A linear heave compensation device based on a double piston double rod accumulator

Abstract

The application designs a linear heave compensation device based on double-piston double-rod accumulator, belongs to the technical field of ocean engineering equipment, adopts double-piston double-rod accumulator as a coupling device of compensation power, has multiple functional cavities, connects a high-pressure gas cylinder group with passive compensation gas cavities of the double-piston double-rod accumulator, thereby providing a passive compensation force on the accumulator piston rod; a bidirectional variable pump is connected with two active compensation liquid cavities of the accumulator, provides an active compensation force with controllable size and direction on the accumulator piston rod through a closed variable pump control speed loop, the passive and active compensation forces jointly overcome the accumulator load and drive the accumulator piston rod to move, thereby indirectly driving the compensation cylinder to realize the heave compensation function; in addition, the deep water high-pressure environment pressure simultaneously acts on the end of the accumulator load pressure liquid cavity piston rod and the compensation cylinder piston rod, and the deep water pressure compensation function is realized through pressure interaction offset. The application realizes multiple operation modes and functions such as passive compensation, active compensation and water pressure compensation, can operate in different working conditions such as on water, under water and deep water area, and has the characteristics of novel structure, compact system, multi-functional integration, high compensation precision and the like.

Description

Technical Field

[0001] The invention relates to a linear heave compensation device based on a double-piston double-rod accumulator, belonging to the technical field of marine engineering equipment. Background Art

[0002] When operating at sea, engineering equipment is subject to the influence of wind, waves, and currents, generating six degrees of freedom. Heave, roll, and pitch, among other factors, cause vertical motion in the load, potentially causing it to collide with the underwater platform or leave a lowered load hanging again. These unexpected situations can cause equipment damage and cable breakage, or even accidents and casualties. To successfully complete offshore operations and maximize the operating window in sea conditions, offshore engineering equipment must be equipped with a heave compensation system.

[0003] Heave compensation systems are categorized by installation method as fixed or mobile, by operating principle as winch-type and hydraulic cylinder-type, and by power supply as passive, active, and a combination of active and passive. The linear compensation system uses a hydraulic cylinder as the actuator, resulting in faster response and more precise control compared to equipment with larger moments of inertia, such as winches.

[0004] Most existing linear compensation systems can only be installed on ships and lack the ability to be mobile or operate underwater. They lack compensation for external water pressure in deepwater, high-pressure environments and struggle to address issues like splash zone compensation and deepwater resonance. Some compensation systems capable of underwater operation often only offer simple passive compensation functions, while some active compensation solutions also suffer from complex structures and large equipment size. Among existing active compensation solutions, using a standard single-rod hydraulic cylinder as a heave compensation cylinder offers a simple and low-cost compensation system. However, due to its limited interior, it lacks the ability to actively control the cylinder's extension and retraction movements. This results in motor-operated conditions during the hydraulic pump's direction change and speed regulation, and significant fluctuations in the working pressure of the cylinder's active chamber, impacting the system's compensation accuracy and operational stability. Using a composite cylinder as a heave compensation cylinder allows for dual-dynamic stroke control, resulting in higher compensation accuracy and a lower pump flow rate during active compensation, making the system easier to control. However, the complex structure and manufacturing process of the composite cylinder lead to high manufacturing costs, reduced service life, and high maintenance costs. Summary of the Invention

[0005] The present invention provides a linear heave compensation device based on a dual-piston dual-rod accumulator, which can meet the compensation performance of offshore working devices, has multiple working modes, can work under different working conditions, and consumes less energy than traditional active compensation devices.

[0006] To achieve the above object, the general idea of the present application is to replace the traditional ordinary compensation hydraulic cylinder or composite compensation cylinder with a double-piston double-rod accumulator and an ordinary compensation hydraulic cylinder, connect the high-pressure cylinder group to the passive compensation gas cavity of the double-piston double-rod accumulator, provide passive compensation force for the load, connect the double-direction variable pump to the two active cavities of the double-piston double-rod accumulator, and provide an active compensation force with variable size and direction by controlling the oil amount in the two active cavities. Meanwhile, a displacement sensor is installed in the gas cavity of the double-piston double-rod accumulator to detect the compensation displacement of the piston, so as to realize displacement closed-loop control in active compensation.

