A hydraulic system for large-tonnage towing winch

Abstract

The present invention relates to a hydraulic system for a large-tonnage towing winch. The hydraulic system comprises an internal combustion engine, a closed hydraulic pump, an open hydraulic pump, a hydraulic motor, a filter, a cooler, a first check valve, and system piping accessories. The hydraulic system can switch between active cable-reeling, active cable-releasing, and passive cable-releasing modes. The present invention provides a hydraulic system for a large-tonnage towing winch that can implement active cable-reeling, active cable-releasing, and passive cable-releasing operations, ensuring thermal balance in the hydraulic system and achieving stable and long-term system operation.

Description

Technical Field

[0001] The present invention relates to the technical field of marine engineering equipment manufacturing, and in particular to a large-tonnage towing winch hydraulic system. Background Art

[0002] As deep-sea projects are implemented, offshore engineering equipment must also evolve towards larger, deep-water capabilities. Large-capacity towing winches are now widely used for long-distance towing of offshore platforms and deepwater anchoring. They are also frequently used for cable reeling and deploying during the construction of large offshore platforms. They are also used for anchoring and anchoring offshore floating wind turbines, making them a crucial auxiliary tool for marine energy development.

[0003] Located in the deep sea, with water depths ranging from hundreds to thousands of meters, the weight of the anchor chain increases with increasing water depth. During free-casting, the speed of the anchor chain must be able to support its weight to prevent accidents caused by unlimited acceleration due to gravity. Large-tonnage towing winches are critical equipment for the entire project. The harsh offshore operating environment and frequent, high-intensity operations necessitate extremely high reliability and safety requirements.

[0004] The main consideration of large-scale towing cranes is to achieve dynamic braking function under passive cable-releasing conditions. That is, during the cable-releasing process, it is necessary to ensure the cable-releasing speed and improve construction efficiency, while ensuring that there is sufficient impedance capacity to achieve dynamic balance under high-speed working conditions, and at the same time, it is also necessary to be able to digest the large amount of heat energy generated by the system due to passive work.

[0005] Because the system generates a large amount of heat energy, existing technologies often use low-pressure, high-flow hydraulic systems to ensure that the heat under negative work conditions can be carried away by the large-flow hydraulic oil and digested by the heat exchanger, ensuring the thermal balance of the system and achieving stable and long-term operation of the system.

[0006] Due to the supply problem of low-pressure and high-flow components, China is often subject to the control of foreign manufacturers. Therefore, developing a large-tonnage towing crane hydraulic system using a high-pressure oil system is a convenient way to solve the application bottleneck. Summary of the Invention

[0007] In view of the above problems in the prior art, the present invention proposes a hydraulic system for a large-tonnage towing winch, which can realize active cable collection, active cable release and passive cable release.

[0008] Specifically, the present invention provides a large-tonnage towing winch hydraulic system, comprising an internal combustion engine, a closed hydraulic pump, an open hydraulic pump, a hydraulic motor, a filter, a cooler, a first one-way valve, and system pipeline accessories. The large-tonnage towing winch hydraulic system can be switched between an active cable-reeling mode, an active cable-releasing mode, and a passive cable-releasing mode.

[0009] In the active cable reeling mode, the internal combustion engine drives the closed hydraulic pump to operate, and the working medium flows in the order of the closed hydraulic pump, the first one-way valve, the hydraulic motor, and then returns to the closed hydraulic pump, forming a first closed loop; at the same time, the internal combustion engine drives the open hydraulic pump to operate, and the working medium flows in the order of the open hydraulic pump, the filter, the cooler, and then returns to the open hydraulic pump, forming an open loop, and the open hydraulic pump replenishes the working medium to the first closed loop;

[0010] In the active cable-releasing operating mode, the internal combustion engine drives the closed hydraulic pump to operate, and the working medium flows in the following order: the closed hydraulic pump, the hydraulic motor, the first one-way valve, and then returns to the closed hydraulic pump, forming a second closed loop. Simultaneously, the internal combustion engine drives the open hydraulic pump to operate, and the working medium flows in the following order: the open hydraulic pump, the filter, the cooler, and then returns to the open hydraulic pump, forming an open loop. The open hydraulic pump replenishes the working medium to the second closed loop.

