Hydraulic circuit for construction machine

Abstract

An embodiment of the present invention relates to a hydraulic circuit of a construction machine, wherein the hydraulic circuit of the construction machine comprises a main pump unit that forms hydraulic fluid, a first control valve that receives hydraulic fluid from the main pump unit and controls one of the plurality of working machines, a second control valve that receives hydraulic fluid from the main pump unit and controls another of the plurality of working machines, a first hydraulic fluid supply line that guides the movement of hydraulic fluid from the main pump unit to the first control valve, the second control valve, and a tank, a bypass valve disposed on the first hydraulic fluid supply line and capable of selectively opening and closing the hydraulic fluid moving to the tank, a pilot pump that provides pilot hydraulic fluid, a control valve pilot line that guides the movement of hydraulic fluid from the pilot pump to the tank, a first pilot valve disposed on the control valve pilot line and connected to the first control valve, a second pilot valve disposed on the control valve pilot line and connected to the second control valve, and a bypass pilot line capable of branching and transmitting pilot pressure for the operation of the bypass valve.

Description

Technology Field

[0001] An embodiment of the present invention relates to a hydraulic circuit of a construction machine, and more specifically, to a hydraulic circuit of a construction machine that selectively discharges hydraulic fluid from a pump for operating a workpiece into a tank with reduced time difference depending on the use and cessation of the workpiece of the construction machine. Background Technology

[0002] Generally, construction machinery is driven by using hydraulic fluid to supply energy to the working implements connected to the boom, arm, attachment, upper body, and lower body.

[0003] The selection of these implements is made by the operator and is operated by receiving their signals.

[0004] Considering factors such as high pressure being formed in the valve for operating the workpiece or the temperature information of the operating fluid, the hydraulic fluid supplied to the valve for operating the workpiece is selectively diverted to the tank.

[0005] However, in such cases, it is necessary to selectively control by detecting sensors or signals for detecting various condition information. Furthermore, when controlling multiple valves, a time lag occurs during the process of receiving and transmitting each control signal, leading to problems such as the time required for hydraulic fluid to be discharged into the tank or the loss of flow rate due to the discharge of hydraulic fluid into the tank.

[0006] In other words, since separate devices, detection elements, and software for determining them must be provided to control multiple valves, there are problems such as increased costs and complex hydraulic circuits. The problem to be solved

[0007] An embodiment of the present invention relates to a hydraulic circuit of a construction machine in which a bypass valve is operated to reduce the time difference between the use and stoppage of the workpiece and to organically discharge the pressurized oil of a pump for the operation of the workpiece into a tank. means of solving the problem

[0008] According to an embodiment of the present invention, a hydraulic circuit of a construction machine that operates a plurality of workpieces of the construction machine comprises: a main pump unit that forms hydraulic fluid of an operating fluid; a first control valve that receives hydraulic fluid from the main pump unit and controls one of the plurality of workpieces; a second control valve that receives hydraulic fluid from the main pump unit and controls another of the plurality of workpieces; a first operating fluid supply line that guides the movement of hydraulic fluid from the main pump unit to the first control valve, the second control valve, and a tank; a bypass valve disposed on the first operating fluid supply line and capable of selectively opening and closing the hydraulic fluid moving to the tank; a pilot pump that provides pilot hydraulic fluid; a control valve pilot line that guides the movement of hydraulic fluid from the pilot pump to the tank; a first pilot valve disposed on the control valve pilot line and connected to the first control valve; a second pilot valve disposed on the control valve pilot line and connected to the second control valve; and a bypass pilot line capable of branching and transmitting pilot pressure for the operation of the bypass valve.

[0009] In addition, the hydraulic circuit of the construction machine described above further includes an engine that provides operating power for the main pump unit, and the engine can open the bypass valve and the first hydraulic fluid supply line at the beginning of startup.

[0010] In addition, when the first control valve and the second control valve are in a neutral state, the bypass valve can open the first operating fluid supply line to prevent the first control valve and the second control valve from malfunctioning.

[0011] In addition, when the first control valve and the second control valve are in a neutral state, the bypass valve opens the first hydraulic fluid supply line so that the hydraulic fluid supplied from the main pump moves to the tank and can raise the temperature of the hydraulic fluid.

[0012] Alternatively, if either the first pilot valve or the second pilot valve is not in a neutral state, the pilot pressure provided by the pilot pump can be transmitted to the bypass pilot line to operate the bypass valve.

[0013] In addition, when the working device connected to the first control valve is operated, the bypass valve is operated to prevent the pressurized oil passing through the first operating oil supply line from moving to the tank.

[0014] In addition, when the first pilot valve and the second pilot valve are in a neutral state, the bypass valve may not operate.

[0015] In addition, the first control valve is a swing control valve, and the working device connected to the first control valve is a swing motor. When the swing motor is in operation, the bypass valve is operated, and when the operation of the swing motor is stopped, the bypass valve can be switched so that it is not operated.

[0016] In addition, when the bypass valve is operated, the hydraulic fluid passing through the first hydraulic fluid supply line is prevented from moving to the tank, and when the bypass valve is not operated, the hydraulic fluid passing through the first hydraulic fluid supply line can move to the tank.

[0017] Alternatively, a hydraulic circuit of a construction machine that operates a plurality of implements according to an embodiment of the present invention comprises a first main pump that forms hydraulic fluid, a second main pump that forms hydraulic fluid, a first control valve that receives hydraulic fluid from the first main pump and controls one of the plurality of implements, a second control valve that receives hydraulic fluid from the first main pump and controls another of the plurality of implements, a third control valve that receives hydraulic fluid from the second main pump and controls yet another of the plurality of implements, a first hydraulic fluid supply line that guides the movement of hydraulic fluid from the first main pump to the first control valve and the second control valve, a second hydraulic fluid supply line that guides the movement of hydraulic fluid from the second main pump to the third control valve, a first bypass valve disposed on the first hydraulic fluid supply line and capable of selectively opening and closing the flow of hydraulic fluid received from the first hydraulic fluid supply line to a tank, and a first bypass valve disposed on the second hydraulic fluid supply line and from the first hydraulic fluid supply line A second bypass valve capable of selectively opening and closing the flow of received hydraulic fluid to a tank; a pilot pump that forms and provides pilot pressure with hydraulic fluid; a first pilot valve connected to the first control valve, receiving pilot pressure, and allowing the hydraulic fluid provided by the pilot pump to move to the tank when neutral; a second pilot valve connected to the second control valve, receiving pilot pressure, and allowing the hydraulic fluid provided by the pilot pump to move to the tank when neutral; a third pilot valve connected to the third control valve, receiving pilot pressure, and allowing the hydraulic fluid provided by the pilot pump to move to the tank when neutral; and a control valve pilot line that guides the movement of the hydraulic fluid provided by the pilot pump from the pilot pump to the first pilot valve, the second pilot valve, and the third pilot valve.It includes a first bypass pilot line capable of branching and delivering the operating fluid provided by the pilot pump for the operation of the first bypass valve, and a second bypass pilot line capable of branching and delivering the operating fluid provided by the pilot pump for the operation of the second bypass valve.

