Excavator air suction prevention hydraulic system and method and excavator

Abstract

The hydraulic system comprises an oil tank, a pilot pump, a pilot valve, a main control valve and an automatic oil supplementing valve, the pilot pump is provided with a pilot pump oil inlet and a pilot pump oil outlet, the pilot pump oil inlet is communicated with the oil tank, and the pilot pump oil outlet is communicated with the main control valve. The pilot valve is provided with a pilot valve first oil outlet, a pilot valve second oil outlet, a pilot valve oil inlet and a pilot valve oil return opening, the pilot valve oil return opening is communicated with the oil tank, the main control valve is provided with a main control valve first oil opening and a main control valve second oil opening, the pilot valve first oil outlet is communicated with the main control valve first oil opening, and the pilot valve second oil outlet is communicated with the main control valve second oil opening. The first oil outlet of the pilot valve is communicated with the first oil port of the main control valve, the second oil outlet of the pilot valve is communicated with the second oil port of the main control valve, the automatic oil supplementing valve is provided with a first oil supplementing valve oil port, a second oil supplementing valve oil port and a third oil supplementing valve oil port, and the third oil supplementing valve oil port is communicated with the oil tank. Automatic oil supplement of the main control valve is achieved, and the phenomenon of air suction caused by negative pressure is prevented.

Description

Technical Field

[0001] The present invention relates to the technical field of excavators, and in particular to an excavator anti-cavitation hydraulic system, method and excavator. Background Art

[0002] In the prior art, the hydraulic system of an excavator is the core control and motion system for realizing the compound actions of the excavator. It supplies oil to the main control valve through the main pump, and then the main control valve supplies oil to various actuators (such as cylinders and motors) through the valve core reversing, so as to complete complex operations such as excavation and loading. Since the valve core of the hydraulic valve requires a large driving force to move, a pilot valve is usually used to output hydraulic oil for driving. The pilot valve is generally arranged in the cab and is supplied with oil by a pilot pump installed in the same position as the main pump. When the driver operates the pilot handle, the pilot valve will output hydraulic oil to the main valve to control its action.

[0003] However, for ultra-large excavators, due to the huge size of the machine body, the location of the cab is often higher and farther than the main valve and oil tank. This layout leads to a significantly longer pilot oil transmission path from the cab to the main valve. In this case, the following problems are prone to occur after the pilot oil is transmitted over a long distance:

[0004] Under long-term or frequent operation, the pilot oil may form cavitation in the pipeline, or in compound actions, the pilot valve needs to be shared by multiple valve cores at the same time, and a large amount of oil needs to be replenished when the valve core is reset, which will also cause cavitation. After the cavitation occurs, due to the long transmission path, the time required for the pilot oil to reach the destination increases, making the speed of building pressure slower, which directly affects the response speed of the entire hydraulic system. At the same time, in the case of cavitation and low efficiency of pilot oil pressure building, the action of the valve core becomes less sensitive and the response time is prolonged, resulting in a decrease in the operating performance of the entire excavator, especially in situations where a quick response is required. Summary of the invention

[0005] In order to overcome at least one defect of the above-mentioned prior art, the present invention provides an excavator anti-cavitation hydraulic system, method and excavator, which can solve the problems of cavitation caused by a long pilot oil circuit, slow pressure buildup and slow response speed of the main control valve core.

[0006] The technical solution adopted by the present invention to solve the problem is:

[0007] An anti-cavitation hydraulic system for an excavator, comprising:

[0008] tank;

[0009] A pilot pump, wherein the pilot pump has a pilot pump oil inlet and a pilot pump oil outlet, and the pilot pump oil inlet is connected to the oil tank;

[0010] A pilot valve, wherein the pilot valve has a first pilot valve oil outlet, a second pilot valve oil outlet, a pilot valve oil inlet and a pilot valve oil return port, the pilot valve oil inlet is connected to the pilot pump oil outlet, and the pilot valve oil return port is connected to the oil tank;

[0011] A main control valve, wherein the main control valve has a first oil port and a second oil port of the main control valve, wherein the first oil port and the second oil port of the main control valve are respectively arranged at two ends of the valve core movement direction of the main control valve, so that after the first oil port of the main control valve obtains oil, the valve core of the main control valve is driven to slide toward the second oil port of the main control valve, and after the second oil port of the main control valve obtains oil, the valve core of the main control valve is driven to slide toward the first oil port of the main control valve, the first oil outlet of the pilot valve is communicated with the first oil port of the main control valve, and the second oil outlet of the pilot valve is communicated with the second oil port of the main control valve;

[0012] An automatic oil replenishing valve, wherein the automatic oil replenishing valve has a first oil port, a second oil port and a third oil port, and the third oil port of the oil replenishing valve is connected to the oil tank;

[0013] When the first oil port of the main control valve is in a negative pressure state, the automatic oil replenishing valve switches to the first oil port of the oil replenishing valve to communicate with the third oil port of the oil replenishing valve, so that the negative pressure state of the first oil port of the main control valve can draw hydraulic oil from the oil tank and pour it into the main control valve in sequence through the third oil port of the oil replenishing valve and the first oil port of the main control valve;

[0014] When the second oil port of the main control valve is in a negative pressure state, the automatic oil replenishing valve switches to the second oil port of the oil replenishing valve and connects with the third oil port of the oil replenishing valve, so that the negative pressure state of the second oil port of the main control valve can draw hydraulic oil from the oil tank and pour it into the main control valve in sequence through the third oil port of the oil replenishing valve and the second oil port of the main control valve.

