Hydraulic systems and construction machinery

Abstract

This invention provides a hydraulic system and engineering machinery. The hydraulic system includes an oil tank, a control valve assembly, and an auxiliary return oil device. The control valve assembly is adapted to control the movement of an actuator and includes a first return oil port and a first replenishment oil port. The first return oil port is connected to the oil tank via a first pipeline, and the first replenishment oil port is adapted to be connected to the actuator. The auxiliary return oil device has its outlet connected to the oil tank via a second pipeline, and its inlet connected to the actuator. When the return oil pressure of the hydraulic system is too high, one path of return oil flows back to the oil tank via the first pipeline, and the other path flows through the actuator and then back to the oil tank via the auxiliary return oil device, thereby reducing the peak return oil pressure of the hydraulic system. Therefore, the technical solution of this invention solves the defect in the prior art where excavators have difficulty reducing the peak return oil pressure.

Description

Technical Field

[0001] This invention relates to the field of hydraulic control technology, specifically to a hydraulic system and engineering machinery. Background Technology

[0002] With the improvement of my country's economic strength and the rapid growth of national construction needs, the demand for large hydraulic excavators is constantly increasing, and the configuration of attachments is becoming more diversified (such as buckets, rippers, and breakers). The working performance of each attachment varies significantly, placing higher demands on the excavator's hydraulic system. To ensure the excavator's adaptability, the return oil pressure of the hydraulic system is a crucial factor.

[0003] Traditional excavators use a return oil system with two main return ports and two auxiliary return ports in the control valve assembly. One main return port returns oil to the oil tank via a back pressure valve and radiator, while the other returns directly to the oil tank via a bypass valve. The auxiliary return ports replenish oil to the swing motor. Because only two main return ports with fixed diameters return oil to the system, when there is a sudden surge in return oil flow, the main return ports cannot reduce the peak return oil pressure. This instantaneous peak return oil pressure damages the radiator, affects the swing starting force, and also impacts digging force, while increasing fuel consumption. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the defect that excavators in the prior art have difficulty in reducing the peak return oil pressure, thereby providing a hydraulic system and engineering machinery.

[0005] To address the aforementioned problems, the present invention provides a hydraulic system comprising: an oil tank; a control valve assembly adapted to control the action of an actuator, the control valve assembly including a first return port and a first replenishment port, the first return port being connected to the oil tank via a first pipeline, and the first replenishment port being adapted to be connected to the actuator; and an auxiliary return device, the outlet of which is connected to the oil tank via a second pipeline, and the inlet of which is connected to the actuator.

[0006] Optionally, the auxiliary oil return device includes a first bypass valve, the outlet of which is connected to the oil tank via a second pipeline, and the valve body of the first bypass valve is provided with multiple inlets.

[0007] Optionally, the actuator includes a first actuator, the first actuator includes a second oil replenishment port, the first oil replenishment port is connected to the second oil replenishment port, and the inlet of the auxiliary oil return device is connected to the first oil replenishment port through a third pipeline.

[0008] Optionally, the first actuator is a rotary mechanism, and the second oil replenishment port of the rotary mechanism is connected to the first oil replenishment port through a fourth pipeline, and the third pipeline is connected to the fourth pipeline.

[0009] Optionally, the actuator includes a second actuator, which includes a second oil return port. The first oil return port is connected to the second oil return port, and the inlet of the auxiliary oil return device is connected to the first oil return port through a fifth pipeline.

[0010] Optionally, the second actuator is a hydraulic breaker, and the second return port of the hydraulic breaker is connected to the first pipeline through the sixth pipeline, and the fifth pipeline is connected to the sixth pipeline.

[0011] Optionally, a throttling valve may be installed on the third and / or fifth pipeline.

[0012] Optionally, a second bypass valve is provided on the first pipeline, the diameter of the third pipeline is less than or equal to the diameter of the first pipeline, and the model of the first bypass valve is less than or equal to the model of the second bypass valve.

[0013] Optionally, the hydraulic system further includes a temperature sensor and a control system, both of which are electrically connected to the control system; and / or, the hydraulic system further includes a pressure sensor and a control system, both of which are electrically connected to the control system.

