High-horsepower tractor flow sharing hydraulic system

Abstract

The invention relates to the technical field of tractor hydraulic control systems, in particular to a high-horsepower tractor flow sharing hydraulic system. The hydraulic control system comprises a variable pump and a proportional multi-way valve used for controlling hydraulic output, a head link, a lifting link, a tail link and a plurality of machine tool using links are arranged in the proportional multi-way valve, an oil way on the lifting link is connected to a tractor lifting oil cylinder, and oil ways on the machine tool using links are connected to a machine tool motor and a machine tool oil cylinder respectively; a tractor lifting oil cylinder control unit is arranged in the lifting unit, and a machine tool motor control unit and a machine tool oil cylinder control unit are arranged in the machine tool using unit. According to the multi-way valve, the tractor lifting oil cylinder and the machine tool hydraulic actuator share the flow of the variable pump in proportion, and when the flow of the variable pump cannot meet the requirements of the multiple actuators, the hydraulic system can distribute the flow of the variable pump according to the opening degrees and proportions of valve elements of different control units in the multi-way valve, so that all the actuators act in a coordinated mode at the same time.

Description

Technical Field

[0001] The present invention relates to the technical field of tractor hydraulic control systems, and particularly relates to a flow-sharing hydraulic system for large-horsepower tractors. Background Art

[0002] In heavy equipment such as agricultural machinery and construction machinery, the hydraulic system is the core part for power transmission and precise control. Traditional hydraulic systems usually adopt control methods of fixed-displacement pumps + throttle valves or ordinary multi-way valves, which have certain defects. For example, the fixed-displacement pump always supplies oil at the maximum displacement, while the required flow rate of the actuator changes with the working conditions, and the excess flow is wasted through the relief valve or throttle valve, resulting in serious system heating and a large amount of energy consumption; ordinary multi-way valves lack pressure compensation functions. When multiple actuators act simultaneously, the circuit with a lower load pressure will obtain the flow rate first, while the actuator with a higher load will be slow or stagnant due to insufficient flow rate, affecting the operation accuracy; traditional electromagnetic directional valves can only achieve on-off control and cannot steplessly adjust the speed and force of the actuator, making it difficult to meet the requirements of modern agricultural machinery for fine operations. Summary of the Invention

[0003] The purpose of the present invention is to provide a rationally designed flow-sharing hydraulic system for large-horsepower tractors to solve the above-mentioned defects in view of the deficiencies and drawbacks of the prior art.

[0004] To achieve the above purpose, the present invention adopts the following technical solutions: It includes a variable pump and a proportional multi-way valve connected thereto for controlling hydraulic output. The proportional multi-way valve is provided with a head connection, a lift connection, a tail connection, and multiple implement usage connections. The oil circuit on the lift connection is connected to the tractor lift cylinder, and the oil circuits on the implement usage connections are respectively connected to the implement motor and the implement cylinder; a tractor lift cylinder control connection is provided in the lift connection, and an implement motor control connection and an implement cylinder control connection are respectively provided in the implement usage connections. The inlet of the variable pump is connected to the fuel tank, and the outlet is connected to a high-pressure filter, and then connected to the head connection, the lift connection, the tail connection, and multiple implement usage connections through the main high-pressure oil circuit. A variable pump displacement control piston is also provided in the variable pump. A variable pump load-sensing valve and a variable pump pressure cut-off valve are installed on the variable pump. A load-sensing oil circuit (LS) is connected to the tractor lift cylinder control connection, the implement motor control connection, and the implement cylinder control connection in the proportional multi-way valve, and this oil circuit is connected to the variable pump load-sensing valve for load pressure feedback. The variable pump load-sensing valve is connected to one end of the variable pump displacement control piston through the variable pump pressure cut-off valve.

[0005] Preferably, a return oil circuit connected to the fuel tank is provided in the proportional multi-way valve, and a return oil filter is provided on the return oil circuit.