[0011] In the passive cable-releasing working mode, the passive power and active power of the system are compared. If the set conditions are met, the internal combustion engine drives the open hydraulic pump to operate, and the working medium flows in the order of the open hydraulic pump, the hydraulic motor, the filter, the cooler, and then back to the open hydraulic pump;

[0012] If the set conditions are not met, the working medium flows in the direction of the second closed loop, and the closed hydraulic pump inputs the received energy into the internal combustion engine; or the internal combustion engine drives the open hydraulic pump to operate, and the working medium flows in the direction of the open hydraulic pump, the hydraulic motor, the filter, the cooler, and then returns to the open hydraulic pump.

[0013] According to one embodiment of the present invention, the first one-way valve is a hydraulically controlled one-way valve.

[0014] According to one embodiment of the present invention, the large-tonnage towing winch hydraulic system further includes a first reversing valve, and the first reversing valve is used to control the flow direction of the first one-way valve to change the flow direction of the working medium.

[0015] According to one embodiment of the present invention, the large-tonnage towing winch hydraulic system further includes a second one-way valve. In the active retracting working mode, the open hydraulic pump replenishes the working medium to the first closed loop through the second one-way valve.

[0016] According to one embodiment of the present invention, the large-tonnage towing winch hydraulic system further includes a third one-way valve. In the active cable-releasing working mode, the open hydraulic pump replenishes the working medium to the second closed loop through the third one-way valve.

[0017] According to one embodiment of the present invention, the large-tonnage towing winch hydraulic system further includes a first relief valve;

[0018] In the active cable-reeling mode and the active cable-releasing mode, the internal combustion engine drives the open hydraulic pump to operate, and the working medium flows sequentially through the open hydraulic pump, the first relief valve, the filter, the cooler, and then back to the open hydraulic pump, forming the open loop.

[0019] According to one embodiment of the present invention, the large-tonnage towing winch hydraulic system further includes a second reversing valve for controlling the action of the first overflow valve.

[0020] According to one embodiment of the present invention, the large-tonnage towing winch hydraulic system further includes a second relief valve;

[0021] In the passive cable-releasing mode, the passive power and active power of the system are compared. If the set conditions are met, the internal combustion engine drives the open hydraulic pump to operate, and the working medium flows in the order of the open hydraulic pump, the hydraulic motor, the second relief valve, the filter, the cooler, and then back to the open hydraulic pump.

[0022] According to one embodiment of the present invention, the second relief valve is a safety relief valve or a proportional relief valve.

[0023] According to one embodiment of the present invention, the large-tonnage towing winch hydraulic system further includes an accumulator connected to the oil suction line of the open hydraulic pump.

[0024] The present invention provides a large-tonnage towing winch hydraulic system that can effectively switch between active cable-reeling working mode, active cable-releasing working mode and passive cable-releasing working mode, ensuring the thermal balance of the large-tonnage towing winch hydraulic system and achieving stable and long-term operation of the system.

[0025] It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings are included to provide a further understanding of the invention and are incorporated in and constitute a part of this application. The accompanying drawings illustrate embodiments of the invention and together with the description serve to explain the principle of the invention.

[0027] In the attached figure:

[0028] Figure 1 The figure shows a structural diagram of a hydraulic system of a large-tonnage towing winch according to an embodiment of the present invention.

[0029] The above drawings include the following reference numerals:

[0030] Large tonnage towing winch hydraulic system 100

[0031] Internal Combustion Engine 101

[0032] Closed hydraulic pump 102

[0033] Open hydraulic pump 103

[0034] Hydraulic motor 104

[0035] Filter 105

[0036] Cooler 106

[0037] First one-way valve 107

[0038] The first reversing valve 108

[0039] Second one-way valve 109

[0040] The third one-way valve 110

[0041] First relief valve 111

[0042] The second reversing valve 112

[0043] Second relief valve 113

[0044] Accumulator 114 DETAILED DESCRIPTION

[0045] It should be noted that, unless there is any conflict, the embodiments and features in the embodiments of this application can be combined with each other.

[0046] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, 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 application and its application or use. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0047] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0048] Unless otherwise specifically stated, the relative arrangement of the parts and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present application. 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 actual proportional relationships. 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 limitations. 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.

[0049] In the description of this application, it should be understood that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "horizontal, vertical, vertical, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of this application; the directional words "inside and outside" refer to the inside and outside relative to the outline of each component itself.