[0015] Further, the automatic oil replenishing valve is an anti-cavitation valve, which has a first oil port, a second oil port, a third oil port, a fourth oil port and a fifth oil port. The first oil port of the anti-cavitation valve is the first oil port of the oil replenishing valve, the second oil port of the anti-cavitation valve is the second oil port of the oil replenishing valve, and the third oil port of the anti-cavitation valve is the third oil port of the oil replenishing valve. The first oil port, the second oil port and the third oil port of the anti-cavitation valve are in a connected state. The fourth oil port and the fifth oil port of the anti-cavitation valve are respectively located at two ends of the valve core movement direction of the anti-cavitation valve, so that after the fourth oil port of the anti-cavitation valve obtains oil, the valve core of the anti-cavitation valve is driven to slide toward the fifth oil port of the anti-cavitation valve, and after the fifth oil port of the anti-cavitation valve obtains oil, the valve core of the anti-cavitation valve is driven to slide toward the fourth oil port of the anti-cavitation valve.

[0016] Further, the pilot valve is controlled by a pilot handle, and the pilot valve has an initial state, a first state and a second state;

[0017] The initial state of the pilot valve is that the first oil outlet of the pilot valve and the second oil outlet of the pilot valve are both in a cut-off state, the first oil outlet of the anti-cavitation valve is connected to the first oil outlet of the main control valve through the first oil circuit, the second oil outlet of the anti-cavitation valve is connected to the second oil outlet of the main control valve through the second oil circuit, and the third oil outlet of the anti-cavitation valve is connected to the oil tank through the third oil circuit;

[0018] The first state of the pilot valve is a state in which the oil inlet of the pilot valve and the first oil outlet of the pilot valve are connected, the first oil outlet of the pilot valve supplies oil to the fourth oil port of the anti-cavitation valve to push the valve core of the anti-cavitation valve to slide toward the fifth oil port of the anti-cavitation valve, after the valve core of the anti-cavitation valve completes sliding, the pilot valve is connected to the first oil port of the main control valve through the first oil circuit, the first oil port of the main control valve obtains oil to push the valve core of the main control valve to slide toward the second oil port of the main control valve, completing the sliding switching of the valve core of the main control valve from the first oil port of the main control valve to the second oil port of the main control valve, and the return oil of the main control valve flows from the second oil port of the main control valve through the pilot valve into the oil tank;

[0019] The second state of the pilot valve is a conductive state between the oil inlet of the pilot valve and the second oil outlet of the pilot valve, the second oil outlet of the pilot valve supplies oil to the fifth oil port of the anti-cavitation valve to push the valve core of the anti-cavitation valve to slide toward the fourth oil port of the anti-cavitation valve, after the valve core of the anti-cavitation valve completes sliding, the pilot valve is connected with the second oil port of the main control valve through the first oil circuit, the second oil port of the main control valve pushes the valve core of the main control valve to slide toward the first oil port of the main control valve, completing the sliding switching of the valve core of the main control valve from the second oil port of the main control valve to the first oil port of the main control valve, and the return oil of the main control valve flows from the first oil port of the main control valve through the pilot valve into the oil tank.

[0020] Further, when the pilot valve switches to the initial state, the anti-cavitation valve automatically resets to the point where the first oil port of the anti-cavitation valve is connected to the first oil circuit, the second oil port of the anti-cavitation valve is connected to the second oil circuit, and the third oil port of the anti-cavitation valve is connected to the third oil circuit.

[0021] Furthermore, it also includes a main pump and an oil cylinder, the main pump having a main pump oil inlet and a main pump oil outlet, the main pump oil inlet is connected to the oil tank, the main pump oil outlet is connected to the main control valve, and the oil cylinder and the main pump are connected through the main control valve to control the flow direction of the oil out of the main pump oil outlet.

[0022] The present invention also provides a method for preventing cavitation of an excavator hydraulic system, using the above-mentioned anti-cavitation hydraulic system for an excavator;

[0023] When the valve core of the main control valve is close to the first oil port of the main control valve and the first oil port of the main control valve is in a negative pressure state during the resetting process of the main control valve, the automatic oil replenishing valve is switched to the first oil port of the oil replenishing valve to communicate with the third oil port of the oil replenishing valve, so that the negative pressure state of the first oil port of the main control valve can draw hydraulic oil from the oil tank and pour it into the main control valve in sequence through the third oil port of the oil replenishing valve and the first oil port of the main control valve;

[0024] When the valve core of the main control valve is close to the second oil port of the main control valve and the second oil port of the main control valve is in a negative pressure state during the resetting process of the main control valve, the automatic oil replenishing valve is switched to the second oil port of the oil replenishing valve to be connected with the third oil port of the oil replenishing valve, so that the negative pressure state of the second oil port of the main control valve can draw hydraulic oil from the oil tank and pour it into the main control valve through the third oil port of the oil replenishing valve and the second oil port of the main control valve in sequence.

[0025] The present invention also provides an excavator, comprising the above-mentioned excavator anti-cavitation hydraulic system.

[0026] In summary, the anti-cavitation hydraulic system, method and excavator provided by the present invention have the following technical effects:

[0027] 1. When the first oil port of the main control valve is in a negative pressure state, the first oil port of the automatic oil replenishment valve is connected to the third oil port of the oil replenishment valve, so that the first oil port of the main control valve can directly draw hydraulic oil from the oil tank and pour it into the main control valve through the third oil port of the oil replenishment valve and the first oil port of the main control valve. Similarly, when the second oil port of the main control valve is in a negative pressure state, the second oil port of the automatic oil replenishment valve is connected to the third oil port of the oil replenishment valve, so that the second oil port of the main control valve can draw hydraulic oil from the oil tank and pour it into the main control valve through the third oil port of the oil replenishment valve and the second oil port of the main control valve. This mechanism effectively prevents the cavitation phenomenon caused by negative pressure and ensures the stability and reliability of the hydraulic system;

[0028] 2. When negative pressure occurs at the first oil port or the second oil port of the main control valve, it is no longer necessary to replenish the main control valve through the pilot valve, which greatly shortens the circuit length and reduces unnecessary oil transmission paths, thereby greatly increasing the speed at which the pilot oil reaches the main control valve, thereby speeding up the pressure building process. The faster the pressure building speed, the faster the action response of the main control valve core, and the better the response time of the entire hydraulic system;

[0029] 3. The anti-cavitation design ensures that the hydraulic oil can be filled into the first oil port of the main control valve or the second oil port of the main control valve in time, avoiding the slow movement problem caused by bubbles or partial vacuum. It not only improves the movement speed of the main control valve core, but also enhances the accuracy of its operation, greatly improving the overall control performance of the excavator. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic diagram of the hydraulic system of Example 1 of the present invention.