[0006] Preferably, both ends of the tractor lift cylinder control union, the implement motor control union, and the implement cylinder control union are respectively connected with a multi-way valve pilot control proportional pressure reducing valve I and a multi-way valve pilot control proportional pressure reducing valve II, and multiple multi-way valve pilot control proportional pressure reducing valve Is and multi-way valve pilot control proportional pressure reducing valve IIs are all connected in parallel.

[0007] Preferably, a pilot control pressure reducing valve is connected to the main high-pressure oil path inside the proportional multi-way valve. The pilot control pressure reducing valve is installed in the tail union, and the oil outlet of the pilot control pressure reducing valve is connected to the multi-way valve pilot control proportional pressure reducing valve I and the multi-way valve pilot control proportional pressure reducing valve II.

[0008] Preferably, a lift cylinder buffer valve I and a lift cylinder buffer valve II connected to the return oil path are respectively provided at two oil ports of the tractor lift cylinder.

[0009] Preferably, an LS oil path pressure limiting valve is connected between the return oil path and the load sensing oil path (LS).

[0010] Preferably, pressure compensation valves are provided between the tractor lift cylinder control union, the implement motor control union, the implement cylinder control union and the load sensing oil path (LS).

[0011] Preferably, a load holding valve is provided in the oil path connected to one end of the tractor lift cylinder in the lift union.

[0012] After adopting the above structure, the beneficial effects of the present invention are as follows: 1. In the present invention, the tractor lift cylinder and the implement hydraulic actuator proportionally share the flow rate of the variable pump. When the flow rate of the variable pump cannot meet the needs of multiple actuators, the hydraulic system can proportionally distribute the flow rate of the variable pump according to the spool opening degrees of different control unions in the multi-way valve, so that each actuator can act coordinately at the same time, solving the defect that only the light-load actuator can be preferentially satisfied.

[0013] 2. In the present invention, the variable pump adjusts the output flow rate as needed, and there is less energy waste.

[0014] 3. When the flow rate of the variable pump is sufficient in the present invention, for example, when only one hydraulic actuator acts, the flow rate ratio of the actuator (tractor lift cylinder or implement hydraulic actuator) can be adjusted, accurately meeting the action requirements of the tractor lift cylinder and the implement hydraulic actuator. At the same time, the variable pump supplies oil as needed, the hydraulic system is energy-saving, and the system pressure loss is small. Description of the Drawings

[0015] Figure 1 is the schematic diagram of the hydraulic system of the present invention; Figure 2 is the schematic diagram of the hydraulic principle when the tractor lift cylinder rises in the present invention; Figure 3It is a schematic diagram of the flow - sharing hydraulic principle of the present invention.

[0016] Description of the reference numerals in the drawings: 1. Variable pump; 2. High - pressure filter; 3. Proportional multi - way valve; 4. Return - oil filter; 5. Fuel tank; 6. Tractor lift cylinder; 7. Implement motor I; 8. Implement cylinder I; 9. Implement cylinder II; 10. Implement motor II; 101. Variable - pump load - sensing valve; 102. Variable - pump pressure - cut - off valve; 103. Variable - pump displacement control piston; 301. LS - circuit pressure - limiting valve; 302. Lift - cylinder buffer valve I; 303. Lift - cylinder buffer valve II; 304. Pressure - compensation valve; 305. Tractor lift - cylinder control union; 306. Implement - motor control union I; 307. Implement - cylinder control union I; 308. Implement - cylinder control union II; 309. Implement - motor control union II; 3010. Multi - way - valve pilot - control proportional pressure - reducing valve I; 3011. Multi - way - valve pilot - control proportional pressure - reducing valve II; 3012. Load - holding valve; 3013. Pilot - control pressure - reducing valve; A. Head union; B. Lift union; C. Implement - use union; D. Tail union. Specific embodiments

