Double-pump hydraulic system of automatic transmission and control method of double-pump hydraulic system

Abstract

The invention discloses a double-pump hydraulic system of an automatic transmission and a control method of the double-pump hydraulic system, and solves the problem that pressure oil with different requirements required by different modules in an existing hydraulic system of an automatic transmission of agricultural machinery is difficult to meet the requirements through twice pressure reduction of a single oil pump. The hydraulic system specifically comprises a transmission working hydraulic system, a transmission service braking hydraulic system and an oil tank. The transmission working hydraulic system comprises a first oil inlet way, a first gear pump, a safety valve, a first oil filter, a main pressure regulating overflow valve, an oil cooler, a plurality of clutch execution units and a parking brake execution unit, wherein the clutch execution units and the parking brake execution unit are arranged in front of the main pressure regulating overflow valve. The double-pump design is adopted, pressure oil with different oil pressure values and flows and large difference is provided, and it is guaranteed that the working states of the two systems are stable and reliable; the double pumps share the bottom oil pool in the transmission shell, so that the space of the box body is saved; the oil in the oil pool is circularly supplemented by a plurality of oil return paths, so that the oil suction quantity of double pumps can be met, and the oil pumps are prevented from sucking air at the same time.

Description

Technical Field

[0001] The invention relates to a transmission hydraulic control system, and in particular to an automatic transmission dual-pump hydraulic system and a control method thereof. Background Art

[0002] In the automatic transmission of large agricultural harvesting machinery, the hydraulic control system is the core module that enables the automatic transmission to achieve automatic gear shifting. The hydraulic control system of the automatic transmission of agricultural harvesting machinery mainly consists of two parts: the transmission working hydraulic system and the transmission service brake hydraulic system. The oil pressure of the transmission working hydraulic system is about 30 bar and the flow rate is about 30L / min; while the oil pressure of the transmission service brake hydraulic system is about 70 bar and the flow rate is about 16L / min. If a gear pump is used to provide pressure oil, and a pressure drop of 40Bar is achieved through two-stage pressure reduction, and the pressure oil flow required by the two hydraulic systems is maintained without large fluctuations, it is difficult to achieve oil supply with a single pump in reality.

[0003] Chinese patent CN111425593A discloses a 6-speed agricultural machinery transmission hydraulic system. However, for agricultural harvesting machinery hydraulic systems, multiple gears do not have many application scenarios, and a 2-gear design can already meet the crop harvesting scenario: 1st gear works in a field working mode of 0-15km / h; 2nd gear works in a road transfer mode of 0-35km / h. Summary of the invention

[0004] The purpose of the present invention is to solve the technical problems that the transmission working system and service brake system of the existing agricultural machinery automatic transmission hydraulic system are difficult to meet the working conditions of the respective hydraulic modules through two decompressions of a single pump, or the existing 6-speed agricultural machinery transmission hydraulic system cannot meet the actual application scenarios of agricultural harvesting machinery, and to provide an automatic transmission dual-pump hydraulic system and a control method thereof.

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

[0006] An automatic transmission dual-pump hydraulic system is special in that it includes: a transmission working hydraulic system, a transmission service brake hydraulic system and an oil tank;

[0007] The transmission working hydraulic system comprises: a first oil inlet circuit, a first gear pump that sucks oil from the oil tank into the first oil inlet circuit, a first oil filter, a main pressure regulating relief valve and an oil cooler that are connected in series in sequence to the first oil inlet circuit after the first gear pump, and an oil return circuit that is connected to the oil tank;

[0008] It also includes a safety valve whose oil inlet is connected to the first oil inlet oil circuit between the first gear pump and the first oil filter, and whose oil outlet is connected to the oil return oil circuit;

[0009] It also includes a plurality of clutch actuating units and a parking brake actuating unit arranged between the first oil inlet oil circuit and the oil return oil circuit in front of the main pressure regulating relief valve; the parking brake actuating unit includes a control valve, a cut-off valve, a parking brake piston connected in sequence, and a parking pressure sensor arranged on the oil circuit between the cut-off valve and the parking brake piston; the plurality of clutch actuating units include a low gear clutch actuating unit D1, a high gear clutch actuating unit D2, and a differential clutch actuating unit D3;