[0031] Among them, the meanings of the accompanying drawings are as follows: 1. oil tank; 2. pilot pump; 21. pilot pump oil inlet; 22. pilot pump oil outlet; 3. pilot valve; 31. first oil outlet of pilot valve; 32. second oil outlet of pilot valve; 33. oil inlet of pilot valve; 34. oil return port of pilot valve; 4. main control valve; 41. first oil port of main control valve; 42. second oil port of main control valve; 5. anti-cavitation valve; 51. first oil port of anti-cavitation valve; 52. second oil port of anti-cavitation valve; 53. third oil port of anti-cavitation valve; 54. fourth oil port of anti-cavitation valve; 55. fifth oil port of anti-cavitation valve; 6. main pump; 61. main pump oil inlet; 62. main pump oil outlet; 7. oil cylinder; 81. first oil circuit; 82. second oil circuit; 83. third oil circuit. DETAILED DESCRIPTION

[0032] For better understanding and implementation, the technical solutions in the embodiments of the present invention will be clearly and completely described and discussed below in conjunction with the accompanying drawings of the present invention. Obviously, what is described here is only a part of the examples of the present invention, not all the examples. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0033] In order to facilitate the understanding of the embodiments of the present invention, the following will be further explained by taking specific embodiments as examples in conjunction with the drawings, and each embodiment does not constitute a limitation on the embodiments of the present invention.

[0034] In the description of the present invention, it should be noted that the terms "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the present invention.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing specific embodiments and are not intended to limit the present invention.

[0036] See also Figure 1 The present invention discloses an anti-cavitation hydraulic system for an excavator, comprising an oil tank 1, a pilot pump 2, a pilot valve 3, a main control valve 4 and an automatic oil replenishing valve, wherein the pilot pump 2 has a pilot pump oil inlet 21 and a pilot pump oil outlet 22, and the pilot pump oil inlet 21 is connected to the oil tank 1. The pilot valve 3 has a first pilot valve oil outlet 31, a second pilot valve oil outlet 32, a pilot valve oil inlet 33 and a pilot valve oil return port 34, wherein the pilot valve oil inlet 33 is connected to the pilot pump oil outlet 22, and the pilot valve oil return port 34 is connected to the oil tank 1. The main control valve 4 has a first oil port 41 and a second oil port 42 of the main control valve, which are respectively arranged at the two ends of the valve core movement direction of the main control valve 4, so that the first oil port 41 of the main control valve drives the valve core of the main control valve 4 to slide toward the second oil port 42 of the main control valve after the first oil port 41 of the main control valve obtains oil, and the second oil port 42 of the main control valve drives the valve core of the main control valve 4 to slide toward the first oil port 41 of the main control valve after the second oil port 42 of the main control valve obtains oil. The first oil outlet 31 of the pilot valve is connected to the first oil port 41 of the main control valve, and the second oil outlet 32 ​​of the pilot valve is connected to the second oil port 42 of the main control valve. The automatic oil replenishment valve has a first oil port, a second oil port and a third oil port of the oil replenishment valve, and the third oil port of the oil replenishment valve is connected to the oil tank 1. When the first oil port 41 of the main control valve is in a negative pressure state, the automatic oil replenishing valve switches to the first oil port of the oil replenishing valve and communicates with the third oil port of the oil replenishing valve, so that the negative pressure state of the first oil port 41 of the main control valve can draw hydraulic oil from the oil tank 1 and pour it into the main control valve 4 through the third oil port of the oil replenishing valve and the first oil port 41 of the main control valve in sequence. When the second oil port 42 of the main control valve is in a negative pressure state, the automatic oil replenishing valve switches to the second oil port of the oil replenishing valve and communicates with the third oil port of the oil replenishing valve, so that the negative pressure state of the second oil port 42 of the main control valve can draw hydraulic oil from the oil tank 1 and pour it into the main control valve 4 through the third oil port of the oil replenishing valve and the second oil port 42 of the main control valve in sequence.