[0007] The technical scheme adopted by the present application is to improve the heave compensation device composed of a hydraulic pump, an ordinary single-rod hydraulic cylinder or a composite cylinder. The ordinary single-rod hydraulic cylinder is replaced by a double-piston double-rod accumulator, and a cylinder group, an oil storage accumulator, an oil supplement accumulator, a low-pressure cylinder, a passive compensation mode switching valve, an active compensation mode switching valve, an oil supplement circuit, a throttle valve block, a displacement sensor, a pressure sensor, an MRU motion posture sensor and a PLC control unit are further added. The low-pressure cylinder is connected to the rodless cavity V1 of the compensation cylinder through a second stop valve. The rod cavity V2 of the compensation cylinder is connected to the load pressure liquid cavity F of the double-piston double-rod accumulator. The cylinder group is connected to the passive compensation gas cavity G of the double-piston double-rod accumulator. The two ports of the double-direction variable pump are connected to the two active compensation liquid cavities H and L of the double-piston double-rod accumulator through the active compensation mode switching valve. The oil discharge port of the double-direction variable pump is connected to the oil supplement circuit through a one-way valve. The oil supplement circuit is composed of an oil storage accumulator, an oil supplement accumulator, an oil supplement pump, a constant-speed motor, a stop valve, a one-way valve, a pressure sensor, a relief valve, first and second cartridge one-way valves and first and second cartridge relief valves. In the oil supplement process, the supplement oil enters from the inlet of the first and second cartridge one-way valves and flows out to the compensation circuit through the side port, so as to supplement the oil for the system. The supplement oil can also supplement the oil for the circuit between the double-piston double-rod accumulator and the compensation cylinder through the seventh stop valve. In order to realize the active and passive switching function of the device, the two high-pressure cavities H and L of the double-piston double-rod accumulator are connected through the passive compensation mode switching valve. The cylinder group is connected to the passive compensation gas cavity G of the double-piston double-rod accumulator through a cylinder switch valve and a throttle valve block.

[0008] The present application has the advantages that:

[0009] 1. The present application realizes various operation modes and functions such as passive compensation, active compensation and deep water pressure compensation, can work in different working conditions such as on water, under water and deep water, has the characteristics of compact structure and multi-functional integration, and the double-piston double-rod accumulator adopts double-piston bearing, has the advantages of simple structure and manufacturing process, good longitudinal stability of the piston rod and long service life.

[0010] 2. An active compensation circuit based on closed-loop pump-controlled speed regulation is constructed by using two volume-coupled active chambers of a bidirectional variable pump and a dual-piston dual-rod accumulator. This realizes active control of the bidirectional motion stroke of the accumulator and the compensation cylinder, solving the problem of large fluctuations in the active chamber working pressure in existing single active chamber compensation schemes.

[0011] 3. The double-piston double-rod accumulator and compensation cylinder adopt low-friction sealing materials and structures, which reduces the impact of seal friction on the performance of conventional passive heave compensation.

[0012] 4. According to different working conditions and sea conditions, the performance of the passive compensation system under special working conditions can be improved by flexibly adjusting the volume stiffness of the working cylinder of the liquid-gas system and the hydraulic damping of the proportional throttle valve block, effectively preventing the problems of resonance and insufficient cylinder movement stroke in the compensation system, and meeting the working needs of conventional wave compensation, splash zone crossing, landing cushioning and other different operation stages.

[0013] 5. In order to prevent the gas cylinder group from suddenly applying a large pressure to the upper piston of the double-piston double-rod accumulator during the preparation stage of the equipment, causing the piston to quickly descend and hit the accumulator, a throttle valve block is connected at the outlet of the gas cylinder group to slowly fill the passive compensation air chamber G with high-pressure gas, which can improve operating stability and reduce impact.

[0014] 6. The safety valve group composed of cartridge valves and relief valves realizes the protection and oil replenishment functions of the active compensation circuit. By giving different pressures to the cartridge valves, the oil is guided to flow into the compensation circuit or back to the oil storage accumulator. Compared with conventional oil replenishment circuits and safety circuits, fewer components are required and the safety factor is higher.

