Hydraulic energy saving system for submersible and method of use

Abstract

The present application relates to a kind of submersible hydraulic energy-saving system and use method, including underwater hydraulic source, the output of the underwater hydraulic source is connected high-pressure filter by pipeline, the output of high-pressure filter is branched into two ways, one way is connected with large flow actuator control valve box, another way is connected with check valve, the output of check valve is connected with energy accumulator assembly and small flow actuator control valve box respectively;While underwater hydraulic source and small flow actuator control valve box and large flow actuator control valve box are connected with the pipeline of filter on it.Set up filter can effectively avoid the pressure and flow loss generated by overflow of hydraulic system, reduce system heating, maximum limit energy saving submersible.

Description

Technical Field

[0001] This invention relates to the field of hydraulic energy-saving systems for submersibles, and in particular to a hydraulic energy-saving system for submersibles and its usage method. Background Technology

[0002] Hydraulic systems are widely used in various underwater equipment due to their high energy density, simple structure, and high product reliability.

[0003] With the development of deep-sea pressure compensation technology, various submersibles have also adopted hydraulic systems as the preferred choice for power supply and motion control of various mechanisms.

[0004] Currently, gear pumps are widely used in submersible hydraulic systems due to their simple structure and high tolerance to oil contamination. However, this system has two drawbacks: When the amount of oil required by the control circuit is small, the fixed displacement pump always outputs at full flow. The excess flow is unloaded from the relief valve at an extremely high relief valve opening pressure, which causes the hydraulic system to heat up and noise to increase dramatically, resulting in a huge waste of the battery energy carried by the submersible. The maximum working pressure of the hydraulic system is set entirely by the relief valve. If the relief valve malfunctions and opens too early, it will unload at a lower pressure, resulting in insufficient driving force for the actuators in the control circuit, which will then be unable to operate. If it does not open at the set pressure, the hydraulic system pressure may continue to rise after the actuators in the control circuit have reached their positions, potentially exceeding the maximum working pressure of the components in the hydraulic system and thus damaging the hydraulic components. Summary of the Invention

[0005] In response to the shortcomings of the existing production technology, the applicant provides a hydraulic energy-saving system and method for use for submersibles, which can effectively avoid pressure and flow loss caused by overflow in the hydraulic system, reduce system heat generation, and maximize energy conservation in the submersible.

[0006] The technical solution adopted in this invention is as follows: A submersible hydraulic energy-saving system includes an underwater hydraulic power source. The output port of the underwater hydraulic power source is connected to a high-pressure filter via a pipeline. The output port of the high-pressure filter branches into two paths: one path connects to a high-flow actuator control valve box, and the other path connects to a check valve. The output ports of the check valves are respectively connected to an accumulator assembly and a low-flow actuator control valve box. Filters are also installed on the pipelines connecting the underwater hydraulic power source to the low-flow actuator control valve box and the high-flow actuator control valve box.

[0007] Its further technical solution lies in: The control valve box of the low-flow actuator includes a No. 1 solenoid directional valve, a No. 2 solenoid directional valve, and a No. 3 solenoid directional valve arranged in parallel. The output ports AB of each solenoid directional valve are connected to the inlet and outlet ports of the low-flow actuator through a bidirectional speed regulation and self-locking valve group.

[0008] The control valve box of the low-flow actuator also includes a low-pressure relay and a high-pressure relay.

[0009] The high-flow actuator control valve box includes a No. 4 solenoid directional valve and a No. 5 solenoid directional valve arranged in parallel. The AB ports of each solenoid directional valve are connected to the inlet and outlet ports of the high-flow actuator through a speed regulating valve group. At the same time, the oil circuit of the high-flow actuator is equipped with a bidirectional safety valve group and a pressure comparison shuttle valve.

[0010] The high-flow actuator control valve box also includes a No. 6 solenoid directional valve and a No. 7 solenoid directional valve arranged in parallel. The No. 7 solenoid directional valve is used for no-load start-up of the underwater hydraulic source, and the No. 6 solenoid directional valve is used to select whether the hydraulic source output is in low-pressure high-flow mode or high-pressure variable-flow mode.

