Hydraulic system of excavator and excavator

Abstract

The utility model relates to the technical field of engineering machinery, and discloses a hydraulic system of an excavator and the excavator. The hydraulic system comprises a first main pump, a second main pump, a third main pump, a fourth main pump, a main control valve, an auxiliary control valve, a bucket oil cylinder, a bucket rod oil cylinder, a movable arm oil cylinder, a walking motor and a rotary motor. The first main pump and the second main pump are connected with the bucket oil cylinder, the bucket rod oil cylinder, the movable arm oil cylinder and the walking motor through the main control valve. The third main pump and the fourth main pump are connected with the rotary motor through the auxiliary control valves and are connected with at least two of the bucket oil cylinder, the bucket rod oil cylinder and the movable arm oil cylinder through the auxiliary control valves; when a movable arm, a bucket, a bucket rod and rotation of the excavator act, the first main pump supplies oil to the movable arm oil cylinder, the second main pump supplies oil to the bucket rod oil cylinder, the third main pump supplies oil to the rotation motor, and the fourth main pump supplies oil to the bucket oil cylinder. Each pump is responsible for an independent hydraulic loop to achieve accurate control over all the loops, throttling losses are reduced, and oil consumption of the whole machine is reduced.

Description

Technical Field

[0001] This utility model relates to the field of engineering machinery technology, specifically to the hydraulic system of an excavator and the excavator itself. Background Technology

[0002] Large excavators have become essential machinery in mining operations. With the increase in overall tonnage, system flow rates increase, and the number of hydraulic pumps also increases. During operation, excavators typically require the boom, stick, and bucket to work together, as well as to perform traveling and slewing operations. Slewing, as the control action of the upper platform, involves frequent compound movements between slewing and the boom, stick, and bucket. Therefore, the energy consumption of the slewing hydraulic system accounts for a significant portion of the excavator's hydraulic system.

[0003] Currently, the hydraulic system of an excavator includes two main pumps, a main control valve, two swing pumps, a first swing control valve, a second swing valve, and a swing motor. One swing pump is connected to the swing motor only through the first swing control valve, while the other swing pump is connected to both the swing motor and the main control valve through the second swing control valve. This means only one swing pump can divert fluid to the main control valve, failing to fully utilize the two swing pumps when there is no swing action. When there are four combined actions—boom, stick, bucket, and swing—the same pump or circuit supplies fluid to two or more actions. Taking a circuit supplying both the boom and swing as an example, the boom lifting action is higher, while the swing pressure is lower. To prevent excessive hydraulic oil from flowing to the swing action, the swing valve core needs to be throttled to a pressure equivalent to the boom pressure to ensure the flow is distributed in the desired proportion. The product of the pressure difference ΔP between the swing and boom and the swing flow rate Q is the additional loss caused by throttling, resulting in significant throttling losses. Utility Model Content

[0004] In view of this, the present invention provides a hydraulic system for an excavator and an excavator to solve the problem of large throttling losses caused by the need to throttle the valve core when the excavator is performing compound actions, as the same pump or circuit supplies two or more actions.

[0005] In a first aspect, this utility model provides a hydraulic system for an excavator, comprising: a first main pump, a second main pump, a third main pump, a fourth main pump, a main control valve, an auxiliary control valve, a bucket cylinder, a stick cylinder, a boom cylinder, a travel motor, and a swing motor; the first main pump and the second main pump are connected to the bucket cylinder, the stick cylinder, the boom cylinder, and the travel motor via the main control valve; the third main pump and the fourth main pump are connected to the swing motor via the auxiliary control valve, and are also connected to at least two of the bucket cylinder, the stick cylinder, and the boom cylinder via the auxiliary control valve; when the excavator's boom, bucket, stick, and swing are in motion, the first main pump supplies oil to the boom cylinder, the second main pump supplies oil to the stick cylinder, the third main pump supplies oil to the swing motor, and the fourth main pump supplies oil to the bucket cylinder.

[0006] Beneficial effects: When the boom, bucket, stick, and swing are in motion, the flow distribution is as follows: the first main pump supplies oil to the boom cylinder, the second main pump supplies oil to the stick cylinder, the third main pump supplies oil to the swing motor, and the fourth main pump supplies oil to the bucket cylinder. This allows each pump to be responsible for an independent hydraulic circuit, i.e., four pumps and four circuits, thereby controlling the output flow and pressure of each pump and achieving precise control of each circuit. It eliminates the need for valve core throttling, reducing throttling losses and thus lowering overall machine fuel consumption. This effectively solves the problem of large throttling losses caused by a single pump or circuit supplying oil to two or more movements during excavator compound actions.

