Hydraulic control system for a tractor hybrid transmission

Abstract

The application discloses a tractor hybrid power gearbox hydraulic control system, comprising an oil supply unit, a clutch hydraulic control unit and a gear hydraulic control unit, wherein the oil supply unit comprises an oil storage tank and a high-pressure oil pump for supplying oil to a pressure oil circuit; the clutch hydraulic control unit comprises a first clutch and a second clutch, the engagement or disengagement of the first clutch can be controlled through a first clutch control valve, and the engagement or disengagement of the second clutch can be controlled through a second clutch control valve; the gear hydraulic control unit comprises a first synchronizer, a second synchronizer and a third synchronizer, the first synchronizer or the second synchronizer can be controlled to switch between different gears through a first synchronizer control valve and a second synchronizer control valve, and whether the third synchronizer is enabled can be controlled through a third synchronizer control valve. The application can solve the technical problems of the existing hybrid power gearbox, such as harsh clutch engagement and fixed gear mode.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of agricultural vehicle gearbox technology, in particular to a tractor hybrid power gearbox hydraulic control system. BACKGROUND

[0002] As an agricultural production tool, the tractor has a complex and changeable working environment. The driver needs to switch gears according to the type of work, road conditions and other factors. The gearbox switches the gear ratio according to the driver's selected gear to adapt to changes in load or driving resistance, ensuring the power, fuel economy and driving comfort of the tractor.

[0003] The quality of gear shifting depends on two aspects: one is the engagement quality of the clutch during the shifting process, and the other is the accurate selection control of the synchronizer hydraulic control system. At present, tractors using hybrid power have three working conditions: engine independent driving, motor independent driving, and engine and motor hybrid driving. The existing gearbox suitable for hybrid power not only has a harsh clutch engagement, but also has a rigid switching and coordination between multiple power sources. There are only a few fixed driving modes, especially for engine and motor hybrid driving state. The shifting requirements of hybrid driving state are different from those of traditional DCT, AMT and other transmissions. It is necessary to control multiple clutches and synchronizers in the gearbox to realize the timely intervention of the motor according to the load of the tractor. SUMMARY

[0004] The purpose of the present application is to provide a tractor hybrid power gearbox hydraulic control system that can solve the technical problems of harsh clutch engagement and fixed driving mode of existing hybrid power gearboxes.

[0005] In order to achieve the above purpose, the present application adopts the following technical solutions.

[0006] A tractor hybrid power gearbox hydraulic control system includes an oil supply unit, a clutch hydraulic control unit and a gear shifting hydraulic control unit. The oil supply unit includes an oil tank and a high-pressure oil pump for supplying oil to the pressure oil circuit.

[0007] The clutch hydraulic control unit includes a first clutch for engaging the first / third gear with the engine and a second clutch for engaging the second / fourth gear with the engine. The first clutch is connected to the pressure oil circuit through a first clutch control valve, which can control the engagement or disengagement of the first clutch. The second clutch is connected to the pressure oil circuit through a second clutch control valve, which can control the engagement or disengagement of the second clutch.

[0008] The shift hydraulic control unit comprises a first synchronizer for switching between first gear and third gear, a second synchronizer for switching between second gear and fourth gear, and a third synchronizer for switching between fifth gear and reverse gear, wherein the fifth gear and the reverse gear are driven by the motor.

[0009] The first synchronizer and the second synchronizer are connected to the pressure oil circuit through the first synchronizer control valve and the second synchronizer control valve, and the first synchronizer or the second synchronizer can be controlled to switch between different gears through the first synchronizer control valve and the second synchronizer control valve. A first reversing valve is arranged between the synchronizer and the synchronizer control valve for switching the control object.

[0010] The third synchronizer is connected to the pressure oil circuit through the third synchronizer control valve, and the third synchronizer can be controlled to be enabled or disabled through the third synchronizer control valve. A second reversing valve is arranged between the third synchronizer and the third synchronizer control valve for controlling the third synchronizer to switch between the fifth gear and the reverse gear.

