to set up a set of continuously working hydraulic systems to keep the first gear friction pair group or the second gear friction pair group in a coupled state, which not only consumes high energy but also has a relatively complex structure.

[0007] (3) The technical solution disclosed in the Chinese invention patent with application number 202010884577.9, application date August 28, 2020, and patent name “An electronically controlled automatic transmission and method for construction machinery”, in which a reverse gear and first gear planetary gear train assembly connected by an overrunning clutch assembly is adopted; the reverse gear and first gear planetary gear train assembly includes a planetary gear train, a reverse gear friction plate group and a first gear friction plate group connected to the planetary gear train, a reverse gear piston connected to the reverse gear friction plate group, and a first gear piston connected to the first gear friction plate group; and when it is necessary to switch to the second gear, a special second gear assembly is also provided.

[0008] The drawback of this technical solution is that: when switching between the first gear and the second gear, a set of clutches needs to be set respectively, and a set of continuously working hydraulic systems needs to be set between the first gear and the reverse gear. Therefore, this technical solution also has the problems of high energy consumption and complex structure.

[0009] Therefore, designing a new gearbox with a simple structure and low energy consumption to meet the needs of engineering machinery and agricultural machinery gearboxes has become an urgent problem to be solved in this field. Summary of the invention

[0010] The technical problem to be solved by the present invention is: to overcome the shortcomings of the prior art and provide a power shift transmission that connects the output shaft to a high-speed gear set or a low-speed gear set through a shift mechanism to complete the shift, wherein the shift mechanism only works during the shift process and no additional energy is consumed after the shift is completed, thereby reducing power consumption.

[0011] The technical solution adopted by the present invention to solve its technical problem is: the power shift gearbox includes a housing, a reduction mechanism is arranged in the housing, and the power output end of the reduction mechanism is connected to the output shaft through a transmission component, and is characterized in that: the transmission component includes an intermediate transmission component, a high-speed gear set and a low-speed gear set, the high-speed gear set and the low-speed gear set are coaxially arranged with the output shaft, the intermediate transmission component is connected to the high-speed gear set or the low-speed gear set, and a shifting mechanism is also arranged, and the output shaft is connected to the high-speed gear set or the low-speed gear set through the shifting mechanism.

[0012] Preferably, the high-speed gear set and the low-speed gear set are both movably mounted on the outer ring of the output shaft.

[0013] Preferably, the intermediate transmission assembly includes an intermediate shaft, on which a low-speed intermediate shaft gear and a high-speed intermediate shaft gear are coaxially fixed, the low-speed intermediate shaft gear or the high-speed intermediate shaft gear is meshed with the gear at the power output end of the reduction mechanism, the low-speed intermediate shaft gear is meshed with the low-speed gear set, and the high-speed intermediate shaft gear is meshed with the high-speed gear set.

[0014] Preferably, a power intermediate gear is arranged between the low-speed gear set and the high-speed gear set, and the power intermediate gear is coaxially fixed with the output shaft. The shift mechanism includes a reciprocating coupling sleeve, which connects the low-speed gear set and the power intermediate gear, or connects the high-speed gear set and the power intermediate gear.

[0015] Preferably, the shift mechanism includes a piston mechanism, a shift fork is fixed on the piston rod of the piston mechanism, a coupling sleeve is fixed to the end of the shift fork, and the coupling sleeve is an inner gear ring that reciprocates between the low-speed gear set, the high-speed gear set and the power intermediate gear.

[0016] Preferably, the piston mechanism is a shift cylinder, the hydraulic mechanism is connected to the shift cylinder, and the piston rod is a drive shaft installed on the side of the piston body in the shift cylinder.

[0017] Preferably, the hydraulic mechanism includes a hydraulic pump, the inlet of the hydraulic pump is connected to the oil tank, the outlet of the hydraulic pump is connected to the inlet of the shift valve, the two outlets of the shift valve are connected to the high-speed shift pipeline and the low-speed shift pipeline respectively, the two sides of the piston body in the shift cylinder are respectively a high-speed cavity and a low-speed cavity, the high-speed shift pipeline is connected to the high-speed cavity, the low-speed shift pipeline is connected to the low-speed cavity, a high-speed drive overflow valve is connected in the high-speed shift pipeline, and a low-speed drive overflow valve is connected in the low-speed shift pipeline.

