Excavator hydraulic drive system and excavator

Abstract

This invention discloses a hydraulic drive system for an excavator and the excavator itself. The system includes: a first pump whose outlet is connected via a first shut-off valve to a boom control valve for driving the boom cylinder; a first pump whose outlet is connected to a left travel control valve for driving the left travel motor; a second pump whose outlet is connected via a third shut-off valve to a stick control valve for driving the stick cylinder; a second pump whose outlet is connected to a right travel control valve for driving the right travel motor; a third pump whose outlet is connected to a bucket control valve for driving the bucket cylinder; and a fourth motor for driving a slewing reducer. This invention achieves complete decoupling between the upper actuators, eliminating energy waste caused by load coupling and improving operating efficiency. Simultaneously, independent control of the upper and lower vehicles improves overall machine maneuverability and operating efficiency, simplifies the hydraulic system structure, and reduces energy loss and manufacturing costs. Independent adjustment of each actuator facilitates system debugging and improves overall machine flexibility and operating performance.

Description

Technical Field

[0001] This invention belongs to the field of excavator technology, specifically relating to an excavator hydraulic drive system and an excavator. Background Technology

[0002] The hydraulic drive system of an excavator mainly consists of one or two hydraulic pumps, a hydraulic multi-way valve, and multiple hydraulic actuators. Actuators include boom cylinders, stick cylinders, bucket cylinders, swing motors, and left and right travel motors. Depending on the overall size of the excavator, the output flow of one or two hydraulic pumps is distributed to multiple hydraulic actuators via the hydraulic multi-way valve. During operation, the different flow requirements of each actuator and the coupled loads cause throttling and overflow losses through the hydraulic valves during flow distribution, resulting in energy waste. Furthermore, existing technologies suffer from the following drawbacks: significant overflow losses due to rotational inertia loads, and the inability to recover braking energy; poor maneuverability and low efficiency due to coupling during straight-line travel; complex hydraulic multi-way valve circuitry leading to significant energy losses and high costs; and complex flow distribution across multiple actuators resulting in long commissioning cycles. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a hydraulic drive system and excavator for an excavator, achieving complete decoupling between the upper actuators, eliminating energy waste caused by load coupling, and improving work efficiency. Simultaneously, independent control of the upper and lower vehicles enhances overall machine operability and work efficiency, simplifies the hydraulic system structure, and reduces energy loss and manufacturing costs. Independent adjustment of each actuator facilitates system debugging and improves overall machine flexibility and operational performance.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0005] In a first aspect, a hydraulic drive system for an excavator is provided, comprising: a first pump, the outlet of which is connected to the inlet of a boom control valve via a first shut-off valve; the boom control valve is used to drive a boom cylinder; the outlet of the first pump is connected to the inlet of a left travel control valve, which is used to drive a left travel motor; a second pump, the outlet of which is connected to the inlet of a stick control valve via a third shut-off valve; the stick control valve is used to drive a stick cylinder; the outlet of the second pump is connected to the inlet of a right travel control valve, which is used to drive a right travel motor; a third pump, the outlet of which is connected to the inlet of a bucket control valve, which is used to drive a bucket cylinder; and a fourth motor, which drives a slewing reducer to achieve slewing action.

[0006] Furthermore, the oil inlet of the boom control valve is connected to the oil outlet of the third pump through a second shut-off valve; the oil inlet of the stick control valve is connected to the oil outlet of the third pump through a fourth shut-off valve.

[0007] Furthermore, it also includes a fourth pump, wherein the oil inlet of the boom control valve is connected to the oil outlet of the fourth pump through a second shut-off valve; and the oil inlet of the stick control valve is connected to the oil outlet of the third pump through a fourth shut-off valve.

[0008] Furthermore, when the boom is raised in a single motion, both the first and second shut-off valves are in the connected position. The hydraulic oil output from the first and third pumps merges and enters the boom control valve, and then enters the rodless chamber of the boom cylinder through the boom control valve. The hydraulic oil in the rod chamber of the boom cylinder enters the oil tank through the return port of the boom control valve.

[0009] Furthermore, when the boom is raised in a single motion, both the first and second shut-off valves are in the connected position. The hydraulic oil output from the first and fourth pumps merges and enters the boom control valve, and then enters the rodless chamber of the boom cylinder through the boom control valve. The hydraulic oil in the rod chamber of the boom cylinder enters the oil tank through the return port of the boom control valve.