[0050] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used herein to describe the spatial positional relationship of a device or feature to other devices or features as shown in the figures. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figures. For example, if the device in the drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below other devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0051] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is solely for the purpose of distinguishing the corresponding components. Unless otherwise stated, these terms have no special meaning and therefore should not be construed as limiting the scope of protection of this application. Furthermore, while the terms used in this application are selected from commonly known and commonly used terms, some terms mentioned in this specification may have been selected by the applicant at his or her discretion, and their detailed meanings are explained in the relevant sections of this description. Furthermore, this application should be understood not only by the actual terms used, but also by the meaning implied by each term.

[0052] Figure 1 The following diagram illustrates the structure of a hydraulic system for a large-tonnage towing winch according to one embodiment of the present invention. As shown, the hydraulic system 100 primarily comprises an internal combustion engine 101, a closed-circuit hydraulic pump 102, an open-circuit hydraulic pump 103, a hydraulic motor 104, a filter 105, a cooler 106, a first check valve 107, and system piping components. The hydraulic system 100 can be switched between active cable-reeling, active cable-releasing, and passive cable-releasing modes.

[0053] The internal combustion engine 101 drives a series-connected pump system consisting of a closed hydraulic pump 102 and an open hydraulic pump 103. The closed hydraulic pump 102, first one-way valve 107, and hydraulic motor 104 form a closed system. The closed system performs positive or negative operation, providing power for cable reeling and overcoming the cable's gravity. It also uses dynamic braking to dissipate the work done by the anchor cable's gravity, which increases cable payout speed and load. The open hydraulic pump 103, filter 105, and cooler 106 form an open system. The open system performs negative operation, dissipating the work done by the anchor cable's gravity through dynamic braking. This combination enables controllable active cable reeling and passive cable payout. It should be noted that, by way of example and not limitation, the internal combustion engine 101 can be replaced with an electric motor to drive the closed hydraulic pump 102 and the open hydraulic pump 103.

[0054] in, It is used to indicate the circulation direction of the working medium. In the active cable-reeling working mode, the hydraulic motor 104 performs work and outputs kinetic energy to the cable drum to perform cable-reeling. This indicates the direction of the working medium's circulation. In the active cable-paying mode, the hydraulic motor 104 generates power, outputting kinetic energy to the cable drum to release the cable. In the passive cable-paying mode, the cable drum inputs kinetic energy to the hydraulic motor 104 to release the cable. ← indicates the direction of the working medium's circulation. In the passive cable-paying mode, the cable drum inputs kinetic energy to the hydraulic motor 104 to release the cable.

[0055] Specifically, in the active cable reeling mode, the internal combustion engine 101 drives the closed hydraulic pump 102. The working medium flows, as indicated by the arrows, through the closed hydraulic pump 102, the first one-way valve 107, the hydraulic motor 104, and then back to the closed hydraulic pump 102, forming a first closed loop. That is, the closed hydraulic pump 102 pumps the working medium (e.g., hydraulic oil) through the first one-way valve 107 and into the hydraulic motor 104. The pressure differential between the inlet and outlet ports of the hydraulic motor 104 drives the cable reel, completing the reeling operation. The working medium returns to the closed hydraulic pump 102 through the hydraulic motor 104. Simultaneously, the internal combustion engine 101 drives the open hydraulic pump 103. The working medium flows, as indicated by the arrows, through the open hydraulic pump 103, the filter 105, the cooler 106, and then back to the open hydraulic pump 103, forming an open loop. Because hydraulic motor 104 and closed-loop hydraulic pump 102 experience internal leakage, leading to loss of working medium, open-loop hydraulic pump 103 replenishes working medium to the first closed loop to prevent closed-loop hydraulic pump 102 from absorbing insufficient working medium. In active cable reeling mode, hydraulic motor 104 generates work, outputting kinetic energy to the cable drum to reel in the cable.

[0056] In the active cable-release mode, the internal combustion engine 101 drives the closed-loop hydraulic pump 102. The working medium flows sequentially through the closed-loop hydraulic pump 102, the hydraulic motor 104, the first check valve 107, and then back to the closed-loop hydraulic pump 102, forming a second closed loop. Obviously, the working medium in the first and second closed loops flows in opposite directions. Simultaneously, similar to the active reeling mode, the internal combustion engine 101 drives the open-loop hydraulic pump 103. The working medium flows sequentially through the open-loop hydraulic pump 103, the filter 105, the cooler 106, and then back to the open-loop hydraulic pump 103, forming an open loop. The open-loop hydraulic pump 103 replenishes the working medium in the second closed loop. In the active cable-release mode, the hydraulic motor 104 generates work, outputting kinetic energy to the cable drum to release the cable.

