A hydraulic direct-drive buoyancy and center of gravity control system and method for submersibles

Abstract

This invention discloses a hydraulic direct-drive buoyancy and center of gravity adjustment system and method for submersibles. The system includes an outer shell pre-filled with inert gas at a certain pressure. Inside the outer shell are a bidirectional rotary motor, a bidirectional hydraulic pump, and two or more inner oil bladders. The bidirectional hydraulic pump is driven by the bidirectional rotary motor. Both ends of the bidirectional hydraulic pump are connected to an outer oil bladder outside the outer shell via oil circuits and a two-position two-way solenoid valve. The outer oil bladder is filled with hydraulic oil. The system disclosed in this invention achieves an integrated design of the submersible's center of gravity position and buoyancy adjustment device, simplifying the system structure, through the two inner oil bladders located at both ends of the bidirectional hydraulic pump inside the outer shell and the outer oil bladder outside the outer shell.

Description

Technical Field

[0001] This invention belongs to the field of diving equipment, and specifically relates to a hydraulic direct-drive buoyancy and center of gravity control system and method for submersibles. It can also be used for underwater equipment such as buoys, underwater robots, and gliders. Background Technology

[0002] Modern marine environmental monitoring and resource development rely heavily on various high-performance underwater detection equipment and tools. Among these, buoyancy adjustment systems and center of gravity adjustment systems are crucial components, playing a key role in the equipment's navigation and operation. For operational underwater equipment, it is necessary not only to adjust the diving depth in real time but also to adjust its pitch angle during movement. These adjustments can be achieved through a hybrid buoyancy system that regulates weight, volume, and center of gravity position.

[0003] Currently, there are three main types of buoyancy adjustment for submersibles: weight-controlled, volume-controlled, and a combination of weight and volume control. The more mature methods for center-of-gravity / buoyancy adjustment primarily involve moving weights and adjusting the fluid. Essentially, center-of-gravity adjustment changes the internal mass distribution of the submersible to adjust its center of gravity. However, current submersible buoyancy and center-of-gravity / buoyancy adjustments are implemented as separate modules, with each system structure isolated and functioning independently. This results in complex components, large volume, and numerous drawbacks such as low control precision and inaccurate monitoring.

[0004] Chinese patent "A Buoyancy-Center of Gravity Adjustment and Buoyancy Adjustment Device for Submersibles (Publication No. CN107891957 A)" describes a device for adjusting the buoyancy-center of gravity and buoyancy of a submersible. Its characteristic is the use of hydraulic drive, utilizing two or more oil bladders to achieve buoyancy-center of gravity and buoyancy adjustment by controlling the volume changes of their respective bladders. This patent discloses a highly complex design, occupies a large volume, has a limited buoyancy adjustment range, and suffers from problems such as high hydraulic pump operating pressure (≥ water depth pressure), resulting in unutilized water depth pressure. Based on existing technology, it cannot adequately meet the needs of submersibles in terms of comprehensive buoyancy-center of gravity and buoyancy adjustment. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a hydraulic direct-drive buoyancy and center of gravity control system and method for submersibles.

[0006] The present invention adopts the following technical solution:

[0007] An improved hydraulic direct-drive buoyancy and center of gravity control system for a submersible includes an outer shell pre-filled with inert gas at a certain pressure. The outer shell also houses a bidirectional rotary motor, a bidirectional hydraulic pump, and two or more inner oil bladders. The bidirectional hydraulic pump is driven by the bidirectional rotary motor. Both ends of the pump are connected to outer oil bladders outside the shell via oil circuits and a two-position two-way solenoid valve. The outer oil bladders are filled with hydraulic oil. Each inner oil bladder is equipped with two corresponding two-position two-way solenoid valves. Each inner oil bladder is connected in parallel to its corresponding two two-position two-way solenoid valves via oil circuits. These two two-position two-way solenoid valves are connected to both ends of the bidirectional hydraulic pump via oil circuits. The operation of the bidirectional rotary motor and the switching of the two-position two-way solenoid valves are controlled by a control system within the outer shell. The power supply within the outer shell powers all components within the system.

[0008] Furthermore, a pressure sensor is installed on the outer surface of the housing, and this pressure sensor is electrically connected to the control system inside the housing.