[0018] In addition, if any one of the first pilot valve, the second pilot valve, and the third pilot valve is not in a neutral position, the first bypass valve may be operated to close the first hydraulic fluid supply line, and the second bypass valve may be operated to close the second hydraulic fluid supply line.

[0019] In addition, when the first pilot valve, the second pilot valve, and the third pilot valve are all in the neutral position, the pressure of the operating fluid passing through the control valve pilot line and the pressure of the operating fluid in the first bypass pilot line and the second bypass pilot line may be the same. Effects of the invention

[0020] According to an embodiment of the present invention, the hydraulic circuit of a construction machine may operate a bypass valve to organically discharge hydraulic fluid from a pump for the operation of a workpiece into a tank, thereby reducing the time difference between the use and stoppage of the workpiece. Brief explanation of the drawing

[0021] FIG. 1 shows a construction machine having a hydraulic circuit arranged therein according to one embodiment of the present invention. FIGS. 2 and FIGS. 3 show a hydraulic circuit of a construction machine according to one embodiment of the present invention. FIG. 4 shows a configuration diagram of a part of a construction machine according to one embodiment of the present invention. Figure 5 shows the conventional joystick operation amount and bypass valve operation amount. FIG. 6 shows the joystick operation amount and the bypass valve operation amount according to one embodiment of the present invention. Specific details for implementing the invention

[0022] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings so that those skilled in the art can easily implement the present invention. The present invention may be embodied in various different forms and is not limited to the embodiments described herein.

[0023] It should be noted that the drawings are schematic and not drawn to scale. The relative dimensions and proportions of parts in the drawings are exaggerated or reduced in size for clarity and convenience, and any dimensions are illustrative only and not limiting. Additionally, the same reference numerals are used to denote similar features for identical structural elements or parts appearing in two or more drawings.

[0024] The embodiments of the present invention specifically illustrate ideal embodiments of the present invention. As a result, various variations of the illustration are expected. Accordingly, the embodiments are not limited to the specific form of the illustrated area and include, for example, variations in form resulting from manufacturing.

[0025] Hereinafter, a hydraulic circuit (102) of a construction machine according to one embodiment of the present invention will be described with reference to FIGS. 1 to 6.

[0026] The construction machine (101) includes a plurality of working devices. Specifically, as shown in FIG. 1, the construction machine (101) includes an upper body (151) on which a driver rides, a lower body (152) that rotates and supports the upper body (151) and drives, a boom (153) that is rotatably supported on the upper body (151), an arm (154) that is rotatably connected to the boom (153), and an attachment (155) that is rotatably connected to the arm (154).

[0027] Additionally, the multiple working devices of the construction machine (101) may include a boom cylinder (130) for driving the boom (153), an arm cylinder (140) for driving the arm (154), a pivot motor (110) for pivoting the upper body (151), a lower body drive device (120) for driving the lower body (152), and a bucket cylinder (150) for driving the attachment (155) if the attachment (155) is a bucket.

[0028] A hydraulic circuit (102) of a construction machine according to one embodiment of the present invention relates to transporting and distributing hydraulic fluid, which is energy for driving a plurality of working machines as described above, as illustrated in FIGS. 2 and FIGS. 3.

[0029] The hydraulic circuit (102) of the construction machine includes a main pump section (200), a first control valve (410), a second control valve (420), a first hydraulic fluid supply line (610), a bypass valve (810), a pilot pump (300), a first pilot valve (510), a second pilot valve (520), a control valve pilot line (710), and a bypass pilot line (720).

[0030] The main pump unit (200) forms hydraulic fluid. Specifically, the main pump unit (200) is operated by the engine (160) and receives power from it to form hydraulic fluid. That is, the main pump unit (200) can generate energy for driving the plurality of work machines described above. The engine (160) provides power for the operation of the main pump unit (200), and the main pump unit (200) can form hydraulic fluid by providing pressure to the hydraulic fluid.

[0031] The first control valve (410) receives hydraulic fluid from the main pump unit (200) and controls one of the multiple working machines. Specifically, the first control valve (410) can transmit hydraulic fluid from the main pump unit (200) to the multiple working machines to transmit the energy required for driving the multiple working machines. Additionally, the first control valve (410) is formed as a switching valve and can supply hydraulic fluid by considering the driving direction of the working machine connected thereto.

[0032] The second control valve (420) receives hydraulic fluid from the main pump unit (200) and controls one of the multiple working machines. Specifically, the second control valve (420) can control a working machine among the multiple working machines that is not controlled by the first control valve (410). Additionally, the second control valve (420) is formed as a switching valve in the same way as the first control valve (410) and can supply hydraulic fluid by considering the driving direction of the working machine connected to the second control valve (420).

[0033] The first hydraulic fluid supply line (610) can guide the movement of hydraulic fluid from the main pump unit (200) to the first control valve (410) and the second control valve (420). Specifically, one side of the first hydraulic fluid supply line (610) may be in communication with the main pump unit (200), and the other side may be in communication with the tank (T). Additionally, hydraulic fluid from the main pump unit (200) can be delivered to the first control valve (410) and the second control valve (420) positioned on this first hydraulic fluid supply line (610). Furthermore, the first hydraulic fluid supply line (610) can guide the hydraulic fluid that has passed through the first control valve (410) and the second control valve (420) to be moved to the tank (T) and recovered.

[0034] A bypass valve (810) is positioned on the first hydraulic fluid supply line (610). Additionally, the bypass valve (810) can selectively open and close the flow path inside the first hydraulic fluid supply line (610). Thus, the bypass valve (810) can be selectively operated to allow the hydraulic fluid passing through the first hydraulic fluid supply line (610) to be recovered into the tank (T).