[0057] In the passive cable-releasing mode, the primary power source for the towing winch system is the energy input from the external anchor chain to the cable drum. The main function of the towing winch hydraulic system is converted to auxiliary power for the hydraulic motor 104, achieving dynamic braking. Simultaneously, the passively input kinetic energy is converted into heat and exchanged within the towing winch hydraulic system through the cooler 106. Specifically, the system's passive power is compared with the active power. If the set conditions are met, the internal combustion engine 101 drives the open hydraulic pump 103. The working medium flows in the following order: open hydraulic pump 103, hydraulic motor 104, filter 105, cooler 106, and then back to the open hydraulic pump 103. In other words, the open hydraulic pump 103 pumps the working medium to the hydraulic motor 104. The hydraulic motor 104, under the energy input from the cable drum, increases the pressure of the working medium. This effectively converts the received external kinetic energy into thermal energy for the working medium, which enters the hydraulic system. After being filtered by the filter 105 and cooled by the cooler 106, the working medium returns to the open hydraulic pump 103, completing the system cycle. The hydraulic motor 104 provides auxiliary power for dynamic braking. It should be noted that in this case, the working medium can also flow in the second closed loop, which is equivalent to combining an open system with a closed system to consume passive power input.

[0058] If the set conditions are not met, the working medium flows in the second closed loop direction, namely, the working medium flows in the order of closed hydraulic pump 102, hydraulic motor 104, first check valve 107, and then back to closed hydraulic pump 102. Closed hydraulic pump 102 inputs the received energy to internal combustion engine 101 through a coupling. Alternatively, internal combustion engine 101 drives open hydraulic pump 103, and the working medium flows in the order of open hydraulic pump 103, hydraulic motor 104, filter 105, cooler 106, and then back to open hydraulic pump 103. In other words, if the set conditions are not met, either the closed system or the open system can be selected to consume the passive power input.

[0059] The closed hydraulic pump 102 transmits the received energy to the internal combustion engine 101 via a coupling. Specifically, the pressure differential between the two oil ports of the closed hydraulic pump 102 generates a rotational torque in the same direction as the torque of the internal combustion engine 101, effectively rotating the internal combustion engine 101 and thus transmitting the received energy. Under normal circumstances, the pressure differential between the two oil ports of the closed hydraulic pump 102 generates a rotational torque in the opposite direction to the torque of the internal combustion engine 101, thereby hindering its rotation.

[0060] As an example and not a limitation, the set condition can be that the passive power of the system is greater than 120% of the active power. Specifically, the passive power and active power of the system are compared. If the passive power is greater than 120% of the active power, an open system is preferred, or an open system is selected to operate in combination with a closed system to consume the passive power input. If the passive power is not greater than 120% of the active power, a closed system or an open system is selected to consume the passive power input. It is easy to understand that the set condition can also be that the passive power of the system is greater than 125% or 130% of the active power, which is set according to actual working conditions.

[0061] When the large-tonnage towing winch hydraulic system 100 is in operation, the filter 105 is always in operation to clean the working medium and ensure the stability of the system operation.

[0062] In some examples, the first one-way valve 107 is a hydraulically controlled one-way valve, which can easily achieve reverse conduction of the working medium.

[0063] In some examples, the large-tonnage towing winch hydraulic system 100 further includes a first reversing valve 108. The first reversing valve 108 is used to control the flow direction of the first check valve 107, thereby changing the flow direction of the working medium. The first reversing valve 108 can be a solenoid valve. When the first reversing valve 108 is energized to control the first check valve 107 to open in the opposite direction, the working medium circulates in a second closed loop.

[0064] In some examples, the large-tonnage towing winch hydraulic system 100 further includes a second check valve 109. Second check valve 109 is connected between the closed and open systems. In active reeling mode, as shown, the open hydraulic pump 103 pumps working medium through the second check valve 109 to replenish the first closed loop and then to the hydraulic motor 104. In passive payout mode, if the passive power exceeds 120% of the active power, the working medium flows from the open hydraulic pump 103 to the hydraulic motor 104 through the second check valve 109.