[0009] Furthermore, the two ends of the bidirectional hydraulic pump are connected to the actuator outside the housing via oil circuits and a two-position two-way solenoid valve, respectively.

[0010] Furthermore, one or more through holes are opened on the outer shell, each through hole is sealed by an elastic air bladder, each elastic air bladder is filled with inert gas at different pressures, and the air pressure in each elastic air bladder is higher than the air pressure in the outer shell. The elastic air bladder is in contact with the inside and outside of the outer shell through the porous shell covering it.

[0011] Furthermore, there are two internal oil bladders, located at both ends of the bidirectional hydraulic pump within the outer casing.

[0012] A method for adjusting buoyancy and center of gravity using a hydraulic direct drive system for submersibles, applicable to the aforementioned system, with the following improvements:

[0013] When diving is required: if the gas pressure in each elastic airbag is greater than or equal to the external water environment pressure, the control system controls the two-position two-way solenoid valves c(3), f(6), g(7) to open and the two-position two-way solenoid valves d(4), e(5), h(8) to close. The bidirectional rotary motor rotates clockwise to make the bidirectional hydraulic pump draw hydraulic oil from the outer oilbag into the inner oilbags I(11a) and II(11b); or the control system controls the two-position two-way solenoid valves d(4), e(5), h(8) to open and the two-position two-way solenoid valves c(3), f(6), g(7) to close. The bidirectional rotary motor rotates counterclockwise to make the bidirectional hydraulic pump draw hydraulic oil from the outer oilbag into the inner oilbags I(11a) and II(11b). The volume of the outer oilbag decreases, the system gravity remains unchanged and the buoyancy decreases to achieve diving;

[0014] When the gas pressure inside the elastic airbag begins to be lower than the external water environment pressure, the control system controls the two-position two-way solenoid valves c(3), d(4), e(5), f(6), g(7), and h(8) to close, the bidirectional rotary motor stops, and the external water environment pressure passes through the porous shell in sequence from low pressure to high pressure, squeezing each elastic airbag towards the inside of the shell, so that the system volume is reduced, the buoyancy is reduced, and automatic diving is achieved;

[0015] When buoyancy is required: if the gas pressure in each elastic airbag is less than the external water environment pressure, the control system controls the two-position two-way solenoid valves c(3), f(6), g(7) to close and the two-position two-way solenoid valves d(4), e(5), h(8) to open. The bidirectional rotary motor rotates counterclockwise to make the bidirectional hydraulic pump draw hydraulic oil from the inner oilbags I(11a) and II(11b) into the outer oilbag; or the control system controls the two-position two-way solenoid valves d(4), e(5), h(8) to close and the two-position two-way solenoid valves c(3), f(6), g(7) to open. The bidirectional rotary motor rotates clockwise to make the bidirectional hydraulic pump draw hydraulic oil from the inner oilbags I(11a) and II(11b) into the outer oilbag. The volume of the outer oilbag increases, the system gravity remains unchanged and the buoyancy increases to achieve buoyancy;

[0016] When the gas pressure inside the elastic airbags begins to exceed the external water environment pressure, each elastic airbag expands outward through the porous shell in sequence from high pressure to low pressure, increasing the system volume and buoyancy, thus assisting in floating.

[0017] When it is necessary to tilt to the left: the control system controls the two-position two-way solenoid valves d (4) and e (5) to open, and the two-position two-way solenoid valves c (3), f (6), g (7), and h (8) to close, connecting the one-way oil circuit between the left inner oil bladder I (11a) and the outer oil bladder. The bidirectional rotary motor rotates, causing the bidirectional hydraulic pump to draw hydraulic oil from the outer oil bladder into the left inner oil bladder I (11a). The mass of the left inner oil bladder I (11a) increases, while the mass of the right inner oil bladder II (11b) remains unchanged. The overall center of gravity of the system tilts to the left, achieving left tilting and sinking.

