Engineering machinery, hydraulic system and control method thereof

Abstract

and a control method thereof. The hydraulic system comprises a hydraulic tank, a main pump, an auxiliary pump, a pilot oil source block, a multi-way valve and an actuator; the oil outlet of the main pump is connected to the first oil inlet of the multi-way valve, the oil outlet of the auxiliary pump is connected to the second oil inlet of the multi-way valve, and the first oil inlet and the second oil inlet of the multi-way valve are communicated; the oil outlet of the main pump is connected to the oil inlet of the pilot oil source block, the oil outlet of the pilot oil source block is connected to the pilot oil port of the multi-way valve, and the oil return port of the pilot oil source block is communicated with the hydraulic tank; the pilot oil source block has a built-in solenoid valve, when the solenoid valve is energized, the solenoid valve core is in a first position, and the oil outlet of the pilot oil source block is communicated with the oil inlet of the pilot oil source block through the solenoid valve; when the solenoid valve is de-energized, the solenoid valve core is in a second position, and the oil outlet of the pilot oil source block is communicated with the oil return port of the pilot oil source block through the solenoid valve; the main pump and the auxiliary pump both comprise an electrically controlled variable pump, a variable displacement mechanism, a displacement sensor and a pressure sensor.

Description

Technical Field

[0001] The present invention relates to an engineering machine, a hydraulic system and a control method thereof, and belongs to the technical field of engineering machinery. Background Art

[0002] As users demand increasingly higher levels of efficiency, safety, response speed, and energy consumption from machinery and equipment, each system is undergoing optimization and upgrades to enhance performance and meet these requirements. Hydraulic systems are a key component of construction machinery, consuming the majority of the equipment's power. While the evolution from fixed-displacement hydraulic systems to variable-displacement hydraulic systems has led to increasing energy efficiency and efficiency, variable-displacement systems also have drawbacks compared to fixed-displacement systems. Changing the displacement of a variable pump from minimum to maximum requires a certain response time, and this response time is further extended if the pump's displacement is controlled by a multi-way valve. Increases in hydraulic system power are limited by the power available from the power source. Currently, hydraulic systems lack real-time matching with the power source, resulting in inadequate utilization of the power source and achieving maximum efficiency. Excessive system power can also lead to power source failure. Research on energy efficiency in hydraulic systems has been limited to improving system principles, with insufficient utilization of the high-efficiency zones of hydraulic components, particularly pumps, resulting in energy losses. Summary of the Invention

[0003] Purpose: To overcome the deficiencies in the prior art, the present invention provides an engineering machine, a hydraulic system and a control method thereof.

[0004] Technical solution: To solve the above technical problems, the technical solution adopted by the present invention is:

[0005] In a first aspect, a hydraulic system is provided, comprising a hydraulic oil tank, a main pump, an auxiliary pump, a pilot oil source block, a multi-way valve, and an actuator;

[0006] The oil suction ports of the main pump and the auxiliary pump are connected to the hydraulic oil tank respectively; the oil outlet of the main pump is connected to the first oil inlet P1 of the multi-way valve, and the oil outlet of the auxiliary pump is connected to the second oil inlet P2 of the multi-way valve. The first oil inlet P1 and the second oil inlet P2 of the multi-way valve are connected inside the multi-way valve, and each working port of the multi-way valve is connected to the corresponding actuator respectively.

[0007] The pilot oil source block is provided with an oil inlet P3, an oil outlet C, and an oil return port T2. The main pump oil outlet is connected to the pilot oil source block oil inlet P3, the pilot oil source block oil outlet C is connected to the pilot oil port PP of the multi-way valve, and the pilot oil source block oil return port T2 is connected to the hydraulic oil tank;

[0008] The pilot oil source block has a built-in solenoid valve, which has a first position and a second position. When the solenoid valve is energized, the solenoid valve core is in the first position, and the oil outlet C of the pilot oil source block is connected to the oil inlet P3 of the pilot oil source block through the solenoid valve; when the solenoid valve is de-energized, the solenoid valve core is in the second position, and the oil outlet C of the pilot oil source block is connected to the oil return port T2 of the pilot oil source block through the solenoid valve;

[0009] The main pump and auxiliary pump both include an electronically controlled variable pump, a displacement mechanism, a displacement sensor and a pressure sensor. The displacement sensor and pressure sensor are installed at the outlet of the electronically controlled variable pump. One end of the displacement mechanism is connected to the pressure sensor for receiving the pressure signal of the electronically controlled variable pump, and the other end is connected to the swash plate of the electronically controlled variable pump for changing the pump displacement.