[0011] Further, the second reversing valve is a hydraulic reversing valve, and the control oil circuit of the second reversing valve is connected to the outlets of the first synchronizer control valve and the second synchronizer control valve, so that when the first synchronizer and the second synchronizer are disconnected from the pressure oil circuit, the second reversing valve is switched to a position for controlling the third synchronizer to engage the reverse gear.

[0012] Further, the oil supply unit further comprises a low-pressure oil pump for lubricating and cooling the gearbox. The high-pressure oil pump is coaxially connected to the low-pressure oil pump. The inlets of the high-pressure oil pump and the low-pressure oil pump are connected to the oil tank through the first filter. The outlet of the low-pressure oil pump is connected to the radiator. The outlet of the radiator is connected to the lubricating oil circuit through the second filter. A pressure limiting valve is arranged on the lubricating oil circuit.

[0013] Further, a bypass valve is arranged at the second filter.

[0014] Further, a buffer device is arranged between the clutch and the clutch control valve for relieving and absorbing the impact and vibration generated when the clutch is engaged.

[0015] Further, the buffer device comprises a pressure sensor, an electromagnetic ball valve and an accumulator. The pressure sensor is used to monitor the oil pressure in the clutch reset oil cylinder. The accumulator is connected to the reset oil cylinder inlet pipeline through the electromagnetic ball valve. The hydraulic oil can be controlled to enter or exit the accumulator through the electromagnetic valve.

[0016] Further, the high-pressure oil pump is connected to the pressure oil circuit through the third filter. An overflow valve is arranged on the pressure oil circuit.

[0017] Further, a bypass valve is arranged at the third filter.

[0018] Further, the first clutch control valve, the second clutch control valve, the first synchronization control valve, the second synchronization control valve, the third synchronization control valve and the first reversing valve are all solenoid valves.

[0019] Further, the first clutch control valve, the second clutch control valve, the first synchronization control valve, the second synchronization control valve, the third synchronization control valve are all two-position three-way valves, and the first reversing valve is a two-position nine-way valve.

[0020] After the above technical solution is adopted, the present application has the following beneficial effects:

[0021] 1. In the present application, the engine part and the motor part adopt independent synchronizers, and the working states of different synchronizers are controlled separately, so that the engine driving mode, the motor driving mode or the hybrid driving mode can be flexibly switched, and the driving mode can be flexibly adjusted according to the change of load.

[0022] 2. The present application is provided with a buffer device in front of the clutch, and the hydraulic oil is divided into the accumulator in the initial stage of clutch engagement and is released from the accumulator in the rear stage of clutch engagement by controlling the electromagnetic ball valve, so that the slow-to-fast engagement process of the clutch is realized, and the vibration caused by the large speed difference of the clutch friction plate can be absorbed in the initial stage of engagement, so that the clutch is stably combined.

[0023] 3. The present application is also provided with a lubricating and cooling unit for cooling and actively lubricating the mechanical parts of the gearbox, so that the long-term stable operation of the gearbox is ensured. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is the overall structure schematic diagram of the present application.

[0025] Figure 2 is the state schematic diagram when the first gear of the present application works alone.

[0026] Figure 3 is the state schematic diagram when the second gear of the present application works alone.

[0027] Figure 4 is the state schematic diagram when the third gear of the present application works alone.

[0028] Figure 5 is the state schematic diagram when the fourth gear of the present application works alone.

[0029] Figure 6 is the state schematic diagram when the fifth gear of the present application works alone.

[0030] Figure 7 is the state schematic diagram when the reverse gear of the present application works.

[0031] Figure 8 is the state schematic diagram when the first gear and the fifth gear of the present application work in hybrid driving mode.

[0032] Figure 9 is the state diagram of the present application when the two-gear and five-gear hybrid drive is in use.