[0037] Specifically, the oil tank 1 serves as an oil storage device of the hydraulic system, provides hydraulic oil for the entire hydraulic system, and receives hydraulic oil returned from each component. The pilot pump 2 has a pilot pump oil inlet 21 and a pilot pump oil outlet 22, and the pilot pump oil inlet 21 is connected to the oil tank 1 to ensure that the hydraulic oil can be continuously extracted. The pilot valve 3 is provided with a pilot valve first oil outlet 31, a pilot valve second oil outlet 32, a pilot valve oil inlet 33 and a pilot valve oil return port 34. The pilot valve oil return port 34 is directly connected to the oil tank 1. The pilot valve first oil outlet 31 and the pilot valve second oil outlet 32 ​​are respectively connected to the main control valve first oil port 41 and the main control valve second oil port 42, and are used to control the valve core of the main control valve 4 to move between the main control valve first oil port 41 and the main control valve second oil port 42 at both ends according to the flow direction of the hydraulic oil. When the first oil port 41 of the main control valve receives oil, the valve core is driven to slide toward the second oil port 42 of the main control valve; conversely, when the second oil port 42 of the main control valve receives oil, the valve core is driven to slide toward the first oil port 41 of the main control valve. The main control valve 4 operates the actuator (such as the oil cylinder 7, the motor, etc.) by controlling the flow direction of the hydraulic oil to complete the actions of excavation and loading. The automatic oil replenishing valve has the first oil port of the oil replenishing valve, the second oil port of the oil replenishing valve and the third oil port of the oil replenishing valve, wherein the third oil port of the oil replenishing valve is connected to the oil tank 1. When the first oil port 41 of the main control valve is in a negative pressure state, the automatic oil replenishing valve switches to the first oil port of the oil replenishing valve and is connected to the third oil port of the oil replenishing valve, so that the first oil port 41 of the main control valve can draw hydraulic oil from the oil tank 1 and pour it into the main control valve 4 through the third oil port of the oil replenishing valve and the first oil port 41 of the main control valve in sequence. Similarly, when the second oil port 42 of the main control valve is in a negative pressure state, the automatic oil replenishing valve switches to connect the second oil port of the oil replenishing valve with the third oil port of the oil replenishing valve, so that the second oil port 42 of the main control valve can draw hydraulic oil from the oil tank 1 and inject it into the main control valve 4 in sequence through the third oil port of the oil replenishing valve and the second oil port 42 of the main control valve.

[0038] Among them, the automatic oil replenishing valve can be a solenoid valve or an anti-cavitation valve 5. When the automatic oil replenishing valve is a solenoid valve, a sensor for monitoring the air pressure can be set near the first oil port 41 of the main control valve and the second oil port 42 of the main control valve. When a negative pressure state is detected, the first oil port of the oil replenishing valve, the second oil port of the oil replenishing valve or the third oil port of the oil replenishing valve corresponding to the threshold value can be connected.

[0039] When the automatic oil replenishing valve adopts the anti-cavitation valve 5, the anti-cavitation valve 5 has a first oil port 51 of the anti-cavitation valve, a second oil port 52 of the anti-cavitation valve, a third oil port 53 of the anti-cavitation valve, a fourth oil port 54 of the anti-cavitation valve and a fifth oil port 55 of the anti-cavitation valve. The first oil port 51 of the anti-cavitation valve is the first oil port of the oil replenishing valve, the second oil port 52 of the anti-cavitation valve is the second oil port of the oil replenishing valve, the third oil port 53 of the anti-cavitation valve is the third oil port of the oil replenishing valve, and the first oil port 51 of the anti-cavitation valve, the second oil port 52 of the anti-cavitation valve, the third oil port 53 of the anti-cavitation valve, the fourth oil port 54 of the anti-cavitation valve and the fifth oil port 55 of the anti-cavitation valve. The second oil port 52 of the cavitation valve and the third oil port 53 of the anti-cavitation valve are in a connected state, and the fourth oil port 54 of the anti-cavitation valve and the fifth oil port 55 of the anti-cavitation valve are respectively located at two ends of the valve core movement direction of the anti-cavitation valve 5, so that the fourth oil port 54 of the anti-cavitation valve drives the valve core of the anti-cavitation valve 5 to slide toward the fifth oil port 55 of the anti-cavitation valve after receiving oil, and the fifth oil port 55 of the anti-cavitation valve drives the valve core of the anti-cavitation valve 5 to slide toward the fourth oil port 54 of the anti-cavitation valve after receiving oil.

[0040] Specifically, the anti-cavitation valve 5 has a first oil port 51, a second oil port 52, a third oil port 53, a fourth oil port 54 and a fifth oil port 55. The first oil port 51 is the first oil port of the replenishing valve, the second oil port 52 corresponds to the second oil port of the replenishing valve, and the third oil port 53 corresponds to the third oil port of the replenishing valve.

[0041] The first oil port 51 of the anti-cavitation valve, the second oil port 52 of the anti-cavitation valve and the third oil port 53 of the anti-cavitation valve are in a connected state. When a negative pressure state appears in the first oil port 41 or the second oil port 42 of the main control valve, it is mainly because the valve core of the main control valve 4 is in a reset or switching state. During the switching process of the corresponding valve core of the main control valve 4, the valve core of the main control valve 4 also needs to pass through the reset position of the valve core of the main control valve 4. The valve core of the main control valve will only produce a negative pressure in the first oil port 41 or the second oil port 42 of the main control valve when it is in a reset or switching state. In this state, the anti-cavitation valve 5 will also be reset. In this state, the first oil port 51, the second oil port 52 and the third oil port 53 of the anti-cavitation valve are in a connected state, thereby ensuring that when a negative pressure state appears in the first oil port 41 or the second oil port 42 of the main control valve, hydraulic oil can be quickly obtained from the oil tank 1 for replenishment. The fourth oil port 54 of the anti-cavitation valve and the fifth oil port 55 of the anti-cavitation valve are respectively located at two ends of the valve core movement direction of the anti-cavitation valve 5, so that after the fourth oil port 54 of the anti-cavitation valve receives oil, the valve core of the anti-cavitation valve 5 is driven to slide toward the fifth oil port 55 of the anti-cavitation valve, and vice versa.