[0007] In one optional implementation, the main control valve includes a boom linkage and a stick linkage, the auxiliary control valve includes a swing linkage and a bucket linkage, the third main pump is connected to the swing motor through the swing linkage, the fourth main pump is connected to the bucket cylinder through the bucket linkage, the first main pump is connected to the boom cylinder through the boom linkage, and the second main pump is connected to the stick cylinder through the stick linkage.

[0008] Beneficial effects: Both the main control valve and the auxiliary control valve achieve precise control of multiple hydraulic circuits through each linkage, ensuring the stability and reliability of the system.

[0009] In one optional implementation, the main control valve includes a boom linkage and a bucket linkage, and the auxiliary control valve includes a swing linkage and a stick linkage. The first main pump is connected to the boom cylinder through the boom linkage, the second main pump is connected to the stick cylinder through the bucket linkage, the third main pump is connected to the swing motor through the swing linkage, and the fourth main pump is connected to the bucket cylinder through the stick linkage.

[0010] Beneficial effects: Both the main control valve and the auxiliary control valve achieve precise control of multiple hydraulic circuits through each linkage, ensuring the stability and reliability of the system.

[0011] In one alternative implementation, the auxiliary control valve further includes a rotary double-acting valve, and the fourth main pump is connected to the rotary motor via the rotary double-acting valve.

[0012] Beneficial effects: When the slewing motor operates alone or in conjunction with one or two of the boom, bucket, or stick movements, the third and fourth main pumps supply oil to the slewing motor. Even if one pump fails, the other can continue operating, ensuring the normal operation of the system. The two pumps can provide a higher total flow rate to meet the demands of high-power slewing motors and offer faster response times, especially in conditions requiring rapid start-up and shutdown, allowing for more swift adjustment of oil flow and pressure.

[0013] In one optional embodiment, the main control valve further includes a boom tandem, and the auxiliary control valve further includes a boom tertiary, with the first main pump connected to the boom cylinder via the boom tandem and the third main pump connected to the boom cylinder via the boom tertiary.

[0014] Beneficial effects: When the stick moves alone, the first, second and third main pumps supply oil to the stick cylinder. The simultaneous operation of the three main pumps can provide a higher total flow rate, meeting the needs of high-power stick cylinders.

[0015] In one optional implementation, the main control valve further includes a boom double valve, the auxiliary control valve further includes a boom triple valve, the second main pump is connected to the boom cylinder through the boom double valve, and the third main pump is connected to the boom cylinder through the boom triple valve.

[0016] Beneficial effects: When the boom moves alone, the boom cylinder is supplied with oil through the first, second and third main pumps. The simultaneous operation of the three pumps can provide a higher total flow rate to meet the needs of high-power boom cylinders. The multi-pump system can reduce system lag caused by insufficient flow of a single pump and improve the dynamic performance of the system.

[0017] In one alternative implementation, the main control valve further includes a bucket shunt, and the second main pump is connected to the bucket cylinder via the bucket shunt.

[0018] Beneficial effects: When the bucket operates alone, the first, second and fourth main pumps supply oil to the bucket cylinder. The simultaneous operation of the three pumps can provide a higher total flow rate, meeting the needs of high-power bucket cylinders. The multi-pump system can reduce system lag caused by insufficient flow from a single pump and improve the dynamic performance of the system.

[0019] In one alternative embodiment, the hydraulic system further includes a transfer case having a first output shaft and a second output shaft, the first output shaft being connected to a first master pump and a second master pump, and the second output shaft being connected to a third master pump and a fourth master pump.

[0020] Beneficial effects: The transfer case distributes power evenly through two output shafts, ensuring a stable power input to each pump and reducing power transmission losses. The transfer case can evenly distribute engine power to the four main pumps, simplifying system layout, reducing the number of pipes and connections, and improving system compactness and reliability.

