A tractor double pump combined flow split load sensing hydraulic system

Abstract

The invention discloses a tractor double-pump merging and diverting load sensing hydraulic system, comprising a first variable pump, a first single-piston cylinder, a first variable control valve, a second variable pump, a second single-piston cylinder, a second variable control valve, a first throttle valve, a relief valve, a two-position three-way hydraulic control valve, a hydraulic control three-way valve, a second throttle valve, a third throttle valve and a shuttle valve. The output oil pressure of the first variable pump is P1, and the output end EF of the first variable pump and the output end EF of the second variable pump are respectively connected to the input end PO of a lifting system. The tractor double-pump merging and diverting load sensing hydraulic system adopts a load feedback double-variable pump for oil supply, and the hydraulic control three-way valve controls the liquid flow direction of the second variable pump, so as to realize the double-pump merging and diverting operation and steering priority functions, so that the agricultural machinery does not lose direction during operation to ensure safety, and at the same time realizes the double-pump control steering and lifting hydraulic output functions, thereby improving work efficiency and being more economical and efficient.

Description

Technical Field

[0001] The invention relates to the technical field of hydraulic systems, in particular to a tractor double-pump flow combining and dividing load sensing hydraulic system. Background Art

[0002] The hydraulic steering and lifting of traditional tractors are supplied by two fixed-displacement hydraulic pumps respectively, one for the steering oil circuit and the other for the lifting oil circuit, to control the hydraulic outputs such as steering and lifting respectively. However, the two oil circuits cannot work in coordination with each other, and the two fixed-displacement pumps always output pressure and flow, resulting in large energy loss, low efficiency and poor economy. In addition, because fixed-displacement pumps are used for oil supply, vibration and impact are large, which is particularly unfavorable for precise tillage depth control through hydraulic lifting. Summary of the invention

[0003] The technical problem to be solved by the present invention is to overcome the existing defects and provide a double-pump merging and diverting load-sensing hydraulic system for tractors. The system adopts a load feedback dual-variable pump to supply oil, and a hydraulically controlled three-way valve to control the flow direction of the liquid, thereby realizing the double-pump merging and diverting operation and steering priority functions, so that the agricultural machinery will not lose direction during operation to ensure safety, and at the same time realize the double-pump control of steering and lifting hydraulic output functions, thereby improving work efficiency and being more economical and effective, while reducing vibration and impact, and being able to achieve precise tillage depth control, which can effectively solve the problems in the background technology.

[0004] To achieve the above-mentioned purpose, the present invention provides the following technical scheme: a tractor dual-pump merging and diverting load sensing hydraulic system, comprising a first variable pump, a first single-piston cylinder, a first variable control valve, a second variable pump, a second single-piston cylinder, a second variable control valve, a first throttle valve, a relief valve, a two-position three-way hydraulic control valve, a hydraulic control three-way valve, a second throttle valve, a third throttle valve and a shuttle valve, the output oil pressure of the first variable pump is P1, the output end of the first variable pump and the output end EF of the second variable pump are respectively connected to the input end PO of the lifting system, the output end of the first variable pump is provided with a first variable control valve, the variable mechanism of the first variable pump is connected to the piston of the first single-piston cylinder, the output end of the first variable control valve is connected to the output end of the second variable control valve, the output oil pressure of the second variable pump is P2, the output end of the second variable pump is provided with a second variable control valve, the variable mechanism of the second variable pump is connected to the first The pistons of the two single-piston cylinders are connected, the output end of the second variable control valve is connected to the piston chamber of the second single-piston cylinder, the output end EF of the second variable pump is connected to the input end of the hydraulically controlled three-way valve, one way of the hydraulic oil output end of the hydraulically controlled three-way valve is connected to the input end PO of the lifting system, and the other way is respectively connected to the input end of the steering system CF and the input end of the second throttle valve, a third throttle valve is arranged between the hydraulically controlled three-way valve and the input end of the steering system CF, one output end of the second throttle valve is connected to the input end of the second variable control valve through a shuttle valve, the other output end of the second throttle valve is connected to the input end of the two-position three-way hydraulically controlled valve, the output port of the second throttle valve is the steering load feedback pressure Ls2, the oil inlet of the shuttle valve is connected to the external multi-way valve and the connection between the two is the multi-way valve load feedback pressure Ls1, one output end of the two-position three-way hydraulically controlled valve is connected to the input end of the overflow valve, and the other end is connected to the oil tank through the first throttle valve.

