Excavators and their hydraulic systems

Abstract

This invention relates to excavators, specifically an excavator and its hydraulic system. The hydraulic system includes a main control valve, a left pump and a right pump connected to the main control valve, a pusher control main valve mounted on the main control valve, a pusher pilot valve for controlling the pusher control main valve, an upper movement detection oil circuit, and a travel detection oil circuit. A first shuttle valve has two input terminals connected to the pilot output terminal of the pusher pilot valve. A second shuttle valve has two input terminals connected to the output terminal of the first shuttle valve and the pressure feedback terminal of the upper movement detection oil circuit, respectively. A spool valve's hydraulic control terminal is connected to the output terminal of the second shuttle valve, and its two controllable on / off ports are connected to the pressure feedback terminal of the travel detection oil circuit and the hydraulic control terminal of the dual-sided travel valve in the main control valve, respectively. This invention allows for the installation of shuttle valves and spool valves at a lower cost without modifying the original main control valve, and enables the control of the dual-sided travel valves to switch direction during pusher lifting or upper movement simultaneously with travel.

Description

Technical Field

[0001] This invention relates to an excavator, and more specifically, to an excavator and its hydraulic system. Background Technology

[0002] In the hydraulic system of a negative flow excavator, the main control valve 10, such as... Figure 1 As shown, it includes a left travel linkage control main valve 12, a right travel linkage control main valve 13, a boom linkage control main valve, a stick linkage control main valve, a bucket linkage control main valve 17, and a swing linkage control main valve 14. Among them, the boom linkage control main valve is equipped with a boom linkage main valve 15 and a boom combined flow valve 16, and the stick linkage control main valve is equipped with a stick linkage main valve 18 and a stick combined flow valve 19.

[0003] The hydraulic system typically employs a dual-pump oil supply configuration. The left pump supplies oil to the left travel linkage control main valve 12, boom linkage main valve 15, bucket linkage control main valve 17, and stick linkage flow valve 18. The right pump supplies oil to the right travel linkage control main valve 13, swing linkage control main valve 14, boom linkage flow valve 16, and stick linkage main valve 19. Normally, boom and stick movements are supplied by a combined flow from both pumps. Swing and right travel movements are supplied solely by the right pump. Left travel and bucket movements are supplied independently by the left pump. This oil supply mode is considered the conventional oil supply mode.

[0004] The above-described oil supply configuration is suitable for most working conditions of excavators, but there are exceptions. For example, when performing bilateral travel actions while simultaneously performing at least one overhead action, due to the lower load on the travel motors, when using the conventional oil supply mode, the pressure oil supplied by the left and right pumps preferentially flows to the left and right travel motors with lower loads, resulting in sluggish overhead actions. Overhead actions refer to the actions performed by the hydraulic actuators on the upper body of the excavator under the control of the corresponding control main valves, including boom action, stick action, bucket action, and swing action. Bilateral travel actions refer to the actions in which both the left and right travel motors rotate under the control of the corresponding travel control main valves. To address the issue of bilateral travel actions affecting overhead actions, a bilateral travel valve 11 is configured in the main control valve to switch the oil supply of each control main valve. When performing unilateral travel or no travel, oil is supplied according to the aforementioned conventional oil supply mode; when performing bilateral travel, the bilateral travel valve 11 is reversed, so that the right pump supplies oil to the two travel motors, and the left pump supplies oil to other hydraulic actuators other than the left and right travel motors, ensuring that the upper movement and travel oil supply do not interfere with each other. This oil supply mode is called the bilateral travel oil supply mode.

