Micro-flow hydraulic transmission system and control method thereof

Abstract

The invention discloses a micro-flow hydraulic transmission system and a control method thereof. The micro-flow hydraulic transmission system comprises a first oil way, a second oil way, a first electromagnetic reversing valve, a second electromagnetic reversing valve, an oil cylinder and an oil tank. The first oil way is connected with the oil tank, and the oil outlet end of the first oil way communicates with a port P7 of the first electromagnetic reversing valve. The second oil way is connected with the oil tank, and the oil outlet end of the second oil way is communicated with a T5 port of the first electromagnetic reversing valve; an outlet A4 of the first electromagnetic directional valve is communicated with an inlet P8 of the second electromagnetic directional valve, an outlet B4 of the first electromagnetic directional valve and an oil return port T6 of the second electromagnetic directional valve are communicated with the oil tank, an outlet A5 of the second electromagnetic directional valve is communicated with an inlet A6 of the oil cylinder, and an outlet B5 of the second electromagnetic directional valve is communicated with an inlet B6 of the oil cylinder; a first hydraulic motor is arranged on the first oil way, a second hydraulic motor is arranged on the second oil way, and a rotor of the first hydraulic motor is connected with a rotor of the second hydraulic motor; the valve can achieve stable control over micro flow, and is simple in structure, resistant to high pressure and low in cost.

Description

Technical Field

[0001] The present invention relates to the field of hydraulic transmission technology, and in particular, to a micro-flow hydraulic transmission system. In addition, the present invention also relates to a control method including the micro-flow hydraulic transmission system. Background Art

[0002] With the continuous development of hydraulic technology, the control accuracy of hydraulic systems is increasingly required in some application scenarios or experimental tests such as machining equipment, robot control, and aerospace. The control of physical parameters such as displacement and speed by hydraulic systems is actually achieved by controlling the flow of the hydraulic system, and the control accuracy depends on the minimum flow that the hydraulic system can control. Therefore, the control of small flow determines the control accuracy of some high-precision hydraulic systems.

[0003] The existing micro-flow control method generally adopts the form of a quantitative pump + servo motor. This structure can achieve the control of a certain small flow rate. Since the quantitative pump has a minimum stable speed requirement, it cannot achieve stable control of micro-flows such as a speed of tens of r / min. Moreover, under high pressure, the volumetric efficiency is low, and the flow is more unstable at low speed. There is also a method of using magnetic sensitive materials to make throttle holes, and changing the throttle hole area by changing the magnetic field to achieve micro-flow control, such as Chinese patent CN 109718731B. The throttle hole material is complex, the control difficulty is high, and it is not resistant to high pressure, which is difficult to apply to the micro-flow control of hydraulic systems. Summary of the invention

[0004] The invention provides a micro-flow hydraulic transmission system and a control method thereof, so as to solve the technical problem that the existing micro-flow hydraulic transmission system is difficult to control micro-flow.

[0005] According to one aspect of the present invention, there is provided a micro-flow hydraulic transmission system, comprising a first oil circuit for providing a large-flow pressure oil, a second oil circuit for providing a small-flow pressure oil, a first electromagnetic reversing valve, a second electromagnetic reversing valve, an oil cylinder and an oil tank; the oil inlet end of the first oil circuit is connected to the oil tank, and the oil outlet end of the first oil circuit is connected to the P7 port of the first electromagnetic reversing valve; the oil inlet end of the second oil circuit is connected to the oil tank, and the oil outlet end of the second oil circuit is connected to the T5 port of the first electromagnetic reversing valve; the outlet A4 of the first electromagnetic reversing valve is connected to the inlet P8 of the second electromagnetic reversing valve, the outlet B4 of the first electromagnetic reversing valve and the oil return port T6 of the second electromagnetic reversing valve are connected to the oil tank, the outlet A5 of the second electromagnetic reversing valve is connected to the inlet A6 of the oil cylinder, and the outlet B5 of the second electromagnetic reversing valve is connected to the inlet B6 of the oil cylinder; a first hydraulic motor is arranged on the first oil circuit, a second hydraulic motor is arranged on the second oil circuit, and a rotor of the first hydraulic motor is connected to a rotor of the second hydraulic motor.

