Hydraulic system and working machine

Abstract

The utility model belongs to the technical field of hydraulic transmission, and discloses a hydraulic system and an operating machine, and the hydraulic system comprises a plurality of action execution loops and a digital displacement pump. The digital displacement pump comprises a plurality of sets of output loops, and each set of output loops comprises a plurality of intra-set plunger assemblies, a shared flow distribution oil way, a shared switch valve used for controlling the on-off of the shared flow distribution oil way and an output oil way. And in any group of output loops, the plurality of intra-group plunger assemblies are connected with the shared flow distribution oil way and the output oil way, and the shared flow distribution oil way shunts oil from the plurality of intra-group plunger assemblies under the condition that the shared switch valve is switched on, so that the oil quantity reaching the output oil way from the plurality of intra-group plunger assemblies is adjusted. According to the system, only one digital displacement pump is needed to realize oil supply driving of a plurality of action execution loops, and each output loop in the digital displacement pump only needs one common switch valve to realize output displacement control, so that the number of the common switch valves is reduced, and the cost is greatly reduced.

Description

Technical Field

[0001] This utility model belongs to the field of hydraulic transmission technology, specifically relating to a hydraulic system and working machinery. Background Technology

[0002] In traditional hydraulic systems, single-pump drive of multiple action circuits relies on the coordination of pressure compensation valves and proportional valves, resulting in throttling and overflow losses and low efficiency. While multi-pump independent drive solutions improve the coordination of complex actions, they significantly increase installed power, installation size, and cost. The digital displacement pump aims to overcome this contradiction. The core principle of the digital displacement pump is to enable a single hydraulic pump to have multiple output circuit functions through the coordinated work of multiple plungers. By controlling the effective working stroke of the plungers inside the pump through high-speed switching valves, the displacement of each circuit can be independently adjusted.

[0003] The existing digital displacement pumps are equipped with at least one high-speed switching valve for each plunger, resulting in high system installation costs and a bulky structure, making it difficult to widely adopt them. Utility Model Content

[0004] In view of the above-mentioned defects or deficiencies, this utility model provides a hydraulic system and working machinery, which aims to solve the technical problems of high installation cost and bulky structure of existing hydraulic systems with digital displacement pumps.

[0005] To achieve the above objectives, this utility model provides a hydraulic system comprising several actuation circuits and a digital displacement pump. The digital displacement pump includes several sets of output circuits connected one-to-one with the actuation circuits. Each set of output circuits includes multiple intra-group plunger assemblies, a common distribution oil circuit, a common switching valve for controlling the on / off state of the common distribution oil circuit, and an output oil circuit. In any set of output circuits, the multiple intra-group plunger assemblies are connected to both the common distribution oil circuit and the output oil circuit. When the common switching valve is open, the common distribution oil circuit diverts the oil from the multiple intra-group plunger assemblies to regulate the amount of oil reaching the output oil circuit from the multiple intra-group plunger assemblies.

[0006] In an embodiment of this utility model, the output circuit further includes a first check valve, which is disposed between the plunger assembly in each group and the common distribution oil circuit. The first check valve is configured to open when hydraulic oil flows from the plunger assembly in the group to the common distribution oil circuit and to close in the reverse direction.

[0007] In an embodiment of this utility model, the output circuit further includes a second check valve, which is disposed between the plunger assembly in each group and the output oil circuit. The second check valve is configured to open when hydraulic oil flows from the plunger assembly in the group to the output oil circuit and to close in the reverse direction.

[0008] In an embodiment of this utility model, the output circuit further includes a replenishing oil circuit and a third check valve. Multiple intra-group plunger assemblies are connected to the replenishing oil circuit. The third check valve is disposed between each intra-group plunger assembly and the replenishing oil circuit. The third check valve is configured to open when hydraulic oil flows from the replenishing oil circuit to the intra-group plunger assembly and close in the reverse direction.

[0009] In an embodiment of this utility model, the multiple intra-group plunger assemblies include a first plunger assembly, a second plunger assembly, and a third plunger assembly, which share a common distribution oil passage and are respectively connected to the first plunger assembly, the second plunger assembly, and the third plunger assembly.