[0010] The transmission service brake hydraulic system comprises: a second oil inlet circuit, a second gear pump that sucks oil from the oil return circuit or the oil tank into the second oil inlet circuit, a second oil filter and a one-way valve connected in series in sequence to the second oil inlet circuit, and a service brake valve group installed between the second oil inlet circuit and the oil return circuit after the one-way valve; the service brake valve group comprises a left brake valve and a right brake valve respectively connected between the second oil inlet circuit and the oil return circuit after the one-way valve, wherein the oil outlet of the left brake valve is connected to a left brake piston, and the oil outlet of the right brake valve is connected to a right brake piston;

[0011] It also includes an overflow valve connected to the oil inlet and the second oil inlet circuit between the second oil filter and the one-way valve, the oil outlet of the overflow valve is connected to an auxiliary pressure regulating valve, the oil discharge port of the auxiliary pressure regulating valve is connected to the oil return circuit, and the oil outlet is connected to the second oil inlet circuit between the one-way valve and the accumulator.

[0012] Furthermore, the low gear clutch actuating unit D1, the high gear clutch actuating unit D2, and the differential clutch actuating unit D3 have the same structure, and each includes a combined solenoid valve and a piston;

[0013] The combined solenoid valve is an integrated cartridge valve, which is internally connected through an oil channel, and includes a solenoid valve control slide valve, a solenoid valve main valve, a throttle, an oil inlet, an oil outlet and an oil outlet, wherein the oil inlet is connected to the first oil inlet oil circuit, the oil outlet is connected to the oil return oil circuit, and the oil outlet is connected to the oil inlet of the piston;

[0014] When the combined solenoid valve is powered off, the solenoid valve controls the slide valve to be in the on state, the solenoid valve main valve is in the closed state, the pressure oil enters from the oil inlet, and after being throttled by the throttle, it flows back to the oil return line from the oil outlet through the solenoid valve control slide valve, and the piston is pressure-free; when the combined solenoid valve is powered on, the solenoid valve controls the slide valve to be in the off state, the solenoid valve main valve is turned on under the action of liquid pressure, the pressure oil enters the piston through the oil outlet, and the piston moves.

[0015] Furthermore, an accumulator, a temperature sensor, and a pressure sensor are sequentially installed on the first oil inlet oil line between the first oil filter and the main pressure regulating relief valve;

[0016] An accumulator is arranged on the second oil inlet oil circuit between the one-way valve and the service brake valve group.

[0017] Furthermore, the first oil filter and the second oil filter have a bypass function.

[0018] Furthermore, the opening pressure of the safety valve is 35 bar.

[0019] Furthermore, the first gear pump provides pressure oil with an oil pressure greater than 30 bar and a flow rate greater than 30 L / min; the second gear pump provides pressure oil with an oil pressure greater than 70 bar and a flow rate greater than 16 L / min.

[0020] Furthermore, the left brake valve and the right brake valve are three-position four-way sliding valves.

[0021] Furthermore, the oil discharge port of the overflow valve is connected to the oil return circuit.

[0022] At the same time, the present invention also provides a control method for the automatic transmission dual-pump hydraulic system, which is special in that it includes the following steps:

[0023] S1, the vehicle is powered on and ready to start, the control valve is energized, its oil circuit is connected, and the pressure oil pushes the piston to overcome the spring force of the parking brake and move, releasing the parking brake lock;

[0024] S2, the combined solenoid valve in the low gear clutch actuator D1 is energized and in the on position, the piston of the low gear clutch actuator D1 is filled with oil, the low gear clutch is engaged, the transmission is in the first gear, and the vehicle is driven in the first gear; the first gear is the low gear position of the transmission;

[0025] S3, judging whether the gear shifting condition is met according to the vehicle usage;

[0026] If yes, execute step 4; if no, execute S5;

[0027] S4, transmission shift;

[0028] S4.1, the combined solenoid valve of the low-gear clutch actuator D1 is powered off, and the combined solenoid valve of the high-gear clutch actuator D2 is powered on, so that the vehicle moves in the second gear;

[0029] S4.2, determine whether there is a vehicle stuck signal; if yes, execute S4.3; if not, execute S4.5;