[0015] 7. Compared with the rodless cavity of the compensation cylinder in a vacuum state in the traditional heave compensation system, the present invention adds a low-pressure gas cylinder connected to the rodless cavity of the compensation cylinder. When the system loses load, the piston rod of the compensation cylinder will rise rapidly, and the pressure in the rodless cavity will increase. At this time, the low-pressure gas cylinder will hinder the upward movement of the piston rod, which can improve the operating stability and reduce impact. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a schematic diagram of a linear heave compensation device based on a dual-piston dual-rod accumulator according to the present invention.

[0017] Figure 2 This is a schematic diagram of the double-piston double-rod accumulator and compensation cylinder structure of the present invention.

[0018] Wherein: 1 - double piston double rod accumulator; 1.1 - passive compensation air chamber G; 1.2 - upper piston; 1.3 - active compensation liquid chamber H; 1.4 - inner piston rod; 1.5 active compensation liquid chamber L; 1.6 - lower piston; 1.7 - load pressure liquid chamber F; 1.8 - cylinder; 1.9 - outer piston rod; 2 - first throttle valve block; 3 - first stop valve; 4 - compensation cylinder; 4.1 - compensation cylinder rodless chamber V1; 4.2 - compensation cylinder piston; 4.3 - compensation cylinder rod chamber V2; 4.4 - compensation cylinder piston rod; 4.5 - cylinder; 4.6 - ear ring; 5 - second stop valve; 6 - third stop valve; 7 - low pressure gas cylinder; 8 - pressure sensor; 9 - MRU motion posture sensor; 10 - PLC control unit; 11 - displacement sensor; 12 - cylinder switch valve; 13 - cylinder group; 14 - second throttle valve block; 15 - relief valve; 16 - fourth stop valve; 17 - passive compensation mode switching valve; 18 - active compensation mode switching valve; 19 - first cartridge check valve; 20 - first cartridge overflow valve; 21 - first overflow valve; 22 - oil supplementing accumulator; 23 - fifth stop valve; 24 - oil supplementing pump; 25 - oil storage accumulator; 26 - sixth stop valve; 27 - bidirectional variable pump; 28 - first servo motor; 29 - constant speed motor; 30 - second overflow valve; 31 - second cartridge overflow valve; 32 - second cartridge check valve; 33 - seventh stop valve. DETAILED DESCRIPTION

[0019] The application will be further described in detail below in combination with the drawings and specific embodiments.

[0020] As shown in Figure 1 , 2 , the low pressure gas cylinder (7) is connected with the compensation cylinder rodless chamber V1 through the second stop valve (5), the compensation cylinder rod chamber V2 (4.3) is communicated with the double piston double rod accumulator load pressure liquid chamber F (1.7) through the first throttle valve block (2) and the first stop valve (3), the double piston double rod accumulator passive compensation air chamber G is connected with the cylinder group (13) through the second throttle valve block (14), the fourth stop valve (16) and the cylinder switch valve (12), the relief valve (15) is connected with the fourth stop valve (16) at the inlet and is communicated with the atmosphere or seawater environment at the outlet. The active compensation liquid chambers H and L are communicated or disconnected through the passive compensation mode switching valve (17) and are communicated or disconnected with the bidirectional variable pump (27) through the active compensation mode switching valve (18);

[0021] The bidirectional variable pump (27) is driven by a first servo motor (28), the oil drain of the bidirectional variable pump (27) is connected with an oil storage accumulator (25) through a one-way valve and a sixth stop valve (26), is connected with a oil supplement pump (24) through a one-way valve, the oil supplement pump (24) is driven by a constant speed motor (29), the oil supplement pump (15) is connected with an oil supplement accumulator (22) through a one-way valve and a fifth stop valve (23), is connected with a double-piston double-rod accumulator load pressure liquid cavity F through a one-way valve and a seventh stop valve (33), is connected with the inlet of a first cartridge-mounted one-way valve (19) and a second cartridge-mounted one-way valve (32) through a one-way valve, the side port and the outlet of the first cartridge-mounted one-way valve (19) are connected with the bidirectional variable pump (27) and the inlet of a first cartridge-mounted overflow valve (20), the outlet of the first cartridge-mounted one-way valve (20) is connected with the side port through a first overflow valve (21), the side port is connected with the oil supplement accumulator (22) through the fifth stop valve (23); the side port and the outlet of the second cartridge-mounted one-way valve (32) are connected with the bidirectional variable pump (27) and the inlet of a second cartridge-mounted overflow valve (31), the outlet of the second cartridge-mounted overflow valve (31) is connected with the side port through a second overflow valve (30), the side port is connected with the oil supplement accumulator (22) through the fifth stop valve (23).