[0006] Furthermore, a large-flow pump and a proportional speed control valve are arranged on the first oil circuit, the oil suction port S1 of the large-flow pump is connected to the oil tank, the outlet P1 of the large-flow pump is connected to the inlet A1 of the proportional speed control valve, the outlet B1 of the proportional speed control valve is connected to the inlet A2 of the first hydraulic motor, and the outlet B2 of the first hydraulic motor is connected to the P7 port of the first electromagnetic reversing valve; a small-flow pump is also arranged on the second oil circuit, the oil suction port S2 of the small-flow pump is connected to the oil tank, the outlet P2 of the small-flow pump is connected to the inlet A3 of the second hydraulic motor, and the outlet B3 of the second hydraulic motor is connected to the T5 port of the first electromagnetic reversing valve; the displacement V1 of the first hydraulic motor is greater than the displacement V2 of the second hydraulic motor.

[0007] Furthermore, the rotor of the first hydraulic motor is connected to the rotor of the second hydraulic motor via a reducer.

[0008] Furthermore, a large flow pump and a proportional speed regulating valve are arranged on the first oil circuit, the oil suction port S1 of the large flow pump is connected to the oil tank, the outlet P1 of the large flow pump is connected to the inlet A1 of the proportional speed regulating valve, the outlet B1 of the proportional speed regulating valve is connected to the inlet A2 of the first hydraulic motor, and the outlet B2 of the first hydraulic motor is connected to the P7 port of the first electromagnetic reversing valve; a small flow pump is also arranged on the second oil circuit, the oil suction port S2 of the small flow pump is connected to the oil tank, the outlet P2 of the small flow pump is connected to the inlet A3 of the second hydraulic motor, and the outlet B3 of the second hydraulic motor is connected to the T5 port of the first electromagnetic reversing valve; the displacement V1 of the first hydraulic motor is equal to the displacement V2 of the second hydraulic motor, and the rotor of the first hydraulic motor is connected to the rotor of the second hydraulic motor through a reducer.

[0009] Furthermore, the pressure oil flow rate at the oil outlet end of the first oil circuit is V3, the pressure oil flow rate at the oil outlet end of the second oil circuit is V4, and the range of V3:V4 is 10:1 to 1000:1.

[0010] Furthermore, the first oil circuit also includes a first proportional relief valve, the outlet T1 of the first proportional relief valve is connected to the oil tank, and the inlet P3 of the first proportional relief valve is connected to the outlet P1 of the large flow pump; the second oil circuit also includes a second proportional relief valve, the inlet P6 of the second proportional relief valve is connected to the outlet P2 of the small flow pump, and the outlet T4 of the second proportional relief valve is connected to the oil tank.

[0011] Further, the pressure setting value of the second proportional relief valve is the load pressure value of the oil cylinder, and the ratio of the pressure setting value of the second proportional relief valve to the pressure setting value of the first proportional relief valve is equal to V1:V2.

[0012] Furthermore, the first oil circuit also includes a first safety valve, an inlet P4 of the first safety valve is connected to the outlet P1 of the large flow pump, and an outlet T2 of the first safety valve is connected to the oil tank; the second oil circuit also includes a second safety valve, an inlet P5 of the second safety valve is connected to the outlet P2 of the small flow pump, and an outlet T3 of the second safety valve is connected to the oil tank.

[0013] Furthermore, the maximum load pressure of the first proportional relief valve and the second proportional relief valve is 30 MPa, and the pressure of the first safety valve and the second safety valve is set to 32±0.5 MPa.

[0014] According to another aspect of the present invention, a control method for a micro-flow hydraulic transmission system is provided, which comprises the micro-flow hydraulic transmission system described above,

[0015] When the micro-flow hydraulic transmission system requires a large flow and the oil cylinder extends, the large flow pump and the small flow pump are started, the first electromagnetic reversing valve is in the left position, and the second electromagnetic reversing valve is in the right position. The first oil circuit is: S1-P1-A1-B1-A2-B2-P7-A4, and the second oil circuit is: S2-P2-A3-B3-T5-A4. The pressure oil of the first oil circuit merges with the pressure oil of the second oil circuit at A4. The pressure oil circuit after merging is: A4-P8-A5-A6, and the return oil circuit is: B6-B5-T6-tank. The flow after merging is adjusted by adjusting the proportional speed regulating valve to complete the large stroke control of the oil cylinder;