[0018] When it is necessary to recover from the left tilt to the horizontal position: the control system controls the two-position two-way solenoid valves e (5) and f (6) to open, and the two-position two-way solenoid valves c (3), d (4), g (7), and h (8) to close, connecting the oil circuit between the left inner oil bladder I (11a) and the right inner oil bladder II (11b). The bidirectional rotary motor rotates to make the bidirectional hydraulic pump draw hydraulic oil from the left inner oil bladder I (11a) to the right inner oil bladder II (11b) until the mass of the left inner oil bladder I (11a) and the right inner oil bladder II (11b) are equal. The center of gravity of the system shifts to the right to the center position inside the shell, and the horizontal stable position is restored.

[0019] When it is necessary to tilt to the right and sink: the control system controls the two-position two-way solenoid valves c (3) and f (6) to open, and the two-position two-way solenoid valves d (4), e (5), g (7), and h (8) to close, connecting the one-way oil circuit between the right inner oil bladder II (11b) and the outer oil bladder. The bidirectional rotary motor rotates, causing the bidirectional hydraulic pump to draw hydraulic oil from the outer oil bladder into the right inner oil bladder II (11b). The mass of the right inner oil bladder II (11b) increases, while the mass of the left inner oil bladder I (11a) remains unchanged. The overall center of gravity of the system tilts to the right, achieving right tilting and sinking.

[0020] When it is necessary to recover from the right tilt to the horizontal position: the control system controls the two-position two-way solenoid valves e (5) and f (6) to open, and the two-position two-way solenoid valves c (3), d (4), g (7), and h (8) to close, connecting the oil circuit between the left inner oil bladder I (11a) and the right inner oil bladder II (11b). The bidirectional rotary motor rotates to make the bidirectional hydraulic pump draw hydraulic oil from the right inner oil bladder II (11b) into the left inner oil bladder I (11a) until the mass of the left inner oil bladder I (11a) and the right inner oil bladder II (11b) are equal. The center of gravity of the system shifts to the left to the center position inside the shell, and the horizontal stable position is restored.

[0021] The beneficial effects of this invention are:

[0022] The system disclosed in this invention achieves an integrated design of the submersible's center of gravity position and buoyancy adjustment device through two inner oil bladders located at both ends of the bidirectional hydraulic pump within the outer shell and an outer oil bladder outside the outer shell, simplifying the system structure. The elastic air bladders pre-filled with inert gas effectively utilize water depth pressure energy to achieve automatic descent and assisted ascent, achieving energy efficiency. Pre-filling the outer shell with inert gas reduces the pressure on the outer shell, decreasing its weight and volume, and effectively lowers the maximum working pressure of the bidirectional hydraulic pump, facilitating the transfer of hydraulic oil between the inner and outer oil bladders. Furthermore, the working pressure range of the bidirectional hydraulic pump is adjustable.

[0023] The method disclosed in this invention can make full use of water depth pressure energy, improve the system's surfacing and diving efficiency, and also adjust the system's left tilt, right tilt and horizontal attitude. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the pressure compensation system disclosed in Embodiment 1 of the present invention;

[0025] Figure 2 This is a schematic diagram of the pressure compensation system disclosed in Embodiment 2 of the present invention.

[0026] Reference numerals: 1—Bidirectional rotary motor, 2—Bidirectional hydraulic pump, 3—Two-position two-way solenoid valve c, 4—Two-position two-way solenoid valve d, 5—Two-position two-way solenoid valve e, 6—Two-position two-way solenoid valve f, 7—Two-position two-way solenoid valve g, 8—Two-position two-way solenoid valve h, 9, 10—Two-position two-way solenoid valves, 11a—Inner oil bladder I, 11b—Inner oil bladder II, 12—Outer oil bladder, 13—Outer shell, 14—Pressure sensor, A, B, C, D—Elastic air bladders. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0028] Example 1, such as Figure 1 As shown, this embodiment discloses a hydraulic direct-drive buoyancy and center of gravity control system for a submersible, including an outer shell 13. An inert gas of a certain pressure is pre-filled inside the outer shell. A bidirectional rotary motor 1, a bidirectional hydraulic pump 2, and two or more inner oil bladders are also installed inside the outer shell. The bidirectional hydraulic pump is driven by the bidirectional rotary motor. Both ends of the bidirectional hydraulic pump are connected to an outer oil bladder 12 outside the outer shell via oil circuits and a two-position two-way solenoid valve c3 and d4, respectively. The outer oil bladder is filled with hydraulic oil. The inner oil bladders are rationally distributed and arranged within the outer shell. Each inner oil bladder is equipped with two corresponding two-position two-way solenoid valves. Each inner oil bladder is connected in parallel with its corresponding two two-position two-way solenoid valves via oil circuits. These two two-position two-way solenoid valves are respectively connected to both ends of the bidirectional hydraulic pump via oil circuits.