[0022] In order to realize the functions of oil supplement and oil drain, different pressures are required for the cartridge-mounted, wherein the pressure of the first and second cartridge-mounted one-way valves is lower than that of the first and second cartridge-mounted overflow valves, when the device needs to supplement oil, the oil supplement pump drives the supplement oil to enter from the inlet of the first and second cartridge-mounted one-way valves and flows out to the compensation circuit, thereby supplementing oil for the system; opening the seventh stop valve can also supplement oil for the circuit between the double-piston double-rod accumulator and the compensation cylinder, when the pressure in the circuit is too high, oil drain is required, the high-pressure oil in the circuit enters from the inlet of the first and second cartridge-mounted overflow valves and flows out to the oil storage accumulator, thereby reducing the pressure in the circuit and realizing the safety protection function.

[0023] The double-piston double-rod accumulator load pressure liquid cavity F is connected with the rod cavity V2 of the compensation cylinder through a first throttle valve block (2) and a first stop valve (3), the rodless cavity V1 is connected with a low-pressure gas cylinder (7) through a second stop valve (5), a third stop valve (6) is connected with the low-pressure gas cylinder (7) as an exhaust valve.

[0024] The working principle of the present application is as follows:

[0025] Before the device works, the pressure provided by the gas cylinder group (13) and the pressure of the low-pressure gas cylinder (7) are set according to the sea conditions and the load, the fourth stop valve (16) is opened first, then the second throttle valve block (14) is gradually opened, and the gas is slowly charged into the passive compensation gas cavity G, so that the two active compensation liquid cavities H and L of the double-piston double-rod accumulator are at the position of equal volume, and the piston of the compensation cylinder (4) is at the intermediate position.

[0026] Before the device works, in order to prevent the device from affecting the compensation performance due to the decrease of the circuit pressure caused by oil leakage, the circuit needs to be supplemented with oil. The oil storage accumulator (25) and the stop valves (23) and (26) below the oil supplement accumulator (22) are opened. The active compensation mode switching valve (18) and the oil supplement pump (24) are controlled to open. The oil supplement pump (24) extracts oil from the oil storage accumulator (25) and guides the supplement oil to enter the inlets of the first and second cartridge check valves (19) and (32) and flow out to the compensation circuit to supplement the oil for the system. When it is necessary to supplement the circuit between the load pressure liquid cavity F of the double-piston double-rod accumulator in the device and the rod cavity V2 of the compensation cylinder, the seventh stop valve (33) and the first stop valve (2) are opened. The valve opening of the first throttle valve block (2) is adjusted to the maximum, and the circuit can be supplemented with oil.

[0027] When the pressure of the passive compensation gas cavity G of the double-piston double-rod accumulator in the device is too high, it needs to be discharged. When the device is in the air or a shallow water area with small water pressure, the excess gas can be directly discharged to the outside through the relief valve (15). When the device is in a deep water area with large water pressure, directly using the relief valve (15) to discharge gas will cause seawater to flow back into the gas bottle group. In order to avoid this phenomenon, the electromagnetic switch valve below the low-pressure gas collecting bottle is opened, and the excess gas is released into the low-pressure gas collecting bottle.

[0028] When the system performs the active compensation function, the active compensation mode switching valve (18) is opened, the passive compensation mode switching valve (17) is disconnected, the first throttle valve block (2) is fully opened, and the first stop valve (3) is opened. After the system is stable, the active compensation working mode can be performed.