[0005] To achieve the aforementioned switching of the oil supply mode by the dual-sided travel valve, a dual-sided travel detection oil circuit 21 and an upper action detection oil circuit 22 are provided in the main control valve 10. The dual-sided travel detection oil circuit 21 flows through the left and right travel linkage control main valves. It is cut off when both left and right travel motors are moving simultaneously, and otherwise it is open. When the dual-sided travel detection oil circuit 21 is open, its pressure feedback end cannot build up pressure; when the dual-sided travel detection oil circuit 21 is closed, its pressure feedback end can build up pressure. The upper action detection oil circuit 22 flows sequentially through the control main valves of each upper action linkage in the main control valve. In each linkage control main valve corresponding to each upper action, when any linkage control main valve has a reversing action, that linkage control main valve reverses, causing the entire upper action detection oil circuit 22 to be cut off. When all linkage control main valves have no reversing action, the upper action detection oil circuit 22 is open. The control end of the double-sided travel valve 11 is connected to the pressure feedback end of the double-sided travel detection oil circuit 21 and the pressure feedback end of the upper motion detection oil circuit 22. When both the double-sided travel detection oil circuit 21 and the upper motion detection oil circuit 22 are cut off, the control end of the double-sided travel valve 11 establishes pressure, the double-sided travel valve 11 reverses, and the oil supply mode is switched from the normal oil supply mode to the double-sided travel oil supply mode.

[0006] Some excavators are equipped with bulldozer blades for operational purposes. Since the bulldozer blade is a non-essential attachment, the main control valve typically does not include a separate main control valve for controlling the blade. After the bulldozer blade is added, a bulldozer blade valve 20 is usually installed on the main control valve to control its raising and lowering. The valve is supplied with oil by the left pump. However, because the valve 20 is an aftermarket addition, the original upper motion detection oil circuit 22 on the main control valve 10 cannot flow through it, and therefore cannot detect whether the bulldozer blade is raising or lowering. Consequently, after the bulldozer blade is added, a slow raising and lowering action occurs when both sides are traveling simultaneously. Connecting the bulldozer blade valve to the upper motion detection oil circuit would require modifying the main control valve's oil circuitry, significantly increasing costs. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide an excavator and its hydraulic system, which, after adding a bulldozer blade, adds a bulldozer blade valve plate and does not modify the upper action detection oil circuit of the original main control valve, so as to realize a dual-side travel oil supply mode when both the bulldozer blade and the left and right travel are in motion.

[0008] The technical solution of the present invention to achieve its purpose is: an excavator hydraulic system, including a main control valve, a left pump and a right pump connected to the main control valve, a pusher control main valve installed on the main control valve, and a pusher pilot valve for controlling the pusher control main valve;

[0009] The hydraulic system also includes:

[0010] The upper action detection oil circuit is used to detect the upper actions controlled by the main control valve in the main control valve. When any control main valve that controls the upper action switches, pressure is established at its pressure feedback end.

[0011] The travel detection oil circuit is used to detect travel motion. When either the left or right travel linkage in the main control valve switches direction, pressure is established at its pressure feedback end.

[0012] The first shuttle valve has two input ends connected to the pilot output end of the pusher pilot valve;

[0013] The second shuttle valve has two input terminals connected to the output terminal of the first shuttle valve and the pressure feedback terminal of the upper motion detection oil circuit, respectively.

[0014] The slide valve has a hydraulic control end connected to the output end of the second shuttle valve. Its two controllable opening and closing ports are connected to the pressure feedback end of the travel detection oil circuit and the hydraulic control end of the double-sided travel valve in the main control valve.

[0015] In the hydraulic system of the excavator of this invention, the main control valve contains:

[0016] The boom control main valve, bucket control main valve, stick control main valve, stick confluence valve, and pusher control main valve in the boom control main valve are connected to the left pump for oil supply.

[0017] The right-side travel linkage control main valve is connected to the right pump oil supply;

[0018] The first and second oil inlets of the double-sided travel valve are connected to the left and right pumps respectively for oil supply; the first oil outlet is connected to the left travel linkage control main valve for oil supply, and the second oil outlet is connected to the swing linkage control main valve, the boom confluence valve in the boom linkage control main valve, and the stick linkage control main valve in the stick linkage control main valve for oil supply; under normal conditions, the first and second oil inlets of the double-sided travel valve are connected to the first and second oil outlets respectively, and under hydraulic control, the first and second oil inlets are connected to the second and first oil outlets respectively.

[0019] In the hydraulic system of the excavator of the present invention, the slide valve is a two-position three-way valve. The two oil ports connected to the pressure feedback end of the travel detection oil circuit and the hydraulic control end of the double-sided travel valve in the main control valve are the oil inlet and the oil outlet, respectively. The oil return port is connected to the hydraulic oil tank, and the oil outlet can be selectively connected to either the oil inlet or the oil return port.