[0021] In one optional implementation, there are two travel motors, namely a left travel motor and a right travel motor. The main control valve also includes a right travel link, a left travel link, and a linear travel link. The first main pump is connected to the right travel motor through the right travel link, the second main pump is connected to the left travel motor through the left travel link, and the first main pump is connected to the linear travel link.

[0022] Beneficial effects: By controlling the left and right travel motors separately with two main pumps, the coordinated operation of the two pumps enables more precise flow and pressure control, improving the motion accuracy of the travel motors. The first main pump is connected to the linear travel mechanism, providing additional oil supply when linear travel is required, ensuring synchronized movement of the travel motors and improving the accuracy and stability of linear travel.

[0023] Secondly, this utility model also provides an excavator, including the aforementioned hydraulic system. Attached Figure Description

[0024] To more clearly illustrate the specific embodiments of this utility model or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this utility model. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0025] Figure 1 This is a hydraulic schematic diagram of the hydraulic system of an excavator according to an embodiment of the present utility model;

[0026] Figure 2 for Figure 1 The schematic diagram of the auxiliary control valve and rotary motor is shown.

[0027] Figure 3 for Figure 1 The diagram shows the main control valve and its connected actuators.

[0028] Explanation of reference numerals in the attached figures:

[0029] 1. First main pump; 2. Second main pump; 3. Third main pump; 4. Fourth main pump;

[0030] 5. Main control valve;

[0031] 5011, boom in phase 1; 5012, boom in phase 2;

[0032] 5021, Bucket Unit 1; 5022, Bucket Unit 2;

[0033] 5031, Single-unit boom; 5032, Double-unit boom;

[0034] 5041, Right-walking sequence; 5042, Left-walking sequence;

[0035] 5051, Straight-line travel coupler; 5052, Spare coupler;

[0036] 6. Auxiliary control valve;

[0037] 6011, Rotation 1st section; 6012, Rotation 2nd section;

[0038] 6013, boom triple connection;

[0039] 6023, triple bucket assembly.

[0040] 7. Boom cylinder;

[0041] 8. Bucket hydraulic cylinder;

[0042] 9. Stalk cylinder;

[0043] 10. Right travel motor;

[0044] 11. Left travel motor;

[0045] 12. Rotary motor;

[0046] 13. Transfer case. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0048] The following is combined with Figures 1 to 3 The following describes embodiments of the present invention.

[0049] According to an embodiment of the present invention, a hydraulic system for an excavator is provided, comprising: a first main pump 1, a second main pump 2, a third main pump 3, a fourth main pump 4, a main control valve 5, an auxiliary control valve 6, a bucket cylinder 8, a stick cylinder 9, a boom cylinder 7, a travel motor, and a swing motor 12.

[0050] Specifically, the first main pump 1 and the second main pump 2 are connected to the bucket cylinder 8, the stick cylinder 9, the boom cylinder 7, and the travel motor via the main control valve 5; the third main pump 3 and the fourth main pump 4 are connected to the swing motor 12 via the auxiliary control valve 6, and are also connected to at least two of the bucket cylinder 8, the stick cylinder 9, and the boom cylinder 7 via the auxiliary control valve 6. When the excavator's boom, bucket, stick, and swing are in motion, the first main pump 1 supplies oil to the boom cylinder 7, the second main pump 2 supplies oil to the stick cylinder 9, the third main pump 3 supplies oil to the swing motor 12, and the fourth main pump 4 supplies oil to the bucket cylinder 8.

[0051] The hydraulic system of the excavator using this embodiment distributes flow as follows during boom, bucket, stick, and swing operations: the first main pump 1 supplies oil to the boom cylinder 7, the second main pump 2 supplies oil to the stick cylinder 9, the third main pump 3 supplies oil to the swing motor 12, and the fourth main pump 4 supplies oil to the bucket cylinder 8. This allows each pump to operate on an independent hydraulic circuit (four pumps, four circuits), enabling precise control of the output flow and pressure of each pump and achieving precise control of each circuit. This eliminates the need for valve core throttling, reducing throttling losses and lowering overall machine fuel consumption. It effectively solves the problem of large throttling losses caused by the need for valve core throttling when the same pump or circuit supplies oil for two or more operations during complex excavator movements.