[0029] In this embodiment, there are two inner oil bladders, I11a and II11b, located at both ends of the bidirectional hydraulic pump within the outer casing. Inner oil bladder I11a corresponds to the two-position two-way solenoid valves e5 and g7, and inner oil bladder II11b corresponds to the two-position two-way solenoid valves f6 and h8.

[0030] The operation of the aforementioned bidirectional rotary motor and the switching of each two-position two-way solenoid valve are controlled by the control system inside the housing, and the power supply inside the housing supplies power to the various components within the system.

[0031] A pressure sensor 14 for measuring the pressure of the external water environment is installed on the outer surface of the housing. The pressure sensor is electrically connected to the control system inside the housing and sends the measured external water environment pressure value to the control system inside the housing.

[0032] The two ends of the bidirectional hydraulic pump are connected to the actuator outside the housing via oil circuits and a two-position two-way solenoid valve 9 and 10, respectively.

[0033] Example 2, as Figure 2 As shown, the difference between this embodiment and embodiment 1 is that: more than one through hole is opened on the outer shell, each through hole is sealed by an elastic air bladder, each elastic air bladder is filled with inert gas at different pressures, and the air pressure in each elastic air bladder is higher than the air pressure in the outer shell. The elastic air bladder is in contact with the inside and outside of the outer shell through the porous shell covering it.

[0034] In this embodiment, there are four elastic airbags A, B, C and D.

[0035] This embodiment also discloses a hydraulic direct-drive buoyancy and center of gravity control method for a submersible, applicable to the system of this embodiment. Its principle is that the control system inside the outer shell controls the opening and closing of different two-position two-way solenoid valves according to predetermined logic. By adjusting the amount of oil in the inner oil bladders on both sides, the buoyancy adjustment for overall descent and ascent, and the center of gravity-buoyancy adjustment for pitch and roll movements are completed. When buoyancy increase (decrease) adjustment is required, the hydraulic oil in inner oil bladders I11a and II11b is simultaneously decreased (increased) by an equal amount. When center of gravity-buoyancy adjustment is required, the hydraulic oil in inner oil bladder I11a is increased (decreased) while the hydraulic oil in inner oil bladder II11b is decreased (increased) by an equal amount, thereby changing the system's center of gravity and achieving pitch attitude adjustment. When a constant depth or attitude is required, the two-position two-way solenoid valves 3 and 4 are de-energized, closing the oil passage between inner oil bladders I11a and II11b and the outer oil bladder, ensuring that the volume of inner oil bladders I11a and II11b does not change. Specifically:

[0036] When diving is required: if the gas pressure inside each elastic airbag is greater than or equal to the external water environment pressure, the control system controls the two-position two-way solenoid valves c3, f6, and g7 to open and the two-position two-way solenoid valves d4, e5, and h8 to close. The bidirectional rotary motor rotates clockwise to cause the bidirectional hydraulic pump to draw hydraulic oil from the outer airbag into the inner airbags I11a and II11b; or the control system controls the two-position two-way solenoid valves d4, e5, and h8 to open and the two-position two-way solenoid valves c3, f6, and g7 to close. The bidirectional rotary motor rotates counterclockwise to cause the bidirectional hydraulic pump to draw hydraulic oil from the outer airbag into the inner airbags I11a and II11b. The volume of the outer airbag decreases, the system gravity remains unchanged and the buoyancy decreases, thus achieving diving.

[0037] After hydraulic oil enters the inner oil bladder from the outer oil bladder, the volume of the inner oil bladder increases, while the volume of gas inside the outer shell decreases and the pressure increases. As the gas pressure inside the outer shell gradually exceeds the gas pressure inside each elastic air bladder, the gas inside the outer shell can pass through the porous shell and squeeze each elastic air bladder in sequence from low pressure to high pressure in order to reduce the rate of increase of gas pressure inside the outer shell and achieve pressure regulation.

