Hydraulic system and engineering machinery

Abstract

The invention relates to a hydraulic system and engineering machinery, the hydraulic system comprises a multi-way valve, a first hydraulic pump and a cooler, the first hydraulic pump conveys oil in an oil tank into the multi-way valve, an oil inlet of the cooler is communicated with a working oil port of the multi-way valve, and an oil outlet of the cooler is communicated with the oil tank; the cooler is used for cooling oil flowing from a working oil port of the multi-way valve to the oil tank, and an oil inlet of the cooler is communicated with the working oil port of the multi-way valve. According to the hydraulic system, oil conveyed into the multi-way valve by the first hydraulic pump can directly enter the cooler through the working oil port of the multi-way valve communicated with the cooler, the flow entering the cooler tends to be stable relatively, and the flow of the oil entering the cooler by the hydraulic system is large, so that the circulation efficiency of the oil passing through the cooler is high; and the cooling effect of the cooler on oil in the hydraulic system is improved.

Description

Technical Field

[0001] The present disclosure relates to the field of engineering machinery and equipment, and in particular, to a hydraulic system and engineering machinery. Background Art

[0002] During the operation of a concrete pump truck, the temperature of the hydraulic system will rise, and the oil in the hydraulic system needs to be cooled by a cooler. In the related art, the cooler is installed on the return oil circuit of the hydraulic system, and the return oil circuits of the hydraulic circuits responsible for various functions in the hydraulic system of the concrete pump truck are cooled by the cooler before entering the oil tank. However, the return oil circuits of each hydraulic circuit are connected to the cooler. Usually, when the mechanism controlled by the hydraulic circuit is in operation, the amount of oil flowing into the cooler from the return oil circuit of the circuit is larger. When the mechanism controlled by the hydraulic circuit is not in operation, the oil in the return oil circuit of the hydraulic circuit that enters the cooler is relatively small, or even close to zero. This results in an unstable flow of the oil entering the cooler, and the circulation efficiency of the oil passing through the cooler is low, which reduces the cooling effect of the cooler on the oil in the hydraulic system. Summary of the invention

[0003] The purpose of the present disclosure is to provide a hydraulic system and engineering machinery, in which the hydraulic system connects the working oil port of the multi-way valve with the cooler. Regardless of whether the corresponding circuit control mechanism in the hydraulic system is actuated, the oil of the multi-way valve can be directly delivered to the cooler through the working oil port for cooling, and the flow rate entering the cooler is relatively more stable. The flow rate of the oil entering the cooler in the hydraulic system is also relatively large, so that the circulation efficiency of the oil passing through the cooler is higher, thereby improving the cooling effect of the cooler on the oil in the hydraulic system.

[0004] In order to achieve the above-mentioned object, the present disclosure provides a hydraulic system in a first aspect, comprising:

[0005] Multi-way valve;

[0006] a first hydraulic pump, wherein an oil inlet of the first hydraulic pump is communicated with an oil tank, and an oil outlet of the first hydraulic pump is communicated with an oil inlet of the multi-way valve, so as to transport the oil in the oil tank into the multi-way valve;

[0007] A cooler, wherein the oil inlet of the cooler is connected to the working oil port of the multi-way valve, and the oil outlet of the cooler is connected to the oil tank, so as to cool the oil flowing from the working oil port of the multi-way valve to the oil tank.

[0008] Optionally, the oil return port of the multi-way valve is communicated with the oil inlet of the cooler to cool the oil flowing from the oil return port of the multi-way valve to the oil tank.

[0009] Optionally, the multi-way valve includes an oil inlet and return connection, a cooling and outrigger control connection, and an arm connection; the oil inlet of the first hydraulic pump is connected to the oil tank, the oil outlet of the first hydraulic pump is connected to the oil inlet of the oil inlet and return connection, and the oil inlet of the cooler is connected to the working oil port of the cooling and outrigger control connection.

[0010] Optionally, the hydraulic system further comprises a pumping sub-hydraulic system, the return oil circuit of the pumping sub-hydraulic system being in communication with the oil inlet of the cooler for cooling the oil flowing from the pumping sub-hydraulic system to the oil tank.

[0011] Optionally, the pumping sub-hydraulic system includes a closed main pump assembly and a flushing valve, wherein the flushing valve is connected to the closed main pump assembly and the cooler respectively, and is used to transport the oil in the return oil circuit of the closed main pump assembly to the cooler for cooling.