[0016] When the micro-flow hydraulic transmission system requires a small flow and the cylinder extends, the large-flow pump and the small-flow pump are started, the first solenoid reversing valve is in the right position, and the second solenoid reversing valve is in the right position. The large-flow oil circuit is: S1-P1-A1-B1-A2-B2-P7-B4-oil tank; the small-flow oil circuit is S2-P2-A3-B3-T5-A4-P8-A5-A6, and the return oil circuit is: B6-B5-T6-oil tank. The flow of the first hydraulic motor is controlled by the proportional speed control valve, so as to realize the small flow control of the second hydraulic motor in proportion, and complete the high-precision micro-motion control of the cylinder.

[0017] The present invention has the following beneficial effects:

[0018] The micro-flow hydraulic transmission system of the present invention is driven by the first hydraulic motor to drive the second hydraulic motor to operate. The large-flow pressure oil provided by the first oil circuit and the small-flow pressure oil provided by the second oil circuit can merge through the outlet A4 of the first electromagnetic reversing valve. The merged pressure oil enters the inlet P8 of the second electromagnetic reversing valve, and then enters the oil cylinder 12 through A5 / B5 of the second electromagnetic reversing valve, thereby realizing a large-stroke drive of the oil cylinder; the large-flow pressure oil provided by the first oil circuit enters the mailbox through the outlet B4 of the first electromagnetic reversing valve, and the small-flow pressure oil provided by the second oil circuit enters the inlet P8 of the second electromagnetic reversing valve through the outlet A4 of the first electromagnetic reversing valve, and then enters the oil cylinder through A5 / B5 of the second electromagnetic reversing valve, thereby realizing high-precision micro-motion control of the oil cylinder; by adjusting the flow ratio of the first oil circuit and the second oil circuit, stable regulation of different micro-flow levels can be achieved, and flow regulation of the entire flow range starting from 0L / min can be achieved, thereby improving the control accuracy of the hydraulic transmission system, with a simple structure, low cost, high pressure resistance, and a wide range of applications.

[0019] In addition to the above-described purposes, features and advantages, the present invention has other purposes, features and advantages. The present invention will be further described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0021] Figure 1 It is a structural schematic diagram of a micro-flow hydraulic transmission system according to a preferred embodiment of the present invention.

[0022] Legend:

[0023] 1. Large flow pump; 2. Small flow pump; 3. First proportional overflow valve; 4. First safety valve; 5. Second safety valve; 6. Second proportional overflow valve; 7. Proportional speed control valve; 8. First hydraulic motor; 9. Second hydraulic motor; 10. First solenoid reversing valve; 11. Second solenoid reversing valve; 12. Oil cylinder; 13. Oil tank. DETAILED DESCRIPTION

[0024] The embodiments of the present invention are described in detail below with reference to the accompanying drawings. However, the present invention can be implemented in many different ways as defined and covered below.

[0025] like Figure 1As shown, the micro-flow hydraulic transmission system of this embodiment includes a first oil circuit for providing a large flow of pressure oil, a second oil circuit for providing a small flow of pressure oil, a first electromagnetic reversing valve 10, a second electromagnetic reversing valve 11, an oil cylinder 12 and an oil tank 13; the oil inlet end of the first oil circuit is connected to the oil tank 13, and the oil outlet end of the first oil circuit is connected to the P7 port of the first electromagnetic reversing valve 10; the oil inlet end of the second oil circuit is connected to the oil tank 13, and the oil outlet end of the second oil circuit is connected to the T5 port of the first electromagnetic reversing valve 10; the first electromagnetic reversing valve 1 0 is connected with the inlet P8 of the second electromagnetic reversing valve 11, the outlet B4 of the first electromagnetic reversing valve 10 and the return oil port T6 of the second electromagnetic reversing valve 11 are connected with the oil tank 13, the outlet A5 of the second electromagnetic reversing valve 11 is connected with the inlet A6 of the oil cylinder 12, and the outlet B5 of the second electromagnetic reversing valve 11 is connected with the inlet B6 of the oil cylinder 12; the first hydraulic motor 8 is arranged on the first oil circuit, and the second hydraulic motor 9 is arranged on the second oil circuit, and the rotor of the first hydraulic motor 8 is connected with the rotor of the second hydraulic motor 9.