[0018] Preferably, an overflow port is also provided on the surface of the shift oil cylinder, the overflow port is connected to the oil tank through an overflow pipe, and the overflow port is connected to the high-speed cavity or the low-speed cavity as the piston moves.

[0019] Preferably, the reduction mechanism is a planetary gear mechanism, the power output end of the reduction mechanism is a driving gear fixed coaxially with the planet carrier in the planetary gear mechanism, a clutch for locking the outer gear ring is provided at the end of the planetary gear mechanism, and the clutch is fixed in the housing.

[0020] Preferably, a connecting disc is coaxially fixed to the end of the outer gear ring, and the connecting disc is connected to the clutch.

[0021] Compared with the prior art, the present invention has the following beneficial effects: In this power shift transmission, the output shaft is connected to the high-speed gear set or the low-speed gear set through a shift mechanism to complete the shift. The shift mechanism only works during the shift process and no additional energy is consumed after the shift is completed, thereby reducing power consumption.

[0022] In this power shift transmission, a connecting disc is provided at the end of the outer gear ring, and the outer gear ring is locked by connecting the connecting disc into the clutch. The connecting disc facilitates the setting of the clutch at the end of the planetary gear mechanism, thereby reducing the space occupied by the box.

[0023] The first stage reduction of the power shift transmission adopts a planetary gear system, which has a large reduction ratio and a compact structure.

[0024] This power shift gearbox is mainly developed for the field of new energy engineering machinery and agricultural machinery, filling the gap in the motor-driven mechanical operation gearbox in the field of engineering machinery and agricultural machinery. It solves the problem that a single motor-driven vehicle cannot simultaneously meet the mechanical working requirements of "low-speed operation with high traction" and "transfer operation with high speed".

[0025] This power shift gearbox can output torque in reverse, simplify the gearbox structure and greatly reduce the cost of the motor and its controller, giving full play to the advantages of electric motors in the fields of engineering machinery and agricultural machinery, and maximizing energy conservation and emission reduction.

[0026] This power shift gearbox has a multi-plate wet clutch and uses the physical characteristics of the planetary gear system to achieve power disconnection. The gear shift operation can be performed under any working condition of the machine. The gear shift impact is small, which greatly improves the reliability and service life of the gearbox. The hydraulic power shift mode is adopted, and the ingenious hydraulic system design is well matched. No hydraulic energy consumption is achieved when the gearbox is running and outputting power. With the gearbox controller algorithm, automatic shifting and manual and automatic integrated control can be achieved. Replacing the shift valve with a manual machine can achieve pure mechanical control. The control scheme is flexible and easy to control costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is the front view of the power shift transmission.

[0028] Figure 2 for Figure 1 Right view of .

[0029] Figure 3 Rear elevation view with case omitted for powershift transmission.

[0030] Figure 4 Rear isometric view with case omitted for powershift transmission.

[0031] Figure 5 for Figure 2 AA section view.

[0032] Figure 6 for Figure 4 Enlarged view of point A in the middle.

[0033] Figure 7 for Figure 5 Enlarged view of point B in the middle.

[0034] Figure 8 This is an axonometric view of the power shift transmission shift mechanism.

[0035] Fig. 9 This is a schematic diagram of the power transmission principle of the power shift transmission.

[0036] Fig.10 This is a schematic diagram of the power shift transmission shift oil circuit.