[0030] S4.3, the combined solenoid valve of the high-gear clutch actuator D2 is powered off, the combined solenoid valve of the low-gear clutch actuator D1 is powered on, and the transmission is downgraded to 1st gear;

[0031] S4.4, the combined solenoid valve of the differential clutch actuator D3 is energized, the differential clutch is engaged, the half shafts on both sides move at the same speed, and the vehicle is freed. After the vehicle is freed, the combined solenoid valve of the differential clutch actuator D3 is de-energized, and then the process returns to S2;

[0032] S4.5, the transmission keeps the second gear, so that the vehicle moves in the second gear. When it is necessary to stop, the combined solenoid valve of the high-gear clutch actuator D2 is de-energized, the transmission is in the neutral position, and then S6 is executed;

[0033] S5, the transmission is kept in the first gear, the vehicle is driven in the first gear, and it is immediately determined whether there is a vehicle stuck signal; if yes, S6 is executed; if no, S7 is executed;

[0034] S6, the combined solenoid valve of the differential clutch execution unit D3 is energized, the differential clutch is engaged, the half shafts on both sides move at the same speed, and the vehicle is freed. After the vehicle is freed, the combined solenoid valve of the differential clutch execution unit D3 is de-energized, and then S7 is executed;

[0035] S7, the vehicle continues to move in the first gear until it needs to stop, the combined solenoid valve of the low gear clutch actuator D1 is de-energized, the transmission is in neutral, and then S8 is executed;

[0036] S8, cuts off the power to the control valve, disconnects its oil circuit, resets the piston, locks the parking brake, and completes the control of the automatic transmission dual-pump hydraulic system.

[0037] Beneficial effects of the present invention:

[0038] 1) The dual-pump hydraulic system of an automatic transmission of the present invention adopts a dual-pump design to provide different pressure oils for the transmission working system and the service brake system, which have different and greatly different oil pressure values ​​and flow rates. The pressure oil flow and oil pressure provided do not fluctuate greatly, thereby ensuring that the working conditions of the two systems are stable and reliable.

[0039] 2) In the transmission hydraulic system, an assembled solenoid valve with pilot proportional control is used. A small slide valve controlled by current is used to drive the working slide valve to charge and discharge the piston. A small current is used to control the small valve core. The hydraulic oil's own pressure is used to enter the working valve core drive chamber, and then the small valve core is used to control the working valve, which can amplify the execution ability of the small current.

[0040] 3) The automatic transmission dual-pump hydraulic system of the present invention adopts a combination of a cut-off valve and a proportional solenoid valve in the transmission working system to ensure the safety and normal operation of the transmission parking brake system.

[0041] 4) The dual-pump hydraulic system of an automatic transmission of the present invention adopts a differential control valve. When receiving a signal that the vehicle is stuck, the transmission can open the differential control valve to lock the wheels on both sides to help the vehicle get out of trouble.

[0042] 5) In the service brake system, a three-position four-way proportional solenoid valve that is linearly related to the pedal depth is used to control the connection and unloading of the service brake oil circuit, so that the oil pressure is proportional to the brake friction torque, and the braking force torque is indirectly linearly controlled, that is, the braking force is linearly controlled according to the driver's intention, allowing the vehicle to slow down and stop, and the braking process is gentle.

[0043] 6) The dual pumps working in the dual-pump hydraulic system of an automatic transmission of the present invention share an oil pool at the bottom of the transmission housing, saving housing space; the oil in the oil pool is circulated and replenished through multiple return oil circuits, which can meet the oil suction capacity of the dual pumps and prevent the oil pumps from being sucked empty. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 It is a structural schematic diagram of an embodiment of a dual-pump hydraulic system of an automatic transmission of the present invention;

[0045] Figure 2 It is a structural schematic diagram of a combined solenoid valve in an embodiment of an automatic transmission dual-pump hydraulic system of the present invention;

[0046] Figure 3 It is a schematic diagram of the shifting logic of a control method of an automatic transmission dual-pump hydraulic system of the present invention;

[0047] Figure 4 The present invention is a schematic diagram of the on-off state of each control valve in different gear positions according to a control method of an automatic transmission dual-pump hydraulic system.