[0011] The hydraulic power source includes an underwater DC motor, a variable displacement pump, a first safety valve, and a normally closed ball valve. The underwater DC motor and the first safety valve are connected to the variable displacement pump. The first safety valve is used to prevent the hydraulic system from overpressure when the high pressure cut-off function of the variable displacement pump fails, serving as a backup means to set the maximum working pressure of the system. The normally closed ball valve is used for opening and closing the oil tank.

[0012] The main body of the accumulator assembly is the accumulator itself. The accumulator is connected to a normally open ball valve, a pressure gauge, a second safety valve, and a normally closed ball valve via a management system. The second safety valve sets the maximum oil filling pressure of the accumulator to protect it. When the submersible completes its operation and is recovered to the deck, if there is still high-pressure oil in the accumulator, the normally closed ball valve can be opened to release the pressure. The pressure in the accumulator is monitored in real time using the pressure gauge. When the pressure gauge shows zero pressure, the normally closed ball valve is closed. When the pressure gauge is damaged and needs to be replaced, the normally open ball valve can be closed to replace the pressure gauge.

[0013] A method for using a submersible hydraulic energy-saving system includes the following operating procedures: S1. Hydraulic system no-load start: When the hydraulic system is needed, the submersible operator opens the No. 7 solenoid directional valve, which connects the load-sensitive oil circuit of the variable oil pump directly to the oil tank of the hydraulic source. At this time, the motor is powered on, driving the variable oil pump to operate with extremely low output pressure and near-zero displacement. The variable oil pump requires very little input power, and the motor starts smoothly. S2. The hydraulic system operates in a low-pressure, high-flow mode: When the hydraulic system needs to supply oil to the actuator with a large flow demand but a small load, first press S1 to complete the no-load start of the hydraulic system, close the No. 7 solenoid directional valve, open the No. 6 solenoid directional valve, and open the No. 4 or No. 5 solenoid directional valve. The pressure required by the actuator to drive the load is directly transmitted to the load-sensitive oil circuit of the variable oil pump through the shuttle valve. At this time, the variable oil pump outputs hydraulic oil at a pressure slightly higher than that required by the actuator to operate. The output flow of the variable oil pump matches the flow set by the speed control valve. The hydraulic system has no additional pressure or flow loss. S3. The hydraulic system operates in high-pressure energy-saving mode: When the hydraulic system needs to supply oil to the actuator with a small flow requirement but a large load, first complete the no-load start of the hydraulic system according to step S1, and close the No. 7 solenoid directional valve. At this time, the load-sensitive oil circuit of the variable oil pump is directly connected to the output oil circuit of the variable oil pump. The variable oil pump outputs hydraulic oil at maximum pressure. At this time, the hydraulic oil enters the accumulator through the check valve. The accumulator is filled with oil. When the pressure in the accumulator exceeds the pressure set by the high-pressure relay, the high-pressure relay sends an electrical signal and automatically opens the No. 7 solenoid directional valve, so that the load-sensitive oil circuit of the variable oil pump is connected to the oil tank of the hydraulic source again. The variable oil pump operates at low pressure and close to zero displacement. At this time, opening the No. 1, No. 2, or No. 3 solenoid directional valve allows hydraulic oil to enter the actuator through the corresponding solenoid directional valve and the bidirectional speed regulating and self-locking valve group in the solenoid valve box, driving the actuator to move. When the pressure in the accumulator is lower than the set pressure of the low-pressure relay, the low-pressure relay sends an electrical signal to automatically close the No. 7 solenoid directional valve. At this time, the load-sensitive oil circuit of the variable oil pump is directly connected to the output oil circuit of the variable oil pump. The variable oil pump outputs hydraulic oil at maximum pressure to charge the accumulator and supply oil to the actuator. When the pressure in the accumulator exceeds the set pressure of the high-pressure relay, the high-pressure relay sends an electrical signal again to automatically open the No. 7 solenoid directional valve. The load-sensitive oil circuit of the variable oil pump is connected to the output oil circuit of the variable oil pump again, and the load-sensitive variable pump operates at low pressure close to zero displacement again. S4. Manual unloading of the accumulator: After the submersible completes its operation and is recovered to the deck, if there is still high-pressure oil in the accumulator, the normally closed ball valve can be opened to connect the accumulator directly to the hydraulic power source's oil tank, thus depressurizing the accumulator. The pressure in the accumulator can be observed in real time through a pressure gauge. When the pressure gauge shows zero pressure, the normally closed ball valve should be closed. If the pressure gauge is damaged and needs to be replaced, the normally open ball valve can be closed to replace the pressure gauge.