[0037] Among them: 1. driving motor; 2. housing; 3. shift mechanism; 4. output shaft; 5. brake disc; 6. brake piston; 7. driving gear; 8. planetary carrier; 9. outer gear ring; 10. connecting plate; 11. clutch; 12. low-speed middle shaft gear; 13. intermediate shaft; 14. driving shaft; 15. low-speed intermediate gear; 16. shift fork; 17. low-speed driving gear; 18. coupling sleeve; 19. high-speed driving gear; 20. high-speed intermediate gear; 21. high-speed middle shaft gear; 22. power intermediate gear; 23. clutch plate; 24. inner sleeve; 2 5. Shift cylinder; 26. Input shaft; 27. Clutch release valve; 28. Low-speed return line; 29. ​​Overflow pipe; 30. Piston body; 31. High-speed drive overflow valve; 32. Low-speed drive overflow valve; 33. High-speed shift line; 34. High-speed return line; 35. Low-speed shift line; 36. High-speed return overflow valve; 37. Low-speed return overflow valve; 38. Low-speed clutch drive line; 39. Shift valve; 40. Hydraulic pump; 41. Fuel tank; 42. Main line overflow valve; 43. High-speed clutch drive line; 44. Shift controller. DETAILED DESCRIPTION

[0038] Figures 1 to 10 The best embodiment of the present invention is shown below in conjunction with the attached Figures 1 to 10 The present invention is further described.

[0039] like Figure 1~2 As shown, a power shift transmission includes a housing 2, a driving motor 1 is installed on one side of the housing 2, and the motor shaft of the driving motor 1 is connected to the housing 2. An output shaft 4 is led out from the lower part of the housing 2, and the output shaft 4 passes through the housing 2. A brake disc 5 is coaxially fixed to one end of the output shaft 4, and a brake piston 6 is arranged on the upper part of the brake disc 5. The brake piston 6 is fixed to the side of the housing 2. The brake disc 5 is installed in the brake piston 6, and the brake piston 6 clamps the brake disc 5 when working, so as to brake the output shaft 4. A shift mechanism 3 of the power shift transmission is arranged on the upper part of the output shaft 4, and the gear position is changed by the shift mechanism 3.

[0040] Combination Figures 3-5 A planetary gear mechanism is provided in the housing 2, and the motor shaft of the driving motor 1 is used as the input shaft 26 (see Fig. 9) is connected to the planetary gear mechanism and is coaxially fixed with the wheel shaft of the sun gear in the planetary gear mechanism. A clutch 11 is arranged on the outside of the other end of the planetary gear mechanism. The clutch 11 is realized by a normally closed multi-plate wet clutch known in the art. The clutch 11 in this reducer serves as a transmission disengagement device between the outer gear ring 9 and the planet carrier 8, and is further combined with Figure 7 A connecting plate 10 is coaxially fixed on one side of the outer gear ring 9 close to the clutch 11 . After the connecting plate 10 enters the clutch 11 , it is coaxially fixed to the inner sleeve 24 in the clutch 11 .

[0041] When the clutch 11 is in a locked state, the clutch plate 23 is driven by the spring in the clutch 11, and the inner sleeve 24 is locked by the clutch plate 23. At this time, the outer ring gear 9 is further locked by the connecting plate 10. At this time, the planetary carrier 8 acts as the power end of the planetary gear mechanism to output the power chamber. When the clutch 11 is disengaged, the inner sleeve 24 is released, and the outer ring gear 9 is in a free state, and the planetary gear mechanism cannot transmit power.

[0042] Combination Fig. 9 A driving gear 7 is coaxially fixed on the side of the planetary carrier 8 close to the driving motor 1, and an intermediate shaft 13 is horizontally arranged below the planetary gear mechanism. A high-speed intermediate shaft gear 21 and a low-speed intermediate shaft gear 12 are coaxially fixed on the intermediate shaft 13, wherein the high-speed intermediate shaft gear 21 is meshed with the driving gear 7. When the planetary carrier 8 drives the driving gear 7 to rotate, the driving gear 7 drives the intermediate shaft 13 and the high-speed intermediate shaft gear 21 and the low-speed intermediate shaft gear 12 to rotate synchronously.

