Multi-pump multi-actuator loop and engineering machinery

Abstract

The invention discloses a multi-pump multi-actuator loop and engineering machinery. The multi-pump multi-actuator loop comprises a first loop, a second loop, a third loop, a first variable pump, a second variable pump, a third variable pump, a motor, a first oil cylinder, a second oil cylinder, a third oil cylinder and an oil return path, the first variable pump is connected with an oil inlet of the first loop, and an oil outlet of the first loop is connected with the first oil cylinder and connected with the second oil cylinder and the third oil cylinder through the second loop. The second variable pump is connected with an oil inlet of the second loop, and an oil outlet of the second loop is connected with the second oil cylinder and the third oil cylinder; the third variable pump is connected with an oil inlet of the third loop; an oil outlet of the third loop is connected with the motor and is connected with the third oil cylinder through the second loop; and the oil return path is respectively connected with oil return ports of the first loop, the second loop and the third loop. Independent control over the motor, the first oil cylinder, the second oil cylinder and the third oil cylinder can be achieved, the coupling loss is reduced, the flexibility of a loop is improved, and then the energy efficiency level of the whole machine is improved.

Description

Technical Field

[0001] This invention belongs to the field of hydraulic transmission and control technology, specifically relating to a multi-pump multi-actuator circuit and engineering machinery. Background Technology

[0002] For mobile machinery, especially earthmoving machinery such as hydraulic excavators that require long-term continuous operation, high energy efficiency and low losses are the core goals for continuous upgrading and iteration. Taking hydraulic excavators as an example, the energy consumption of the hydraulic system accounts for about 85% of the total energy consumption of the machine. Reducing hydraulic circuit losses is an important direction for improving the overall energy efficiency of the machine.

[0003] The existing hydraulic system has the following five problems:

[0004] (1) The circuit is highly coupled, and the difference between loads during the combined operation of the whole machine results in high coupling throttling loss;

[0005] (2) When large inertia slewing is involved in compound actions, the slewing starting torque is low and the acceleration is slow. Taking an excavator as an example, when slewing and boom lifting are combined for loading, the slow acceleration of slewing affects the improvement of work efficiency.

[0006] (3) The conventional hydraulic valve has rigid coupling between the inlet and outlet throttle ports of each working link, which cannot be controlled independently, resulting in additional pressure loss;

[0007] (4) Insufficient utilization of gravitational potential energy. Taking excavators as an example, there is a contradiction between improving the utilization rate of the potential energy of the boom falling and carrying out the impact compaction operation of the boom falling to the ground, and they cannot be achieved at the same time.

[0008] (5) Existing technology restricts the further improvement of the overall performance, and there is an urgent need to design a new circuit to meet the development needs of high-efficiency equipment.

[0009] Taking excavators as an example, multi-pump multi-actuator circuits currently commonly use 2-pump 2-circuit throttling hydraulic systems. The circuit includes multiple actuators such as hydraulic cylinders and hydraulic motors, and they need to operate simultaneously.

[0010] (1) In terms of the coordination of multi-action compound operation, there are two main methods: ① Set a controllable throttling element at the oil inlet of the hydraulic valve in the low-load working link to increase the working pressure of the main circuit and ensure the coordinated operation of multiple working devices; ② Perform electro-proportional continuous control on the stroke of the valve core in the low-load working link of the hydraulic valve, and increase the working pressure of the main circuit by throttling the oil inlet of the valve core to ensure the coordinated operation of multiple working devices.

[0011] (2) Large inertia slewing drive. Taking the excavator slewing + boom lifting loading as an example, there are two ways to solve the coordination problem: ① Set a controllable oil inlet throttling element before the hydraulic valve slewing linkage to avoid the slewing pressure drop causing action misalignment in the later stage of slewing + boom lifting; ② Control the output flow of the two main pumps to realize the pre-distribution of the flow of the two circuits and ensure the coordination of loading action.

[0012] (3) The oil inlet and return throttle ports of each working link of the hydraulic valve are rigidly connected on the valve core, and the operation of the working device is controlled by the phase sequence relationship and area matching between the two.

[0013] (4) Gravitational potential energy regeneration and utilization, taking excavators as an example, there are two main methods: ① A differential circuit is formed by the hollow boom valve core to realize the recycling of the return oil flow from the piston chamber of the boom cylinder to the small chamber; ② A reversing valve directs the boom falling flow to specific working devices such as the stick to improve the speed of compound action. The oil intake is mainly achieved through the replenishment method. Summary of the Invention

[0014] To address the aforementioned issues, this invention proposes a multi-pump, multi-actuator circuit and engineering machinery, which enables independent control of the motor, the first cylinder, the second cylinder, and the third cylinder, reducing coupling losses, improving circuit flexibility, and thus enhancing the overall energy efficiency of the machine.

[0015] To achieve the above-mentioned technical objectives and effects, the present invention is implemented through the following technical solution:

[0016] In a first aspect, the present invention provides a multi-pump multi-actuator circuit, comprising: a first circuit (1), a second circuit (2), a third circuit (3), a first variable pump (4), a second variable pump (5), a third variable pump (6), a motor (7), a first cylinder (8), a second cylinder (9), a third cylinder (10), and a return oil circuit (T).

[0017] The first variable pump (4) is connected to the oil inlet of the first circuit (1), the oil outlet of the first circuit (1) is connected to the first oil cylinder (8), and is connected to the second oil cylinder (9) and the third oil cylinder (10) respectively through the second circuit (2);

[0018] The second variable pump (5) is connected to the oil inlet of the second circuit (2), and the oil outlet of the second circuit (2) is connected to the second oil cylinder (9) and the third oil cylinder (10) respectively;

[0019] The third variable pump (6) is connected to the oil inlet of the third circuit (3); the oil outlet of the third circuit (3) is connected to the motor (7) and connected to the third cylinder (10) through the second circuit (2);

[0020] The return oil circuit (T) is connected to the return oil ports of the first circuit (1), the second circuit (2), and the third circuit (3), respectively.

[0021] In a second aspect, the present invention provides an engineering machine comprising the multi-pump multi-actuator circuit described in any one of the first aspects.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] In this invention, multiple variable pumps, cylinders, motors and directional valves are combined through circuit design. The oil inlet and return of each working chamber are controlled independently, which reduces coupling loss, improves circuit flexibility, and eliminates the problems of rigid connection between pumps and working circuits, poor circuit flexibility, high coupling pressure loss and low overall energy efficiency in conventional 2-pump 2-circuit hydraulic systems. Attached Figure Description

[0024] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein:

[0025] Figure 1 This is a schematic diagram of the principle of a multi-pump multi-actuator circuit according to an embodiment of the present invention;

[0026] Figure 2 This is a schematic diagram illustrating the working principle of one embodiment of the present invention, namely, mode 1.

[0027] Figure 3 This is a schematic diagram illustrating the working principle of mode 2 of one embodiment of the present invention;

[0028] Figure 4 This is a schematic diagram illustrating the working principle of mode 3 of one embodiment of the present invention;

[0029] Figure 5 This is a schematic diagram illustrating the working principle of mode 4 in one embodiment of the present invention;

[0030] Figure 6 This is a schematic diagram illustrating the working principle of mode 5 of one embodiment of the present invention;

[0031] Figure 7 This is a schematic diagram illustrating the working principle of mode 6 of one embodiment of the present invention. Detailed Implementation

[0032] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may include different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0034] In the description of this invention, "several" means one or more, "multiple" means two or more, "greater than," "less than," and "exceeding" are understood to exclude the stated number, while "above," "below," and "within" are understood to include the stated number. The use of "first" and "second" in the description is merely for distinguishing technical features and should not be construed as indicating or implying relative importance, or implicitly indicating the number of indicated technical features, or implicitly indicating the order of the indicated technical features.

[0035] In the description of this invention, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0036] The application principle of the present invention will be described in detail below with reference to the accompanying drawings.

[0037] Example 1

[0038] This invention provides a multi-pump, multi-actuator circuit, such as... Figure 1 The diagram shown is a schematic of the multi-pump multi-actuator circuit, including a first circuit 1, a second circuit 2, a third circuit 3, a first variable pump 4, a second variable pump 5, a third variable pump 6, a motor 7, a first hydraulic cylinder 8, a second hydraulic cylinder 9, a third hydraulic cylinder 10, an oil return circuit T, and an oil tank 112.

[0039] The first circuit 1 includes a first circuit first directional valve 11, a first circuit second directional valve 12, a first circuit third directional valve 13, a first circuit fourth directional valve 14, a first circuit fifth directional valve 15, a first circuit first check valve 16, a first circuit second check valve 17, a first circuit third check valve 18, a first circuit fourth check valve 19, a first circuit fifth check valve 110, a first circuit sixth check valve 111, and a first oil inlet circuit P1.

[0040] The second circuit 2 includes a second circuit first directional valve 21, a second circuit second directional valve 22, a second circuit third directional valve 23, a second circuit fourth directional valve 24, a second circuit first check valve 25, a second circuit second check valve 26, a second circuit third check valve 27, a second circuit fourth check valve 28, and a second oil inlet circuit P2.

[0041] The third circuit 3 includes a third circuit first reversing valve 31, a third circuit second reversing valve 32, a third circuit third reversing valve 33, a third circuit first check valve 34, a third circuit second check valve 35, a third oil inlet circuit P3, a first oil supply circuit P32a, and a second oil supply circuit P32b.