[0017] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0018] Refer to Figure 1 As shown, it includes a variable pump 1 and a proportional multi - way valve 3 connected thereto for controlling hydraulic output. The proportional multi - way valve 3 is provided with a head union, a lift union, a tail union, and four implement - use unions. The oil circuit on the lift union is connected to the tractor lift cylinder 6. Among the four implement - use unions, there are respectively an implement - motor control union I 306, an implement - cylinder control union I 307, an implement - cylinder control union II 308, and an implement - motor control union II 309, and are respectively connected to an implement motor I 7, an implement cylinder I 8, an implement cylinder II 9, and an implement motor II 10; the lift union is provided with a tractor lift - cylinder control union 305; The inlet port of the variable pump 1 is connected to the fuel tank 5, and the outlet port is connected to the high-pressure filter 2, and then connected to the head connection, lift connection, tail connection, and multiple implement usage connections through the main high-pressure oil circuit. The variable pump 1 is also provided with a variable pump displacement control piston 103. A variable pump load-sensitive valve 101 and a variable pump pressure cut-off valve 102 are installed on the variable pump 1. The tractor lift cylinder control connection 305, the implement motor control connection 1 306, the implement cylinder control connection 1 307, the implement cylinder control connection 2 308, and the implement motor control connection 2 309 in the proportional multi-way valve 3 are connected to a load-sensitive oil circuit (LS), and this oil circuit is connected to the variable pump load-sensitive valve 101 for load pressure feedback. The variable pump load-sensitive valve 101 is connected to one end of the variable pump displacement control piston 103 through the variable pump pressure cut-off valve 102. When the system pressure is higher than the set value, the valve is opened, and the pressure is introduced into one end of the variable pump displacement control piston 103, forcing the swash plate of the variable pump 1 to rotate to a small displacement or 0 to achieve protection. A return oil circuit connected to the fuel tank 5 is provided in the proportional multi-way valve 3, and a return oil filter 4 is provided on the return oil circuit. An LS oil circuit pressure limiting valve 301 is connected between the return oil circuit and the load-sensitive oil circuit (LS). Both ends of the tractor lift cylinder control connection 305, the implement motor control connection 1 306, the implement cylinder control connection 1 307, the implement cylinder control connection 2 308, and the implement motor control connection 2 309 are connected with a multi-way valve pilot control proportional pressure reducing valve 1 3010 and a multi-way valve pilot control proportional pressure reducing valve 2 3011, and multiple multi-way valve pilot control proportional pressure reducing valves 1 3010 and multi-way valve pilot control proportional pressure reducing valves 2 3011 are in parallel; A pilot control pressure reducing valve 3013 is connected to the main high-pressure oil circuit inside the proportional multi-way valve 3. The pilot control pressure reducing valve 3013 is installed inside the tail connection. The outlet port of the pilot control pressure reducing valve 3013 is connected to the multi-way valve pilot control proportional pressure reducing valve 1 3010 and the multi-way valve pilot control proportional pressure reducing valve 2 3011. Pressure compensation valves 304 are provided between the tractor lift cylinder control connection 305, the implement motor control connection 1 306, the implement cylinder control connection 1 307, the implement cylinder control connection 2 308, and the implement motor control connection 2 309 and the load-sensitive oil circuit (LS). The pilot control pressure reducing valve 3013 ensures the pilot pressure for the commutation of each control connection; Therefore, the proportional multi-way valve 3 is controlled by the multi-way valve pilot control proportional pressure reducing valve 1 3010 and the multi-way valve pilot control proportional pressure reducing valve 2 3011. By changing the proportional valve core opening, with the cooperation of the pressure compensation valve 304, the proportional adjustment of the flow rate is achieved. When multiple actuators move synchronously and the flow rate is saturated, the flow rate of the variable pump 1 can be shared according to the valve port opening; On the two oil ports of the tractor lift cylinder 6, there are respectively provided a lift cylinder buffer valve one 302 and a lift cylinder buffer valve two 303 connected to the oil return circuit to absorb the oil pressure fluctuations caused by bumps, provide protection, and prevent cavitation; in the oil circuit connected to one end of the tractor lift cylinder 6 in the lift connection center, there is provided a load holding valve 3012 to maintain the lifted state of the implement without starting the equipment during transportation, ensure the ground clearance, and the static settlement meets the standard requirements.