[0043] The output shaft 4 is arranged at the lower part of the intermediate shaft 13, and the low-speed intermediate gear 15, the low-speed driving gear 17, the high-speed driving gear 19 and the high-speed intermediate gear 20 are coaxially and rotatably arranged on the output shaft 4. The low-speed intermediate gear 15 and the low-speed driving gear 17 are double-linked gear structures, and the high-speed driving gear 19 and the high-speed intermediate gear 20 are double-linked gear structures. The high-speed intermediate shaft gear 21 meshes with the high-speed intermediate gear 20, the low-speed intermediate shaft gear 12 meshes with the low-speed intermediate gear 15, and the low-speed driving gear 17 and the high-speed driving gear 19 are arranged opposite to each other.

[0044] A power intermediate gear 22 is coaxially fixed on the output shaft 4. The power intermediate gear 22 is located between the low-speed driving gear 17 and the high-speed driving gear 19. The high-speed driving gear 19, the low-speed driving gear 17 and the power intermediate gear 22 have the same number of teeth, and the high-speed driving gear 19, the low-speed driving gear 17 and the power intermediate gear 22 are coaxially arranged. The shift mechanism 3 is located on the side between the intermediate shaft 13 and the output shaft 4. The power intermediate gear 22 is connected to the high-speed driving gear 19, or the power intermediate gear 22 is connected to the low-speed driving gear 17 through the shift mechanism 3.

[0045] Further integration Figure 6 as well as Figure 8 The shift mechanism 3 includes a shift cylinder 25, in which a reciprocating piston body 30 is arranged, and a drive shaft 14 led out from the shift cylinder 25 is connected to the piston body 30 in the shift cylinder 25. A shift fork 16 is fixed in the middle of the drive shaft 14, and a coupling sleeve 18 is clamped in the fork mouth of the shift fork 16. The coupling sleeve 18 is an inner gear ring structure, and the inner teeth of the coupling sleeve 18 are always meshed with the power intermediate gear 22. When the piston body 30 in the shift cylinder 25 is output, the drive shaft 14 is output from the shift cylinder 25, driving the coupling sleeve 18 to move toward the high-speed driving gear 19. At this time, the coupling sleeve 18 is simultaneously sleeved on the outside of the power intermediate gear 22 and the high-speed driving gear 19, connecting the power intermediate gear 22 with the high-speed driving gear 19; when the piston body 30 in the shift cylinder 25 is reset, the drive shaft 14 is reset, driving the coupling sleeve 18 to move toward the low-speed driving gear 17. At this time, the coupling sleeve 18 is simultaneously sleeved on the outside of the power intermediate gear 22 and the low-speed driving gear 17, connecting the power intermediate gear 22 with the low-speed driving gear 17.

[0046] The number of teeth of the high-speed intermediate shaft gear 21 is greater than that of the high-speed intermediate gear 20 , while the number of teeth of the low-speed intermediate shaft gear 12 is less than that of the low-speed intermediate gear 15 . When the power intermediate gear 22 is connected to the high-speed driving gear 19 through the coupling sleeve 18, the power is transmitted from the driving gear 7, the high-speed middle shaft gear 21, the high-speed intermediate gear 20 and the high-speed driving gear 19 to the power intermediate gear 22, and the output shaft 4 is driven to rotate by the power intermediate gear 22, and it is now in the high-speed gear position; when the power intermediate gear 22 is connected to the low-speed driving gear 17 through the coupling sleeve 18, although the high-speed intermediate gear 20 and the high-speed driving gear 19 are also driven by the high-speed middle shaft gear 21 to rotate, at this time, the high-speed intermediate gear 20 and the high-speed driving gear 19 are in an idling state, and the power output by the driving gear 7 is transmitted to the power intermediate gear 22 through the high-speed middle shaft gear 21, the intermediate shaft 13, the low-speed middle shaft gear 12, the low-speed intermediate gear 15 and the low-speed driving gear 17, and the output shaft 4 is driven to rotate by the power intermediate gear 22, and it is now in the low-speed gear position.