[0038] When the gas pressure inside the elastic airbags begins to be lower than the external water environment pressure, the control system controls the two-position two-way solenoid valves c3, d4, e5, f6, g7, and h8 to close, the bidirectional rotary motor stops, and the external water environment pressure, in order from low pressure to high pressure, squeezes each elastic airbag through the porous shell towards the inside of the shell, thereby reducing the system volume and buoyancy, and achieving automatic diving.

[0039] When buoyancy is required: if the gas pressure inside each elastic airbag is lower than the external water environment pressure, the control system closes the two-position two-way solenoid valves c3, f6, and g7, and opens the two-position two-way solenoid valves d4, e5, and h8. The bidirectional rotary motor rotates counterclockwise, causing the bidirectional hydraulic pump to draw hydraulic oil from the inner airbags I11a and II11b into the outer airbag; or the control system closes the two-position two-way solenoid valves d4, e5, and h8, and opens the two-position two-way solenoid valves c3, f6, and g7. The bidirectional rotary motor rotates clockwise, causing the bidirectional hydraulic pump to draw hydraulic oil from the inner airbags I11a and II11b into the outer airbag. The volume of the outer airbag increases, the system's gravity remains unchanged, and the buoyancy increases, thus achieving buoyancy.

[0040] After the hydraulic oil enters the outer oil bladder from the inner oil bladder, the volume of the inner oil bladder decreases, the volume of gas inside the outer shell increases and the pressure decreases, and the gas pressure inside each elastic air bladder also decreases. If the gas pressure inside the outer shell is higher than the gas pressure inside some elastic air bladders during this process, the gas inside the outer shell can pass through the porous shell and squeeze each elastic air bladder in sequence from low pressure to high pressure in order to reduce the rate of decrease of the gas pressure inside the outer shell and achieve pressure regulation.

[0041] When the gas pressure inside the elastic airbags begins to exceed the external water environment pressure, each elastic airbag expands outward through the porous shell in sequence from high pressure to low pressure, increasing the system volume and buoyancy, thus assisting in floating.

[0042] When tilt adjustment is required: By adjusting the hydraulic oil volume in the two inner oil bladders, the mass distribution inside the system is changed, thereby adjusting the position of its center of gravity and achieving pitch angle adjustment underwater. In the initial horizontal position of the system, the hydraulic oil volume in inner oil bladders I11a and II11b is the same, and the center of gravity is located at the center of the system, maintaining a stable horizontal attitude.

[0043] When a leftward tilt and sinking is required: the control system controls the two-position two-way solenoid valves d4 and e5 to open, and the two-position two-way solenoid valves c3, f6, g7, and h8 to close, connecting the one-way oil circuit between the left inner oil bladder I11a and the outer oil bladder. The bidirectional rotary motor rotates, causing the bidirectional hydraulic pump to draw hydraulic oil from the outer oil bladder into the left inner oil bladder I11a. The mass of the left inner oil bladder I11a increases, while the mass of the right inner oil bladder II11b remains unchanged. The overall center of gravity of the system tilts to the left, achieving a leftward tilt and sinking.

[0044] When it is necessary to recover from the left tilt to a horizontal attitude: the control system controls the two-position two-way solenoid valves e5 and f6 to open and the two-position two-way solenoid valves c3, d4, g7, and h8 to close, connecting the oil circuit between the left inner oil bladder I11a and the right inner oil bladder II11b. The bidirectional rotary motor rotates in the opposite direction, causing the bidirectional hydraulic pump to draw hydraulic oil from the left inner oil bladder I11a to the right inner oil bladder II11b until the mass of the left inner oil bladder I11a and the right inner oil bladder II11b are equal. The system's center of gravity shifts to the right to the center position inside the outer shell, restoring a horizontal and stable attitude.

