A load-sensitive hydraulic system for an excavator and an excavator

Abstract

This invention discloses a load-sensitive hydraulic system for an excavator and the excavator itself. The system includes: a main pump, the outlet of which is connected to the inlet of a main valve; the working ports of the main valve are respectively connected to the left travel motor, the right travel motor, and each working cylinder, for driving the left travel motor, the right travel motor, and each working cylinder; the LS port of the main valve for controlling the left travel motor and the LS port of the main valve for controlling the right travel motor converge in the LS1 oil circuit; the LS ports of the main valve for controlling each working cylinder are connected in series in the LS2 oil circuit, and after converging with the LS1 oil circuit at the first port of the main valve via a check valve, they are connected to the load feedback port PL of the main pump. This invention can force the main pump swashplate to be at the maximum tilt angle under pump power control when only the left / right travel motor is operating, increasing the output flow of the main pump, thereby ensuring that the entire machine can continuously travel in a straight line at a high speed.

Description

Technical Field

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

[0002] With the development of construction machinery, customers have raised new demands for the straight-line travel speed of excavators. For excavators using load-sensitive hydraulic systems, methods such as reducing pipeline pressure loss and increasing the volumetric efficiency of the hydraulic system are commonly used to increase the main pump output flow, thereby increasing the overall machine's straight-line travel speed. However, for load-sensitive hydraulic systems, due to pressure regulation fluctuations, the main pump swashplate angle may become less than the maximum angle under power control, making it impossible to continuously output at maximum displacement. This results in a decrease in the main pump output flow, thus failing to guarantee that the machine can continuously travel at a high speed in a straight line. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a load-sensitive hydraulic system and excavator that can forcibly maintain the main pump swashplate at the maximum tilt angle under pump power control when only the left / right travel motors are in operation, thereby increasing the main pump output flow and ensuring that the entire machine can continuously travel in a straight line at a high speed.

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

[0005] In a first aspect, a load-sensitive hydraulic system for an excavator is provided, comprising: a main pump, the outlet of which is connected to the inlet of a main valve; the working ports of the main valve are respectively connected to a left travel motor, a right travel motor, and a working cylinder, for driving the left travel motor, the right travel motor, and the working cylinder; wherein, the LS port of the main valve used to control the left travel linkage of the left travel motor and the LS port used to control the right travel linkage of the right travel motor converge in the LS1 oil circuit; the LS ports of the main valve used to control the working linkages of the working cylinders are connected in series in the LS2 oil circuit, and after converging with the LS1 oil circuit at the first port of the main valve via a check valve, are connected to the load feedback port PL of the main pump, for maintaining the swashplate of the main pump at the maximum tilt angle under pump power control when only the left / right travel motor is in operation, thereby increasing the output flow of the main pump.

[0006] Furthermore, it also includes a hydraulically controlled directional valve one, wherein the LS1 oil circuit is connected to port B of the hydraulically controlled directional valve one at the first connection of the main valve; the LS2 oil circuit is connected to the inlet of the check valve, and is also connected to port A of the hydraulically controlled directional valve one, the control end of the hydraulically controlled directional valve one, and the control end X of the hydraulically controlled directional valve two in the main pump.

[0007] Furthermore, the inlet Pp of the hydraulic directional valve II is connected to the outlet of the main pump, the outlet Pls of the hydraulic directional valve II is connected to the feedback port of the LS valve in the main pump, the return port Pt of the hydraulic directional valve II is connected to the oil tank, and the spring chamber of the LS valve is connected to the load feedback port PL of the main pump.

[0008] Furthermore, the LS2 oil circuit, after converging with the LS1 oil circuit at the first connection of the main valve, is connected to the load feedback port PL of the main pump via a one-way throttle valve.

[0009] Furthermore, when only the left / right travel motors are in operation, there is no feedback pressure in the LS2 oil circuit, and the hydraulic directional valve one is in the left position. Ports A and B of the hydraulic directional valve one are not connected. Due to the presence of the check valve, the travel-related feedback pressure in the LS1 oil circuit will not enter the control terminal X of the hydraulic directional valve two, nor will it enter the LS2 oil circuit. All the travel-related feedback pressure in the LS1 oil circuit acts on the spring chamber of the LS valve in the main pump through the load feedback port PL of the main pump. The hydraulic directional valve two is in the right position, and the outlet Pls of the hydraulic directional valve two is connected to the oil tank. At this time, the LS valve is in the right position and does not function, that is, it forcibly maintains the main pump swashplate at the maximum tilt angle under the pump power control, increasing the output flow of the main pump.

