Hydraulic system and working machine

Abstract

The application relates to the technical field of working machines, and provides a hydraulic system and a working machine for controlling a hydraulic actuator of the working machine, which comprises a first hydraulic pump, a second hydraulic pump, a valve assembly and a control device, the first hydraulic pump and the second hydraulic pump are connected with the hydraulic actuator through a first oil supply oil way and a second oil supply oil way respectively; and the control device is used for controlling the valve assembly to alternately guide the first oil supply oil way and the second oil supply oil way. The first hydraulic pump and the second hydraulic pump can be alternately controlled by the control device to supply oil to the hydraulic actuator, the working time length of a single pump in a single time period is reduced, and the service life of the whole hydraulic pump is prolonged.

Description

Technical Field

[0001] This invention relates to the field of work machinery technology, and in particular to a hydraulic system and work machinery. Background Technology

[0002] Currently, more and more excavators are being used in various fields. The application of hydraulic breakers in demolishing old buildings, concrete roads, and mining is increasing. Compared to bucket operation, the main pump pressure of an excavator switches between high and low pressure more frequently and at higher amplitudes when working in breaking conditions. Prolonged operation under breaking conditions is very harmful to the main pump. Because existing large excavators use a dual-pump system, where both pumps drive the hydraulic breaker simultaneously, the frequent pressure switching between high and low pressure during breaking operations can easily lead to damage over time. If one pump fails, the entire main pump becomes unusable, thus reducing its lifespan. Summary of the Invention

[0003] This invention provides a hydraulic system and operating machinery to solve the defects in the prior art where the two pumps of the excavator's dual pump drive the breaker hammer to work at the same time, which is prone to damage after long-term operation. If one pump fails, the entire main pump will become unusable, thus reducing the service life.

[0004] This invention provides a hydraulic system for controlling the hydraulic actuators of working machinery, comprising a first hydraulic pump, a second hydraulic pump, a valve assembly, and a control device, wherein...

[0005] The first hydraulic pump and the second hydraulic pump are respectively connected to the hydraulic actuator through the first oil supply line and the second oil supply line;

[0006] The control device is used to control the valve assembly to alternately activate the first oil supply circuit and the second oil supply circuit.

[0007] A hydraulic system according to the present invention further includes:

[0008] A timing module is used to record the duration of oil supply from the first hydraulic pump and / or the second hydraulic pump to the hydraulic actuator;

[0009] The control device is communicatively connected to the timing module, and the control device is used to control the valve assembly according to the oil supply duration recorded by the timing module.

[0010] According to a hydraulic system provided by the present invention, the control device includes:

[0011] Control valve assembly;

[0012] The control unit is communicatively connected to the timing module and the control valve group, and controls the control valve group based on the oil supply duration recorded by the timing module.

[0013] A hydraulic system according to the present invention further includes:

[0014] The time input module is used to set the preset duration;

[0015] The control device is communicatively connected to the time input module, and the control device can control the valve assembly to switch the oil supply circuit when the oil supply duration recorded by the timing module reaches the preset duration.

[0016] According to a hydraulic system provided by the present invention, the valve assembly includes:

[0017] The first valve is used to control the opening or closing of the first oil supply circuit;

[0018] The second valve is used to control the opening or closing of the second oil supply circuit;

[0019] The control device is used to control the opening and closing of the first valve and the second valve.

[0020] According to a hydraulic system provided by the present invention, a main valve is further included, wherein the first hydraulic pump and the second hydraulic pump are respectively connected to the main valve through a first bypass oil passage and a second bypass oil passage.

[0021] According to a hydraulic system provided by the present invention, the pilot port of the main valve and the pilot port of the valve assembly are connected to the outlet port of the control valve group.

[0022] According to a hydraulic system provided by the present invention, the main valve includes a first signal shut-off valve and a second signal shut-off valve, wherein,

[0023] The first signal shut-off valve is used to control the opening or closing of the first bypass oil circuit, and the second signal shut-off valve is used to control the opening or closing of the second bypass oil circuit.

[0024] The control device is used to control the opening and closing of the first signal shut-off valve and the second signal shut-off valve.