[0020] In the excavator hydraulic system of this invention, the upper movement detection oil circuit is composed of a series of switching valves in the main control valve that controls each upper movement, or a series of switching valves in the main control valve that are linked to the main control valve that controls each upper movement. Each switching valve in the upper movement detection oil circuit is open when the corresponding main control valve is in the neutral position and closed when the corresponding main control valve is in the reversing position. The pressure feedback end of the upper movement detection oil circuit is connected to the pilot oil source via a damping valve, and the other end is connected to the hydraulic oil tank. The pressure feedback end of the bilateral travel detection oil circuit is unidirectionally connected to the pressure feedback end of the upper movement detection oil circuit via a check valve.

[0021] In the hydraulic system of the excavator of this invention, the bilateral travel detection oil circuit consists of a left-travel detection oil circuit and a right-travel detection oil circuit connected in parallel. The left-travel detection oil circuit is composed of a switching valve in the left-travel linkage control main valve of the main control valve, or a switching valve linked with the left-travel linkage control main valve. The right-travel detection oil circuit is composed of a switching valve in the right-travel linkage control main valve of the main control valve, or a switching valve linked with the right-travel linkage control main valve. Each switching valve of the bilateral travel detection oil circuit is open when the corresponding travel linkage control main valve is in the neutral position and closed when the corresponding travel linkage control main valve is in the reversing position. The pressure feedback end of the bilateral travel detection oil circuit is connected to the pilot oil source via a damping valve, and the other end is connected to the hydraulic oil tank.

[0022] In the hydraulic system of the excavator of the present invention, the travel detection oil circuit is composed of a series of switching valves in the left and right travel linkage control main valve of the main control valve, or a series of switching valves in the main control valve that are linked to the left and right travel linkage control main valve. Each switch of the travel detection oil circuit is turned on when the corresponding travel linkage control main valve is in the neutral position and turned off when the corresponding travel linkage control main valve is in the reversing position. The pressure feedback end of the travel detection oil circuit is connected to the pilot oil source through a damping valve, and the other end is connected to the hydraulic oil tank.

[0023] In the hydraulic system of the excavator of the present invention, the travel detection oil circuit can also be composed of a shuttle valve group consisting of three shuttle valves with four input ends and one output end. The four input ends of the shuttle valve group are connected to the four pilot output ends of the left and right travel pilot valves that control the left and right travel linkage main valves. The output end of the shuttle valve group is a pressure feedback end.

[0024] The technical solution of the present invention to achieve its purpose is: an excavator having the aforementioned excavator hydraulic system.

[0025] Compared with the prior art, the present invention can control the switching of the bilateral travel valve by setting shuttle valve and slide valve without modifying the original main control valve, when the pusher is raised or lowered or the upper part is moved, while the bilateral travel is being carried out. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the main control valve in an existing excavator hydraulic system.

[0027] Figure 2 This is a schematic diagram of the hydraulic system of the excavator according to the present invention.

[0028] Figure 3 yes Figure 2 A partial enlarged view of the control section of the double-sided travel valve.

[0029] Component names and serial numbers in the diagram:

[0030] Main control valve 10, double travel valve 11, left travel linkage control main valve 12, right travel linkage control main valve 13, swing linkage control main valve 14, boom linkage main valve 15, boom confluence valve 16, bucket linkage control main valve 17, stick confluence valve 18, stick linkage main valve 19, pusher control main valve 20, double travel detection oil circuit 21, left travel detection oil circuit 211, right travel detection oil circuit 212, upper movement detection oil circuit 22, travel detection oil circuit 23, first damping valve 24, second damping valve 25, third damping valve 26, check valve 27.

[0031] Left travel motor 31, right travel motor 32, swing motor 33, boom cylinder 34, bucket cylinder 36, stick cylinder 37, pusher cylinder 38, left pump 39, right pump 40, pilot oil source 41, pusher pilot valve 42, first shuttle valve 43, second shuttle valve 44, slide valve 45. Detailed Implementation

[0032] The specific implementation plan is described below with reference to the attached diagram.