[0010] Furthermore, the working cylinder includes a bucket cylinder, a stick cylinder, and a boom cylinder; the first working port of the main valve is connected to the bucket cylinder, the second working port is connected to the stick cylinder, and the third working port is connected to the boom cylinder.

[0011] Furthermore, the working cylinder also includes a boom sway cylinder, and the fifth working port of the main valve is connected to the boom sway cylinder.

[0012] Furthermore, the working cylinder also includes a rotary motor, and the sixth working port in the main valve is connected to the rotary motor.

[0013] Furthermore, the working cylinder also includes a bulldozer cylinder, and the ninth working port of the main valve is connected to the bulldozer cylinder.

[0014] In a second aspect, an excavator is provided, the excavator being equipped with the excavator load-sensitive hydraulic system described in the first aspect.

[0015] Compared with the prior art, the beneficial effects achieved by the present invention are as follows: The present invention connects the LS oil port of the left travel link used to control the left travel motor and the LS oil port of the right travel link used to control the right travel motor in the main valve to the LS1 oil circuit; the LS oil ports of each working link used to control the working cylinder in the main valve are connected in series to the LS2 oil circuit, and after being connected to the load feedback port PL of the main pump through the check valve at the first connection of the main valve and the LS1 oil circuit, it can force the main pump swashplate to be kept at the maximum tilt angle under the pump power control when only the left / right travel motor is in operation, eliminate other influences, increase the output flow of the main pump, thereby ensuring that the whole machine can continuously travel in a straight line at a high speed without affecting the operation of other related actuators. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the principle of a load-sensitive hydraulic system for an excavator provided in an embodiment of the present invention;

[0017] Figure 2 yes Figure 1 A partial enlarged view of the main valve section;

[0018] Figure 3 yes Figure 1 A partially enlarged view of the main pump section;

[0019] In the diagram: 1. Main pump; 2. Main valve; 3. Bucket cylinder; 4. Stick cylinder; 5. Boom cylinder; 6. Hydraulic directional valve one; 7. Check valve; 8. Boom yaw cylinder; 9. Swing motor; 10. Left travel motor; 11. Right travel motor; 12. Bulldozer cylinder; 13. Center slewing body; 14. Oil tank; 15. Handle control unit; 16. Pilot pressure reducing unit; 17. Hydraulic directional valve two; 18. LS valve. Detailed Implementation

[0020] 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.

[0021] Example 1

[0022] like Figures 1-3 As shown, a load-sensitive hydraulic system for an excavator includes: a main pump 1, a main valve 2, working cylinders, a left travel motor 10, a right travel motor 11, and a central slewing body 13. The main pump 1 is a load-sensitive pump, and the main valve 2 is a load-sensitive valve. The working cylinders include a bucket cylinder 3, a stick cylinder 4, a boom cylinder 5, a boom yaw cylinder 8, a swing motor 9, and a bulldozing cylinder 12.

[0023] The outlet of the main pump 1 is connected to the inlet of the main valve 2. The working ports of the main valve 2 are respectively connected to the left travel motor 10, the right travel motor 11, and each working cylinder, for driving the left travel motor 10, the right travel motor 11, and each working cylinder. The main pump 1 draws oil from the oil tank 14. One of its outlet oil paths enters the pilot pressure reducing section 16, providing oil to the handle operating section 15; the other path enters the main valve through the P2 port of the main valve 2, supplying oil to the main oil circuit. The working ports A1~A9 and B1~B9 of the main valve 2 are connected to the corresponding actuator cylinder or motor ports. The pa1~pa9 and pb1~pb9 ports of the handle operating section 15 are correspondingly connected to the pilot ports of the main valve. When the pilot valve corresponding to the operating handle 15 is operated, the pressure at its pilot ports pa1~pa9 and pb1~pb9 pushes the corresponding valve core in the main valve 2 to move. At this time, the corresponding working ports A1~A9 and B1~B9 of the main valve 2 output pressure oil, which drives the actuator cylinder or motor to move, forming a load-sensitive oil circuit closed loop.