[0010] Furthermore, when the stick retracts or swings outward, both the third and fourth shut-off valves are in the connected position. The hydraulic oil output from the second and third pumps merges and enters the stick control valve, and then enters the rodless chamber of the stick cylinder through the stick control valve. The hydraulic oil in the rod chamber of the stick cylinder enters the oil tank through the return port of the stick control valve.

[0011] Furthermore, when the bucket operates in a single motion, the hydraulic oil output by the third pump enters the bucket control valve and then enters the rod-side or rodless-side chamber of the bucket cylinder through the bucket control valve, thereby controlling the bucket cylinder to achieve single motion.

[0012] Furthermore, when the left travel single action is performed, the hydraulic oil output by the first pump enters the left travel control valve and drives the left travel motor through the left travel control valve.

[0013] Furthermore, when the right travel single action is performed, the hydraulic oil output by the second pump enters the right travel control valve and drives the right travel motor through the right travel control valve.

[0014] Furthermore, when the boom and stick move in combination, the first, third, and fourth shut-off valves are all in the connected position, while the second shut-off valve is in the shut-off position. The hydraulic oil output from the first pump enters the boom control valve and controls the extension or retraction of the boom cylinder through the boom control valve. The hydraulic oil output from the second and third pumps merges and enters the stick control valve, which then controls the extension or retraction of the stick cylinder through the stick control valve.

[0015] Furthermore, when the boom and stick move in combination, the first, second, third, and fourth shut-off valves are all in the connected position; the hydraulic oil output from the first and fourth pumps enters the boom control valve and controls the extension or retraction of the boom cylinder through the boom control valve; the hydraulic oil output from the second and third pumps merges and enters the stick control valve, and controls the extension or retraction of the stick cylinder through the stick control valve.

[0016] Furthermore, when the boom, stick, and bucket operate in combination, the first and third shut-off valves are both in the connected position, while the second and fourth shut-off valves are both in the shut-off position. The hydraulic oil output from the first pump enters the boom control valve and controls the extension or retraction of the boom cylinder through the boom control valve. The hydraulic oil output from the second pump enters the stick control valve and controls the extension or retraction of the stick cylinder through the stick control valve. The hydraulic oil output from the third pump enters the bucket control valve and controls the extension or retraction of the bucket cylinder through the bucket control valve.

[0017] Furthermore, when the boom, stick, and bucket operate in combination, the first, second, third, and fourth shut-off valves are all in the connected position; the hydraulic oil output from the first and fourth pumps enters the boom control valve and controls the extension or retraction of the boom cylinder through the boom control valve; the hydraulic oil output from the second pump enters the stick control valve and controls the extension or retraction of the stick cylinder through the stick control valve; the hydraulic oil output from the third pump enters the bucket control valve and controls the extension or retraction of the bucket cylinder through the bucket control valve.

[0018] Furthermore, during the combined loading and unloading operation, the first and third shut-off valves are both in the cut-off position, while the second and fourth shut-off valves are both in the connected position. The hydraulic oil output from the first pump enters the left travel control valve, which controls the left travel motor to move forward or backward. The hydraulic oil output from the second pump enters the right travel control valve, which controls the right travel motor to move forward or backward. The hydraulic oil output from the third pump enters the bucket control valve, boom control valve, and stick control valve, which respectively control the extension or retraction of the bucket cylinder, boom cylinder, and stick cylinder.

[0019] Furthermore, during the combined loading and unloading operation, the first and third shut-off valves are both in the cut-off position, while the second and fourth shut-off valves are both in the connected position. The hydraulic oil output from the first pump enters the left travel control valve, which controls the left travel motor to move forward or backward. The hydraulic oil output from the second pump enters the right travel control valve, which controls the right travel motor to move forward or backward. The hydraulic oil output from the third pump enters the bucket control valve and the stick control valve, which control the extension or retraction of the bucket cylinder and the stick cylinder, respectively. The hydraulic oil output from the fourth pump enters the boom control valve, which controls the extension or retraction of the boom cylinder.

[0020] In a second aspect, an excavator is provided, the excavator being equipped with the excavator hydraulic drive system described in the first aspect.