[0025] The present invention also provides a working machine, including a hydraulic actuator and a hydraulic system as described in any of the preceding claims.

[0026] According to the present invention, the hydraulic actuator of the operating machine is a hydraulic breaker.

[0027] The hydraulic system and operating machinery provided by the present invention can switch the conduction of the control valve assembly through the control device, so that the first hydraulic pump and the second hydraulic pump can alternately supply oil to the hydraulic actuator. This can reduce the working time of a single pump in a single time period, which is beneficial to extending the service life of the first hydraulic pump and the second hydraulic pump, thereby improving the service life of the main pump. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of the hydraulic system structure provided by the present invention.

[0030] Figure label:

[0031] 1: Hydraulic oil tank; 2: Hydraulic breaker; 3: First hydraulic pump;

[0032] 4: Second hydraulic pump; 5: Main valve; 6: Valve assembly;

[0033] 7: Control valve assembly; 8: Inlet shut-off valve; 9: Return shut-off valve;

[0034] 10: Filter; 51: First signal shut-off valve; 52: Second signal shut-off valve;

[0035] 61: First valve; 62: Second valve; 63: Relief valve. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0037] The following is combined with Figure 1 The present invention describes a hydraulic system and a working machine.

[0038] like Figure 1 As shown, the hydraulic system provided by the present invention is used to control the hydraulic actuator of a working machine. The hydraulic system includes a first hydraulic pump 3, a second hydraulic pump 4, a valve assembly 6, and a control device.

[0039] The first hydraulic pump 3 and the second hydraulic pump 4 are connected to the hydraulic actuator through the first oil supply circuit and the second oil supply circuit, respectively, to supply oil to the hydraulic actuator.

[0040] Valve assembly 6 is used to control the first and second oil supply circuits. Specifically, valve assembly 6 can control the opening or closing of the first and second oil supply circuits, thus allowing the first hydraulic pump 3 and the second hydraulic pump 4 to supply oil to the hydraulic actuator independently. Furthermore, the control device controls valve assembly 6 to alternately open the first and second oil supply circuits, thereby allowing the first hydraulic pump 3 and the second hydraulic pump 4 to alternately supply oil to the hydraulic actuator.

[0041] With this configuration, the control valve assembly 6 can be used to alternately supply oil to the hydraulic actuator via the first hydraulic pump 3 and the second hydraulic pump 4. This reduces the working time of a single pump within a single time period, which helps to extend the service life of the first hydraulic pump 3 and the second hydraulic pump 4, thereby improving the service life of the entire main pump.

[0042] In an optional embodiment of the present invention, the valve assembly 6 may include a first valve 61 and a second valve 62. The first valve 61 is used to control the opening or closing of the first oil supply circuit, and the second valve 62 is used to control the opening or closing of the second oil supply circuit. Furthermore, a control device is used to control the opening and closing of the first valve 61 and the second valve 62; that is, the control device can control the opening or closing of the first oil supply circuit and the second oil supply circuit respectively through the first valve 61 and the second valve 62.

[0043] In this way, by controlling the opening and closing states of the first valve 61 and the second valve 62, the first hydraulic pump 3 and the second hydraulic pump 4 can alternately supply oil to the hydraulic actuator, thereby improving the service life of the first hydraulic pump 3 and the second hydraulic pump 4.

[0044] In this embodiment, both the first valve 61 and the second valve 62 can be directional valves.

[0045] In other embodiments, valve assembly 6 may include a two-position three-way directional valve, which is used to connect to the first oil supply circuit and the second oil supply circuit. The control device controls the opening or closing of the first oil supply circuit and the second oil supply circuit by controlling the opening state of the two-position three-way directional valve, so as to realize that the first hydraulic pump 3 and the second hydraulic pump 4 alternately supply oil to the hydraulic actuator.

[0046] Here, the two-position three-way directional valve is a two-inlet-one-outlet directional valve. The first inlet of the two-position three-way directional valve is connected to the first oil supply circuit, the second inlet is connected to the second oil supply circuit, and the oil outlet of the two-position three-way directional valve is used to connect to the hydraulic actuator.