[0048] Figure Number:

[0049] 1- Transmission working hydraulic system, 2- Transmission service brake hydraulic system, 3- Oil tank, 4- First gear pump, 5- First oil inlet circuit, 6- Safety valve, 7- First oil filter, 8- Accumulator, 9- Temperature sensor, 10- Pressure sensor, 11- Main pressure regulating overflow valve, 12- Combination solenoid valve, 13- Control valve, 14- Cut-off valve, 15- Parking pressure sensor, 16- Parking brake piston, 17- Piston, 18- Oil cooler, 19- Oil return circuit, 20- Second gear pump, 21- Second Oil inlet circuit, 22-second oil filter, 23-overflow valve, 24-auxiliary pressure regulating valve, 25-check valve, 26-accumulator, 27-service brake valve group, 28-left brake valve, 29-right brake valve, 30-right brake piston, 31-left brake piston, 32-solenoid valve control slide valve, 33-solenoid valve main valve, 34-throttle, 35-oil inlet, 36-oil drain, 37-oil outlet, D1-low gear clutch actuator unit, D2-high gear clutch actuator unit, D3-differential clutch actuator unit. DETAILED DESCRIPTION

[0050] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0051] An automatic transmission dual-pump hydraulic system provided by an embodiment of the present invention is as follows: Figure 1 As shown, it includes a transmission working hydraulic system 1, a transmission service brake hydraulic system 2, and an oil tank 3;

[0052] The transmission working hydraulic system 1 includes an oil tank 3, a first gear pump 4, a first oil inlet circuit 5, a safety valve 6, a first oil filter 7, an accumulator 8, a temperature sensor 9, a pressure sensor 10, a main pressure regulating overflow valve 11, an oil cooler 18, an oil return circuit 19, a low gear clutch actuator D1, a high gear clutch actuator D2, a differential clutch actuator D3, and a parking brake actuator;

[0053] The first oil filter 7, the main pressure relief valve 11 and the oil cooler 18 are connected in series in sequence on the first oil inlet circuit 5 after the first gear pump 4; the oil inlet of the safety valve 6 is connected to the first oil inlet circuit 5 between the first gear pump 4 and the first oil filter 7, and the oil outlet is connected to the return oil circuit 19, and the opening pressure is 35Bar. When the first oil filter 7 is blocked by system impurities and the oil pressure of the oil circuit increases to 35Bar, the safety valve 6 opens, and the pressure oil flows back to the oil tank 3 through the safety valve 6 and the return oil circuit 19, protecting the first gear pump 4 from damage;

[0054] The accumulator 8, the temperature sensor 9, and the pressure sensor 10 are sequentially installed on the first oil inlet circuit 5 between the first oil filter 7 and the main pressure regulating relief valve 11. The accumulator 8 plays a role in stabilizing the pressure. When the oil circuit of the transmission working hydraulic system is opened, the system pressure is stabilized, and the flow rate of the oil circuit is compensated to prevent the system pressure fluctuation from causing temporary failure of other oil circuits working at the same time. The temperature sensor 9 and the pressure sensor 10 respectively detect the temperature and pressure of the pressure oil entering each clutch actuator unit and the parking brake actuator unit;

[0055] The oil inlet of the main pressure regulating relief valve 11 is connected to the first oil inlet circuit 5, the oil outlet is connected to the oil return circuit 19, and the oil outlet is connected to an oil cooler 18; when the pressure of the pressure oil is relatively high, the main pressure regulating relief valve 11 opens, the oil cooler 18 is connected to the first oil inlet circuit 5, the pressure oil enters from the oil inlet of the main pressure regulating relief valve 11, flows out to the oil cooler 18 through the oil outlet, and flows into the oil return circuit 19 after cooling.