[0021] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: The oil outlet of the first pump is connected to the oil inlet of the boom control valve through a first shut-off valve; the boom control valve drives the boom cylinder; the oil outlet of the first pump is connected to the oil inlet of the left travel control valve, which drives the left travel motor; the oil outlet of the second pump is connected to the oil inlet of the stick control valve through a third shut-off valve; the stick control valve drives the stick cylinder; the oil outlet of the second pump is connected to the oil inlet of the right travel control valve, which drives the right travel motor; the oil outlet of the third pump is connected to the oil inlet of the bucket control valve, which drives the bucket cylinder; a fourth motor drives the slewing reducer; and the upper vehicle is a composite system. During operation, the boom, stick, and bucket actuators are independently supplied with oil by different hydraulic pumps, and the slewing is independently electrically driven and controlled, achieving complete decoupling between the upper actuators, eliminating energy waste caused by load coupling, and improving work efficiency. During combined upper and lower actions (straight-line travel mode), the upper and lower vehicles are supplied with oil by different hydraulic pumps, eliminating the need for a straight-line travel valve, and the upper and lower vehicles are independently controlled, improving the overall machine's operability and work efficiency. The elimination of the slewing control valve and straight-line travel valve circuits simplifies the hydraulic multi-way valve structure and flow channel design, reduces energy loss, and saves manufacturing costs. Each actuator can be adjusted independently, facilitating system debugging and improving the overall machine's flexibility and operational performance. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the control principle of an excavator hydraulic drive system provided in Embodiment 1 of the present invention;

[0023] In the diagram: 1. First motor; 2. Second motor; 3. Third motor; 4. First pump; 5. Second pump; 6. Third pump; 7. Boom control valve; 8. Left travel control valve; 9. Stick control valve; 10. Right travel control valve; 11. Bucket control valve; 12. First shut-off valve; 13. Second shut-off valve; 14. Third shut-off valve; 15. Fourth shut-off valve; 16.1~16.2. First~Second load holding valves; 17.1~17.6. First~Sixth overload replenishing valves; 18. Boom cylinder; 19. Left travel motor; 21. Stick cylinder; 22. Right travel motor; 23. Bucket cylinder; 24. Oil tank; 25. Fourth motor; 26. Slewing reducer. Detailed Implementation

[0024] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0025] Example 1:

[0026] like Figure 1 As shown, an excavator hydraulic drive system includes a first motor 1 driving a first pump 4. The oil outlet of the first pump 4 is connected to the oil inlet of a boom control valve 7 via a first shut-off valve 12. The boom control valve 7 is used to drive a boom cylinder 18. The first oil outlet of the boom control valve 7 is connected to the rodless chamber of the boom cylinder 18 via a first load holding valve 16.1. The rodless chamber of the boom cylinder 18 is connected to an oil tank 24 via a first overload replenishing valve 17.1. The second oil outlet of the boom control valve 7 is connected to the rod chamber of the boom cylinder 18. The rod chamber of the boom cylinder 18 is connected to the oil tank 24 via a second overload replenishing valve 17.2. The oil outlet of the boom control valve 7 is connected to the oil tank 24.

[0027] The oil outlet of the first pump 4 is connected to the oil inlet of the left travel control valve 8, which is used to drive the left travel motor 19 forward or backward.

[0028] The second motor 2 drives the second pump 5. The oil outlet of the second pump 5 is connected to the oil inlet of the boom control valve 9 through the third shut-off valve 14. The boom control valve 9 is used to drive the boom cylinder 21. The first oil outlet of the boom control valve 9 is connected to the rodless chamber of the boom cylinder 21. The rodless chamber of the boom cylinder 21 is connected to the oil tank 24 through the third overload replenishment valve 17.3. The second oil outlet of the boom control valve 9 is connected to the rod chamber of the boom cylinder 21 through the second load holding valve 16.2. The rod chamber of the boom cylinder 21 is connected to the oil tank 24 through the fourth overload replenishment valve 17.4. The oil outlet of the boom control valve 9 is connected to the oil tank 24.

[0029] The oil outlet of the second pump 5 is connected to the oil inlet of the right travel control valve 10, which is used to drive the right travel motor forward or backward.