[0014] The beneficial effects of this invention are as follows: This invention features a compact and rational structure, and is easy to operate. It uses a DC motor to drive a load-sensitive variable pump as a power source. This power source can output hydraulic oil in two modes: low-pressure high-flow and high-pressure energy-saving. When the connected end effector requires a large flow rate but has a small load to overcome, the low-pressure high-flow mode can be used. When the end effector requires a small flow rate but has a large load to overcome, the accumulator, which is automatically filled with oil when idle, can be used for oil supply. This avoids pressure and flow loss caused by overflow in the hydraulic system, reduces system heat generation, and maximizes energy conservation for the submersible.

[0015] The present invention also has the following advantages: (1) The present invention adopts the hydraulic oil tank pressure compensation method, so that the internal pressure of the hydraulic system is always slightly greater than the external pressure, so that the hydraulic system can be designed according to the conventional hydraulic system and used in any water depth.

[0016] (2) The present invention can accurately control the output pressure and flow rate of the variable oil pump.

[0017] (3) The present invention enables the output energy of the hydraulic system to be used to overcome the load of the actuator, avoiding the heat generated by the hydraulic system due to excessive output pressure or flow, thus saving the energy of the submersible to a great extent and extending the underwater use time.

[0018] (4) The present invention allows the driver to automatically switch the working mode of the hydraulic system by simply using a button.

[0019] (5) The present invention designs an automatic oil filling function for the accumulator by automatically detecting the pressure of the accumulator, which simplifies the operation process of the hydraulic system.

[0020] (6) The present invention provides speed control, overload protection and position self-locking functions for hydraulic actuators by setting speed control valve group, safety valve group and balance valve group in hydraulic circuit. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the overall system structure of the present invention.

[0022] Figure 2 This is a system structure diagram of the underwater hydraulic power source of the present invention.

[0023] Figure 3 This is a system structure diagram of the energy storage component of the present invention.

[0024] Figure 4 This is a system structure diagram of the control valve box for the small flow actuator of the present invention.

[0025] Figure 5 This is a system structure diagram of the control valve box for the high-flow actuator of the present invention.

[0026] The components include: 1. Underwater hydraulic power source; 2. High-pressure filter; 3. Filter; 4. Check valve; 5. Accumulator assembly; 6. Small flow actuator control valve box; 7. Self-locking valve assembly; 8. Small flow actuator; 9. Large flow actuator control valve box; 10. Two-way safety valve assembly; 11. Speed ​​regulating valve assembly; 12. First pressure comparison shuttle valve; 13. Large flow actuator; 14. Second pressure comparison shuttle valve. 101. Underwater DC motor; 102. Variable displacement oil pump; 103. Safety valve No. 1; 104. Ball valve; 501. Accumulator; 502. Pressure gauge; 503. Normally open ball valve; 504. Safety valve No. 2; 505. Normally closed ball valve; 601. Solenoid directional valve No. 1; 602. Solenoid directional valve No. 2; 603. Solenoid directional valve No. 3; 604. Low-pressure relay; 605. High-pressure relay; 901, No. 4 solenoid directional valve; 902, No. 5 solenoid directional valve; 903, No. 6 solenoid directional valve; 904, No. 7 solenoid directional valve. Detailed Implementation

[0027] The specific embodiments of the present invention will now be described with reference to the accompanying drawings.

[0028] like Figures 1-5 As shown, the submersible hydraulic energy-saving system of this embodiment includes an underwater hydraulic source 1. The output port of the underwater hydraulic source 1 is connected to a high-pressure filter 2 through a pipeline. The output port of the high-pressure filter 2 branches into two paths: one path is connected to a high-flow actuator control valve box 9, and the other path is connected to a one-way valve 4. The output port of the one-way valve 4 is connected to an accumulator assembly 5 and a low-flow actuator control valve box 6, respectively. At the same time, a filter 3 is installed on the pipeline connecting the underwater hydraulic source 1 to the low-flow actuator control valve box 6 and the high-flow actuator control valve box 9.