[0014] The present invention also provides an engineering machine, including the above-described hydraulic system.

[0015] Optionally, the construction machinery is an excavator.

[0016] The present invention has the following advantages:

[0017] 1. Utilizing the technical solution of this invention, an auxiliary return oil device is installed within the hydraulic system. Therefore, when the return oil pressure of the hydraulic system is too high, one return oil path leads back to the oil tank via the first pipeline, while the other path passes through the actuator and returns to the oil tank via the auxiliary return oil device, thereby reducing the peak return oil pressure of the hydraulic system. Thus, the technical solution of this invention solves the defect in existing technologies where excavators struggle to reduce peak return oil pressure.

[0018] 2. When the return oil pressure of the hydraulic system is too high, one return oil path goes back to the oil tank from the first pipeline, and the other path goes back to the oil tank from the third pipeline through the auxiliary return oil device, thereby reducing the peak return oil pressure of the hydraulic system.

[0019] 3. The inlet of the auxiliary return oil device is connected to the first return oil port through the fifth pipeline. When the actuator is working and the return oil pressure is high (e.g., bucket, breaker, ripper), part of the return oil from the actuator can be returned to the oil tank through the fifth pipeline and the auxiliary return oil device, which can reduce the peak return oil pressure of the hydraulic system.

[0020] 4. When the temperature sensor detects a low temperature, the control system can increase the return oil flow of the throttle valve to ensure the hydraulic system has the minimum back pressure required for normal operation, thereby reducing energy consumption and improving work efficiency. When the temperature sensor detects a high temperature, the control system can decrease the return oil flow of the throttle valve to ensure sufficient hydraulic oil is available for cooling through the radiator.

[0021] 5. When the control system calculates that the probability of the peak return oil pressure exceeding the set value is relatively high, the control system can increase the return oil flow of the throttle valve and increase the total return oil diameter of the hydraulic system to the oil tank, thereby reducing the peak return oil pressure of the hydraulic system. When the control system calculates that the probability of the peak return oil pressure exceeding the set value is relatively low, the return oil flow of the throttle valve can be appropriately reduced. Attached Figure Description

[0022] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0023] Figure 1 A schematic diagram of the hydraulic control system of the present invention is shown.

[0024] Explanation of reference numerals in the attached figures:

[0025] 1. First pipeline; 2. Second pipeline; 3. Third pipeline; 4. Fourth pipeline; 5. Fifth pipeline; 6. Sixth pipeline; 10. Oil tank; 20. Control valve assembly; 21. First oil return port; 22. First oil replenishment port; 30. Actuator; 31. First actuator; 32. Second actuator; 301. Second oil return port; 302. Second oil replenishment port; 40. Auxiliary oil return device; 41. First bypass valve; 50. Throttle valve; 60. Temperature sensor; 70. Pressure sensor; 80. Back pressure valve; 90. Radiator; 100. Second bypass valve. Detailed Implementation

[0026] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0028] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0029] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0030] like Figure 1 As shown, the hydraulic system of the engineering machinery in this embodiment includes an oil tank 10, a control valve assembly 20, an actuator 30, and an auxiliary return oil device 40. The control valve assembly 20 is adapted to control the operation of the actuator 30. The control valve assembly 20 includes a first return oil port 21 and a first replenishment oil port 22. The first return oil port 21 is connected to the oil tank 10 via a first pipeline 1, and the first replenishment oil port is adapted to be connected to the actuator 30. The outlet of the auxiliary return oil device 40 is connected to the oil tank 10 via a second pipeline 2, and the inlet of the auxiliary return oil device 40 is connected to the actuator 30.

[0031] Using the technical solution of this embodiment, an auxiliary return oil device 40 is provided in the hydraulic system. Therefore, when the return oil pressure of the hydraulic system is too high, one return oil path goes from the first pipeline 1 back to the oil tank, and the other path passes through the actuator 30 and then returns to the oil tank 10 via the auxiliary return oil device 40, thereby reducing the peak return oil pressure of the hydraulic system. Therefore, the technical solution of this embodiment solves the defect in the prior art that excavators have difficulty in reducing the peak return oil pressure.