[0033] like Figure 2 Figure 3 As shown, the excavator hydraulic system includes a main control valve 10, a left pump 39 and a right pump 40 connected to the main control valve 10, a pusher control main valve 20 installed on the main control valve 10, and a pusher pilot valve 42 for controlling the pusher control main valve 20; the pressure feedback end of the bilateral travel detection oil circuit 21 in the main control valve 10 is connected to the pressure feedback end of the upper action detection oil circuit 22 via a check valve 27.

[0034] The hydraulic system also includes a travel detection oil circuit 23, a first shuttle valve 43, a second shuttle valve 44, a slide valve 45, etc.

[0035] The travel detection oil circuit 23 is used to detect whether there is a travel action. When either the left travel control main valve 12 or the right travel control main valve 13 in the main control valve 10 reverses, pressure is established at the pressure feedback end of the travel detection oil circuit 23.

[0036] The two input ends of the first shuttle valve 43 are connected to the pilot output end of the pusher pilot valve 42. When the pusher pilot valve 42 is operated to realize the lifting and lowering action of the bulldozer blade, the output end of the first shuttle valve 43 can output pilot pressure oil.

[0037] The two input terminals of the second shuttle valve 44 are connected to the output terminal of the first shuttle valve 43 and the pressure feedback terminal of the upper action detection oil circuit 22, respectively. When the excavator performs upper actions or bulldozer blade lifting actions, the output terminal of the second shuttle valve can output pilot pressure oil.

[0038] The hydraulic control end of the slide valve 45 is connected to the output end of the second shuttle valve 44. Its two controllable on / off ports are connected to the pressure feedback end of the travel detection oil circuit and the hydraulic control end of the double-sided travel valve in the main control valve. When the excavator performs an overhead movement or a bulldozer blade lifting / lowering movement, the slide valve 45 reverses, and the pressure feedback end of the travel detection oil circuit 23 connects to the hydraulic control end of the double-sided travel valve 11.

[0039] In this embodiment, when there is a single-sided or double-sided travel action, the corresponding valves in the left travel linkage control main valve 12 and the right travel linkage control main valve 13 of the main control valve 10 switch, so that pressure is established at the pressure feedback end of the travel detection oil circuit 23. At this time, if the bulldozer blade is raised or lowered, the pilot output end of the bulldozer blade pilot valve 42 outputs pilot pressure oil to control the bulldozer blade control main valve 20. The pilot pressure oil output by the bulldozer blade pilot valve 42 is led out through the first shuttle valve 43 and then acts on the hydraulic control end of the slide valve 45 through the second shuttle valve 44. The slide valve 45 switches, and the oil circuit between the pressure feedback end of the travel detection oil circuit 23 and the hydraulic control end of the double-sided travel valve 11 is connected, so that the double-sided travel valve 11 switches and switches the oil supply mode. The oil supply mode of the main control valve 10 to each hydraulic actuator is changed from the conventional oil supply mode to the double-sided travel oil supply mode.

[0040] like Figure 2 As shown, the main control valve 10 of the excavator's hydraulic system includes: a left travel linkage control main valve 12 for controlling the left travel motor 31, a right travel linkage control main valve 13 for controlling the right travel motor 32, a swing linkage control main valve 14 for controlling the swing motor 33, a boom linkage control main valve for controlling the extension and retraction of the boom cylinder 34, a stick linkage control main valve for controlling the extension and retraction of the stick cylinder 37, and a bucket linkage control main valve 17 for controlling the extension and retraction of the bucket cylinder 36. The boom linkage control main valve includes a boom linkage main valve 15 and a boom confluence valve 16; the stick linkage control main valve includes a stick confluence valve 18 and a stick linkage main valve 19. The boom linkage main valve 15 and the boom confluence valve 16 combine to output flow, and the stick confluence valve 18 and the stick linkage main valve 19 combine to output flow, thereby outputting a large flow rate during boom and stick movements, enabling rapid extension and retraction of the boom cylinder 34 and the stick cylinder 37.