[0026] In the micro-flow hydraulic transmission system of the present embodiment, the first hydraulic motor 8 drives the second hydraulic motor 9 to operate, and the large-flow pressure oil provided by the first oil circuit and the small-flow pressure oil provided by the second oil circuit can merge through the outlet A4 of the first electromagnetic reversing valve 10, and the merged pressure oil enters the inlet P8 of the second electromagnetic reversing valve 11, and then enters the oil cylinder 12 through A5 / B5 of the second electromagnetic reversing valve 11, thereby realizing the large-stroke drive of the oil cylinder 12; the large-flow pressure oil provided by the first oil circuit enters the mailbox through the outlet B4 of the first electromagnetic reversing valve 10, and the second The small-flow pressure oil provided by the oil circuit enters the inlet P8 of the second solenoid reversing valve 11 through the outlet A4 of the first solenoid reversing valve 10, and then enters the oil cylinder 12 through A5 / B5 of the second solenoid reversing valve 11, thereby realizing high-precision micro-motion control of the oil cylinder 12; by adjusting the flow ratio of the first oil circuit and the second oil circuit, stable regulation of different small flow levels can be achieved, and flow regulation of the entire flow range starting from 0L / min can be achieved, thereby improving the control accuracy of the hydraulic transmission system, with simple structure, low cost, high pressure resistance and wide application range.

[0027] In this embodiment, a large flow pump 1 and a proportional speed regulating valve 7 are also arranged on the first oil circuit, the oil suction port S1 of the large flow pump 1 is connected to the oil tank 13, the outlet P1 of the large flow pump 1 is connected to the inlet A1 of the proportional speed regulating valve 7, the outlet B1 of the proportional speed regulating valve 7 is connected to the inlet A2 of the first hydraulic motor 8, and the outlet B2 of the first hydraulic motor 8 is connected to the P7 port of the first electromagnetic reversing valve 10; a small flow pump 2 is also arranged on the second oil circuit, the oil suction port S2 of the small flow pump 2 is connected to the oil tank 13, and the outlet P2 of the small flow pump 2 is connected to the second hydraulic motor 8. The inlet A3 of the first hydraulic motor 9 is connected, and the outlet B3 of the second hydraulic motor 9 is connected to the T5 port of the first electromagnetic reversing valve 10; the displacement V1 of the first hydraulic motor 8 is greater than the displacement V2 of the second hydraulic motor 9, and the rotor of the first hydraulic motor 8 is connected to the rotor of the second hydraulic motor 9 through a coupling; the flow rate regulation of the whole flow range starting from 0L / min is achieved through the proportional speed control valve 7, and the flow rate ratio of the first oil circuit and the second oil circuit can be adjusted by adjusting the displacement ratio of the first hydraulic motor 8 and the second hydraulic motor 9, which has a simple structure and low cost.

[0028] In this embodiment, the rotor of the first hydraulic motor 8 is connected to the rotor of the second hydraulic motor 9 via a reducer. Compared with the case where the rotor of the first hydraulic motor 8 is connected to the rotor of the second hydraulic motor 9 via a coupling, when the rotation speed of the first hydraulic motor 8 is the same, the displacement of the second hydraulic motor 9 is smaller, thereby reducing the minimum flow rate of the second oil circuit, which can further increase the displacement ratio of the first hydraulic motor 8 to the second hydraulic motor 9 and improve the accuracy of the micro-control of the cylinder 12.

[0029] In this embodiment, a large flow pump 1 and a proportional speed regulating valve 7 are also arranged on the first oil circuit, the oil suction port S1 of the large flow pump 1 is connected to the oil tank 13, the outlet P1 of the large flow pump 1 is connected to the inlet A1 of the proportional speed regulating valve 7, the outlet B1 of the proportional speed regulating valve 7 is connected to the inlet A2 of the first hydraulic motor 8, and the outlet B2 of the first hydraulic motor 8 is connected to the P7 port of the first electromagnetic reversing valve 10; a small flow pump 2 is also arranged on the second oil circuit, the oil suction port S2 of the small flow pump 2 is connected to the oil tank 13, and the outlet P2 of the small flow pump 2 is connected to the second hydraulic motor 8. 9 is connected to the inlet A3, and the outlet B3 of the second hydraulic motor 9 is connected to the T5 port of the first electromagnetic reversing valve 10; the displacement V1 of the first hydraulic motor 8 is equal to the displacement V2 of the second hydraulic motor 9, and the rotor of the first hydraulic motor 8 is connected to the rotor of the second hydraulic motor 9 through a reducer. The reducer enables the first hydraulic motor 8 and the second hydraulic motor 9 to achieve a speed difference, thereby realizing large flow in the first oil circuit and small flow in the second oil circuit. When there are no hydraulic motors with different displacements, high-precision control of the hydraulic transmission system can also be achieved.