[0032] It should be noted that in this embodiment, the auxiliary oil return device 40 is connected to the actuator 30 in two ways. One way is that the actuator 30 includes a second oil replenishment port 302, and the first oil replenishment port 22 is connected to the second oil replenishment port 302. The inlet of the auxiliary oil return device 40 is connected to the first oil replenishment port through a third pipeline. The other way is that the actuator 30 includes a second oil return port 301, and the first oil return port 21 is connected to the second oil return port 301. The inlet of the auxiliary oil return device 40 is connected to the first oil return port 21 through a fifth pipeline 5.

[0033] When the return oil pressure of the hydraulic system is too high, one return oil path leads from the first pipeline 1 back to the oil tank 10, and the other path leads from the third pipeline 3 back to the oil tank via the auxiliary return oil device 40, thereby reducing the peak return oil pressure of the hydraulic system. Alternatively, the inlet of the auxiliary return oil device 40 is connected to the first return oil port 21 via the fifth pipeline 5. When the actuator 30 is working, causing a large return oil pressure (e.g., bucket, breaker, ripper), part of the return oil from the actuator 30 can return to the oil tank via the fifth pipeline 5 and the auxiliary return oil device 40, which can reduce the peak return oil pressure of the hydraulic system.

[0034] It should be noted that the actuator 30 can be a bucket (or a boom and stick connected to the bucket), a breaker, a ripper, etc. Furthermore, there can be one actuator 30 or multiple actuators 30.

[0035] Furthermore, the aforementioned control valve assembly 20 can control the movement of the actuator 30. Specifically, the hydraulic oil in the oil tank 10 can be pumped by a hydraulic pump and introduced into the control valve assembly 20 via an operating handle. The control valve assembly 20 is also provided with a working oil port (not shown in the figure), which is connected to the oil chamber corresponding to the actuator 30 via a pipeline. By switching the position of the valve core in the control valve assembly 20, the movement of the actuator 30 can be controlled (e.g., the extension or retraction of the hydraulic cylinder, the rotation of the hydraulic motor, etc.). At the same time, the return oil of the hydraulic system can flow back to the oil tank from the first return oil port 21 through the first pipeline 1.

[0036] Furthermore, in this embodiment, the first return port 21 is also the main return port of the control valve assembly 20. One function of the first replenishment port 22 of the control valve assembly 20 is to connect to the replenishment port of the actuator 30 to prevent the actuator 30 from drawing vacuum into its oil chamber during operation. Simultaneously, since the inlet of the auxiliary return device 40 is connected to the first replenishment port 22 via the third pipeline 3, the first replenishment port 22 also has a return function. When the return pressure of the hydraulic system is high, a portion of the return oil can return through the third pipeline 3 and the auxiliary return device 40, thereby reducing the peak return pressure of the hydraulic system.

[0037] Furthermore, regarding the configuration of the auxiliary oil return device 40 in this embodiment, it can be configured such that the auxiliary oil return device 40 is connected to the first oil replenishment port 22 only through the third pipeline 3, or it can be connected to the second oil return port 301 of the actuator 30 only through the fifth pipeline 5. Alternatively, the auxiliary oil return device 40 can employ both of the above configuration methods simultaneously.

[0038] like Figure 1 As shown, in this embodiment, the auxiliary return oil device 40 includes a first bypass valve 41, and the valve body of the first bypass valve 41 is provided with multiple inlets. Specifically, the first bypass valve 41 includes a valve body and a valve core disposed within the valve body. The valve core is in the form of a one-way valve, allowing hydraulic oil to flow unidirectionally in the direction from the hydraulic oil tank 10. When the pressure of the hydraulic oil is greater than a preset value (set pressure), the valve core is opened, and the hydraulic oil can pass through the first bypass valve 41, thereby flowing back to the oil tank.

[0039] Combination Figure 1 As can be seen, the valve body of the first bypass valve 41 has multiple inlets. Specifically, in this embodiment, the valve body has three inlets to meet various assembly requirements of the first bypass valve 41. The third pipeline 3 is connected to one of the inlets, and the fifth pipeline 5 is connected to another one of the inlets. All the inlets are connected to the valve core of the first bypass valve 41. In addition, if the hydraulic system has more actuators 30, the return ports of the remaining actuators 30 can be connected to the third inlet on the valve body of the first bypass valve 41 through pipelines.