[0042] Further, the pilot valve 3 is controlled by a pilot handle, and the pilot valve 3 has an initial state, a first state and a second state;

[0043] The initial state of the pilot valve 3 is that the first oil outlet 31 and the second oil outlet 32 ​​of the pilot valve are both in a cut-off state, the first oil outlet 51 of the anti-cavitation valve is connected to the first oil outlet 41 of the main control valve through the first oil passage 81, the second oil outlet 52 of the anti-cavitation valve is connected to the second oil outlet 42 of the main control valve through the second oil passage 82, and the third oil outlet 53 of the anti-cavitation valve is connected to the oil tank 1 through the third oil passage 83;

[0044] The first state of the pilot valve 3 is the state in which the pilot valve oil inlet 33 and the pilot valve first oil outlet 31 are connected, the pilot valve first oil outlet 31 supplies oil to the anti-cavitation valve fourth oil port 54 to push the valve core of the anti-cavitation valve 5 to slide toward the anti-cavitation valve fifth oil port 55, after the valve core of the anti-cavitation valve 5 completes sliding, the pilot valve 3 is connected with the main control valve first oil port 41 through the first oil path 81, the main control valve first oil port 41 obtains oil to push the valve core of the main control valve 4 to slide toward the main control valve second oil port 42, completing the sliding switching of the valve core of the main control valve 4 from the main control valve first oil port 41 to the main control valve second oil port 42, and the return oil of the main control valve 4 flows from the main control valve second oil port 42 through the pilot valve 3 into the oil tank 1;

[0045] The second state of the pilot valve 3 is the conducting state of the pilot valve oil inlet 33 and the pilot valve second oil outlet 32, the pilot valve second oil outlet 32 ​​supplies oil to the anti-cavitation valve fifth oil port 55 to push the valve core of the anti-cavitation valve 5 to slide toward the fourth oil port 54 of the anti-cavitation valve, after the valve core of the anti-cavitation valve 5 completes sliding, the pilot valve 3 is connected with the main control valve second oil port 42 through the first oil path 81, the main control valve second oil port 42 pushes the valve core of the main control valve 4 to slide toward the main control valve first oil port 41, completing the sliding switching of the valve core of the main control valve 4 from the main control valve second oil port 42 to the main control valve first oil port 41, and the return oil of the main control valve 4 flows from the main control valve first oil port 41 through the pilot valve 3 into the oil tank 1.

[0046] Specifically, the pilot valve 3 is provided with a first pilot valve oil outlet 31, a second pilot valve oil outlet 32, a pilot valve oil inlet 33 and a pilot valve oil return port 34. The pilot valve 3 is controlled by a pilot handle and has the following three states:

[0047] Initial state: the first oil outlet and the second oil outlet of the pilot valve 3 are both in the cut-off state. At this time, the first oil port 51 of the anti-cavitation valve is connected to the first oil port 41 of the main control valve through the first oil circuit 81, the second oil port 52 of the anti-cavitation valve is connected to the second oil port 42 of the main control valve through the second oil circuit 82, and the third oil port 53 of the anti-cavitation valve is connected to the oil tank 1 through the third oil circuit 83. In this state, it is ensured that no matter the first oil port 41 of the main control valve or the second oil port 42 of the main control valve is in a negative pressure state, hydraulic oil can be immediately drawn from the oil tank 1 for replenishment to prevent the occurrence of cavitation.

[0048] First state: When the driver operates the pilot handle to make the pilot valve 3 enter the first state, the pilot valve oil inlet 33 and the pilot valve first oil outlet 31 are connected. The pilot valve first oil outlet 31 supplies oil to the anti-cavitation valve fourth oil port 54, pushing the valve core of the anti-cavitation valve 5 to slide toward the anti-cavitation valve fifth oil port 55. After the valve core of the anti-cavitation valve 5 completes sliding, the hydraulic oil is connected to the main control valve first oil port 41 through the first oil path 81. After the main control valve first oil port 41 receives oil, it pushes the valve core of the main control valve 4 to slide toward the main control valve second oil port 42, completing the sliding switch of the valve core of the main control valve 4 from the main control valve first oil port 41 to the main control valve second oil port 42. The return oil of the main control valve 4 flows from the main control valve second oil port 42 through the pilot valve 3 into the oil tank 1, ensuring the effective circulation of the hydraulic oil and the stable operation of the system.

[0049] Second state: When the driver operates the pilot handle to make the pilot valve 3 enter the second state, the pilot valve oil inlet 33 and the pilot valve second oil outlet 32 ​​are connected. The pilot valve second oil outlet 32 ​​supplies oil to the anti-cavitation valve fifth oil port 55, pushing the valve core of the anti-cavitation valve 5 to slide toward the anti-cavitation valve fourth oil port 54. After the valve core of the anti-cavitation valve 5 completes sliding, the hydraulic oil is connected to the main control valve second oil port 42 through the second oil path 82. After the main control valve second oil port 42 receives oil, it pushes the valve core of the main control valve 4 to slide toward the main control valve first oil port 41, completing the sliding switch of the valve core of the main control valve 4 from the main control valve second oil port 42 to the main control valve first oil port 41. The return oil of the main control valve 4 flows from the main control valve first oil port 41 through the pilot valve 3 into the oil tank 1, ensuring the effective circulation of the hydraulic oil and the stability of the system.

[0050] In some embodiments, when the pilot valve 3 switches to the initial state, the anti-cavitation valve 5 automatically resets to the point where the first oil port 51 of the anti-cavitation valve is connected to the first oil circuit 81, the second oil port 52 of the anti-cavitation valve is connected to the second oil circuit 82, and the third oil port 53 of the anti-cavitation valve is connected to the third oil circuit 83.

[0051] Specifically, when the driver releases the pilot handle or puts it in the neutral position, the first oil outlet and the second oil outlet of the pilot valve 3 are cut off, and no oil is supplied to the fourth oil port or the fifth oil port of the anti-cavitation valve 5. The pilot valve 3 switches to the initial state, in which the pilot valve 3 stops pushing the valve core of the anti-cavitation valve 5, allowing the valve core of the anti-cavitation valve 5 to automatically return to the initial position under the action of the internal spring or other reset mechanism. After the valve core of the anti-cavitation valve 5 is automatically reset, the first oil port 51 of the anti-cavitation valve is reconnected with the first oil circuit 81, the second oil port 52 of the anti-cavitation valve is reconnected with the second oil circuit 82, and the third oil port 53 of the anti-cavitation valve is reconnected with the third oil circuit 83. In this connected state, whether the first oil port 41 of the main control valve or the second oil port 42 of the main control valve is in a negative pressure state, hydraulic oil can be immediately drawn from the oil tank 1 for replenishment to prevent cavitation caused by negative pressure. For example, if a negative pressure state appears at the first oil port 41 of the main control valve, the hydraulic oil can be quickly poured into the first oil port 41 of the main control valve from the oil tank 1 via the third oil circuit 83, the third oil port 53 of the anti-cavitation valve, the first oil port 51 of the anti-cavitation valve and the first oil circuit 81; similarly, if a negative pressure state appears at the second oil port 42 of the main control valve, the hydraulic oil can also be quickly poured into the second oil port 42 of the main control valve from the oil tank 1 via the third oil circuit 83, the third oil port 53 of the anti-cavitation valve, the second oil port 52 of the anti-cavitation valve and the second oil circuit 82.