[0042] The connection method of the multi-pump multi-actuator circuit in this embodiment of the invention is as follows:

[0043] The first variable pump 4 is connected via its outlet 4a to the inlet 11p of the first directional valve 11 in the first circuit and the sixth check valve 111 in the first circuit. The sixth check valve 111 in the first circuit is connected via the first inlet oil passage P1 to the first check valve 16, the third check valve 18, and the fifth check valve 110 in the first circuit. The return port 11t of the first directional valve 11 in the first circuit is connected to the return oil passage T. The oil inlet 12p of the second reversing valve 12 in the first circuit is connected to the fifth check valve 110 in the first circuit, and its return oil port 12t is connected to the return oil circuit T. The working oil port 12a of the second reversing valve 12 in the first circuit is connected to the oil inlet 13p of the third reversing valve 13 in the first circuit, the oil inlet 14p of the fourth reversing valve 14 in the first circuit, the working oil port 22a of the second reversing valve 22 in the second circuit, and the large chamber working oil port 10a of the third cylinder 10. The working oil port 12a of the second reversing valve 12 in the first circuit is also connected to the first working oil port 32a of the second reversing valve 32 in the third circuit via the first oil supply circuit P32a. The working port 13a of the third directional valve 13 in the first circuit is connected to the third check valve 18 in the first circuit, and is connected to the first oil inlet circuit P1 through the third check valve 18 in the first circuit; at the same time, the working port 13a of the third directional valve 13 in the first circuit is also connected to the second check valve 17 in the first circuit, and is connected to the second oil inlet circuit P2 through the second check valve 17 in the first circuit. The working port 14a of the fourth directional valve 14 in the first circuit is connected to the fourth check valve 19 in the first circuit, and is connected to the working port 23b of the third directional valve 23 in the second circuit, the fourth check valve 28 in the second circuit, and the oil inlet port 10b of the third cylinder 10 through the fourth check valve 19 in the first circuit; the fourth check valve 19 in the first circuit is connected to the second working port 32b of the second directional valve 32 in the third circuit through the second oil supply circuit P32b. The inlet 15p of the fifth directional valve 15 in the first circuit is connected to the first check valve 16 in the first circuit, its return port 15t is connected to the return oil circuit T, its first working port 15a is connected to the small chamber inlet 8a of the first cylinder 8, and its second working port 15b is connected to the large chamber working port 8b of the first cylinder 8. In the second circuit 2, the second variable pump 5 is connected to the inlet 21p of the first directional valve 21 in the second circuit and the third check valve 27 in the second circuit via its outlet 5a. The third check valve 27 in the second circuit is connected to the first check valve 25 and the second check valve 26 in the second circuit via the second inlet oil circuit P2. The fourth check valve 28 in the second circuit is connected to the return oil circuit T. The return port 21t of the first directional valve 21 in the second circuit is connected to the return oil circuit T. The oil inlet 22p of the second reversing valve 22 in the second circuit is connected to the oil inlet 23p of the second check valve 26 and the third reversing valve 23 in the second circuit, and its return port 22t is connected to the return oil circuit T. The oil return port 23t of the third reversing valve 23 in the second circuit is connected to the return oil circuit T.The inlet 24p of the fourth directional valve 24 in the second circuit is connected to the first check valve 25 in the second circuit, its return port 24t is connected to the return oil circuit T, its first working port 24a is connected to the large chamber working port 9a of the second cylinder 9, and its second working port 24b is connected to the small chamber working port 9b of the second cylinder 9. In the third circuit 3, the third variable pump 6 is connected to the third directional valve 33, the first check valve 34, and the second check valve 35 of the third circuit via its outlet 6a and the third inlet oil circuit P3. The inlet 31p of the first directional valve 31 in the third circuit is connected to the first check valve 34 in the third circuit, its return port 31t is connected to the return oil circuit T, its first working port 31a is connected to the first oil port 7a of the motor 7, and its second working port 31b is connected to the second oil port 7b of the motor 7. The inlet 32p of the second directional valve 32 in the third circuit is connected to the second check valve 35 in the third circuit. The return port 33t of the third reversing valve 33 in the third circuit is connected to the return oil circuit T. The first oil port 7a and the second oil port 7b of the motor 7 are the two working oil ports of the motor 7. When oil enters the motor 7 through the first oil port 7a, the oil pushes the motor to rotate clockwise, and the oil flows out from the second oil port 7b of the motor 7. Similarly, when oil enters the motor 7 through the second oil port 7b of the motor 7, the oil pushes the motor to rotate clockwise, and the oil flows out from the first oil port 7a of the motor 7.

[0044] The working principle and control method of this circuit are as follows:

[0045] Circuit 1 operation mode 1 involves the independent operation of motor 7, first cylinder 8, and third cylinder 10, see [link / description]. Figure 2 .

[0046] The first directional valve 11 of the first circuit switches to the first working position X under the pressure of the control chamber 11a, and the oil passage 11b between its inlet 11p and return port 11t is closed. The fifth directional valve 15 of the first circuit switches to the first working position X under the pressure of the control chamber 15c, and the oil passage 15e between its inlet 15p and the first working oil port 15a is opened, and the oil passage 15f between its second working oil port 15b and return port 15t is opened. Oil from the first variable pump 4 flows through port 4a, the sixth check valve 111 of the first circuit, the first inlet oil line P1, the first check valve 16 of the first circuit, the inlet port 15p of the fifth directional valve 15 of the first circuit, the oil line 15e, and the first working port 15a into the small chamber inlet port 8a of the first cylinder 8. Oil returning from the large chamber working port 8b of the first cylinder 8 flows through the second working port 15b and the return port 15t of the fifth directional valve 15 of the first circuit into the return oil line T and then back to the oil tank 112, causing the first cylinder 8 to retract. Similarly, when the fifth directional valve 15 of the first circuit is switched to the second working position Y under the pressure of the control chamber 15d, the first cylinder 8 extends.

[0047] The first directional valve 21 of the second circuit switches to the first working position X under the pressure of the control chamber 21a, closing the oil passage 21b between the inlet 21p and the return port 21t. When the second directional valve 22 of the second circuit switches to the first working position X under the pressure of the control chamber 22c, the oil passage 22b between the inlet 22p and the working port 22a opens. The third directional valve 23 of the second circuit switches to the second working position Y under the pressure of the control chamber 23d, opening the oil passage 23e between the working port 23b and the return port 23t. Oil from the second variable pump 5 flows through port 5a, the third check valve 27 of the second circuit, the inlet oil line P2, the second check valve 26 of the second circuit, the inlet port 22p of the second directional valve 22 of the second circuit, the oil line 22b, and the working port 22a into the large chamber working port 10a of the third cylinder 10. Oil returning from the small chamber working port 10b of the third cylinder 10 flows through the working port 23b and the return port 23t of the third directional valve 23 of the second circuit into the return oil line T and then back to the oil tank 112, causing the third cylinder 10 to extend. Similarly, when the second directional valve 22 of the second circuit switches to the second working position Y under the pressure of the control chamber 22d, the oil line 22e between the working port 22a and the return port 22t opens. When the third directional valve 23 of the second circuit switches to the first working position X under the pressure of the control chamber 23c, the oil line 23a between the inlet port 23p and the working port 23b opens. The oil from the second variable pump 5 flows through port 5a, the third check valve 27 of the second circuit, the oil inlet P2, the second check valve 26 of the second circuit, the oil inlet 23p of the third directional valve 23 of the second circuit, the oil passage 23a, and the working port 23b into the small chamber working port 10b of the third cylinder 10. The oil returning from the large chamber working port 10a of the third cylinder 10 flows through the working port 22a and the return port 22t of the second directional valve 22 of the second circuit into the return oil passage T and then back to the oil tank 112, causing the third cylinder 10 to retract.

[0048] The third directional valve 33 of the third circuit switches to the first working position X under the pressure of the control chamber 33a, and the oil passage 33b between the oil inlet 33p and the oil return port 33t is closed. When the first directional valve 31 of the third circuit switches to the second working position Y under the pressure of the control chamber 31d, the oil passage 31h between the oil inlet 31p and the first working oil port 31a is opened, and the oil passage 31g between the second working oil port 31b and the oil return port 31t is opened. The oil from the third variable pump 6 flows into the oil port 7a of the motor 7 through the oil port 6a, the first check valve 34 of the third circuit, the oil inlet 31p of the first directional valve 31 of the third circuit, the oil passage 31h, and the first working oil port 31a; the return oil from the oil port 7b of the motor 7 flows back to the oil tank 112 through the second working oil port 31b of the first directional valve 31 of the third circuit, the oil passage 31g, and the oil return port 31t. The motor 7 then rotates in the forward direction. Similarly, when the first reversing valve 31 of the third circuit is switched to the first working position X under the pressure of the control chamber 31c, the motor 7 rotates in the opposite direction.

[0049] In this operating mode, the first cylinder 8, the third cylinder 10, and the motor 7 are supplied with oil by the first variable pump 4, the second variable pump 5, and the third variable pump 6, respectively. Their working pressures do not interfere with each other, eliminating additional pressure losses caused by load differences. Simultaneously, because the motor 7 is independently supplied with oil, when operating simultaneously with the first cylinder 8 and the third cylinder 10, its working pressure can be increased under high inertia load conditions, accelerating its rotation speed and improving operating efficiency.

[0050] In the second circuit operation mode, the motor 7 and the third cylinder 10 operate independently, see... Figure 3 .

[0051] The first directional valve 11 of the first circuit switches to the first working position X under the pressure of the control chamber 11a, and the oil passage 11b between the oil inlet 11p and the oil return port 11t is closed. The second directional valve 12 of the first circuit switches to the second working position Y under the pressure of the control chamber 12d, and the oil passage 12e between the oil inlet 12p and the working oil port 12a is opened. The oil from the first variable pump 4 enters the large chamber working oil port 10a of the third cylinder 10 through the oil port 4a, the sixth check valve 111 of the first circuit, the oil inlet passage P1, the fifth check valve 110 of the first circuit, the oil inlet 12p of the second directional valve 12 of the first circuit, the oil passage 12e, and the working oil port 12a, and the third cylinder 10 extends.