[0035] Specifically, the bypass valve (810) can allow the hydraulic fluid traveling along the first hydraulic fluid supply line (610) that has passed through the first pilot valve (510) or the second pilot valve (520) to be optionally returned to the tank (T).

[0036] The pilot pump (300) provides pilot pressure. Specifically, the pilot pump (300) can generate pilot pressure from working fluid. For example, the pilot pump (300) may be a gear pump.

[0037] The first pilot valve (510) is connected to the first control valve (410). Additionally, the first pilot valve (510) can be operated by receiving the pilot pressure from the pilot pump (300). Furthermore, the first pilot valve (510) can discharge the pilot pressure to the tank (T) when in neutral. Specifically, the first pilot valve (510) can provide the pilot pressure for switching the first control valve (410).

[0038] The second pilot valve (520) is connected to the second control valve (420). Additionally, the second pilot valve (520) can be operated by receiving the pilot pressure from the pilot pump (300). Furthermore, the second pilot valve (520) can discharge the pilot pressure to the tank (T) when in neutral. Specifically, the second pilot valve (520) can provide the pilot pressure for switching the second control valve (420).

[0039] The control valve pilot line (710) guides the transfer of pilot pressure from the pilot pump (300) to the first pilot valve (510) and the second pilot valve (520). Specifically, the control valve pilot line (710) can transmit the pilot pressure provided by the pilot pump (300) to the first pilot valve (510) and the second pilot valve (520). Additionally, one side of the control valve pilot line (710) may be in communication with the pilot pump (300), and the other side may be in communication with the tank (T). Furthermore, the first pilot valve (510) and the second pilot valve (520) may be positioned on the control valve pilot line (710) to receive and operate the pilot pressure. Additionally, the control valve pilot line (710) can guide the working fluid having the pilot pressure provided by the pilot pump (300) to be returned to the tank (T) when the first pilot valve (510) and the second pilot valve (520) are in a neutral state.

[0040] The bypass pilot line (720) can branch off the pilot pressure provided by the pilot pump (300) and provide it as a pilot pressure for the operation of the bypass valve (810). Specifically, one side of the bypass pilot line (720) may branch off the pilot pressure provided from the pilot pump (300), and the other side may be connected to the bypass valve (810). That is, one side of the bypass pilot line (720) is connected to the control valve pilot line (710) to guide the hydraulic fluid passing through the control valve pilot line (710) to branch off and move.

[0041] Accordingly, the operation of the bypass valve (810) can utilize the pilot pressure supplied to the first pilot valve (510) and the second pilot valve (520) for switching between the first control valve (410) and the second control valve (420). Additionally, the bypass valve (810) is selectively operated according to the pilot pressure passing through the bypass pilot line (720) and can open and close the flow path of the control valve pilot line (710).

[0042] Accordingly, the hydraulic circuit (102) of the construction machine according to one embodiment of the present invention can utilize the pile pressure transmitted to the first pilot valve (510) and the second pilot valve (520) for the operation of the bypass valve (810) by branching it, thus eliminating the need for a separate driving source. Therefore, the hydraulic circuit (102) of the construction machine can be configured simply, and since no separate power source is required, the effect of cost reduction of the construction machine (101) can be achieved.

[0043] In addition, as illustrated in FIG. 2 and FIG. 3, the bypass valve (810) of the hydraulic circuit (102) of a construction machine according to one embodiment of the present invention shares the pilot pressure of the pilot pump (300) supplied to the first pilot valve (510) and the second pilot valve (520), so that it can be linked together according to the operating state of the first pilot valve (510) and the second pilot valve (520), thereby reducing the problem of time difference due to the operation of the bypass valve (810) compared to the case where there is a separate device for operating the bypass valve (810).

[0044] Additionally, if either the first pilot valve (510) or the second pilot valve (520) according to one embodiment of the present invention is not in a neutral state, the bypass valve (810) may be operated.

[0045] If either the first pilot valve (510) or the second pilot valve (520) is not neutral, the flow path of the control valve pilot line (710) that was in communication with the tank (T) can be blocked by either the first pilot valve (510) or the second pilot valve (520) that is not neutral.

[0046] At this time, a pressure of about 30 to 40 bar is applied to the pilot valve in the neutral position between the first pilot valve (510) and the second pilot valve (520). Additionally, by blocking the flow path of the control valve pilot line (710) that was in communication with the tank (T) by either the first pilot valve (510) or the second pilot valve (520) that was not in the neutral position, all of the fluid having the pressure of the pilot pump (300) is delivered to the bypass pilot line (720), so that the bypass valve (810) can be operated (ON).

[0047] That is, as the first pilot valve (510) or the second pilot valve (520) is switched from the neutral state to either side, the hydraulic fluid traveling along the control valve pilot line (710) may be stopped from being discharged into the tank (T). When the first pilot valve (510) or the second pilot valve (520) is not in the neutral state, the high pressure on the control valve pilot line (710) between the pilot pump (300) and the first pilot valve (510) or the second pilot valve (520) is also transmitted to the bypass pilot line (720) so that the bypass valve (810) can be operated.

[0048] Specifically, if either the first pilot valve (510) or the second pilot valve (520) is not in a neutral state, the first control valve (410) or the second pilot valve (520) connected thereto may be switched so that the connected working machine is operated by the hydraulic fluid provided by the main pump unit (200).

[0049] At this time, the bypass valve (810) is operated to close the flow path of the first hydraulic fluid supply line (610), thereby blocking the discharge of pressurized oil that has passed through the switched first control valve (410) or the second control valve (420) into the tank (T). That is, the pressurized oil that has passed through the switched second control valve (420) or the second control valve (420) can be recovered into the tank (T), effectively preventing loss of flow rate.

[0050] Additionally, when the first pilot valve (510) and the second pilot valve (520) according to one embodiment of the present invention are in a neutral state, the bypass valve (810) may not be operated.

[0051] When the first pilot valve (510) and the second pilot valve (520) are in a neutral state, the working fluid discharged from the pilot pump (300) can be recovered to the tank (T) through the control valve pilot line (710). At this time, the pressure of the working fluid passing through the control valve pilot line (710) may be 0 bar.

[0052] Additionally, the pressure of the hydraulic fluid branched from the control valve pilot line (710) is also transmitted to the bypass pilot line (720), and its pressure may also be 0 bar. Therefore, the bypass valve (810) may not operate.