[0052] Furthermore, the hydraulic system also includes a main pump 6 and a cylinder 7, the main pump 6 having a main pump oil inlet 61 and a main pump oil outlet 62, the main pump oil inlet 61 is connected to the oil tank 1, the main pump oil outlet 62 is connected to the main control valve 4, and the cylinder 7 and the main pump 6 are connected through the main control valve 4 to control the flow direction of the oil out of the main pump oil outlet 62.

[0053] Specifically, the main pump 6 is the main power source of the entire hydraulic system, responsible for providing high-pressure hydraulic oil to drive the actuators (such as the cylinder 7, motor, etc.). The main pump 6 has a main pump oil inlet 61 and a main pump oil outlet 62. The main pump oil inlet 61 is connected to the oil tank 1 to ensure that hydraulic oil can be continuously extracted from the oil tank 1. The main pump oil outlet 62 is connected to the main control valve 4 to deliver the high-pressure hydraulic oil to the main control valve 4, and then distribute it to each actuator. The cylinder 7 is one of the actuators, which is used to realize the working actions of the excavator (such as excavation, loading, etc.). The cylinder 7 is connected to the main pump 6 through the main control valve 4, and the main control valve 4 controls the flow direction of the oil out of the main pump oil outlet 62, thereby controlling the movement direction and speed of the cylinder 7. The main control valve 4 adjusts the flow direction and flow rate of the hydraulic oil according to the operating instructions. When the pilot valve 3 is in the initial state, the first oil port and the second oil port of the main control valve 4 are respectively connected with the first oil port and the second oil port of the anti-cavitation valve 5, and the third oil port 53 of the anti-cavitation valve is connected with the oil tank 1, so as to ensure that the oil can be quickly replenished when needed. The main control valve 4 controls the movement of its internal valve core by receiving the pressure signal from the pilot valve 3, thereby changing the flow direction of the hydraulic oil and finally controlling the action of the oil cylinder 7.

[0054] The present invention also provides a method for preventing cavitation of an excavator hydraulic system, using the above-mentioned anti-cavitation hydraulic system for an excavator;

[0055] When the valve core of the main control valve 4 is close to the first oil port 41 of the main control valve and the first oil port 41 of the main control valve is in a negative pressure state during the resetting process of the main control valve 4, the automatic oil replenishing valve is switched to the first oil port of the oil replenishing valve to communicate with the third oil port of the oil replenishing valve, so that the negative pressure state of the first oil port 41 of the main control valve can draw hydraulic oil from the oil tank 1 and pour it into the main control valve 4 through the third oil port of the oil replenishing valve and the first oil port 41 of the main control valve in sequence;

[0056] When the valve core of the main control valve 4 is close to the second oil port 42 of the main control valve and the main control valve 4 is in a negative pressure state, the automatic oil replenishing valve is switched to the second oil port of the oil replenishing valve and is connected to the third oil port of the oil replenishing valve, so that the negative pressure state of the second oil port 42 of the main control valve can draw hydraulic oil from the oil tank 1 and pour it into the main control valve 4 through the third oil port of the oil replenishing valve and the second oil port 42 of the main control valve in sequence.

[0057] Specifically, when the valve core of the main control valve 4 is close to the first oil port 41 of the main control valve:

[0058] When the valve core of the main control valve 4 starts to reset from the position close to the first oil port 41 of the main control valve, if the first oil port 41 of the main control valve is in a negative pressure state, if it is a solenoid valve, the system will monitor the negative pressure state, and if it is an anti-cavitation valve 5, the first oil port 51, the second oil port 52 and the third oil port 53 of the anti-cavitation valve 5 are in a connected state, and the hydraulic oil can be quickly poured into the first oil port 41 of the main control valve from the oil tank 1 through the third oil circuit 83, the third oil port 53 of the anti-cavitation valve, the first oil port 51 of the anti-cavitation valve and the first oil circuit 81, ensuring that the hydraulic oil in the main control valve 4 is replenished in time. In this way, the negative pressure state of the first oil port 41 of the main control valve is quickly eliminated, avoiding the occurrence of cavitation, and ensuring the normal reset of the main control valve 4.

[0059] When the valve core of the main control valve 4 is close to the second oil port 42 of the main control valve:

[0060] When the valve core of the main control valve 4 starts to reset from the position close to the second oil port 42 of the main control valve, if the second oil port 42 of the main control valve is in a negative pressure state, if it is a solenoid valve, the system will monitor the negative pressure state, and if it is an anti-cavitation valve 5, the first oil port 51, the second oil port 52 and the third oil port 53 of the anti-cavitation valve 5 are in a connected state. The hydraulic oil can be quickly poured into the second oil port 42 of the main control valve from the oil tank 1 through the third oil circuit 83, the third oil port 53 of the anti-cavitation valve, the second oil port 52 of the anti-cavitation valve and the second oil circuit 82, ensuring that the hydraulic oil in the main control valve 4 is replenished in time. In this way, the negative pressure state of the second oil port 42 of the main control valve is quickly eliminated, avoiding the occurrence of cavitation, and ensuring the normal reset of the main control valve 4.