[0033] BRIEF DESCRIPTION OF DRAWINGS: 1, oil supply unit, 111, high-pressure oil pump, 112, low-pressure oil pump, 12, oil tank, 131, first filter, 132, second filter, 133, third filter, 14, radiator, 15, pressure limiting valve, 16, overflow valve, 17, bypass valve, 2, clutch hydraulic control unit, 211, first clutch, 212, second clutch, 221, first clutch control valve, 222, second clutch control valve, 23, buffer device, 231, pressure sensor, 232, electromagnetic ball valve, 233, accumulator, 24, reset oil cylinder, 3, gear shift hydraulic control unit, 311, first synchronizer, 312, second synchronizer, 313, third synchronizer, 321, first synchronization control valve, 322, second synchronization control valve, 323, third synchronization control valve, 331, first reversing valve, 332, second reversing valve. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical scheme and advantages of the present application more clear, the characteristics and performance of the tractor hybrid power transmission gearbox hydraulic control system of the present application are further described in detail below in combination with the drawings and examples.

[0035] Please refer to the accompanying Figure 1 , a tractor hybrid power transmission gearbox hydraulic control system, comprising an oil supply unit 1, a clutch hydraulic control unit 2 and a gear shift hydraulic control unit 3.

[0036] The oil supply unit 1 comprises an oil tank 12 and a high-pressure oil pump 111 for supplying oil to the pressure oil circuit, and further comprises a low-pressure oil pump 112 for lubricating and cooling the gearbox. The high-pressure oil pump 111 is a small-flow high-pressure pump, and the low-pressure oil pump 112 is a large-flow low-pressure pump.

[0037] The high-pressure oil pump 111 is coaxially connected with the low-pressure oil pump 112, and the inlets of the high-pressure oil pump 111 and the low-pressure oil pump 112 are connected to the oil tank 12 through the first filter 131, which is used for primary filtering of impurities in the oil.

[0038] The high-pressure oil pump 111 is connected to the pressure oil circuit through the third filter 133, and the pressure oil circuit is provided with an overflow valve 16 for preventing the pressure in the pressure oil circuit from exceeding the limit value.

[0039] The outlet of the low-pressure oil pump 112 is connected to the radiator 14, and the outlet of the radiator 14 is connected to the lubricating oil circuit through the second filter 132. The lubricating oil circuit is provided with a pressure limiting valve 15 for maintaining the pressure of the oil in the oil circuit at 0-3 bar.

[0040] The second filter 132 and the third filter 133 are each provided with a bypass valve 17 for temporarily passing the oil through the bypass valve when the filter is blocked to prevent the pressure from exceeding the limit value.

[0041] The clutch hydraulic control unit 2 includes a first clutch 211 for engaging the first / third gear with the engine and a second clutch 212 for engaging the second / fourth gear with the engine. The first clutch 211 and the second clutch 212 are each driven to engage and disengage by a respective return oil cylinder 24. When the first clutch 211 is engaged, the driving shaft corresponding to the first / third gear is connected with the engine to rotate with the crankshaft, and when the second clutch 212 is engaged, the driving shaft corresponding to the second / fourth gear is connected with the engine to rotate with the crankshaft.

[0042] The first clutch 211 is connected to the pressure oil passage through a first clutch control valve 221, and the engagement or disconnection of the first clutch 211 can be controlled through the first clutch control valve 221. The second clutch 212 is connected to the pressure oil passage through a second clutch control valve 222, and the engagement or disconnection of the second clutch 212 can be controlled through the second clutch control valve 222. The first clutch control valve 221 and the second clutch control valve 222 are both two-position three-way solenoid valves.

[0043] A buffer device 23 for relieving and absorbing the impact and vibration generated when the clutch is engaged is provided between the clutch and the clutch control valve. The buffer device 23 includes a pressure sensor 231 for monitoring the oil pressure in the clutch return oil cylinder 24, an electromagnetic ball valve 232, and an accumulator 233 connected to the return oil cylinder 24 through the electromagnetic ball valve 232. The hydraulic oil can enter or exit the accumulator 233 through the electromagnetic valve.