[0047] like Fig.10 As shown, the shift cylinder 25 and the clutch 11 are driven by a hydraulic system, which includes a hydraulic pump 40. The inlet of the hydraulic pump 40 is connected to the oil tank 41, and the outlet of the hydraulic pump 40 is connected to the shift valve 39 through a pipeline. A main line overflow valve 42 is installed on the connecting pipeline between the hydraulic pump 40 and the shift valve 39. The main line overflow valve 42 is implemented by a direct-acting overflow valve. The oil inlet of the main line overflow valve 42 is connected to the connecting pipeline between the hydraulic pump 40 and the shift valve 39, and the oil outlet of the main line overflow valve 42 returns to the oil tank 41 through a pipeline.

[0048] The shift valve 39 is implemented by a two-position three-way solenoid valve with one inlet and two outlets. The control coil of the shift valve 39 is connected to the shift controller 44. When the shift controller 44 (through the drive circuit) outputs a voltage signal to the control coil of the shift valve 39, the valve core of the shift valve 39 moves. The outlet of the hydraulic pump 40 is connected to the oil inlet of the shift valve 39 through a pipeline. The high-speed shift pipeline 33 and the high-speed clutch drive pipeline 43 are respectively led out from one of the oil outlets of the shift valve 39, and the low-speed shift pipeline 35 and the low-speed clutch drive pipeline 38 are respectively led out from the other oil outlet of the shift valve 39.

[0049] A clutch release valve 27 is provided, and the clutch release valve 27 is implemented by a two-position two-way solenoid valve. The other ends of the high-speed clutch drive pipeline 43 and the low-speed clutch drive pipeline 38 are respectively connected to the oil inlet of the clutch release valve 27, and the oil outlet of the clutch release valve 27 is connected to the oil cylinder of the clutch 11.

[0050] The high-speed shift pipeline 33 is led out from the shift valve 39 and connected to the oil inlet of the high-speed drive overflow valve 31. The high-speed drive overflow valve 31 is implemented by a direct-acting overflow valve, and the oil outlet of the high-speed drive overflow valve 31 is connected to the cylinder body of the shift cylinder 25 through a pipeline; the low-speed shift pipeline 35 is led out from the shift valve 39 and connected to the oil inlet of the low-speed drive overflow valve 32. The low-speed drive overflow valve 32 is also implemented by a direct-acting overflow valve, and the oil outlet of the low-speed drive overflow valve 32 is also connected to the cylinder body of the shift cylinder 25 through a pipeline. The oil outlets of the high-speed drive overflow valve 31 and the low-speed drive overflow valve 32 and the connection points with the cylinder body of the shift cylinder 25 are respectively located on both sides of the piston in the shift cylinder 25. For the convenience of description, the cavity where the high-speed drive overflow valve 31 and the cylinder body of the shift cylinder 25 are located is called the high-speed cavity of the shift cylinder 25, and the cavity where the low-speed drive overflow valve 32 and the cylinder body of the shift cylinder 25 are located is called the low-speed cavity of the shift cylinder 25. The cylinder body of the self-shift cylinder 25 is also provided with a cylinder overflow port, and an overflow pipe 29 is connected to the cylinder overflow port, and the other side of the overflow pipe 29 returns to the oil tank 41.

[0051] A high-speed reflux relief valve 36 and a low-speed reflux relief valve 37 are also provided, and both the high-speed reflux relief valve 36 and the low-speed reflux relief valve 37 are implemented by pilot relief valves. The oil inlet of the pilot valve body of the high-speed reflux relief valve 36 is connected to the high-speed shift pipeline 33, the oil inlet of the main valve body of the high-speed reflux relief valve 36 is connected to the connection pipeline between the low-speed drive relief valve 32 and the shift oil cylinder 25 through the high-speed reflux pipeline 34, and the oil outlet of the main valve body of the high-speed reflux relief valve 36 returns to the oil tank 41 through the pipeline; the oil inlet of the pilot valve body of the low-speed reflux relief valve 37 is connected to the low-speed shift pipeline 35, the oil inlet of the main valve body of the low-speed reflux relief valve 37 is connected to the connection pipeline between the high-speed drive relief valve 31 and the shift oil cylinder 25 through the low-speed reflux pipeline 28, and the oil outlet of the main valve body of the low-speed reflux relief valve 37 returns to the oil tank 41 through the pipeline.