[0041] The main control valve 20 for controlling the bulldozer cylinder 38 to achieve the raising and lowering of the bulldozer blade is installed on the main control valve 10. The main control valve 20 is connected to the bulldozer pilot valve 42 and is controlled by the bulldozer pilot valve 42 to switch directions.

[0042] Left pump 39 is connected to the P1 pump source port of main control valve 10, and right pump 40 is connected to the P2 pump source port of main control valve 10. The boom linkage main valve 15, bucket linkage control main valve 17, stick confluence valve 18, and pusher control main valve 20 are connected to left pump 39 for oil supply. That is, during boom, bucket, stick, and pusher blade movements, left pump 39 supplies working pressure oil to the corresponding hydraulic actuators through the corresponding control main valves or main valves. The oil supply connection is achieved through pipeline connections for conveying the working pressure oil.

[0043] The right travel linkage control main valve 13 is connected to the right pump 40 for oil supply. When performing right travel, the right pump 40 supplies working pressure oil to drive the right travel motor 32 through the right travel linkage control main valve 13.

[0044] The first oil inlet (C port) and the second oil inlet (D port) of the double-sided travel valve 11 are connected to the left pump 39 and the right pump 40 through the pump source port P1 and the pump source port P2 respectively; the first oil outlet (A port) is connected to the left travel linkage control main valve 12, and the second oil outlet (B port) is connected to the slewing linkage control main valve 14, the boom confluence valve 16, and the stick linkage main valve 19. When the double-sided travel valve 11 is in normal operation, i.e., when there is no pressure oil at its hydraulic control end and it is switching, the first oil inlet (C port) and the second oil inlet (D port) are connected to the first oil outlet (A port) and the second oil outlet (B port) respectively. At this time, the hydraulic system is in the normal oil supply mode. The high-pressure working oil supplied by the left pump 39 is supplied to the boom linkage main valve 15, the bucket linkage control main valve 17, the stick confluence valve 18, and the pusher control main valve 20, and is also supplied to the left travel linkage control main valve 12 through the first oil inlet (C port) and the first oil outlet (A port) of the double-sided travel valve 11. The right pump 40 supplies high-pressure working oil to the right travel linkage control main valve 13, and also supplies high-pressure working oil to the swing linkage control main valve 14, the boom confluence valve 16, and the stick linkage main valve 19 through the second oil inlet (D port) and the second oil outlet (B port) of the double-sided travel valve 11.

[0045] When the pressure control of the double-sided travel valve 11 is reversed at its hydraulic end, the first inlet (C port) and the second outlet (B port) are connected, and the second inlet (D port) and the first outlet (A port) are connected. At this time, the high-pressure working oil supplied by the right pump 40 is supplied to the right travel linkage control main valve 13, and also to the left travel linkage control main valve 12 through the second inlet (D port) and the first outlet (A port) of the double-sided travel valve 11. The high-pressure working oil supplied by the left pump 39 is supplied to the boom linkage main valve 15, the bucket linkage control main valve 17, the stick confluence valve 18, and the pusher control main valve 20, and also to the swing linkage control main valve 14, the boom confluence valve 16, and the stick linkage main valve 19 through the first inlet (C port) and the second outlet (B port) of the double-sided travel valve 11, so that the hydraulic system operates in the double-sided travel oil supply mode. In the dual-side travel oil supply mode, the left and right travel motors are supplied with oil separately by the right pump 40, while the upper action hydraulic actuators and the bulldozer blade cylinder 38 are supplied with oil by the left pump 39, thus achieving that the oil supply of the travel motors and the upper action hydraulic actuators does not interfere with each other.

[0046] like Figure 3 As shown, the slide valve 45 is a two-position three-way valve. The two oil ports connected to the pressure feedback end of the travel detection oil circuit 23 and the hydraulic control end of the double-sided travel valve 11 in the main control valve 10 are the oil inlet (E port) and the oil outlet (F port), respectively. The oil return port (G port) is connected to the hydraulic oil tank. The oil outlet (F port) can be connected to either the oil inlet (E port) or the oil return port (G port).