[0052] In one embodiment, such as Figure 2 and Figure 3 As shown, the main control valve 5 includes a boom linkage 5011 and a stick linkage 5031, the auxiliary control valve 6 includes a swing linkage 6011 and a bucket linkage 6023, the third main pump 3 is connected to the swing motor 12 through the swing linkage 6011, the fourth main pump 4 is connected to the bucket cylinder 8 through the bucket linkage 6023, the first main pump 1 is connected to the boom cylinder 7 through the boom linkage 5011, and the second main pump 2 is connected to the stick cylinder 9 through the stick linkage 5031.

[0053] It should be noted that both the main control valve 5 and the auxiliary control valve 6 are multi-port valves. A multi-port valve includes a valve body and a valve core. Each port of the multi-port valve includes an oil inlet, an oil outlet, an oil return port, a working oil port, and a valve core. Each port is responsible for an independent hydraulic circuit.

[0054] Both the main control valve 5 and the auxiliary control valve 6 achieve precise control of multiple hydraulic circuits through each linkage, ensuring the stability and reliability of the system.

[0055] Furthermore, such as Figure 2 and Figure 3 As shown, the auxiliary control valve 6 also includes a swing double pump 6012, and the fourth main pump 4 is connected to the swing motor 12 via the swing double pump 6012. When the swing operates alone or in conjunction with one or both of the boom, bucket, and stick, the third main pump 3 and the fourth main pump 4 supply oil to the swing motor 12. Even if one pump fails, the other pump can continue to operate, ensuring the normal operation of the system. The two pumps can provide a higher total flow rate to meet the needs of the high-power swing motor 12, and can provide a faster response speed, especially in operating conditions requiring rapid start and stop, allowing for more rapid adjustment of oil flow and pressure.

[0056] Specifically, such as Figure 2 and Figure 3As shown, the main control valve 5 also includes a boom double unit 5012, and the auxiliary control valve 6 also includes a boom triple unit 6013. The second main pump 2 is connected to the boom cylinder 7 via the boom double unit 5012, and the third main pump 3 is connected to the boom cylinder 7 via the boom triple unit 6013. When the boom moves independently, oil is supplied to the boom cylinder 7 through the first main pump 1, the second main pump 2, and the third main pump 3. The simultaneous operation of the three pumps can provide a higher total flow rate, meeting the needs of the high-power boom cylinder 7. The multi-pump system can reduce system lag caused by insufficient flow from a single pump and improve the dynamic performance of the system.

[0057] Furthermore, such as Figure 2 and Figure 3 As shown, the main control valve 5 also includes a bucket primary unit 5021 and a bucket secondary unit 5022. The first main pump 1 is connected to the bucket cylinder 8 through the bucket primary unit 5021, and the second main pump 2 is connected to the bucket cylinder 8 through the bucket secondary unit 5022. When the bucket operates independently, oil is supplied to the bucket cylinder 8 through the first main pump 1, the second main pump 2, and the fourth main pump 4. The simultaneous operation of the three pumps can provide a higher total flow rate, meeting the needs of the high-power bucket cylinder 8. The multi-pump system can reduce system lag caused by insufficient flow from a single pump and improve the dynamic performance of the system.

[0058] Specifically, such as Figure 2 and Figure 3 As shown, the main control valve 5 also includes a boom double unit 5032. The first main pump 1 is connected to the boom cylinder 9 through the boom double unit 5032. When the boom moves alone, the first main pump 1 and the second main pump 2 supply oil to the boom cylinder 9. The simultaneous operation of the two main pumps can provide a higher total flow rate to meet the needs of the high-power boom cylinder 9.

[0059] Furthermore, such as Figure 2 and Figure 3 As shown, there are two travel motors, namely the left travel motor 11 and the right travel motor 10. The main control valve 5 also includes a right travel coupling 5041, a left travel coupling 5042 and a linear travel coupling 5051. The first main pump 1 is connected to the right travel motor 10 through the right travel coupling 5041, the second main pump 2 is connected to the left travel motor 11 through the left travel coupling 5042, and the first main pump 1 is connected to the linear travel coupling 5051.

[0060] Two main pumps control the left and right travel motors 10 respectively. The coordinated operation of the two pumps enables more precise flow and pressure control, improving the motion accuracy of the travel motors. The first main pump 1 is connected to the linear travel coupling 5051, which can provide additional oil supply when linear travel is required, ensuring the synchronous operation of the travel motors and improving the accuracy and stability of linear travel.