[0030] In this embodiment, the pressure oil flow rate at the oil outlet of the first oil circuit is V3, and the pressure oil flow rate at the oil outlet of the second oil circuit is V4, and the range of V3:V4 is 10:1 to 1000:1. When the displacement V1 of the first hydraulic motor 8 is greater than the displacement V2 of the second hydraulic motor 9, the rotor of the first hydraulic motor 8 is coaxially connected with the rotor of the second hydraulic motor 9 through a coupling, when V1:V2=20:1, the displacement of the first hydraulic motor 8 is 1L / min, then the displacement of the second hydraulic motor 9 is 0.05L / min, at this time, V3:V4=20:1, and the flow rate of the micro-control of the system lifting cylinder 12 is 0.05L / min; it can be understood that if the rotor of the first hydraulic motor 8 is connected with the rotor of the second hydraulic motor 9 through a reducer, then the displacement of the second hydraulic motor 9 is 0.05L / min divided by the reduction ratio. When the displacement V1 of the first hydraulic motor 8 is equal to the displacement V2 of the second hydraulic motor 9, the flow rate of the first oil circuit is 1 L / min, and the flow rate of the second oil circuit is 0.05 L / min, then V3:V4=20:1, and the reduction ratio of the reducer is 20:1.

[0031] In this embodiment, the first oil circuit also includes a first proportional relief valve 3, the outlet T1 of the first proportional relief valve 3 is connected to the oil tank 13, and the inlet P3 of the first proportional relief valve 3 is connected to the outlet P1 of the large flow pump 1; the second oil circuit also includes a second proportional relief valve 6, the inlet P6 of the second proportional relief valve 6 is connected to the outlet P2 of the small flow pump 2, and the outlet T4 of the second proportional relief valve 6 is connected to the oil tank 13, which can accurately control the pressure of the first oil circuit and the second oil circuit to ensure the stable operation of the micro-flow hydraulic transmission system.

[0032] In this embodiment, the pressure setting of the first proportional relief valve 3 is set according to the displacement ratio of the two motors, and it is necessary to ensure that the first hydraulic motor 8 can drag the second hydraulic motor 9. The pressure setting value of the second proportional relief valve 6 is the load pressure value of the cylinder 12. The ratio of the pressure setting value of the second proportional relief valve 6 to the pressure setting value of the first proportional relief valve 3 is equal to V1:V2. At this time, the heat generation can be reduced, thereby reducing the energy consumption of the micro-flow hydraulic transmission system.

[0033] In this embodiment, the first oil circuit also includes a first safety valve 4, the inlet P4 of the first safety valve 4 is connected to the outlet P1 of the large flow pump 1, and the outlet T2 of the first safety valve 4 is connected to the oil tank 13; the second oil circuit also includes a second safety valve 5, the inlet P5 of the second safety valve 5 is connected to the outlet P2 of the small flow pump 2, and the outlet T3 of the second safety valve 5 is connected to the oil tank 13, which can release excess pressure and avoid damage to the first hydraulic motor 8 and the second hydraulic motor 9.

[0034] In this embodiment, the maximum load pressure of the first proportional relief valve 3 and the second proportional relief valve 6 is 30 MPa, and the pressure of the first safety valve 4 and the second safety valve 5 is set to 32±0.5 MPa.