[0029] The control valve box 6 for the small flow actuator contains a first solenoid directional valve 601, a second solenoid directional valve 602, and a third solenoid directional valve 603 arranged in parallel. The output ports AB of each solenoid directional valve are connected to the inlet and outlet ports of the small flow actuator 8 through a bidirectional speed regulating and self-locking valve group 7.

[0030] The small flow actuator control valve box 6 also includes a low pressure relay 604 and a high pressure relay 605.

[0031] The control valve box 9 of the high-flow actuator contains a No. 4 solenoid directional valve 901 and a No. 5 solenoid directional valve 902 arranged in parallel. The AB ports of each solenoid directional valve are connected to the inlet and outlet ports of the high-flow actuator 13 through the speed regulating valve group 11. At the same time, the oil circuit of the high-flow actuator is equipped with a two-way safety valve group 10 and a first pressure comparison shuttle valve 12.

[0032] The high-flow actuator control valve box 9 also includes a No. 6 solenoid directional valve 903 and a No. 7 solenoid directional valve 904 arranged in parallel. The No. 7 solenoid directional valve 904 is used for no-load start-up of the underwater hydraulic source 1, and the No. 6 solenoid directional valve 903 is used to select the hydraulic source output as either low-pressure high-flow mode or high-pressure variable flow mode.

[0033] The first pressure comparison shuttle valve 12 is connected to one port of the second pressure comparison shuttle valve 14. The second port of the second pressure comparison shuttle valve 14 is connected to the inlet of the sixth solenoid directional valve 903. The first working oil port of the sixth solenoid directional valve 903 is connected to the high pressure filter 2. The second working oil port of the sixth solenoid directional valve 903 is connected to the filter 3.

[0034] The second pressure comparison shuttle valve 14 is connected to the oil inlet of the No. 7 solenoid directional valve 904, the oil return port of the No. 7 solenoid directional valve 904 is connected to the filter 3, and the first working oil port of the No. 7 solenoid directional valve 904 is connected to the load-sensitive oil circuit of the variable oil pump 102.

[0035] The underwater hydraulic power source 1 includes an underwater DC motor 101, a variable oil pump 102, a first safety valve 103, and a ball valve 104. The underwater DC motor 101 and the first safety valve 103 are connected to the variable oil pump 102. The first safety valve 103 is used to prevent the hydraulic system from overpressure when the high pressure cut-off function of the variable oil pump 102 fails, and serves as a backup means to set the maximum working pressure of the system. The ball valve 104 is used as a switch for charging and discharging oil into the oil tank.

[0036] The main body of the accumulator assembly 5 is the accumulator 501. The accumulator 501 is connected to a normally open ball valve 503, a pressure gauge 502, a second safety valve 504, and a normally closed ball valve 505 via a management connection. The second safety valve 504 sets the maximum oil filling pressure of the accumulator 501, which serves to protect the accumulator 501. When the submersible completes its operation and is recovered to the deck, if there is still high-pressure oil in the accumulator 501, the normally closed ball valve 505 can be opened to release the pressure in the accumulator 501. The pressure in the accumulator 501 is monitored in real time through the pressure gauge 502. When the pressure in the pressure gauge 502 shows zero, the normally closed ball valve 505 is closed. When the pressure gauge 502 is damaged and needs to be replaced, the pressure gauge 502 can be replaced simply by closing the normally open ball valve 503.

[0037] The specific structure and function of the submersible hydraulic energy-saving system described in this invention are as follows: As attached Figure 1 As shown, the high-pressure oil output from the underwater hydraulic power source 1 flows into the high-flow actuator control valve box 9 through the high-pressure filter 2; at the same time, the high-pressure oil flows into the accumulator assembly 5 and the low-flow actuator control valve box 6 through the check valve 4.