[0012] Optionally, the pumping sub-hydraulic system includes a second main pump and a hydraulic main valve, the oil inlet of the second main pump is connected to the oil tank, the oil outlet of the second main pump is connected to the oil inlet of the hydraulic main valve, and the return oil port of the hydraulic main valve is connected to the cooler, which is used to transport the oil in the return oil circuit of the pumping sub-hydraulic system to the oil in the oil tank for cooling.

[0013] Optionally, the hydraulic system further comprises a stirrer hydraulic system, and an oil return circuit of the stirrer hydraulic system is connected to an oil inlet of the cooler.

[0014] Optionally, the multi-way valve is constructed as an electro-hydraulic proportional multi-way valve, and the hydraulic system also includes a controller and a temperature sensor. The temperature sensor is arranged in the oil tank for detecting the temperature of the oil in the oil tank. The controller is communicatively connected with the temperature sensor and the electro-hydraulic proportional multi-way valve, respectively. The controller is used to control the electro-hydraulic proportional multi-way valve according to the oil temperature in the oil tank to allow the oil in the electro-hydraulic proportional multi-way valve to enter the cooler through the working oil port of the electro-hydraulic proportional multi-way valve.

[0015] Optionally, the cooler includes a cooling fan, and the controller is communicatively connected to the cooling fan for controlling the operation of the cooling fan.

[0016] A second aspect of the present disclosure provides an engineering machine, comprising the above-mentioned hydraulic system.

[0017] Through the above technical scheme, the hydraulic system includes a multi-way valve, a first hydraulic pump and a cooler. The oil inlet of the first hydraulic pump is connected to the oil tank, and the oil outlet of the first hydraulic pump is connected to the oil inlet of the multi-way valve to transport the oil in the oil tank into the multi-way valve. The oil inlet of the cooler is connected to the working oil port of the multi-way valve, and the oil outlet of the cooler is connected to the oil tank to cool the oil flowing from the working oil port of the multi-way valve to the oil tank. The oil inlet of the cooler is connected to the working oil port of the multi-way valve. Regardless of whether the corresponding circuit control mechanism in the hydraulic system is actuated or not, the oil transported into the multi-way valve by the first hydraulic pump can directly enter the cooler through the working oil port of the multi-way valve connected to the cooler. The flow rate entering the cooler is relatively more stable, and the flow rate of the oil entering the cooler in the hydraulic system is also large, so that the circulation efficiency of the oil passing through the cooler is high, thereby improving the cooling effect of the cooler on the oil in the hydraulic system.

[0018] Other features and advantages of the present disclosure will be described in detail in the following detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present disclosure but do not constitute a limitation of the present disclosure. In the accompanying drawings:

[0020] Figure 1 is a schematic diagram of a hydraulic system when the pumping sub-hydraulic system provided in an exemplary embodiment of the present disclosure is a closed pump system;

[0021] Figure 2 2 is a schematic diagram of a hydraulic system when the pumping sub-hydraulic system provided in an exemplary embodiment of the present disclosure is an open pump system.

[0022] Description of Reference Numerals

[0023] 10-oil tank; 20-pumping sub-hydraulic system; 21-closed main pump assembly; 211-first main pump; 22-main oil cylinder; 23-flushing valve; 24-hydraulic main valve; 25-second main pump; 30-cooler; 40-first hydraulic pump; 50-outrigger multi-way valve; 60-multi-way valve; 61-inlet and return oil connection; 62-cooling and outrigger control connection; 63-arm connection; 70-controller; 80-temperature sensor; 90-agitation sub-hydraulic system. DETAILED DESCRIPTION

[0024] The specific implementation of the present disclosure is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the present disclosure, and is not used to limit the present disclosure.

[0025] In the present disclosure, unless otherwise stated, directional words such as "inside" and "outside" refer to the inside and outside of the outline of a component or structure itself. "First" and "second" are used to distinguish one element from another element and do not have order or importance. In addition, in the description with reference to the drawings, the same mark in different drawings represents the same element.