[0005] As a preferred technical solution of the present invention, the output end of the hydraulically controlled three-way valve is connected to the input end of the steering system CF through a first one-way valve, and the first one-way valve is located between the third throttle valve and the input end of the steering system CF.

[0006] As a preferred technical solution of the present invention, the hydraulic oil output end of the hydraulically controlled three-way valve is connected to the lifting system input end P0 through a second one-way valve.

[0007] As a preferred technical solution of the present invention, the hydraulically controlled three-way valve, the third throttle valve and the overflow valve constitute a priority valve system.

[0008] As a preferred technical solution of the present invention, the second throttle valve and the shuttle valve constitute a second variable pump displacement control oil circuit.

[0009] As a preferred technical solution of the present invention, both the first single-piston cylinder and the second single-piston cylinder are piston cylinders with spring return.

[0010] As a preferred technical solution of the present invention, the external multi-way valve oil return is connected to the oil tank.

[0011] Compared with the prior art, the beneficial effects of the present invention are as follows: the dual-pump merging and diverting load-sensing hydraulic system of the tractor is reasonably designed, novel in conception, and occupies little space when in use. The dual-pump control of the hydraulic output of steering and lifting is adopted to realize on-demand oil and pressure supply. The flow direction of the liquid in the second variable pump is controlled by setting a hydraulically controlled three-way valve to realize the functions of dual-pump merging and diverting and steering priority, so that the agricultural machinery does not lose direction during operation and the safety of the driving process is ensured. The shuttle valve 14 is set to control the displacement of the second variable pump with its maximum control pressure signal to realize automatic control of the output of the variable pump. By adopting a two-position three-way hydraulically controlled valve, the reaction speed during steering is fast to ensure steering safety; and the pressure relief at the end of steering flows to the oil tank through the first throttle valve, so that the steering stops slowly, smoothly and stably and ensures accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is the oil circuit control diagram of the present invention.

[0013] In the figure: 1 first variable pump, 2 first single piston cylinder, 3 first variable control valve, 4 second variable pump, 5 second single piston cylinder, 6 second variable control valve, 7 first throttle valve, 8 relief valve, 9 two-position three-way hydraulic control valve, 10 hydraulic control three-way valve, 11 first check valve, 12 second throttle valve, 13 second check valve, 14 shuttle valve, 15 third throttle valve. DETAILED DESCRIPTION

[0014] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not 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.

[0015] See also Figure 1The present invention provides a technical solution: a tractor double-pump confluence and diversion load sensing hydraulic system, comprising a first variable pump 1, a first single-piston cylinder 2, a first variable control valve 3, a second variable pump, a second single-piston cylinder 5, a second variable control valve 6, a first throttle valve 7, a relief valve 8, a two-position three-way hydraulic control valve 9, a hydraulic control three-way valve 10, a second throttle valve 12, a third throttle valve 15 and a shuttle valve 14, the output oil pressure of the first variable pump 1 is P1, the output end of the first variable pump 1 and the output end EF of the second variable pump 4 are respectively connected to the input end PO of the lifting system, the output end of the first variable pump 1 is provided with a first variable control valve 3, the variable mechanism of the first variable pump 1 is connected to the piston of the first single-piston cylinder 2, the first variable The output end of the quantity control valve 3 is connected to the output end of the second variable control valve 6, the output oil pressure of the second variable pump 4 is P2, the output end of the second variable pump 4 is provided with a second variable control valve 6, the variable mechanism of the second variable pump 4 is connected to the piston of the second single-piston cylinder 5, the output end of the second variable control valve 6 is connected to the piston chamber of the second single-piston cylinder 5, the first single-piston cylinder 2 and the second single-piston cylinder 5 are piston cylinders with spring return, the output end EF of the second variable pump 4 is connected to the input end of the hydraulically controlled three-way valve 10, the hydraulic oil output end of the hydraulically controlled three-way valve 10 is connected to the input end PO of the lifting system in one way, and the other way is respectively connected to the input end CF of the steering system and the input end of the second throttle valve 12, the hydraulically controlled three-way valve 10 is connected to the steering system A third throttle valve 15 is provided between the input ends of the system CF, one end of the output of the second throttle valve 12 is connected to the input end of the second variable control valve 6 through the shuttle valve 14, the other end of the output of the second throttle valve 12 is connected to the input end of the two-position three-way hydraulic control valve 9, the output port of the second throttle valve 12 is the steering load feedback pressure Ls2, the oil inlet of the shuttle valve 14 is connected to the external multi-way valve and the multi-way valve load feedback pressure Ls1 is at the connection point, the external multi-way valve return oil is connected to the oil tank, the larger value of the steering load feedback pressure Ls2 and the multi-way valve load feedback pressure Ls1 is Ls, which is convenient for controlling the displacement of the second variable pump 4 and realizing oil supply on demand, one end of the output end of the two-position three-way hydraulic control valve 9 is connected to the input end of the overflow valve 8, and the other end One end is connected to the oil tank through the first throttle valve 7, and the overflow valve 8 acts as a safety valve to limit the maximum steering pressure. The hydraulically controlled three-way valve 10, the third throttle valve 15 and the overflow valve 8 form a priority valve system. The priority valve controls the two-position three-way hydraulically controlled valve 9. The loading is fast and the response is rapid during steering, and the pressure relief at the end of steering flows to the oil tank through the first throttle valve 7. The steering stops slowly, smoothly and stably. The priority valve system ensures that the direction control is not lost during steering, ensuring driving safety. When there is no steering or the flow is sufficient, the fluid is supplied to the working device to speed up the operation and improve the operation efficiency. The double-pump combined-divider load-sensing hydraulic system of this tractor is reasonably designed and novel in conception. It occupies little space when in use and adopts double pumps to control the hydraulic output of steering and lifting.