[0045] When a rightward tilt and sinking is required: the control system controls the two-position two-way solenoid valves c3 and f6 to open, and the two-position two-way solenoid valves d4, e5, g7, and h8 to close, connecting the one-way oil circuit between the right inner oil bladder II11b and the outer oil bladder. The bidirectional rotary motor rotates, causing the bidirectional hydraulic pump to draw hydraulic oil from the outer oil bladder into the right inner oil bladder II11b. The mass of the right inner oil bladder II11b increases, while the mass of the left inner oil bladder I11a remains unchanged. The overall center of gravity of the system tilts to the right, achieving a rightward tilt and sinking.

[0046] When it is necessary to recover from the rightward tilt to a horizontal attitude: the control system controls the two-position two-way solenoid valves e5 and f6 to open, and the two-position two-way solenoid valves c3, d4, g7, and h8 to close, connecting the oil circuit between the left inner oil bladder I11a and the right inner oil bladder II11b. The bidirectional rotary motor rotates in the opposite direction, causing the bidirectional hydraulic pump to draw hydraulic oil from the right inner oil bladder II11b into the left inner oil bladder I11a, until the left inner oil bladder I11a and the right inner oil bladder II11b have equal mass. The system's center of gravity shifts to the left to the center position inside the outer shell, restoring a horizontal and stable attitude.

[0047] The table below shows the opening (+) and closing (-) logic sequence of the two-position two-way solenoid valves c3, d4, e5, f6, g7, and h8:

[0048]