[0030] The third motor 3 drives the third pump 6. The oil outlet of the third pump 6 is connected to the oil inlet of the bucket control valve 11. The bucket control valve 11 is used to drive the bucket cylinder 23. The first oil outlet of the bucket control valve 11 is connected to the rodless chamber of the bucket cylinder 23. The rodless chamber of the bucket cylinder 23 is connected to the oil tank 24 through the fifth overload replenishing valve 17.5. The second oil outlet of the bucket control valve 11 is connected to the rod chamber of the bucket cylinder 23. The rod chamber of the bucket cylinder 23 is connected to the oil tank 24 through the sixth overload replenishing valve 17.6. The oil outlet of the bucket control valve 11 is connected to the oil tank 24.

[0031] The fourth motor 25 drives the rotary reducer 26 to achieve the rotary action.

[0032] The oil inlet of the boom control valve 7 is connected to the oil outlet of the third pump 6 through the second shut-off valve 13; the oil inlet of the stick control valve 9 is connected to the oil outlet of the third pump 6 through the fourth shut-off valve 15.

[0033] (1) Description of single-action working conditions.

[0034] When the boom rises in a single motion, the first motor 1 drives the first pump 4, and the first shut-off valve 12 is in the connected position. The power oil output from the first pump 4 enters the inlet of the boom control valve 7. Simultaneously, the third motor 3 drives the third pump 6, and the second shut-off valve 13 is in the connected position. The power oil output from the third pump 6 also enters the inlet of the boom control valve 7, achieving the merging of power oil from the first pump 4 and the third pump 6. The boom control valve 7 operates in the left position, and the merged power oil enters the rodless chamber of the boom cylinder 18 through the boom control valve 7. The oil in the rod chamber of the boom cylinder 18 returns to the oil tank 24 through the boom control valve 7. This working process enables the dual-pump merging oil supply during a single boom rise, ensuring the rapid operation required for the single boom rise.

[0035] The working process of the stick retraction and outward swing single action is similar to the boom raising single action. The power oil from the second pump 5 and the third pump 6 is combined through the third shut-off valve 14 and the fourth shut-off valve 15. The stick retraction and outward swing single actions are realized through the left and right working positions of the stick control valve 9, respectively, to ensure the speed requirement of the stick retraction and outward swing single action. The specific working process will not be described in detail.

[0036] The bucket's left and right travel actions can be met by a single pump supply, eliminating the need for a combined flow circuit. The first pump 4 supplies oil to the left travel motor 19 through the left travel control valve 8, the second pump 5 supplies oil to the right travel motor 22 through the right travel control valve 10, and the third pump 6 supplies oil to the bucket cylinder 23 through the bucket control valve 11, each achieving its own single action.

[0037] The slewing mechanism is driven by an independent electric motor. The fourth motor 25 drives the slewing reducer 26 to work, realizing single-action slewing. It eliminates the need for a traditional slewing hydraulic circuit, simplifies the hydraulic circuit design, and eliminates the overflow loss and throttling loss that exist in traditional hydraulic circuits. At the same time, the slewing braking energy can be recovered.

[0038] (2) Explanation of the combined action of getting on the vehicle.

[0039] Category 1: Compound actions without a bucket. Since the slewing is independently electrically driven, only the decoupling between the boom and stick movements needs to be considered. This will be explained using a flat terrain working condition:

[0040] Under flat ground conditions (boom + stick combined), the boom cylinder's required flow rate is less than that of a single pump, while the stick cylinder's required flow rate is greater than that of a single pump, and the load difference between the two is significant. Therefore, in traditional dual-pump hydraulic circuits, the loads are coupled, and to ensure reasonable flow distribution, a throttling design is needed to balance the load, resulting in a significant waste of throttling energy. This invention achieves complete decoupling of the boom and stick actuators. The working process is as follows:

[0041] The first motor 1 drives the first pump 4, and the first shut-off valve 12 operates in the connected position. The power oil from the first pump 4 enters the boom control valve 7. The left and right positions of the boom control valve 7 control the extension and retraction of the boom cylinder 18, respectively. At this time, the second shut-off valve 13 operates in the shut-off position, achieving single-pump, independent oil supply on the boom side, without coupling with the stick side. The second motor 2 drives the second pump 5, and the third motor 3 drives the third pump 6. The third shut-off valve 14 and the fourth shut-off valve 15 both operate in the connected position. The second pump 5 and the third pump 6 merge at the inlet of the stick control valve 9. The left and right positions of the stick control valve 9 control the extension and retraction of the stick cylinder 21, respectively. At this time, the stick is independently supplied with oil, without coupling with the boom side. Compared with the traditional hydraulic circuit, this eliminates the throttling loss caused by load coupling, improves system energy efficiency, and allows both the boom and stick sides to obtain more power oil, thus improving operating efficiency.