[0038] The small-flow actuator control valve box 6 contains three Y-type three-position four-way solenoid directional valves: No. 1 solenoid directional valve 601, No. 2 solenoid directional valve 602, and No. 3 solenoid directional valve 603. The output ports AB of each solenoid directional valve are connected to the inlet and outlet ports of the small-flow actuator 8 via a bidirectional speed-regulating and self-locking valve assembly 7. Simultaneously, the small-flow actuator control valve box 6 contains a low-pressure relay 604 and a high-pressure relay 605, both used to monitor the pressure in the accumulator 501 in real time.

[0039] The control valve box 9 of the high flow actuator contains a Y-type three-position four-way solenoid directional valve No. 4 901 and a solenoid directional valve No. 5 902. The AB ports of each solenoid directional valve are connected to the inlet and outlet ports of the high flow actuator 13 through the speed regulating valve group 11. At the same time, the oil circuit of the high flow actuator is equipped with a two-way safety valve group 10 and a first pressure comparison shuttle valve 12.

[0040] The high-flow actuator control valve box 9 contains two two-position four-way solenoid directional valves, namely No. 6 solenoid directional valve 903 and No. 7 solenoid directional valve 904. Solenoid directional valve 904 is used for no-load start-up of underwater hydraulic source 1, and solenoid directional valve 903 is used to select whether the hydraulic source output is in low-pressure high-flow mode or high-pressure variable flow mode.

[0041] The underwater hydraulic power source 1 consists of an underwater DC motor 101, a variable oil pump 102, a first safety valve 103, and a ball valve 104. The underwater DC motor 101 is used to drive the variable oil pump 102 to output high-pressure oil; the first safety valve 103 is used to prevent the hydraulic system from overpressure when the high-pressure cut-off function of the variable oil pump 102 fails, serving as a backup means to set the maximum working pressure of the system; the ball valve 104 is used as a switch for charging and discharging oil into the oil tank.

[0042] The main body of accumulator assembly 5 is accumulator 501. Safety valve 504 sets the maximum oil filling pressure of accumulator 501, protecting it. After the submersible completes its operation and is recovered to the deck, if there is still high-pressure oil in accumulator 501, the normally closed ball valve 505 can be opened to release pressure. The pressure in accumulator 501 is monitored in real time using pressure gauge 502. When the pressure gauge 502 shows zero pressure, the normally closed ball valve 505 is closed. When pressure gauge 502 is damaged and needs replacement, it can be replaced simply by closing the normally open ball valve 503.

[0043] This invention allows the submersible operator to select the hydraulic power supply mode according to the actual needs of the hydraulic system, which can minimize the pressure and flow loss of the hydraulic system, reduce system heat generation, save submersible battery energy, and effectively extend the submersible's underwater operation time.

[0044] In actual work, it is completed through the following steps: S1. Hydraulic system no-load start: As attached Figure 1 As shown, when the hydraulic system is needed, the submersible operator opens the No. 7 solenoid directional valve 904, so that the load-sensitive oil circuit of the variable oil pump 102 is directly connected to the oil tank of the underwater hydraulic source 1. At this time, the underwater DC motor 101 is powered on, driving the variable oil pump 102 to operate with extremely low output pressure and near-zero displacement. The variable oil pump 102 requires very little input power, and the motor can start smoothly.

[0045] S2. The hydraulic system operates in a low-pressure, high-flow mode: As attached Figure 1 As shown, when the hydraulic system needs to supply oil to an actuator with a large flow demand but a small load, first press S1 to complete the no-load start of the hydraulic system, close the No. 7 solenoid directional valve 904, open the No. 6 solenoid directional valve 903, and open the No. 4 solenoid directional valve 901 or the No. 5 solenoid directional valve 902. The pressure required to drive the load of the high-flow actuator 13 is directly transmitted to the load-sensitive oil circuit of the variable oil pump 102 through the first pressure comparison shuttle valve 12. At this time, the variable oil pump 102 outputs hydraulic oil at a pressure slightly higher than that required for the operation of the high-flow actuator 13. The output flow of the variable oil pump 102 matches the set flow of the speed control valve group 11. The hydraulic system has no additional pressure or flow loss.