[0044] In the initial stage of engagement of the clutch, the electromagnetic ball valve 232 is in a state that allows hydraulic oil to enter the accumulator 233. In the initial stage of engagement, the driving and driven friction plates in the clutch will generate a large impact due to the large speed difference. The impact is transmitted to the accumulator 233 through the return oil cylinder 24 and hydraulic oil. Due to the buffering effect of the accumulator 233, the impact generated by the engagement of the clutch friction plates can be effectively reduced. In the middle stage of engagement of the clutch, the speed difference between the driving and driven friction plates decreases, and the impact generated also decreases. When the pressure sensor 231 detects that the pressure in the return oil cylinder 24 reaches a certain value, the electromagnetic ball valve 232 is switched to a state that allows hydraulic oil to exit the accumulator 233, which accelerates the engagement speed of the clutch, avoids a long sliding time that generates a large sliding friction work, and reduces the service life of the clutch.

[0045] The shift hydraulic control unit 3 includes a first synchronizer 311 for switching between first gear and third gear, a second synchronizer 312 for switching between second gear and fourth gear, and a third synchronizer 313 for switching between fifth gear and reverse gear, both of which are driven by the motor. The synchronizer is connected to the corresponding driving shaft in the circumferential direction by shifting the corresponding synchronizer gear, so as to realize the gear shifting of the gearbox.

[0046] The first synchronizer 311 and the second synchronizer 312 are connected to the pressure oil circuit through the first synchronizer control valve 321 and the second synchronizer control valve 322. The first synchronizer 311 or the second synchronizer 312 can be switched between different gears by the first synchronizer control valve 321 and the second synchronizer control valve 322. The first synchronizer control valve 321 and the second synchronizer control valve 322 are both two-position three-way solenoid valves, and the first reversing valve 331 is a two-position nine-way solenoid valve.

[0047] The third synchronizer 313 is connected to the pressure oil circuit through the third synchronizer control valve 323. The third synchronizer 313 can be enabled or disabled by the third synchronizer control valve 323. The third synchronizer 313 and the third synchronizer control valve 323 are connected through the second reversing valve 332, which is used to control the switching of the third synchronizer 313 between the fifth gear and the reverse gear. The third synchronizer control valve 323 is a two-position three-way solenoid valve.

[0048] The second reversing valve 332 is a hydraulic reversing valve. The control oil circuit of the second reversing valve 332 is connected to the outlets of the first synchronizer control valve 321 and the second synchronizer control valve 322, so as to switch the second reversing valve 332 to the position for controlling the third synchronizer 313 to engage the reverse gear when the first synchronizer 311 and the second synchronizer 312 are both disconnected from the pressure oil circuit.

[0049] In practice, the tractor driver selects the appropriate gear according to the type of work. Since the first gear to the fourth gear are driven by the engine, in order to keep the engine in the appropriate power range, the transmission ratio of the first gear to the fourth gear increases in turn. Generally, the first gear and the second gear are used in high-load scenarios, and the third gear and the fourth gear are used in medium-load scenarios. The fifth gear and the reverse gear are driven by the motor. The fifth gear is used in light-load scenarios, and the reverse gear is used in scenarios that require reversing. The transmission ratio of the fifth gear and the reverse gear is determined according to the motor characteristics and the application scenario.

[0050] Embodiment one

[0051] When the driver selects the first gear, as shown in FIG. 1, the first gear is connected first. In the shift hydraulic control unit 3, the first reversing valve 331 is in the left position, the control object is the first synchronizer 311, and the second synchronizer 312 is in the reset state. Figure 2

[0052] First, connect the gear. In the shift hydraulic control unit 3, the first reversing valve 331 is in the left position, the control object is the first synchronizer 311, and the second synchronizer 312 is in the reset state.​

[0053] The first synchronization control valve 321 switches to the left position, the second synchronization control valve 322 is in the right position, and the hydraulic oil in the pressure oil circuit enters the first synchronizer 311 corresponding to one end of the first gear through the first synchronization control valve 321 and the first reversing valve 331, so that the first synchronizer 311 drives the corresponding synchronization gear, and the first gear is fixed in the circumferential direction with the output shaft of the first clutch 211.