[0056] Each clutch actuator unit and the parking brake actuator unit are installed on the first oil inlet oil circuit 5 between the pressure sensor 10 and the main pressure regulating relief valve 11; the first gear pump 4 sucks oil from the oil tank 3 to generate pressure oil with an oil pressure greater than 30 bar and a flow rate greater than 30 L / min. The pressure oil enters the first oil filter 7 through the first oil inlet oil circuit 5. The first oil filter 7 has a bypass function to prevent the working device from being unable to supply oil after the first oil filter 7 is blocked; the pressure oil flowing out of the first oil filter 7 flows to the main pressure regulating relief valve 11, the oil pressure is stabilized to 30 Bar, and then flows into each clutch actuator unit and the parking brake actuator unit;

[0057] The parking brake actuator unit includes a control valve 13, a cut-off valve 14, a parking pressure sensor 15, and a parking brake piston 16; the oil inlet of the control valve 13 is connected to the first oil inlet oil circuit 5, the oil outlet is connected to the oil inlet of the cut-off valve 14, and the oil discharge port is connected to the return oil circuit 19; the oil outlet of the cut-off valve 14 is connected to the oil inlet of the piston 16, and a parking pressure sensor 15 is installed on the oil circuit between the piston 16 and the cut-off valve 14; the cut-off valve 14 is also in an energized and conductive state after the control valve 13 is energized. When the system is suddenly powered off, the cut-off valve 14 is disconnected to prevent the pressure oil of the parking brake piston 16 from flowing back, ensuring that the parking brake is unlocked. The parking pressure sensor 15 monitors the oil circuit pressure of the parking brake actuator unit at all times. Once the oil pressure of the parking brake piston 16 fails to reach the preset value, the parking brake control valve 13 will be energized at this time to replenish the oil circuit pressure.

[0058] The low gear clutch actuating unit D1 , the high gear clutch actuating unit D2 , and the differential clutch actuating unit D3 have the same structure, and each of them has an assembled solenoid valve 12 and a piston 17 .

[0059] like Figure 2 As shown, the assembled solenoid valve 12 is an assembled solenoid valve using pilot proportional control: a small slide valve controlled by current drives a working slide valve to charge and discharge oil to the piston, including a solenoid valve control slide valve 32, a solenoid valve main valve 33, a throttle 34, an oil inlet 35, an oil outlet 36 and an oil outlet 37, wherein the oil inlet 35 is connected to the first oil inlet oil circuit 5, the oil outlet 36 is connected to the oil return oil circuit 19, and the oil outlet 37 is connected to the oil inlet of the piston 17;

[0060] When the assembled solenoid valve 12 is powered off, the solenoid valve controls the slide valve 32 to be in position A, and the pressure oil enters from the oil inlet 35, and after being throttled by the throttle 34, it flows back to the return oil circuit 19 from the oil outlet 36 through the control valve position A. Since the oil circuit is unobstructed, there is no pressure at point a. At this time, the solenoid valve main valve 33 is in position C, and the oil outlet 37 between the pressure oil and the piston is closed, and the piston has no pressure; when the assembled solenoid valve 12 is powered on, the solenoid valve controls the slide valve 32 to be in position B under the action of electromagnetic force, and the pressure oil is disconnected. The pressure at point a is the oil pressure, and the solenoid valve main valve 33 is in position D under the action of the liquid pressure. The solenoid valve main valve 33 is turned on, and the pressure oil enters the piston through the oil outlet 37, and the piston moves.

[0061] The transmission service brake hydraulic system 2 comprises a second gear pump 20, a second oil inlet circuit 21, a relief valve 23, an auxiliary pressure regulating valve 24, a second oil filter 22, a one-way valve 25, a service brake valve group 27 connected in series on the second oil inlet circuit 21, and an accumulator 26 installed on the second oil inlet circuit 21 between the one-way valve 25 and the service brake valve group 27;

[0062] The one-way valve 25 is used to prevent the oil from flowing back due to inertia after the service brake valve group 27 is closed; the accumulator 26 is used to prevent the oil circuit pressure drop and insufficient pressure oil flow after the service brake valve group 28 is opened;

[0063] The oil inlet of the relief valve 23 is connected to the second oil inlet oil circuit 21 between the second oil filter 22 and the one-way valve 25, the oil outlet is connected to the oil inlet of the auxiliary pressure regulating valve 24, and the oil discharge port is connected to the oil return oil circuit 19; the oil outlet of the auxiliary pressure regulating valve 24 is connected to the second oil inlet oil circuit 21 between the one-way valve 25 and the accumulator 26, and the oil discharge port is connected to the oil return oil circuit 19; because the service brake valve group 27 is in a normally closed state, the oil discharge port of the relief valve 23 will always have a large flow and a certain pressure, so the oil discharge port of the relief valve 23 is connected to the oil return oil circuit 19, so that the oil circuit flow can be supplemented, which is beneficial to the first gear pump 4 and the second gear pump 20 to absorb oil and avoid empty suction of the oil pump;