[0026] In the related art, during the operation of a concrete pump truck, heat is generated in its hydraulic system, causing the temperature of the oil in the hydraulic system to rise. Therefore, it is necessary to cool down the hotter oil in the hydraulic system. Usually, a cooler is set in the hydraulic system of a concrete pump truck, and the return oil circuits of each subsystem of the pump truck hydraulic system are connected to the cooler. The cooler cools the oil in the return oil circuit and cools down the oil in the return oil circuit of the hydraulic system. However, the amount of oil flowing into the cooler from the return oil circuit of each sub-hydraulic system is affected by the action of the mechanism of the concrete pump truck controlled by the sub-hydraulic system. When the mechanism controlled by the hydraulic subsystem is in action, the amount of oil flowing into the cooler from the return oil circuit of the hydraulic subsystem is larger. When the mechanism controlled by the hydraulic subsystem is not in action, the amount of oil flowing into the cooler from the return oil circuit of the hydraulic subsystem is relatively small, even close to zero, resulting in large fluctuations in the amount of oil flowing into the cooler from each hydraulic subsystem, and low circulation efficiency of the oil passing through the cooler, which makes the cooling efficiency of the cooler on the oil in the hydraulic system low, and will make the temperature of the oil in the oil tank higher, reducing the working efficiency of the hydraulic system.

[0027] like Figure 1 to Figure 2As shown, in view of the above technical problems, the first aspect of the present disclosure provides a hydraulic system, including a multi-way valve 60, a first hydraulic pump 40 and a cooler 30, wherein the oil inlet of the first hydraulic pump 40 is connected to the oil tank 10, the oil outlet of the first hydraulic pump 40 is connected to the oil inlet of the multi-way valve 60, and the oil in the oil tank 10 is transported into the multi-way valve 60 through the first hydraulic pump 40. The working oil port of the multi-way valve 60 is connected to the oil inlet of the cooler 30, and the oil outlet of the cooler 30 is connected to the oil tank 10, so as to cool the oil flowing from the working oil port of the multi-way valve 60 to the oil tank 10. The oil in the oil tank 10 enters the multi-way valve 60 through the first hydraulic pump 40, and the oil entering the multi-way valve 60 enters the cooler 30 through the working oil port of the multi-way valve 60, and the cooled oil returns to the oil tank 10, forming a first cooling circulation loop for cooling the oil in the oil tank 10. Furthermore, the oil delivered by the first hydraulic pump 40 to the multi-way valve 60 can be directly delivered to the cooler 30 through the working oil port of the multi-way valve 60 for cooling, and is not affected by whether the mechanism controlled by the multi-way valve 60 is in operation. This makes the flow rate of the oil delivered to the cooler 30 from the working oil port of the multi-way valve 60 larger and more stable, thereby making the circulation efficiency of the oil passing through the cooler 30 in the first cooling circulation loop higher, improving the cooling efficiency of the cooler 30 on the oil in the hydraulic system, and correspondingly reducing the temperature of the oil in the oil tank 10, thereby avoiding the influence of the high temperature of the oil in the oil tank 10 on the working efficiency of the hydraulic system.

[0028] In the above-mentioned embodiment, the cooler 30 is an oil cooling device, which may have other names, such as an oil cooler, a radiator, etc.

[0029] like Figure 1 or Figure 2 As shown, the multi-way valve 60 includes an oil inlet and return link 61, a cooling and outrigger control link 62, and a boom link 63. The oil inlet and return link 61 has a total oil inlet P of the multi-way valve 60 and a total oil return R of the multi-way valve 60; the boom link 63 has two working oil ports A2 and B2, which are connected to the execution circuit for controlling the action of the boom; the cooling and outrigger control link 62 has two working oil ports A1 and B1, one of which A1 is connected to the outrigger multi-way valve 50, and the other B1 is connected to the oil inlet of the cooler 30. In addition, the oil inlet of the first hydraulic pump 40 is connected to the oil tank 10, and the oil outlet of the first hydraulic pump 40 is connected to the total oil inlet P of the multi-way valve 60 on the oil inlet and return link 61. The first hydraulic pump 40 delivers the oil in the oil tank 10 into the multi-way valve 60 through the main oil inlet P of the multi-way valve 60. The oil entering the multi-way valve 60 can enter the cooler 30 through the working oil port B1 of the cooling and outrigger control link 62. The oil is cooled by the cooler 30 and then flows back to the oil tank 10.

[0030] It should be understood that the position of the working oil port on the multi-way valve 60 connected to the cooler 30 can be arbitrarily set according to actual needs. For example, the idle working oil ports of other links on the multi-way valve 60 can be connected to the cooler 30, or a single working link can be used as a cooling link, and the working oil port connected to the cooler 30 can be set on the cooling link, which is not limited here.