[0042] The second category: compound actions involving a bucket. Since the slewing is independently electrically driven, only the decoupling between the boom, stick, and bucket needs to be considered. Let's take the boom + stick + bucket compound action as an example:

[0043] During the combined boom, stick, and bucket motion, the first motor 1 drives the first pump 4, the second motor 2 drives the second pump 5, and the first shut-off valve 12 and the third shut-off valve 14 are in the connected position, supplying oil to the boom and stick sides respectively. The third motor 3 drives the third pump 6, and the second shut-off valve 13 and the fourth shut-off valve 15 are in the shut-off position, supplying oil only to the bucket side, not the boom or stick sides. This process achieves independent control of the boom, stick, and bucket, completely decoupling the load and eliminating throttling losses caused by load coupling.

[0044] Similarly, for other bucket-related complex actions, the third pump 6 only supplies oil to the bucket side, achieving independent control of the bucket side without coupling with other circuits.

[0045] As can be seen from the above, during the combined operation of the upper vehicle, the boom, stick, bucket, and slewing can all be controlled independently. The four actuators of the upper vehicle are completely decoupled, eliminating the energy waste caused by load coupling and improving the operating efficiency.

[0046] (3) Explanation of the combined actions of getting on and off the vehicle.

[0047] The combined action of mounting and dismounting refers to the linear travel condition. In traditional dual-pump hydraulic systems, a dedicated linear travel valve prioritizes the oil supply to the dismounting unit, while the oil supply to all actuators on the mounting unit is insufficient to meet the flow rate of a single pump. This can easily lead to cavitation and slow speed, resulting in poor maneuverability and low efficiency. The hydraulic drive system proposed in this invention can decouple the mounting and dismounting actions. The working principle of the linear travel condition is as follows:

[0048] The first motor 1 drives the first pump 4 to work, and the first shut-off valve 12 is in the shut-off position, ensuring that the power oil of the first pump 4 only enters the left travel control valve 8. The left and right positions of the left travel control valve 8 control the forward and backward movement of the left travel motor, respectively. The second motor 2 drives the second pump 5 to work, and the third shut-off valve 14 is in the shut-off position, ensuring that the power oil of the second pump 5 only enters the right travel control valve 10. The left and right positions of the right travel control valve 10 control the forward and backward movement of the right travel motor, respectively. The third motor 3 drives the third pump 6, and the second shut-off valve 13 and the fourth shut-off valve 15 are in the connected position. The power oil of the third pump 6 can enter the boom control valve 7, the stick control valve 9, and the bucket control valve 11, respectively, thereby controlling the boom cylinder 18, the stick cylinder 21, and the bucket cylinder 23 to move, respectively. Therefore, in the straight-line travel condition, the up-car movement is independently controlled by the third pump 6, and the left and right movement of the down-car is independently controlled by the first pump 4 and the second pump 5 respectively. The up-car and down-car movements are decoupled and do not interfere with each other. At the same time, the oil supply to the up-car and down-car movements is increased, improving maneuverability and work efficiency.

[0049] This invention relates to an excavator hydraulic drive system that solves the energy waste caused by load coupling when multiple actuators of an excavator perform compound actions. During compound operations on the upper and lower hulls, all actuators are independently controlled and completely decoupled, eliminating throttling energy loss caused by load coupling and reducing energy waste. Simultaneously, each actuator receives more hydraulic fluid, improving system operating efficiency. During compound operations on the upper and lower hulls, the upper and lower hulls are supplied with hydraulic fluid independently, achieving decoupling between them and increasing the hydraulic fluid supply to the actuators on both hulls, thus improving maneuverability and operating efficiency. A confluence circuit with a cut-off function is designed to meet both single-action speed requirements and flow distribution requirements under compound action conditions. The elimination of the linear travel valve and rotation-related hydraulic circuits simplifies the hydraulic multi-way valve structure, enabling modular design and reducing manufacturing costs. Independent adjustment of each actuator facilitates system debugging, improving overall machine flexibility and operating performance.