[0010] In some embodiments, the multi-way valve is a closed-center multi-way valve or an open-center multi-way valve, and the multi-way valve is controlled by electro-hydraulic proportional control.

[0011] Furthermore, the multi-way valve has a first oil inlet P1, a second oil inlet P2, first working ports A1, B1 and second working ports A2, B2, a pilot oil port PP, a return port T, and an oil drain port D; the actuator includes a first actuator and a second actuator;

[0012] The first working ports A1 and B1 of the multi-way valve are connected to the first actuator, and the second working ports A2 and B2 of the multi-way valve are connected to the second actuator; the return port T and the oil drain port D are respectively connected to the hydraulic oil tank.

[0013] In some embodiments, the actuator is a hydraulic cylinder.

[0014] In some embodiments, the hydraulic system further includes a main one-way valve, and the oil outlet of the main pump is connected to the first oil inlet P1 of the multi-way valve through the main one-way valve.

[0015] In some embodiments, the hydraulic system further includes an auxiliary one-way valve, and the auxiliary pump oil outlet is connected to the second oil inlet P2 of the multi-way valve through the auxiliary one-way valve.

[0016] In some embodiments, the pilot oil source block also includes a throttle valve, a filter, a pressure reducing valve, a one-way valve, and an accumulator. The oil at the oil inlet P3 of the pilot oil source block passes through the throttle valve, the filter, the pressure reducing valve, and the one-way valve in sequence and is stored in the accumulator, and then is connected to the oil outlet C of the pilot oil source block through the solenoid valve. The oil outlet C of the pilot oil source block is connected to the return oil port T2 through the solenoid valve; the pressure reducing valve is connected to the return oil port T2.

[0017] In a second aspect, a control method for the hydraulic system is provided, comprising:

[0018] In response to manipulation, the total displacement is calculated based on the manipulation signal and the power source speed, and the total displacement is distributed to the main pump and auxiliary pump according to certain rules. The output displacement of the main pump and auxiliary pump is controlled so that the main pump and auxiliary pump operate in the high-efficiency area.

[0019] Furthermore, the control method of the hydraulic system further includes:

[0020] Obtain the actual pressure and flow of the main pump and auxiliary pump;

[0021] The total power of the hydraulic system is calculated based on the actual pressure and actual flow of the main pump and auxiliary pump; the corresponding power source power is obtained based on the power source speed;

[0022] Compare the total power of the hydraulic system with the power source power;

[0023] In response to a ratio of the total power of the hydraulic system to the power of the power source exceeding a preset range, the displacement of the main pump and the auxiliary pump are correspondingly controlled to be reduced.

[0024] According to a third aspect, an engineering machine is provided, comprising the above-mentioned hydraulic system.

[0025] Beneficial effects: The hydraulic system provided by the present invention adopts a pump group to supply oil, a pilot oil source block to provide pilot oil for the multi-way valve, and an electrical signal to simultaneously control the reversing of the multi-way valve and the oil supply of the pump group to realize the action of the actuator. During operation, the size of the electrical signal is used to control the opening size of the multi-way valve core and the oil supply size of the pump group. The pump group coordinates the output of each pump according to the system pressure and system flow, and makes full use of the high-efficiency area of the pump. The system pressure and system flow are obtained by the pressure sensor arranged at the pump outlet, the displacement sensor on the pump body and the power source speed information. At the same time, the total power of the hydraulic system can be calculated by the system pressure and system flow, and compared with the power source power. Whether the power of the power source is too high or exceeds the high-efficiency working area of the power source, the flow of the hydraulic system is adjusted accordingly, so that the system has the advantages of energy saving, high efficiency, fast response and safety. It has the following advantages:

[0026] Energy saving: On the one hand, the speed of the actuator is controlled by the pump output, eliminating the throttling losses of a quantitative system, where excess flow must overflow through the valve core. This eliminates the valve core pressure loss of a load-sensitive fully variable system, where the valve core must form a throttling mechanism to provide feedback to the pump to control flow, resulting in a constant pressure loss in the system. The novel hydraulic system described in this invention provides flow according to system requirements and does not require valve core throttling to generate a feedback signal to control pump flow, thus reducing energy loss. Furthermore, a pump group control method is employed, assigning different flow control levels to different pumps, fully utilizing the efficient working area of each pump and reducing energy loss.