[0061] The present invention also provides an excavator, comprising the above-mentioned excavator anti-cavitation hydraulic system.

[0062] Specifically, in normal working state:

[0063] The main pump 6 extracts hydraulic oil from the oil tank 1 and delivers the high-pressure hydraulic oil to the main control valve 4 through the main pump oil outlet 62. The driver operates the pilot handle to make the pilot valve 3 output hydraulic oil to the fourth or fifth oil port of the anti-cavitation valve 5, pushing the valve core of the anti-cavitation valve 5 to move, thereby changing the flow direction of the hydraulic oil. The main control valve 4 adjusts the position of its internal valve core according to the signal of the pilot valve 3, controls the hydraulic oil to flow to the cylinder 7, and drives the cylinder 7 to perform corresponding actions.

[0064] During the resetting process of the main control valve 4, if a negative pressure state occurs in the first oil port 41 or the second oil port of the main control valve, the anti-cavitation valve 5 will quickly switch to the corresponding oil circuit to ensure that hydraulic oil can be quickly drawn from the oil tank 1 for replenishment to prevent cavitation.

[0065] For example, if a negative pressure state appears in the first oil port 41 of the main control valve, the first oil port 51 of the anti-cavitation valve is connected to the third oil port, and the hydraulic oil can be quickly poured into the first oil port 41 of the main control valve from the oil tank 1 via the third oil circuit 83, the third oil port 53 of the anti-cavitation valve, the first oil port 51 of the anti-cavitation valve and the first oil circuit 81; similarly, if a negative pressure state appears in the second oil port 42 of the main control valve, the hydraulic oil can also be quickly poured into the second oil port 42 of the main control valve from the oil tank 1 via the third oil circuit 83, the third oil port 53 of the anti-cavitation valve, the second oil port 52 of the anti-cavitation valve and the second oil circuit 82.

[0066] When the main control valve 4 receives the correct control signal, it will accurately control the flow direction of the oil out of the main pump oil outlet 62 to ensure that the hydraulic oil reaches the cylinder 7 along a predetermined path.

[0067] After the hydraulic oil enters the oil cylinder 7, it pushes the piston rod to move, realizing the operation of digging, loading, etc. After the operation is completed, the hydraulic oil in the oil cylinder 7 flows back to the oil tank 1 through the main control valve 4, forming a complete hydraulic cycle.

[0068] The technical means disclosed in the scheme of the present invention are not limited to the technical means disclosed in the above-mentioned implementation mode, but also include technical schemes composed of any combination of the above-mentioned technical features. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications are also regarded as the protection scope of the present invention.

Claims

1. An anti-cavitation hydraulic system for an excavator, characterized in that: include: Fuel tank (1); A pilot pump (2), the pilot pump (2) having a pilot pump oil inlet (21) and a pilot pump oil outlet (22), the pilot pump oil inlet (21) being in communication with the oil tank (1); A pilot valve (3), the pilot valve (3) comprising a first pilot valve oil outlet (31), a second pilot valve oil outlet (32), a pilot valve oil inlet (33) and a pilot valve oil return port (34), the pilot valve oil inlet (33) being in communication with the pilot pump oil outlet (22), and the pilot valve oil return port (34) being in communication with the oil tank (1); A main control valve (4), the main control valve (4) having a first oil port (41) and a second oil port (42) of the main control valve, the first oil port (41) and the second oil port (42) of the main control valve being respectively arranged at two ends of the valve core movement direction of the main control valve (4), so that after the first oil port (41) of the main control valve obtains oil, the valve core of the main control valve (4) is driven to slide toward the second oil port (42) of the main control valve, and after the second oil port (42) of the main control valve obtains oil, the valve core of the main control valve (4) is driven to slide toward the first oil port (41) of the main control valve, the first oil outlet (31) of the pilot valve is communicated with the first oil port (41) of the main control valve, and the second oil outlet (32) of the pilot valve is communicated with the second oil port (42) of the main control valve; An automatic oil replenishing valve, the automatic oil replenishing valve having a first oil replenishing valve port, a second oil replenishing valve port and a third oil replenishing valve port, the third oil replenishing valve port being in communication with the oil tank (1); When the first oil port (41) of the main control valve is in a negative pressure state, the automatic oil replenishing valve switches to the first oil port of the oil replenishing valve to communicate with the third oil port of the oil replenishing valve, so that the negative pressure state of the first oil port (41) of the main control valve can draw hydraulic oil from the oil tank (1) and pour it into the main control valve (4) in sequence through the third oil port of the oil replenishing valve and the first oil port (41) of the main control valve; When the second oil port (42) of the main control valve is in a negative pressure state, the automatic oil replenishing valve switches to connect the second oil port of the oil replenishing valve with the third oil port of the oil replenishing valve, so that the negative pressure state of the second oil port (42) of the main control valve can draw hydraulic oil from the oil tank (1) and inject it into the main control valve (4) through the third oil port of the oil replenishing valve and the second oil port (42) of the main control valve in sequence.