[0053] Specifically, when the bypass valve (810) is not operated, the bypass valve (810) can open the flow path of the first hydraulic fluid supply line (610) to guide the hydraulic fluid passing through it to be recovered into the tank (T). Additionally, when the first pilot valve (510) and the second pilot valve (520) are in a neutral state, the connected work machine may not be operated. Therefore, when both the first control valve (410) and the second control valve (420) are in a neutral state, the hydraulic fluid passing through the first hydraulic fluid supply line (610) can be recovered into the tank (T) by passing through the first control valve (410), the second control valve (420), and the bypass valve (810).

[0054] That is, the hydraulic fluid that passes through the bypass valve (810) and travels along the first hydraulic fluid supply line (610) at the beginning of the start of the construction machine (101) can be recovered into the tank (T), thereby allowing the temperature of the hydraulic fluid to be raised. In this case, the hydraulic circuit (102) of the construction machine can effectively solve the problem of low hydraulic fluid levels depending on the external environment of the construction machine (101).

[0055] In addition, the hydraulic fluid that passes through the bypass valve (810) and travels along the first hydraulic fluid supply line (610) during the initial startup of the construction machine (101) can be recovered into the tank (T), thereby effectively reducing the load applied to the engine due to the rapid increase in rotational speed during engine startup and improving the engine's slow-start performance.

[0056] In addition, the first control valve (410) according to one embodiment of the present invention is a pivot control valve, and the working device connected thereto may be a pivot motor (110).

[0057] When the slewing motor (110) is in operation, as illustrated in FIG. 3, the first control valve (410) and the first pilot valve (510) connected thereto may not remain in a neutral state. Additionally, when the slewing motor (110) is in operation, the hydraulic fluid transmitted from the pilot pump (300) to the first pilot valve (510) through the control valve pilot line (710) may be blocked from being returned to the tank (T) by switching the first pilot valve (510). At this time, the pressure of the pilot pump (300) may be transmitted to the bypass valve (810) through the bypass pilot line (720) to cause the bypass valve (810) to operate. Furthermore, the hydraulic fluid transmitted to the first control valve (410) through the first hydraulic fluid supply line (610) may be prevented from being returned to the tank (T) due to the operation of the bypass valve (810).

[0058] Alternatively, when the slewing motor (110) stops operating (when it stops abruptly), as shown in FIG. 2, the first control valve (410) and the first pilot valve (510) connected thereto may be switched to a neutral state. Also, when the slewing motor (110) stops operating, the hydraulic fluid transmitted from the pilot pump (300) to the first pilot valve (510) through the control valve pilot line (710) may be recovered into the tank (T) by the first pilot valve (510) in the neutral state. At this time, the pressure of the hydraulic fluid passing through the bypass pilot line (720) is 0 bar, so the bypass valve (810) may not operate. And, the hydraulic fluid transmitted to the first control valve (410) through the first hydraulic fluid supply line (610) may be recovered into the tank (T) by not operating the bypass valve (810).

[0059] That is, when the operation of the slewing motor (110) is stopped, the first pilot valve (510), the first control valve (410), and the bypass valve (810) can be operated almost simultaneously without a time delay according to the signal for the individual operation of the valves. As shown in FIGS. 5 and 6, when an operator among a plurality of implements operates the joystick (940) to operate the slewing motor (110), the bypass valve (810) is operated in conjunction with it when the operation is completed. Therefore, the time difference for sending a separate signal for the operation and stoppage of the bypass valve (810) can be reduced.

[0060] Specifically, the amount of bypass valve operation, which is operated by a separate electrical signal according to the amount of joystick operation in the conventional method illustrated in Fig. 5, has a problem in that a delay occurs over time.

[0061] However, the pivoting operation joystick operation amount and the bypass valve operation amount of the hydraulic circuit (102) of the construction machine of the present invention illustrated in FIG. 6 can be operated organically with each other without a time delay. By controlling the control valve using pilot pressure, the bypass valve controlled by the pilot pressure can be effectively controlled.

[0062] That is, the hydraulic circuit (102) of the construction machine of the present invention can solve the problem of delay caused by the time difference that occurs when the signals for controlling the control valve and controlling the bypass valve are different, by using the same control signals for the control valve and the bypass valve.

[0063] Accordingly, the bypass valve (810) can discharge the pressurized oil that has passed through the first hydraulic fluid supply line (610) to the tank (T) according to the operating and stopping state of the slewing motor (110), thereby allowing the make-up flow rate of the slewing motor (110) to be advantageous. Accordingly, the bypass valve (810) can recover the pressurized oil that has passed through the first hydraulic fluid supply line (610) to the tank (T) according to the operating and stopping state of the slewing motor (110), thereby effectively preventing cavitation and chatter even when the slewing motor (110) is stopped abruptly.

[0064] In addition, according to one embodiment of the present invention, the hydraulic circuit (102) of the construction machine may include, as shown in FIG. 2, a first main pump (210), a second main pump (220), a first control valve (410), a second control valve (420), a third control valve (430), a first hydraulic fluid supply line (610), a second hydraulic fluid supply line (620), a first bypass valve (810), a second bypass valve (820), a pilot pump (300), a first pilot valve (510), a second pilot valve (520), a third pilot valve (530), a control valve pilot line (710), a first bypass pilot line (720), and a second bypass pilot line (730).

[0065] The first main pump (210) forms hydraulic fluid. The second main pump (220) forms hydraulic fluid. The first main pump (210) and the second main pump (220) are operated by an engine and receive hydraulic fluid to form hydraulic fluid.

[0066] The first control valve (410) receives pressurized oil from the first main pump (210) and controls one of the plurality of working machines. Specifically, the first control valve (410) provides energy to operate one of the plurality of working machines.

[0067] The second control valve (420) receives pressurized oil from the first main pump (210) and controls one of the multiple working machines. Specifically, the second control valve (420) provides energy to operate one of the multiple working machines.

[0068] The third control valve (430) receives pressurized oil from the second main pump (220) and controls another of the multiple working machines. Specifically, the third control valve (430) provides energy to operate another of the multiple working machines. That is, unlike the first control valve (410) and the second control valve (420), the third control valve (430) receives pressurized oil from the second main pump (220) and can operate the working machine.

[0069] The first hydraulic fluid supply line (610) guides the movement of hydraulic fluid from the first main pump (210) to the first control valve (410) and the second control valve (420). Specifically, one side of the first hydraulic fluid supply line (610) may be in communication with the first main pump (210), and the other side may be in communication with the tank (T). Additionally, the first control valve (410) and the second control valve (420) may be arranged side by side along the first hydraulic fluid supply line (610).