[0019] Principle example of this embodiment during operation: As Figure 2 shown, the proportional reducing valve two 3011 of the pilot control of the multi-way valve below the tractor lift cylinder control union 305 receives an electrical signal, the tractor lift cylinder control union 305 is in the lower position, the standby pressure oil at the pump port passes through the tractor lift cylinder control union 305, then enters the LS oil circuit through the pressure compensation valve 304, and then is transmitted to the variable pump load sensing valve 101. After the variable pump 1 receives the pressure signal, it ends the standby state; the pump displacement changes from zero to the appropriate position according to the flow rate required by the multi-way valve, and the pump starts to supply oil. The pressure oil at the pump port sequentially passes through the tractor lift cylinder control union 305 and the pressure compensation valve 304, reaches the load holding valve 3012 (the pressure oil in the control chamber of this valve is unloaded through the control union and the valve core opens), and then enters the lower chamber of the tractor lift cylinder 6 to push the cylinder to rise; at the same time, the oil in the upper chamber of the tractor lift cylinder 6 passes through the lift cylinder control union and then returns to the fuel tank 5 through the oil return filter 4 to complete the predetermined action; the opening degree of the control union valve port determines the flow rate of the lift cylinder, and the pressure difference at both ends of the valve core opening of the tractor lift cylinder control union 305 is fed back to both ends of the valve core of the load sensing valve. The variable pump 1 adjusts the pump displacement according to the pressure difference at both ends of the valve core of the load sensing valve to supply oil as needed, achieving energy conservation and avoiding energy loss.

[0020] Principle example of sharing hydraulic pressure in this embodiment: As Figure 3As shown in the figure, taking the two actuators of the tractor lift cylinder 6 and the implement cylinder II 9 as examples for analysis; assuming that the load of the tractor lift cylinder 6 is small, its corresponding control spool opens first and the cylinder acts first; the load of the implement cylinder II 9 is large, and its corresponding control spool opens later and the implement cylinder acts later; during the process when the tractor lift cylinder 6 starts to act independently, the flow rate of the variable pump 1 meets the requirements of the cylinder; when the control spool corresponding to the implement cylinder II 9 opens, assuming that the flow rate of the variable pump 1 cannot meet the combined action requirements of the tractor lift cylinder 6 and the implement cylinder II 9 at the same time, at this time, the outlet pressure of the variable pump 1 passes through the tractor lift cylinder control union 305, the implement motor control union I 306, the implement cylinder control union I 307, and the implement cylinder control union II 308 in sequence, reaches the pressure compensation valve 304 on the implement cylinder II 9, and then acts on the lower end of the pressure compensation valve 304 on the tractor lift cylinder 6 to close it, and the system is blocked; when the pressure rises to a value that can drive the large load of the cylinder, the pressure compensation valve 304 of the tractor lift cylinder 6 opens again. At this time, the tractor lift cylinder 6 and the implement cylinder II 9 act simultaneously. The pressure loss at both ends of the pressure compensation valve 304 is the pressure of the implement cylinder II 9 minus the pressure of the tractor lift cylinder 6. The inlet pressure of the valve ports of the tractor lift cylinder control union 305 and the implement cylinder control union II 308 is the outlet pressure of the variable pump 1, and the outlet pressure of the valve ports is the pressure corresponding to the large load of the cylinder. The pressure losses of the two proportional throttle valve ports are the same, and the two share the flow rate of the variable pump 1 according to the valve port opening ratio.