[0052] The first directional valve 21 of the second circuit switches to the first working position X under the pressure of the control chamber 21a, closing the oil passage 21b between the inlet 21p and the return port 21t. When the second directional valve 22 of the second circuit switches to the first working position X under the pressure of the control chamber 22c, the oil passage 22b between the inlet 22p and the working port 22a opens. The third directional valve 23 of the second circuit switches to the second working position Y under the pressure of the control chamber 23d, opening the oil passage 23e between the working port 23b and the return port 23t. The oil from the second variable pump 5 flows into the large chamber working port 10a of the third cylinder 10 through the oil port 5a, the third check valve 27 of the second circuit, the oil inlet P2, the second check valve 26 of the second circuit, the oil inlet 22p of the second reversing valve 22 of the second circuit, the oil passage 22b, and the working oil port 22a. The oil returning from the small chamber working port 10b of the third cylinder 10 flows back into the return oil passage T through the working oil port 23b and the return oil port 23t of the third reversing valve 23 of the second circuit, and then flows back to the oil tank 112, at which point the third cylinder 10 extends.

[0053] The first directional valve 33 of the third circuit switches to the first working position X under the pressure of the control chamber 33a, and the oil passage 33b between the oil inlet 33p and the oil return port 33t is closed. When the first directional valve 31 of the third circuit switches to the second working position Y under the pressure of the control chamber 31d, the oil passage 31h between the oil inlet 31p and the first working oil port 31a is opened, and the oil passage 31g between the second working oil port 31b and the oil return port 31t is opened. The oil from the third variable pump 6 flows into the oil port 7a of the motor 7 through the oil port 6a, the first check valve 34 of the third circuit, the oil inlet 31p of the first directional valve 31 of the third circuit, the oil passage 31h, and the first working oil port 31a; the oil returning from the oil port 7b of the motor flows back to the oil tank 112 through the second working oil port 31b of the first directional valve 31 of the third circuit, the oil passage 31g, and the oil return port 31t. The motor 7 then rotates in the forward direction. Similarly, when the first reversing valve 31 of the third circuit is switched to the first working position X under the pressure of the control chamber 31c, the motor 7 rotates in the opposite direction.

[0054] At this time, the motor 7 is supplied with oil independently. When it operates simultaneously with the third cylinder 10, it can increase the working pressure of the motor 7 under the condition of large inertia load, speed up the rotation speed, and improve the operation efficiency. At the same time, the first variable pump 4 and the second variable pump 5 combine to supply oil to the third cylinder 10, which can speed up the extension speed of the third cylinder 10 and adjust the coordination of the operation.

[0055] In the 3-circuit operating mode 3, the first cylinder 8, the second cylinder 9, and the third cylinder 10 operate independently, see [link to details]. Figure 4 .

[0056] When the first reversing valve 11 of the first circuit is switched to the first working position X under the pressure of the control chamber 11a, the oil passage 11b between the oil inlet 11p and the oil return port 11t is closed. When the fifth reversing valve 15 of the first circuit is switched to the first working position X under the pressure of the control chamber 15c, the oil passage 15e between the oil inlet 15p and the first working oil port 15a is opened, and the oil passage 15f between the second working oil port 15b and the oil return port 15t is opened. Oil from the first variable pump 4 flows through port 4a, the sixth check valve 111 of the first circuit, the inlet oil line P1, the first check valve 16 of the first circuit, the inlet port 15p of the fifth directional valve 15 of the first circuit, the oil line 15e, and the first working port 15a into the working port 8a of the small chamber of the first cylinder 8. Oil returning from the working port 8b of the large chamber of the first cylinder 8 flows through the second working port 15b and the return port 15t of the fifth directional valve 15 of the first circuit into the return oil line T and then back to the oil tank 112, causing the first cylinder 8 to retract. Similarly, when the fifth directional valve 15 of the first circuit is switched to the second working position Y under the pressure of the control chamber 15d, the first cylinder 8 extends.

[0057] The first directional valve 21 of the second circuit switches to the first working position X under the pressure of the control chamber 21a, and the oil passage 21b between the oil inlet 21p and the oil return port 21t is closed. The third directional valve 23 of the second circuit switches to the second working position Y under the pressure of the control chamber 23d, and the oil passage 23e between the working oil port 23b and the oil return port 23t is opened. The fourth directional valve 24 of the second circuit switches to the first working position X under the pressure of the control chamber 24c, and the oil passage 24e between the oil inlet 24p and the first working oil port 24a is opened, and the oil passage 24f between the second working oil port 24b and the oil return port 24t is opened. Oil from the second variable pump 5 flows through port 5a, the third check valve 27 of the second circuit, the inlet oil line P2, the first check valve 25 of the second circuit, the inlet port 24p of the fourth directional valve 24 of the second circuit, the oil line 24e, and the first working port 24a into the large working port 9a of the second cylinder 9. Oil returning from the small working port 9b of the second cylinder 9 flows through the second working port 24b and the return port 24t of the fourth directional valve 24 of the second circuit into the return oil line T and then back to the oil tank 112, causing the second cylinder 9 to extend. Similarly, when the fourth directional valve 24 of the second circuit switches to the second working position Y under the pressure of the control chamber 24d, the second cylinder 9 retracts.

[0058] The third directional valve 33 of the third circuit switches to the first working position X under the pressure of the control chamber 33a, and the oil passage 33b between the oil inlet 33p and the return oil port 33t is closed. The second directional valve 32 of the third circuit switches to the first working position X under the pressure of the control chamber 32c, and the oil passage 32e between the oil inlet 32p and the first working oil port 32a is opened. The oil from the third variable pump 6 flows into the large chamber working oil port 10a of the third cylinder 10 through the oil port 6a, the second check valve 35 of the third circuit, the oil inlet 32p of the second directional valve 32 of the third circuit, the first working oil port 32a, and the working oil passage p32a. The return oil from the small chamber working oil port 10b of the third cylinder 10 flows back to the oil tank 112 through the working oil port 23b and the return oil port 23t of the third directional valve 23 of the second circuit.

[0059] At this time, the first variable pump 4 supplies oil to the first cylinder 8 and returns oil through the first circuit 1; the second variable pump 5 supplies oil to the second cylinder 9 and returns oil through the second circuit 2; the third variable pump 6 supplies oil to the third cylinder 10 and returns oil through the second circuit 2. This working mode of the circuit eliminates the rigid correspondence between the variable pumps and the valves, realizing a flexible combination of the working chambers of the variable pumps and cylinders. Meanwhile, the second directional valve 32 in the third circuit is a 3-position 2-way type. Compared with a 3-position 4-way directional valve, the hydraulic valve components have a simpler structure and lower cost.

[0060] The 4-loop operating mode 4 is built upon operating mode 3, achieving energy savings under the condition that the first cylinder 8, the second cylinder 9, and the third cylinder 10 operate independently. See [link / description]. Figure 5 .

[0061] The first directional valve 11 of the first circuit switches to the first working position X under the pressure of the control chamber 11a, closing the oil passage 11b between the inlet port 11p and the return port 11t. The second directional valve 12 of the first circuit switches to the first working position X under the pressure of the control chamber 12c, opening the oil passage 12b between the working port 12a and the return port 12t. The third directional valve 13 of the first circuit switches to the first working position X under the pressure of the control chamber 13c, opening the oil passage 13b between the inlet port 13p and the working port 13a. The fourth directional valve 14 of the first circuit switches to the second working position Y under the pressure of the control chamber 14c, opening the oil passage 14b between the inlet port 14p and the working port 14a. The fifth directional valve 15 of the first circuit is switched to the first working position X under the pressure of the control chamber 15c. The oil passage 15e between the oil inlet 15p and the first working oil port 15a is opened, and the oil passage 15f between the second working oil port 15b and the return oil port 15t is opened.

[0062] The first directional valve 21 of the second circuit switches to the first working position X under the pressure of the control chamber 21a, and the oil passage 21b between the oil inlet 21p and the oil return port 21t is closed. The second directional valve 22 of the second circuit switches to the second working position Y under the pressure of the control chamber 22d, and the oil passage 22e between the working oil port 22a and the oil return port 22t is opened. The fourth directional valve 24 of the second circuit switches to the first working position X under the pressure of the control chamber 24c, and the oil passage 24e between the oil inlet 24p and the first working oil port 24a is opened, and the oil passage 24f between the second working oil port 24b and the oil return port 24t is opened.

[0063] The third directional valve 33 of the third circuit switches to the first working position X under the pressure of the control chamber 33a, and the oil passage 33b between the oil inlet 33p and the oil return port 33t is closed. The second directional valve 32 of the third circuit switches to the second working position Y under the pressure of the control chamber 32d, and the oil passage 32f between the oil inlet 32p and the second working oil port 32b is opened.

[0064] In the first circuit 1, the oil from the first variable pump 4 flows into the small chamber working port 8a of the first cylinder 8 through the oil port 4a, the sixth check valve 111 of the first circuit, the oil inlet P1, the first check valve 16 of the first circuit, the oil inlet 15p of the fifth directional valve 15 of the first circuit, the oil passage 15e, and the first working port 15a. The oil returning from the large chamber working port 8b of the first cylinder 8 flows back through the second working port 15b of the fifth directional valve 15 of the first circuit, and then flows back into the oil tank 112 through the return port 15t. The first cylinder 8 then retracts.