[0040] In some embodiments not shown, the valve body may have one, two, four, or more inlets. The specific number on the valve body can be adjusted by those skilled in the art based on the number of actuators 30 in the hydraulic system.

[0041] like Figure 1 As shown, in this embodiment, the actuator 30 includes a first actuator 31, which can be a rotary mechanism (e.g., a rotary motor). The second oil supply port 302 of the rotary mechanism is connected to the first oil supply port 22 via a fourth pipe 4, and the third pipe 3 is connected to the fourth pipe 4. Specifically, the oil inlet of the rotary mechanism is connected to the working oil port of the control valve group 20 (not shown in the figure). The rotary mechanism is provided with a second oil supply port 302, which allows oil to be supplied to the oil chamber of the rotary mechanism, thereby preventing vacuum from occurring during the rotation of the rotary mechanism.

[0042] Specifically, during braking, the rotary motor may over-rotate due to inertia, which can cause a vacuum to be drawn into the oil chamber. Hydraulic oil can flow into the oil chamber of the rotary mechanism through the first oil replenishment port 22 and the second oil replenishment port 302, thereby achieving the effect of replenishing oil.

[0043] Combination Figure 1 As can be seen, the first oil replenishment port 22 and the second oil replenishment port 302 are connected through the fourth pipeline 4, so the hydraulic oil of the control valve assembly 20 can enter the rotary mechanism through the first oil replenishment port 22 and the second oil replenishment port 302. Furthermore, the third pipeline 3 and the fourth pipeline 4 are connected, thus allowing the inlet of the auxiliary oil return device 40 to connect with the first oil replenishment port 22. This connection method increases the total return oil diameter of the hydraulic system to the oil tank, thereby reducing the peak return oil pressure of the hydraulic system.

[0044] Preferably, the third pipe 3 and the fourth pipe 4 can be connected by a tee connector. Of course, the third pipe 3 and the fourth pipe 4 can also be connected by other methods.

[0045] like Figure 1 As shown, in this embodiment, the actuator 30 includes a second actuator 32, which can be a hydraulic breaker (or other attachments, such as hydraulic shears). The second return port 301 of the hydraulic breaker is connected to the first pipeline 1 via the sixth pipeline 6, and the fifth pipeline 5 is connected to the sixth pipeline 6. Specifically, when the hydraulic breaker is working, the return oil pressure is relatively high, so the return oil from its second return port 301 is divided into two paths. One path of return oil returns to the oil tank via the sixth pipeline 6 and the first pipeline 1, while the second path of return oil returns to the oil tank via the sixth pipeline 6 and the fifth pipeline 5 through the auxiliary return oil device 40. The above connection method can increase the total return oil diameter of the hydraulic system returning to the oil tank, thereby reducing the peak return oil pressure of the hydraulic system.

[0046] Preferably, the fifth pipe 5 and the sixth pipe 6 can be connected by a tee connector.

[0047] Of course, the first actuator 31 and the second actuator 32 mentioned above are not limited to rotary mechanisms and breakers. When the actuator 30 is another mechanism, the inlet of the auxiliary oil return device 40 can be connected to the oil return port or oil replenishment port of the structure.

[0048] Furthermore, as mentioned above, since the first bypass valve 41 has multiple inlets, when more actuators 30 are installed on the construction machinery, the return ports of each actuator 30 can be connected to the inlets of the first bypass valve 41 through pipelines, thereby facilitating the modification of the construction machinery.

[0049] like Figure 1As shown, in this embodiment, a throttle valve 50 is provided on the third pipeline 3 and / or the fifth pipeline 5. Specifically, in this embodiment, a throttle valve 50 is provided on both the third pipeline 3 and the fifth pipeline 5. The throttle valve 50 can adjust the return oil flow rate through the third pipeline 3 and the fifth pipeline 5, thereby adjusting the return oil volume through the auxiliary return oil device 40.

[0050] Of course, a throttle valve 50 may be installed only on the third pipe 3, or only on the fifth pipe 5.

[0051] Preferably, the throttle valve 50 is an adjustable flow valve.