[0047] The upper motion detection oil circuit 22 is composed of a series of switching valves in the main control valve 10, each controlling the upper motion linkage main valve, which is open in the neutral position and closed in the reversing position. The pressure feedback end of the upper motion detection oil circuit 22 is connected to the pilot oil source 41 via the third damping valve 26, and the other end (Dr end) is connected to the hydraulic oil tank. In the upper motion detection oil circuit 22, the switching valve of each linkage main valve is open when the corresponding main control valve is in the neutral position, and closed when the main control valve reverses to perform the corresponding upper motion. One end (Dr end) of the upper motion detection oil circuit 22 is connected to the hydraulic oil tank, and the pressure feedback end is connected to the pilot oil source 41 via the third damping valve 26. When any upper motion is performed, the upper motion detection oil circuit 22 is closed due to the reversal of the main control valve, and pressure is established at the pressure feedback end of the upper motion detection oil circuit 22.

[0048] like Figure 2 Figure 3As shown, the dual-sided travel detection oil circuit 21 consists of a left-side detection oil circuit 211 and a right-side detection oil circuit 212 connected in parallel. The left-side detection oil circuit 211 is formed by a switching valve in the left-side travel control main valve 12. This switching valve is open when the left-side travel control main valve 12 is in the neutral position, and closed when the left-side travel control main valve 12 is in the reversing position (left or right). The right-side detection oil circuit 212 is formed by a switching valve in the right-side travel control main valve 12. This switching valve is open when the right-side travel control main valve 13 is in the neutral position, and closed when the right-side travel control main valve 13 is in the reversing position (left or right). The left-side and right-side detection oil circuits are connected in parallel, with one end (Dr end) connected to the hydraulic oil tank, and the other end connected to the pilot oil source 41 through the first damping valve 24. The dual-sided travel detection oil circuit 21 only closes when both the left-side detection oil circuit 211 and the right-side detection oil circuit 212 are in the closed state. That is, both the left-side travel linkage control main valve 12 and the right-side travel linkage control main valve 13 need to be in the reversing position to close. If there is only unilateral travel or no travel action, the left-side travel linkage control main valve 12 and the right-side travel linkage control main valve 13 are in the neutral position, or only one is in the neutral position. The dual-sided travel detection oil circuit 21 is in a conducting state, and pressure cannot be established at its pressure feedback end. The pressure feedback end of the dual-sided travel detection oil circuit 21 is connected to the pressure feedback end of the upper action detection oil circuit 22 through a check valve 27.

[0049] In this embodiment, the travel detection oil circuit 23 in the main control valve 10 is composed of the switching valves of the left travel linkage control main valve 12 and the right travel linkage control main valve 13 connected in series. The pressure feedback end of the travel detection oil circuit 23 is connected to the pilot oil source 41 via the second damping valve 25, and the other end (Dr end) is connected to the hydraulic oil tank. The switching valves are open when the corresponding travel linkage control main valve is in the neutral position and closed when in the reversing position. The travel detection oil circuit 23 is used to detect whether the excavator has a travel action, which includes single-sided travel and double-sided travel. When the excavator has a travel action (performing single-sided or double-sided travel), the switching valves on the travel detection oil circuit 23 are closed, and the pressure feedback end of the travel detection oil circuit 23 is not connected to the hydraulic oil tank but can still build pressure. When the excavator does not have a travel action, the pressure feedback end of the travel detection oil circuit 23 is connected to the hydraulic oil tank but cannot build pressure.

[0050] In this embodiment, if only single-sided or double-sided travel is performed, the pressure feedback terminal of the upper motion detection oil circuit 22 is connected to the hydraulic oil tank but cannot establish pressure. Since the pusher pilot valve 42 is not operated, there is no pilot pressure oil output. Therefore, there is no pressure oil input at the two input terminals of the second shuttle valve 44. The oil outlet (F port) and return port (G port) of the slide valve 45 are connected. The double-sided travel valve 11 is in the left position, and the excavator hydraulic system operates in the normal oil supply mode. The high-pressure working oil supplied by the left pump 39 is supplied to the left travel linkage control main valve 12, and the high-pressure working oil supplied by the right pump 40 is supplied to the right travel linkage control main valve 13.