[0061] Specifically, such as Figure 2 and Figure 3As shown, the main control valve 5 also includes a backup connection 5052. The second main pump is connected to the backup connection 5052. When the main control valve 5 fails or malfunctions, the backup connection 5052 can serve as an emergency measure to take over some or all of the control functions, ensuring that some or all of the system functions can continue to operate.

[0062] Specifically, when the auxiliary control valve 6 includes a swing joint 6011, a swing joint 6012, a bucket joint 6023, and a boom joint 6013, the auxiliary control valve 6 has dual oil inlets and a four-way valve core. The main pump flow distribution for each single action and compound action is shown in Table 1 below.

[0063] Table 1

[0064]

[0065]

[0066] It should be noted that "×" in Table 1 means that the corresponding main pump does not supply oil to any actuator.

[0067] As can be seen from Table 1:

[0068] When the boom moves independently, the first main pump 1, the second main pump 2 and the third main pump 3 simultaneously supply oil to the boom cylinder 7.

[0069] When the stick moves independently, the first main pump 1 and the second main pump 2 simultaneously supply oil to the stick cylinder 9.

[0070] When the bucket operates independently, the first main pump 1, the second main pump 2, and the fourth main pump 4 simultaneously supply oil to the bucket cylinder 8.

[0071] When the slewing motor operates independently, the third main pump 3 and the fourth main pump 4 simultaneously supply oil to the slewing motor 12.

[0072] When the left travel is operated independently, the second main pump 2 supplies oil to the left travel motor 11.

[0073] When the right-walking motor operates independently, the first main pump 1 supplies oil to the right-walking motor 10.

[0074] When the boom and bucket move simultaneously, the first main pump 1 and the third main pump 3 supply oil to the boom cylinder 7 at the same time, and the second main pump 2 and the fourth main pump 4 supply oil to the bucket cylinder 8 at the same time.

[0075] When the boom and stick move simultaneously, the first main pump 1 and the third main pump 3 supply oil to the boom cylinder 7 at the same time, and the second main pump 2 supplies oil to the stick cylinder 9.

[0076] When the slewing and boom are moving simultaneously, the first main pump 1 and the second main pump 2 supply oil to the boom cylinder 7 at the same time, and the third main pump 3 and the fourth main pump 4 supply oil to the slewing motor 12 at the same time.

[0077] When the swing and bucket operate simultaneously, the first main pump 1 and the second main pump 2 supply oil to the bucket cylinder 8 at the same time, and the third main pump 3 and the fourth main pump 4 supply oil to the swing motor 12 at the same time.

[0078] When the slewing and stick movements are simultaneous, the first main pump 1 and the second main pump 2 simultaneously supply oil to the stick cylinder 9, and the third main pump 3 and the fourth main pump 4 simultaneously supply oil to the slewing motor 12.

[0079] When the stick and bucket move simultaneously, the first main pump 1 and the fourth main pump 4 supply oil to the bucket cylinder 8 at the same time, and the second main pump 2 supplies oil to the stick cylinder 9.

[0080] When the slewing, boom, and stick are operated simultaneously, the first main pump 1 supplies oil to the boom cylinder 7, the second main pump 2 supplies oil to the stick cylinder 9, and the third main pump 3 and the fourth main pump 4 simultaneously supply oil to the slewing motor 12.

[0081] When the boom, bucket, stick, and swing are in motion, the first main pump 1 supplies oil to the boom cylinder 7, the second main pump 2 supplies oil to the stick cylinder 9, the third main pump 3 supplies oil to the swing motor 12, and the fourth main pump 4 supplies oil to the bucket cylinder 8. At this time, the valve cores of the main control valve 5 and the auxiliary control valve 6 are: swing valve 6011, bucket valve 6023, boom valve 5011, and stick valve 5031.

[0082] It is understood that in another embodiment, the main control valve 5 is the same as in the above embodiment, only the auxiliary control valve 6 is different. Specifically, the auxiliary control valve 6 includes a swing valve 6011, a swing valve 6012, a bucket valve 6023, and a boom valve. The third main pump 3 is connected to the boom cylinder 9 through the boom valve, and the fourth main pump 4 is connected to the bucket cylinder 8 through the bucket valve 6023. The flow distribution of the main pumps for each single action and compound action can be adjusted adaptively by referring to Table 1.