[0010] In an embodiment of this utility model, the common distribution oil circuit is also connected to the return oil circuit.

[0011] In embodiments of this utility model, the number of output circuits is at least two sets, and a merging oil circuit is connected between the output oil circuits of at least two sets of output circuits. A merging valve for controlling the opening and closing of the oil circuit is provided on the merging oil circuit.

[0012] In an embodiment of this utility model, the hydraulic system further includes an output control valve, which is integrated inside the digital displacement pump or located outside the digital displacement pump. The output control valve is used to control the connection and disconnection of the oil circuit between the output oil circuit and the corresponding action execution circuit.

[0013] In an embodiment of this utility model, the digital displacement pump further includes a rotor, which drives multiple intra-group plunger assemblies in the output circuit to suck and discharge oil according to a preset phase difference. The multiple intra-group plunger assemblies in any output circuit are evenly arranged along the circumferential rotation direction of the rotor of the digital displacement pump.

[0014] To achieve the above objectives, this utility model also provides a working machine, wherein the working machine includes the hydraulic system described above.

[0015] Through the above technical solution, the hydraulic system provided by this utility model embodiment has the following beneficial effects:

[0016] Based on the number of actuation loops, the existing digital displacement pump plunger assemblies are grouped, and each group is equipped with a shared distribution oil circuit, a shared switching valve, and an output oil circuit, forming one or more output loops. When there are multiple output loops, the digital displacement pump can achieve a "one pump, multiple outputs" function. Furthermore, since the plunger assemblies within each output loop share a common distribution oil circuit, each output loop only requires one shared switching valve to achieve independent adjustment of the loop's output displacement, reducing the system's requirement for multiple shared switching valves and effectively lowering costs.

[0017] Other features and advantages of this invention will be described in detail in the following detailed description section. Attached Figure Description

[0018] The accompanying drawings are provided to illustrate the present invention and form part of the specification. They are used together with the following detailed description to explain the present invention, but do not constitute a limitation thereof. In the drawings:

[0019] Figure 1 This is a hydraulic schematic diagram of the hydraulic system according to an embodiment of the present utility model;

[0020] Figure 2 This is a connection diagram of a digital displacement pump specifically applied to an electric excavator according to an embodiment of this utility model.

[0021] Explanation of reference numerals in the attached figures

[0022] 1. Digital displacement pump; 11. Output circuit; 11a. Output oil circuit; 11b. Make-up oil circuit; 11c. Common distribution oil circuit; 11d. Common switching valve; 11e. First check valve; 11f. Second check valve; 11g. Third check valve; 111. First plunger assembly; 112. Second plunger assembly; 113. Third plunger assembly; 14. Rotor; 15. Angle sensor; 2. Merging oil circuit; 21. Merging valve; 3. Output control valve; 41. Main motor; 42. Swing motor; 43. Travel motor; 44. Boom cylinder; 45. Bucket cylinder; 46. Stick cylinder; 5. Action execution circuit. Detailed Implementation

[0023] The specific embodiments of this utility model will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of this utility model.

[0024] The hydraulic system of this utility model is described below with reference to the accompanying drawings.

[0025] Some hydraulic systems are driven by a digital displacement pump 1, which mainly consists of a rotor 14 and several piston assemblies. Depending on the driving method of the rotor 14, the digital displacement pump 1 can be divided into a swashplate digital pump and an eccentric wheel digital pump.

[0026] The swashplate digital pump employs an axial piston layout, the core of which lies in the uniform distribution of piston assemblies along the circumference of the swashplate rotor 14's central axis on the axial side of the rotor 14. The axes of all piston assemblies are strictly parallel to the central axis of the rotor 14, and a dynamic fit is formed between the piston slippers and the swashplate's tilt plane. When the swashplate rotates, the axial displacement component generated by the swashplate's tilt angle periodically acts on each piston, forcing the pistons to produce synchronous reciprocating motion within the cylinder. This precise coupling of axial displacement and cylinder volume change enables directional pulsating output of hydraulic oil along the axial direction.