[0052] like Figure 1 As shown, in the technical solution of this embodiment, the hydraulic system also includes a temperature sensor 60 and a control system. The temperature sensor 60 is adapted to detect the temperature of the hydraulic oil in the oil tank 10. Both the temperature sensor 60 and the throttle valve 50 are electrically connected to the control system.

[0053] Specifically, the temperature sensor 60 can be installed in the oil tank 10, enabling it to detect the temperature of the hydraulic oil within the tank. The control system can then control the opening degree of the throttle valve 50 based on the hydraulic oil temperature. Alternatively, the temperature sensor 60 can be installed at other locations within the hydraulic system, as long as it can detect the hydraulic oil temperature.

[0054] Specifically, when the temperature detected by temperature sensor 60 is low, the control system can increase the return oil flow of throttle valve 50 to ensure that the hydraulic system has the minimum back pressure required for normal operation, thereby reducing the energy consumption of the construction machinery and improving work efficiency. When the temperature detected by temperature sensor 60 is high, the control system can decrease the return oil flow of throttle valve 50 to ensure that sufficient hydraulic oil is available for cooling through the radiator.

[0055] like Figure 1 As shown, in this embodiment, the hydraulic system further includes a pressure sensor 70 and a control system. The pressure sensor 70 is adapted to detect the return oil pressure of the hydraulic system. Both the pressure sensor 70 and the throttle valve 50 are electrically connected to the control system. Specifically, there are two pressure sensors 70, one of which is installed on the first pipeline 1, and the other is installed on the sixth pipeline 6. Of course, the pressure sensors 70 can also be installed at other locations in the hydraulic system, as long as they can detect the return oil pressure.

[0056] The control system can control the opening degree of the throttle valve 50 according to the return oil pressure of the hydraulic system.

[0057] Specifically, the control system can calculate the peak return oil pressure of the hydraulic system using pressure sensor 70. Furthermore, the control system can calculate the probability that the peak return oil pressure exceeds a set value (e.g., 10 bar) during operation, thereby determining whether the system's return oil pressure affects the normal operation of the construction machinery.

[0058] When the control system calculates that the probability of the peak return oil pressure exceeding the set value is relatively high, the control system can increase the return oil flow of the throttle valve 50 and increase the total return oil flow diameter of the hydraulic oil returning to the oil tank, thereby reducing the peak return oil pressure of the hydraulic system. When the control system calculates that the probability of the peak return oil pressure exceeding the set value is relatively low, the return oil flow of the throttle valve 50 can be appropriately reduced.

[0059] like Figure 1 As shown, in the technical solution of this embodiment, there are two first oil return ports 21 and two first pipelines 1. One of the first pipelines 1 is equipped with a back pressure valve 80 and a radiator 90, and the other first pipeline 1 is equipped with a second bypass valve 100.

[0060] Specifically, the back pressure valve 80, the first bypass valve 41, and the second bypass valve 100 operate on the same principle, but their names differ depending on their function and location. Figure 1 A back pressure valve 80 and a radiator 90 are installed on the outer first pipeline 1. The back pressure valve 80 generates a certain back pressure in the first pipeline 1, which can provide some compensation from the return oil when the construction machinery is operating at low pressure and large amplitude. At the same time, the temperature of the return oil decreases after flowing through the radiator 90. Figure 1 A second bypass valve 100 is installed on the first pipeline 1 located in the middle, which is mainly used to adjust the lateral flow of the return oil back pressure. When the return oil volume and return oil pressure are greater than the rated pressure, the first pipeline 1 can divert the flow.

[0061] Furthermore, the opening pressure of the back pressure valve 80 is set at approximately 2.5 bar, and the opening pressure of the second bypass valve 100 is set at approximately 4.5 bar.

[0062] Furthermore, the model of the first bypass valve 41 can be set to be the same as that of the second bypass valve 100, or slightly lower than the opening pressure of the second bypass valve 100. This is sufficient to ensure the minimum return pressure required for the normal operation of the hydraulic system.