[0021] It should be understood that the above specific embodiments of the present invention are only used for exemplary illustration or explanation of the principle of the present invention, and do not constitute a limitation to the present invention. Therefore, any modifications, equivalent replacements, improvements, etc. made without departing from the spirit and scope of the present invention shall be included within the protection scope of the present invention. In addition, the appended claims of the present invention are intended to cover all changes and modifications that fall within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

Claims

1. A flow sharing hydraulic system for a high-horsepower tractor, comprising a variable displacement pump (1), characterized in that: The variable pump (1) is connected to a proportional multi-way valve (3) for controlling hydraulic output. The proportional multi-way valve (3) is provided with a head connection, a lifting connection, a tail connection and a plurality of implement use connections. The oil circuit on the lifting connection is connected to the tractor lifting cylinder (6), and the oil circuit on the implement use connection is respectively connected to the implement motor and the implement cylinder; the lifting connection is provided with a tractor lifting cylinder control connection (305), and the implement use connection is respectively provided with an implement motor control connection and an implement cylinder control connection; The oil inlet of the variable pump (1) is connected to the oil tank (5), and the oil outlet is connected to the high-pressure filter (2), and then connected to the head link, the lifting link, the tail link and multiple machine tool use links through the main high-pressure oil circuit. The variable pump (1) is also provided with a variable pump displacement control piston (103). The variable pump (1) is equipped with a variable pump load sensing valve (101) and a variable pump pressure cut-off valve (102). The tractor lifting cylinder control link (305), the machine tool motor control link and the machine tool cylinder control link in the proportional multi-way valve (3) are connected to a load sensing oil circuit (LS). The oil circuit is connected to the variable pump load sensing valve (101) for load pressure feedback. The variable pump load sensing valve (101) is connected to one end of the variable pump displacement control piston (103) through the variable pump pressure cut-off valve (102). The tractor lifting cylinder control link (305), the implement motor control link, and a pressure compensation valve (304) are provided between the implement cylinder control link and the load sensitive oil circuit (LS); The proportional multi-way valve (3) is provided with an oil return path connected to the oil tank (5), and an oil return filter (4) is provided on the oil return path.

2. A high-horsepower tractor flow sharing hydraulic system according to claim 1, characterized in that: The two ends of the tractor lifting cylinder control link (305), the implement motor control link and the implement cylinder control link are respectively connected to a multi-way valve pilot-controlled proportional pressure reducing valve 1 (3010) and a multi-way valve pilot-controlled proportional pressure reducing valve 2 (3011), and the plurality of multi-way valve pilot-controlled proportional pressure reducing valves 1 (3010) and multi-way valve pilot-controlled proportional pressure reducing valves 2 (3011) are all connected in parallel.

3. A flow sharing hydraulic system for high-horsepower tractors according to claim 2, characterized in that: A pilot-controlled pressure reducing valve (3013) is connected to the main high-pressure oil circuit in the proportional multi-way valve (3). The pilot-controlled pressure reducing valve (3013) is installed in the tail connection. The oil outlet of the pilot-controlled pressure reducing valve (3013) is connected to the multi-way valve pilot-controlled proportional pressure reducing valve 1 (3010) and the multi-way valve pilot-controlled proportional pressure reducing valve 2 (3011).

4. A flow sharing hydraulic system for high-horsepower tractors according to claim 1, characterized in that: A first lifting cylinder buffer valve (302) and a second lifting cylinder buffer valve (303) connected to the oil return line are respectively provided on the two oil ports of the tractor lifting cylinder (6).

5. The flow sharing hydraulic system for high-horsepower tractors according to claim 1, characterized in that: An LS oil circuit pressure limiting valve (301) is connected between the oil return circuit and the load sensitive oil circuit (LS).

6. The flow sharing hydraulic system for high-horsepower tractors according to claim 1, characterized in that: A load holding valve (3012) is provided in the oil circuit in the lifting link connected to one end of the tractor lifting cylinder (6).

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