[0027] The eccentric wheel digital pump is designed based on the radial plunger principle. The plunger assembly is evenly distributed along the radial side of the eccentric wheel circumferentially along the drive shaft, with each plunger axis perpendicular to the rotation center axis. A preset mechanical eccentricity exists between the geometric center of the eccentric wheel and the rotation center. During drive shaft rotation, the eccentric cam profile applies a periodic radial force to the plungers through the contact surface. This force is directly converted into radial displacement of the plungers, driving the plunger assembly to complete alternating oil suction and discharge cycles.

[0028] To improve operational efficiency, many construction machines are designed with complex actions, such as the winch winding rope when a crane rotates, the boom extending and retracting of a concrete pump truck, and the bucket movement when an excavator moves its boom. This requires the hydraulic system to have the function of individually adjusting the displacement of each action execution circuit.

[0029] For existing hydraulic systems with digital displacement pump 1, the "one pump, multiple outputs" function can be achieved by connecting different piston assemblies to different actuation circuits 5. When performing multiple outputs, to precisely control the displacement delivered to each circuit, existing digital displacement pump 1 typically sets up a distribution oil circuit between the working chamber and the return oil circuit of each piston assembly, and installs a high-speed switching valve on the distribution oil circuit for on / off control. When the piston assembly outputs oil, by controlling the opening time of the high-speed switching valve, part of the oil output by the piston assembly can enter the circuit, and part can return through the distribution oil circuit, thereby achieving displacement control for the corresponding circuit. However, because existing digital displacement pump 1 requires a large number of high-speed switching valves to achieve displacement control, the corresponding hydraulic system not only has high assembly costs but also a bulky structure.

[0030] In view of this, the present invention discloses a hydraulic system with a novel digital displacement pump 1 as its core, such as... Figure 1 As shown, the hydraulic system includes several motion execution circuits 5 and a digital displacement pump 1.

[0031] The digital displacement pump 1 includes several sets of output circuits 11 that are connected one-to-one with several action execution circuits 5. Each set of output circuits 11 includes multiple intra-group plunger assemblies, a common distribution oil circuit 11c, a common switching valve 11d for controlling the on / off of the common distribution oil circuit 11c, and an output oil circuit 11a.

[0032] In any output circuit 11, multiple intra-group plunger assemblies are connected to a common distribution oil circuit 11c and an output oil circuit 11a. When the common switching valve 11d is open, the common distribution oil circuit 11c diverts the oil from the multiple intra-group plunger assemblies to regulate the amount of oil reaching the output oil circuit 11a from the multiple intra-group plunger assemblies.

[0033] Specifically, taking each output circuit 11 as an example, which includes two intra-group plunger assemblies, such as... Figure 1 As shown, multiple intra-group plunger assemblies include a first plunger assembly 111 and a second plunger assembly 112. A common distribution oil passage 11c is connected to the first plunger assembly 111 and the second plunger assembly 112 respectively. The common distribution oil passage 11c can guide the oil back to the oil passage or to other positions. Assuming that the theoretical displacement of each plunger assembly is C for one revolution of the rotor 14, then in the output circuit 11 composed of the first plunger assembly 111 and the second plunger assembly 112, the maximum oil displacement that the output circuit 11 can output through the output oil passage 11a for each revolution of the rotor 14 is 2C. When the rotor 14 rotates, by controlling the opening and closing of the common switching valve 11d at appropriate times, part of the hydraulic oil output by the first plunger assembly 111 and / or the second plunger assembly 112 can be diverted through the common distribution oil passage 11c and partially flow to the output oil passage 11a, thereby realizing the adjustment of the actual external output displacement of the output oil passage 11a between 0 and 2C.

[0034] For example, taking each output circuit 11 as an example, which includes three internal plunger assemblies, such as Figure 1 As shown, based on the first plunger assembly 111 and the second plunger assembly 112, the multiple intra-group plunger assemblies may also include a third plunger assembly 113. In this case, by controlling the opening timing and opening duration of the common switching valve 11d, the actual external output displacement of the output oil circuit 11a can be adjusted between 0 and 3C.

[0035] In summary, the hydraulic system of this invention groups the piston assemblies of the original digital displacement pump according to the number of actuation circuits, and equips each group of piston assemblies with a common distribution oil circuit, a common switching valve, and an output oil circuit to form one or more output circuits 11. When there are multiple output circuits 11, the digital displacement pump can achieve the "one pump, multiple outputs" function. Furthermore, since the piston assemblies within each output circuit share a common distribution oil circuit, each output circuit only requires one common switching valve to achieve independent adjustment of the circuit's output displacement, reducing the system's requirement for a number of common switching valves and effectively lowering costs.