[0065] In the second circuit 2, the oil from the second variable pump 5 flows into the large chamber working port 9a of the second cylinder 9 through the oil port 5a, the third check valve 27 of the second circuit, the oil inlet P2, the first check valve 25 of the second circuit, the oil inlet 24p of the fourth directional valve 24 of the second circuit, the oil passage 24e, and the first working port 24a. The oil returning from the small chamber working port 9b of the second cylinder 9 flows back into the return oil passage T through the second working port 24b and the return port 24t of the fourth directional valve 24 of the second circuit, and then flows back to the oil tank 112, causing the second cylinder 9 to extend.

[0066] In the third circuit 3, the oil from the third variable pump 6 flows into the small chamber working port 10b of the third cylinder 10 through the oil port 6a, the second check valve 35 of the third circuit, the oil inlet 32p and oil port 32b of the second reversing valve 32 of the third circuit, and the working oil passage p32b. The oil returns through the large chamber working port 10a of the third cylinder 10. It then flows back to the oil tank 112 through the working port 22a and return port 22t of the second reversing valve 22 of the second circuit, and then flows back to the oil passage T. It also flows back to the oil tank 112 through the working port 12a and return port 12t of the second reversing valve 12 of the first circuit, and then flows back to the oil passage T. The third cylinder 10 retracts. When the third cylinder 10 retracts under a large gravitational load, the return oil from the large chamber working port 10a can flow into the small chamber working port 10b of the third cylinder 10 through the inlet 14p, working port 14a, and the first circuit fourth check valve 19 of the first circuit, forming a differential circuit to increase the retraction speed of the third cylinder 10. When the pressure in the small chamber of the third cylinder 10 is lower than the pressure in the return oil circuit T, the flow rate in the return oil circuit T flows to the small chamber working port 10b of the third cylinder 10 through the second circuit fourth check valve 28 to avoid the retraction action stopping due to low pressure. When the pressure at the large working port 10a of the third cylinder 10 is higher than the pressure in the inlet oil circuit P2, the return oil from the large working port 10a can flow through the inlet port 13p and working port 13a of the third directional valve 13 in the first circuit, and then through the second check valve 17 in the first circuit into the inlet oil circuit P2. Together with the second variable pump 5, it supplies oil to the fourth directional valve 24 in the second circuit, increasing the operating speed of the second cylinder 9. When the pressure at the large working port 10a of the third cylinder 10 is higher than the pressure in the inlet oil circuit P1, the return oil from the large working port 10a can flow through the inlet port 13p and working port 13a of the third directional valve 13 in the first circuit, and then through the third check valve 18 in the first circuit into the first inlet oil circuit P1. Together with the first variable pump 5, it supplies oil to the fifth directional valve 15 in the first circuit, increasing the operating speed of the first cylinder 8. By adjusting the pressure of the control chamber 12c of the second reversing valve 12 in the first circuit and the pressure of the control chamber 12c of the second reversing valve 22 in the second circuit, the flow area of ​​the oil circuit 12b and the oil circuit 22e can be continuously controlled, thereby adjusting the flow rate from the working oil port 10a of the large chamber of the third oil cylinder 10 to the oil inlet P1 and the oil inlet P2.

[0067] At this time, when the third cylinder 10 retracts under a large gravitational load, it effectively utilizes gravitational potential energy, increases the operating speed of the first cylinder 8 and the second cylinder 9, and thus improves the working efficiency of the equipment.

[0068] Operating mode 5 of the 5-circuit is above operating mode 4. When the third cylinder 10 retracts under a large gravitational load, and the return oil pressure at the large working port 10a of the third cylinder 10 is higher than the working pressure of the first cylinder 8 and the second cylinder 9, and at the same time the first cylinder 8 and the second cylinder 9 move slightly, see Appendix. Figure 6 .

[0069] In the first circuit 1, the oil from the first variable pump 4 flows through its outlet 4a, the inlet 11p, the oil passage 11b, and the return port 11t of the first reversing valve 11 of the first circuit into the return oil passage T and then back to the oil tank 112. The first variable pump 4 is on standby at low pressure.

[0070] In the second circuit 2, the oil from the second variable pump 5 flows through its outlet 5a, the inlet 21p of the first directional valve 21 of the second circuit, the oil passage 21b, and the return port 21t into the return oil passage T and then flows back to the oil tank 112. The second variable pump 5 is on standby at low pressure.

[0071] In the third circuit 3, the oil from the third variable pump 6 flows into the small chamber working port 10b of the third cylinder 10 through the oil port 6a, the second check valve 35 of the third circuit, the oil inlet 32p of the second reversing valve 32 of the third circuit, the second working oil port 32b, and the working oil path p32b. The oil returns from the large chamber working port 10a of the third cylinder 10, flows into the return oil path T through the working oil port 22a and the return oil port 22t of the second reversing valve 22 of the second circuit, and then flows back to the oil tank 112. It also flows into the return oil path T through the working oil port 12a and the return oil port 12t of the second reversing valve 12 of the first circuit, and then flows back to the oil tank 112. The third cylinder 10 retracts. Oil returning from the large working port 10a of the third cylinder 10 can flow into the small working port 10b of the third cylinder 10 through the inlet 14p and working port 14a of the fourth directional valve 14 in the first circuit, and the fourth check valve 19 in the first circuit, forming a differential circuit to increase the retraction speed of the third cylinder 10. When the pressure in the small chamber of the third cylinder 10 is lower than the pressure in the return oil circuit T, the flow rate in the return oil circuit T flows to the small working port 10b of the third cylinder 10 through the fourth check valve 28 in the second circuit to avoid the retraction action stopping due to low pressure. At this time, oil returning from the large working port 10a of the third cylinder 10 can flow into the second inlet oil circuit P2 through the inlet 13p and working port 13a of the third directional valve 13 in the first circuit, and through the second check valve 17 in the first circuit, driving the second cylinder 9 to move. Simultaneously, the return oil from the large working port 10a of the third cylinder 10 can flow into the first inlet oil circuit P1 through the first circuit third check valve 18 via ports 13p and 13a of the first circuit third directional valve 13, thus driving the first cylinder 8 to move. By adjusting the pressure of the control chamber 12c of the first circuit second directional valve 12 and the control chamber 12c of the second circuit second directional valve 22, the flow area of ​​oil circuits 12b and 22e can be continuously controlled, thereby adjusting the flow rate from the large working port 10a of the third cylinder 10 to the inlet oil circuits P1 and P2. Furthermore, when the pressure of the small working port 10b of the third cylinder 10 is higher than the return oil pressure of the large working port 10a, the first circuit fourth directional valve 14 is in the first working position X, cutting off the connection between the working port 14b and the working port 14a, and canceling the differential circuit oil replenishment function.

[0072] 6-loop operating mode 6 is used to realize the independent operation of motor 7, third cylinder 10, and first cylinder 8, as well as the recovery and utilization of gravitational potential energy. See [link / description]. Figure 7 .

[0073] When the fourth directional valve 24 of the second circuit is in the third working position N and the second cylinder 9 is not in motion, in the second circuit 2, the oil from the second variable pump 5 flows into the small chamber working port 10b of the third cylinder 10 through its outlet 5a, the third check valve 27 of the second circuit, the second inlet oil line P2, the second check valve 26 of the second circuit, the inlet 23p of the third directional valve 23 of the second circuit, the oil line 23a, and the working port 23b; the oil returning from the large chamber working port 10a of the third cylinder 10 flows into the return oil line T through the working port 22a and the return oil line 22t of the second directional valve 22 of the second circuit and then flows back to the oil tank 112. It also flows into the return oil line T through the working port 12a and the return oil line 12t of the second directional valve 12 of the first circuit and then flows back to the oil tank 112, and the third cylinder 10 retracts. Oil returning from the large working port 10a of the third cylinder 10 can flow into the small working port 10b of the third cylinder 10 through the inlet 14p and working port 14a of the fourth directional valve 14 in the first circuit, and the fourth check valve 19 in the first circuit, forming a differential circuit to increase the retraction speed of the third cylinder 10. When the pressure at the small working port 10b of the third cylinder 10 is lower than the pressure in the return oil circuit T, the flow rate in the return oil circuit T flows to the small working port 10b of the third cylinder 10 through the fourth check valve 28 in the second circuit to avoid the retraction action stopping due to low pressure. At this time, oil returning from the large working port 10a of the third cylinder 10 can flow into the second inlet oil circuit P2 through the inlet 13p and working port 13a of the third directional valve 13 in the first circuit, and then through the second check valve 17 in the first circuit, merging with the inlet oil of the second variable pump 5, and flowing to the small working port 10b of the third cylinder 10, causing the third cylinder 10 to retract. When the pressure at port 5a of the second variable pump 5 is higher than the pressure at the working port 10a of the large chamber of the third cylinder 10, the second variable pump 5 supplies oil to the third cylinder 10. When the pressure at port 5a of the second variable pump 5 is lower than the pressure at the working port 10a of the large chamber of the third cylinder 10, the first directional valve 21 of the second circuit can be controlled to the working position Z, and the second variable pump 5 is unloaded at low pressure to reduce losses and improve the potential energy utilization rate of the third cylinder 10. At the same time, the return oil from the working port 10a of the large chamber of the third cylinder 10 can flow into the first oil inlet circuit P1 through the inlet port 13p and working port 13a of the third directional valve 13 of the first circuit, and through the third check valve 18 of the first circuit, thus driving the first cylinder 8 to move. By adjusting the pressure of the control chamber 12c of the first circuit second reversing valve 12 and the control chamber 12c of the second circuit second reversing valve 22, the flow area of ​​oil circuit 12b and oil circuit 22e can be continuously controlled, thereby adjusting the flow rate from the working oil port 10a of the large chamber of the third oil cylinder 10 to the oil inlet P1 and oil inlet P2.