[0029] During the active compensation process, the PLC control unit (10) takes the signals of the MRU (9), the displacement signals of the displacement sensor in the compensation cylinder (4), and the pressure signals of the pressure sensor as input signals, processes the displacement sensor signals in the double-piston double-rod accumulator (1) as feedback signals, and transmits the output signals to the bidirectional variable pump (27). By controlling the inclination angle and direction of the swash plate of the bidirectional variable pump (27), the oil quantity in the two active compensation liquid cavities H and L of the double-piston double-rod accumulator is adjusted, and the volume of the load pressure liquid cavity F is controlled to provide an active compensation force for the piston and indirectly control the movement stroke and position of the compensation cylinder. Together with the passive compensation force provided by the passive compensation gas cavity G, the load position is compensated.

[0030] When the platform rises, the active control unit controls the double-piston variable pump (27) to absorb oil from the double-piston accumulator active compensation liquid cavity L and supply oil to the active compensation liquid cavity H, the gas in the passive compensation gas cavity G enters the gas cylinder group (13), the volume of the gas cavity G decreases, the load pressure cavity F absorbs oil from the compensation cylinder rod cavity V2, the volume increases, so that the volume of the rod cavity V2 decreases, the gas in the low-pressure gas cylinder (7) enters the rodless cavity V1, the volume of the rodless cavity V1 increases, and the compensation cylinder piston rod is pushed outwards to maintain the relative invariability of the load position.

[0031] When the platform rises, the active control unit controls the double-piston variable pump (27) to absorb oil from the double-piston accumulator active compensation liquid cavity L and supply oil to the active compensation liquid cavity H, the gas in the passive compensation gas cavity G enters the gas cylinder group (13), the volume of the gas cavity G decreases, the load pressure cavity F absorbs oil from the compensation cylinder rod cavity V2, the volume increases, so that the volume of the rod cavity V2 decreases, the gas in the low-pressure gas cylinder (7) enters the rodless cavity V1, the volume of the rodless cavity V1 increases, and the compensation cylinder piston rod is pushed outwards to maintain the relative invariability of the load position.

[0032] When the system performs passive compensation function, the active compensation mode switching valve (18) is disconnected, the passive compensation mode switching valve (17) is connected, the first throttle valve block (2) is fully opened, and the first stop valve (3) is opened. After the system is stable, the passive compensation working mode can be performed.

[0033] When the passive compensation mode switching valve (17) is connected, the two active compensation liquid cavities of the double-piston double-rod accumulator are connected. When the platform rises, the load still has a tendency to remain in place under the action of inertia, which makes the compensation cylinder piston rod move downward, the volume of the compensation cylinder rodless cavity V1 increases, the volume of the compensation cylinder rod cavity V2 decreases, the oil flows into the double-load pressure liquid cavity F, the pressure of the load pressure liquid cavity F increases, the lower piston moves upward, the volume of the passive compensation gas cavity G decreases, the gas enters the gas cylinder group, and the pressure of the gas cylinder group increases. When the platform descends, the load still has a tendency to remain in place under the action of inertia, which makes the compensation cylinder piston rod move upward, the volume of the compensation cylinder rodless cavity V1 decreases, the gas in the rodless cavity V1 enters the low-pressure gas cylinder (7), the volume of the rod cavity V2 increases, the oil flows from the load pressure liquid cavity F into the rod cavity V2, the pressure of the load pressure liquid cavity F decreases, the lower piston moves downward, the volume of the passive compensation gas cavity G increases, the pressure decreases, and the gas in the gas cylinder group enters the passive compensation gas cavity G, thereby realizing passive heave compensation.

[0034] When the device works in the working environment of high sea state, due to high frequency of sea waves, the device is impacted greatly, if the device resonates, safety problem will be caused, the control strategy of variable damping is adopted, the active compensation mode switching valve (18) is closed, the passive compensation mode switching valve (17) is opened, and the first cut-off valve (3) is opened. The PLC control unit receives the displacement sensor signal on the compensation cylinder as the input signal, judges the sea state size according to the input signal, and applies the output signal to the first throttle valve block (2), adjusts the damping ratio of the device by controlling the opening size of the throttle valve block, so that the natural frequency of the device is changed, the natural frequency of the device is avoided from the sea wave frequency interval, and the resonance phenomenon of the device is prevented.