[0031] In the above embodiment, the oil return port of the multi-way valve 60 can be connected to the oil inlet of the cooler 30, so that the oil in the oil return passage of the multi-way valve 60 can be cooled by the cooler 30 and then returned to the oil tank 10. For example, when the boom of the concrete pump truck is rotating or extending, the oil in the oil return passage of the multi-way valve 60 will be transported to the cooler 30 for cooling.

[0032] In some embodiments, when the concrete pump truck adopts a load-sensitive variable pump system, the first hydraulic pump 40 can be a variable pump, and the inlet and return oil connection 61 of the multi-way valve 60 has a feedback oil port LS connected to the variable pump displacement control circuit. The variable pump displacement control circuit for adjusting the displacement of the first hydraulic pump 40 constructed as a variable pump is connected to the multi-way valve 60 through the feedback oil port, so that the variable pump displacement control circuit can adjust the displacement of the first hydraulic pump 40 constructed as a variable pump according to the load of the system.

[0033] In some embodiments, the multi-way valve 60 is configured as an electro-hydraulic proportional multi-way valve 60, and the hydraulic system further includes a controller 70 and a temperature sensor 80. The temperature sensor 80 is disposed in the oil tank 10 and is used to detect the temperature of the oil in the oil tank 10. The controller 70 is respectively connected to the temperature sensor 80 and the electro-hydraulic proportional multi-way valve 60 for communication. The temperature sensor 80 detects the temperature in the oil tank 10, and then transmits the temperature information to the controller 70. The controller 70 controls the electro-hydraulic proportional multi-way valve 60 to operate according to the temperature information of the temperature sensor 80, so that the oil delivered into the electro-hydraulic proportional multi-way valve 60 by the first hydraulic pump 40 can enter the cooler 30 through the working oil port of the electro-hydraulic proportional multi-way valve 60.

[0034] Specifically, Figure 1 or Figure 2As shown, the temperature sensor 80 can measure the oil temperature in the oil tank 10 and feed back the oil temperature information to the controller 70. The controller 70 controls the valve body in the cooling and leg control link 62 in the electro-hydraulic proportional multi-way valve 60 according to the oil temperature information transmitted by the temperature sensor 80. For example, when the temperature sensor 80 detects that the oil temperature in the oil tank 10 rises to a preset opening oil temperature value, the controller 70 controls the valve body switching position in the cooling and outrigger control link 62 of the electro-hydraulic proportional multi-way valve 60, so that the valve body is in the upper position, and the oil inlet of the valve body is connected to the working oil port B1 of the cooling and outrigger control link 62, so that the oil delivered into the electro-hydraulic proportional multi-way valve 60 by the first hydraulic pump 40 can enter the cooler 30 for cooling through the working oil port B1 of the cooling and outrigger control link 62; when the temperature sensor 80 detects that the temperature in the oil tank 10 drops to a preset closing temperature, the controller 70 controls the valve body switching position of the cooling and outrigger control link 62 in the electro-hydraulic proportional multi-way valve 60, stops supplying oil to the cooler 30 through the working oil port B1 of the cooling and outrigger control link 62, and realizes automatic control of the oil entering the cooler 30 for cooling through the working oil port B1 of the cooling and outrigger control link 62. In addition, the controller 70 can also control the valve body switching position of the cooling and outrigger control link 62 in the electro-hydraulic proportional multi-way valve 60 according to the oil temperature detected in real time by the temperature sensor 80, so as to control the on-off connection between the oil inlet of the valve body of the cooling and outrigger control link 62 and the working oil port B1 of the cooling and outrigger control link 62, so as to stabilize the oil temperature in the oil tank 10 within a preset range.

[0035] In addition, a remote controller may be provided, and the remote controller sends instructions to the controller 70, so that the controller 70 controls the electro-hydraulic proportional multi-way valve 60, controls the valve body of the cooling and outrigger control link 62 to switch the working position, so that the oil delivered by the first hydraulic pump 40 into the electro-hydraulic proportional multi-way valve 60 can enter the cooler 30 through the working oil port B1 of the cooling and outrigger control link 62 for cooling. And the valve port opening of the valve body of the cooling and outrigger control link 62 can be controlled to achieve the size of the flow delivered to the working oil port B1 through the valve body of the cooling and outrigger control link 62. The opening of the valve body oil inlet of the cooling and outrigger control link 62 in the electro-hydraulic proportional multi-way valve 60 is controllable, so that the oil flow output for cooling can be controlled, so as to reduce the influence of the diversion on the boom movement.