[0070] The first control valve (410) and the second control valve (420) include a neutral position and can be switched according to the direction of sending working fluid to the workpiece.

[0071] The second hydraulic fluid supply line (620) guides the movement of hydraulic fluid from the second main pump (220) to the third control valve (430). Specifically, the first hydraulic fluid supply line (610) may have one side connected to the second main pump (220) and the other side connected to the tank (T). Alternatively, the first hydraulic fluid supply line (610) may be connected such that one side is connected to the second main pump (220) and the other side joins the first hydraulic fluid supply line (610) which is closer to the tank (T) than the first main pump (210). And, the third control valve (430) may be placed on this second hydraulic fluid supply line (620). The third control valve (430) includes a neutral position, just like the first control valve (410) and the second control valve (420) described above, and can be switched according to the direction of sending hydraulic fluid to the connected workpiece.

[0072] The first bypass valve (810) is positioned on the first hydraulic fluid supply line (610). Additionally, the first bypass valve (810) can selectively recover the hydraulic fluid received from the first hydraulic fluid supply line (610) into the tank (T).

[0073] The second bypass valve (820) is positioned on the second hydraulic fluid supply line (620). Additionally, the second bypass valve (820) can selectively recover the hydraulic fluid received from the second hydraulic fluid supply line (620) into the tank (T).

[0074] The pilot pump (300) provides pilot pressure. Specifically, the pilot pump (300) can be operated by an engine to form pressure in the working fluid, thereby providing pilot pressure.

[0075] The first pilot valve (510) is connected to the first control valve (410) and is switched by receiving pilot pressure, and the first control valve (410) can also be switched together. Additionally, the first pilot valve (510) receives pilot pressure and allows the operating fluid provided by the pilot pump (300) to be returned to the tank (T) when in neutral.

[0076] The second pilot valve (520) is connected to the second control valve (420) and is switched by receiving pilot pressure, and the second control valve (420) can also be switched together. Additionally, the second pilot valve (520) receives pilot pressure and allows the operating fluid provided by the pilot pump (300) to be returned to the tank (T) when in neutral.

[0077] The third pilot valve (530) is connected to the third control valve (430) and is switched by receiving pilot pressure, and the third control valve (430) can also be switched together. Additionally, the third pilot valve (530) receives pilot pressure and allows the operating fluid provided by the pilot pump (300) to be returned to the tank (T) when in neutral.

[0078] The control valve pilot line (710) can guide the movement of working fluid provided by the pilot pump (300) from the pilot pump (300) to the first pilot valve (510), the second pilot valve (520), and the third pilot valve (530). Specifically, one side of the control valve pilot line (710) may be in communication with the pilot pump (300), and the other side may be in communication with the tank (T). Additionally, the first pilot valve (510), the second pilot valve (520), and the third pilot valve (530) may be positioned on the control valve pilot line (710). That is, the pilot valves for switching control valves that transfer energy from different main pumps to the working machine may receive pilot pressure through the control valve pilot line (710).

[0079] The first bypass pilot line (720) can branch and deliver the operating fluid provided by the pilot pump (300) for the operation of the first bypass valve (810). Specifically, one side of the first bypass pilot line (720) is branched from the control valve pilot line (710), and the other side can be connected to the first bypass valve (810). Additionally, the pressure of the operating fluid delivered to the first bypass valve (810) along the first bypass pilot line (720) can be used as a pilot pressure to selectively operate the first bypass valve (810).

[0080] The second bypass pilot line (730) can branch and deliver the operating fluid provided by the pilot pump (300) for the operation of the second bypass valve (820). Specifically, one side of the second bypass pilot line (730) is branched from the control valve pilot line (710), and the other side can be connected to the second bypass valve (820). Additionally, the pressure of the operating fluid delivered to the second bypass valve (820) along the second bypass pilot line (730) can be used as a pilot pressure to selectively operate the second bypass valve (820).

[0081] Accordingly, the first bypass valve (810), the second bypass valve (820), and the first, second, and third control valves (410, 420, 430) can be organically controlled according to the pressure of the hydraulic fluid provided by the pilot pump (300). Accordingly, the hydraulic circuit (102) of the construction machine of the present invention can be organically controlled without a delay in signaling for operation between the first bypass valve (810), the second bypass valve (820), and the first, second, and third control valves (410, 420, 430).

[0082] Additionally, when any of the first pilot valve (510), the second pilot valve (520), and the third pilot valve (530) is not in a neutral state, the first bypass valve (810) and the second bypass valve (820) can each be operated (ON). Specifically, when the first bypass valve (810) is operated, the first bypass valve (810) can close the flow path of the first hydraulic fluid supply line (610) to block the recovery of pressurized oil from the first main pump (210) to the tank (T). Additionally, when the second bypass valve (820) is operated, the second bypass valve (820) can close the flow path of the second hydraulic fluid supply line (620) to block the recovery of pressurized oil from the second main pump (220) to the tank (T).

[0083] Additionally, a pressure of about 30 to 40 bar is applied to the control valve pilot line (710) and the non-neutral valve among the first pilot valve (510), the second pilot valve (520), and the third pilot valve (530), so that any one of the first pilot valve (510), the second pilot valve (520), and the third pilot valve (530) remains in a non-neutral state. That is, the recovery of the operating fluid supplied by the pilot pump (300) to the tank (T) through the control valve pilot line (710) can be blocked.

[0084] The pressure of the hydraulic fluid on the control valve pilot line (710) can provide hydraulic pressure to the first bypass pilot line (720) and the second bypass pilot line (730) branched from it, so that the pressure of the hydraulic fluid on the control valve pilot line (710) is transmitted to the first bypass pilot line (720) and the second bypass pilot line (730), respectively, so that the first bypass valve (810) and the second bypass valve (820) are operated. Then, the first bypass valve (810) can block the hydraulic fluid of the first main pump (210) that has passed through the first hydraulic fluid supply line (610) from being returned to the tank (T). Additionally, the second bypass valve (820) can block the hydraulic fluid of the second main pump (220) that has passed through the second hydraulic fluid supply line (620) from being returned to the tank (T).

[0085] In addition, when the first pilot valve (510), the second pilot valve (520), and the third pilot valve (530) according to one embodiment of the present invention are all in a neutral state, the pressure of the hydraulic fluid passing through the control valve pilot line (710) and the pressure of the hydraulic fluid in the first bypass pilot line (720) and the first bypass pilot line (720) can be the same.