[0050] Example 2:

[0051] The difference between this embodiment and Embodiment 1 is that this embodiment further includes a fourth pump, and the oil inlet of the boom control valve 7 is connected to the oil outlet of the fourth pump through the second shut-off valve 13. The merging channel between the third pump 6 and the second shut-off valve 13 is eliminated. The differences between this embodiment and the first embodiment will be briefly described below.

[0052] (1) Description of single-action working conditions.

[0053] Compared to the first embodiment, the main difference in the single-action condition is that in the single-action boom operation, the first pump 4 directly supplies oil to the boom control valve 7, and the fourth pump 27 supplies oil to the boom control valve 7 through the second shut-off valve 13. The first and fourth pumps merge, and the third pump 6 does not need to merge with the boom side, thus eliminating the merging oil passage. The remaining single-action conditions are the same as in the first embodiment.

[0054] When the boom is raised in a single motion, the first shut-off valve 12 and the second shut-off valve 13 are both in the connected position. The hydraulic oil output from the first pump 4 and the fourth pump merges and enters the boom control valve 7, and then enters the rodless chamber of the boom cylinder 18 through the boom control valve 7. The hydraulic oil in the rod chamber of the boom cylinder 18 enters the oil tank 24 through the return port of the boom control valve 7.

[0055] (2) Explanation of the combined action of getting on the vehicle.

[0056] Compared with the first embodiment, the combined action of the upper vehicle is basically the same. The main difference is that the second shut-off valve 13 is in the connected position and the boom side is supplied with oil by dual pumps, which can help to further improve the operating efficiency.

[0057] When the boom and stick move in combination, the first shut-off valve 12, the second shut-off valve 13, the third shut-off valve 14, and the fourth shut-off valve 15 are all in the connected position; the hydraulic oil output from the first pump 4 and the fourth pump enters the boom control valve 7, and controls the boom cylinder 18 to extend or retract through the boom control valve 7; the hydraulic oil output from the second pump 5 and the third pump merges and enters the stick control valve 9, and controls the stick cylinder 21 to extend or retract through the stick control valve 9.

[0058] When the boom, stick, and bucket operate in combination, the first shut-off valve 12, the second shut-off valve 13, the third shut-off valve 14, and the fourth shut-off valve 15 are all in the connected position; the hydraulic oil output from the first pump 4 and the fourth pump enters the boom control valve 7, and controls the boom cylinder 18 to extend or retract through the boom control valve 7; the hydraulic oil output from the second pump 5 enters the stick control valve 9, and controls the stick cylinder 21 to extend or retract through the stick control valve 9; the hydraulic oil output from the third pump 6 enters the bucket control valve 11, and controls the bucket cylinder 23 to extend or retract through the bucket control valve 11.

[0059] (3) Explanation of the combined actions of getting on and off the vehicle.

[0060] Compared to the first embodiment, (a) for left travel: the second shut-off valve 13 operates in the connected position, ensuring that the power oil from the first pump 4 is only supplied to the left travel side; (b) for right travel: the working principle of the right travel side is the same as in embodiment one; (c) for the upper vehicle: the added fourth pump 27 supplies oil to the boom side, and the third pump 6 supplies oil to the stick side and the bucket side, at which time the fourth shut-off valve 15 operates in the connected position. Compared to the first embodiment, while the upper and lower vehicles are decoupled, the flow rate of the upper vehicle increases from a single pump to a dual pump flow rate, resulting in higher operating efficiency and better maneuverability.

[0061] The first shut-off valve 12 and the third shut-off valve 14 are both in the shut-off position, and the second shut-off valve 13 and the fourth shut-off valve 15 are both in the connected position. The hydraulic oil output from the first pump 4 enters the left travel control valve 8, and controls the left travel motor 19 to move forward or backward through the left travel control valve 8. The hydraulic oil output from the second pump 5 enters the right travel control valve 10, and controls the right travel motor 22 to move forward or backward through the right travel control valve 10. The hydraulic oil output from the third pump 6 enters the bucket control valve 11 and the stick control valve 9, and controls the bucket cylinder 23 and the stick cylinder 21 to extend or retract through the bucket control valve 11 and the stick control valve 9, respectively. The hydraulic oil output from the fourth pump enters the boom control valve 7, and controls the boom cylinder 18 to extend or retract through the boom control valve 7.