[0054] The third synchronization control valve 323 is in the right position, and the third synchronizer 313 is in the reset state.

[0055] The clutch is engaged again. In the clutch hydraulic control unit 2, the first clutch control valve 221 switches to the left position, so that the first clutch 211 is communicated with the pressure oil circuit, and the hydraulic oil enters the reset oil cylinder 24 corresponding to the first clutch 211 to drive the first clutch 211 to engage. The second clutch control valve 222 is in the right position, so that the second clutch 212 is in the disengaged state.

[0056] After the first clutch 211 is engaged, the power of the engine drives the first gear to rotate synchronously through the first clutch 211, so that the tractor is driven at the first gear.

[0057] Example two

[0058] When the driver selects the second gear, as shown in Figure 3 .

[0059] First, connect the gear. In the gear hydraulic control unit 3, the first reversing valve 331 switches to the right position, and the control object is the second synchronizer 312, and the first synchronizer 311 is in the reset state.

[0060] The first synchronization control valve 321 switches to the left position, the second synchronization control valve 322 is in the right position, and the hydraulic oil in the pressure oil circuit enters the second synchronizer 312 corresponding to one end of the second gear through the first synchronization control valve 321 and the first reversing valve 331, so that the second synchronizer 312 drives the corresponding synchronization gear, and the second gear is fixed in the circumferential direction with the output shaft of the second clutch 212.

[0061] The third synchronization control valve 323 is in the right position, and the third synchronizer 313 is in the reset state.

[0062] The clutch is engaged again. In the clutch hydraulic control unit 2, the second clutch control valve 222 switches to the left position, so that the second clutch 212 is communicated with the pressure oil circuit, and the hydraulic oil enters the reset oil cylinder 24 corresponding to the second clutch 212 to drive the second clutch 212 to engage. The first clutch control valve 221 is in the right position, so that the first clutch 211 is in the disengaged state.

[0063] After the second clutch 212 is engaged, the power of the engine drives the second gear synchronously through the second clutch 212, and the tractor is driven by the second gear.

[0064] Example Three

[0065] When the driver selects the third gear, as shown in FIG. 3, the first clutch 211 is disengaged, the second clutch 212 is engaged, and the third gear is connected. Figure 4

[0066] First, the gear is connected. In the gear hydraulic control unit 3, the first reversing valve 331 is in the left position, and the control object is the first synchronizer 311. The second synchronizer 312 is in the reset state.

[0067] The second synchronization control valve 322 is switched to the left position, and the first synchronization control valve 321 is in the right position. The hydraulic oil in the pressure oil circuit enters the corresponding end of the first synchronizer 311 and the third gear through the second synchronization control valve 322 and the first reversing valve 331, so that the first synchronizer 311 drives the corresponding synchronization gear, and the third gear is fixed in the circumferential direction with the output shaft of the first clutch 211.

[0068] The third synchronization control valve 323 is in the right position, and the third synchronizer 313 is in the reset state.

[0069] Second, the clutch is engaged. In the clutch hydraulic control unit 2, the first clutch control valve 221 is switched to the left position, so that the first clutch 211 is in communication with the pressure oil circuit, and the hydraulic oil enters the corresponding reset oil cylinder 24 of the first clutch 211 to drive the first clutch 211 to engage. The second clutch control valve 222 is in the right position, so that the second clutch 212 is in the disengaged state.

[0070] After the first clutch 211 is engaged, the power of the engine drives the third gear synchronously through the first clutch 211, and the tractor is driven by the third gear.