[0052] The conduction pressures of the high-speed return relief valve 36 and the low-speed return relief valve 37 are both lower than the conduction pressures of the high-speed drive relief valve 31 and the low-speed drive relief valve 32. In the present power shift transmission, the conduction pressures of the high-speed return relief valve 36 and the low-speed return relief valve 37 are set to 2MPa, the conduction pressures of the high-speed drive relief valve 31 and the low-speed drive relief valve 32 are set to 3MPa, and the pressure in the clutch 11 driving the clutch 11 to separate is 2MPa.

[0053] The specific working process and working principle are as follows: The vehicle controller can automatically control upshift or downshift according to the pre-set logic (such as by vehicle speed), and the driver can manually upshift or downshift according to the actual situation through the shift button connected to the shift controller 44 or the vehicle controller. Regardless of whether it is in manual mode or automatic mode, when upshift is required, the shift controller 44 outputs a control signal (recorded as input drive voltage) to the shift valve 39, at which time the valve body in the shift valve 39 is actuated, connecting the hydraulic pump 40 to the high-speed clutch drive pipeline 43 (and the high-speed shift pipeline 33), and the hydraulic pump 40 simultaneously delivers hydraulic oil to the high-speed clutch drive pipeline 43 and the high-speed shift pipeline 33. The shift controller 44 also controls the clutch release valve 27 to operate, and the hydraulic oil further enters the cylinder of the clutch 11 through the clutch release valve 27, and at the same time, the hydraulic oil is delivered to the oil inlet of the high-speed drive relief valve 31 and the oil inlet of the pilot valve body of the high-speed return relief valve 36.

[0054] Since the conduction pressure of the high-speed drive overflow valve 31 is greater than the separation pressure of the clutch 11 and the conduction pressure of the pilot valve body of the high-speed return overflow valve 36, the clutch 11 and the high-speed return overflow valve 36 are both actuated before the high-speed drive overflow valve 31. At this time, when the clutch 11 is disengaged, the outer ring gear 9 is released and is in a free state. At this time, the planetary gear mechanism cannot transmit power. At the same time, the low-speed cavity in the shift cylinder 25 is connected to the oil tank 41 through the high-speed return overflow valve 36.

[0055] When the oil pressure output by the hydraulic pump 40 is greater than the conduction pressure of the high-speed driving relief valve 31, the high-speed driving relief valve 31 is conducted, and the hydraulic oil enters the high-speed cavity of the shift oil cylinder 25 through the high-speed driving relief valve 31, driving the piston of the shift oil cylinder 25 to move. During the movement of the piston in the shift oil cylinder 25, the hydraulic oil and air in the low-speed cavity of the shift oil cylinder 25 are discharged into the oil tank 41. With the movement of the piston in the shift oil cylinder 25, the drive shaft 14 is output from the shift oil cylinder 25. After the drive shaft 14 is in place, it drives the coupling sleeve 18 to move toward the side of the high-speed driving gear 19, and connects the high-speed driving gear 19 and the power intermediate gear 22.

[0056] After the piston of the shift cylinder 25 moves into position, the high-speed cavity in the shift cylinder 25 is connected to the overflow port, and the hydraulic oil output from the hydraulic pump 40 is instantly discharged into the oil tank 41 through the overflow pipe 29. At the same time, the hydraulic oil in the clutch 11 is withdrawn and discharged into the oil tank 41 through the overflow pipe 29. At this time, the clutch 11 locks the outer ring gear 9 of the planetary gear mechanism under the action of its internal spring, and the planetary gear mechanism can output power.

[0057] At this time, the outer ring gear 9 transmits power to the planetary carrier 8 through the clutch 11, and the planetary carrier 8 transmits power to the driving gear 7. The planetary carrier 8 drives the driving gear 7 to rotate, and the driving gear 7 transmits power to the high-speed intermediate gear 20 through the high-speed middle shaft gear 21. The high-speed intermediate gear 20 further transmits power to the power intermediate gear 22 through the high-speed driving gear 19 and the coupling sleeve 18. The power intermediate gear 22 drives the output shaft 4 to rotate. At this time, the low-speed driving gear 17 and the low-speed intermediate gear 15 idle on the outer ring of the output shaft 4, and the output shaft 4 is in the high-speed gear position, completing the upshift.