[0035] A control method for a micro-flow hydraulic transmission system, comprising the micro-flow hydraulic transmission system described above,

[0036] When the micro-flow hydraulic transmission system requires a large flow and the oil cylinder 12 extends, the large-flow pump 1 and the small-flow pump 2 are started, the first electromagnetic reversing valve 10 is in the left position, and the second electromagnetic reversing valve 11 is in the right position. The first oil circuit is: S1-P1-A1-B1-A2-B2-P7-A4, and the second oil circuit is: S2-P2-A3-B3-T5-A4. The pressure oil of the first oil circuit merges with the pressure oil of the second oil circuit at A4. The pressure oil circuit after merging is: A4-P8-A5-A6, and the return oil circuit is: B6-B5-T6-oil tank 13. The flow after merging is adjusted by adjusting the proportional speed regulating valve 7 to complete the large stroke control of the oil cylinder 12;

[0037] When the micro-flow hydraulic transmission system requires a micro-flow and the cylinder 12 is extended, the large-flow pump 1 and the small-flow pump 2 are started, the first solenoid reversing valve 10 is in the right position, and the second solenoid reversing valve 11 is in the right position. The large-flow oil circuit is: S1-P1-A1-B1-A2-B2-P7-B4-oil tank 13; the micro-flow oil circuit is S2-P2-A3-B3-T5-A4-P8-A5-A6, and the return oil circuit is: B6-B5-T6-oil tank 13. The flow of the first hydraulic motor 8 is controlled by the proportional speed control valve 7, so as to realize the micro-flow control of the second hydraulic motor 9 in proportion, and complete the high-precision micro-motion control of the cylinder 12.

[0038] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A micro-flow hydraulic transmission system, characterized in that: It comprises a first oil circuit for providing high-flow pressure oil, a second oil circuit for providing low-flow pressure oil, a first electromagnetic reversing valve (10), a second electromagnetic reversing valve (11), an oil cylinder (12) and an oil tank (13); The oil inlet end of the first oil circuit is connected to the oil tank (13), and the oil outlet end of the first oil circuit is connected to the P7 port of the first electromagnetic reversing valve (10); The oil inlet end of the second oil circuit is connected to the oil tank (13), and the oil outlet end of the second oil circuit is connected to the T5 port of the first electromagnetic reversing valve (10); The outlet A4 of the first electromagnetic reversing valve (10) is in communication with the inlet P8 of the second electromagnetic reversing valve (11); the outlet B4 of the first electromagnetic reversing valve (10) and the oil return port T6 of the second electromagnetic reversing valve (11) are in communication with the oil tank (13); the outlet A5 of the second electromagnetic reversing valve (11) is in communication with the inlet A6 of the oil cylinder (12); and the outlet B5 of the second electromagnetic reversing valve (11) is in communication with the inlet B6 of the oil cylinder (12); A first hydraulic motor (8) is arranged on the first oil circuit, a second hydraulic motor (9) is arranged on the second oil circuit, and a rotor of the first hydraulic motor (8) is connected to a rotor of the second hydraulic motor (9).

2. The micro-flow hydraulic transmission system according to claim 1, characterized in that: A large flow pump (1) and a proportional speed regulating valve (7) are also arranged on the first oil circuit. The oil suction port S1 of the large flow pump (1) is connected to the oil tank (13), the outlet P1 of the large flow pump (1) is connected to the inlet A1 of the proportional speed regulating valve (7), the outlet B1 of the proportional speed regulating valve (7) is connected to the inlet A2 of the first hydraulic motor (8), and the outlet B2 of the first hydraulic motor (8) is connected to the P7 port of the first electromagnetic reversing valve (10); A small flow pump (2) is also arranged on the second oil circuit, the oil suction port S2 of the small flow pump (2) is connected to the oil tank (13), the outlet P2 of the small flow pump (2) is connected to the inlet A3 of the second hydraulic motor (9), and the outlet B3 of the second hydraulic motor (9) is connected to the T5 port of the first electromagnetic reversing valve (10); The displacement V1 of the first hydraulic motor (8) is greater than the displacement V2 of the second hydraulic motor (9).

3. The micro-flow hydraulic transmission system according to claim 2, characterized in that: The rotor of the first hydraulic motor (8) is connected to the rotor of the second hydraulic motor (9) via a reducer.