[0071] Example Four

[0072] When the driver selects the fourth gear, as shown in FIG. 4, the first clutch 211 is disengaged, the second clutch 212 is engaged, and the fourth gear is connected. Figure 5

[0073] First, the gear is connected. In the gear hydraulic control unit 3, the first reversing valve 331 is switched to the right position, and the control object is the second synchronizer 312. The first synchronizer 311 is in the reset state.

[0074] The second synchronization control valve 322 is switched to the left position, and the first synchronization control valve 321 is in the right position. The hydraulic oil in the pressure oil circuit enters the corresponding end of the second synchronizer 312 and the fourth gear through the second synchronization control valve 322 and the first reversing valve 331, so that the second synchronizer 312 drives the corresponding synchronization gear, and the fourth gear is fixed in the circumferential direction with the output shaft of the second clutch 212.

[0075] ​​The third synchronizer control valve 323 is in the right position, and the third synchronizer 313 is in the reset state.

[0076] The clutch is engaged. In the clutch hydraulic control unit 2, the second clutch control valve 222 is switched to the left position, so that the second clutch 212 is communicated with the pressure oil path, and the hydraulic oil enters the reset oil cylinder 24 corresponding to the second clutch 212, driving the second clutch 212 to engage. The first clutch control valve 221 is in the right position, so that the first clutch 211 is in the disengaged state.

[0077] After the second clutch 212 is engaged, the power of the engine drives the four-gear synchronously through the second clutch 212, realizing that the tractor is driven by the four-gear.

[0078] Example five

[0079] When the driver selects the five-gear, as shown in Figure 6 .

[0080] The gear is connected first. In the gear hydraulic control unit 3, the first reversing valve 331 is in the left position, and the control object is the first synchronizer 311, and the second synchronizer 312 is in the reset state.

[0081] The first synchronizer control valve 321 and the second synchronizer control valve 322 are both switched to the left position, and the hydraulic oil in the pressure oil path enters the two ends of the first synchronizer 311 through the first synchronizer control valve 321 and the second synchronizer control valve 322 at the same time, so that the pressure of the two ends of the first synchronizer 311 is balanced, and the first synchronizer 311 is still in the reset state.

[0082] The second selection valve 332 is controlled by the pressure at the outlet of the first synchronizer control valve 321 and the second synchronizer control valve 322, and is in the left position, that is, the position of the third synchronizer 313 engaged into the five-gear. The third synchronizer control valve 323 is switched to the left position, and the hydraulic oil in the pressure oil path enters the end corresponding to the five-gear of the third synchronizer 313 through the third synchronizer control valve 323 and the second selection valve 332, so that the third synchronizer 313 drives the corresponding synchronizer gear, and the five-gear is fixed in the circumferential direction of the output shaft of the motor.

[0083] Since the five-gear is driven independently by the motor, in the clutch hydraulic control unit 2, the first clutch control valve 221 and the second clutch control valve 222 are both in the right position, so that the first clutch 211 and the second clutch 212 are both in the disengaged state.

[0084] The power of the motor drives the five-gear synchronously, realizing that the tractor is driven by the five-gear. At this time, the engine can be stopped, or the generator is driven to charge the power battery.

[0085] Example six

[0086] When the driver selects the reverse gear, as shown in Figure 7 .

[0087] First connection gear. In the gear hydraulic control unit 3, the first synchronization control valve 321 and the second synchronization control valve 322 are both in the right position, and the first synchronizer 311 and the second synchronizer 312 are both in the reset state.

[0088] Since there is no pressure at the outlet of the first synchronization control valve 321 and the second synchronization control valve 322, the second selection valve 332 is in the right position, that is, the position of controlling the third synchronizer 313 to engage into reverse gear. The third synchronization control valve 323 is switched to the left position, and the hydraulic oil in the pressure oil circuit enters the third synchronizer 313 corresponding to the reverse gear through the third synchronization control valve 323 and the second selection valve 332, so that the third synchronizer 313 drives the corresponding synchronization gear, and the reverse gear is fixed in the circumferential direction with the output shaft of the motor.