[0035] When the device needs to pass through the splash zone, due to the impact of sea waves in the splash zone on the load and the device, the stress change of the hoisting wire rope is large, the service life of the wire rope is reduced, and the breaking phenomenon occurs, therefore, the control strategy of variable damping and variable stiffness is adopted during the process that the device passes through the splash zone. When the device receives the signal of passing through the splash zone, the control unit closes the gas cylinder opening valve under the working gas cylinder in the gas cylinder group, only opens the splash zone gas cylinder, and controls the damping size of the system by adjusting the opening of the first and second throttle valve blocks (2), (14), utilizes the large compression stiffness to prevent the oil cylinder from moving too much when the compensation oil cylinder responds to the wave force impact buffer, causes mechanical impact and damage of the oil cylinder, reduces the impact force of the sea wave on the load and the device, reduces the stress fluctuation on the wire rope, and realizes the function that the device stably passes through the splash zone.

[0036] The deep water pressure compensation function is integrated in the double-piston double-rod accumulator, when the water depth pressure acts on the compensation device, the ratio of the acting force to the acting area of the compensation cylinder piston rod is the same as the ratio of the acting force to the acting area of the outer piston rod of the double-piston double-rod accumulator, so that the deep water pressure compensation function is realized.

[0037] The above is only an embodiment of the present application, the present application is not limited to this, any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present application without departing from the technical solution content of the present application still belongs to the protection scope of the technical solution of the present application.