4. The micro-flow hydraulic transmission system according to claim 1, characterized in that: A large flow pump (1) and a proportional speed regulating valve (7) are also arranged on the first oil circuit. The oil suction port S1 of the large flow pump (1) is connected to the oil tank (13), the outlet P1 of the large flow pump (1) is connected to the inlet A1 of the proportional speed regulating valve (7), the outlet B1 of the proportional speed regulating valve (7) is connected to the inlet A2 of the first hydraulic motor (8), and the outlet B2 of the first hydraulic motor (8) is connected to the P7 port of the first electromagnetic reversing valve (10); A small flow pump (2) is also arranged on the second oil circuit, the oil suction port S2 of the small flow pump (2) is connected to the oil tank (13), the outlet P2 of the small flow pump (2) is connected to the inlet A3 of the second hydraulic motor (9), and the outlet B3 of the second hydraulic motor (9) is connected to the T5 port of the first electromagnetic reversing valve (10); The displacement V1 of the first hydraulic motor (8) is equal to the displacement V2 of the second hydraulic motor (9), and the rotor of the first hydraulic motor (8) is connected to the rotor of the second hydraulic motor (9) via a reducer.

5. The micro-flow hydraulic transmission system according to any one of claims 1 to 4, characterized in that: The pressure oil flow rate of the oil outlet end of the first oil circuit is V3, the pressure oil flow rate of the oil outlet end of the second oil circuit is V4, and the range of V3:V4 is 10:1 to 1000:

1.

6. The micro-flow hydraulic transmission system according to claim 5, characterized in that: The first oil circuit further comprises a first proportional relief valve (3), the outlet T1 of the first proportional relief valve (3) being connected to the oil tank (13), and the inlet P3 of the first proportional relief valve (3) being connected to the outlet P1 of the large flow pump (1); the second oil circuit further comprises a second proportional relief valve (6), the inlet P6 of the second proportional relief valve (6) being connected to the outlet P2 of the small flow pump (2), and the outlet T4 of the second proportional relief valve (6) being connected to the oil tank (13).

7. The micro-flow hydraulic transmission system according to claim 6, characterized in that: The pressure setting value of the second proportional relief valve (6) is the load pressure value of the oil cylinder (12), and the ratio of the pressure setting value of the second proportional relief valve (6) to the pressure setting value of the first proportional relief valve (3) is equal to V1:V2.

8. The micro-flow hydraulic transmission system according to claim 7, characterized in that: The first oil circuit further comprises a first safety valve (4), an inlet P4 of the first safety valve (4) being connected to an outlet P1 of the large flow pump (1), and an outlet T2 of the first safety valve (4) being connected to the oil tank (13); the second oil circuit further comprises a second safety valve (5), an inlet P5 of the second safety valve (5) being connected to an outlet P2 of the small flow pump (2), and an outlet T3 of the second safety valve (5) being connected to the oil tank (13).

9. The micro-flow hydraulic transmission system according to claim 8, characterized in that: The maximum load pressure of the first proportional relief valve (3) and the second proportional relief valve (6) is 30 MPa, and the pressure of the first safety valve (4) and the second safety valve (5) is set to 32±0.5 MPa.

10. A control method for a micro-flow hydraulic transmission system, characterized in that: A micro-flow hydraulic transmission system comprising any one of claims 1 to 9, When the micro-flow hydraulic transmission system requires a large flow and the oil cylinder (12) extends, the large flow pump (1) and the small flow pump (2) are started, the first electromagnetic reversing valve (10) is in the left position, the second electromagnetic reversing valve (11) is in the right position, the first oil circuit is: S1-P1-A1-B1-A2-B2-P7-A4, the second oil circuit is: S2-P2-A3-B3-T5-A4, the pressure oil of the first oil circuit and the pressure oil of the second oil circuit merge at A4, the pressure oil circuit after merging is: A4-P8-A5-A6, the return oil circuit is: B6-B5-T6-oil tank (13), the flow after merging is adjusted by adjusting the proportional speed regulating valve (7), and the large stroke control of the oil cylinder (12) is completed; When a micro-flow hydraulic transmission system requires a micro-flow and the oil cylinder (12) extends, a large-flow pump (1) and a small-flow pump (2) are started, the first electromagnetic reversing valve (10) is in the right position, the second electromagnetic reversing valve (11) is in the right position, the large-flow oil circuit is: S1-P1-A1-B1-A2-B2-P7-B4-oil tank (13); the micro-flow oil circuit is: S2-P2-A3-B3-T5-A4-P8-A5-A6, the return oil circuit is: B6-B5-T6-oil tank (13), the flow of the first hydraulic motor (8) is controlled by the proportional speed regulating valve (7), so as to realize the micro-flow control of the second hydraulic motor (9) in proportion, and complete the high-precision micro-motion control of the oil cylinder (12).

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