[0064] The second gear pump 20 sucks oil from the oil return line 19 or the oil tank 3 to generate pressure oil with an oil pressure greater than 70 bar and a flow rate greater than 16 L / min. The pressure oil enters the second oil filter 22 through the second oil inlet line 21. The second oil filter 23 has a bypass function to prevent the working device from being unable to supply oil after the second oil filter 22 is blocked; the pressure oil flowing out of the second oil filter 22 flows through the overflow valve 24, the oil pressure is stabilized to 70 Bar, and flows into the service brake valve group 27 through the accumulator 26;

[0065] The service brake valve group 27 includes a left brake valve 28 and a right brake valve 29. The left brake valve 28 and the right brake valve 29 adopt three-position four-way slide valves linearly related to the depth of the foot pedal; wherein the oil outlet of the left brake valve 28 is connected to a left brake piston 31, and the oil outlet of the right brake valve 30 is connected to a right brake piston 30; the oil inlets of the left brake valve 28 and the right brake valve 29 are connected to the second oil inlet oil circuit 21; the oil discharge ports of the left brake valve 28 and the right brake valve 29 are respectively connected to the oil return oil circuit 19 to ensure that the pressure in the oil return pipeline is standard atmospheric pressure or negative pressure, so that the left brake piston 31 and the right brake piston 30 can return quickly;

[0066] When the vehicle is in driving state, the left brake valve 28 and the right brake valve 29 are in a state of being connected to the return oil circuit 19, ensuring that the left brake piston 31 and the right brake piston 30 are in a resistance-free state, and the left brake piston 31 and the right brake piston 30 can automatically return to their positions; when service braking is required, the foot pedal is stepped on, the left brake valve 28 and the right brake valve 29 are energized and switched, and the left brake valve 28 and the right brake valve 29 overcome the spring force under the action of electromagnetic force and are in a position where the pressure oil is connected to the left brake piston 31 and the right brake piston 30, and the left brake piston 31 and the right brake piston 30 are filled with oil to meet the service braking requirements.

[0067] At the same time, the present invention also provides a control method based on the above automatic transmission dual pump hydraulic system, referring to Figure 3-Figure 4 , including the following steps:

[0068] S1, the vehicle is powered on and ready to start, the control valve 13 is energized, its oil circuit is connected, and the pressure oil pushes the piston 16 to overcome the spring force of the parking brake and move, releasing the parking brake lock;

[0069] S2, the combined solenoid valve 12 in the low gear clutch actuator D1 is energized and in the on position, the piston 17 of the low gear clutch actuator D1 is filled with oil, the low gear clutch is engaged, the transmission is in the first gear, and the vehicle is driven in the first gear; the first gear is the low gear position of the transmission;

[0070] S3, judging whether the gear shifting condition is met according to the vehicle usage;

[0071] If yes, execute step 4; if no, execute S5;

[0072] S4, transmission shift;

[0073] S4.1, the combined solenoid valve 12 of the low-gear clutch actuator D1 is powered off, and the combined solenoid valve 12 of the high-gear clutch actuator D2 is powered on, so that the vehicle moves in the second gear;

[0074] S4.2, determine whether there is a vehicle stuck signal; if yes, execute S4.3; if not, execute S4.5;

[0075] S4.3, the combined solenoid valve 12 of the high-speed clutch actuator D2 is powered off, the combined solenoid valve 12 of the low-speed clutch actuator D1 is powered on, and the transmission is downgraded to 1st gear;

[0076] S4.4, the combined solenoid valve 12 of the differential clutch actuator D3 is energized, the differential clutch is engaged, the half shafts on both sides move at the same speed, and the vehicle is freed. After the vehicle is freed, the combined solenoid valve 12 of the differential clutch actuator D3 is de-energized, and then the vehicle returns to S2;