[0065] In some examples, the large-tonnage towing winch hydraulic system 100 also includes a third one-way valve 110. This third one-way valve 110 is connected between the closed and open systems. In the active cable-releasing mode, as shown in the figure, the open hydraulic pump 103 pumps working medium through the third one-way valve 110 to replenish the second closed loop, where it then flows into the closed hydraulic pump 102.

[0066] In some examples, the large-tonnage towing winch hydraulic system 100 further includes a first relief valve 111 connected in series between the open hydraulic pump 103 and the filter 105. In the active cable-reeling and active cable-releasing modes, the internal combustion engine 101 drives the open hydraulic pump 103, and the working medium flows sequentially through the open hydraulic pump 103, the first relief valve 111, the filter 105, the cooler 106, and then back to the open hydraulic pump 103, forming an open loop.

[0067] In some examples, the large-tonnage towing winch hydraulic system 100 further includes a second reversing valve 112 for controlling the operation of the first relief valve 111. The second reversing valve 112 can be a solenoid valve. In the active cable-reeling mode and the active cable-releasing mode, the second reversing valve 112 is energized to control the operation of the first relief valve 111, and the working medium enters the filter 105 through the first relief valve 111.

[0068] In some examples, the large-tonnage towing winch hydraulic system 100 also includes a second relief valve 113 connected in series between the hydraulic motor 104 and the filter 105. In the passive cable-releasing mode, if the specified conditions are met (passive power is greater than 120% of active power), the internal combustion engine 101 drives the open-loop hydraulic pump 103. The working medium flows sequentially through the open-loop hydraulic pump 103, the hydraulic motor 104, the second relief valve 113, the filter 105, the cooler 106, and then back to the open-loop hydraulic pump 103. At this time, the first reversing valve 108 is de-energized, the first solenoid valve is closed, and the energy received by the hydraulic motor 104 is dissipated through heat exchange in the cooler 106. The closed-loop hydraulic pump 102 is in a zero-displacement operating state. If the passive cable-releasing speed is further increased, the first reversing valve 108 is energized and the first solenoid valve is turned on. The pressurized working medium pumped by the hydraulic motor 104 flows back to the closed hydraulic pump 102 via the first one-way valve 107. The closed hydraulic pump 102 is in a full-displacement working state. Part of the passively input kinetic energy is fed back to the internal combustion engine 101 by the closed hydraulic pump 102, and further fed back to the onboard power grid, or driven to be consumed by the flywheel of the internal combustion engine 101.

[0069] In some examples, the second relief valve 113 is a safety relief valve or a proportional relief valve.

[0070] In some examples, the large-tonnage winch hydraulic system 100 further includes an accumulator 114 connected to the oil suction line of the open hydraulic pump 103. The accumulator 114 can improve oil suction performance. During the oil suction process of the open hydraulic pump 103, if there is pressure fluctuation in the oil suction line or the hydraulic pump is running at high speed, resulting in delayed oil suction, the accumulator 114 can release stored oil to replenish the suction oil, thereby maintaining the pressure in the oil suction line of the open hydraulic pump 103 and ensuring that the open hydraulic pump 103 can stably suck oil throughout the entire operation process.

[0071] In some examples, the open circuit hydraulic pump 103 can be configured to increase or decrease its displacement individually based on the passive cable payout speed requirements of a specific device.

[0072] The present invention provides a hydraulic system for a large-tonnage towing winch, comprising a closed system and an open system. The closed system is used for active cable retraction and release under normal working conditions, and the open system can be used for anchoring or anchoring conditions. The closed system performs positive work, providing cable retraction speed and power to overcome the gravity of the cable; the open system performs negative work, consuming the increase in cable release speed and load caused by the gravity of the anchor cable through dynamic braking, thereby achieving controllable active cable retraction and passive cable release and anchoring through this combined application. The combination of the open system and the closed system can consume a passive power input capacity of up to 3 to 4 times the active output power of the closed system. In addition, the system is designed in a way that the working medium is stored in the pipeline. By increasing the diameter of the system pipeline, the working medium used by the system is stored in the pipeline system, which can eliminate the need for an oil storage tank and avoid contact between the working medium and the external environment, thereby further improving the cleanliness of the working medium.

[0073] It will be apparent to those skilled in the art that various modifications and variations may be made to the above exemplary embodiments of the present invention without departing from the spirit and scope of the present invention. Therefore, it is intended that the present invention cover modifications and variations of the present invention that fall within the scope of the appended claims and their equivalent technical solutions.