[0058] When downshifting is required, the shift controller 44 outputs a control signal (recorded as input drive voltage) to the shift valve 39. At this time, the valve body in the shift valve 39 is actuated to connect the hydraulic pump 40 to the low-speed shift pipeline 35 (and the low-speed clutch drive pipeline 38). The hydraulic pump 40 simultaneously delivers hydraulic oil to the low-speed shift pipeline 35 and the low-speed clutch drive pipeline 38. The shift controller 44 simultaneously controls the clutch release valve 27 to actuate, and the hydraulic oil further enters the cylinder body of the clutch 11 through the clutch release valve 27. At the same time, the hydraulic oil is delivered to the oil inlet of the low-speed drive relief valve 32 and the oil inlet of the pilot valve body of the low-speed return relief valve 37.

[0059] Since the conduction pressure of the low-speed drive relief valve 32 is greater than the separation pressure of the clutch 11 and the conduction pressure of the pilot valve body of the low-speed return relief valve 37, the clutch 11 and the low-speed drive relief valve 32 are both actuated before the low-speed drive relief valve 32. At this time, when the clutch 11 is disengaged, the outer ring gear 9 is released and is in a free state. At this time, the planetary gear mechanism cannot transmit power. At the same time, the high-speed cavity in the shift cylinder 25 is connected to the oil tank 41 through the low-speed return relief valve 37.

[0060] When the oil pressure output by the hydraulic pump 40 is greater than the conduction pressure of the low-speed driving relief valve 32, the low-speed driving relief valve 32 is conducted, and the hydraulic oil enters the low-speed cavity of the shift oil cylinder 25 through the low-speed driving relief valve 32, driving the piston of the shift oil cylinder 25 to move. During the movement of the piston in the shift oil cylinder 25, the hydraulic oil and air in the high-speed cavity of the shift oil cylinder 25 are discharged into the oil tank 41 through the low-speed return relief valve 37. With the movement of the piston in the shift oil cylinder 25, the drive shaft 14 is reset. After the drive shaft 14 is reset, it drives the coupling sleeve 18 to move toward the side of the low-speed driving gear 17 and connects the low-speed driving gear 17 and the power intermediate gear 22.

[0061] After the piston of the shift cylinder 25 moves into position, the low-speed chamber in the shift cylinder 25 is connected to the overflow port, and the hydraulic oil output from the hydraulic pump 40 is instantly discharged into the oil tank 41 through the overflow pipe 29. At the same time, the hydraulic oil in the clutch 11 is withdrawn and discharged into the oil tank 41 through the overflow pipe 29. At this time, the clutch 11 locks the outer ring gear 9 of the planetary gear mechanism under the action of its internal spring, and the planetary gear mechanism can output power.

[0062] At this time, the outer ring gear 9 transmits power to the planetary carrier 8 through the clutch 11, and the planetary carrier 8 drives the driving gear 7 to rotate. The driving gear 7 transmits power to the high-speed intermediate gear 20 through the high-speed intermediate shaft gear 21. The high-speed intermediate gear 20 further transmits power to the low-speed intermediate shaft gear 12 through the output shaft 4. The low-speed intermediate shaft gear 12 transmits power to the low-speed intermediate gear 15. The power is further transmitted to the power intermediate gear 22 through the low-speed driving gear 17 and the coupling sleeve 18. The power intermediate gear 22 drives the output shaft 4 to rotate. At this time, the high-speed driving gear 19 and the high-speed intermediate gear 20 are idling on the outer ring of the output shaft 4, and the output shaft 4 is in a low-speed gear position, completing the downshift.

[0063] The above is only a preferred embodiment of the present invention, and does not limit the present invention in other forms. Any technician familiar with the profession may use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. However, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention without departing from the technical solution of the present invention still belongs to the protection scope of the technical solution of the present invention.