[0027] High efficiency, the pump integrates displacement sensor, pressure sensor, combined with power source speed information, can monitor the hydraulic system power in real time, maximize the use of power source power, improve system efficiency, and prevent the hydraulic system power from exceeding the power source output power, preventing power source failure.

[0028] Fast response, the system controller directly controls the pump and multi-way valve at the same time. Compared with the load-sensitive system controller that controls the multi-way valve, the multi-way valve then feeds back the signal to the pump, and the pump responds according to the feedback signal, which saves the time of multi-way valve feedback and greatly improves the responsiveness.

[0029] Safety design: a solenoid valve is installed at the outlet of the pilot oil source block to cut off the pilot oil supply to the multi-way valve, effectively preventing safety hazards caused by misoperation. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic diagram of a hydraulic system according to an embodiment of the present invention;

[0031] Figure 2 This is a schematic diagram of the main pump in the embodiment;

[0032] Figure 3 This is a schematic diagram of the auxiliary pump in the embodiment;

[0033] Figure 4 This is a schematic diagram of the pilot oil source block in the embodiment;

[0034] In the figure: hydraulic oil tank 1, main pump 2, auxiliary pump 3, main check valve 4, auxiliary check valve 5, pilot oil source block 6, multi-way valve 7, actuator 1 8, actuator 2 9;

[0035] A first pump 21, a first displacement sensor 22, a first pressure sensor 23, and a first displacement changing mechanism 24;

[0036] A second pump 31, a second displacement sensor 32, a second pressure sensor 33, and a second displacement changing mechanism 34;

[0037] Throttle valve 61 , filter 62 , pressure reducing valve 63 , check valve 64 , accumulator 65 , solenoid valve 66 . DETAILED DESCRIPTION

[0038] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0039] Unless otherwise specifically stated, the relative arrangement of the parts and steps, the numerical expressions and the numerical values set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be understood that, for ease of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship. The techniques, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the techniques, methods and equipment should be considered as part of the authorization specification. In all examples shown and discussed here, any specific values should be interpreted as being merely exemplary and not as limiting. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following figures, and therefore, once an item is defined in one figure, it does not need to be further discussed in subsequent figures.

[0040] Example 1

[0041] like Figure 1 As shown, a hydraulic system includes a hydraulic oil tank 1, a main pump 2, an auxiliary pump 3, a pilot oil source block 6, a multi-way valve 7, and an actuator;

[0042] The oil suction ports of the main pump 2 and the auxiliary pump 3 are respectively connected to the hydraulic oil tank 1; the oil outlet of the main pump 2 is connected to the first oil inlet P1 of the multi-way valve 7, and the oil outlet of the auxiliary pump 3 is connected to the second oil inlet P2 of the multi-way valve 7. The first oil inlet P1 and the second oil inlet P2 of the multi-way valve 7 are connected inside the multi-way valve 7, and each working port of the multi-way valve 7 is respectively connected to the corresponding actuator;

[0043] like Figure 1 、 Figure 4 As shown, the pilot oil source block 6 is provided with an oil inlet P3, an oil outlet C, and an oil return port T2. The oil outlet of the main pump 2 is connected to the oil inlet P3 of the pilot oil source block 6, the oil outlet C of the pilot oil source block 6 is connected to the pilot oil port PP of the multi-way valve 7, and the oil return port T2 of the pilot oil source block 6 is connected to the hydraulic oil tank 1;

[0044] The pilot oil source block 6 has a built-in solenoid valve 66, which has a first position and a second position. When the solenoid valve 66 is energized, the solenoid valve core is in the first position, and the oil outlet C of the pilot oil source block 6 is connected to the oil inlet P3 of the pilot oil source block 6 through the solenoid valve 66; when the solenoid valve 66 is de-energized, the solenoid valve core is in the second position, and the oil outlet C of the pilot oil source block 6 is connected to the oil return port T2 of the pilot oil source block 6 through the solenoid valve 66.