[0016] When neither the steering nor the lifting hydraulic output is working, there is zero flow and zero power consumption: when neither the steering nor the lifting hydraulic output is working, the CF input end of the steering system and the EF outlet end of the second variable pump 4 are blocked, and no flow output is required. Under the action of the second variable pump 4, the pressure oil enters the hydraulic three-way valve 10 from the P2 port. Since the CF input end of the steering system is blocked, the pressure oil flows to the third throttle valve 15, overcomes the spring force of the hydraulic three-way valve 10, and pushes the valve core to the right. The control oil on the right side flows back to the oil tank from the right side through the two-position three-way hydraulic control valve 9 and then through the first throttle valve 7; since the steering and lifting hydraulic outputs are not working, the pressures of Ls1 and Ls2 are both zero. After the hydraulic oil flows through the shuttle valve 14, the control pressure output from Ls is used as It is used at the right end of the second variable control valve 6, and the pressure is zero. The output pressure of the second variable pump 4 acts on the left end of the second variable control valve 6 to overcome the spring pressure and push it to the left position to work. The output pressure P2 of the second variable pump 4 reaches the second single-piston cylinder 5 through the second variable control valve 6, and the pressure oil pushes the piston to zero displacement, and there is no flow output. At this time, although the second variable pump 4 is working, its power consumption is zero, that is, the power consumption is zero when there is no steering and no hydraulic output; among them, the hydraulically controlled three-way valve 10 works in the left position, and the thrust generated by the pressure at its output port is balanced with the spring force, the spring stiffness is low, and the pressure loss is small. Similarly, when the hydraulic output multi-way valve does not act, the oil outlet P1 is blocked, the pressure of Ls1 through the oil tank is zero, and the displacement of the first variable pump 1 is also zero.

[0017] Steering and lifting hydraulic output work, steering priority: when the lifting hydraulic output works but the steering does not work, the valve core of the hydraulically controlled three-way valve 10 is subjected to the hydraulic thrust on the left side of the hydraulically controlled three-way valve 10 by the control oil of the third throttle valve 15 under the P2 oil pressure, and at the same time is subjected to the combined force generated by the right spring force and the control oil thrust, and the control oil flows to the oil tank through the two-position three-way hydraulically controlled valve 9 and the first throttle valve 7; under the action of the thrust of the left pressure oil P2, the hydraulically controlled three-way valve 10 overcomes the right spring force, pushes the valve core to the right, and moves to the hydraulic output The multi-way valve supplies oil. At this time, the control oil circuit Ls outputs the pressure of Ls1 after comparison by the shuttle valve 14, and then transmits it to the second variable control valve 6. The second variable control valve 6 reaches a balance under the thrust generated by the sum of the Ls oil pressure thrust and the spring force on this side and the pressure of the P2 port. If the pressure at the P2 port increases, it means that the oil supply is too much. The valve core of the second variable control valve 6 moves to the right, and the pressure oil at the P2 port enters the second single-piston cylinder 5, pushing it to the left, reducing the displacement of the second variable pump 4, and realizing oil supply on demand; at the same time, Ls1 transmits The oil pressure at the P1 port is increased, indicating that the oil supply is too much. The valve core of the first variable control valve 3 moves to the right, and the pressure oil at the P1 port enters the first single-piston cylinder 2, pushing it to the left, reducing the displacement of the first variable pump 1, and realizing oil supply on demand. Vice versa, the two variable pumps can jointly supply oil to the working multi-way valve, speeding up the working speed and improving the efficiency. When there is a steering demand, the two-position three-way hydraulic control valve 9 is controlled by the The oil pressure of the upper Ls2 and the spring force on its west push the valve core downward under the action of the Ls2 oil pressure, so that it works from the upper position; the hydraulic three-way valve 10 pushes the valve core to the left under the combined action of the hydraulic thrust on the left, the spring force on the right and the thrust of the control oil Ls2, and supplies oil to the input end of the steering system CF to ensure steering priority. The high-pressure oil transmitted by the control oil circuit Ls controls the output oil volume of the second variable pump 4. At this time, the lifting oil circuit is supplied with oil by the first variable pump 1, so that separate oil supplies are realized without affecting each other.