[0074] At this time, the oil from port 6a of the third variable pump 6 flows into the return oil circuit T through the inlet 33p and return port 33t of the third directional valve 33 in the third circuit, and then flows back to the oil tank 112. When the motor 7 needs to be activated, the third directional valve 33 in the third circuit switches to the first working position X to close the low-pressure return oil circuit, and the first directional valve 31 in the third circuit switches to the first working position X or the second working position Y to drive the motor 7 to rotate in the forward or reverse direction. The oil from the second variable pump 4 can flow into the return oil circuit T through the first directional valve 11 in the first circuit and then flow back to the oil tank 112, or it can flow into the first directional valve 15 in the first circuit through the sixth check valve 111 in the first circuit and the return oil from the third cylinder 10 through the third check valve 18 in the first circuit to supply oil, thereby driving the first cylinder 8 to move.

[0075] In this operating mode, motor 7, first cylinder 8, and third cylinder 10 operate independently, eliminating throttling losses caused by pressure differences between actions. Rotary motor 7 meets high-torque starting conditions under heavy loads, resulting in faster acceleration. The return oil flow from third cylinder 10 can flow to both first cylinder 8 and third cylinder 10, leading to higher potential energy utilization.

[0076] In one specific embodiment of the present invention, when the first variable pump 4 supplies oil to the first cylinder 8 and the third cylinder 10, the first reversing valve 11 of the first circuit, under the pressure of the control chamber 11a, reverses from working position Z through the second working position Y to the first working position X, and the oil passage 11b gradually closes to regulate the flow rate to each cylinder. Similarly, when the second variable pump 5 supplies oil to the second cylinder 9 and the third cylinder 10, the first reversing valve 11 of the second circuit, under the pressure of the control chamber 21a, reverses from working position Z through the second working position Y to the first working position X, and the oil passage 21b gradually closes to regulate the flow rate to each cylinder. When the third variable pump 6 supplies oil to the motor 7 and the third cylinder 10, the third reversing valve 33 of the third circuit, under the pressure of the control chamber 33a, reverses from working position Z through the second working position Y to the first working position X, and the oil passage 33b gradually closes to regulate the flow rate to each cylinder.

[0077] In one specific embodiment of the present invention, when it is necessary to increase the extension speed of the third cylinder 10, the first variable pump 4 supplies oil to the third cylinder 10 through the first circuit second reversing valve 12, the second variable pump 5 through the second circuit second reversing valve 12, and the third variable pump 6 through the third circuit second reversing valve 32.

[0078] In one specific embodiment of the present invention, when it is necessary to adjust the ratio between the speed of the motor 7 and the extension / retraction speed of the third cylinder 10, the flow of the third variable pump 6 can be diverted to the third cylinder 10 by switching the second reversing valve 32 of the third circuit to the first working position X or the second working position Y respectively.

[0079] In one specific embodiment of the present invention, when the speed ratio between the first cylinder 8 and the third cylinder 10 or the second cylinder 9 and the third cylinder 10 needs to be further adjusted, the flow area of ​​the oil circuit can be reduced or increased by continuously adjusting the stroke of each reversing valve in the first circuit 1, the second circuit 2, and the third circuit 3, thereby realizing the adjustment of the flow distribution relationship between the first variable pump 4 and the second variable pump 5.

[0080] In one specific embodiment of the present invention, pressure sensors can be installed on the oil outlet 4a of the first variable pump 4, the oil outlet 5a of the second variable pump 5, the oil outlet 6a of the third variable pump 6, the first oil outlet 7a and the second oil outlet 7b of the motor 7, the oil outlets of the first cylinder 8 (small chamber working oil outlet 8a and large chamber working oil outlet 8b), the large chamber working oil outlet 9a and the small chamber working oil outlet 9b of the second cylinder 9, and the large chamber working oil outlet 10a and the small chamber working oil outlet 10b of the third cylinder 10 to coordinate the stroke of each directional valve in the first circuit 1, the second circuit 2, and the third circuit 3.

[0081] Based on the above analysis, it can be seen that in this embodiment of the invention, multiple hydraulic pumps, cylinders, motors, and a 3-position 3-way directional valve are combined through circuit design. By adopting independent control of the oil inlet and outlet of each working chamber, the problems of rigid connection between pumps and working devices, poor circuit flexibility, high coupling pressure loss due to simultaneous operation of multiple working devices, and low overall machine efficiency in conventional 2-pump 2-circuit hydraulic systems are eliminated. This allows for independent control of four tooling devices under the main operating conditions of the machine, reducing coupling losses, improving circuit flexibility, and thus enhancing the overall machine efficiency.

[0082] In this embodiment of the invention, the independent rotation of the motor 7 is controlled by a third variable pump 6, which solves the coordination problem caused by the mismatch between the rotational inertial load and the positive and negative loads of the hydraulic cylinder in a parallel throttling system. Especially under heavy load conditions, when the rotational inertia is large, the pressure of the rotary motor is limited by the working pressure of the hydraulic cylinder, resulting in low starting torque, slow acceleration, and limiting the overall operating efficiency of the machine.

[0083] In this embodiment of the invention, the oil inlet and return throttling port areas of the working chamber of the hydraulic cylinder are independently controlled, which further eliminates the problem of excessive oil inlet pressure loss or excessive return back pressure under certain working conditions, improves control flexibility, and reduces system losses.

[0084] In this embodiment of the invention, the second directional valve 32 of the third circuit 3, which performs the function of confluence of the oil cylinder, adopts a 3-position 3-way form, which is simpler than the conventional 3-position 4-way control circuit and has a lower cost for multi-pump multi-actuator circuit hydraulic valves.

[0085] In this embodiment of the invention, the third cylinder 10 retracts under the influence of external gravitational potential energy. The flow rate of the oil returning from the working port 10a flows back to the working port 10b of the third cylinder 10 through the fourth reversing valve 14 and the fourth reversing valve 19 of the first circuit, increasing the retraction speed of the third cylinder 10 while preventing a vacuum in the small cavity caused by excessively fast retraction. To further prevent the occurrence of vacuum, the oil in the return oil circuit T can flow to the working port 10a of the third cylinder 10 through the fourth check valve 28 of the second circuit. At this time, the second variable pump 5 can also further replenish the oil to the working port 10a of the third cylinder 10 at a lower pressure, thus balancing the improvement of the utilization rate of the return oil flow rate of the third cylinder 10 under the influence of gravitational potential energy and the elimination of the problem of vacuum in the small cavity caused by the rapid descent of the cylinder.

[0086] In summary, this invention provides a multi-pump, multi-actuator circuit and control method, which improves the overall energy efficiency and coordination of mobile machinery, especially earthmoving machinery, while reducing the cost of supporting valve components.

[0087] 1) 3 pumps and 3 circuits: A hydraulic system consisting of 3 hydraulic pumps (first variable pump, second variable pump and third variable pump) and 3 corresponding circuits. The 3 circuits are connected in parallel to supply oil, which can realize the flow of oil without interference between them.

[0088] 2) Independent inlet and outlet oil of dual spool valves: The inlet and outlet oil of each working chamber of hydraulic cylinders (first cylinder, second cylinder and third cylinder), motor and other actuators are controlled by one directional valve respectively; for example, the two working chambers of a piston hydraulic cylinder are controlled by two directional valves respectively for their inlet and outlet oil.

[0089] 3) The hydraulic circuit is composed of various variable pumps and motors. The variable pumps draw oil from the oil tank, and the return oil from the motors flows back to the oil tank. There are no other working devices diverting the flow in the circuit of the variable pumps and motors.

[0090] 4) Potential energy differential regeneration: When the hydraulic cylinders (first cylinder, second cylinder and third cylinder) fall under the action of gravity, part of the return oil flow is led to the oil inlet side of the cylinder through the hydraulic differential circuit, so as to realize the recovery and utilization of gravitational potential energy.

[0091] 5) Multi-circuit regeneration: When the hydraulic cylinders (first cylinder, second cylinder and third cylinder) fall under the action of gravity, the return oil flow is led to the first oil inlet P1 and the second oil inlet P2 of multiple circuits. As an auxiliary power oil source, it merges with the flow of the corresponding variable pump and supplies oil to the parallel working devices in the circuit (i.e. motor 7, first cylinder 8, second cylinder 9 and third cylinder 10), thereby improving the utilization rate of gravitational potential energy.

[0092] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only used to facilitate the description of the present invention and to simplify the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of the present invention.

[0093] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A multi-pump, multi-actuator circuit, characterized in that, include: First circuit (1), second circuit (2), third circuit (3), first variable pump (4), second variable pump (5), third variable pump (6), motor (7), first cylinder (8), second cylinder (9), third cylinder (10) and return oil circuit (T); The first variable pump (4) is connected to the oil inlet of the first circuit (1), the oil outlet of the first circuit (1) is connected to the first oil cylinder (8), and is connected to the second oil cylinder (9) and the third oil cylinder (10) respectively through the second circuit (2); The second variable pump (5) is connected to the oil inlet of the second circuit (2), and the oil outlet of the second circuit (2) is connected to the second oil cylinder (9) and the third oil cylinder (10) respectively; The third variable pump (6) is connected to the oil inlet of the third circuit (3); the oil outlet of the third circuit (3) is connected to the motor (7) and connected to the third cylinder (10) through the second circuit (2); The return oil circuit (T) is connected to the return oil ports of the first circuit (1), the second circuit (2), and the third circuit (3), respectively.