[0047] In an optional embodiment, valve assembly 6 may further include a relief valve 63, the inlet of which is connected to the outlet of the first valve 61 and the second valve 62, and the outlet of the relief valve 63 is connected to the hydraulic oil tank 1. In this way, the relief valve 63 can prevent excessive pressure on the hydraulic actuator, thus protecting the hydraulic actuator and improving its service life.

[0048] Here, the overflow valve 63 can be installed at the oil outlet of the first valve 61 and the second valve 62 on the breaking pipeline of the hydraulic actuator.

[0049] In an optional embodiment of the present invention, the hydraulic system may further include a timing module, which is used to record the duration of oil supply to the hydraulic actuator by the first hydraulic pump 3 and / or the second hydraulic pump 4.

[0050] The control device can communicate with the timing module. The control device controls the valve assembly 6 to switch the oil supply circuit according to the oil supply duration recorded by the timing module, allowing the first and second oil supply circuits to alternately operate. This allows the first hydraulic pump 3 and the second hydraulic pump 4 to work alternately after a certain period, thereby reducing the operating time of a single pump within a single time period.

[0051] It should be noted that the timing module can record the opening time of the first valve 61 and the second valve 62, so as to determine the oil supply duration of the first hydraulic pump 3 and the second hydraulic pump 4 to the hydraulic actuator by recording the opening time of the first valve 61 and the second valve 62.

[0052] In an optional embodiment, the hydraulic system may further include a time input module for setting a preset duration. The control device is communicatively connected to the time input module, and when the oil supply duration recorded by the timing module reaches the preset duration, the control device can switch the valve assembly 6 to conduct, causing the first and second oil supply circuits to alternately operate. This allows the first hydraulic pump 3 and the second hydraulic pump 4 to work alternately after the preset operating duration, thereby reducing the operating time of a single pump within a single time period.

[0053] Here, the timing module can be a timer, and the time input module can be a mechanical keyboard or buttons.

[0054] In an optional embodiment, the control device may include a control valve group 7 and a control unit. The control valve group 7 is used to control the valve assembly 6. The control unit is communicatively connected to the timing module and the control valve group 7. The control unit can control the control valve group 7 based on the oil supply duration recorded by the timing module, so that the control valve group 7 controls the valve assembly 6 to switch on.

[0055] Here, the time input module can communicate with the control unit, and the control unit can include a comparison module. The comparison module is used to compare the oil supply duration recorded by the timing module with the preset duration and can send the comparison result to the control unit. The control unit controls the control valve group 7 to send a control signal to control the valve assembly 6 based on the comparison result.

[0056] It should be noted that the control unit can be a controller or a control circuit board. Specifically, the controller can be a PLC controller or a microcontroller controller, or other devices or equipment capable of automatic control. No specific limitation is made to the control unit here, and it can be set according to actual needs.

[0057] In an optional embodiment of the present invention, the hydraulic system further includes a main valve 5, and a first hydraulic pump 3 and a second hydraulic pump 4 are respectively connected to the main valve 5 through a first bypass oil passage and a second bypass oil passage, so that the first hydraulic pump 3 and the second hydraulic pump 4 can supply oil to the main valve 5, so that the main valve 5 can supply oil to other oil-using equipment, thereby ensuring the normal operation of other oil-using equipment.

[0058] The main valve 5 may include a first signal shut-off valve 51 and a second signal shut-off valve 52. The first signal shut-off valve 51 is used to control the opening or closing of the first bypass oil circuit, and the second signal shut-off valve 52 is used to control the opening or closing of the second bypass oil circuit.

[0059] Furthermore, the control device is used to control the opening and closing of the first signal shut-off valve 51 and the second signal shut-off valve 52, thereby controlling the opening or closing of the first bypass oil circuit and the second bypass oil circuit.

[0060] Specifically, the control valve group 7 can control the first signal cut-off valve 51 to close, so that the first signal cut-off valve 51 controls the first bypass oil circuit to be cut off, so that the oil in the first hydraulic pump 3 cannot flow into the main valve 5; the control valve group 7 can control the second signal cut-off valve 52 to close, so that the second signal cut-off valve 52 controls the second bypass oil circuit to be cut off, so that the oil in the second hydraulic pump 4 cannot flow into the main valve 5.