[0086] At this time, the operating fluid provided by the pilot pump (300) passing through the control valve pilot line (710) can be recovered to the tank (T) by passing through the first pilot valve (510), the second pilot valve (520), and the third pilot valve (530) which are in a neutral state. Therefore, the pressure of the operating fluid provided by the pilot pump (300) passing through the control valve pilot line (710) can be 0 bar. Also, the same pressure can be applied to the first bypass pilot line (720) and the second bypass pilot line (730) which branch off from the control valve pilot line (710) and receive the operating fluid.

[0087] Accordingly, the first bypass valve (810) and the second bypass valve (820) are not operated, and the hydraulic fluid passing through the first control valve (410) and the second control valve (420) along the first hydraulic fluid supply line (610) can be recovered into the tank (T) through the first bypass valve (810). At this time, the hydraulic fluid passing through the third control valve (430) along the second hydraulic fluid supply line (620) can be recovered into the tank (T) through the second bypass valve (820).

[0088] Hereinafter, with reference to FIGS. 1 to 4, the operation process of a hydraulic circuit of a construction machine according to an embodiment of the present invention will be explained.

[0089] The construction machine (101) may include a plurality of working parts, such as a boom cylinder (130), an arm cylinder (140), a slewing motor (110), a driving device (120), and a bucket cylinder (150).

[0090] And, the hydraulic circuit (102) of the construction machine may include a first control valve (410), a second control valve (420), a third control valve (430), a fourth control valve (440), a fifth control valve (450), a sixth control valve (460), a seventh control valve (470), an eighth control valve (480), and a ninth control valve (490).

[0091] As previously described, the first control valve (410), the second control valve (420), the fourth control valve (440), the fifth control valve (450), and the sixth control valve (460) are arranged side by side on the first hydraulic fluid supply line (610) to receive hydraulic fluid from the first main pump (210). Specifically, the sixth control valve (460) is positioned at the uppermost position based on the flow of hydraulic fluid discharged from the first main pump (210) on the first hydraulic fluid supply line (610), and subsequently, the fifth control valve (450), the first control valve (410), the second control valve (420), the fourth control valve (440), and the first bypass valve (810) can be arranged sequentially.

[0092] Additionally, the third control valve (430), the seventh control valve (470), the eighth control valve (480), and the ninth control valve (490) are arranged side by side on the second hydraulic fluid supply line (620) as described above to receive hydraulic fluid from the second main pump (220). Specifically, the ninth control valve (490) is positioned at the uppermost position based on the flow of hydraulic fluid discharged from the second main pump (220) on the second hydraulic fluid supply line (620), and the third control valve (430), the eighth control valve (480), the seventh control valve (470), and the second bypass valve (820) can be arranged sequentially thereafter.

[0093] The fourth control valve (440) and the seventh control valve (470) can supply hydraulic fluid for the operation of the arm cylinder (140).

[0094] The second control valve (420) and the eighth control valve (480) can supply hydraulic fluid for the operation of the boom cylinder (130).

[0095] The first control valve (410) can supply hydraulic fluid for the operation of the slewing motor (110).

[0096] The fifth control valve (450) can supply hydraulic fluid for operation when a backup device of the construction machine (101) is installed.

[0097] The 6th control valve (460) and the 9th control valve (490) can supply hydraulic fluid for the operation of the drive unit (120).

[0098] Additionally, the hydraulic circuit (102) of the construction machine may include a first pilot valve (510), a second pilot valve (520), a third pilot valve (530), a fourth pilot valve (540), a fifth control pilot valve (5450), a sixth pilot valve (560), a seventh pilot valve (570), an eighth pilot valve (580), and a ninth pilot valve (590). These may be connected to their respective control valves, such as the first, second, and third pilot valves (510, 520, 530) described above.

[0099] On the control valve pilot line (710), a sixth pilot valve (560) is positioned at the uppermost level based on the flow of the pilot pump (300), and subsequently, a fifth pilot valve (550), a first pilot valve (510), a second pilot valve (520), a fourth pilot valve (540), a seventh pilot valve (570), an eighth pilot valve (580), a third pilot valve (530), and a ninth pilot valve (590) can be sequentially positioned. The control valve pilot line (710) behind the ninth pilot valve (590) can be positioned to communicate with the tank (T).

[0100] As shown in FIG. 2, both the first pilot valve (510) and the ninth pilot valve (590) are in a neutral state. At this time, the operating fluid supplied from the pilot pump (300) and moving the first pilot valve (510) and the ninth pilot valve (590) to the neutral position along the control valve pilot line (710) is recovered into the tank (T).

[0101] At this time, the hydraulic fluid branched from the control valve pilot line (710) travels along the first bypass pilot line (720) and the second bypass pilot line (730). And, the pressure of the hydraulic fluid traveled along the first bypass pilot line (720) and the second bypass pilot line (730) does not operate the first bypass valve (810) and the second bypass valve (820), respectively.

[0102] Accordingly, the first bypass valve (810) keeps the flow path of the first hydraulic fluid supply line (610) open, so that the hydraulic fluid of the first main pump (210) supplied through the first hydraulic fluid supply line (610) is recovered into the tank (T). Additionally, the second bypass valve (820) keeps the flow path of the second hydraulic fluid supply line (620) open, so that the hydraulic fluid of the second main pump (220) supplied through the second hydraulic fluid supply line (620) is recovered into the tank (T).

[0103] That is, when the first control valve (410) to the ninth control valve (490) are in the neutral position, the pressurized oil supplied from the first main pump (210) and the second main pump (220) can be recovered into the tank (T). This allows the pressurized oil to be recovered and circulated into the tank (T) when the first control valve (410) to the ninth control valve (490) are in the neutral position, thereby increasing the temperature of the pressurized oil when the temperature of the operating oil is low due to the external environment during the initial engine start.

[0104] As illustrated in FIG. 3, the first pilot valve (510) is switched from a neutral position to a unidirectional position, and the first control valve (410) connected thereto supplies the operating fluid of the first main pump (210) for the rotation of the slewing motor (110) connected thereto. The switching of the first pilot valve (510) can be performed by receiving a signal from the joystick (940) to select the valve to be switched among a plurality of pilot valves. Specifically, as illustrated in FIG. 4, the control unit (950) receives a signal from the joystick (940) and can select the operating status of the first main pump (210), the second main pump (220), and the pilot pump (300), as well as the pilot valve that requires switching among a plurality of pilot valves. The joystick (940) is operated by an operator, and the information thereof can be transmitted to the control unit (950).