2. The multi-pump multi-actuator circuit according to claim 1, characterized in that: The first circuit (1) includes a first circuit first directional valve (11), a first circuit second directional valve (12), a first circuit third directional valve (13), a first circuit fourth directional valve (14), a first circuit fifth directional valve (15), a first circuit first check valve (16), a first circuit second check valve (17), a first circuit third check valve (18), a first circuit fourth check valve (19), a first circuit fifth check valve (110), a first circuit sixth check valve (111), and a first oil inlet circuit (P1). The second circuit (2) includes a second circuit first directional valve (21), a second circuit second directional valve (22), a second circuit third directional valve (23), a second circuit fourth directional valve (24), a second circuit first check valve (25), a second circuit second check valve (26), a second circuit third check valve (27), a second circuit fourth check valve (28), and a second oil inlet circuit (P2). The third circuit (3) includes a third circuit first reversing valve (31), a third circuit second reversing valve (32), a third circuit third reversing valve (33), a third circuit first check valve (34), a third circuit second check valve (35), a third oil inlet circuit (P3), a first oil supply circuit (P32a), and a second oil supply circuit (P32b). The first variable pump (4) is connected via its outlet (4a) to the inlet (11p) of the first circuit first directional valve (11) and the sixth check valve (111) of the first circuit, respectively; the sixth check valve (111) of the first circuit is connected via the first inlet oil passage (P1) to the first check valve (16), the third check valve (18), and the fifth check valve (110) of the first circuit; the return port (11t) of the first circuit first directional valve (11) is connected to the return oil passage (T); the inlet (12p) of the first circuit second directional valve (12) is connected to the fifth check valve (110) of the first circuit, and its return port (12p) is connected to the return oil passage (T). t) is connected to the return oil circuit (T); the working oil port (12a) of the first circuit second reversing valve (12) is connected to the oil inlet (13p) of the first circuit third reversing valve (13), the oil inlet (14p) of the first circuit fourth reversing valve (14), the working oil port (22a) of the second circuit second reversing valve (22), and the large chamber working oil port (10a) of the third cylinder (10). The working oil port (12a) of the first circuit second reversing valve (12) is also connected to the first working oil port (32a) of the third circuit second reversing valve (32) via the first oil supply circuit (P32a); the working oil port (12a) of the first circuit third reversing valve (13) is connected to the return oil circuit (T); the working oil port (12a) of the first circuit third reversing valve (13) is connected to the return oil circuit (T); the working oil port (12a) of the first circuit second reversing valve (12 ... Port (13a) is connected to the third check valve (18) of the first circuit, and is connected to the first oil inlet circuit (P1) through the third check valve (18); at the same time, the working port (13a) of the third directional valve (13) of the first circuit is also connected to the second check valve (17) of the first circuit, and is connected to the second oil inlet circuit (P2) through the second check valve (17); the working port (14a) of the fourth directional valve (14) of the first circuit is connected to the fourth check valve (19) of the first circuit, and is connected to the working port (23b) of the third directional valve (23) of the second circuit, and the second circuit The fourth check valve (28) is connected to the small chamber working port (10b) of the third cylinder (10); the fourth check valve (19) of the first circuit is connected to the second working port (32b) of the second reversing valve (32) of the third circuit via the second oil supply line (P32b); the oil inlet (15p) of the fifth reversing valve (15) of the first circuit is connected to the first check valve (16) of the first circuit, its return port (15t) is connected to the return line (T), its first working port (15a) is connected to the small chamber inlet (8a) of the first cylinder (8), and its second working port (15b) is connected to the large chamber working port (8b) of the first cylinder (8); The second variable pump (5) is connected via its outlet (5a) to the inlet (21p) of the first directional valve (21) of the second circuit and the third check valve (27) of the second circuit; the third check valve (27) of the second circuit is connected via the second inlet oil passage (P2) to the first check valve (25) of the second circuit and the second check valve (26) of the second circuit; the fourth check valve (28) of the second circuit is also connected to the return oil passage (T); the return oil port (21t) of the first directional valve (21) of the second circuit is connected to the return oil passage (T); the inlet (22p) of the second directional valve (22) of the second circuit is connected to the second check valve (27) of the second circuit. 6) The oil inlet (23p) of the third directional valve (23) of the second circuit is connected, and its return port (22t) is connected to the return oil circuit (T); the oil inlet (23t) of the third directional valve (23) of the second circuit is connected to the return oil circuit (T); the oil inlet (24p) of the fourth directional valve (24) of the second circuit is connected to the first check valve (25) of the second circuit, and its return port (24t) is connected to the return oil circuit (T); its first working oil port (24a) is connected to the large chamber working oil port (9a) of the second cylinder (9), and its second working oil port (24b) is connected to the small chamber working oil port (9b) of the second cylinder (9); The third variable pump (6) is connected to the third circuit third directional valve (33), the third circuit first check valve (34), and the third circuit second check valve (35) through its outlet (6a) and the third inlet oil passage (P3). The inlet (31p) of the third circuit first directional valve (31) is connected to the third circuit first check valve (34), its return port (31t) is connected to the return oil passage (T), its first working port (31a) is connected to the first oil port (7a) of the motor (7), and its second working port (31b) is connected to the second oil port (7b) of the motor (7). The inlet (32p) of the third circuit second directional valve (32) is connected to the third circuit second check valve (35). The return port (33t) of the third circuit third directional valve (33) is connected to the return oil passage (T).

3. A multi-pump multi-actuator circuit according to claim 2, characterized in that: The first reversing valve (11) of the first circuit is switched to the first working position (X) under the pressure of its control chamber (11a), and the oil passage (11b) between its inlet (11p) and return (11t) is closed; the fifth reversing valve (15) of the first circuit is switched to the first working position (X) under the pressure of its control chamber (15c), and the oil passage (15e) between its inlet (15p) and first working oil port (15a) is opened, and the oil passage (15f) between its second working oil port (15b) and return (15t) is opened; the oil of the first variable pump (4) passes through its outlet (4a), the sixth check valve (111) of the first circuit, the first inlet oil passage (P1), and the first... The oil inlet (15p) and oil passage (15e) of the first circuit first check valve (16) and the first circuit fifth directional valve (15) flow into the small chamber inlet (8a) of the first cylinder (8); the oil return from the large chamber working port (8b) of the first cylinder (8) flows into the return oil passage (T) through the second working port (15b) and return port (15t) of the first circuit fifth directional valve (15), and then flows back to the oil tank (112), and the first cylinder (8) retracts; similarly, when the first circuit fifth directional valve (15) is switched to the second working position (Y) under the pressure of its control chamber (15d), the first cylinder (8) extends; When the first directional valve (21) of the second circuit is switched to the first working position (X) under the pressure of its control chamber (21a), the oil passage (21b) between its oil inlet (21p) and oil return port (21t) is closed; when the second directional valve (22) of the second circuit is switched to the first working position (X) under the pressure of its control chamber (22c), the oil passage (22b) between its oil inlet (22p) and working oil port (22a) is opened; The second circuit third directional valve (23) switches to the second working position (Y) under the pressure of its control chamber (23d), and the oil passage (23e) between its working port (23b) and return port (23t) is opened; the oil from the second variable pump (5) passes through its outlet (5a), the second circuit third check valve (27), the second inlet oil passage (P2), the second circuit second check valve (26), the inlet (22p) of the second circuit second directional valve (22), the oil passage (22b), and the working port (22a) of the second circuit second directional valve (22). Oil flows into the large working port (10a) of the third cylinder (10); the oil returning from the small working port (10b) of the third cylinder (10) flows into the return oil circuit (T) through the working port (23b) and return port (23t) of the third reversing valve (23) of the second circuit, and then flows back to the oil tank (112), and the third cylinder (10) extends; similarly, when the second reversing valve (22) of the second circuit is reversed to the second working position (Y) under the pressure of its control chamber (22d), the oil circuit (22e) between its working port (22a) and return port (22t) is opened; The second circuit third directional valve (23) is switched to the first working position (X) under the pressure of its control chamber (23c), and the oil passage (23a) between its inlet (23p) and working oil port (23b) is opened; the oil from the second variable pump (5) flows into the small working oil port (10b) of the third cylinder (10) through the oil port (5a), the second circuit third check valve (27), the oil inlet passage (P2), the second circuit second check valve (26), the oil inlet (23p), the oil passage (23a), and the working oil port (23b) of the second circuit third directional valve (23); the oil from the large working oil port (10a) of the third cylinder (10) flows back into the oil return passage (T) through the working oil port (22a) and the return oil port (22t) of the second circuit second directional valve (22), and then flows back to the oil tank (112), and the third cylinder (10) retracts; The third reversing valve (33) of the third circuit switches to the first working position (X) under the pressure of its control chamber (33a), and the oil passage (33b) between its inlet (33p) and return port (33t) is closed; when the first reversing valve (31) of the third circuit switches to the second working position (Y) under the pressure of its control chamber (31d), the oil passage (31h) between its inlet (31p) and the first working oil port (31a) is opened, and the oil passage (31g) between its second working oil port (31b) and return port (31t) is opened; the oil from the third variable pump (6) flows through its outlet (6a) and the first one-way valve of the third circuit. The oil inlet (31p), oil passage (31h), and first working oil port (31a) of valve (34), the first reversing valve (31) of the third circuit flow into the first oil port (7a) of motor (7); the oil return from the second oil port (7b) of motor (7) flows back to the oil tank (112) after passing through the second working oil port (31b), oil passage (31g), and return oil port (31t) of the first reversing valve (31) of the third circuit and the oil passage (31g). Similarly, when the first reversing valve (31) of the third circuit is reversed to the second working position (X) under the pressure of its control chamber (31c), motor (7) rotates in the opposite direction.