[0063] Based on the above description, the working principle of the hydraulic system in this embodiment is as follows:

[0064] The hydraulic oil in the oil tank 10 can be pumped by a hydraulic pump and introduced into the control valve assembly 20 via an operating handle. The control valve assembly 20 is also provided with a working oil port (not shown in the figure), which is connected to the oil chambers corresponding to the slewing mechanism and the breaker hammer via pipelines. By switching the position of the valve core in the control valve assembly 20, the movement of the slewing mechanism and the breaker hammer can be controlled. At the same time, the return oil of the hydraulic system can flow back to the oil tank from the first return oil port 21 through the first pipeline 1.

[0065] When the temperature detected by temperature sensor 60 is low, the control system can increase the return oil flow of throttle valve 50 on the third line 3 and / or the sixth line 6, ensuring that the hydraulic system has the minimum back pressure required for normal operation, thereby reducing the energy consumption of the construction machinery and improving work efficiency. When the temperature detected by temperature sensor 60 is high, the control system can decrease the return oil flow of throttle valve 50 on the third line 3 and / or the sixth line 6, ensuring that sufficient hydraulic oil is available for cooling through the radiator.

[0066] When the control system calculates that the probability of the peak return oil pressure exceeding the set value is relatively high, the control system can increase the return oil flow of the throttle valve 50 on the third pipeline 3 and / or the sixth pipeline 6, and increase the total return oil diameter of the hydraulic oil returning to the oil tank, thereby reducing the peak return oil pressure of the hydraulic system. When the control system calculates that the probability of the peak return oil pressure exceeding the set value is relatively low, the return oil flow of the throttle valve 50 on the third pipeline 3 and / or the sixth pipeline 6 can be appropriately reduced.

[0067] The present invention also provides an engineering machine, including the aforementioned hydraulic system. Preferably, the engineering machine is an excavator, a hydraulic breaker, or a ripper.

[0068] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A hydraulic system characterized by, include: tank; A control valve assembly is adapted to control the action of an actuator. The control valve assembly includes a working oil port, a first return oil port, and a first replenishment oil port. The first return oil port is connected to the oil tank through a first pipeline. The working oil port and the first replenishment oil port are adapted to be connected to the actuator. An auxiliary oil return device is provided, wherein the outlet of the auxiliary oil return device is connected to the oil tank via a second pipeline, and the inlet of the auxiliary oil return device is connected to the actuator. The auxiliary oil return device includes a first bypass valve, and the outlet of the first bypass valve is connected to the oil tank through the second pipeline; There are two first return ports and two first pipelines. One of the first pipelines is equipped with a back pressure valve and a radiator, and the other first pipeline is equipped with a second bypass valve. The opening pressure of the first bypass valve is less than or equal to the opening pressure of the second bypass valve. The actuator includes a first actuator, which is a rotary mechanism. The first actuator includes a second oil replenishment port, which is connected to the first oil replenishment port through a fourth pipeline. The inlet of the auxiliary oil return device is connected to the first oil replenishment port through a third pipeline, and the third pipeline is connected to the fourth pipeline. A throttling valve is installed on the third pipeline; The hydraulic system also includes a pressure sensor and a control system, both of which are electrically connected to the control system. The control system is used to control the opening degree of the throttle valve according to the return oil pressure of the hydraulic system.

2. The hydraulic system of claim 1, wherein, The actuator includes a second actuator, which includes a second oil return port. The first oil return port is connected to the second oil return port, and the inlet of the auxiliary oil return device is connected to the first oil return port through a fifth pipeline.

3. The hydraulic system of claim 2, wherein, The second actuator is a hydraulic breaker, and the second return port of the hydraulic breaker is connected to the first pipeline through the sixth pipeline, and the fifth pipeline is connected to the sixth pipeline.

4. The hydraulic system of claim 2, wherein, A throttling valve is installed on the fifth pipeline.

5. The hydraulic system according to any one of claims 1 to 4, characterized in that, The first bypass valve has multiple inlets on its valve body.

6. The hydraulic system according to claim 4, characterized in that, The hydraulic system also includes a temperature sensor, which is electrically connected to the control system.

7. An engineering machinery, characterized in that, Includes the hydraulic system as described in any one of claims 1 to 6.

8. The engineering machinery according to claim 7, characterized in that, The construction machinery mentioned is an excavator.

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