[0077] S4.5, the transmission keeps the second gear, so that the vehicle moves in the second gear. When the vehicle needs to stop, the combined solenoid valve 12 of the high gear clutch actuator D2 is de-energized, the transmission is in the neutral position, and then S6 is executed;

[0078] S5, the transmission is kept in the first gear, the vehicle is driven in the first gear, and it is immediately determined whether there is a vehicle stuck signal; if yes, S6 is executed; if no, S7 is executed;

[0079] S6, the combined solenoid valve 12 of the differential clutch actuator D3 is energized, the differential clutch is engaged, the half shafts on both sides move at the same speed, and the vehicle is freed. After the vehicle is freed, the combined solenoid valve 12 of the differential clutch actuator D3 is de-energized, and then S7 is executed;

[0080] S7, the vehicle continues to move in the first gear until it needs to stop, the combined solenoid valve 12 of the low gear clutch actuator D1 is powered off, the transmission is in neutral, and then S8 is executed;

[0081] S8, the control valve 13 is powered off to disconnect its oil circuit, the piston 16 is reset, the parking brake is locked, and the control of the automatic transmission dual-pump hydraulic system is completed.

Claims

1. An automatic transmission dual-pump hydraulic system, characterized in that: include: A transmission working hydraulic system (1), a transmission service brake hydraulic system (2) and an oil tank (3); The transmission working hydraulic system (1) comprises: a first oil inlet circuit (5), a first gear pump (4) for sucking oil from an oil tank (3) into the first oil inlet circuit (5), a first oil filter (7), a main pressure regulating overflow valve (11) and an oil cooler (18) connected in series on the first oil inlet circuit (5) after the first gear pump (4), and an oil return circuit (19) connected to the oil tank (3); It also includes a safety valve (6) whose oil inlet is connected to a first oil inlet oil circuit (5) between a first gear pump (4) and a first oil filter (7), and whose oil outlet is connected to an oil return oil circuit (19); The invention also comprises a plurality of clutch actuating units and a parking brake actuating unit arranged between a first oil inlet circuit (5) and an oil return circuit (19) in front of a main pressure regulating relief valve (11); the parking brake actuating unit comprises a control valve (13), a cut-off valve (14), a parking brake piston (16) connected in sequence, and a parking pressure sensor (15) arranged on the oil circuit between the cut-off valve (14) and the parking brake piston (16); the plurality of clutch actuating units comprises a low gear clutch actuating unit D1, a high gear clutch actuating unit D2, and a differential clutch actuating unit D3; The transmission service brake hydraulic system (2) comprises: a second oil inlet circuit (21), a second gear pump (20) that sucks oil from the oil return circuit (19) or the oil tank (3) into the second oil inlet circuit (21), a second oil filter (22) and a one-way valve (25) connected in series on the second oil inlet circuit (21), and a service brake valve group (27) installed between the second oil inlet circuit (21) and the oil return circuit (19) after the one-way valve (25); the service brake valve group (27) comprises a left brake valve (28) and a right brake valve (29) respectively connected between the second oil inlet circuit (21) and the oil return circuit (19) after the one-way valve (25), wherein the oil outlet of the left brake valve (28) is connected to a left brake piston (31), and the oil outlet of the right brake valve (29) is connected to a right brake piston (30); It also includes a relief valve (23) whose oil inlet is connected to the second oil inlet oil circuit (21) between the second oil filter (22) and the one-way valve (25); the oil outlet of the relief valve (23) is connected to an auxiliary pressure regulating valve (24); the oil discharge port of the auxiliary pressure regulating valve (24) is connected to the oil return oil circuit (19); and the oil outlet is connected to the second oil inlet oil circuit (21) between the one-way valve (25) and the accumulator (26).

2. The automatic transmission dual-pump hydraulic system according to claim 1, characterized in that: The low gear clutch actuating unit D1, the high gear clutch actuating unit D2 and the differential clutch actuating unit D3 have the same structure and each comprises a combined solenoid valve (12) and a piston (17); The combined solenoid valve (12) is an integrated cartridge valve, which is internally connected via an oil channel and comprises a solenoid valve control slide valve (32), a solenoid valve main valve (33), a throttle (34), an oil inlet (35), an oil outlet (36) and an oil outlet (37), wherein the oil inlet (35) is connected to the first oil inlet oil circuit (5), the oil outlet (36) is connected to the oil return oil circuit (19), and the oil outlet (37) is connected to the oil inlet of the piston (17).