[0036] Understandably, the number of plunger assemblies within each output circuit 11 can be increased.

[0037] When the digital displacement pump 1 is running, since the plunger assemblies in the group are distributed at intervals along the circumferential direction of the central axis of the rotor 14, there will be an oil discharge phase difference between the plunger assemblies in the group in the output circuit 11.

[0038] Taking output circuit 11 as an example, which includes three groups of internal plunger assemblies, assuming that the three groups of internal plunger assemblies are arranged circumferentially along the central axis of rotor 14, and the phase angles of the three groups of internal plunger assemblies differ by 60°, then the oil discharge phase difference of the three groups of internal plunger assemblies is 60°. For the first plunger assembly, assuming that the plunger assembly discharges oil when rotor 14 rotates within 0-180° and draws oil within 180°-360°, then for the second plunger assembly, the plunger assembly discharges oil when rotor 14 rotates within 60°-240° and draws oil within 240°-360° and 0-60°. For the third plunger assembly, the plunger assembly discharges oil when rotor 14 rotates within 120°-300° and draws oil within 300°-360° and 0-120°. The specific oil suction and discharge conditions of each plunger assembly are shown in Table 1 below:

[0039]

[0040]

[0041] As shown in the table above, when the rotor 14 is between 0-60°, the first plunger assembly 111 discharges oil, while the second and third plunger assemblies 113 draw in oil. To prevent the hydraulic oil output from the first plunger assembly from flowing into the second and third plunger assemblies 113 through the common distribution oil passage 11c, a first check valve 11e can be installed between the common distribution oil passage 11c and the second and third plunger assemblies, respectively. Similarly, when the rotor 14 is between 180-240°, the second plunger assembly 112 and the third plunger assembly 113 discharge oil, while the first plunger assembly 111 draws in oil. To prevent oil leakage, a first check valve 11e can be installed between the common distribution oil passage 11c and the first plunger assembly.

[0042] That is, Figure 1 As shown, in this embodiment, a first check valve 11e can be respectively installed between each group of intra-group plunger assemblies in the output circuit 11 and the common distribution oil circuit 11c. The first check valve 11e is configured to open when hydraulic oil flows from the intra-group plunger assembly to the common distribution oil circuit 11c and close in the reverse direction. By setting the first check valve 11e, the cross-contamination of oil between the intra-group plunger assemblies can be avoided when the digital displacement pump 1 is working due to the phase difference in oil discharge between the intra-group plunger assemblies.

[0043] like Figure 1 As shown, in this embodiment, the output circuit 11 further includes a second check valve 11f. The second check valve 11f is disposed between the plunger assembly in each group and the output oil circuit 11a. The second check valve 11f is configured to open when hydraulic oil flows from the plunger assembly in the group to the output oil circuit 11a and to close in the reverse direction.

[0044] Within a set of output circuits 11, due to the oil discharge phase of each group's plunger assembly, there may be a situation where, in certain phase operating ranges, one group's plunger assembly is discharging oil while another group's plunger assembly is drawing in oil. To prevent the drawing-in plunger assembly from drawing in oil discharged from other groups' plunger assemblies into the output oil circuit 11a, a second check valve 11f can be installed between each group's plunger assembly and the output oil circuit 11a.

[0045] like Figure 1 As shown, in this embodiment, the output circuit 11 also includes a replenishing oil passage 11b and a third check valve 11g. Multiple intra-group plunger assemblies are connected to the replenishing oil passage 11b. The third check valve 11g is positioned between each intra-group plunger assembly and the replenishing oil passage 11b. The third check valve 11g is configured to open when hydraulic oil flows from the replenishing oil passage 11b to the intra-group plunger assembly and close in the reverse direction. The replenishing oil passage 11b is used to replenish oil to the plunger chamber of the intra-group plunger assembly when the plunger assembly draws oil. Through the cooperation of the replenishing oil passage 11b and the output oil passage 11a, the basic functions of the output circuit 11—oil drawing, plunger pressurization, and output—can be realized. By setting the third check valve 11g, the oil discharged from the intra-group plunger assembly can be prevented from flowing into the replenishing oil passage 11b.