[0089] Since the reverse gear is driven by the motor independently, in the clutch hydraulic control unit 2, the first clutch control valve 221 and the second clutch control valve 222 are both in the right position, so that the first clutch 211 and the second clutch 212 are both in the disengaged state.

[0090] The power of the motor drives the reverse gear to rotate synchronously, realizing the driving of the tractor in reverse with the reverse gear. At this time, the engine can be stopped or drive the generator to charge the power battery.

[0091] Example seven

[0092] Since the working environment of the tractor is mostly on non-paved roads such as fields, the ground state is variable and undulating, and the running resistance changes in a large range. When the tractor is running in first gear, if the load is suddenly increased, the system automatically uses the hybrid drive mode and calls the motor and the engine to drive simultaneously.

[0093] As shown in Figure 8 Based on the gearbox in first gear, at this time the second selection valve 332 is controlled by the pressure at the outlet of the first synchronization control valve 321 and is in the left position, that is, the position of controlling the third synchronizer 313 to engage into fifth gear.

[0094] Switch the third synchronization control valve 323 to the left position, and the hydraulic oil in the pressure oil circuit enters the third synchronizer 313 corresponding to the fifth gear through the third synchronization control valve 323 and the second selection valve 332, so that the third synchronizer 313 drives the corresponding synchronization gear, and the fifth gear is fixed in the circumferential direction with the output shaft of the motor.

[0095] At this time, the power of the motor drives the fifth gear to rotate synchronously, intervenes in the driving of the tractor, provides additional power, and improves the output power of the tractor. Due to the great power range and fast response ability of the motor, it can intervene in driving in time when the load of the tractor changes suddenly, so that the engine can maintain a stable operating condition and improve fuel economy.

[0096] Example 8

[0097] When the tractor is running in second gear and a sudden increase in load is detected, the system automatically activates the hybrid drive mode, calling on the motor and engine to drive simultaneously.

[0098] like Figure 9 As shown, based on the transmission being in the second gear, the second selector valve 332 is controlled by the pressure at the outlet of the first synchronization control valve 321 to be in the left position, that is, the third synchronizer 313 is controlled to be in the fifth gear.

[0099] Switch the third synchronous control valve 323 to the left position, and the hydraulic oil in the pressure oil circuit enters the end of the third synchronizer 313 corresponding to the fifth gear through the third synchronous control valve 323 and the second selection valve 332, so that the third synchronizer 313 shifts the corresponding synchronous gear, circumferentially fixing the fifth gear and the output shaft of the motor.

[0100] At this time, the power of the motor drives the five-speed gear to rotate synchronously, intervening in the drive of the tractor, providing additional power and increasing the output power of the tractor.

[0101] Example 9

[0102] When the tractor is running in third to fifth gear and a sudden increase in load is detected, the system prompts the operator to downshift to increase the tractor's traction.

[0103] It should be noted that the gear names in the accompanying drawings are represented by Roman numerals and letters, but based on common sense, it can be clearly understood that gear I, gear II, gear III, gear IV, gear V and gear R correspond to gear 1, gear 2, gear 3, gear 4, gear 5 and reverse gear respectively.

[0104] It should be further explained that the parts not described in detail in this solution are all prior art, and 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 modifications made to the above embodiments based on the technical essence of the present invention fall within the scope of protection of the present invention.