[0083] It is understood that in another embodiment, the main control valve 5 is the same as in the above embodiment, only the auxiliary control valve 6 is different. Specifically, the auxiliary control valve 6 includes a swing valve 6011, a swing valve 6012, a boom valve 6013, and a stick valve. The third main pump 3 is connected to the boom cylinder 7 through the boom valve 6013, and the fourth main pump 4 is connected to the bucket cylinder 8 through the bucket valve 6023. The flow distribution of the main pumps for each single action and compound action can be adjusted adaptively by referring to Table 1.

[0084] It is understood that in another embodiment, the main control valve 5 is the same as in the above embodiment, only the auxiliary control valve 6 is different. Specifically, the auxiliary control valve 6 includes a swing linkage 6011, a swing linkage 6012, a boom linkage 6013, a bucket linkage 6023, and a stick linkage. The third main pump 3 is connected to the boom cylinder 7 through the boom linkage 6013, and the fourth main pump 4 is connected to the bucket cylinder 8 through the bucket linkage 6023. The third main pump 3 or the fourth main pump 4 is connected to the stick cylinder 9 through the stick linkage. The flow distribution of the main pumps for each single action and compound action can be adjusted adaptively by referring to Table 1.

[0085] In one embodiment, such as Figure 1 As shown, the hydraulic system also includes a transfer case 13, which has a first output shaft and a second output shaft. The first output shaft is connected to the first master pump 1 and the second master pump 2, and the second output shaft is connected to the third master pump 3 and the fourth master pump 4. The transfer case 13 distributes power evenly through the two output shafts, ensuring that each pump receives a stable power input and reducing power transmission losses. The transfer case 13 can evenly distribute the engine power to the four master pumps, simplifying the system layout, reducing the number of pipes and connectors, and improving the system's compactness and reliability.

[0086] According to an embodiment of the present invention, another aspect provides an excavator, including the aforementioned hydraulic system.

[0087] Furthermore, such as Figures 1 to 3 As shown, by adding an auxiliary control valve 6 to the excavator's hydraulic system, the auxiliary control valve 6 has dual inlets, connected to the third main pump 3 and the fourth main pump 4 respectively. The auxiliary control valve 6 includes a swing linkage 6011, a swing linkage 6012, a boom linkage 6013, and a bucket linkage 6023. The bucket linkage 6023 and the boom linkage 6013 are connected to the bucket cylinder 8 and the boom cylinder 7 respectively through pipelines. At this time, the auxiliary control valve 6 has a four-way valve core. By controlling each valve core, the corresponding actuator is controlled. Through the bucket linkage 6023 and the boom linkage 6013 of the auxiliary control valve 6, the third main pump 3 and the fourth main pump 4 can supply oil to the boom cylinder 7 and the bucket cylinder 8.

[0088] Specifically, during the four combined actions of boom, stick, bucket, and swing, the valve cores of the swing unit 6011, bucket unit 6023, boom unit 5011, and stick unit 5031 are controlled. The first main pump 1 supplies oil to the boom cylinder 7, the second main pump 2 supplies oil to the stick cylinder 9, the third main pump 3 supplies oil to the swing motor 12, and the fourth main pump 4 supplies oil to the bucket cylinder 8. This achieves flow distribution across four pumps and four circuits, fully realizing pump control without the need for valve cores to throttle the oil inlet, reducing throttling losses, and thus lowering the overall machine fuel consumption.

[0089] Furthermore, by using the boom triple unit 6013 and the bucket triple unit 6023, the third main pump 3 and the fourth main pump 4 can supply oil to the boom cylinder 7 and the bucket cylinder 8, thereby increasing the number of circuits. In this way, by diverting the flow through the third main pump 3 and the fourth main pump 4, the flow rate of the boom, bucket, boom and bucket, boom and stick, and stick and bucket movements can be increased, thereby improving the movement speed.

[0090] Specifically, during single boom operation, the first main pump 1, the second main pump 2, and the third main pump 3 supply oil to the boom cylinder 7, and the valve cores of boom linkage 5011, boom linkage 5012, and boom linkage 6013 are all activated. During double combined boom and stick operation, the first main pump 1 and the third main pump 3 supply oil to the boom cylinder 7, the valve cores of boom linkage 5011 and boom linkage 6013 are activated, the second main pump 2 supplies oil to the stick cylinder 9, and the valve core of stick linkage 5031 is activated. The boom cylinder 7 receives an additional main pump, which increases the boom speed and thus improves work efficiency.