[0018] The present invention can be conveniently operated, occupies little space when in use, and is easy to operate and use; a double pump can be used to control the hydraulic output of steering and lifting, thereby improving convenience of use; the setting of the overflow valve 8 acts as a safety valve for limiting the maximum steering pressure, thereby further improving convenience of use.

[0019] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A tractor dual-pump combined-divider load sensing hydraulic system, characterized in that: The invention comprises a first variable pump (1), a first single-piston cylinder (2), a first variable control valve (3), a second variable pump (4), a second single-piston cylinder (5), a second variable control valve (6), a first throttle valve (7), a relief valve (8), a two-position three-way hydraulic control valve (9), a hydraulic control three-way valve (10), a second throttle valve (12), a third throttle valve (15) and a shuttle valve (14); the output oil pressure of the first variable pump (1) is P1; the output end of the first variable pump (1) and the output end EF of the second variable pump (4) are respectively connected to the input end PO of the lifting system; the output end of the first variable pump (1) is provided with a first variable control valve (3); the variable mechanism of the first variable pump (1) is connected to the piston of the first single-piston cylinder (2); the output end of the first variable control valve (3) is connected to the output end of the second variable control valve (6); The output oil pressure of the second variable pump (4) is P2. The output end of the second variable pump (4) is provided with a second variable control valve (6). The variable mechanism of the second variable pump (4) is connected to the piston of the second single-piston cylinder (5). The output end of the second variable control valve (6) is connected to the piston chamber of the second single-piston cylinder (5). The output end EF of the second variable pump (4) is connected to the input end of the hydraulically controlled three-way valve (10). One path of the hydraulic oil output end of the hydraulically controlled three-way valve (10) is connected to the input end PO of the lifting system, and the other path is respectively connected to the input end CF of the steering system and the input end of the second throttle valve (12). The hydraulically controlled three-way valve (10) is connected to A third throttle valve (15) is provided between the input ends of the steering system CF, one output end of the second throttle valve (12) is connected to the input end of the second variable control valve (6) through a shuttle valve (14), the other output end of the second throttle valve (12) is connected to the input end of the two-position three-way hydraulic control valve (9), the output port of the second throttle valve (12) is a steering load feedback pressure Ls2, the oil inlet of the shuttle valve (14) is connected to an external multi-way valve and the multi-way valve load feedback pressure Ls1 is at the connection between the two, one output end of the two-position three-way hydraulic control valve (9) is connected to the input end of the overflow valve (8), and the other end is connected to the oil tank through the first throttle valve (7); The output end of the hydraulically controlled three-way valve (10) is connected to the input end of the steering system CF via a first one-way valve (11), and the first one-way valve (11) is located between the third throttle valve (15) and the input end of the steering system CF; The hydraulic oil output end of the hydraulically controlled three-way valve (10) is connected to the lifting system input end P0 via a second one-way valve (13).

2. A tractor dual-pump combined-divider load sensing hydraulic system according to claim 1, characterized in that: The hydraulically controlled three-way valve (10), the third throttle valve (15) and the overflow valve (8) form a priority valve system.

3. A tractor dual-pump combined-divider load sensing hydraulic system according to claim 1, characterized in that: The second throttle valve (12) and the shuttle valve (14) form a displacement control oil circuit for the second variable displacement pump (4).

4. A tractor dual-pump combined-divider load sensing hydraulic system according to claim 1, characterized in that: The first single-piston cylinder (2) and the second single-piston cylinder (5) are both piston cylinders with self-contained spring return.

5. A tractor dual-pump combined-divider load sensing hydraulic system according to claim 1, characterized in that: The external multi-way valve oil return is connected to the oil tank.

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