Claims

1. A linear heave compensation device based on a double-piston double-rod accumulator, comprising a double-piston double-rod accumulator (1); a first throttle valve block (2); a first stop valve (3); a compensation cylinder (4); a second stop valve (5); a third stop valve (6); a low-pressure gas cylinder (7); a pressure sensor (8); an MRU motion posture sensor (9); a PLC control unit (10); a displacement sensor (11); a gas cylinder switch valve (12); a gas cylinder group (13); a second throttle valve block (14); a discharge valve (15); and a fourth stop valve (16). ; Passive compensation mode switching valve (17); Active compensation mode switching valve (18); First cartridge check valve (19); First cartridge relief valve (20); First relief valve (21); Oil replenishment accumulator (22); Fifth stop valve (23); Oil replenishment pump (24); Oil storage accumulator (25); Sixth stop valve (26); Bidirectional variable pump (27); First servo motor (28); Constant speed motor (29); Second relief valve (30); Second cartridge relief valve (31); Second cartridge check valve (32); Seventh stop valve (33); The double-piston double-rod accumulator (1) is composed of an upper piston (1.2), an inner piston rod (1.4), a lower piston (1.6), an outer piston rod (1.9) and a cylinder (1.8). The upper piston is connected to the lower piston via the inner piston rod, and the lower piston is connected to the outer piston rod. The double-piston double-rod accumulator is divided into four chambers: a passive compensation air chamber G, active compensation liquid chambers H and L, and a load pressure liquid chamber F. The compensation cylinder (4) is composed of a rodless chamber V1 (4.1), a piston (4.2), a rod chamber V2 (4.3), a piston rod (4.4), a cylinder barrel and an earring (4.6). The low-pressure gas cylinder (7) is connected to the rodless chamber V1 of the compensation cylinder through a second stop valve (5). The earring (4.6) is used to suspend the load. The rod chamber V2 (4.3) bears all loads during the heave compensation movement. The rod chamber V2 (4.3) of the compensation cylinder is connected to the load pressure liquid chamber F (1.7) of the double-piston double-rod accumulator through a first throttle valve block (2) and a first stop valve (3), and transmits the load pressure to the lower piston (1.6). The passive compensation air chamber G of the dual-piston dual-rod accumulator is connected to the gas cylinder group (13) through the second throttle valve block (14), the fourth stop valve (16), and the gas cylinder switch valve (12); the inlet of the discharge valve (15) is connected to the fourth stop valve (16), and the outlet is connected to the atmosphere or seawater environment; the active compensation liquid chambers H and L are connected or disconnected through the passive compensation mode switching valve (17), and are connected or disconnected with the bidirectional variable pump (27) through the active compensation mode switching valve (18); The bidirectional variable pump (27) is driven by the first servo motor (28). The oil drain port of the bidirectional variable pump (27) is connected to the oil storage accumulator (25) through a one-way valve and a sixth stop valve (26). The oil drain port of the bidirectional variable pump (27) is connected to the oil storage accumulator (25) through the one-way valve and the sixth stop valve (26). The oil drain port of the bidirectional variable pump (27) is connected to the oil replenishment pump (24) through the one-way valve. The oil replenishment pump (24) is driven by the constant speed motor (29). The oil replenishment pump (24) is connected to the oil replenishment accumulator (22) through the first one-way valve and the fifth stop valve (23). The oil replenishment pump (24) is connected to the load pressure liquid chamber of the double-piston double-rod accumulator through the first one-way valve and the seventh stop valve (33). F is connected, the oil charge pump (24) is also connected to the inlet of the first plug-in one-way valve (19) and the second plug-in one-way valve (32) through the first one-way valve, the side port and the control port of the first plug-in one-way valve (19) are connected to the inlet of the two-way variable pump (27) and the first plug-in relief valve (20), the control port of the first plug-in relief valve (20) is connected to the side port of the first plug-in relief valve (20) through the first relief valve (21), and the side port of the first plug-in relief valve (20) is connected to the oil charge accumulator (22) through the fifth stop valve (23); The side port and control port of the second cartridge check valve (32) are connected to the inlet of the bidirectional variable pump (27) and the second cartridge relief valve (31). The control port of the second cartridge relief valve (31) is connected to the side port of the second cartridge relief valve (31) through the second relief valve (30). The side port of the second cartridge relief valve (31) is connected to the oil replenishment accumulator (22) through the fifth stop valve (23). When the pressure in the circuit is too high, oil needs to be drained. The high-pressure oil in the circuit enters from the inlet of the first and second cartridge relief valves, flows out from the side port, and returns to the oil replenishment accumulator. In the double-piston double-rod accumulator (1), there are two piston rods with different diameters. The inner piston rod (1.4) has a larger diameter, which reduces the annular area of ​​the active compensation liquid chambers H and L and reduces the flow rate required by the pump. The inner piston rod (1.4) adopts a hollow rod structure to reduce weight. In deep water, the outer piston rod (1.9) is connected to the seawater environment to achieve the function of deep water pressure compensation. The outer piston rod diameter D0, the compensation cylinder piston rod diameter D1, the annular area S1 of the load pressure liquid chamber F and the annular area A1 of the compensation cylinder rod chamber V2 must meet the following relationship The gas cylinder group (13) is composed of four gas cylinders, namely a working gas cylinder, a splash zone gas cylinder, a high-pressure gas source cylinder and a low-pressure gas collecting cylinder. The gas cylinder outlet is connected to a gas cylinder switch valve (12). In the normal working mode, the working gas cylinder and the splash zone gas cylinder provide passive compensation force. In the splash zone mode, the working gas cylinder is closed and the splash zone gas cylinder alone provides passive compensation force. The high-pressure gas source cylinder supplements the pressure of the other gas cylinders and the low-pressure gas collecting cylinder recovers excess gas. The gas cylinder group (13) is connected to the passive compensation air chamber G of the double-piston double-rod accumulator through a second throttle valve block (14). The discharge valve (15) is used for exhausting gas.

2. A linear heave compensation device based on a dual-piston dual-rod accumulator according to claim 1, characterized in that: During the compensation process, the static load and dynamic load of the compensation cylinder (4) directly act on the rod chamber V2 of the compensation cylinder, and the pressure is transmitted to the load pressure liquid chamber F of the accumulator. The gas cylinder group (13) is connected to the passive compensation gas chamber G to provide passive compensation force. The two active compensation liquid chambers H and L of the accumulator are connected to a bidirectional variable pump (27), providing a bidirectional active compensation force for the device, indirectly driving the compensation cylinder (4) to realize the heave compensation function. When the passive compensation mode switching valve (17) is opened and the active compensation mode switching valve (18) is closed, it is in the passive compensation mode; when the passive compensation mode switching valve (17) is closed and the active compensation mode switching valve (18) is opened, it switches to the active compensation mode.

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