[0105] At this time, the pilot pump (300) provides pilot pressure to the first pilot valve (510) so that the first control valve (410) is switched, and the pressure provided by the pilot pump (300) on the control valve pilot line (710) between the first pilot valve (510) and the pilot pump (300) can be formed to 30 bar to 40 bar. This is because, due to the one-way switching from the neutral position of the first pilot valve (510), the flow of hydraulic fluid provided by the pilot pump (300) is blocked even if the second pilot valve (520) located downstream of the first pilot valve (510) is in a neutral state. That is, as the one-way switching from the neutral position of the first pilot valve (510) is blocked, the hydraulic fluid of the operating fluid provided by the pilot pump (300) can be blocked from being recovered into the tank (T).

[0106] Then, the pressure of the hydraulic fluid branched from the control valve pilot line (710) is branched and transmitted through the first bypass pilot line (720) and the second bypass pilot line (730). Then, the first bypass valve (810) and the second bypass valve (820) are operated by the pressure of the hydraulic fluid transmitted to the hydraulic portions of the first bypass valve (810) and the second bypass valve (820) through the first bypass pilot line (720) and the second bypass pilot line (730).

[0107] Accordingly, the first bypass valve (810) is operated to prevent the pressurized oil supplied from the first main pump (210) supplied to the first hydraulic oil supply line (610) from being recovered into the tank (T) through the first hydraulic oil supply line (610) after passing through the first bypass valve (810).

[0108] Additionally, the second bypass valve (820) is operated to prevent the pressurized oil supplied from the second main pump (220) supplied to the second hydraulic oil supply line (620) from being recovered into the tank (T) through the second hydraulic oil supply line (620) after passing through the second bypass valve (820).

[0109] Accordingly, the operating fluid of the first main pump (210) can be effectively delivered without loss for the operation of the slewing motor (110) connected to the first control valve (410).

[0110] And, if FIG. 3 shows the operating state of the slewing motor (110) and FIG. 2 shows the sudden stop of the slewing motor (110), the first bypass valve (810), the second bypass valve (820), the first pilot valve (510), and the first control valve (410) can be operated organically, so that the time delay can be effectively reduced compared to the case where signals are provided for the separate operation of the valves.

[0111] In addition, the hydraulic circuit (102) of a construction machine according to one embodiment of the present invention, as shown in FIG. 2, can open the first hydraulic fluid supply line (610) and the second hydraulic fluid supply line (620) so that the hydraulic fluid supplied from the main pump unit (200) is recovered to the tank (T) when the first control valve (410), the second control valve (420), the third control valve (430), the fourth control valve (440), the fifth control valve (450), the sixth control valve (460), the seventh control valve (470), the eighth control valve (480), and the ninth control valve (490) are in a neutral state.

[0112] In this case, even if the temperature of the hydraulic fluid is low, the pressurized oil supplied from the main pump unit (200) by the first bypass valve (810) or the second bypass valve (820) is recovered into the tank (T), and the temperature of the hydraulic fluid can be increased. Specifically, the construction machine (101) may further include a temperature sensor (960) to detect the temperature of the hydraulic fluid discharged from the main pump unit (200), but when a plurality of control valves are in a neutral state (not in an operating state), the first hydraulic fluid supply line (610) or the second hydraulic fluid supply line (620) may be kept open by the first bypass valve (810) or the second bypass valve (820), thereby increasing the temperature of the hydraulic fluid.

[0113] In addition, the hydraulic circuit (102) of a construction machine according to one embodiment of the present invention, as shown in FIG. 2, allows the first control valve (410), the second control valve (420), the third control valve (430), the fourth control valve (440), the fifth control valve (450), the sixth control valve (460), the seventh control valve (470), the eighth control valve (480), and the ninth control valve (490) to maintain a neutral state during the initial start of the engine (160), so that the first bypass valve (810) opens the first hydraulic fluid supply line (610) and the second bypass valve (820) opens the second hydraulic fluid supply line (620) so that the hydraulic fluid supplied from the main pump unit (200) is recovered to the tank (T).

[0114] Accordingly, the hydraulic circuit (102) of the construction machine can open the first hydraulic fluid supply line (610) and the second hydraulic fluid supply line (620) by the first bypass valve (810) so that the hydraulic fluid supplied from the main pump unit (200) is returned to the tank (T) when there is no operation signal transmission of the work machine by a separate joystick (940) during the initial start of the engine (160). In this case, the load applied to the engine (160) can be reduced.

[0115] In addition, the hydraulic circuit (102) of a construction machine according to one embodiment of the present invention, as shown in FIG. 2, allows the first control valve (410), the second control valve (420), the third control valve (430), the fourth control valve (440), the fifth control valve (450), the sixth control valve (460), the seventh control valve (470), the eighth control valve (480), and the ninth control valve (490) to maintain a neutral state when the operator selects the emergency mode. At this time, the first bypass valve (810) can open the first hydraulic fluid supply line (610) and the second bypass valve (820) can open the second hydraulic fluid supply line (620) so that the hydraulic fluid supplied from the main pump unit (200) is recovered to the tank (T). Therefore, when the operator selects the emergency mode, the first bypass valve (810) and the second bypass valve (820) can effectively prevent malfunctions such as operating multiple control valves due to pressure caused by a failure.

[0116] In addition, in the hydraulic circuit (102) of a construction machine according to one embodiment of the present invention, when the first control valve (410), the second control valve (420), the third control valve (430), the fourth control valve (440), the fifth control valve (450), the sixth control valve (460), the seventh control valve (470), the eighth control valve (480), and the ninth control valve (490) are maintained in a neutral state, the first bypass valve (810) opens the first hydraulic fluid supply line (610) and the second bypass valve (820) opens the second hydraulic fluid supply line (620) so that the hydraulic fluid supplied from the main pump unit (200) is recovered to the tank (T), thereby effectively preventing malfunctions such as pressure causing a constant failure operating multiple control valves.

[0117] Accordingly, the hydraulic circuit (102) of a construction machine according to one embodiment of the present invention can organically control the pilot valve, control valve, and bypass valve without time delay by utilizing the operating fluid of the pilot pump (300), thereby reducing the time delay for operating the valves.

[0118] Although embodiments of the present invention have been described above with reference to the attached drawings, those skilled in the art to which the present invention pertains will understand that the present invention may be implemented in other specific forms without changing its technical concept or essential features.