[0091] Although embodiments of the present invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the present invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A hydraulic system for an excavator, characterized in that, include: First main pump (1), second main pump (2), third main pump (3), fourth main pump (4), main control valve (5), auxiliary control valve (6), bucket cylinder (8), boom cylinder (9), boom cylinder (7), travel motor and swing motor (12); The first main pump (1) and the second main pump (2) are connected to the bucket cylinder (8), the stick cylinder (9), the boom cylinder (7), and the travel motor through the main control valve (5); The third main pump (3) and the fourth main pump (4) are connected to the rotary motor (12) through the auxiliary control valve (6), and are also connected to at least two of the bucket cylinder (8), the stick cylinder (9), and the boom cylinder (7) through the auxiliary control valve (6). When the excavator's boom, bucket, stick, and slewing are in motion, the first main pump (1) supplies oil to the boom cylinder (7), the second main pump (2) supplies oil to the stick cylinder (9), the third main pump (3) supplies oil to the slewing motor (12), and the fourth main pump (4) supplies oil to the bucket cylinder (8).

2. The hydraulic system according to claim 1, characterized in that, The main control valve (5) includes a boom assembly (5011) and a stick assembly (5031). The auxiliary control valve (6) includes a swing assembly (6011) and a bucket assembly (6023). The third main pump (3) is connected to the swing motor (12) through the swing assembly (6011). The fourth main pump (4) is connected to the bucket cylinder (8) through the bucket assembly (6023). The first main pump (1) is connected to the boom cylinder (7) through the boom assembly (5011). The second main pump (2) is connected to the stick cylinder (9) through the stick assembly (5031).

3. The hydraulic system according to claim 1, characterized in that, The main control valve (5) includes a boom assembly (5011) and a bucket assembly (5021). The auxiliary control valve (6) includes a swing assembly (6011) and a stick assembly. The first main pump (1) is connected to the boom cylinder (7) through the boom assembly (5011). The second main pump (2) is connected to the stick cylinder (9) through the bucket assembly (5021). The third main pump (3) is connected to the swing motor (12) through the swing assembly (6011). The fourth main pump (4) is connected to the bucket cylinder (8) through the stick assembly.

4. The hydraulic system according to claim 2 or 3, characterized in that, The auxiliary control valve (6) also includes a rotary double unit (6012), and the fourth main pump (4) is connected to the rotary motor (12) through the rotary double unit (6012).

5. The hydraulic system according to claim 2, characterized in that, The main control valve (5) also includes a boom double unit (5032), and the auxiliary control valve (6) also includes a boom triple unit. The first main pump (1) is connected to the boom cylinder (9) through the boom double unit (5032), and the third main pump (3) is connected to the boom cylinder (9) through the boom triple unit.

6. The hydraulic system according to claim 2, 3, or 5, characterized in that, The main control valve (5) also includes a boom double unit (5012), and the auxiliary control valve (6) also includes a boom triple unit (6013). The second main pump (2) is connected to the boom cylinder (7) through the boom double unit (5012), and the third main pump (3) is connected to the boom cylinder (7) through the boom triple unit (6013).

7. The hydraulic system according to claim 2, 3, or 5, characterized in that, The main control valve (5) also includes a bucket double unit (5022), and the second main pump (2) is connected to the bucket cylinder (8) through the bucket double unit (5022).

8. The hydraulic system according to any one of claims 1 to 3, characterized in that, The hydraulic system also includes a transfer case (13), which has a first output shaft and a second output shaft. The first output shaft is connected to the first main pump (1) and the second main pump (2), and the second output shaft is connected to the third main pump (3) and the fourth main pump (4).

9. The hydraulic system according to any one of claims 1 to 3, characterized in that, The number of walking motors is two, namely a left walking motor (11) and a right walking motor (10). The main control valve (5) also includes a right walking link (5041), a left walking link (5042) and a straight walking link (5051). The first main pump (1) is connected to the right walking motor (10) through the right walking link (5041). The second main pump (2) is connected to the left walking motor (11) through the left walking link (5042). The first main pump (1) is connected to the straight walking link (5051).

10. An excavator, characterized in that, include: The hydraulic system according to any one of claims 1 to 9.

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