[0061] Here, the main valve may include a first valve block and a second valve block. The first valve block is connected to the first hydraulic pump 3 via a first bypass oil circuit, and the second valve block is connected to the second hydraulic pump 4 via a second bypass oil circuit. Thus, the first hydraulic pump 3 and the second hydraulic pump 4 can supply oil to the first valve block and the second valve block respectively, so as to supply oil to other oil-using components through the main valve 5, ensuring that the other oil-using components can operate normally. The first signal shut-off valve 51 can shut off the first valve block, preventing it from conducting and thus cutting off the first bypass oil circuit; the second signal shut-off valve 52 can shut off the second valve block, preventing it from conducting and thus cutting off the second bypass oil circuit, preventing oil from the first hydraulic pump 3 and the second hydraulic pump 4 from flowing into the main valve 5.

[0062] In this embodiment, when the operating machinery is in crushing operation, when the control device controls the first valve 61 to open, the first oil supply circuit is opened, causing the first hydraulic pump 3 to supply oil to the breaker 2. At this time, the control device controls the first signal cut-off valve 51 to close, causing the first signal cut-off valve 51 to cut off the first valve block, causing the first hydraulic pump 3 to stop supplying oil to the first valve block, thereby stopping the supply of oil to the main valve 5, so that the first hydraulic pump 3 can only supply oil to the hydraulic actuator; or, when the control device controls the second valve 62 to open, the second oil supply circuit is opened, causing the second hydraulic pump 4 to supply oil to the breaker 2. At this time, the control device controls the second signal cut-off valve 52 to close, causing the second signal cut-off valve 52 to cut off the second valve block, causing the second hydraulic pump 4 to stop supplying oil to the second valve block, thereby stopping the supply of oil to the main valve 5, so that the second hydraulic pump 4 can only supply oil to the hydraulic actuator.

[0063] In an optional embodiment, the hydraulic breaker port of the main valve 5 is a closed port, so that when the first hydraulic pump 3 or the second hydraulic pump 4 supplies oil to the main valve 5, it will not supply oil to the hydraulic breaker 2 through the main valve 5.

[0064] In some embodiments, after receiving a start signal from the hydraulic actuator, such as after receiving a start signal from the hydraulic breaker 2, the control unit controls the control valve group 7 to control the valve assembly 6, thereby opening the first oil supply circuit and causing the first hydraulic pump 3 to start supplying oil to the hydraulic actuator. At this time, the timing module records the duration of the first oil supply circuit (i.e., the opening time of the first valve 61). When the working time recorded by the timing module is greater than or equal to the preset duration, the control unit controls the control valve group 7 to switch the control valve assembly 6 to open, thereby opening the second oil supply circuit and causing the second hydraulic pump 4 to start supplying oil to the hydraulic actuator. Alternatively, when the control unit receives the start signal of the hydraulic actuator, it controls the control valve group 7 to control the valve assembly 6, thus opening the second oil supply circuit and causing the second hydraulic pump 4 to start supplying oil to the hydraulic actuator. At this time, the timing module records the duration of the second oil supply circuit (i.e., the opening time of the second valve 62). When the working time recorded by the timing module is greater than or equal to the preset duration, the control valve group 7 switches the control valve assembly 6 to open, causing the first hydraulic pump 3 to start supplying oil to the hydraulic actuator. In this way, the first hydraulic pump 3 and the second hydraulic pump 4 can work alternately.

[0065] Here, when the control valve group 7 controls the control valve assembly 6 to switch directions, the timing module starts to reset the timing to ensure that the oil supply time of the first hydraulic pump 3 and the second hydraulic pump 4 is the same, thereby improving the service life of the first hydraulic pump 3 and the second hydraulic pump 4.

[0066] Furthermore, in this embodiment, when the control unit does not receive a start signal from the hydraulic actuator, i.e. when the hydraulic actuator is not working, the control unit controls the control valve group 7 to lock the valve core of the control valve assembly 6, i.e., it can control both the first valve 61 and the second valve 62 to be in a closed state, so that neither the first hydraulic pump 3 nor the second hydraulic pump 4 can supply oil to the hydraulic actuator through the valve assembly 6.