Claims

1. A power shift transmission, comprising a housing (2), a reduction mechanism being arranged in the housing (2), a power output end of the reduction mechanism being connected to an output shaft (4) via a transmission assembly, and characterized in that: The transmission assembly comprises an intermediate transmission assembly, a high-speed gear set and a low-speed gear set, wherein the high-speed gear set and the low-speed gear set are coaxially arranged with the output shaft (4), the intermediate transmission assembly is connected to the high-speed gear set or the low-speed gear set, and a shift mechanism (3) is also provided, and the output shaft (4) is connected to the high-speed gear set or the low-speed gear set via the shift mechanism (3).

2. The power shift transmission according to claim 1, characterized in that: The high-speed gear set and the low-speed gear set are both movably mounted on the outer ring of the output shaft (4).

3. The power shift transmission according to claim 1, characterized in that: The intermediate transmission assembly comprises an intermediate shaft (13), on which a low-speed intermediate shaft gear (12) and a high-speed intermediate shaft gear (21) are coaxially fixed, the low-speed intermediate shaft gear (12) or the high-speed intermediate shaft gear (21) meshes with a gear at a power output end of the reduction mechanism, the low-speed intermediate shaft gear (12) meshes with a low-speed gear set, and the high-speed intermediate shaft gear (21) meshes with a high-speed gear set.

4. The power shift transmission according to any one of claims 1 to 3, characterized in that: A power intermediate gear (22) is provided between the low-speed gear set and the high-speed gear set. The power intermediate gear (22) is coaxially fixed with the output shaft (4). The shift mechanism (3) comprises a reciprocating coupling sleeve (18). The coupling sleeve (18) connects the low-speed gear set and the power intermediate gear (22), or connects the high-speed gear set and the power intermediate gear (22).

5. The power shift transmission according to claim 4, characterized in that: The shift mechanism (3) comprises a piston mechanism, a shift fork (16) is fixed on a piston rod of the piston mechanism, a coupling sleeve (18) is fixed on the end of the shift fork (16), and the coupling sleeve (18) is an inner gear ring that reciprocates between a low-speed gear set, a high-speed gear set and a power intermediate gear (22).

6. The power shift transmission according to claim 5, characterized in that: The piston mechanism is a shift oil cylinder (25), the hydraulic mechanism is connected to the shift oil cylinder (25), and the piston rod is a drive shaft (14) installed on the side of the piston body (30) in the shift oil cylinder (25).

7. The power shift transmission according to claim 6, characterized in that: The hydraulic mechanism comprises a hydraulic pump (40), the inlet of the hydraulic pump (40) is connected to an oil tank (41), the outlet of the hydraulic pump (40) is connected to the inlet of a shift valve (39), the two outlets of the shift valve (39) are connected to a high-speed shift pipeline (33) and a low-speed shift pipeline (35) respectively, the two sides of the piston body (30) in the shift oil cylinder (25) are respectively a high-speed cavity and a low-speed cavity, the high-speed shift pipeline (33) is connected to the high-speed cavity, the low-speed shift pipeline (35) is connected to the low-speed cavity, the high-speed drive relief valve (31) is connected to the high-speed shift pipeline (33), and the low-speed drive relief valve (32) is connected to the low-speed shift pipeline (35).

8. The power shift transmission according to claim 6, characterized in that: An overflow port is also provided on the surface of the shift oil cylinder (25). The overflow port is connected to the oil tank (41) via an overflow pipe (29). The overflow port is connected to the high-speed chamber or the low-speed chamber as the piston moves.

9. The power shift transmission according to claim 1 or 3, characterized in that: The speed reduction mechanism is a planetary gear mechanism, the power output end of the speed reduction mechanism is a driving gear (7) coaxially fixed with a planet carrier (8) in the planetary gear mechanism, a clutch (11) for locking an outer gear ring (9) is provided at the end of the planetary gear mechanism, and the clutch (11) is fixed in the housing (2).

10. The power shift transmission according to claim 9, characterized in that: A connecting disc (10) is coaxially fixed to the end of the outer gear ring (9), and the connecting disc (10) is connected to the clutch (11).

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