[0046] like Figure 1 As shown, in this embodiment, the number of output circuits 11 can be one or more groups depending on the number of action execution circuits 5, such as... Figure 1 In the illustrated embodiment, the digital displacement pump 1 has a total of nine plunger assemblies, which are divided into three groups to form three output circuits 11. The three output circuits 11 enable the digital displacement pump 1 to achieve a one-pump-three-output function. Each output circuit 11 is equipped with its own common distribution oil circuit 11c, common switching valve 11d, output oil circuit 11a, and replenishment oil circuit 11b. The output displacement of the corresponding output circuit 11 can be independently adjusted through the common switching valve 11d.

[0047] like Figure 1 As shown, in this embodiment, the hydraulic system also includes an output control valve 3. The output control valve 3 can be integrated into the digital displacement pump 1 or set on the outside of the digital displacement pump 1. The output control valve 3 is used to control the connection and disconnection of the oil circuit between the output oil circuit 11a and the action execution circuit 5.

[0048] Some operating machinery has actuators with both high-speed and slow-speed operation functions. The high-speed and slow-speed operations require different pump displacements. To diversify the pump's oil supply modes, such as... Figure 1As shown, in this embodiment, the output oil circuits 11a in two or more output circuits 11 can be connected through the confluence oil circuit 2, and a confluence valve 21 for controlling the opening and closing of the oil circuit is provided on the confluence oil circuit 2, so that the digital displacement pump 1 can realize the confluence output function and the individual output function of each output circuit 11.

[0049] In this embodiment, the intra-group plunger assemblies in each output circuit 11 are preferably arranged uniformly along the circumferential rotation direction of the rotor 14 of the digital displacement pump 1. The uniform arrangement can avoid the occurrence of oil supply vacuum periods in the output circuit 11.

[0050] If each output circuit 11 contains three intra-group plunger assemblies, then according to the principle of uniform arrangement, the phase angle difference between the three intra-group plunger assemblies is 360° / 3 = 120°. The oil suction and discharge situation of the three intra-group plunger assemblies with a phase angle difference of 120° is shown in Table 2 below:

[0051]

[0052]

[0053] As shown in the table above, when the rotor 14 rotates to any position, at least one intra-group plunger assembly in the output circuit 11 will output hydraulic oil to the outside, thereby ensuring that the output circuit 11 can continuously output hydraulic oil and avoid the oil supply vacuum period in the output circuit 11.

[0054] Taking each output circuit 11 containing four intra-group plunger assemblies as an example, according to the principle of uniform arrangement, the phase angle difference between the four intra-group plunger assemblies is 360° / 4 = 90°. Correspondingly, the oil suction and discharge situation of the four intra-group plunger assemblies is shown in Table 3 below:

[0055]

[0056] As shown in the table above, even when the rotor 14 rotates to any position, it can still ensure that at least one intra-group plunger assembly in the output circuit 11 outputs hydraulic oil.

[0057] like Figure 1 As shown, in this embodiment, the digital arrangement pump also includes an angle sensor 15 for real-time detection of the angle of the rotor 14, which can determine the phase working range of the rotor.

[0058] To achieve the above objectives, this utility model also discloses a working machine, wherein the working machine includes the hydraulic system described above.

[0059] like Figure 2As shown, the operating machinery can be an electric excavator, which includes a main motor 41, a swing motor 42, a travel motor 43, and a digital displacement pump 1. The main motor 41 drives the digital displacement pump 1 in the hydraulic system, the swing motor 42 drives the swing motor of the vehicle body, and the travel motor 43 drives the travel wheels. Figure 1 and Figure 2 In the illustrated embodiment, the digital displacement pump 1 may be provided with three sets of output circuits 11 (i.e. Figure 2 The three P ports (port 11) and three sets of output circuits 11 are respectively connected to the working circuits of the boom cylinder 44, bucket cylinder 45, and stick cylinder 46. Through the digital displacement pump 1, one pump independently supplies oil to the boom, bucket, and stick, and the oil supply displacement of each working circuit can be adjusted individually. Furthermore, the slewing and traveling movements of the electric excavator in this embodiment adopt a direct-drive motor design, simplifying the system and resulting in higher coordination and efficiency of composite movements.