[0062] The hydraulic drive circuit proposed in this invention, after decoupling the actuator, can not only effectively improve the system energy efficiency, but also facilitate system debugging, improve the flexibility and operation performance of the whole machine; it reduces the control circuits related to linear travel and rotation, simplifies the structure of the hydraulic multi-way valve, and can adopt a modular design to reduce throttling energy loss and manufacturing costs.

[0063] Example 3:

[0064] Based on the excavator hydraulic drive system described in Embodiment 1 and Embodiment 2, this embodiment provides an excavator equipped with the excavator hydraulic drive system described in Embodiment 1 or Embodiment 2.

[0065] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A hydraulic drive system for an excavator, characterized in that, include: The first pump (4) has its outlet connected to the inlet of the boom control valve (7) via the first shut-off valve (12); the boom control valve (7) is used to drive the boom cylinder (18); the outlet of the first pump (4) is connected to the inlet of the left travel control valve (8), and the left travel control valve (8) is used to drive the left travel motor (19). The second pump (5) has its outlet connected to the inlet of the boom control valve (9) via a third shut-off valve (14); the boom control valve (9) is used to drive the boom cylinder (21); the outlet of the second pump (5) is connected to the inlet of the right travel control valve (10), which is used to drive the right travel motor (22). The third pump (6) has its outlet connected to the inlet of the bucket control valve (11), which is used to drive the bucket cylinder (23). The fourth motor (25) is used to drive the rotary reducer (26) to achieve rotary motion; The oil inlet of the boom control valve (7) is connected to the oil outlet of the third pump (6) through the second shut-off valve (13); the oil inlet of the stick control valve (9) is connected to the oil outlet of the third pump (6) through the fourth shut-off valve (15). When the loading and unloading actions are combined, the first shut-off valve (12) and the third shut-off valve (14) are both in the shut-off position, and the second shut-off valve (13) and the fourth shut-off valve (15) are both in the connected position; the hydraulic oil output by the first pump (4) enters the left travel control valve (8) and controls the left travel motor (19) to move forward or backward through the left travel control valve (8); the hydraulic oil output by the second pump (5) enters the right travel control valve (10) and controls the right travel motor (22) to move forward or backward through the right travel control valve (10); the hydraulic oil output by the third pump (6) enters the bucket control valve (11), the boom control valve (7) and the stick control valve (9) to control the bucket cylinder (23), the boom cylinder (18) and the stick cylinder (21) to extend or retract respectively; Alternatively, a fourth pump may be configured, in which case the oil inlet of the boom control valve (7) is connected to the oil outlet of the fourth pump through the second shut-off valve (13); and the oil inlet of the stick control valve (9) is connected to the oil outlet of the third pump (6) through the fourth shut-off valve (15). When the loading and unloading actions are combined, the first shut-off valve (12) and the third shut-off valve (14) are both in the shut-off position, and the second shut-off valve (13) and the fourth shut-off valve (15) are both in the connected position. The hydraulic oil output by the first pump (4) enters the left travel control valve (8) and controls the left travel motor (19) to move forward or backward through the left travel control valve (8). The hydraulic oil output by the second pump (5) enters the right travel control valve (10) and controls the right travel motor (22) to move forward or backward through the right travel control valve (10). The hydraulic oil output by the third pump (6) enters the bucket control valve (11) and the stick control valve (9) and controls the bucket cylinder (23) and the stick cylinder (21) to extend or retract through the bucket control valve (11) and the stick control valve (9) respectively. The hydraulic oil output by the fourth pump enters the boom control valve (7) and controls the boom cylinder (18) to extend or retract through the boom control valve (7).

2. The excavator hydraulic drive system according to claim 1, characterized in that, When the boom is raised in a single motion, the first shut-off valve (12) and the second shut-off valve (13) are both in the connected position. The hydraulic oil output from the first pump (4) and the third pump (6) merges and enters the boom control valve (7), and then enters the rodless chamber of the boom cylinder (18) through the boom control valve (7). The hydraulic oil in the rod chamber of the boom cylinder (18) enters the oil tank (24) through the return port of the boom control valve (7).