[0067] The pilot port of the main valve 5 and the pilot port of the valve assembly 6 are both connected to the outlet of the control valve group 7.

[0068] Specifically, the control valve assembly 7 may include a first control valve and a second control valve. The outlet of the first control valve can be connected to the pilot port of the first valve 61 and the pilot port of the first signal shut-off valve 51. Thus, by supplying hydraulic oil (i.e., pilot oil) to the first valve 61 and the first signal shut-off valve 51 through the first control valve, the first valve 61 controls the first oil supply circuit to open, and the first signal shut-off valve 51 closes, thus cutting off the first bypass oil circuit. The outlet of the second control valve can be connected to the pilot port of the second valve 62 and the pilot port of the second signal shut-off valve 52. Thus, by supplying hydraulic oil to the second valve 62 and the second signal shut-off valve 52 through the second control valve, the second valve 62 controls the second oil supply circuit to open, and the second signal shut-off valve 52 closes, thus cutting off the second bypass oil circuit.

[0069] Here, both the first control valve and the second control valve are communicatively connected to the control unit, and both the first control valve and the second control valve can be solenoid valves.

[0070] The control valve group 7 can be a two-way solenoid valve group, that is, the first control valve and the second control valve are combined to form a two-way solenoid valve group. The two solenoid valves of the two-way solenoid valve group are interlocked, which helps to improve the control accuracy of the control valve group 7 and improve the safety factor of the control valve group 7 and the valve assembly 6.

[0071] In other embodiments, one-way valves can be provided on both the first oil supply line and the second oil supply line. The conduction direction of the two one-way valves is consistent with the direction from the first hydraulic pump 3 to the first valve 61 and the direction from the second hydraulic pump 4 to the second valve 62, respectively. This can prevent oil backflow.

[0072] An oil inlet shut-off valve 8 is installed on the breaking pipeline of the hydraulic breaker 2, and a return oil shut-off valve 9 and a filter 10 are installed on the return oil pipeline of the hydraulic breaker 2. Here, the return oil pipeline of the hydraulic breaker 2 is connected to the hydraulic oil tank 1.

[0073] The hydraulic system provided by this invention allows the control unit to, upon receiving the start signal of the hydraulic breaker 2 (i.e., when the excavator switches to the breaking mode), control the two-way solenoid valve group to send a first working signal DC1 to the valve assembly 6 and to send a signal to the first signal cut-off valve 51, causing the first signal cut-off valve 51 to close and the first valve block to be de-conductive. Based on the received first working signal DC1, the first valve 61 of the valve assembly 6 opens, connecting the first oil supply circuit and allowing the first hydraulic pump 3 to supply oil to the hydraulic breaker 2. Simultaneously, the timing module begins recording the opening time of the first valve 61 to record the oil supply time t1 of the first hydraulic pump 3 to the hydraulic actuator, until the working time recorded by the timing module equals the preset time t2. When the working time recorded by the timing module equals the preset time t2, the control unit controls the two-way solenoid valve group to send a second working signal DC2 to the valve assembly 6 and to send a signal to the second signal cut-off valve 52, causing the second signal cut-off valve 52 to close and the second valve block to be de-conductive. Based on the received second working signal DC2, the second valve 62 of the valve assembly 6 opens, connecting the second oil supply circuit and allowing the second hydraulic pump 4 to supply oil to the breaker 2. Simultaneously, the timing module restarts the timing to record the oil supply time of the second hydraulic pump 4 to the hydraulic actuator, until the working time recorded by the timing module equals the preset time t2. The control unit then controls the two-way solenoid valve group to send a first working signal DC1 to the valve assembly 6 again, controlling the valve assembly 6 to switch directions again, realizing the alternating operation of the first hydraulic pump 3 and the second hydraulic pump 4.