[0024] The first working port A1 / B1 of the main valve 2 is connected to the bucket cylinder 3; the second working port A2 / B2 is connected to the boom cylinder 4; the third working port A3 / B3 is connected to the boom cylinder 5; the fifth working port A5 / B5 is connected to the boom sway cylinder 8; the sixth working port A6 / B6 is connected to the swing motor 9; the seventh working port A7 / B7 is connected to the left travel motor 10; the eighth working port A8 / B8 is connected to the right travel motor 11; and the ninth working port A9 / B9 is connected to the bulldozer cylinder 12.

[0025] In this invention, the LS port oil circuits of each link of the main valve 2 are divided into two converging paths. The LS port oil circuit controlling the left travel motor 10 (the seventh link of the main valve 2) and the LS port oil circuit controlling the right travel motor 11 (the eighth link of the main valve 2) converge at the first link, i.e., the LS1 oil circuit. This circuit is also connected to port B of the hydraulic directional valve 6, which is a two-position, two-way hydraulic directional valve. The LS ports of all other working links of the main valve 2, except those controlling the two travel motors, are connected in series to the LS2 oil circuit. After passing through the check valve 7, they converge at the first link of the main valve 2 with the aforementioned LS1 oil circuit. The converged LS oil circuit then passes through a one-way throttle valve and connects to the load feedback port PL of the main pump 1, forming a closed-loop system. The main pump 1 is equipped with a two-position, three-way hydraulic directional valve 17. Its inlet Pp is connected to the oil outlet of the main pump 1, its outlet Pls is connected to the feedback port of the LS valve 18 in the main pump, and its return port Pt is connected to the oil tank 14. Its control terminal X is connected to the LS2 oil circuit and is located before the check valve 7. The B port of the hydraulic directional valve 6 is connected to the LS1 oil circuit, and its A port is connected to the LS2 oil circuit. It is located before the check valve 7, and its control terminal is connected to the A port oil circuit, which is connected to the LS2 oil circuit.

[0026] When only the left / right travel motors are active, due to the presence of the one-way valve 7, there is no relevant pressure in the LS2 oil circuit, while the LS1 oil circuit experiences travel-related feedback pressure. The control terminal of the hydraulic directional valve 6 is connected to the LS2 oil circuit, and it is in the left position. At this time, the LS1 and LS2 oil circuits are not connected; the feedback pressure from the LS1 oil circuit acts on the right-side spring chamber of the LS valve 18 of the main pump 1 through the one-way throttle valve and the load feedback port PL of the main pump 1. The control terminal X of the hydraulic directional valve 17 is in the right position with no pressure, and its outlet Pls is connected to the oil tank 14. At this time, the LS valve 18 of the main pump 1 is in the right position and does not function, thus forcibly maintaining the main pump swashplate at the maximum tilt angle under pump power control, eliminating other influences, increasing the main pump output flow, and ensuring the entire machine can continuously travel in a straight line at a high speed.

[0027] When other cylinders / motors operate (including the travel motor), the main valve LS2 oil circuit is pressurized, and the hydraulic directional valve 6 switches to the right position. This connects the LS1 and LS2 oil circuits, and through the one-way throttle valve, acts on the right side of the LS valve in the main pump. Meanwhile, the control terminal X of the hydraulic directional valve 17 is connected to the LS2 oil circuit, meaning it is in the left position. This is the same as the aforementioned load-sensitive oil circuit closed loop.

[0028] In summary, when only the left / right travel motors are activated, this invention can forcibly maintain the main pump swashplate at the maximum tilt angle under pump power control, increasing the output flow rate under travel-only conditions and improving the overall machine travel speed. Furthermore, when other cylinders / motors are activated (including the travel motors), the load-sensitive control of each action is restored, without affecting its maneuverability (the remaining components are conventional hydraulic components and will not be described further here).

[0029] Example 2

[0030] Based on the excavator load-sensitive hydraulic system described in Embodiment 1, this embodiment provides an excavator equipped with the excavator load-sensitive hydraulic system described in Embodiment 1.