3. The automatic transmission dual-pump hydraulic system according to claim 1, characterized in that: An accumulator (8), a temperature sensor (9), and a pressure sensor (10) are sequentially installed on the first oil inlet circuit (5) between the first oil filter (7) and the main pressure regulating relief valve (11); An accumulator (26) is provided on the second oil inlet passage (21) between the one-way valve (25) and the service brake valve group (27).

4. The automatic transmission dual-pump hydraulic system according to claim 1, characterized in that: The first oil filter (7) and the second oil filter (22) have a bypass function.

5. The automatic transmission dual-pump hydraulic system according to claim 1, characterized in that: The opening pressure of the safety valve (6) is 35 bar.

6. The automatic transmission dual-pump hydraulic system according to claim 1, characterized in that: The first gear pump (4) provides pressure oil with an oil pressure greater than 30 bar and a flow rate greater than 30 L / min; the second gear pump (20) provides pressure oil with an oil pressure greater than 70 bar and a flow rate greater than 16 L / min.

7. The automatic transmission dual-pump hydraulic system according to claim 1, characterized in that: The left brake valve (28) and the right brake valve (29) are three-position four-way slide valves.

8. The automatic transmission dual-pump hydraulic system according to claim 1, characterized in that: The oil discharge port of the overflow valve (23) is connected to the oil return line (19).

9. A control method for an automatic transmission dual-pump hydraulic system according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1, the vehicle is powered on and ready to start, the control valve (13) is energized, its oil circuit is connected, and the pressure oil pushes the piston (16) to overcome the spring force of the parking brake and move, thereby releasing the parking brake lock; S2, the combined solenoid valve (12) in the low gear clutch actuator D1 is energized and in the on position, the piston (17) of the low gear clutch actuator D1 is filled with oil, the low gear clutch is engaged, the transmission is in the first gear, and the vehicle is driven in the first gear; the first gear is the low gear position of the transmission; S3, judging whether the gear shifting condition is met according to the vehicle usage; If yes, execute step 4; if no, execute S5; S4, transmission shift; S4.1, the combined solenoid valve (12) of the low gear clutch actuator D1 is powered off, and the combined solenoid valve (12) of the high gear clutch actuator D2 is powered on, so that the vehicle moves in the second gear; S4.2, determine whether there is a vehicle stuck signal; if yes, execute S4.3; if not, execute S4.5; S4.3, the combined solenoid valve (12) of the high-speed clutch actuator D2 is powered off, the combined solenoid valve (12) of the low-speed clutch actuator D1 is powered on, and the transmission is downgraded to the first gear; S4.4, the combined solenoid valve (12) of the differential clutch actuator unit D3 is energized, the differential clutch is engaged, the half shafts on both sides move at the same speed, and the vehicle is freed. After the vehicle is freed, the combined solenoid valve (12) of the differential clutch actuator unit D3 is de-energized, and then the process returns to S2; S4.5, the transmission maintains the second gear, so that the vehicle moves in the second gear. When it is necessary to stop, the combined solenoid valve (12) of the high gear clutch execution unit D2 is powered off, the transmission is in the neutral position, and then S6 is executed; S5, the transmission is kept in the first gear, the vehicle is driven in the first gear, and it is immediately determined whether there is a vehicle stuck signal; if yes, S6 is executed; if no, S7 is executed; S6, the combined solenoid valve (12) of the differential clutch execution unit D3 is energized, the differential clutch is engaged, the half shafts on both sides move at the same speed, and the vehicle is freed. After the vehicle is freed, the combined solenoid valve (12) of the differential clutch execution unit D3 is de-energized, and then S7 is executed; S7, the vehicle continues to move in the first gear until it needs to stop, the combined solenoid valve (12) of the low gear clutch execution unit D1 is powered off, the transmission is in the neutral position, and then S8 is executed; S8, the control valve (13) is powered off to disconnect its oil circuit, the piston (16) is reset, the parking brake is locked, and the control of the automatic transmission dual-pump hydraulic system is completed.

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