4. A multi-pump multi-actuator circuit according to claim 2, characterized in that: The first reversing valve (11) of the first circuit is switched to the first working position (X) under the pressure of its control chamber (11a), and the oil passage (11b) between its oil inlet (11p) and oil return port (11t) is closed; the second reversing valve (12) of the first circuit is switched to the second working position (Y) under the pressure of its control chamber (12d), and the oil passage (12e) between its oil inlet (12p) and working oil port (12a) is opened; the oil of the first variable pump (4) enters the large chamber working oil port (10a) of the third cylinder (10) through the oil port (4a), the sixth check valve (111) of the first circuit, the first oil inlet oil passage (P1), the fifth check valve (110) of the first circuit, the oil inlet (12p) and oil passage (12e) of the second reversing valve (12) of the first circuit, the oil passage (12a) of the second reversing valve (12) of the first circuit, and the third cylinder (10) extends; When the first directional valve (21) of the second circuit is switched to the first working position (X) under the pressure of its control chamber (21a), the oil passage (21b) between the oil inlet (21p) and the oil return port (21t) is closed; when the second directional valve (22) of the second circuit is switched to the first working position (X) under the pressure of its control chamber (22c), the oil passage (22b) between its oil inlet (22p) and the working oil port (22a) is opened; The second circuit third directional valve (23) is switched to the second working position (Y) under the pressure of its control chamber (23d), and the oil passage (23e) between its working port (23b) and return port (23t) is opened; the oil of the second variable pump (5) flows into the large working port (10a) of the third cylinder (10) through its outlet (5a), the second circuit third check valve (27), the second inlet oil passage (P2), the second circuit second check valve (26), the inlet port (22p) of the second circuit second directional valve (22), the oil passage (22b), and the working port (22a); the return oil of the small working port (10b) of the third cylinder (10) flows into the return oil passage (T) through the working port (23b) and return port (23t) of the second circuit third directional valve (23), and then flows back to the oil tank (112), and the third cylinder (10) extends; The first directional valve (33) of the third circuit switches to the first working position (X) under the pressure of its control chamber (33a), and the oil passage (33b) between its inlet (33p) and return port (33t) is closed; when the first directional valve (31) of the third circuit switches to the second working position (Y) under the pressure of its control chamber (31d), the oil passage (31h) between its inlet (31p) and the first working oil port (31a) is opened, and the oil passage (31g) between its second working oil port (31b) and return port (31t) is opened; the oil of the third variable pump (6) flows through its outlet (6a) and the first single-phase pump of the third circuit. The oil inlet (31p), oil passage (31h), and first working oil port (31a) of the first directional valve (34) of the third circuit flow into the first oil port (7a) of the motor (7); the oil returned from the second oil port (7b) of the motor (7) flows back into the oil return passage (T) through the second working oil port (31b), oil passage (31g), and return oil port (31t) of the first directional valve (31) of the third circuit and then flows back into the oil tank (112), and the motor (7) rotates in the forward direction; similarly, when the first directional valve (31) of the third circuit is switched to the first working position (X) under the pressure of its control chamber (31c), the motor (7) rotates in the reverse direction.

5. A multi-pump multi-actuator circuit according to claim 2, characterized in that: The first reversing valve (11) of the first circuit switches to the first working position (X) under the pressure of its control chamber (11a), and the oil passage (11b) between its inlet (11p) and return (11t) is closed; when the fifth reversing valve (15) of the first circuit switches to the first working position (X) under the pressure of its control chamber (15c), the oil passage (15e) between its inlet (15p) and first working oil port (15a) is opened, and the oil passage (15f) between its second working oil port (15b) and return (15t) is opened; the oil of the first variable pump (4) passes through its outlet (4a), the sixth check valve (111) of the first circuit, and the first inlet oil passage. (P1), the first one-way valve (16) of the first circuit and the oil inlet (15p), oil passage (15e) and first working oil port (15a) of the fifth directional valve (15) of the first circuit flow into the small working oil port (8a) of the first cylinder (8); the oil return from the large working oil port (8b) of the first cylinder (8) flows into the return oil passage (T) through the second working oil port (15b) and return oil port (15t) of the fifth directional valve (15) of the first circuit and then flows back to the oil tank (112), and the first cylinder (8) retracts; similarly, when the fifth directional valve (15) of the first circuit is switched to the second working position (Y) under the pressure of its control chamber (15d), the first cylinder (8) extends; The first directional valve (21) of the second circuit is switched to the first working position (X) under the pressure of its control chamber (21a), and the oil passage (21b) between its inlet (21p) and return (21t) is closed; the third directional valve (23) of the second circuit is switched to the second working position (Y) under the pressure of its control chamber (23d), and the oil passage (23e) between its working oil port (23b) and return (23t) is opened; The second circuit fourth directional valve (24) is switched to the first working position (X) under the pressure of its control chamber (24c). The oil passage (24e) between its inlet (24p) and the first working oil port (24a) is opened, and the oil passage (24f) between its second working oil port (24b) and the return oil port (24t) is opened. The oil from the second variable pump (5) passes through the oil port (5a), the second circuit third check valve (27), the second oil inlet passage (P2), the second circuit first check valve (25), and the oil inlet (24t) of the second circuit fourth directional valve (24). 4p), oil passage (24e), first working oil port (24a) flow into the large working oil port (9a) of the second oil cylinder (9); the small working oil port (9b) of the second oil cylinder (9) returns oil through the second working oil port (24b) and return oil port (24t) of the fourth directional valve (24) of the second circuit and flows back to the oil tank (112) after flowing into the return oil passage (T), and the second oil cylinder (9) extends; similarly, when the fourth directional valve (24) of the second circuit is switched to the second working position (Y) under the pressure of its control chamber (24d), the second oil cylinder (9) retracts; The third reversing valve (33) of the third circuit switches to the first working position (X) under the pressure of its control chamber (33a), and the oil passage (33b) between its inlet (33p) and return port (33t) is closed; the second reversing valve (32) of the third circuit switches to the first working position (X) under the pressure of its control chamber (32c), and the oil passage (32e) between its inlet (32p) and first working port (32a) is opened; the oil from the third variable pump (6) flows through its outlet. (6a) The oil inlet (32p), first working oil port (32a), and working oil passage (p32a) of the second check valve (35) and the second directional valve (32) of the third circuit flow into the large working oil port (10a) of the third cylinder (10); the oil return from the small working oil port (10b) of the third cylinder (10) flows into the return oil passage (T) through the working oil port (23b) and return oil port (23t) of the third directional valve (23) of the second circuit and then flows back to the oil tank (112).

6. A multi-pump multi-actuator circuit according to claim 5, characterized in that: When the first reversing valve (11) of the first circuit switches to the first working position (X) under the pressure of its control chamber (11a), the oil passage (11b) between its inlet (11p) and return port (11t) is closed; when the second reversing valve (12) of the first circuit switches to the first working position (X) under the pressure of its control chamber (12c), the oil passage (12b) between its working port (12a) and return port (12t) is opened; when the third reversing valve (13) of the first circuit switches to the first working position (X) under the pressure of its control chamber (13c), the oil passage (13b) between its inlet (13p) and working port (13a) is opened; when the fourth reversing valve (14) of the first circuit switches to the second working position (Y) under the pressure of its control chamber (14c), the oil passage (11b) between its inlet (14p) and working port (11t) is opened. The oil passage (14b) between the oil ports (14a) is opened; the fifth directional valve (15) of the first circuit is switched to the first working position (X) under the pressure of its control chamber (15c), the oil passage (15e) between its inlet (15p) and the first working oil port (15a) is opened, and the oil passage (15f) between its second working oil port (15b) and the return oil port (15t) is opened; the first directional valve (21) of the second circuit is switched to the first working position (X) under the pressure of its control chamber (21a), and the oil passage (21b) between its inlet (21p) and the return oil port (21t) is closed; the second directional valve (22) of the second circuit is switched to the second working position (Y) under the pressure of its control chamber (22d), and the oil passage (22e) between its working oil port (22a) and the return oil port (22t) is opened; The fourth directional valve (24) of the second circuit switches to the first working position (X) under the pressure of its control chamber (24c), and the oil passage (24e) between its inlet (24p) and the first working oil port (24a) is opened, and the oil passage (24f) between its second working oil port (24b) and the return oil port (24t) is opened; the third directional valve (33) of the third circuit switches to the first working position (X) under the pressure of its control chamber (33a), and the oil passage (33b) between its inlet (33p) and the return oil port (33t) is closed; the second directional valve (32) of the third circuit switches to the second working position (Y) under the pressure of its control chamber (32d), and the oil passage (32f) between its inlet (32p) and the second working oil port (32b) is opened; In the first circuit (1), the oil from the first variable pump (4) flows into the small working port (8a) of the first cylinder (8) through its outlet (4a), the sixth check valve (111) of the first circuit, the first oil inlet (P1), the first check valve (16) of the first circuit, the oil inlet (15p) of the fifth directional valve (15) of the first circuit, the oil passage (15e), and the first working port (15a); the oil from the large working port (8b) of the first cylinder (8) returns through the second working port (15b) of the fifth directional valve (15) of the first circuit, and flows back to the oil tank (112) after flowing into the return oil passage (T) through the return port (15t), and the first cylinder (8) retracts. In the second circuit (2), the oil from the second variable pump (5) flows into the large working port (9a) of the second cylinder (9) through its outlet (5a), the third check valve (27) of the second circuit, the second inlet oil passage (P2), the first check valve (25) of the second circuit, the inlet (24p) of the fourth directional valve (24) of the second circuit, the oil passage (24e), and the first working port (24a); the oil from the small working port (9b) of the second cylinder (9) flows back into the return oil passage (T) through the second working port (24b) and the return oil port (24t) of the fourth directional valve (24) of the second circuit, and then flows back to the oil tank (112), and the second cylinder (9) extends. In the third circuit (3), the oil from the third variable pump (6) flows into the small working port (10b) of the third cylinder (10) through its outlet (6a), the second check valve (35) of the third circuit, the inlet (32p) of the second reversing valve (32) of the third circuit, the second working port (32b), and the working oil passage (p32b); the oil from the large working port (10a) of the third cylinder (10) returns through the working port (22a) and return port (22t) of the second reversing valve (22) of the second circuit, flows into the return oil passage (T) and then back to the oil tank (112), and flows into the return oil passage (T) and then back to the oil tank (112) through the working port (12a) and return port (12t) of the second reversing valve (12) of the first circuit, and the third cylinder (10) retracts; When the third cylinder (10) retracts under a large gravitational load, the return oil from the large working port (10a) of the third cylinder (10) flows into the small working port (10b) of the third cylinder (10) through the inlet (14p), working port (14a) of the fourth directional valve (14) of the first circuit, and the fourth check valve (19) of the first circuit, forming a differential circuit and increasing the retraction speed of the third cylinder (10). When the pressure at the working port (10b) of the small chamber of the third cylinder (10) is lower than the pressure at the return oil circuit (T), the flow rate at the return oil circuit (T) flows through the fourth check valve (28) of the second circuit to the working port (10b) of the small chamber of the third cylinder (10) to avoid the retraction action from stopping due to low pressure. When the pressure of the working port (10a) of the large chamber of the third cylinder (10) is higher than the pressure of the second oil inlet circuit (P2), the oil returning from the working port (10a) of the large chamber of the third cylinder (10) passes through the oil inlet (13p) and working port (13a) of the third directional valve (13) of the first circuit, and then flows into the second oil inlet circuit (P2) through the second check valve (17) of the first circuit. Together with the second variable pump (5), it supplies oil to the fourth directional valve (24) of the second circuit, thereby increasing the action speed of the second cylinder (9). When the pressure at the working port (10a) of the large chamber of the third cylinder (10) is higher than the pressure at the first oil inlet circuit (P1), the return oil from the working port (10a) of the large chamber of the third cylinder (10) flows into the first oil inlet circuit (P1) through the oil inlet (13p), working port (13a) of the third directional valve (13) of the first circuit, and the third check valve (18) of the first circuit. Together with the first variable pump (5), it supplies oil to the fifth directional valve (15) of the first circuit, thereby increasing the operating speed of the first cylinder (8). By adjusting the pressure of the control chamber (12c) of the second reversing valve (12) of the first circuit and the pressure of the control chamber (12c) of the second reversing valve (22) of the second circuit, the flow area of ​​the oil circuit (12b) and the oil circuit (22e) is continuously controlled, thereby adjusting the flow rate from the working port (10a) of the large cavity of the third oil cylinder (10) to the first oil inlet circuit (P1) and the second oil inlet circuit (P2).