2. The anti-cavitation hydraulic system for excavators according to claim 1, characterized in that: The automatic oil replenishing valve is an anti-cavitation valve (5), and the anti-cavitation valve (5) has a first oil port (51) of the anti-cavitation valve, a second oil port (52) of the anti-cavitation valve, a third oil port (53) of the anti-cavitation valve, a fourth oil port (54) of the anti-cavitation valve, and a fifth oil port (55) of the anti-cavitation valve. The first oil port (51) of the anti-cavitation valve is the first oil port of the oil replenishing valve, the second oil port (52) of the anti-cavitation valve is the second oil port of the oil replenishing valve, the third oil port (53) of the anti-cavitation valve is the third oil port of the oil replenishing valve, and the first oil port (51) of the anti-cavitation valve and the second oil port (52) of the anti-cavitation valve are the second oil port of the oil replenishing valve. The second oil port (52) of the cavitation valve and the third oil port (53) of the anti-cavitation valve are in a communicating state, and the fourth oil port (54) of the anti-cavitation valve and the fifth oil port (55) of the anti-cavitation valve are respectively located at two ends of the movement direction of the valve core of the anti-cavitation valve (5), so that after the fourth oil port (54) of the anti-cavitation valve receives oil, the valve core of the anti-cavitation valve (5) is driven to slide toward the fifth oil port (55) of the anti-cavitation valve, and after the fifth oil port (55) of the anti-cavitation valve receives oil, the valve core of the anti-cavitation valve (5) is driven to slide toward the fourth oil port (54) of the anti-cavitation valve.

3. The anti-cavitation hydraulic system for excavators according to claim 2, characterized in that: The pilot valve (3) is controlled by a pilot handle, and the pilot valve (3) has an initial state, a first state and a second state; The initial state of the pilot valve (3) is that the first oil outlet (31) and the second oil outlet (32) of the pilot valve are both in a cut-off state, the first oil outlet (51) of the anti-cavitation valve is connected to the first oil outlet (41) of the main control valve via a first oil passage (81), the second oil outlet (52) of the anti-cavitation valve is connected to the second oil outlet (42) of the main control valve via a second oil passage (82), and the third oil outlet (53) of the anti-cavitation valve is connected to the oil tank (1) via a third oil passage (83); The first state of the pilot valve (3) is a state in which the pilot valve oil inlet (33) and the pilot valve first oil outlet (31) are in conduction, and the pilot valve first oil outlet (31) supplies oil to the anti-cavitation valve fourth oil port (54) to push the valve core of the anti-cavitation valve (5) to slide toward the anti-cavitation valve fifth oil port (55). After the valve core of the anti-cavitation valve (5) has completed sliding, the pilot valve (3) is connected to the main oil port (55) through the first oil passage (81). The first oil port (41) of the main control valve is connected to the first oil port (41) of the main control valve, and the oil obtained from the first oil port (41) of the main control valve pushes the valve core of the main control valve (4) to slide toward the second oil port (42) of the main control valve, thereby completing the sliding switching of the valve core of the main control valve (4) from the first oil port (41) of the main control valve to the second oil port (42) of the main control valve, and the return oil of the main control valve (4) flows from the second oil port (42) of the main control valve through the pilot valve (3) into the oil tank (1); The second state of the pilot valve (3) is a state in which the pilot valve oil inlet (33) and the pilot valve second oil outlet (32) are in conduction, and the pilot valve second oil outlet (32) supplies oil to the anti-cavitation valve fifth oil port (55) to push the valve core of the anti-cavitation valve (5) to slide toward the anti-cavitation valve fourth oil port (54). After the valve core of the anti-cavitation valve (5) has completed sliding, the pilot valve (3) is connected to the anti-cavitation valve (5) through the first oil passage (81). The second oil port (42) of the main control valve is connected, and the second oil port (42) of the main control valve pushes the valve core of the main control valve (4) to slide in the direction of the first oil port (41) of the main control valve, completing the sliding switching of the valve core of the main control valve (4) from the second oil port (42) of the main control valve to the first oil port (41) of the main control valve, and the return oil of the main control valve (4) flows from the first oil port (41) of the main control valve through the pilot valve (3) into the oil tank (1).

4. The anti-cavitation hydraulic system for excavators according to claim 3, characterized in that: When the pilot valve (3) is switched to the initial state, the anti-cavitation valve (5) is automatically reset to a state where the first oil port (51) of the anti-cavitation valve is connected to the first oil circuit (81), the second oil port (52) of the anti-cavitation valve is connected to the second oil circuit (82), and the third oil port (53) of the anti-cavitation valve is connected to the third oil circuit (83).

5. An anti-cavitation hydraulic system for an excavator according to any one of claims 1 to 4, characterized in that: The invention also comprises a main pump (6) and an oil cylinder (7), wherein the main pump (6) has a main pump oil inlet (61) and a main pump oil outlet (62), wherein the main pump oil inlet (61) is connected to the oil tank (1), and the main pump oil outlet (62) is connected to the main control valve (4), and the oil cylinder (7) and the main pump (6) are connected via the main control valve (4) so ​​as to control the flow direction of the oil out of the main pump oil outlet (62).

6. A method for preventing cavitation of an excavator hydraulic system, using the excavator anti-cavitation hydraulic system according to any one of claims 1 to 5, characterized in that: When the valve core of the main control valve (4) is close to the first oil port (41) of the main control valve and the first oil port (41) of the main control valve is in a negative pressure state during the resetting process of the main control valve (4), the automatic oil replenishing valve is switched to communicate with the first oil port of the oil replenishing valve and the third oil port of the oil replenishing valve, so that the negative pressure state of the first oil port (41) of the main control valve can draw hydraulic oil from the oil tank (1) and pour it into the main control valve (4) through the third oil port of the oil replenishing valve and the first oil port (41) of the main control valve in sequence; When the valve core of the main control valve (4) is close to the second oil port (42) of the main control valve and the second oil port (42) of the main control valve is in a negative pressure state during the resetting process of the main control valve (4), the automatic oil replenishing valve is switched to communicate with the second oil port of the oil replenishing valve and the third oil port of the oil replenishing valve, so that the negative pressure state of the second oil port (42) of the main control valve can draw hydraulic oil from the oil tank (1) and pour it into the main control valve (4) in sequence through the third oil port of the oil replenishing valve and the second oil port (42) of the main control valve.

7. An excavator, characterized in that: The invention comprises the anti-cavitation hydraulic system for an excavator as described in any one of claims 1 to 6.

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