[0051] When the excavator only performs the upper movement and / or the bulldozer blade lifting movement, the output pressure of the second shuttle valve 44 acts on the hydraulic control end of the slide valve 45, and the slide valve 45 switches. However, since there is no travel movement, the pressure feedback end of the travel detection oil circuit 23 is connected to the hydraulic oil tank and cannot establish pressure. That is, the oil inlet (E port) of the slide valve 45 does not have the pilot pressure to switch the double travel valve 11, and the excavator hydraulic system works in the normal oil supply mode.

[0052] When the excavator is both traveling and lifting, or when the bulldozer blade is raising or lowering, the pressure feedback terminal of the traveling detection oil circuit 23 builds up pressure due to the excavator's traveling motion, and this pressure acts on the oil inlet (Port E) of the slide valve. If the bulldozer blade is raising or lowering, the pilot pressure oil output by the first shuttle valve 43 acts on the hydraulic control terminal of the slide valve 45 via the second shuttle valve 44, causing it to switch direction. If the excavator is lifting, the pressure feedback terminal of the lifting motion detection oil circuit 22 can build up pressure and act on the hydraulic control terminal of the slide valve 45 via the second shuttle valve 44, causing it to switch direction. After the spool valve 45 reverses, the oil inlet (E port) and oil outlet (F port) are connected, causing the double-sided travel valve 11 to reverse. The excavator's hydraulic system switches from the conventional oil supply mode to the double-sided travel oil supply mode. At this time, the high-pressure oil for the left travel linkage control main valve 12 and the right travel linkage control main valve 13 is supplied by the right pump 40, while the high-pressure oil for the hydraulic actuators such as the bulldozer blade, boom, stick, bucket, and swing motor is supplied by the left pump 39. This ensures that the oil for travel and the oil for other hydraulic actuators are supplied by different hydraulic pumps, avoiding mutual interference.

[0053] In the above embodiment, the travel detection oil circuit 23 is composed of a series of switching valves that are linked to the main valve of the left and right travel linkage. In other embodiments, the travel detection oil circuit 23 can also have other forms. For example, the travel detection oil circuit 23 can also be composed of a shuttle valve group consisting of three shuttle valves. The three shuttle valves are connected to form a shuttle valve group with four input ends and one output end. The four input ends of the shuttle valve group are connected to the two pilot output ends of the left travel pilot valve and the two pilot output ends of the right travel pilot valve. The output end of the shuttle valve group is a pressure feedback end connected to one input end of the second shuttle valve. When single-sided or double-sided travel is performed, the pilot pressure oil output by the left travel pilot valve and / or the right travel pilot valve is output through the output end of the shuttle valve group and acts on the input end of the second shuttle valve to detect whether the excavator has a travel action.

[0054] This embodiment also provides an excavator having the aforementioned excavator hydraulic system.

[0055] In this embodiment, if a bulldozer blade is subsequently added to the excavator, only a bulldozer blade control main valve plate needs to be added to the original main control valve, along with two shuttle valves and one slide valve. The oil inlet of the bulldozer blade control main valve plate can be connected to the main oil circuit in the original main control valve that is connected to the oil supply to the left pump. There is no need to connect the upper motion detection oil circuit to the bulldozer blade control main valve plate, which facilitates modification and saves on modification costs.

Claims

1. A hydraulic system for an excavator, comprising a main control valve, a left pump and a right pump connected to the main control valve, a pusher control main valve mounted on the main control valve, and a pusher pilot valve for controlling the pusher control main valve; Its features are, The hydraulic system also includes: The upper action detection oil circuit is used to detect the upper actions controlled by the main control valve in the main control valve. When any control main valve that controls the upper action switches, pressure is established at its pressure feedback end. The travel detection oil circuit is used to detect travel motion. When either the left or right travel linkage in the main control valve switches direction, pressure is established at its pressure feedback end. The first shuttle valve has two input ends connected to the pilot output end of the pusher pilot valve; The second shuttle valve has two input terminals connected to the output terminal of the first shuttle valve and the pressure feedback terminal of the upper motion detection oil circuit, respectively. The slide valve has a hydraulic control end connected to the output end of the second shuttle valve. Its two controllable opening and closing ports are connected to the pressure feedback end of the travel detection oil circuit and the hydraulic control end of the double-sided travel valve in the main control valve.