[0060] In this embodiment, the operating machinery can also be a crane, aerial work platform, concrete pump truck, agricultural machinery, or other mechanical equipment with hydraulic actuation functions.

[0061] In the description of this utility model, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this utility model, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0062] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0063] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present 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. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0064] Although embodiments of the present invention have been described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A hydraulic system, characterized in that, The hydraulic system includes: Several action execution loops (5); The digital displacement pump (1) includes several sets of output circuits (11) that are connected one-to-one with the several action execution circuits (5). Each set of output circuits (11) includes multiple intra-group plunger assemblies, a common distribution oil circuit (11c), a common switching valve (11d) for controlling the oil circuit opening and closing of the common distribution oil circuit (11c), and an output oil circuit (11a). In any of the output circuits (11), the plurality of intra-group plunger assemblies are connected to the common distribution oil circuit (11c) and the output oil circuit (11a). When the common switching valve (11d) is open, the common distribution oil circuit (11c) diverts the oil from the plurality of intra-group plunger assemblies to regulate the amount of oil reaching the output oil circuit (11a) from the plurality of intra-group plunger assemblies.

2. The hydraulic system according to claim 1, characterized in that, The output circuit (11) further includes a first check valve (11e), which is disposed between each of the group intra-plunger assemblies and the common distribution oil circuit (11c). The first check valve (11e) is configured to open when hydraulic oil flows from the group intra-plunger assembly to the common distribution oil circuit (11c) and close in the reverse direction.

3. The hydraulic system according to claim 1, characterized in that, The output circuit (11) further includes a second check valve (11f), which is disposed between each of the group-in-group plunger assemblies and the output oil passage (11a). The second check valve (11f) is configured to open when hydraulic oil flows from the group-in-group plunger assembly to the output oil passage (11a) and close in the reverse direction.

4. The hydraulic system according to claim 1, characterized in that, The output circuit (11) further includes a replenishing oil passage (11b) and a third check valve (11g). The plurality of intra-group plunger assemblies are all connected to the replenishing oil passage (11b). The third check valve (11g) is disposed between each intra-group plunger assembly and the replenishing oil passage (11b). The third check valve (11g) is configured to open when hydraulic oil flows from the replenishing oil passage (11b) to the intra-group plunger assembly and to close in the reverse direction.

5. The hydraulic system according to claim 1, characterized in that, The plurality of intra-group plunger assemblies include a first plunger assembly (111), a second plunger assembly (112), and a third plunger assembly (113), and the common distribution oil passage (11c) is respectively connected to the first plunger assembly (111), the second plunger assembly (112), and the third plunger assembly (113).

6. The hydraulic system according to claim 1, characterized in that, The shared distribution oil passage (11c) is also connected to the return oil passage.

7. The hydraulic system according to any one of claims 1 to 6, characterized in that, The number of output circuits (11) is at least two sets, and a confluence oil circuit (2) is connected between the output oil circuits (11a) of at least two sets of output circuits (11). A confluence valve (21) for controlling the opening and closing of the oil circuit is provided on the confluence oil circuit (2).

8. The hydraulic system according to any one of claims 1 to 6, characterized in that, The hydraulic system also includes an output control valve (3), which is integrated in the digital displacement pump (1) or located on the outside of the digital displacement pump (1). The output control valve (3) is used to control the connection and disconnection of the oil circuit between the output oil circuit (11a) and the corresponding action execution circuit (5).

9. The hydraulic system according to any one of claims 1 to 6, characterized in that, The digital displacement pump (1) further includes a rotor (14), which is used to drive a plurality of intra-group plunger assemblies in the output circuit (11) to suck and discharge oil according to a preset phase difference, wherein the plurality of intra-group plunger assemblies in any output circuit (11) are uniformly arranged along the circumferential rotation direction of the rotor (14) of the digital displacement pump (1).

10. A type of operating machinery, characterized in that, Includes the hydraulic system according to any one of claims 1 to 9.

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