Claims

1. A large-tonnage towing winch hydraulic system, characterized in that: The large-tonnage towing winch hydraulic system comprises an internal combustion engine, a closed hydraulic pump, an open hydraulic pump, a hydraulic motor, a filter, a cooler, a first one-way valve, and system pipeline accessories. The large-tonnage towing winch hydraulic system can be switched between an active cable-reeling mode, an active cable-releasing mode, and a passive cable-releasing mode. In the active cable reeling mode, the internal combustion engine drives the closed hydraulic pump to operate, and the working medium flows in the order of the closed hydraulic pump, the first one-way valve, the hydraulic motor, and then returns to the closed hydraulic pump, forming a first closed loop; at the same time, the internal combustion engine drives the open hydraulic pump to operate, and the working medium flows in the order of the open hydraulic pump, the filter, the cooler, and then returns to the open hydraulic pump, forming an open loop, and the open hydraulic pump replenishes the working medium to the first closed loop; In the active cable-releasing operating mode, the internal combustion engine drives the closed hydraulic pump to operate, and the working medium flows in the following order: the closed hydraulic pump, the hydraulic motor, the first one-way valve, and then returns to the closed hydraulic pump, forming a second closed loop. Simultaneously, the internal combustion engine drives the open hydraulic pump to operate, and the working medium flows in the following order: the open hydraulic pump, the filter, the cooler, and then returns to the open hydraulic pump, forming an open loop. The open hydraulic pump replenishes the working medium to the second closed loop. In the passive cable-releasing working mode, the passive power and active power of the system are compared. If the set conditions are met, the internal combustion engine drives the open hydraulic pump to operate, and the working medium flows in the order of the open hydraulic pump, the hydraulic motor, the filter, the cooler, and then back to the open hydraulic pump; If the set conditions are not met, the working medium flows in the direction of the second closed loop, and the closed hydraulic pump inputs the received energy into the internal combustion engine; or the internal combustion engine drives the open hydraulic pump to operate, and the working medium flows in the direction of the open hydraulic pump, the hydraulic motor, the filter, the cooler, and then returns to the open hydraulic pump.

2. The large-tonnage towing winch hydraulic system according to claim 1, characterized in that: The first one-way valve is a hydraulically controlled one-way valve.

3. The large-tonnage towing winch hydraulic system according to claim 2, characterized in that: The large-tonnage towing winch hydraulic system further includes a first reversing valve, which is used to control the flow direction of the first one-way valve to change the flow direction of the working medium.

4. The large-tonnage towing winch hydraulic system according to claim 1, characterized in that: The large-tonnage towing winch hydraulic system further includes a second one-way valve. In the active retraction working mode, the open hydraulic pump replenishes the working medium to the first closed loop through the second one-way valve.

5. The large-tonnage towing winch hydraulic system according to claim 1, characterized in that: The large-tonnage towing winch hydraulic system further includes a third one-way valve. In the active cable-releasing working mode, the open hydraulic pump replenishes the working medium to the second closed loop through the third one-way valve.

6. The large-tonnage towing winch hydraulic system according to claim 1, characterized in that: The large-tonnage towing winch hydraulic system further includes a first relief valve; In the active cable-reeling mode and the active cable-releasing mode, the internal combustion engine drives the open hydraulic pump to operate, and the working medium flows sequentially through the open hydraulic pump, the first relief valve, the filter, the cooler, and then back to the open hydraulic pump, forming the open loop.

7. The large-tonnage towing winch hydraulic system according to claim 6, characterized in that: The large-tonnage towing winch hydraulic system further includes a second reversing valve for controlling the action of the first overflow valve.

8. The large-tonnage towing winch hydraulic system according to claim 1, characterized in that: The large-tonnage towing winch hydraulic system further includes a second relief valve; In the passive cable-releasing mode, the passive power and active power of the system are compared. If the set conditions are met, the internal combustion engine drives the open hydraulic pump to operate, and the working medium flows in the order of the open hydraulic pump, the hydraulic motor, the second relief valve, the filter, the cooler, and then back to the open hydraulic pump.

9. The large-tonnage towing winch hydraulic system according to claim 8, characterized in that: The second relief valve is a safety relief valve or a proportional relief valve.

10. The large-tonnage towing winch hydraulic system according to claim 1, characterized in that: The large-tonnage towing winch hydraulic system further comprises an accumulator connected to the oil suction line of the open hydraulic pump.

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