[0074] When the control unit receives the start signal of the hydraulic breaker 2 (such as a signal to restart after a power outage), if the oil supply time of the hydraulic pump (such as the first hydraulic pump 3) to the hydraulic actuator recorded by the timing module is less than the preset time, the control unit controls the two solenoid valve groups to send the working signal corresponding to the hydraulic pump to the valve assembly 6, causing the valve corresponding to the hydraulic pump in the valve assembly 6 to open (such as the first valve 61 of the valve assembly 6 to open). This continues until the working time recorded by the timing module reaches the preset time. Then, the control unit controls the two solenoid valve groups to send the working signal corresponding to the other hydraulic pump to the valve assembly 6, controlling the valve corresponding to the other hydraulic pump in the valve assembly 6 to open (such as the second valve 62 of the valve assembly 6 to open), so that the other hydraulic pump supplies oil to the hydraulic breaker 2. This helps to ensure that the oil supply time of the two hydraulic pumps to the hydraulic actuator is consistent, thereby improving the service life of the two hydraulic pumps.

[0075] The working machinery provided by the present invention is described below. The working machinery described below can be referred to in correspondence with the hydraulic system described above.

[0076] The present invention provides a working machine, including a hydraulic actuator and a hydraulic system as described in any of the above embodiments.

[0077] The beneficial effects achieved by the working machinery provided by this invention are consistent with the beneficial effects achieved by the hydraulic system provided by this invention, so they will not be repeated here.

[0078] In an optional embodiment of the present invention, the hydraulic actuator described above may be a hydraulic breaker.

[0079] It should be noted that the aforementioned operating machinery can be excavators, pump trucks, or other construction machinery equipped with hydraulic actuators.

[0080] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Those skilled in the art can understand and implement this without any creative effort.

[0081] Through the above description of the embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus necessary general-purpose hardware platform, or of course by hardware.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A hydraulic system, characterized in that, A hydraulic actuator for controlling machinery includes a first hydraulic pump, a second hydraulic pump, a valve assembly, a main valve, and a control device, wherein the first hydraulic pump and the second hydraulic pump are connected to the hydraulic actuator via a first oil supply line and a second oil supply line, respectively. The control device controls the valve assembly to alternately open the first oil supply circuit and the second oil supply circuit; The first hydraulic pump and the second hydraulic pump are connected to the main valve through the first bypass oil circuit and the second bypass oil circuit, respectively. The main valve supplies oil to other oil-using equipment, and the crushing oil port of the main valve is a closed oil port. The main valve includes a first signal shut-off valve and a second signal shut-off valve, wherein the first signal shut-off valve controls the opening or closing of the first bypass oil circuit, and the second signal shut-off valve controls the opening or closing of the second bypass oil circuit. The control device controls the opening and closing of the first signal shut-off valve and the second signal shut-off valve.

2. The hydraulic system according to claim 1, characterized in that, Also includes: The timing module records the duration of oil supply from the first hydraulic pump and / or the second hydraulic pump to the hydraulic actuator. The control device is communicatively connected to the timing module, and the control device is used to control the valve assembly according to the oil supply duration recorded by the timing module.

3. The hydraulic system according to claim 2, characterized in that, The control device includes: Control valve assembly; The control unit is communicatively connected to the timing module and the control valve group, and controls the control valve group based on the oil supply duration recorded by the timing module.

4. The hydraulic system according to claim 2, characterized in that, Also includes: The time input module is used to set the preset duration; The control device is communicatively connected to the time input module, and the control device can control the valve assembly to switch the oil supply circuit when the oil supply duration recorded by the timing module reaches the preset duration.

5. The hydraulic system according to claim 1, characterized in that, The valve assembly includes: The first valve controls the opening or closing of the first oil supply circuit; The second valve controls the opening or closing of the second oil supply circuit; The control device controls the opening and closing of the first valve and the second valve.

6. The hydraulic system according to claim 3, characterized in that, The pilot port of the main valve and the pilot port of the valve assembly are connected to the outlet port of the control valve group.

7. A type of operating machinery, characterized in that, Includes hydraulic actuators and hydraulic systems as described in any one of claims 1-6.

8. The operating machinery according to claim 7, characterized in that, The hydraulic actuator is a hydraulic breaker.

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