[0036] It should be understood that the cooler includes a cooling fan, and the controller 70 can be connected to the cooling fan of the cooler 30 to control the operation of the cooling fan. For example, the controller can control the start and stop of the cooling fan and the speed of the cooling fan when it rotates.

[0037] In the above-mentioned embodiment, the controller 70 can control both the electro-hydraulic proportional multi-way valve 60 and the fan of the cooler 30, so as to make the oil cooling control in the system more flexible.

[0038] like Figure 1 and Figure 2 As shown, in some embodiments, the hydraulic system further includes a pumping sub-hydraulic system 20, and an oil return circuit of the pumping sub-hydraulic system 20 is connected to an oil inlet of a cooler 30 for cooling the oil flowing from the pumping sub-hydraulic system 20 to the oil tank 10.

[0039] In one application scenario, such as Figure 1 As shown, the pumping sub-hydraulic system 20 is a closed pumping hydraulic system, which includes a closed main pump assembly 21 and a flushing valve 23. The oil inlet of the flushing valve 23 is connected to the closed main pump assembly 21, and the oil outlet of the flushing valve 23 is connected to the cooler 30, which is used to transport the oil in the return oil circuit of the closed main pump assembly 21 to the cooler 30 for cooling.

[0040] For ease of understanding, the working principle of the flushing valve 23 is briefly described. The flushing valve 23 is connected to the closed main pump assembly 21. There is a pressure difference between the two oil ports of the first main pump 211 in the closed main pump assembly 21, so that the circuit in the closed main pump assembly 21 connected to the first main pump 211 forms a high-pressure side and a low-pressure side. The oil on the high-pressure side of the closed main pump assembly 21 pushes the valve core of the flushing valve 23 to move and open, so as to transport the oil on the low-pressure side to the cooler 30 through the flushing valve 23 for cooling. When the first main pump 211 in the closed main pump assembly 21 stops working, the flushing valve 23 is closed, and the closed main pump assembly 21 stops transporting oil to the cooling zone through the flushing valve 23.

[0041] In addition, the pumping sub-hydraulic system 20 also includes a main actuator, and the closed main pump assembly 21 is connected to the main actuator to drive the main actuator to operate. According to different engineering machinery, the closed main pump assembly 21 can drive different main actuators. For example, when the hydraulic system is a hydraulic system of a concrete pump truck, the main actuator is a main oil cylinder 22. The closed main pump assembly 21 is connected to the main oil cylinder 22, and the closed main pump assembly 21 drives the main oil cylinder 22 to operate.

[0042] In another application scenario, such as Figure 2 As shown, the pumping sub-hydraulic system 20 is an open pumping hydraulic system. The pumping sub-hydraulic system 20 includes a second main pump 25 and a hydraulic main valve 24, the oil inlet of the second main pump 25 is connected to the oil tank 10, the oil outlet of the second main pump 25 is connected to the oil inlet of the hydraulic main valve 24, and the oil return port of the hydraulic main valve 24 is connected to the cooler 30, which is used to transport the oil in the oil return oil circuit of the pumping sub-hydraulic system 20 to the oil in the oil tank 10 for cooling.

[0043] In some embodiments, the hydraulic system further includes a stirrer hydraulic system 90, the return oil circuit of the stirrer hydraulic system 90 is connected to the oil inlet of the cooler 30, so that the oil in the return oil circuit of the stirrer hydraulic system 90 can be passed into the cooler 30 for cooling. The stirrer hydraulic system 90 is used to control the stirring mechanism of the concrete pump truck to stir the concrete.

[0044] In some embodiments, a one-way valve may be selectively provided on each oil circuit connected to the oil inlet of the cooler 30 according to actual conditions to prevent the oil in different oil circuits from flowing back. For example, a one-way valve may be provided on the oil circuit connected between the return oil circuit of the pumping sub-hydraulic system 20 and the oil inlet of the cooler 30, the oil circuit connected between the total return oil port R of the multi-way valve 60 and the oil inlet of the cooler 30, the oil circuit connected between the working oil port B1 of the cooling and outrigger working connection in the multi-way valve 60 and the oil inlet of the cooler 30, and the oil circuit connected between the stirring sub-hydraulic system 90 and the oil inlet of the cooler 30. It should be understood that when the matching degree between the oil circuits connected to the cooler 30 is high and the oil in each oil circuit does not affect the flow of the oil to the inlet of the cooler 30, a one-way valve may not be provided.