[0031] 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 load-sensitive hydraulic system for an excavator, characterized in that, include: The main pump (1) has its outlet connected to the inlet of the main valve (2). The working ports of the main valve (2) are connected to the left travel motor (10), the right travel motor (11) and each working cylinder, respectively, for driving the left travel motor (10), the right travel motor (11) and each working cylinder to work. Among them, the LS oil port of the main valve (2) used to control the left travel link of the left travel motor (10) and the LS oil port used to control the right travel link of the right travel motor (11) are connected to the LS1 oil circuit; the LS oil ports of the main valve (2) used to control each working link of the working cylinder are connected in series to the LS2 oil circuit, and are connected to the load feedback port PL of the main pump (1) after being connected to the first link of the main valve (2) and the LS1 oil circuit via the check valve (7). This is used to keep the swashplate of the main pump at the maximum tilt angle under the pump power control when only the left / right travel motor is in motion, thereby increasing the output flow of the main pump (1).

2. The excavator load-sensitive hydraulic system according to claim 1, characterized in that, It also includes a hydraulically controlled directional valve one (6), the LS1 oil circuit is connected to the B port of the hydraulically controlled directional valve one (6) at the first connection of the main valve (2); the LS2 oil circuit is connected to the inlet of the check valve (7), and is also connected to the A port of the hydraulically controlled directional valve one (6), the control end of the hydraulically controlled directional valve one (6), and the control end X of the hydraulically controlled directional valve two (17) in the main pump (1).

3. The excavator load-sensitive hydraulic system according to claim 2, characterized in that, The inlet Pp of the hydraulic directional valve 2 (17) is connected to the outlet of the main pump (1), the outlet Pls of the hydraulic directional valve 2 (17) is connected to the feedback port of the LS valve in the main pump (1), the return port Pt of the hydraulic directional valve 2 (17) is connected to the oil tank (14), and the spring chamber of the LS valve is connected to the load feedback port PL of the main pump (1).

4. The excavator load-sensitive hydraulic system according to claim 3, characterized in that, The LS2 oil circuit is connected to the load feedback port PL of the main pump (1) through a one-way throttle valve after it merges with the LS1 oil circuit at the first connection of the main valve (2).

5. The excavator load-sensitive hydraulic system according to claim 4, characterized in that, When only the left / right travel motor is in motion, there is no feedback pressure in the LS2 oil circuit. The hydraulic control directional valve one (6) is in the left position. The A port and B port of the hydraulic control directional valve one (6) are not connected. Due to the presence of the check valve (7), the travel-related feedback pressure in the LS1 oil circuit will not enter the control terminal X of the hydraulic control directional valve two (17) nor will it enter the LS2 oil circuit. All the travel-related feedback pressure in the LS1 oil circuit acts on the spring chamber of the LS valve in the main pump (1) through the load feedback port PL of the main pump (1). The hydraulic control directional valve two (17) is in the right position. The outlet Pls of the hydraulic control directional valve two (17) is connected to the oil tank (14). At this time, the LS valve is in the right position and the LS valve does not work. That is, it forces the main pump swashplate to be in the maximum tilt angle under the pump power control, which increases the output flow of the main pump (1).

6. The excavator load-sensitive hydraulic system according to claim 1, characterized in that, The working cylinders include a bucket cylinder (3), a stick cylinder (4), and a boom cylinder (5); the first working port of the main valve (2) is connected to the bucket cylinder (3), the second working port is connected to the stick cylinder (4), and the third working port is connected to the boom cylinder (5).

7. The excavator load-sensitive hydraulic system according to claim 1, characterized in that, The working cylinder also includes a boom sway cylinder (8), and the fifth working port of the main valve (2) is connected to the boom sway cylinder (8).

8. The excavator load-sensitive hydraulic system according to claim 1, characterized in that, The working cylinder also includes a rotary motor (9), and the sixth working port of the main valve (2) is connected to the rotary motor (9).

9. The excavator load-sensitive hydraulic system according to claim 1, characterized in that, The working cylinder also includes a bulldozer cylinder (12), and the ninth working port of the main valve (2) is connected to the bulldozer cylinder (12).

10. An excavator, characterized in that, The excavator is equipped with the excavator load-sensitive hydraulic system as described in any one of claims 1 to 9.

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