[0046] S3. The hydraulic system operates in high-pressure energy-saving mode: As attached Figure 1 As shown, when the hydraulic system needs to supply oil to the actuator with a small flow requirement but a large load, first complete the no-load start of the hydraulic system according to step 40201, and close the No. 7 solenoid directional valve 904. At this time, the load-sensitive oil circuit of the variable oil pump 102 is directly connected to the output oil circuit of the variable oil pump 102. The variable oil pump 102 outputs hydraulic oil at maximum pressure. At this time, the hydraulic oil enters the accumulator 501 through the check valve 4. The accumulator 501 is filled with oil. When the pressure in the accumulator 501 exceeds the pressure set by the high-pressure relay 605, the high-pressure relay 605 sends an electrical signal and automatically opens the No. 7 solenoid directional valve 904, so that the load-sensitive oil circuit of the variable oil pump 102 is connected to the oil tank of the underwater hydraulic source 1 again, and the variable oil pump 102 operates at low pressure and close to zero displacement.

[0047] At this time, opening the No. 1 solenoid directional valve 601, the No. 2 solenoid directional valve 602, or the No. 3 solenoid directional valve 603 allows hydraulic oil to enter the actuator through the corresponding solenoid directional valve and the bidirectional speed regulating and self-locking valve group 7 in the solenoid valve box, thus driving the actuator to move. When the pressure in the accumulator 501 is lower than the set pressure of the low-pressure relay 604, the low-pressure relay 604 sends an electrical signal to automatically close the No. 7 solenoid directional valve 904. At this time, the load-sensitive oil circuit of the variable oil pump 102 is directly connected to the output oil circuit of the variable oil pump 102. The variable oil pump 102 outputs hydraulic oil at maximum pressure to charge the accumulator 501 and simultaneously supplies oil to the small-flow actuator 8. When the pressure in the accumulator 501 exceeds the set pressure of the high-pressure relay 605, the high-pressure relay 605 sends an electrical signal again to automatically open the No. 7 solenoid directional valve 904. The load-sensitive oil circuit of the variable oil pump 102 is connected to the output oil circuit of the variable oil pump 102 again, and the load-sensitive variable oil pump 102 operates at low pressure close to zero displacement again.

[0048] S4. Manual unloading of the accumulator: As attached Figure 1 As shown, after the submersible completes its operation and is recovered to the deck, if there is still high-pressure oil in the accumulator 501, the normally closed ball valve 505 can be opened to directly connect the accumulator 501 to the oil tank of the underwater hydraulic power source 1, thus depressurizing the accumulator. The pressure in the accumulator 501 can be monitored in real time using the pressure gauge 502. When the pressure in the pressure gauge 502 shows zero, the normally closed ball valve 505 is closed. When the pressure gauge 502 is damaged and needs to be replaced, it can be replaced simply by closing the normally open ball valve 503.

[0049] This invention can detect the pressure inside the accumulator in real time. When the pressure is lower than the minimum set pressure, the hydraulic power source automatically starts and fills the accumulator with oil in high-pressure mode. When the pressure inside the accumulator is higher than the maximum set value, the hydraulic power source automatically shuts down. When the actuator to be started requires a large flow rate, the hydraulic power source uses a low-pressure, high-flow mode. In this mode, the pressure output by the hydraulic power source is only used to overcome the load resistance, with no pressure loss. The output flow rate is the flow rate required by the actuator, with no flow loss. Thus, there is no heat generation and the energy utilization rate is extremely high. When the actuator to be started requires high pressure and low flow rate, the accumulator can be used directly for oil supply, thus eliminating pressure and flow loss. This method also avoids the drawback of the hydraulic power source having to be constantly running when using actuators with low flow rates.

[0050] The above description is an explanation of the present invention and not a limitation thereof. The scope of the present invention is defined by the claims. Within the scope of protection of the present invention, any form of modification may be made.