[0045] Further, such as Figure 4As shown, the pilot oil source block 6 also includes a throttle valve 61, a filter 62, a pressure reducing valve 63, a one-way valve 64, and an accumulator 65. The oil at the oil inlet P3 of the pilot oil source block 6 passes through the throttle valve 61, the filter 62, the pressure reducing valve 63, the one-way valve 64 in sequence and is stored in the accumulator 65, and then is connected to the oil outlet C of the pilot oil source block 6 through the solenoid valve 66. The oil outlet C of the pilot oil source block 6 is connected to the return oil port T2 through the solenoid valve 66; the pressure reducing valve 63 is connected to the return oil port T2.

[0046] The main pump 2 and the auxiliary pump 3 both include an electronically controlled variable pump, a displacement mechanism, a displacement sensor and a pressure sensor. The displacement sensor and the pressure sensor are installed at the outlet of the electronically controlled variable pump. One end of the displacement mechanism is connected to the pressure sensor for receiving the pressure signal of the electronically controlled variable pump, and the other end is connected to the swash plate of the electronically controlled variable pump for changing the pump displacement.

[0047] like Figure 2 As shown in the figure, it is the internal principle diagram of the main pump 2, and the connection method is as follows: the first displacement sensor 22 and the first pressure sensor 23 are installed at the outlet of the first pump 21. One end of the first displacement changing mechanism 24 is connected to the first pressure sensor 23 for receiving the pressure signal of the first pump 21, and the other end is connected to the swash plate of the first pump 21 to push the swash plate to achieve the purpose of changing the pump displacement. The stronger the signal, the greater the pump displacement.

[0048] Similarly, if Figure 3 Figure 2 shows the internal schematic diagram of the auxiliary pump 3. The connection method is as follows: a second displacement sensor 32 and a second pressure sensor 33 are installed at the outlet of the second pump 31. One end of the second displacement changing mechanism 34 is connected to the second pressure sensor 33 for receiving the pressure signal of the second pump 31, and the other end is connected to the swash plate of the second pump 31 to drive the swash plate to achieve the purpose of changing the pump displacement. The stronger the signal, the greater the pump displacement.

[0049] In some embodiments, the multi-way valve 7 is a closed-center multi-way valve or an open-center multi-way valve, and the multi-way valve is controlled by electro-hydraulic proportional control.

[0050] In some embodiments, the multi-way valve 7 has a first oil inlet P1, a second oil inlet P2, a first working port A1, B1 and a second working port A2, B2, a pilot oil port PP, a return port T, and an oil drain port D; the actuator includes a first actuator 8 and a second actuator 9; the first working ports A1 and B1 of the multi-way valve 7 are respectively connected to the rodless chamber and the rod chamber of the first actuator 8, and the second working ports A2 and B2 of the multi-way valve 7 are respectively connected to the rodless chamber and the rod chamber of the second actuator 9; the return port T and the oil drain port D are respectively connected to the hydraulic oil tank 1.

[0051] In some embodiments, the actuator includes but is not limited to a hydraulic cylinder.

[0052] In some embodiments, the hydraulic system further includes a main check valve 4, through which the oil outlet of the main pump 2 is connected to the first oil inlet P1 of the multi-way valve 7. The system further includes an auxiliary check valve 5, through which the oil outlet of the auxiliary pump 3 is connected to the second oil inlet P2 of the multi-way valve 7.

[0053] Example 2

[0054] The control method of the hydraulic system in the above embodiment includes:

[0055] In response to manipulation, the total displacement is calculated based on the manipulation signal and the power source speed, and the total displacement is distributed to the main pump 2 and the auxiliary pump 3 according to certain rules. The output displacement of the main pump 2 and the auxiliary pump 3 is controlled so that the main pump 2 and the auxiliary pump 3 operate in the high-efficiency area.