Claims

1. A tractor hybrid transmission hydraulic control system, comprising an oil supply unit (1), a clutch hydraulic control unit (2) and a shift hydraulic control unit (3), characterized in that: The oil supply unit (1) comprises an oil storage tank (12) and a high-pressure oil pump (111) for supplying oil to a pressure oil circuit, The clutch hydraulic control unit (2) comprises a first clutch (211) for engaging the first / third gear with the engine and a second clutch (212) for engaging the second / fourth gear with the engine, the first clutch (211) is connected to the pressure oil circuit through a first clutch control valve (221), the engagement or disengagement of the first clutch (211) can be controlled through the first clutch control valve (221), the second clutch (212) is connected to the pressure oil circuit through a second clutch control valve (222), the engagement or disengagement of the second clutch (212) can be controlled through the second clutch control valve (222), A buffer device (23) is arranged between the clutch and the clutch control valve for relieving and absorbing the impact and vibration generated when the clutch is engaged, The buffer device (23) comprises a pressure sensor (231), an electromagnetic ball valve (232) and an accumulator (233), the pressure sensor (231) is used to monitor the oil pressure in the clutch reset oil cylinder (24), the accumulator (233) is connected to the reset oil cylinder (24) through the electromagnetic ball valve (232), and the hydraulic oil can be controlled to enter or discharge from the accumulator (233) through the electromagnetic valve, The gear hydraulic control unit (3) comprises a first synchronizer (311) for switching the first / third gear, a second synchronizer (312) for switching the second / fourth gear, and a third synchronizer (313) for switching the fifth gear / reverse gear, the fifth gear / reverse gear is driven by an electric motor, The first synchronizer (311) and the second synchronizer (312) are connected to the pressure oil circuit through a first synchronization control valve (321) and a second synchronization control valve (322), the first synchronization control valve (321) and the second synchronization control valve (322) can control the first synchronizer (311) or the second synchronizer (312) to switch between different gears, and a first reversing valve (331) is arranged between the synchronizer and the synchronization control valve for switching the control object, The third synchronizer (313) is connected to the pressure oil circuit through a third synchronization control valve (323), and the third synchronization control valve (323) can control whether the third synchronizer (313) is enabled, a second reversing valve (332) is arranged between the third synchronizer (313) and the third synchronization control valve (323) for controlling the third synchronizer (313) to switch between the fifth gear / reverse gear, The second reversing valve (332) is a hydraulic reversing valve, the control oil circuit of the second reversing valve (332) is communicated with the outlets of the first synchronization control valve (321) and the second synchronization control valve (322), and when the first synchronizer (311) and the second synchronizer (312) are disconnected from the pressure oil circuit, the second reversing valve (332) is switched to a position for controlling the third synchronizer (313) to engage the reverse gear.

2. A hydraulic control system for a tractor hybrid transmission as set forth in claim 1, characterized in that: The oil supply unit (1) further comprises a low-pressure oil pump (112) for lubricating and cooling the gearbox, the high-pressure oil pump (111) is coaxially connected with the low-pressure oil pump (112), the high-pressure oil pump (111) and the low-pressure oil pump (112) are connected with the oil tank (12) through the first filter (131), the outlet of the low-pressure oil pump (112) is connected with the radiator (14), the outlet of the radiator (14) is connected with the lubricating oil circuit through the second filter (132), and the lubricating oil circuit is provided with a pressure limiting valve (15).

3. A hydraulic control system for a tractor hybrid transmission as set forth in claim 1, characterized in that: The high-pressure oil pump (111) is connected with the pressure oil circuit through the third filter (133), and the pressure oil circuit is provided with an overflow valve (16).

4. A hydraulic control system for a tractor hybrid transmission as set forth in claim 1, characterized in that: The first clutch control valve (221), the second clutch control valve (222), the first synchronization control valve (321), the second synchronization control valve (322) and the third synchronization control valve (323) are all electromagnetic valves.

5. A hydraulic control system for a tractor hybrid transmission as set forth in claim 4, characterized in that: The first clutch control valve (221), the second clutch control valve (222), the first synchronization control valve (321), the second synchronization control valve (322) and the third synchronization control valve (323) are all two-position three-way valves, and the first reversing valve (331) is a two-position nine-way valve.

6. A hydraulic control system for a tractor hybrid transmission as set forth in claim 2, characterized in that: A bypass valve (17) is arranged at the second filter (132).

7. A hydraulic control system for a tractor hybrid transmission as set forth in claim 3, wherein: A bypass valve (17) is arranged at the third filter (133).

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