2. The excavator hydraulic system according to claim 1, characterized in that, In the main control valve: The boom control main valve, bucket control main valve, stick control main valve, stick confluence valve, and pusher control main valve in the boom control main valve are connected to the left pump for oil supply. The right-side travel linkage control main valve is connected to the right pump oil supply; The first and second oil inlets of the double-sided travel valve are connected to the left and right pumps respectively for oil supply; the first oil outlet is connected to the left travel linkage control main valve for oil supply, and the second oil outlet is connected to the swing linkage control main valve, the boom confluence valve in the boom linkage control main valve, and the stick linkage control main valve in the stick linkage control main valve for oil supply; under normal conditions, the first and second oil inlets of the double-sided travel valve are connected to the first and second oil outlets respectively, and under hydraulic control, the first and second oil inlets are connected to the second and first oil outlets respectively.

3. The excavator hydraulic system according to claim 1, characterized in that, The slide valve is a two-position three-way valve. The two oil ports connected to the pressure feedback end of the travel detection oil circuit and the hydraulic control end of the double-sided travel valve in the main control valve are the oil inlet and the oil outlet, respectively. The oil return port is connected to the hydraulic oil tank, and the oil outlet can be connected to either the oil inlet or the oil return port.

4. The excavator hydraulic system according to claim 1, characterized in that, The upper motion detection oil circuit is composed of a series of switching valves in the main control valve that controls each upper motion, or a series of switching valves in the main control valve that are linked to the main control valve that controls each upper motion. Each switching valve in the upper motion detection oil circuit is open when the corresponding main control valve is in the neutral position and closed when the corresponding main control valve is in the reversing position. The pressure feedback end of the upper motion detection oil circuit is connected to the pilot oil source via a damping valve, and the other end is connected to the hydraulic oil tank.

5. The excavator hydraulic system according to claim 4, characterized in that, The pressure feedback end of the bilateral travel detection oil circuit is connected in one direction to the pressure feedback end of the upward movement detection oil circuit via a one-way valve.

6. The excavator hydraulic system according to claim 5, characterized in that, The bilateral travel detection oil circuit consists of a left-movement detection oil circuit and a right-movement detection oil circuit connected in parallel. The left-movement detection oil circuit is composed of a switching valve in the left-movement control main valve of the main control valve, or a switching valve linked with the left-movement control main valve. The right-movement detection oil circuit is composed of a switching valve in the right-movement control main valve of the main control valve, or a switching valve linked with the right-movement control main valve. Each switching valve of the bilateral travel detection oil circuit is open when the corresponding travel control main valve is in the neutral position and closed when the corresponding travel control main valve is in the reversing position. The pressure feedback end of the bilateral travel detection oil circuit is connected to the pilot oil source via a damping valve, and the other end is connected to the hydraulic oil tank.

7. The excavator hydraulic system according to claim 1, characterized in that, The travel detection oil circuit is composed of the series connection of the switching valves in the left and right travel linkage control main valve of the main control valve, or it is composed of the series connection of the switching valves in the main control valve that are linked to the left and right travel linkage control main valves. Each switch in the travel detection oil circuit is turned on when the corresponding travel linkage control main valve is in the neutral position and turned off when the corresponding travel linkage control main valve is in the reversing position. The pressure feedback end of the travel detection oil circuit is connected to the pilot oil source through a damping valve, and the other end is connected to the hydraulic oil tank.

8. The excavator hydraulic system according to claim 1, characterized in that, The travel detection oil circuit consists of three shuttle valves and a shuttle valve group with four input terminals and one output terminal. The four input terminals of the shuttle valve group are connected to the four pilot output terminals of the left and right travel pilot valves that control the left and right travel linkage main valves. The output terminal of the shuttle valve group is the pressure feedback terminal.

9. An excavator, characterized in that, An excavator hydraulic system having any one of claims 1 to 8.

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