Claims

1. A hydraulic energy-saving system for submersibles, characterized in that: The system includes an underwater hydraulic power source (1), the output port of which is connected to a high-pressure filter (2) via a pipeline. The output port of the high-pressure filter (2) is branched into two paths, one of which is connected to a large-flow actuator control valve box (9), and the other is connected to a check valve (4). The output port of the check valve (4) is connected to an accumulator assembly (5) and a small-flow actuator control valve box (6) respectively. Meanwhile, a filter (3) is installed on the pipeline connecting the underwater hydraulic power source (1) to the small-flow actuator control valve box (6) and the large-flow actuator control valve box (9). The small-flow actuator control valve box (6) contains a first electromagnetic directional valve (601), a second electromagnetic directional valve (602), and a third electromagnetic directional valve (603) arranged in parallel. The output ports AB of each electromagnetic directional valve are connected to the inlet and outlet ports of the small-flow actuator (8) via a bidirectional speed regulating and self-locking valve group (7). The main body of the accumulator assembly (5) is the accumulator (501). The accumulator (501) is connected to a normally open ball valve (503), a pressure gauge (502), a second safety valve (504), and a normally closed ball valve (505) through pipelines. The second safety valve (504) sets the maximum oil filling pressure of the accumulator (501) and plays a role in protecting the accumulator (501). When the submersible completes its operation and is recovered to the deck, if there is still high pressure oil in the accumulator (501), the normally closed ball valve (505) can be opened to release the pressure of the accumulator (501). The pressure in the accumulator (501) can be observed in real time through the pressure gauge (502). When the pressure in the pressure gauge (502) shows zero, the normally closed ball valve (505) is closed. When the pressure gauge (502) is damaged and needs to be replaced, the pressure gauge (502) can be replaced simply by closing the normally open ball valve (503). The underwater hydraulic power source (1) includes a variable displacement pump (102); The high-flow actuator control valve box (9) includes a No. 4 solenoid directional valve (901) and a No. 5 solenoid directional valve (902) arranged in parallel. The AB ports of each solenoid directional valve are connected to the inlet and outlet ports of the high-flow actuator (13) through a speed regulating valve group (11). At the same time, the oil circuit of the high-flow actuator is equipped with a two-way safety valve group (10) and a first pressure comparison shuttle valve (12). The high-flow actuator control valve box (9) also includes a No. 6 solenoid directional valve (903) and a No. 7 solenoid directional valve (904) arranged in parallel. The No. 7 solenoid directional valve (904) is used for the underwater hydraulic source (1) to start without load, and the No. 6 solenoid directional valve (903) is used to select the output of the underwater hydraulic source (1) as either low-pressure high-flow mode or high-pressure variable flow mode. The first pressure comparison shuttle valve (12) is connected to one port of the second pressure comparison shuttle valve (14). The second port of the second pressure comparison shuttle valve (14) is connected to the inlet of the sixth solenoid directional valve (903). The first working port of the sixth solenoid directional valve (903) is connected to the high pressure filter (2). The second working port of the sixth solenoid directional valve (903) is connected to the filter (3). The second pressure comparison shuttle valve (14) is connected to the oil inlet of the No. 7 solenoid directional valve (904), the oil return port of the No. 7 solenoid directional valve (904) is connected to the filter (3), and the first working oil port of the No. 7 solenoid directional valve (904) is connected to the load-sensitive oil circuit of the variable oil pump (102). The system has two working modes: high flow rate working mode and low flow rate working mode. In the high flow rate working mode, the underwater hydraulic power source (1) supplies oil to both the high flow rate actuator control valve box (9) and the low flow rate actuator control valve box (6) at the same time. In the low flow rate working mode, the underwater hydraulic power source (1) charges the accumulator assembly (5) through the check valve (4), and the accumulator assembly (5) supplies oil to the low flow rate actuator control valve box (6).

2. The submersible hydraulic energy-saving system as described in claim 1, characterized in that: The control valve box (6) of the low flow actuator also includes a low pressure relay (604) and a high pressure relay (605).

3. The submersible hydraulic energy-saving system as described in claim 2, characterized in that: The underwater hydraulic power source (1) also includes an underwater DC motor (101), a first safety valve (103) and a ball valve (104). The underwater DC motor (101) and the first safety valve (103) are connected to the variable oil pump (102). The first safety valve (103) is used to prevent the hydraulic system from overpressure when the high pressure cut-off function of the variable oil pump (102) fails. It serves as a backup means to set the maximum working pressure of the system. The ball valve (104) is used to switch when filling and draining the oil tank.