[0056] Furthermore, it also includes:

[0057] Obtain the actual pressure and actual flow of the main pump 2 and the auxiliary pump 3; calculate the hydraulic system pressure based on the actual pressure of the main pump 2 and the auxiliary pump 3; calculate the total power of the hydraulic system based on the actual pressure and actual flow of the main pump 2 and the auxiliary pump 3; obtain the corresponding power source power based on the power source speed;

[0058] In response to the hydraulic system pressure reaching a set value, comparing the total power of the hydraulic system with the power of the power source;

[0059] In response to the ratio of the total power of the hydraulic system to the power of the power source exceeding a preset range, the displacement of the main pump 2 and the auxiliary pump 3 is correspondingly controlled to be reduced.

[0060] Start the equipment. When there is no operation, the oil enters the main pump 2 and the auxiliary pump 3 from the hydraulic oil tank 1, and enters the multi-way valve 7 through the main check valve 4 and the auxiliary check valve 5 respectively. Since there is no operation, the valve core of the multi-way valve 7 is in the middle position, and the oil from the main pump 2 and the auxiliary pump 3 is sealed at the valve core inlet, and the pressure gradually rises. Since there is no operation, the controller controls the pump displacement according to the pump port pressure, so that the pump port is maintained at the standby pressure. If the pump port pressure is lower than the standby pressure, the pump displacement is reduced. If the pump port pressure is higher than the standby pressure, the pump displacement is increased, and the output flow only meets the leakage in the system. At the same time, part of the oil from the oil outlet of the main pump 2 enters the pilot oil source block 6, passes through the throttle valve 61, filter 62, pressure reducing valve 63, and one-way valve 64 inside it, and is stored in the accumulator 65. It is then connected to the pilot oil port PP of the multi-way valve 7 through the built-in solenoid valve 66 of the pilot oil source block 6, providing the multi-way valve 7 with pilot oil to drive the valve core movement. At this time, the oil in the pilot oil source block 6 does not flow without manipulation.

[0061] The solenoid valve 66 in the pilot oil source block 6 is controlled by a separate switch. When the solenoid valve 66 in the pilot oil source block 6 is energized, the valve core is in the upper position, and the pilot oil in the pilot oil source block 6 can enter the multi-way valve 7. When the control signal is given to the multi-way valve 7, the pilot oil enters the corresponding control chamber, driving the valve core to move. When the solenoid valve 66 in the pilot oil source block 6 is de-energized, the valve core is in the lower position, and the pilot oil port PP of the multi-way valve 7 is connected to the hydraulic oil tank 1 through the solenoid valve in the pilot oil source block 6. At this time, even if the control signal is given to the multi-way valve 7, without the pilot oil, the valve core of the multi-way valve 7 cannot be switched, and the actuator 1 or actuator 2 will not operate, thus avoiding the danger caused by misoperation.

[0062] When the device is started and actuator 1 (8) is operated, oil flows from the hydraulic tank (1) into the main pump (2) and auxiliary pump (3), and then into the multi-way valve (7) through the main check valve (4) and auxiliary check valve (5), respectively. Due to the operation, the multi-way valve (7) controls the valve core of actuator 1 to the working position. Oil from the main pump (2) and auxiliary pump (3) flows through these valve cores into actuator 1, causing actuator 1 to produce the corresponding action. The oil flow rate depends on the control signal; a larger control signal increases the flow rate. Specifically, the controller calculates the corresponding total displacement based on the power source speed. This displacement is then distributed between the main pump (2) and auxiliary pump (3) according to a specific rule, fully utilizing the pump's efficient operating range and reducing energy consumption. As the load changes and the system pressure reaches a certain value, the controller calculates the current system power using the first pressure sensor (23) and first displacement sensor (22) of the main pump (2) and the second pressure sensor (33) and second displacement sensor (32) of the auxiliary pump (3). When the system power exceeds a certain percentage of the power source power or there is a risk of power source failure, the controller reduces the displacement of the main pump (2) and auxiliary pump (3) until the programmed setting is met. Maximize the power source power, improve system efficiency, and avoid power source failure. When operating the second actuator 9, the system action is the same as above, and only the actuator 1 8 needs to be replaced with the actuator 2 9.

[0063] Example 3

[0064] On the other hand, an engineering machine is also provided, comprising the above-mentioned hydraulic system.