Claims

1. A method for controlling buoyancy and gravity center of a submersible by oil hydraulic direct drive, which is suitable for a system for controlling buoyancy and gravity center of a submersible by oil hydraulic direct drive, comprising a shell, inert gas with a certain pressure pre-charged in the shell, a bidirectional rotary motor, a bidirectional hydraulic pump and two or more inner oil bags arranged in the shell, the bidirectional hydraulic pump being driven by the bidirectional rotary motor, the two ends of the bidirectional hydraulic pump being connected to an outer oil bag outside the shell through oil paths and a two-position two-way electromagnetic switch valve, the outer oil bag being filled with hydraulic oil, each inner oil bag being provided with two two-position two-way electromagnetic switch valves, each inner oil bag being connected to the two two-position two-way electromagnetic switch valves in parallel through oil paths, and the two two-position two-way electromagnetic switch valves being connected to the two ends of the bidirectional hydraulic pump through oil paths, the operation of the bidirectional rotary motor and the opening and closing of the two-position two-way electromagnetic switch valves being controlled by a control system in the shell, and a power supply in the shell supplying power to each component in the system; one or more through holes are formed on the shell, each through hole being sealed by an elastic air bag, inert gas with different pressures being filled in each elastic air bag, the air pressure in each elastic air bag being higher than the air pressure in the shell, and the elastic air bag being in contact with the shell through a porous shell wrapped outside the elastic air bag; the inner oil bags are two, and are located at the two ends of the bidirectional hydraulic pump in the shell, characterized in that: when diving is needed, if the gas pressure in each elastic air bag is greater than or equal to the external water environment pressure, the control system controls the two-position two-way electromagnetic switch valves c (3), f (6) and g (7) to be opened, and the two-position two-way electromagnetic switch valves d (4), e (5) and h (8) to be closed, the bidirectional rotary motor rotates clockwise to make the bidirectional hydraulic pump suck hydraulic oil from the outer oil bag into the inner oil bags I (11a) and II (11b); or the control system controls the two-position two-way electromagnetic switch valves d (4), e (5) and h (8) to be opened, and the two-position two-way electromagnetic switch valves c (3), f (6) and g (7) to be closed, the bidirectional rotary motor rotates counterclockwise to make the bidirectional hydraulic pump suck hydraulic oil from the outer oil bag into the inner oil bags I (11a) and II (11b), the volume of the outer oil bag decreases, the gravity of the system remains unchanged, the buoyancy decreases, and diving is realized; when the gas pressure in the elastic air bag starts to be less than the external water environment pressure, the control system controls the two-position two-way electromagnetic switch valves c (3), d (4), e (5), f (6), g (7) and h (8) to be closed, and the bidirectional rotary motor to be stopped, the external water environment pressure sequentially extrudes each elastic air bag in the direction of the shell through the porous shell from low pressure to high pressure, the volume of the system decreases, the buoyancy decreases, and automatic diving is realized. When the buoyancy is needed: if the gas pressure in each elastic air bag is less than the external water environment pressure, the control system controls the two-position two-way electromagnetic switch valve c (3), f (6), g (7) to be closed, the two-position two-way electromagnetic switch valve d (4), e (5), h (8) to be opened, and the double-rotating motor rotates counterclockwise to make the double-rotating hydraulic pump suck the hydraulic oil from the inner oil bags I (11a) and II (11b) into the outer oil bag; or the control system controls the two-position two-way electromagnetic switch valve d (4), e (5), h (8) to be closed, the two-position two-way electromagnetic switch valve c (3), f (6), g (7) to be opened, and the double-rotating motor rotates clockwise to make the double-rotating hydraulic pump suck the hydraulic oil from the inner oil bags I (11a) and II (11b) into the outer oil bag, the volume of the outer oil bag increases, the gravity of the system remains unchanged, the buoyancy increases, and the buoyancy increases to realize the buoyancy; When the gas pressure in the elastic air bag starts to be greater than the external water environment pressure, each elastic air bag expands in turn from high pressure to low pressure through the multi-hole shell to the outside of the shell, so that the volume of the system increases, the buoyancy increases, and the buoyancy increases to assist the buoyancy; When the left inclination is needed: the control system controls the two-position two-way electromagnetic switch valve d (4), e (5) to be opened, the two-position two-way electromagnetic switch valve c (3), f (6), g (7), h (8) to be closed, and the left inner oil bag I (11a) and the outer oil bag are connected, the double-rotating motor rotates to make the double-rotating hydraulic pump suck the hydraulic oil from the outer oil bag into the left inner oil bag I (11a), the mass of the left inner oil bag I (11a) increases, the mass of the right inner oil bag II (11b) remains unchanged, the overall center of gravity of the system tilts to the left, and the left inclination is realized. When the left inclination is needed: the control system controls the two-position two-way electromagnetic switch valve e (5), f (6) to be opened, the two-position two-way electromagnetic switch valve c (3), d (4), g (7), h (8) to be closed, and the oil path between the left inner oil bag I (11a) and the right inner oil bag II (11b) is connected, the double-rotating motor rotates to make the double-rotating hydraulic pump suck the hydraulic oil from the left inner oil bag I (11a) into the right inner oil bag II (11b), until the mass of the left inner oil bag I (11a) and the right inner oil bag II (11b) is equal, the center of gravity of the system moves to the right to the center of the outer shell, and the horizontal stable attitude is restored; When the right inclination is needed: the control system controls the two-position two-way electromagnetic switch valve c (3), f (6) to be opened, the two-position two-way electromagnetic switch valve d (4), e (5), g (7), h (8) to be closed, and the one-way oil path between the right inner oil bag II (11b) and the outer oil bag is connected, the double-rotating motor rotates to make the double-rotating hydraulic pump suck the hydraulic oil from the outer oil bag into the right inner oil bag II (11b), the mass of the right inner oil bag II (11b) increases, the mass of the left inner oil bag I (11a) remains unchanged, the overall center of gravity of the system tilts to the right, and the right inclination is realized. When the right tilt needs to be recovered to the horizontal posture: the control system controls the two-position two-way electromagnetic switch valve e (5), f (6) to open, and the two-position two-way electromagnetic switch valve c (3), d (4), g (7), h (8) to close, the oil circuit between the left inner oil bag I (11a) and the right inner oil bag II (11b) is connected, the bidirectional rotating motor rotates to make the bidirectional hydraulic pump suck the hydraulic oil from the right inner oil bag II (11b) into the left inner oil bag I (11a), until the left inner oil bag I (11a) and the right inner oil bag II (11b) are equal in mass, the system center of gravity moves to the center of the shell inside, and the horizontal stable posture is recovered.

2. The method for oil hydraulic direct-drive buoyancy and gravity control of a submersible according to claim 1, characterized in that: A pressure sensor is mounted on the outer surface of the shell, and the pressure sensor is electrically connected with the control system in the shell.

3. The method for oil hydraulic direct drive buoyancy and gravity control of a submersible according to claim 1, wherein: The two ends of the bidirectional hydraulic pump are connected with the execution unit outside the shell through an oil circuit and a two-position two-way electromagnetic switch valve.

Images