[0119] Therefore, the embodiments described above should be understood as illustrative in all respects and not limiting, and the scope of the invention is defined by the claims set forth below, and all modifications or variations derived from the meaning and scope of the claims and equivalents thereof should be interpreted as being included within the scope of the invention. Explanation of the symbols

[0120] 200: Main pump section 210: 1st main pump 220: Second main pump 300: Pilot pump 410: 1st control valve 420: 2nd control valve 430: Third control valve 510: 1st pilot valve 520: 2nd pilot valve 530: 3rd Pilot Valve 610: 1st hydraulic fluid supply line 620: 2nd hydraulic fluid supply line 710: Control valve pilot line 720: First bypass pilot line, bypass pilot line 730: 2nd Bypass Pilot Line T: Tank 810: 1st bypass valve, bypass valve 820: 2nd bypass valve 110: Slewing motor 102: Hydraulic circuit of construction machinery

Claims

Claim 1 A hydraulic circuit of a construction machine that operates multiple implements of the construction machine, comprising: a main pump unit that forms hydraulic fluid; a first control valve that receives hydraulic fluid from the main pump unit and controls one of the multiple implements; a second control valve that receives hydraulic fluid from the main pump unit and controls another of the multiple implements; a first hydraulic fluid supply line that guides the movement of hydraulic fluid from the main pump unit to the first control valve, the second control valve, and a tank; a bypass valve disposed on the first hydraulic fluid supply line and capable of selectively opening and closing the hydraulic fluid moving to the tank; a pilot pump that provides pilot hydraulic fluid; a control valve pilot line that guides the movement of hydraulic fluid from the pilot pump to the tank; a first pilot valve disposed on the control valve pilot line and connected to the first control valve; and a second pilot valve disposed on the control valve pilot line and connected to the second control valve. A hydraulic circuit of a construction machine, comprising a bypass pilot line capable of branching and transmitting pilot pressure for the operation of the bypass valve, and wherein, when either the first pilot valve or the second pilot valve is not in a neutral state, the pilot pressure provided by the pilot pump is transmitted to the bypass pilot line to operate the bypass valve. Claim 2 A hydraulic circuit of a construction machine according to claim 1, further comprising an engine that provides operating power for the main pump unit, and characterized in that the bypass valve opens the first hydraulic fluid supply line when the engine starts. Claim 3 A hydraulic circuit of a construction machine according to claim 1, characterized in that when the first control valve and the second control valve are in a neutral state, the bypass valve opens the first hydraulic fluid supply line to prevent the first control valve and the second control valve from malfunctioning. Claim 4 A hydraulic circuit of a construction machine according to claim 1, characterized in that when the first control valve and the second control valve are in a neutral state, the bypass valve opens the first hydraulic fluid supply line so that the hydraulic fluid supplied from the main pump moves to the tank and raises the temperature of the hydraulic fluid. Claim 5 delete Claim 6 A hydraulic circuit of a construction machine according to claim 1, characterized in that when a working machine connected to the first control valve is operated, the bypass valve is operated to prevent the hydraulic fluid passing through the first operating fluid supply line from moving to the tank. Claim 7 A hydraulic circuit of a construction machine according to claim 1, characterized in that when the first pilot valve and the second pilot valve are in a neutral state, the bypass valve is not operated. Claim 8 A hydraulic circuit of a construction machine according to claim 1, wherein the first control valve is a swing control valve, the working machine connected to the first control valve is a swing motor, and the bypass valve is operated when the swing motor is operated, and the bypass valve can be switched so as not to operate when the operation of the swing motor is stopped. Claim 9 A hydraulic circuit of a construction machine according to claim 1, characterized in that when the bypass valve is operated, the hydraulic oil passing through the first hydraulic oil supply line is prevented from moving to the tank, and when the bypass valve is not operated, the hydraulic oil passing through the first hydraulic oil supply line is moved to the tank. Claim 10 In a hydraulic circuit of a construction machine that operates multiple implements of the construction machine, the hydraulic circuit comprises: a first main pump that forms hydraulic fluid; a second main pump that forms hydraulic fluid; a first control valve that receives hydraulic fluid from the first main pump and controls one of the multiple implements; a second control valve that receives hydraulic fluid from the first main pump and controls another of the multiple implements; a third control valve that receives hydraulic fluid from the second main pump and controls yet another of the multiple implements; a first hydraulic fluid supply line that guides the movement of hydraulic fluid from the first main pump to the first control valve and the second control valve; a second hydraulic fluid supply line that guides the movement of hydraulic fluid from the second main pump to the third control valve; a first bypass valve disposed on the first hydraulic fluid supply line and capable of selectively opening and closing the flow of hydraulic fluid received from the first hydraulic fluid supply line to a tank; and a second hydraulic fluid supply line disposed on the second hydraulic fluid supply line and selectively opening and closing the flow of hydraulic fluid received from the second hydraulic fluid supply line to a tank A second bypass valve capable of opening and closing the flow; a pilot pump that forms and provides pilot pressure to the working fluid; a first pilot valve connected to the first control valve, receiving pilot pressure and allowing the working fluid provided by the pilot pump to move to a tank when neutral; a second pilot valve connected to the second control valve, receiving pilot pressure and allowing the working fluid provided by the pilot pump to move to a tank when neutral; a third pilot valve connected to the third control valve, receiving pilot pressure and allowing the working fluid provided by the pilot pump to move to a tank when neutral; and a control valve pilot line that guides the movement of the working fluid provided by the pilot pump from the pilot pump to the first pilot valve, the second pilot valve, and the third pilot valve.A hydraulic circuit of a construction machine comprising: a first bypass pilot line capable of branching and delivering hydraulic fluid provided by the pilot pump for the operation of the first bypass valve; and a second bypass pilot line capable of branching and delivering hydraulic fluid provided by the pilot pump for the operation of the second bypass valve, wherein when the first pilot valve, the second pilot valve, and the third pilot valve are all in neutral, the pressure of the hydraulic fluid passing through the control valve pilot line and the pressure of the hydraulic fluid in the first bypass pilot line and the second bypass pilot line are the same. Claim 11 A hydraulic circuit of a construction machine according to claim 10, characterized in that when any one of the first pilot valve, the second pilot valve, and the third pilot valve is not in a neutral state, the first bypass valve is operated to close the first hydraulic fluid supply line and the second bypass valve is operated to close the second hydraulic fluid supply line. Claim 12 delete

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