[0065] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A hydraulic system, characterized in that: It includes a hydraulic oil tank, a main pump, an auxiliary pump, a pilot oil source block, a multi-way valve, and an actuator; the suction ports of the main pump and the auxiliary pump are respectively connected to the hydraulic oil tank; the outlet of the main pump is connected to the first inlet P1 of the multi-way valve, the outlet of the auxiliary pump is connected to the second inlet P2 of the multi-way valve, the first inlet P1 and the second inlet P2 of the multi-way valve are connected inside the multi-way valve, and each working port of the multi-way valve is respectively connected to the corresponding actuator; the pilot oil source block is provided with an inlet P3, an outlet C, and a return port T2, the outlet of the main pump is connected to the inlet P3 of the pilot oil source block, the outlet C of the pilot oil source block is connected to the pilot oil port PP of the multi-way valve, and the return port T2 of the pilot oil source block is connected to the hydraulic oil tank; the pilot oil source block is internally provided with a solenoid valve, the solenoid valve has a first position and a second position, when the solenoid valve is powered on, the solenoid valve spool is located at the first position, and the outlet C of the pilot oil source block is导通 to the inlet P3 of the pilot oil source block through the solenoid valve; when the solenoid valve is de-energized, the solenoid valve spool is located at the second position, and the outlet C of the pilot oil source block is connected to the return port T2 of the pilot oil source block through the solenoid valve; both the main pump and the auxiliary pump include an electronically controlled variable pump, a variable displacement mechanism, a displacement sensor, and a pressure sensor. The outlet of the electronically controlled variable pump is equipped with a displacement sensor and a pressure sensor. One end of the variable displacement mechanism is connected to the pressure sensor to receive the pressure signal of the electronically controlled variable pump, and the other end is connected to the swash plate of the electronically controlled variable pump to change the pump displacement; The control method of the hydraulic system includes: in response to manipulation, calculating the total displacement according to the manipulation signal and the power source speed, distributing the total displacement to the main pump and the auxiliary pump according to certain rules, and controlling the output displacements of the main pump and the auxiliary pump to make the main pump and the auxiliary pump operate in the high-efficiency area; it also includes: obtaining the actual pressure and actual flow of the main pump and the auxiliary pump; calculating the total power of the hydraulic system according to the actual pressure and actual flow of the main pump and the auxiliary pump; obtaining the corresponding power source power according to the power source speed; comparing the total power of the hydraulic system with the power source power; in response to the ratio of the total power of the hydraulic system to the power source power exceeding the preset range, correspondingly controlling to reduce the displacements of the main pump and the auxiliary pump.

2. The hydraulic system according to claim 1, characterized in that: The multi-way valve is a closed-center multi-way valve or an open-center multi-way valve, and the control of the multi-way valve adopts electro-hydraulic proportional control.

3. The hydraulic system according to claim 1, characterized in that: The multi-way valve has a first inlet P1, a second inlet P2, a first working port A1, B1, a second working port A2, B2, a pilot oil port PP, a return port T, and a drain port D; the actuator includes a first actuator and a second actuator; The first working ports A1, B1 of the multi-way valve are connected to the first actuator, and the second working ports A2, B2 of the multi-way valve are connected to the second actuator; the return port T and the drain port D are respectively connected to the hydraulic oil tank.

4. The hydraulic system according to claim 1, characterized in that: The actuator is a hydraulic cylinder.

5. The hydraulic system according to claim 1, characterized in that: It also includes a main check valve, and the outlet of the main pump is connected to the first inlet P1 of the multi-way valve through the main check valve.

6. The hydraulic system according to claim 1, characterized in that: It also includes an auxiliary check valve, and the outlet of the auxiliary pump is connected to the second inlet P2 of the multi-way valve through the auxiliary check valve.

7. The hydraulic system according to claim 1, characterized in that: The pilot oil source block also includes a throttle valve, a filter, a pressure reducing valve, a one-way valve, and an accumulator. The oil at the oil inlet P3 of the pilot oil source block passes through the throttle valve, the filter, the pressure reducing valve, and the one-way valve in sequence and is stored in the accumulator, and then is connected to the oil outlet C of the pilot oil source block through the solenoid valve. The oil outlet C of the pilot oil source block is connected to the return oil port T2 through the solenoid valve; the pressure reducing valve is connected to the return oil port T2.

8. An engineering machine, characterized in that: Comprising the hydraulic system according to any one of claims 1 to 7.

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