[0045] In addition, according to actual needs, the cooler 30 can adopt a cooler 30 with a bypass valve, and a return oil filter can be added between the cooler 30 and the hydraulic oil tank 10, which will not be repeated here.

[0046] The second aspect of the present disclosure provides an engineering machine, comprising the above hydraulic system. The engineering machine has all the beneficial effects of the above hydraulic system.

[0047] In some embodiments, the engineering machinery may be configured as a wet spraying machine or a fire truck in addition to being configured as a concrete pump truck, which will not be described in detail here.

[0048] The preferred embodiments of the present disclosure are described in detail above in conjunction with the accompanying drawings; however, the present disclosure is not limited to the specific details in the above embodiments. Within the technical concept of the present disclosure, a variety of simple modifications can be made to the technical solution of the present disclosure, and these simple modifications all fall within the protection scope of the present disclosure.

[0049] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present disclosure will not further describe various possible combinations.

[0050] In addition, various embodiments of the present disclosure may be arbitrarily combined, and as long as they do not violate the concept of the present disclosure, they should also be regarded as the contents disclosed by the present disclosure.

Claims

1. A hydraulic system, characterized in that: include: Multi-way valve; a first hydraulic pump, wherein an oil inlet of the first hydraulic pump is communicated with an oil tank, and an oil outlet of the first hydraulic pump is communicated with an oil inlet of the multi-way valve, so as to transport the oil in the oil tank into the multi-way valve; A cooler, wherein the oil inlet of the cooler is connected to the working oil port of the multi-way valve, and the oil outlet of the cooler is connected to the oil tank, so as to cool the oil flowing from the working oil port of the multi-way valve to the oil tank.

2. The hydraulic system according to claim 1, characterized in that: The oil return port of the multi-way valve is communicated with the oil inlet of the cooler so as to cool the oil flowing from the oil return port of the multi-way valve to the oil tank.

3. The hydraulic system according to claim 1, characterized in that: The multi-way valve includes an oil inlet and return connection, a cooling and outrigger control connection, and an arm connection. The oil inlet of the first hydraulic pump is connected to the oil tank, the oil outlet of the first hydraulic pump is connected to the oil inlet of the oil inlet and return connection, and the oil inlet of the cooler is connected to the working oil port of the cooling and outrigger control connection.

4. The hydraulic system according to any one of claims 1 to 3, characterized in that: The hydraulic system further comprises a pumping sub-hydraulic system, wherein an oil return circuit of the pumping sub-hydraulic system is in communication with an oil inlet of the cooler so as to cool the oil flowing from the pumping sub-hydraulic system to the oil tank.

5. The hydraulic system according to claim 4, characterized in that: The pumping sub-hydraulic system includes a closed main pump assembly and a flushing valve, wherein the flushing valve is respectively connected to the closed main pump assembly and the cooler, and is used to transport the oil in the return oil circuit of the closed main pump assembly to the cooler for cooling.

6. The hydraulic system according to claim 4, characterized in that: The pumping sub-hydraulic system includes a second main pump and a hydraulic main valve. The oil inlet of the second main pump is connected to the oil tank, the oil outlet of the second main pump is connected to the oil inlet of the hydraulic main valve, and the oil return port of the hydraulic main valve is connected to the cooler, which is used to transport the oil in the return oil circuit of the pumping sub-hydraulic system to the oil in the oil tank for cooling.

7. The hydraulic system according to claim 1, characterized in that: The hydraulic system further comprises a stirrer hydraulic system, and an oil return oil circuit of the stirrer hydraulic system is communicated with an oil inlet of the cooler.

8. The hydraulic system according to claim 1, characterized in that: The multi-way valve is constructed as an electro-hydraulic proportional multi-way valve. The hydraulic system also includes a controller and a temperature sensor. The temperature sensor is used to detect the oil temperature in the oil tank. The controller is communicated with the temperature sensor and the electro-hydraulic proportional multi-way valve respectively. The controller is used to control the electro-hydraulic proportional multi-way valve according to the oil temperature in the oil tank to allow the oil in the electro-hydraulic proportional multi-way valve to enter the cooler through the working oil port of the electro-hydraulic proportional multi-way valve.

9. The hydraulic system according to claim 8, characterized in that: The cooler includes a cooling fan; the controller is in communication connection with the cooling fan and is used to control the operation of the cooling fan.

10. An engineering machine, characterized in that: Comprising a hydraulic system as claimed in any one of claims 1 to 9.

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