3. The excavator hydraulic drive system according to claim 1, characterized in that, When the fourth pump is configured, when the boom rises in a single action, the first shut-off valve (12) and the second shut-off valve (13) are both in the connected position. The hydraulic oil output from the first pump (4) and the fourth pump merges and enters the boom control valve (7), and then enters the rodless chamber of the boom cylinder (18) through the boom control valve (7). The hydraulic oil in the rod chamber of the boom cylinder (18) enters the oil tank (24) through the return port of the boom control valve (7).

4. The excavator hydraulic drive system according to claim 1, characterized in that, When the stick retracts or swings outward, the third shut-off valve (14) and the fourth shut-off valve (15) are both in the connected position. The hydraulic oil output from the second pump (5) and the third pump (6) merges and enters the stick control valve (9), and then enters the rodless chamber of the stick cylinder (21) through the stick control valve (9). The hydraulic oil in the rod chamber of the stick cylinder (21) enters the oil tank (24) through the return port of the stick control valve (9).

5. The excavator hydraulic drive system according to claim 1, characterized in that, When the bucket is in single action, the hydraulic oil output by the third pump (6) enters the bucket control valve (11) and enters the rod chamber or rodless chamber of the bucket cylinder (23) through the bucket control valve (11), thereby controlling the bucket cylinder (23) to achieve single action.

6. The excavator hydraulic drive system according to claim 1, characterized in that, When the left travel single action is performed, the hydraulic oil output by the first pump (4) enters the left travel control valve (8) and drives the left travel motor (19) through the left travel control valve (8).

7. The excavator hydraulic drive system according to claim 1, characterized in that, When the right travel single action is performed, the hydraulic oil output by the second pump (5) enters the right travel control valve (10) and drives the right travel motor (22) through the right travel control valve (10).

8. The excavator hydraulic drive system according to claim 1, characterized in that, When the boom and stick are in combined motion, the first shut-off valve (12), the third shut-off valve (14), and the fourth shut-off valve (15) are all in the connected position, and the second shut-off valve (13) is in the shut-off position. The hydraulic oil output by the first pump (4) enters the boom control valve (7) and controls the boom cylinder (18) to extend or retract through the boom control valve (7). The hydraulic oil output by the second pump (5) and the third pump (6) merges and enters the stick control valve (9), and controls the stick cylinder (21) to extend or retract through the stick control valve (9).

9. The excavator hydraulic drive system according to claim 1, characterized in that, When the fourth pump is configured, when the boom and stick are in combined motion, the first shut-off valve (12), the second shut-off valve (13), the third shut-off valve (14), and the fourth shut-off valve (15) are all in the connected position; the hydraulic oil output from the first pump (4) and the fourth pump enters the boom control valve (7) and controls the boom cylinder (18) to extend or retract through the boom control valve (7); the hydraulic oil output from the second pump (5) and the third pump (6) merges and enters the stick control valve (9), and controls the stick cylinder (21) to extend or retract through the stick control valve (9).

10. The excavator hydraulic drive system according to claim 1, characterized in that, When the boom, stick, and bucket are in combined motion, the first shut-off valve (12) and the third shut-off valve (14) are both in the connected position, and the second shut-off valve (13) and the fourth shut-off valve (15) are both in the shut-off position. The hydraulic oil output by the first pump (4) enters the boom control valve (7) and controls the boom cylinder (18) to extend or retract through the boom control valve (7). The hydraulic oil output by the second pump (5) enters the stick control valve (9) and controls the stick cylinder (21) to extend or retract through the stick control valve (9). The hydraulic oil output by the third pump (6) enters the bucket control valve (11) and controls the bucket cylinder (23) to extend or retract through the bucket control valve (11).

11. The excavator hydraulic drive system according to claim 1, characterized in that, When the fourth pump is configured, when the boom, stick, and bucket are in combined operation, the first shut-off valve (12), the second shut-off valve (13), the third shut-off valve (14), and the fourth shut-off valve (15) are all in the connected position; the hydraulic oil output from the first pump (4) and the fourth pump enters the boom control valve (7) and controls the boom cylinder (18) to extend or retract through the boom control valve (7); the hydraulic oil output from the second pump (5) enters the stick control valve (9) and controls the stick cylinder (21) to extend or retract through the stick control valve (9); the hydraulic oil output from the third pump (6) enters the bucket control valve (11) and controls the bucket cylinder (23) to extend or retract through the bucket control valve (11).

12. An excavator, characterized in that, The excavator is equipped with the excavator hydraulic drive system as described in any one of claims 1 to 11.

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