7. A multi-pump multi-actuator circuit according to claim 6, characterized in that: When the third cylinder (10) retracts under a large gravitational load, the return oil pressure at the large working port (10a) of the third cylinder (10) is higher than the working pressure of the first cylinder (8) and the second cylinder (9). At the same time, when the first cylinder (8) and the second cylinder (9) move slightly: In the first circuit (1), the oil from the first variable pump (4) flows into the return oil circuit (T) through its outlet (4a), the inlet (11p) of the first reversing valve (11) of the first circuit, the oil circuit (11b), and the return oil port (11t), and then flows back to the oil tank (112). The first variable pump (4) is on standby at low pressure. In the second circuit (2), the oil from the second variable pump (5) flows into the return oil circuit (T) through its outlet (5a), the inlet (21p) of the first reversing valve (21) of the second circuit, the oil circuit (21b), and the return oil port (21t), and then flows back to the oil tank (112). The second variable pump (5) is on standby at low pressure. In the third circuit (3), the oil from the third variable pump (6) flows into the small working port (10b) of the third cylinder (10) through its outlet (6a), the second check valve (35) of the third circuit, the inlet (32p) of the second directional valve (32) of the third circuit, the second working port (32b), and the working oil passage (p32b); the oil from the large working port (10a) of the third cylinder (10) returns through the working port (22a) of the second directional valve (22) of the second circuit. After the oil flows into the return oil circuit (T) through the port (22t), it flows back to the oil tank (112). It also flows back to the oil tank (112) through the working oil port (12a) and return oil port (12t) of the second directional valve (12) of the first circuit. The third cylinder (10) retracts. The return oil from the working oil port (10a) of the large chamber of the third cylinder (10) flows into the third cylinder through the inlet (14p), working oil port (14a) of the fourth directional valve (14) of the first circuit and the fourth check valve (19) of the first circuit. The small working port (10b) of the hydraulic cylinder (10) forms a differential circuit to increase the retraction speed of the third hydraulic cylinder (10); when the pressure of the small working port (10b) of the third hydraulic cylinder (10) is lower than the pressure of the return oil circuit (T), the flow of the return oil circuit (T) flows through the fourth check valve (28) of the second circuit to the small working port (10b) of the third hydraulic cylinder (10) to avoid the retraction action stopping due to low pressure; at this time, the return oil from the large working port (10a) of the third hydraulic cylinder (10) passes through... The oil inlet (13p), working port (13a) of the first circuit third directional valve (13) and the first circuit second check valve (17) flow into the second oil inlet circuit (P2), driving the second cylinder (9) to move; at the same time, the return oil from the working port (10a) of the large chamber of the third cylinder (10) flows into the first oil inlet circuit (P1) through the oil port (13p) and oil port (13a) of the first circuit third directional valve (13) and the first circuit third check valve (18), driving the first cylinder (8) to move; By adjusting the pressure of the control chamber (12c) of the second reversing valve (12) of the first circuit and the pressure of the control chamber (12c) of the second reversing valve (22) of the second circuit, the flow area of ​​the oil circuit (12b) and the oil circuit (22e) is continuously controlled, thereby adjusting the flow rate from the large working port (10a) of the third cylinder (10) to the first oil inlet circuit (P1) and the second oil inlet circuit (P2); when the pressure of the small working port (10b) of the third cylinder (10) is higher than the return oil pressure of the large working port (10a), the fourth reversing valve (14) of the first circuit is in the first working position (X), cutting off the connection between its working port (14b) and working port (14a), and canceling the differential circuit oil replenishment function.

8. A multi-pump multi-actuator circuit according to claim 2, characterized in that: When the fourth directional valve (24) of the second circuit is in the third working position (N) and the second cylinder (9) is not in motion: In the second circuit (2), the oil from the second variable pump (5) flows into the small chamber working port (10b) of the third cylinder (10) through its outlet (5a), the third check valve (27) of the second circuit, the second inlet oil passage (P2), the second check valve (26) of the second circuit, the inlet (23p), oil passage (23a), and working port (23b) of the third directional valve (23) of the second circuit; the oil returning from the large chamber working port (10a) of the third cylinder (10) flows through the working port (22a) and return port (22t) of the second directional valve (22) of the second circuit. After entering the return oil circuit (T), the oil flows back to the oil tank (112), and after entering the return oil circuit (T) through the working oil port (12a) and return oil port (12t) of the second reversing valve (12) of the first circuit, the oil flows back to the oil tank (112), and the third cylinder (10) retracts; the return oil from the large chamber working oil port (10a) also flows into the small chamber working oil port (10b) of the third cylinder (10) through the oil inlet (14p) and working oil port (14a) of the fourth reversing valve (14) of the first circuit and the fourth check valve (19) of the first circuit, forming a differential circuit to increase the retraction speed of the third cylinder (10); When the pressure at the working port (10b) of the small chamber of the third cylinder (10) is lower than the pressure of the return oil circuit (T), the flow of the return oil circuit (T) flows through the fourth check valve (28) of the second circuit to the working port (10b) of the small chamber of the third cylinder (10) to avoid the retraction action stopping due to low pressure. At this time, the return oil from the working port (10a) of the large chamber flows into the second oil inlet circuit (P2) through the oil inlet (13p) and working port (13a) of the third directional valve (13) of the first circuit, and the second check valve (17) of the first circuit. It merges with the oil inlet of the second variable pump (5) and flows to the working port (10b) of the small chamber of the third cylinder (10), and the third cylinder (10) retracts. When the pressure at the outlet (5a) of the second variable pump (5) is higher than the pressure at the working port (10a) of the large chamber of the third cylinder (10), the second variable pump (5) supplies oil to the third cylinder (10); When the pressure at the outlet (5a) of the second variable pump (5) is lower than the pressure at the working port (10a) of the large chamber of the third cylinder (10), the first directional valve (21) of the second circuit is controlled to the third working position (Z), the second variable pump (5) is unloaded under low pressure, and at the same time, the return oil from the working port (10a) of the large chamber of the third cylinder (10) flows into the first oil inlet circuit (P1) through the inlet (13p), working port (13a) of the third directional valve (13) of the first circuit, and the third check valve (18) of the first circuit, thus driving the first cylinder (8) to move; By adjusting the pressure of the control chamber (12c) of the second reversing valve (12) of the first circuit and the pressure of the control chamber (12c) of the second reversing valve (22) of the second circuit, the flow area of ​​the oil circuit (12b) and the oil circuit (22e) is continuously controlled, thereby adjusting the flow rate from the working port (10a) of the large cavity of the third oil cylinder (10) to the first oil inlet circuit (P1) and the second oil inlet circuit (P2).

9. A multi-pump multi-actuator circuit according to claim 2, characterized in that: When it is necessary to adjust the ratio between the speed of the motor (7) and the extension and retraction of the third cylinder (10), the flow of the third variable pump (6) is diverted to the third cylinder (10) by switching the second reversing valve (32) of the third circuit to the first working position (X) or the second working position (Y).

10. An engineering machinery, characterized in that, Includes the multi-pump multi-actuator circuit according to any one of claims 1-9.

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