4. A method of using the submersible hydraulic energy-saving system as described in claim 3, characterized in that: The following procedures are included: S1. Hydraulic system no-load start: When the hydraulic system is needed, the submersible operator opens the No. 7 solenoid directional valve (904) to connect the load-sensitive oil circuit of the variable oil pump (102) directly to the oil tank of the underwater hydraulic power source (1). At this time, the underwater DC motor (101) is powered on, driving the variable oil pump (102) to operate with extremely low output pressure and near-zero displacement. The variable oil pump (102) requires very little input power, and the motor starts smoothly. S2. The hydraulic system operates in a low-pressure, high-flow mode: When the hydraulic system needs to supply oil to the actuator with a large flow demand but small load, first press S1 to complete the no-load start of the hydraulic system, close the No. 7 solenoid directional valve (904), open the No. 6 solenoid directional valve (903), and open the No. 4 solenoid directional valve (901) or the No. 5 solenoid directional valve (902). The pressure required to drive the load of the large flow actuator (13) is directly transmitted to the load-sensitive oil circuit of the variable oil pump (102) through the first pressure comparison shuttle valve (12). At this time, the variable oil pump (102) outputs hydraulic oil at a pressure higher than that required for the operation of the large flow actuator (13). The output flow of the variable oil pump (102) matches the set flow of the speed control valve group (11). The hydraulic system has no additional pressure or flow loss. S3. The hydraulic system operates in high-pressure energy-saving mode: When the hydraulic system needs to supply oil to the actuator with small flow demand but large load, first complete the no-load start of the hydraulic system according to step S1, and close the No. 7 solenoid directional valve (904). At this time, the load-sensitive oil circuit of the variable oil pump (102) is directly connected to the output oil circuit of the variable oil pump (102). The variable oil pump (102) outputs hydraulic oil at maximum pressure. At this time, the hydraulic oil enters the accumulator (501) through the check valve (4). The accumulator (501) is filled with oil. When the pressure in the accumulator (501) exceeds the pressure set by the high pressure relay (605), the high pressure relay (605) sends an electrical signal and automatically opens the No. 7 solenoid directional valve (904), so that the load-sensitive oil circuit of the variable oil pump (102) is connected to the oil tank of the underwater hydraulic source (1) again. The variable oil pump (102) runs at low pressure close to zero displacement. At this time, opening the No. 1 solenoid directional valve (601), the No. 2 solenoid directional valve (602), or the No. 3 solenoid directional valve (603) allows hydraulic oil to enter the actuator through the corresponding solenoid directional valve and the bidirectional speed regulating and self-locking valve group (7) in the small flow actuator control valve box (6), pushing the actuator to move; when the pressure in the accumulator (501) is lower than the set pressure of the low pressure relay (604), the low pressure relay (604) sends an electrical signal to automatically close the No. 7 solenoid directional valve (904), at which time the load-sensitive oil circuit of the variable oil pump (102) is directly connected to The output oil circuit of the variable oil pump (102) is connected. The variable oil pump (102) outputs hydraulic oil at maximum pressure to charge the accumulator (501) and at the same time supplies oil to the small flow actuator (8). When the pressure in the accumulator (501) exceeds the pressure set by the high pressure relay (605), the high pressure relay (605) sends an electrical signal again and automatically opens the No. 7 solenoid directional valve (904). The load-sensitive oil circuit of the variable oil pump (102) is connected to the output oil circuit of the variable oil pump (102) again, and the variable oil pump (102) runs at low pressure close to zero displacement again. S4. Manual unloading of the accumulator: After the submersible completes its operation and is recovered to the deck, if there is still high-pressure oil in the accumulator (501), the normally closed ball valve (505) can be opened to connect the accumulator (501) directly to the oil tank of the underwater hydraulic power source (1), and the accumulator will be depressurized. The pressure in the accumulator (501) can be observed in real time through the pressure gauge (502). When the pressure in the pressure gauge (502) shows zero, the normally closed ball valve (505) is closed. When the pressure gauge (502) is damaged and needs to be replaced, the pressure gauge (502) can be replaced simply by closing the normally open ball valve (503).

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